DETAILED ACTION
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
This is in response to Applicant’s arguments and amendments filed on 02/02/2026 amending Claims 23, 26, 28, and 31 and canceling Claims 25, 27, 30, and 32. Claims 23, 26, 28, and 31 are examined.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 23, 26, 28, and 31 are rejected under 35 U.S.C. 103 as being unpatentable over Roberge (2020/0088102A1) in view of Martz (3,948,043) in view of Johnson (3,313,103) in view of Mohamed Nawar, “Fuel Consumption Issue for Gas Turbine 9fa”, Automation & Control Engineering Forum, July 2018 [accessed on 10/24/2025 at https://control.com/forums/threads/fuel-consumption-issue-for-gas-turbine-9fa.47227/], hereinafter “Mohamed” in view of Iasillo et al. (7,770,400) as evidenced by Ulber et al. (2024/0343561A1).
Regarding Claim 23, Roberge teaches, in Figs. 1 and 3, the invention as claimed, including a fuel supply system comprising: a main fuel line (A) connected to fuel tank (46) configured to store liquid fuel (cryogenic fuel); a flow control valve (A – circle enclosing an X, Para. [0016] “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation.” ‘Control the flow of fuel’ and ‘regulate the amount of fuel’ were just different ways of saying ‘adjust a flow rate percentage of the liquid fuel’.) configured to adjust a flow rate percentage of the liquid fuel flowing through the main fuel line (A); a vaporizer (36) connected to an end of the main fuel line (A[Wingdings font/0xE0]C[Wingdings font/0xE0]D or A[Wingdings font/0xE0]E), the vaporizer (36) being configured to heat and vaporize the liquid fuel (cryogenic fuel) via heat exchange between a heating medium (FE) and at least a part of the liquid fuel (cryogenic fuel) from the main fuel line (A); a gaseous fuel line (F[Wingdings font/0xE0]G) connected to the vaporizer (36), the gaseous fuel line (F[Wingdings font/0xE0]G) being configured to guide gaseous fuel, which is the fuel vaporized by the vaporizer (36), as fuel to a combustor (24) of a gas turbine (12); a liquid fuel line (B) configured to guide liquid fuel (cryogenic fuel), which has not undergone heat exchange [As shown in Figs. 1 and 3 the pressurized liquid fuel from the main fuel pump (40) directly flowed to the combustor (24) via liquid fuel line (B).] with the heating medium (FE) at the vaporizer (36), from the main fuel line (A) as fuel to the combustor (24); a switching device [Para. [0016] - plurality of valves A - E] configured to switch a fuel supply state between a plurality of states [Para. [0016] - “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] - “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation”.] including a first state (gaseous fuel state – Para. [0024] “Gaseous fuel exiting fuel turbine 38 can be supplied to combustor 24 through fuel line G”.) in which the gaseous fuel is guided from the gaseous fuel line (F [Wingdings font/0xE0]G) to the combustor (24) and the liquid fuel is not supplied to the combustor (24) [Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”], and a second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) in which the liquid fuel is guided from the liquid fuel line (B) to the combustor (24) and the gaseous fuel is not supplied to the combustor (24) [Para. [0026] – “Exhaust heat exchanger 36 transfers waste heat from exhaust gas to the fuel to vaporize fuel as necessary to drive turbo-generator 14. From exhaust heat exchanger 36, the gaseous fuel is delivered to fuel turbine 38 via fuel line F.” Obviously during the start-up phase of a gas turbine engine there was no exhaust gas and therefore no waste heat from the exhaust gas to vaporize the liquid fuel into gaseous fuel. Therefore, during the start-up phase of the gas turbine engine of Roberge only liquid fuel was supplied to the combustor because the gaseous fuel had yet to be created by vaporizing the liquid fuel using the hot exhaust gas.], and a control device (48) that controls the switching device (Para. [0016] - “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] - “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation”.), wherein, the control device (48) causes the switching device (plurality of valves A – E) to implement the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when the flow rate percentage of the fuel flowing in the main fuel line (A) is less than a predetermined α% (any percentage greater than 0% and less than 100%) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the fuel flowing in the main fuel line (A) when the gas turbine is at a rated output [Note: The following well-known in the art statement is taken to be admitted prior art because Applicant failed to traverse Examiner’s assertion of Official Notice in the Office Action mailed on 05/15/2025 in Applicant’s reply filed on 10/01/2025, MPEP 2144.03(C). Examiner takes Official Notice that “rated output” of a gas turbine was the maximum power output by that gas turbine when rated at the International Organization for Standardization (ISO) conditions: 15°C/60°F, 60% relative humidity, and 101.3 kPa. Gas turbine power output and thermal efficiency were inversely related to ambient temperature and proportional to ambient pressure, so rating different gas turbine engines at standard ISO conditions was the conventional method of standardizing the operation of different gas turbine engines so their power output could be compared.], wherein the control device (48) is configured to receive an external output request (Out of the 162,128 patent documents related to gas turbines searched on 10/23/2025 only the PGPubs of the instant application and a child application used the phrase ‘external output request’. Refer to the attached Search History which showed the text search of ‘external output request’ yielded only two hits which were the PGPubs of the instant application and a child application. Therefore the phrase ‘external output request’ is NOT a term of art in the gas turbine art. Furthermore, Applicant’s Specification failed to define the meaning of ‘external output request’ because it was only disclosed in Paragraphs [0033], [0087], and [0103] without any details as to the meaning of ‘external output request’. Furthermore, the gas turbine engine of Roberge was not a closed system because, during operation, fuel and air from external sources flowed into the gas turbine engine while high temperature exhaust gases, waste heat, and/or electricity flowed out of the gas turbine, i.e., the external outputs. Consequently, the broadest reasonable interpretation of ‘external output request’ is any external input to the control device that would have resulted in an external output from the gas turbine engine. For example, a start-up signal sent to the control device would have come from an external source, e.g., human operator or external computer network, and would have resulted in the gas turbine generating external output, e.g., hot exhaust, electricity, and/or propulsive thrust. Roberge Para. [0016] teaches, “Controller 48 can be configured to receive, transmit, and/or process sensor data and/or signals for the operation of system 10.” Para. [0016] also teaches “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation.” Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.” Therefore, during startup, i.e., second state, the controller/control device received an external output request and sent a signal for flow control valve B to open so that liquid fuel would have been directly supplied to the gas turbine combustor.) for the gas turbine (12).
Applicant’s Specification disclosed, in Para. [0038], “The amount of fuel supplied to the gas turbine 10 gradually increases over time during the time period from startup to rated operation. Also, as described above, the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is less than the rated output is less than the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is the rated output. Herein, the fuel flow rate percentage when the output request is the rated output is 100%, and the fuel flow rate percentage before startup is 0%.” Applicant’s Para. [0038] merely describes the conventional operation of gas turbine engines. It was a scientific fact that before startup, i.e., when a gas turbine engine was shut down, the fuel flow rate percentage was 0% because no fuel would have been flowing into the combustion chamber(s) of the gas turbine engine. It was a scientific fact that at rated output operation, i.e., gas turbine engine maximum power output at ISO conditions, the fuel flow rate percentage would have been 100% because outputting maximum rated power, i.e., 100% power output, required the gas turbine to receive and burn the maximum flow rate of fuel, 100% fuel flow rate. Similarly, it was a scientific fact that the amount of fuel supplied to a gas turbine would have gradually increased over time during the time period from startup to rated operation since startup was 0% fuel flow rate and rated operation was 100% fuel flow rate. As shown by Martz, in Figs. 5 and 8, Col. 2, ll. 25 – 40, Col. 11, ll. 30 – 35, Col. 13, ll. 50 – 55, and Col. 14, l. 60 to Col. 15, l. 5, fuel flow rate generally linearly increased over time during the time period from startup to rated operation of a gas turbine engine. Martz - Fig. 5 and Col. 10, ll. 20 - 45, showed the minimum fuel flow rate at startup, then the fuel flow rate gradually increased as the gas turbine rotational speed increased to synchronous speed of 3,600 rpm (revolutions per minute). At the synchronous speed the gas turbine started driving a load, in this case an electric generator, and gradually increased the gas turbine power output up to the rated output, in this case 80 Megawatts – Col. 5, ll. 65 – 68, as the fuel flow rate increased to the maximum flow rate of fuel, 100% fuel flow rate. Martz - Fig. 8 and Col. 13, ll. 50 – 55, showed a linear relationship (801) between the gaseous fuel flow rate and the gas turbine power output in Megawatts.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that Roberge teaches the control device (48) causes the switching device (plurality of valves A – E) to implement the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when a flow rate percentage of the fuel flowing in the main fuel line (A) is less than a predetermined α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature. Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the fuel flowing in the main fuel line (A) when the gas turbine is at a rated output.
Roberge is silent on said liquid fuel being liquid ammonia and said gaseous fuel being gaseous ammonia.
Johnson teaches a similar gas turbine engine (12 – Fig. 1) having liquid fuel being liquid ammonia (NH3 – Col. 2, ll. 50 – 55 “anhydrous liquid ammonia”) stored in an ammonia tank (Fig. 2) where the liquid ammonia (NH3) was directly (36) flowed to the combustor (28) and where gaseous ammonia (26 – Col. 3, ll. 1 – 5 and ll. 40 - 60) could also be flowed to the combustor (28).
It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify Roberge with the liquid ammonia fuel, taught by Johnson, because all the claimed elements, i.e., the gas turbine engine having a combustor, the ammonia fuel tank, the main ammonia/fuel line, fuel pump, vaporizer, and gaseous ammonia/fuel line, were known in the art, and one skilled in the art could have substituted the liquid ammonia fuel stored in the ammonia tank, taught by Johnson, for the liquid fuel stored in the cryogenic fuel tank of Roberge, with no change in their respective functions, to yield predictable results, i.e., the liquid ammonia would have been directedly supplied to the combustor of the gas turbine engine as liquid fuel during the startup mode until the gas turbine engine heated up to steady-state operating temperature where the waste heat from the gas turbine engine would have been used to vaporized the liquid ammonia into gaseous ammonia that was then supplied to the combustor of the gas turbine engine as gaseous fuel. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1395; MPEP 2143(B). It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, that the combination of Roberge, i.v., Martz and Johnson, would have taught an ammonia tank, main ammonia line, gaseous ammonia line, liquid ammonia line, etcetera because adding “ammonia” to the name of a structural device did not change the structure or function of the device.
Roberge, i.v., Martz and Johnson, as discussed above, is silent on wherein said control device is configured to determine a flow rate percentage based on the external output request, instruct the flow control valve to adjust the flow rate percentage to be the determined flow rate percentage, and to cause the switching device to implement the first state.
Martz further teaches, in Figs. 1 – 11B, a gas turbine control device (50 – Fig. 1) was configured to receive an external output request (As discussed above, the broadest reasonable interpretation of ‘external output request’ is any external input to the control device that would have resulted in an external output from the gas turbine engine. For example, a start-up signal sent to the control device would have come from an external source, e.g., human operator or external computer network, and would have resulted in the gas turbine generating external output, e.g., hot exhaust, electricity, and/or propulsive thrust. Martz teaches in Fig. 3 – operator panel 102C, Fig. 4 – operator panel 402G, Fig. 6 – starting (1st input to square labeled ‘Select operating mode’ in top left-hand side of figure) and operator load demand (4th input to square labeled ‘Select operating mode’ in top left-hand side of figure), Martz teaches, in Abstract, “A megawatt load control system varies a fuel control signal to govern a detected power output according to a reference value, the fuel control signal determining the flow rate of fuel to a gas turbine”. Martz teaches, in Col. 7, ll. 25 – 30, “an analog startup control included in each of the gas turbine controls 104C and 106C automatically schedules fuel during gas turbine startups”. Martz teaches, in Col. 7, ll. 35 – 45, “In the operator automatic mode, the computers 58G and 100C perform various control functions which provide for automatic startup and automatic loading of the gas and steam turbines under the direction of the operator on a turbine-by-turbine basis”. Martz teaches, in Col. 7, ll. 45 – 55, “Under plant coordinated control, the computer 58G generally directs the plant operation through startup, synchronization and loading to produce the plant power demand”.), said control device (50) is configured to determine a flow rate based on the external output request (Col. 8, ll. 10 – 25, “the turbines are accelerated to synchronous speed, the generators are synchronized and the fuel and steam valves are positioned to operate the turbines at the demand load levels. The manner in which the control system 50 is configured and the manner in which it functions throughout startup and loading depends on the selected plant mode and the selected or forced plant configuration and the real time process behavior”), instruct the flow control valve to adjust the flow rate to be the determined flow rate (Col. 10, ll. 50 – 55, “Generally, once a demand is applied to a load control 424G in the megawatt load control system 400G, the fuel reference is ramped from its present value toward the demand value at a specified rate”. Col. 11, ll. 1 – 10, “…the load reference is proportional to megawatts and becomes a feedforward demand for fuel valve position after conversion from megawatts to valve position…”. Col. 11, ll. 55 – 60, “A fuel control signal is generated on a line 701A of FIG. 7A by the control system 50 (not shown) and the fuel flow to the combustor of the gas turbine 12 is controlled in accordance with the signal on the line 701A”. As shown in Figs. 7B and 10B, fuel control signal 701A ended up controlling the position of fuel valve 709A and/or 717A.), and to cause a switching device to implement the first state (Col. 12, ll. 10 – 30, “The signal on the line 703A has two steady state signal levels, namely, a first signal level corresponding to a numerical zero, in which case the output signal of the multiplier 704A is zero and the combustor of the gas turbine 12 receives a flow of gas, and a second signal level corresponding to a numerical one, in which case the output signal of the multiplier 704A is equal to the fuel control signal on the line 701A, and the combustor of the gas turbine 12 operates solely on oil. … The time of initiation and the ramp rate of such a ramp signal are controlled by a plant operator or by outputs from the control system 50, as schematically illustrated by the input arrows to the transfer ramp generator 702A labeled "operator input" and "control system input."”.).
Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Martz, would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz and Johnson, and the results would have been predictable and readily recognized, that configuring the control device to determine a flow rate based on the external output request, instruct the flow control valve to adjust the flow rate to be the determined flow rate, and to cause the switching device to implement the first state would have facilitated conventional computer control of a dual fuel type gas turbine fuel supply system which supplied a sufficient flow rate of fuel to the gas turbine combustor to satisfy the external output request. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C).
Roberge, i.v., Martz and Johnson, as discussed above, is silent on said flow rate and said determined flow rate being a flow rate percentage and a determined flow rate percentage and silent on said switching device implementing said first state being in response to the determined flow rate of the fuel flowing in the main ammonia line exceeding the α%. However, as discussed above, Roberge teaches, in Para. [0025], the first state with only gaseous fuel and no liquid fuel. Roberge Para. [0025] “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.” As discussed above, Roberge teaches, in Para. [0026], the second state being used for the start-up phase of the gas turbine engine. Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”
Martz further teaches, in Fig. 5-A (marked-up below), a chart showing the fuel flow (Y-axis) during start-up to full speed no load (FSNL) and then to rated output/load. Martz further teaches, in Col. 10, ll. 20 – 30, “…gas turbine startup in the automatic mode is controlled from an ignition speed of approximately 900 rpm to synchronous speed. At ignition, the fuel reference is set at a fixed value and upon detection of a successful ignition the speed reference is increased to generate an increasing output reference for the fuel control”. Martz further teaches, in Col. 10, ll. 40 – 45, “At the end of the acceleration period, the gas turbine is in a run standby state at a speed of approximately 3,600 rpm and it is ready to be synchronized”. The “standby state at a speed of approximately 3,600 rpm” was known in the gas turbine art as “full speed no load” (FSNL) because the gas turbine was at its full operational speed of 3,600 rpm but was not generating any electricity, i.e., no load. The gas turbine full operational speed was 3,600 rpm to generate alternating current electricity at a frequency of 60 Hertz which was the frequency of the electrical grid in the United States of America. The equation for frequency (f) = (Engine Speed (N) X Number of Poles (P)) / 120, so a 2-pole electric generator had to spin at 3,600 rpm to produce 60 Hz alternating current electricity. Martz further teaches, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”.
Mohamed teaches, on Pg. 3, second paragraph, “It requires a certain amount of fuel just to achieve and maintain rated speed (FSNL)”. Mohamed teaches, on Pg. 3, third paragraph, “It usually requires approximately 25% of rated fuel flow-rate just to maintain rated speed (FSNL). … And it requires approximately 75% of rated fuel flow to make power from generator breaker closure (0 MW) to Base Load”. Mohamed teaches, on Pg. 5, fifth paragraph, calculating/determining a flow rate percentage based on an external output request of 150 MegaWatts (MW) for an example gas turbine with a rated output of 245 MegaWatts (MW), maximum fuel flow rate at rated output of 14 kg/second (100% flow rate), 25% fuel flow rate percentage at FSNL (which would be ~3.5 kg/s). The calculation steps were:
Step 1: Calculate the fuel required to produce the incremental load.
First, find the fuel consumed just for power generation (above the FSNL baseline) at the rated load:
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Step 2: Determine the proportion of the demanded load to the rated load.
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Step 3: Calculate the incremental fuel needed for the demanded load.
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Step 4: Add the FSNL fuel back to find the total fuel flow rate for the demanded load.
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Step 5: Convert the determined fuel flow rate to flow rate percentage by dividing the determined fuel flow rate by the maximum fuel flow rate at rated output, i.e., maximum fuel flow rate.
9.926 kg/s / 14 kg/s = 0.709 or around 71% flow rate percentage for an output request/demand load of 150 MW.
Marking up Martz – Fig. 5 to show the numerical values in the example gas turbine of Mohamed results in Fig. 5-A shown below.
Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Roberge, Martz, and Mohamed would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz and Johnson, and the results would have been predictable and readily recognized, that configuring said control device to cause said switching device to implement said first state in response to the determined flow rate percentage of the fuel flowing in the main ammonia line exceeding the α% (in this case ~25% at FSNL operating condition) would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia and then transition from only liquid ammonia (second state) to eventually only gaseous ammonia (first state). KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C).
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It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, and Mohamed, said control device would have been configured to receive an external output request (e.g., 150 MW) for the gas turbine, determine a flow rate percentage (e.g., ~71%) based on the external output request, instruct the flow control valve to adjust the flow rate percentage to be the determined flow rate percentage (required to satisfy the external output request), and to cause the switching device (valves) to implement the first state in response to the determined flow rate percentage (e.g., ~71%) of the fuel flowing in the main ammonia line exceeding the α% (e.g. 25% at FSNL operating condition) because this was the conventional operating steps/method of conventional gas turbines.
Roberge, i.v., Martz, Johnson, and Mohamed, further teaches including, as shown in Fig. 5-A above, wherein the control device is configured to cause the switching device to implement a third state (labeled in Fig. 5-A), in which both the gaseous ammonia from the gaseous ammonia line and the liquid ammonia from the liquid ammonia line are guided to the combustor (as discussed above both Roberge and Martz taught a transition state where both liquid fuel and gaseous fuel were supplied to the combustor), in response to the determined flow rate percentage of the fuel flowing in the main ammonia line being α% (e.g. 25% at FSNL operating condition), and wherein in the third state (labeled in Fig. 5-A), the flow rate percentage of the liquid ammonia guided to the combustor gradually decreases over time (solid line labeled “Decreasing Liquid fuel”) and the flow rate percentage of the gaseous ammonia guided to the combustor gradually increases over time (dashed line labeled “Increasing Gaseous fuel”). Martz teaches, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”.
Roberge, i.v., Martz, Johnson, and Mohamed, as discussed above, is silent on “…or the flow rate percentage of the liquid ammonia guided to the combustor gradually increases over time and the flow rate percentage of the gaseous ammonia guided to the combustor gradually decreases over time”.
Iasillo teaches, in Figs. 1 – 11 (Fig. 6 marked-up below), Abstract, Col. 1, ll. 10 – 21, Col. 3, ll. 40 – 55, and Col. 4, ll. 5 – 35, a similar gas turbine engine (100 – Fig. 1) that switched from a second state (100% liquid fuel, 0% gaseous fuel) guided to the combustor (110), to a third state in which the gaseous fuel flow rate percentage increases over time (X-axis) and the liquid fuel flow rate percentage decreases over time (X-axis) until a first state (0% liquid fuel, 100% gaseous fuel) was reached where only gaseous fuel was guided to the combustor (110), after operating in the first state for a period of time the first state transitions to a different third state in which the gaseous fuel flow rate percentage decreases over time (X-axis) and the liquid fuel flow rate percentage increases over time (X-axis) until the second state (100% liquid fuel, 0% gaseous fuel) was reached so that the liquid/gaseous fuel flow rate percentages were based on the respective fuel flow rates necessary to satisfy the fuel reference demand for a given power output, Col. 8, ll. 10 – 65 and Col. 10, ll. 5 – 60. As evidenced by Ulber, in Para. [0101], ammonia had a lower heating value of 18.6 MJ/kg (MegaJoules per kilogram). The heating value was an inherent material property that refers to the energy released during combustion, which is generally consistent for anhydrous ammonia regardless of its state.
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Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Iasillo would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz, Johnson, and Mohamed, and the results would have been predictable and readily recognized, that configuring said control device to cause said switching device to implement said first state in response to the determined flow rate percentage of the fuel flowing in the main ammonia line exceeding the α% (in this case ~25% at FSNL operating condition) would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia. In other words, transitioning from only liquid ammonia (second state) to eventually only gaseous ammonia (first state) by decreasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously increasing the gaseous fuel flow rate percentage over the same time period, then operating the gas turbine in the first state (100% gaseous ammonia) for a period of time until a different third state is started where the transition was from only gaseous ammonia (first state) to eventually only liquid ammonia (second state) by increasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously decreasing the gaseous fuel flow rate percentage over the same time period, as shown in Iasillo – Fig. 6 (marked-up above). Iasillo teaches, in Col. 4, ll. 5 – 35, that during a transfer from one fuel source to another, e.g., liquid fuel to gaseous fuel or vice versa, it was desired that continuity of turbine output power be maintained while minimizing any undershoots or overshoots of output power and temperature. In other words, to maintain a constant exhaust gas temperature and constant gas turbine power output the amount of fuel energy, i.e., the lower heating value, supplied to the combustor during the first state (only gaseous ammonia), second state (only liquid ammonia), and third state (mixture of both gaseous ammonia and liquid ammonia) had to be relatively constant. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate decrease in liquid ammonia guided to the combustor, i.e., less liquid ammonia equals less energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate increase in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same. It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate increase in liquid ammonia guided to the combustor, i.e., more liquid ammonia equals more energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate decrease in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same.
Regarding Claim 26, Roberge teaches, in Figs. 1 and 3, the invention as claimed, including a fuel supply system comprising: a main fuel line (A) connected to fuel tank (46) configured to store liquid fuel (cryogenic fuel); a flow control valve (A – circle enclosing an X, Para. [0016] “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation.” ‘Control the flow of fuel’ and ‘regulate the amount of fuel’ were just different ways of saying ‘adjust a flow rate percentage of the liquid fuel’.) configured to adjust a flow rate percentage of the liquid fuel flowing through the main fuel line (A); a vaporizer (36) connected to an end of the main fuel line (A[Wingdings font/0xE0]C[Wingdings font/0xE0]D or A[Wingdings font/0xE0]E), the vaporizer (36) being configured to heat and vaporize the liquid fuel (cryogenic fuel) via heat exchange between a heating medium (FE) and at least a part of the liquid fuel (cryogenic fuel) from the main fuel line (A); a gaseous fuel line (F[Wingdings font/0xE0]G) connected to the vaporizer (36), the gaseous fuel line (F[Wingdings font/0xE0]G) being configured to guide gaseous fuel, which is the fuel vaporized by the vaporizer (36), as fuel to a combustor (24) of a gas turbine (12); a liquid fuel line (B) configured to guide liquid fuel (cryogenic fuel), which has not undergone heat exchange [As shown in Figs. 1 and 3 the pressurized liquid fuel from the main fuel pump (40) directly flowed to the combustor (24) via liquid fuel line (B).] with the heating medium (FE) at the vaporizer (36), from the main fuel line (A) as fuel to the combustor (24); a switching device [Para. [0016] - plurality of valves A - E] configured to switch a fuel supply state between a plurality of states [Para. [0016] - “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] - “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation”.] including a first state (gaseous fuel state – Para. [0024] “Gaseous fuel exiting fuel turbine 38 can be supplied to combustor 24 through fuel line G”.) in which the gaseous fuel is guided from the gaseous fuel line (F [Wingdings font/0xE0]G) to the combustor (24) and the liquid fuel is not supplied to the combustor (24) [Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”], and a second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) in which the liquid fuel is guided from the liquid fuel line (B) to the combustor (24) and the gaseous fuel is not supplied to the combustor (24) [Para. [0026] – “Exhaust heat exchanger 36 transfers waste heat from exhaust gas to the fuel to vaporize fuel as necessary to drive turbo-generator 14. From exhaust heat exchanger 36, the gaseous fuel is delivered to fuel turbine 38 via fuel line F.” Obviously during the start-up phase of a gas turbine engine there was no exhaust gas and therefore no waste heat from the exhaust gas to vaporize the liquid fuel into gaseous fuel. Therefore, during the start-up phase of the gas turbine engine of Roberge only liquid fuel was supplied to the combustor because the gaseous fuel had yet to be created by vaporizing the liquid fuel using the hot exhaust gas.], and a control device (48) that controls the switching device (Para. [0016] - “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] - “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation”.), wherein, the control device (48) causes the switching device (plurality of valves A – E) to implement the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when the flow rate percentage of the fuel flowing in the main fuel line (A) is less than a predetermined α% (any percentage greater than 0% and less than 100%) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the fuel flowing in the main fuel line (A) when the gas turbine is at a rated output [Note: The following well-known in the art statement is taken to be admitted prior art because Applicant failed to traverse Examiner’s assertion of Official Notice in the Office Action mailed on 05/15/2025 in Applicant’s reply filed on 10/01/2025, MPEP 2144.03(C). Examiner takes Official Notice that “rated output” of a gas turbine was the maximum power output by that gas turbine when rated at the International Organization for Standardization (ISO) conditions: 15°C/60°F, 60% relative humidity, and 101.3 kPa. Gas turbine power output and thermal efficiency were inversely related to ambient temperature and proportional to ambient pressure, so rating different gas turbine engines at standard ISO conditions was the conventional method of standardizing the operation of different gas turbine engines so their power output could be compared.], wherein the control device (48) is configured to receive an external output request (Out of the 162,128 patent documents related to gas turbines searched on 10/23/2025 only the PGPubs of the instant application and a child application used the phrase ‘external output request’. Refer to the attached Search History which showed the text search of ‘external output request’ yielded only two hits which were the PGPubs of the instant application and a child application. Therefore the phrase ‘external output request’ is NOT a term of art in the gas turbine art. Furthermore, Applicant’s Specification failed to define the meaning of ‘external output request’ because it was only disclosed in Paragraphs [0033], [0087], and [0103] without any details as to the meaning of ‘external output request’. Furthermore, the gas turbine engine of Roberge was not a closed system because, during operation, fuel and air from external sources flowed into the gas turbine engine while high temperature exhaust gases, waste heat, and/or electricity flowed out of the gas turbine, i.e., the external outputs. Consequently, the broadest reasonable interpretation of ‘external output request’ is any external input to the control device that would have resulted in an external output from the gas turbine engine. For example, a start-up signal sent to the control device would have come from an external source, e.g., human operator or external computer network, and would have resulted in the gas turbine generating external output, e.g., hot exhaust, electricity, and/or propulsive thrust. Roberge Para. [0016] teaches, “Controller 48 can be configured to receive, transmit, and/or process sensor data and/or signals for the operation of system 10.” Para. [0016] also teaches “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation.” Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.” Therefore, during startup, i.e., second state, the controller/control device received an external output request and sent a signal for flow control valve B to open so that liquid fuel would have been directly supplied to the gas turbine combustor.) for the gas turbine (12).
Applicant’s Specification disclosed, in Para. [0038], “The amount of fuel supplied to the gas turbine 10 gradually increases over time during the time period from startup to rated operation. Also, as described above, the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is less than the rated output is less than the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is the rated output. Herein, the fuel flow rate percentage when the output request is the rated output is 100%, and the fuel flow rate percentage before startup is 0%.” Applicant’s Para. [0038] merely describes the conventional operation of gas turbine engines. It was a scientific fact that before startup, i.e., when a gas turbine engine was shut down, the fuel flow rate percentage was 0% because no fuel would have been flowing into the combustion chamber(s) of the gas turbine engine. It was a scientific fact that at rated output operation, i.e., gas turbine engine maximum power output at ISO conditions, the fuel flow rate percentage would have been 100% because outputting maximum rated power, i.e., 100% power output, required the gas turbine to receive and burn the maximum flow rate of fuel, 100% fuel flow rate. Similarly, it was a scientific fact that the amount of fuel supplied to a gas turbine would have gradually increased over time during the time period from startup to rated operation since startup was 0% fuel flow rate and rated operation was 100% fuel flow rate. As shown by Martz, in Figs. 5 and 8, Col. 2, ll. 25 – 40, Col. 11, ll. 30 – 35, Col. 13, ll. 50 – 55, and Col. 14, l. 60 to Col. 15, l. 5, fuel flow rate generally linearly increased over time during the time period from startup to rated operation of a gas turbine engine. Martz - Fig. 5 and Col. 10, ll. 20 - 45, showed the minimum fuel flow rate at startup, then the fuel flow rate gradually increased as the gas turbine rotational speed increased to synchronous speed of 3,600 rpm (revolutions per minute). At the synchronous speed the gas turbine started driving a load, in this case an electric generator, and gradually increased the gas turbine power output up to the rated output, in this case 80 Megawatts – Col. 5, ll. 65 – 68, as the fuel flow rate increased to the maximum flow rate of fuel, 100% fuel flow rate. Martz - Fig. 8 and Col. 13, ll. 50 – 55, showed a linear relationship (801) between the gaseous fuel flow rate and the gas turbine power output in Megawatts.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that Roberge teaches the control device (48) causes the switching device (plurality of valves A – E) to implement the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when a flow rate percentage of the fuel flowing in the main fuel line (A) is less than a predetermined α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature. Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the fuel flowing in the main fuel line (A) when the gas turbine is at a rated output.
Roberge is silent on said liquid fuel being liquid ammonia and said gaseous fuel being gaseous ammonia.
Johnson teaches a similar gas turbine engine (12 – Fig. 1) having liquid fuel being liquid ammonia (NH3 – Col. 2, ll. 50 – 55 “anhydrous liquid ammonia”) stored in an ammonia tank (Fig. 2) where the liquid ammonia (NH3) was directly (36) flowed to the combustor (28) and where gaseous ammonia (26 – Col. 3, ll. 1 – 5 and ll. 40 - 60) could also be flowed to the combustor (28).
It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify Roberge with the liquid ammonia fuel, taught by Johnson, because all the claimed elements, i.e., the gas turbine engine having a combustor, the ammonia fuel tank, the main ammonia/fuel line, fuel pump, vaporizer, and gaseous ammonia/fuel line, were known in the art, and one skilled in the art could have substituted the liquid ammonia fuel stored in the ammonia tank, taught by Johnson, for the liquid fuel stored in the cryogenic fuel tank of Roberge, with no change in their respective functions, to yield predictable results, i.e., the liquid ammonia would have been directedly supplied to the combustor of the gas turbine engine as liquid fuel during the startup mode until the gas turbine engine heated up to steady-state operating temperature where the waste heat from the gas turbine engine would have been used to vaporized the liquid ammonia into gaseous ammonia that was then supplied to the combustor of the gas turbine engine as gaseous fuel. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1395; MPEP 2143(B). It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, that the combination of Roberge, i.v., Martz and Johnson, would have taught an ammonia tank, main ammonia line, gaseous ammonia line, liquid ammonia line, etcetera because adding “ammonia” to the name of a structural device did not change the structure or function of the device.
Roberge, i.v., Martz and Johnson, as discussed above, is silent on wherein said control device is configured to determine a flow rate percentage based on the external output request, instruct the flow control valve to adjust the flow rate percentage to be the determined flow rate percentage, and to cause the switching device to implement the first state.
Martz further teaches, in Figs. 1 – 11B, a gas turbine control device (50 – Fig. 1) was configured to receive an external output request (As discussed above, the broadest reasonable interpretation of ‘external output request’ is any external input to the control device that would have resulted in an external output from the gas turbine engine. For example, a start-up signal sent to the control device would have come from an external source, e.g., human operator or external computer network, and would have resulted in the gas turbine generating external output, e.g., hot exhaust, electricity, and/or propulsive thrust. Martz teaches in Fig. 3 – operator panel 102C, Fig. 4 – operator panel 402G, Fig. 6 – starting (1st input to square labeled ‘Select operating mode’ in top left-hand side of figure) and operator load demand (4th input to square labeled ‘Select operating mode’ in top left-hand side of figure), Martz teaches, in Abstract, “A megawatt load control system varies a fuel control signal to govern a detected power output according to a reference value, the fuel control signal determining the flow rate of fuel to a gas turbine”. Martz teaches, in Col. 7, ll. 25 – 30, “an analog startup control included in each of the gas turbine controls 104C and 106C automatically schedules fuel during gas turbine startups”. Martz teaches, in Col. 7, ll. 35 – 45, “In the operator automatic mode, the computers 58G and 100C perform various control functions which provide for automatic startup and automatic loading of the gas and steam turbines under the direction of the operator on a turbine-by-turbine basis”. Martz teaches, in Col. 7, ll. 45 – 55, “Under plant coordinated control, the computer 58G generally directs the plant operation through startup, synchronization and loading to produce the plant power demand”.), said control device (50) is configured to determine a flow rate based on the external output request (Col. 8, ll. 10 – 25, “the turbines are accelerated to synchronous speed, the generators are synchronized and the fuel and steam valves are positioned to operate the turbines at the demand load levels. The manner in which the control system 50 is configured and the manner in which it functions throughout startup and loading depends on the selected plant mode and the selected or forced plant configuration and the real time process behavior”), instruct the flow control valve to adjust the flow rate to be the determined flow rate (Col. 10, ll. 50 – 55, “Generally, once a demand is applied to a load control 424G in the megawatt load control system 400G, the fuel reference is ramped from its present value toward the demand value at a specified rate”. Col. 11, ll. 1 – 10, “…the load reference is proportional to megawatts and becomes a feedforward demand for fuel valve position after conversion from megawatts to valve position…”. Col. 11, ll. 55 – 60, “A fuel control signal is generated on a line 701A of FIG. 7A by the control system 50 (not shown) and the fuel flow to the combustor of the gas turbine 12 is controlled in accordance with the signal on the line 701A”. As shown in Figs. 7B and 10B, fuel control signal 701A ended up controlling the position of fuel valve 709A and/or 717A.), and to cause a switching device to implement the first state (Col. 12, ll. 10 – 30, “The signal on the line 703A has two steady state signal levels, namely, a first signal level corresponding to a numerical zero, in which case the output signal of the multiplier 704A is zero and the combustor of the gas turbine 12 receives a flow of gas, and a second signal level corresponding to a numerical one, in which case the output signal of the multiplier 704A is equal to the fuel control signal on the line 701A, and the combustor of the gas turbine 12 operates solely on oil. … The time of initiation and the ramp rate of such a ramp signal are controlled by a plant operator or by outputs from the control system 50, as schematically illustrated by the input arrows to the transfer ramp generator 702A labeled "operator input" and "control system input."”.).
Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Martz, would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz and Johnson, and the results would have been predictable and readily recognized, that configuring the control device to determine a flow rate based on the external output request, instruct the flow control valve to adjust the flow rate to be the determined flow rate, and to cause the switching device to implement the first state would have facilitated conventional computer control of a dual fuel type gas turbine fuel supply system which supplied a sufficient flow rate of fuel to the gas turbine combustor to satisfy the external output request. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C).
Roberge, i.v., Martz and Johnson, as discussed above, is silent on said flow rate and said determined flow rate being a flow rate percentage and a determined flow rate percentage and silent on said switching device implementing said first state being in response to the determined flow rate percentage of the fuel flowing in the main ammonia line exceeding a predetermined β% that is greater than α% and less than 100%. However, as discussed above, Roberge teaches, in Para. [0025], the first state with only gaseous fuel and no liquid fuel. Roberge Para. [0025] “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.” As discussed above, Roberge teaches, in Para. [0026], the second state being used for the start-up phase of the gas turbine engine. Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”
Martz further teaches, in Fig. 5 (marked-up below), a chart showing the fuel flow (Y-axis) during start-up to full speed no load (FSNL) and then to rated output/load. Martz further teaches, in Col. 10, ll. 20 – 30, “…gas turbine startup in the automatic mode is controlled from an ignition speed of approximately 900 rpm to synchronous speed. At ignition, the fuel reference is set at a fixed value and upon detection of a successful ignition the speed reference is increased to generate an increasing output reference for the fuel control”. Martz further teaches, in Col. 10, ll. 40 – 45, “At the end of the acceleration period, the gas turbine is in a run standby state at a speed of approximately 3,600 rpm and it is ready to be synchronized”. The “standby state at a speed of approximately 3,600 rpm” was known in the gas turbine art as “full speed no load” (FSNL) because the gas turbine was at its full operational speed of 3,600 rpm but was not generating any electricity, i.e., no load. The gas turbine full operational speed was 3,600 rpm to generate alternating current electricity at a frequency of 60 Hertz which was the frequency of the electrical grid in the United States of America. The equation for frequency (f) = (Engine Speed (N) X Number of Poles (P)) / 120, so a 2-pole electric generator had to spin at 3,600 rpm to produce 60 Hz alternating current electricity. Martz further teaches, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”. Martz further teaches, in Col. 18, ll. 45 – 60, “The time duration of fuel transfer is determined by the ramp rate of the transfer ramp signal, i.e. by the time required for the transfer ramp signal to change from one steady state signal level to the other. During the time interval of fuel transfer the fuel control signal associated with the gas turbine for which fuel is transferred may remain constant, or such fuel control signal may be varied by the megawatt load control system in response to a load disturbance or to a change of the megawatt load reference.”.
Mohamed teaches, on Pg. 3, second paragraph, “It requires a certain amount of fuel just to achieve and maintain rated speed (FSNL)”. Mohamed teaches, on Pg. 3, third paragraph, “It usually requires approximately 25% of rated fuel flow-rate just to maintain rated speed (FSNL). … And it requires approximately 75% of rated fuel flow to make power from generator breaker closure (0 MW) to Base Load”. Mohamed teaches, on Pg. 5, fifth paragraph, calculating/determining a flow rate percentage based on an external output request of 150 MegaWatts (MW) for an example gas turbine with a rated output of 245 MegaWatts (MW), maximum fuel flow rate at rated output of 14 kg/second (100% flow rate), 25% fuel flow rate percentage at FSNL (which would be ~3.5 kg/s). The calculation steps were:
Step 1: Calculate the fuel required to produce the incremental load.
First, find the fuel consumed just for power generation (above the FSNL baseline) at the rated load:
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76
438
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Step 2: Determine the proportion of the demanded load to the rated load.
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104
296
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Step 3: Calculate the incremental fuel needed for the demanded load.
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74
480
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Step 4: Add the FSNL fuel back to find the total fuel flow rate for the demanded load.
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76
386
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Step 5: Convert the determined fuel flow rate to flow rate percentage by dividing the determined fuel flow rate by the maximum fuel flow rate at rated output, i.e., maximum fuel flow rate.
9.926 kg/s / 14 kg/s = 0.709 or around 71% flow rate percentage for a output request/demand load of 150 MW.
Marking up Martz – Fig. 5 to show the numerical values in the example gas turbine of Mohamed results in Fig. 5-A shown above.
Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Roberge, Martz, and Mohamed would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz and Johnson, and the results would have been predictable and readily recognized, that configuring said control device to cause said switching device to implement said first state in response to the determined flow rate percentage of the fuel flowing in the main ammonia line exceeding a predetermined β% (shown in Fig. 5-A) that is greater than α% (in this case ~25% at FSNL operating condition) and less than 100% (shown in Fig. 5-A) would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia and then transition from only liquid ammonia (second state) to eventually only gaseous ammonia (first state) at the predetermined β% fuel flow rate which was less than the determined flow rate percentage. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, and Mohamed, said control device would have been configured to receive an external output request (e.g., 150 MW) for the gas turbine, determine a flow rate percentage (e.g., ~71%) based on the external output request, instruct the flow control valve to adjust the flow rate percentage to be the determined flow rate percentage (required to satisfy the external output request), and to cause the switching device (valves) to implement the first state in response to the determined flow rate percentage (e.g., ~71%) of the fuel flowing in the main ammonia line exceeding the predetermined β% that is greater than α% (e.g. 25% at FSNL operating condition) and less than 100% because this was the conventional operating steps/method of conventional gas turbines.
Roberge, i.v., Martz, Johnson, and Mohamed, further teaches including, as shown in Fig. 5-A above, wherein the control device is configured to cause the switching device to implement a third state (labeled in Fig. 5-A), in which both the gaseous ammonia from the gaseous ammonia line and the liquid ammonia from the liquid ammonia line are guided to the combustor (as discussed above both Roberge and Martz taught a transition state where both liquid fuel and gaseous fuel were supplied to the combustor), in response to the determined flow rate percentage of the fuel flowing in the main ammonia line being α% (e.g. 25% at FSNL operating condition) or greater and β% or less (shown in Fig. 5-A), and wherein in the third state (labeled in Fig. 5-A), the flow rate percentage of the liquid ammonia guided to the combustor gradually decreases over time (solid line labeled “Decreasing Liquid fuel”) and the flow rate percentage of the gaseous ammonia guided to the combustor gradually increases over time (dashed line labeled “Increasing Gaseous fuel”). Martz taught, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”. Martz taught, in Col. 18, ll. 45 – 60, “The time duration of fuel transfer is determined by the ramp rate of the transfer ramp signal, i.e. by the time required for the transfer ramp signal to change from one steady state signal level to the other. During the time interval of fuel transfer the fuel control signal associated with the gas turbine for which fuel is transferred may remain constant, or such fuel control signal may be varied by the megawatt load control system in response to a load disturbance or to a change of the megawatt load reference.”. As discussed above, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started-up on only liquid ammonia (second state) and run up to a 25% flow rate percentage of the fuel flowing in the main ammonia line, i.e., α% = 25%, at around 0% of the rated output. At the 25% flow rate percentage of the fuel flowing in the main ammonia line and while increasing the gas turbine engine power output to 61% of the rated output, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started the fuel transfer phase (third state) where both the liquid ammonia and the gaseous ammonia were supplied to the combustor with the flow rate of the gaseous ammonia increasing as the flow rate of the liquid ammonia decreased, until the flow rate percentage of the fuel flowing in the main ammonia line reached around 56%, i.e., β% = 56%, at around 37.5% of the rated output. At β% = 56%, the fuel transfer phase (third state) ended and the first state (only gaseous ammonia supplied to combustor) began.
Roberge, i.v., Martz, Johnson, and Mohamed, as discussed above, is silent on “…or the flow rate percentage of the liquid ammonia guided to the combustor gradually increases over time and the flow rate percentage of the gaseous ammonia guided to the combustor gradually decreases over time”.
Iasillo teaches, in Figs. 1 – 11 (Fig. 6 marked-up above), Abstract, Col. 1, ll. 10 – 21, Col. 3, ll. 40 – 55, and Col. 4, ll. 5 – 35, a similar gas turbine engine (100 – Fig. 1) that switched from a second state (100% liquid fuel, 0% gaseous fuel) guided to the combustor (110), to a third state in which the gaseous fuel flow rate percentage increases over time (X-axis) and the liquid fuel flow rate percentage decreases over time (X-axis) until a first state (0% liquid fuel, 100% gaseous fuel) was reached where only gaseous fuel was guided to the combustor (110), after operating in the first state for a period of time the first state transitions to a different third state in which the gaseous fuel flow rate percentage decreases over time (X-axis) and the liquid fuel flow rate percentage increases over time (X-axis) until the second state (100% liquid fuel, 0% gaseous fuel) was reached so that the liquid/gaseous fuel flow rate percentages were based on the respective fuel flow rates necessary to satisfy the fuel reference demand for a given power output, Col. 8, ll. 10 – 65 and Col. 10, ll. 5 – 60. As evidenced by Ulber, in Para. [0101], ammonia had a lower heating value of 18.6 MJ/kg (MegaJoules per kilogram). The heating value was an inherent material property that refers to the energy released during combustion, which is generally consistent for anhydrous ammonia regardless of its state.
Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Iasillo would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz, Johnson, and Mohamed, and the results would have been predictable and readily recognized, that configuring said control device to cause said switching device to implement said first state in response to the determined flow rate percentage of the fuel flowing in the main ammonia line exceeding the α% (in this case ~25% at FSNL operating condition) would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia. In other words, transitioning from only liquid ammonia (second state) to eventually only gaseous ammonia (first state) by decreasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously increasing the gaseous fuel flow rate percentage over the same time period, then operating the gas turbine in the first state (100% gaseous ammonia) for a period of time until a different third state is started where the transition was from only gaseous ammonia (first state) to eventually only liquid ammonia (second state) by increasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously decreasing the gaseous fuel flow rate percentage over the same time period, as shown in Iasillo – Fig. 6 (marked-up above). Iasillo teaches, in Col. 4, ll. 5 – 35, that during a transfer from one fuel source to another, e.g., liquid fuel to gaseous fuel or vice versa, it was desired that continuity of turbine output power be maintained while minimizing any undershoots or overshoots of output power and temperature. In other words, to maintain a constant exhaust gas temperature and constant gas turbine power output the amount of fuel energy, i.e., the lower heating value, supplied to the combustor during the first state (only gaseous ammonia), second state (only liquid ammonia), and third state (mixture of both gaseous ammonia and liquid ammonia) had to be relatively constant. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate decrease in liquid ammonia guided to the combustor, i.e., less liquid ammonia equals less energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate increase in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same. It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate increase in liquid ammonia guided to the combustor, i.e., more liquid ammonia equals more energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate decrease in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same.
Regarding Claim 28, Roberge teaches, in Figs. 1 and 3, the invention as claimed, including a fuel supply method comprising: vaporizing liquid fuel (in 36 - Para. [0026] – “Exhaust heat exchanger 36 transfers waste heat from exhaust gas to the fuel to vaporize fuel as necessary to drive turbo-generator 14. From exhaust heat exchanger 36, the gaseous fuel is delivered to fuel turbine 38 via fuel line F.”) by heating liquid fuel via heat exchange (in 36) between a heating medium (FE) and at least a part of the liquid fuel supplied from a fuel tank (46); switching a fuel supply state between a plurality of states including a first state (gaseous fuel state – Para. [0024] “Gaseous fuel exiting fuel turbine 38 can be supplied to combustor 24 through fuel line G”.) in which only gaseous fuel, which is fuel vaporized in the vaporizing, is guided to a combustor of a gas turbine as fuel (Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”), and a second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) in which only the liquid fuel, which has not undergone heat exchange with the heating medium in the vaporizing, is guided to the combustor as fuel [Para. [0026] – “Exhaust heat exchanger 36 transfers waste heat from exhaust gas to the fuel to vaporize fuel as necessary to drive turbo-generator 14. From exhaust heat exchanger 36, the gaseous fuel is delivered to fuel turbine 38 via fuel line F.” Obviously during the start-up phase of a gas turbine engine there was no exhaust gas and therefore no waste heat from the exhaust gas to vaporize the liquid fuel into gaseous fuel. Therefore, during the start-up phase of the gas turbine engine of Roberge only liquid fuel was supplied to the combustor because the gaseous fuel had yet to be created by vaporizing the liquid fuel using the hot exhaust gas.]; and controlling of switching [Para. [0016] - “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] - “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation”.] to determine one state from among the plurality of states including the first state and the second state and to implement the one state in the switching, wherein, in the controlling of switching, the fuel supply state is determined to be the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when a flow rate percentage of the liquid fuel supplied from the fuel tank is less than a predetermined α% (any percentage greater than 0% and less than 100%) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the liquid fuel supplied from the fuel tank when the gas turbine is at a rated output [Examiner takes Official Notice that “rated output” of a gas turbine was the maximum power output by that gas turbine when rated at the International Organization for Standardization (ISO) conditions: 15°C/60°F, 60% relative humidity, and 101.3 kPa. Gas turbine power output and thermal efficiency were inversely related to ambient temperature and proportional to ambient pressure, so rating different gas turbine engines at standard ISO conditions was the conventional method of standardizing the operation of different gas turbine engines so their power output could be compared.].
Applicant’s Specification disclosed, in Para. [0038], “The amount of fuel supplied to the gas turbine 10 gradually increases over time during the time period from startup to rated operation. Also, as described above, the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is less than the rated output is less than the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is the rated output. Herein, the fuel flow rate percentage when the output request is the rated output is 100%, and the fuel flow rate percentage before startup is 0%.” Applicant’s Para. [0038] merely describes the conventional operation of gas turbine engines. It was a scientific fact that before startup, i.e., when a gas turbine engine was shut down, the fuel flow rate percentage was 0% because no fuel would have been flowing into the combustion chamber(s) of the gas turbine engine. It was a scientific fact that at rated output operation, i.e., gas turbine engine maximum power output at ISO conditions, the fuel flow rate percentage would have been 100% because outputting maximum rated power, i.e., 100% power output, required the gas turbine to receive and burn the maximum flow rate of fuel, 100% fuel flow rate. Similarly, it was a scientific fact that the amount of fuel supplied to a gas turbine would have gradually increases over time during the time period from startup to rated operation since startup was 0% fuel flow rate and rated operation was 100% fuel flow rate. As evidenced by Martz, in Figs. 5 and 8, Col. 2, ll. 25 – 40, Col. 11, ll. 30 – 35, Col. 13, ll. 50 – 55, and Col. 14, l. 60 to Col. 15, l. 5, fuel flow rate generally linearly increased over time during the time period from startup to rated operation of a gas turbine engine. Martz - Fig. 5 and Col. 10, ll. 20 - 45, showed the minimum fuel flow rate at startup, then the fuel flow rate gradually increased as the gas turbine rotational speed increased to synchronous speed of 3,600 rpm (revolutions per minute). At the synchronous speed the gas turbine started driving a load, in this case an electric generator, and gradually increased the gas turbine power output up to the rated output, in this case 80 Megawatts – Col. 5, ll. 65 – 68, as the fuel flow rate increased to the maximum flow rate of fuel, 100% fuel flow rate. Martz - Fig. 8 and Col. 13, ll. 50 – 55, showed a linear relationship (801) between the gaseous fuel flow rate and the gas turbine power output in Megawatts.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that Roberge teaches wherein, in the controlling of switching, the fuel supply state is determined to be the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when a flow rate percentage of the liquid fuel supplied from the fuel tank is less than a predetermined α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature. Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the liquid fuel supplied from the fuel tank when the gas turbine is at a rated output
Roberge is silent on said liquid fuel being liquid ammonia and said gaseous fuel being gaseous ammonia and the fuel tank being an ammonia tank.
Johnson teaches a similar gas turbine engine (12 – Fig. 1) having liquid fuel being liquid ammonia (NH3 – Col. 2, ll. 50 – 55 “anhydrous liquid ammonia”) stored in an ammonia tank (Fig. 2) where the liquid ammonia (NH3) was directly (36) flowed to the combustor (28) and where gaseous ammonia (26 – Col. 3, ll. 1 – 5 and ll. 40 - 60) could also be flowed to the combustor (28).
It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify Roberge with the liquid ammonia fuel, taught by Johnson, because all the claimed elements, i.e., the gas turbine engine having a combustor, the ammonia fuel tank, the main ammonia/fuel line, fuel pump, vaporizer, and gaseous ammonia/fuel line, were known in the art, and one skilled in the art could have substituted the liquid ammonia fuel stored in the ammonia tank, taught by Johnson, for the liquid fuel stored in the cryogenic fuel tank of Roberge, with no change in their respective functions, to yield predictable results, i.e., the liquid ammonia would have been directedly supplied to the combustor of the gas turbine engine as liquid fuel during the startup mode until the gas turbine engine heated up to steady-state operating temperature where the waste heat from the gas turbine engine would have been used to vaporized the liquid ammonia into gaseous ammonia that was then supplied to the combustor of the gas turbine engine as gaseous fuel. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1395; MPEP 2143(B). It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, that the combination of Roberge, i.v., Martz and Johnson, would have taught an ammonia tank, main ammonia line, gaseous ammonia line, liquid ammonia line, etcetera because adding “ammonia” to the name of a structural device did not change the structure or function of the device.
Roberge, i.v., Martz and Johnson, as discussed above, is silent on wherein, in the controlling of switching, an external output request for the gas turbine is received, a flow rate percentage is determined based on the external output request, and the ammonia supply state is determined to be the first state in response to the determined flow rate percentage of the liquid ammonia supplied from the ammonia tank exceeding the α%. However, as discussed above, Roberge teaches, in Para. [0025], the first state with only gaseous fuel and no liquid fuel. Roberge Para. [0025] “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.” As discussed above, Roberge teaches, in Para. [0026], the second state being used for the start-up phase of the gas turbine engine. Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”
Martz further teaches, in Fig. 5 (marked-up below), a chart showing the fuel flow (Y-axis) during start-up to full speed no load (FSNL) and then to rated output/load. Martz further teaches, in Col. 10, ll. 20 – 30, “…gas turbine startup in the automatic mode is controlled from an ignition speed of approximately 900 rpm to synchronous speed. At ignition, the fuel reference is set at a fixed value and upon detection of a successful ignition the speed reference is increased to generate an increasing output reference for the fuel control”. Martz further teaches, in Col. 10, ll. 40 – 45, “At the end of the acceleration period, the gas turbine is in a run standby state at a speed of approximately 3,600 rpm and it is ready to be synchronized”. The “standby state at a speed of approximately 3,600 rpm” was known in the gas turbine art as “full speed no load” (FSNL) because the gas turbine was at its full operational speed of 3,600 rpm but was not generating any electricity, i.e., no load. The gas turbine full operational speed was 3,600 rpm to generate alternating current electricity at a frequency of 60 Hertz which was the frequency of the electrical grid in the United States of America. The equation for frequency (f) = (Engine Speed (N) X Number of Poles (P)) / 120, so a 2-pole electric generator had to spin at 3,600 rpm to produce 60 Hz alternating current electricity. Martz further teaches, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”.
Mohamed teaches, on Pg. 3, second paragraph, “It requires a certain amount of fuel just to achieve and maintain rated speed (FSNL)”. Mohamed teaches, on Pg. 3, third paragraph, “It usually requires approximately 25% of rated fuel flow-rate just to maintain rated speed (FSNL). … And it requires approximately 75% of rated fuel flow to make power from generator breaker closure (0 MW) to Base Load”. Mohamed teaches, on Pg. 5, fifth paragraph, calculating/determining a flow rate percentage based on an external output request of 150 MegaWatts (MW) for an example gas turbine with a rated output of 245 MegaWatts (MW), maximum fuel flow rate at rated output of 14 kg/second (100% flow rate), 25% fuel flow rate percentage at FSNL (which would be ~3.5 kg/s). The calculation steps were:
Step 1: Calculate the fuel required to produce the incremental load.
First, find the fuel consumed just for power generation (above the FSNL baseline) at the rated load:
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76
438
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Step 2: Determine the proportion of the demanded load to the rated load.
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104
296
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Step 3: Calculate the incremental fuel needed for the demanded load.
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74
480
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Step 4: Add the FSNL fuel back to find the total fuel flow rate for the demanded load.
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76
386
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Step 5: Convert the determined fuel flow rate to flow rate percentage by dividing the determined fuel flow rate by the maximum fuel flow rate at rated output, i.e., maximum fuel flow rate.
9.926 kg/s / 14 kg/s = 0.709 or around 71% flow rate percentage for a output request/demand load of 150 MW.
Marking up Martz – Fig. 5 to show the numerical values in the example gas turbine of Mohamed results in Fig. 5-A shown below.
Thus, improving a particular method (fuel supply), based upon the further teachings of such improvement in Roberge, Martz, and Mohamed would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply method of Roberge, i.v., Martz and Johnson, and the results would have been predictable and readily recognized, that in the controlling of switching, an external output request for the gas turbine is received, a flow rate percentage is determined based on the external output request, and the ammonia supply state is determined to be the first state in response to the determined flow rate percentage of the liquid ammonia supplied from the ammonia tank exceeding the α% (in this case ~25% at FSNL operating condition) would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia and then transition from only liquid ammonia (second state) to eventually only gaseous ammonia (first state). KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, and Mohamed, the controlling of switching, an external output request (e.g., 150 MW) for the gas turbine is received, a flow rate percentage (e.g., ~71%) is determined based on the external output request, and the ammonia supply state is determined to be the first state (shown in Fig. 5-A) in response to the determined flow rate percentage of the liquid ammonia supplied from the ammonia tank exceeding the α% (in this case ~25% at FSNL operating condition) because this was the conventional operating steps/method of conventional gas turbines.
Roberge further teaches, in Para. [0025], wherein, in the controlling of switching, the fuel supply state is determined to be a third state in which both the gaseous fuel, which is the fuel vaporized in the vaporizing, and the liquid fuel, which has not undergone heat exchange with the heating medium in the vaporizing, are guided to the combustor as fuel, in response to the determined flow rate percentage of the liquid fuel supplied from the fuel tank being α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature sufficient to start vaporizing a portion of the liquid fuel into gaseous fuel, e.g., 25% at FSNL operating condition shown in Fig. 5-A above.). Roberge further teaches, in Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of (gaseous) fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.” Martz teaches, in Figs. 7A and 7B, Col. 11, ll. 50 – 55, Col. 12, ll. 5 – 30, and Col. 12, l. 65 to Col. 13, l. 35, a similar gas turbine engine (12 or 22) having a control device (Figs. 7A and 7B) that caused a switching device (709A, 717A, or 709B, 717B) to implement a third state in which both a gaseous fuel from a gaseous fuel line (line from 710A to circle containing an underlined ‘C’) and the liquid fuel from the liquid fuel line (line from 718A and 719A to circle containing an underlined ‘C’) are guided to the combustor (circle containing an underlined ‘C’). Martz teaches, in Col. 12, ll. 20 – 26, “To effect fuel transfer, the output signal of the ramp generator 702A is ramped between the first and second signal levels at a predetermined ramp rate. When the signal on the line 703A is ramped between the first and second signal levels, the combustor of the gas turbine 12 operates on both gas and oil.”
It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, that the combination of Roberge, i.v., Martz, Johnson, and Mohamed, taught in the controlling of switching, the ammonia supply state is determined to be a third state in which both the gaseous ammonia, which is the ammonia vaporized in the vaporizing, and the liquid ammonia, which has not undergone heat exchange with the heating medium in the vaporizing, are guided to the combustor as fuel, in response to the determined flow rate percentage of the liquid fuel supplied from the fuel tank being α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature sufficient to start vaporizing a portion of the liquid fuel into gaseous fuel, e.g., 25% at FSNL operating condition shown in Fig. 5-A above.) because Roberge further teaches, in Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of (gaseous) fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.” As taught by Martz, as the transfer ramp generator signal was ramped from a value of one to a value of zero the liquid fuel signal was decreased while the gaseous fuel signal was increased until the gas turbine engine only received gaseous fuel and the liquid fuel was shut off at the point where the transfer ramp generator signal value was zero. During the fuel transfer the sum of the liquid fuel signal and the gaseous fuel signal equaled the fuel control signal.
Roberge, i.v., Martz, Johnson, and Mohamed, further teaches including, as shown in Fig. 5-A above, wherein the control device is configured to cause the switching device to implement a third state (labeled in Fig. 5-A), in which both the gaseous ammonia from the gaseous ammonia line and the liquid ammonia from the liquid ammonia line are guided to the combustor (as discussed above both Roberge and Martz taught a transition state where both liquid fuel and gaseous fuel were supplied to the combustor), in response to the determined flow rate percentage of the fuel flowing in the main ammonia line being α% (e.g. 25% at FSNL operating condition) or greater and β% or less (shown in Fig. 5-A), and wherein in the third state (labeled in Fig. 5-A), the flow rate percentage of the liquid ammonia guided to the combustor gradually decreases over time (solid line labeled “Decreasing Liquid fuel”) and the flow rate percentage of the gaseous ammonia guided to the combustor gradually increases over time (dashed line labeled “Increasing Gaseous fuel”). Martz taught, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”. Martz taught, in Col. 18, ll. 45 – 60, “The time duration of fuel transfer is determined by the ramp rate of the transfer ramp signal, i.e. by the time required for the transfer ramp signal to change from one steady state signal level to the other. During the time interval of fuel transfer the fuel control signal associated with the gas turbine for which fuel is transferred may remain constant, or such fuel control signal may be varied by the megawatt load control system in response to a load disturbance or to a change of the megawatt load reference.”. As discussed above, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started-up on only liquid ammonia (second state) and run up to a 25% flow rate percentage of the fuel flowing in the main ammonia line, i.e., α% = 25%, at around 0% of the rated output. At the 25% flow rate percentage of the fuel flowing in the main ammonia line and while increasing the gas turbine engine power output to 61% of the rated output, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started the fuel transfer phase (third state) where both the liquid ammonia and the gaseous ammonia were supplied to the combustor with the flow rate of the gaseous ammonia increasing as the flow rate of the liquid ammonia decreased, until the flow rate percentage of the fuel flowing in the main ammonia line reached around 56%, i.e., β% = 56%, at around 37.5% of the rated output. At β% = 56%, the fuel transfer phase (third state) ended and the first state (only gaseous ammonia supplied to combustor) began.
Roberge, i.v., Martz, Johnson, and Mohamed, as discussed above, is silent on “…or the flow rate percentage of the liquid ammonia guided to the combustor gradually increases over time and the flow rate percentage of the gaseous ammonia guided to the combustor gradually decreases over time”.
Iasillo teaches, in Figs. 1 – 11 (Fig. 6 marked-up above), Abstract, Col. 1, ll. 10 – 21, Col. 3, ll. 40 – 55, and Col. 4, ll. 5 – 35, a similar gas turbine engine (100 – Fig. 1) that switched from a second state (100% liquid fuel, 0% gaseous fuel) guided to the combustor (110), to a third state in which the gaseous fuel flow rate percentage increases over time (X-axis) and the liquid fuel flow rate percentage decreases over time (X-axis) until a first state (0% liquid fuel, 100% gaseous fuel) was reached where only gaseous fuel was guided to the combustor (110), after operating in the first state for a period of time the first state transitions to a different third state in which the gaseous fuel flow rate percentage decreases over time (X-axis) and the liquid fuel flow rate percentage increases over time (X-axis) until the second state (100% liquid fuel, 0% gaseous fuel) was reached so that the liquid/gaseous fuel flow rate percentages were based on the respective fuel flow rates necessary to satisfy the fuel reference demand for a given power output, Col. 8, ll. 10 – 65 and Col. 10, ll. 5 – 60. As evidenced by Ulber, in Para. [0101], ammonia had a lower heating value of 18.6 MJ/kg (MegaJoules per kilogram). The heating value was an inherent material property that refers to the energy released during combustion, which is generally consistent for anhydrous ammonia regardless of its state.
Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Iasillo would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz, Johnson, and Mohamed, and the results would have been predictable and readily recognized, that configuring said control device to cause said switching device to implement said first state in response to the determined flow rate percentage of the fuel flowing in the main ammonia line exceeding the α% (in this case ~25% at FSNL operating condition) would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia. In other words, transitioning from only liquid ammonia (second state) to eventually only gaseous ammonia (first state) by decreasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously increasing the gaseous fuel flow rate percentage over the same time period, then operating the gas turbine in the first state (100% gaseous ammonia) for a period of time until a different third state is started where the transition was from only gaseous ammonia (first state) to eventually only liquid ammonia (second state) by increasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously decreasing the gaseous fuel flow rate percentage over the same time period, as shown in Iasillo – Fig. 6 (marked-up above). Iasillo teaches, in Col. 4, ll. 5 – 35, that during a transfer from one fuel source to another, e.g., liquid fuel to gaseous fuel or vice versa, it was desired that continuity of turbine output power be maintained while minimizing any undershoots or overshoots of output power and temperature. In other words, to maintain a constant exhaust gas temperature and constant gas turbine power output the amount of fuel energy, i.e., the lower heating value, supplied to the combustor during the first state (only gaseous ammonia), second state (only liquid ammonia), and third state (mixture of both gaseous ammonia and liquid ammonia) had to be relatively constant. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate decrease in liquid ammonia guided to the combustor, i.e., less liquid ammonia equals less energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate increase in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same. It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate increase in liquid ammonia guided to the combustor, i.e., more liquid ammonia equals more energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate decrease in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same.
Regarding Claim 31, Roberge teaches, in Figs. 1 and 3, the invention as claimed, including a fuel supply method comprising: vaporizing liquid fuel (in 36 - Para. [0026] – “Exhaust heat exchanger 36 transfers waste heat from exhaust gas to the fuel to vaporize fuel as necessary to drive turbo-generator 14. From exhaust heat exchanger 36, the gaseous fuel is delivered to fuel turbine 38 via fuel line F.”) by heating liquid fuel via heat exchange (in 36) between a heating medium (FE) and at least a part of the liquid fuel supplied from a fuel tank (46); switching a fuel supply state between a plurality of states including a first state (gaseous fuel state – Para. [0024] “Gaseous fuel exiting fuel turbine 38 can be supplied to combustor 24 through fuel line G”.) in which only gaseous fuel, which is fuel vaporized in the vaporizing, is guided to a combustor of a gas turbine as fuel (Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”), and a second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) in which only the liquid fuel, which has not undergone heat exchange with the heating medium in the vaporizing, is guided to the combustor as fuel [Para. [0026] – “Exhaust heat exchanger 36 transfers waste heat from exhaust gas to the fuel to vaporize fuel as necessary to drive turbo-generator 14. From exhaust heat exchanger 36, the gaseous fuel is delivered to fuel turbine 38 via fuel line F.” Obviously during the start-up phase of a gas turbine engine there was no exhaust gas and therefore no waste heat from the exhaust gas to vaporize the liquid fuel into gaseous fuel. Therefore, during the start-up phase of the gas turbine engine of Roberge only liquid fuel was supplied to the combustor because the gaseous fuel had yet to be created by vaporizing the liquid fuel using the hot exhaust gas.]; and controlling of switching [Para. [0016] - “A plurality of valved fuel lines A-E can be used to control the flow of fuel through system 10 via controller 48.” Para. [0024] - “Controller 48 can be used to regulate the amount of fuel delivered to combustor 24 to maintain optimum operation”.] to determine one state from among the plurality of states including the first state and the second state and to implement the one state in the switching, wherein, in the controlling of switching, the fuel supply state is determined to be the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when a flow rate percentage of the liquid fuel supplied from the fuel tank is less than a predetermined α% (any percentage greater than 0% and less than 100%) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the liquid fuel supplied from the fuel tank when the gas turbine is at a rated output [Examiner takes Official Notice that “rated output” of a gas turbine was the maximum power output by that gas turbine when rated at the International Organization for Standardization (ISO) conditions: 15°C/60°F, 60% relative humidity, and 101.3 kPa. Gas turbine power output and thermal efficiency were inversely related to ambient temperature and proportional to ambient pressure, so rating different gas turbine engines at standard ISO conditions was the conventional method of standardizing the operation of different gas turbine engines so their power output could be compared.].
Applicant’s Specification disclosed, in Para. [0038], “The amount of fuel supplied to the gas turbine 10 gradually increases over time during the time period from startup to rated operation. Also, as described above, the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is less than the rated output is less than the flow rate of the fuel supplied to the combustor 15 in a case in which the output request is the rated output. Herein, the fuel flow rate percentage when the output request is the rated output is 100%, and the fuel flow rate percentage before startup is 0%.” Applicant’s Para. [0038] merely describes the conventional operation of gas turbine engines. It was a scientific fact that before startup, i.e., when a gas turbine engine was shut down, the fuel flow rate percentage was 0% because no fuel would have been flowing into the combustion chamber(s) of the gas turbine engine. It was a scientific fact that at rated output operation, i.e., gas turbine engine maximum power output at ISO conditions, the fuel flow rate percentage would have been 100% because outputting maximum rated power, i.e., 100% power output, required the gas turbine to receive and burn the maximum flow rate of fuel, 100% fuel flow rate. Similarly, it was a scientific fact that the amount of fuel supplied to a gas turbine would have gradually increases over time during the time period from startup to rated operation since startup was 0% fuel flow rate and rated operation was 100% fuel flow rate. As evidenced by Martz, in Figs. 5 and 8, Col. 2, ll. 25 – 40, Col. 11, ll. 30 – 35, Col. 13, ll. 50 – 55, and Col. 14, l. 60 to Col. 15, l. 5, fuel flow rate generally linearly increased over time during the time period from startup to rated operation of a gas turbine engine. Martz - Fig. 5 and Col. 10, ll. 20 - 45, showed the minimum fuel flow rate at startup, then the fuel flow rate gradually increased as the gas turbine rotational speed increased to synchronous speed of 3,600 rpm (revolutions per minute). At the synchronous speed the gas turbine started driving a load, in this case an electric generator, and gradually increased the gas turbine power output up to the rated output, in this case 80 Megawatts – Col. 5, ll. 65 – 68, as the fuel flow rate increased to the maximum flow rate of fuel, 100% fuel flow rate. Martz - Fig. 8 and Col. 13, ll. 50 – 55, showed a linear relationship (801) between the gaseous fuel flow rate and the gas turbine power output in Megawatts.
It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that Roberge teaches wherein, in the controlling of switching, the fuel supply state is determined to be the second state (start-up phase – Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”) when a flow rate percentage of the liquid fuel supplied from the fuel tank is less than a predetermined α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature. Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”) that is greater than 0% and less than 100%, with 100% being the flow rate percentage of the liquid fuel supplied from the fuel tank when the gas turbine is at a rated output
Roberge is silent on said liquid fuel being liquid ammonia and said gaseous fuel being gaseous ammonia and the fuel tank being an ammonia tank.
Johnson teaches a similar gas turbine engine (12 – Fig. 1) having liquid fuel being liquid ammonia (NH3 – Col. 2, ll. 50 – 55 “anhydrous liquid ammonia”) stored in an ammonia tank (Fig. 2) where the liquid ammonia (NH3) was directly (36) flowed to the combustor (28) and where gaseous ammonia (26 – Col. 3, ll. 1 – 5 and ll. 40 - 60) could also be flowed to the combustor (28).
It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, to modify Roberge with the liquid ammonia fuel, taught by Johnson, because all the claimed elements, i.e., the gas turbine engine having a combustor, the ammonia fuel tank, the main ammonia/fuel line, fuel pump, vaporizer, and gaseous ammonia/fuel line, were known in the art, and one skilled in the art could have substituted the liquid ammonia fuel stored in the ammonia tank, taught by Johnson, for the liquid fuel stored in the cryogenic fuel tank of Roberge, with no change in their respective functions, to yield predictable results, i.e., the liquid ammonia would have been directedly supplied to the combustor of the gas turbine engine as liquid fuel during the startup mode until the gas turbine engine heated up to steady-state operating temperature where the waste heat from the gas turbine engine would have been used to vaporized the liquid ammonia into gaseous ammonia that was then supplied to the combustor of the gas turbine engine as gaseous fuel. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1395; MPEP 2143(B). It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, that the combination of Roberge, i.v., Martz and Johnson, would have taught an ammonia tank, main ammonia line, gaseous ammonia line, liquid ammonia line, etcetera because adding “ammonia” to the name of a structural device did not change the structure or function of the device.
Roberge, i.v., Martz and Johnson, as discussed above, is silent on wherein, in the controlling of switching, an external output request for the gas turbine is received, a flow rate percentage is determined based on the external output request, and the ammonia supply state is determined to be the first state in response to the determined flow rate percentage of the liquid ammonia supplied from the ammonia tank exceeding a predetermined β% that is greater than α% and less than 100%. However, as discussed above, Roberge teaches, in Para. [0025], the first state with only gaseous fuel and no liquid fuel. Roberge Para. [0025] “As the engine operates and available fuel heating sources increase, a portion of fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.” As discussed above, Roberge teaches, in Para. [0026], the second state being used for the start-up phase of the gas turbine engine. Para. [0026] “During engine startup, liquid fuel may be supplied directly to combustor 24 through fuel line B.”
Martz further teaches, in Fig. 5, a chart showing the fuel flow (Y-axis) during start-up to full speed no load (FSNL) and then to rated output/load. Martz further teaches, in Col. 10, ll. 20 – 30, “…gas turbine startup in the automatic mode is controlled from an ignition speed of approximately 900 rpm to synchronous speed. At ignition, the fuel reference is set at a fixed value and upon detection of a successful ignition the speed reference is increased to generate an increasing output reference for the fuel control”. Martz further teaches, in Col. 10, ll. 40 – 45, “At the end of the acceleration period, the gas turbine is in a run standby state at a speed of approximately 3,600 rpm and it is ready to be synchronized”. The “standby state at a speed of approximately 3,600 rpm” was known in the gas turbine art as “full speed no load” (FSNL) because the gas turbine was at its full operational speed of 3,600 rpm but was not generating any electricity, i.e., no load. The gas turbine full operational speed was 3,600 rpm to generate alternating current electricity at a frequency of 60 Hertz which was the frequency of the electrical grid in the United States Patent of America. The equation for frequency (f) = (Engine Speed (N) X Number of Poles (P)) / 120, so a 2-pole electric generator had to spin at 3,600 rpm to produce 60 Hz alternating current electricity. Martz further teaches, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”.
Mohamed teaches, on Pg. 3, second paragraph, “It requires a certain amount of fuel just to achieve and maintain rated speed (FSNL)”. Mohamed teaches, on Pg. 3, third paragraph, “It usually requires approximately 25% of rated fuel flow-rate just to maintain rated speed (FSNL). … And it requires approximately 75% of rated fuel flow to make power from generator breaker closure (0 MW) to Base Load”. Mohamed teaches, on Pg. 5, fifth paragraph, calculating/determining a flow rate percentage based on an external output request of 150 MegaWatts (MW) for an example gas turbine with a rated output of 245 MegaWatts (MW), maximum fuel flow rate at rated output of 14 kg/second (100% flow rate), 25% fuel flow rate percentage at FSNL (which would be ~3.5 kg/s). The calculation steps were:
Step 1: Calculate the fuel required to produce the incremental load.
First, find the fuel consumed just for power generation (above the FSNL baseline) at the rated load:
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76
438
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Step 2: Determine the proportion of the demanded load to the rated load.
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104
296
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Step 3: Calculate the incremental fuel needed for the demanded load.
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74
480
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Step 4: Add the FSNL fuel back to find the total fuel flow rate for the demanded load.
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76
386
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Step 5: Convert the determined fuel flow rate to flow rate percentage by dividing the determined fuel flow rate by the maximum fuel flow rate at rated output, i.e., maximum fuel flow rate.
9.926 kg/s / 14 kg/s = 0.709 or around 71% flow rate percentage for a output request/demand load of 150 MW.
Marking up Martz – Fig. 5 to show the numerical values in the example gas turbine of Mohamed results in Fig. 5-A shown below.
Thus, improving a particular method (fuel supply), based upon the further teachings of such improvement in Roberge, Martz, and Mohamed would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply method of Roberge, i.v., Martz and Johnson, and the results would have been predictable and readily recognized, that in the controlling of switching, an external output request for the gas turbine is received, a flow rate percentage is determined based on the external output request, and the ammonia supply state is determined to be the first state in response to the determined flow rate percentage of the liquid ammonia supplied from the ammonia tank exceeding a predetermined β% that is greater than α% (in this case ~25% at FSNL operating condition) and less than 100% would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia and then transition from only liquid ammonia (second state) to eventually only gaseous ammonia (first state) starting at the predetermined β% fuel flow rate. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, and Mohamed, the controlling of switching, an external output request (e.g., 150 MW) for the gas turbine is received, a flow rate percentage (e.g., ~71%) is determined based on the external output request, and the ammonia supply state is determined to be the first state (shown in Fig. 5-A) in response to the determined flow rate percentage of the liquid ammonia supplied from the ammonia tank exceeding a predetermined β% (shown in Fig. 5-A) that is greater than α% (in this case ~25% at FSNL operating condition) and less than 100% because this was the conventional operating steps/method of conventional gas turbines.
Roberge further teaches, in Para. [0025], wherein, in the controlling of switching, the fuel supply state is determined to be a third state in which both the gaseous fuel, which is the fuel vaporized in the vaporizing, and the liquid fuel, which has not undergone heat exchange with the heating medium in the vaporizing, are guided to the combustor as fuel, in response to the determined flow rate percentage of the liquid fuel supplied from the fuel tank being α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature sufficient to start vaporizing a portion of the liquid fuel into gaseous fuel, e.g., 25% at FSNL operating condition shown in Fig. 5-A above.) or greater and β% or less. Roberge further teaches, in Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of (gaseous) fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.”
Martz teaches, in Figs. 7A and 7B, Col. 11, ll. 50 – 55, Col. 12, ll. 5 – 30, and Col. 12, l. 65 to Col. 13, l. 35, a similar gas turbine engine (12 or 22) having a control device (Figs. 7A and 7B) that caused a switching device (709A, 717A, or 709B, 717B) to implement a third state in which both a gaseous fuel from a gaseous fuel line (line from 710A to circle containing an underlined ‘C’) and the liquid fuel from the liquid fuel line (line from 718A and 719A to circle containing an underlined ‘C’) are guided to the combustor (circle containing an underlined ‘C’). Martz teaches, in Col. 12, ll. 20 – 26, “To effect fuel transfer, the output signal of the ramp generator 702A is ramped between the first and second signal levels at a predetermined ramp rate. When the signal on the line 703A is ramped between the first and second signal levels, the combustor of the gas turbine 12 operates on both gas and oil.” As discussed above, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started-up on only liquid ammonia (second state) and run up to a 25% flow rate percentage of the fuel flowing in the main ammonia line, i.e., α% = 25%, at around 0% of the rated output. At the 25% flow rate percentage of the fuel flowing in the main ammonia line and while increasing the gas turbine engine power output to 61% of the rated output, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started the fuel transfer phase (third state) where both the liquid ammonia and the gaseous ammonia were supplied to the combustor with the flow rate of the gaseous ammonia increasing as the flow rate of the liquid ammonia decreased, until the flow rate percentage of the fuel flowing in the main ammonia line reached around 56%, i.e., β% = 56%, at around 37.5% of the rated output. At β% = 56%, the fuel transfer phase (third state) ended and the first state (only gaseous ammonia supplied to combustor) began.
It would have been obvious, to one of ordinary skill in the art, before the effective filing date of the claimed invention, that the combination of Roberge, i.v., Martz, Johnson, and Mohamed, taught in the controlling of switching, the ammonia supply state is determined to be a third state in which both the gaseous ammonia, which is the ammonia vaporized in the vaporizing, and the liquid ammonia, which has not undergone heat exchange with the heating medium in the vaporizing, are guided to the combustor as fuel, in response to the determined flow rate percentage of the liquid fuel supplied from the fuel tank being α% (any percentage greater than 0% and less than 100%, for example the flow rate percentage after start-up where the gas turbine engine had achieved steady-state operational temperature sufficient to start vaporizing a portion of the liquid fuel into gaseous fuel, e.g., 25% at FSNL operating condition shown in Fig. 5-A above.) or greater and β% or less because Roberge further teaches, in Para. [0025] – “As the engine operates and available fuel heating sources increase, a portion of (gaseous) fuel flow can be gradually increased through line C described above and eventually transitioned such that no liquid phase fuel is supplied to combustor 24.” As taught by Martz, as the transfer ramp generator signal was ramped from a value of one to a value of zero the liquid fuel signal was decreased while the gaseous fuel signal was increased until the gas turbine engine only received gaseous fuel and the liquid fuel was shut off at the point where the transfer ramp generator signal value was zero. During the fuel transfer the sum of the liquid fuel signal and the gaseous fuel signal equaled the fuel control signal.
Roberge, i.v., Martz, Johnson, and Mohamed, further teaches including, as shown in Fig. 5-A above, wherein the control device is configured to cause the switching device to implement a third state (labeled in Fig. 5-A), in which both the gaseous ammonia from the gaseous ammonia line and the liquid ammonia from the liquid ammonia line are guided to the combustor (as discussed above both Roberge and Martz taught a transition state where both liquid fuel and gaseous fuel were supplied to the combustor), in response to the determined flow rate percentage of the fuel flowing in the main ammonia line being α% (e.g. 25% at FSNL operating condition) or greater and β% or less (shown in Fig. 5-A), and wherein in the third state (labeled in Fig. 5-A), the flow rate percentage of the liquid ammonia guided to the combustor gradually decreases over time (solid line labeled “Decreasing Liquid fuel”) and the flow rate percentage of the gaseous ammonia guided to the combustor gradually increases over time (dashed line labeled “Increasing Gaseous fuel”). Martz taught, in Col. 15, ll. 14 – 25, “During fuel transfer, the signal on the line 703A is ramped between the steady state signal levels corresponding to numerical zero and numerical one. while the signal on the line 703A is ramped, the fuel control signal is split into an oil control signal on the line 705A and a gas control signal on the line 707A, with the result that the combustor of the gas turbine 12 operates on both oil (liquid) and gas during fuel transfer.”. Martz taught, in Col. 18, ll. 45 – 60, “The time duration of fuel transfer is determined by the ramp rate of the transfer ramp signal, i.e. by the time required for the transfer ramp signal to change from one steady state signal level to the other. During the time interval of fuel transfer the fuel control signal associated with the gas turbine for which fuel is transferred may remain constant, or such fuel control signal may be varied by the megawatt load control system in response to a load disturbance or to a change of the megawatt load reference.”. As discussed above, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started-up on only liquid ammonia (second state) and run up to a 25% flow rate percentage of the fuel flowing in the main ammonia line, i.e., α% = 25%, at around 0% of the rated output. At the 25% flow rate percentage of the fuel flowing in the main ammonia line and while increasing the gas turbine engine power output to 61% of the rated output, the gas turbine engine of Roberge, i.v., Martz, Johnson, and Mohamed, would have started the fuel transfer phase (third state) where both the liquid ammonia and the gaseous ammonia were supplied to the combustor with the flow rate of the gaseous ammonia increasing as the flow rate of the liquid ammonia decreased, until the flow rate percentage of the fuel flowing in the main ammonia line reached around 56%, i.e., β% = 56%, at around 37.5% of the rated output. At β% = 56%, the fuel transfer phase (third state) ended and the first state (only gaseous ammonia supplied to combustor) began.
Roberge, i.v., Martz, Johnson, and Mohamed, as discussed above, is silent on “…or the flow rate percentage of the liquid ammonia guided to the combustor gradually increases over time and the flow rate percentage of the gaseous ammonia guided to the combustor gradually decreases over time”.
Iasillo teaches, in Figs. 1 – 11 (Fig. 6 marked-up above), Abstract, Col. 1, ll. 10 – 21, Col. 3, ll. 40 – 55, and Col. 4, ll. 5 – 35, a similar gas turbine engine (100 – Fig. 1) that switched from a second state (100% liquid fuel, 0% gaseous fuel) guided to the combustor (110), to a third state in which the gaseous fuel flow rate percentage increases over time (X-axis) and the liquid fuel flow rate percentage decreases over time (X-axis) until a first state (0% liquid fuel, 100% gaseous fuel) was reached where only gaseous fuel was guided to the combustor (110), after operating in the first state for a period of time the first state transitions to a different third state in which the gaseous fuel flow rate percentage decreases over time (X-axis) and the liquid fuel flow rate percentage increases over time (X-axis) until the second state (100% liquid fuel, 0% gaseous fuel) was reached so that the liquid/gaseous fuel flow rate percentages were based on the respective fuel flow rates necessary to satisfy the fuel reference demand for a given power output, Col. 8, ll. 10 – 65 and Col. 10, ll. 5 – 60. As evidenced by Ulber, in Para. [0101], ammonia had a lower heating value of 18.6 MJ/kg (MegaJoules per kilogram). The heating value was an inherent material property that refers to the energy released during combustion, which is generally consistent for anhydrous ammonia regardless of its state.
Thus, improving a particular system (fuel supply system), based upon the further teachings of such improvement in Iasillo would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, i.e., applying these known improvement techniques in the same manner to the fuel supply system of Roberge, i.v., Martz, Johnson, and Mohamed, and the results would have been predictable and readily recognized, that configuring said control device to cause said switching device to implement said first state in response to the determined flow rate percentage of the fuel flowing in the main ammonia line exceeding the α% (in this case ~25% at FSNL operating condition) would have facilitated starting the transition from liquid fuel to gaseous fuel after the gas turbine had reached a stable operating condition (in this case FSNL operating condition) where there was sufficient waste heat available to start heating the liquid ammonia into gaseous ammonia. In other words, transitioning from only liquid ammonia (second state) to eventually only gaseous ammonia (first state) by decreasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously increasing the gaseous fuel flow rate percentage over the same time period, then operating the gas turbine in the first state (100% gaseous ammonia) for a period of time until a different third state is started where the transition was from only gaseous ammonia (first state) to eventually only liquid ammonia (second state) by increasing the liquid fuel flow rate percentage over time (X-axis) while simultaneously decreasing the gaseous fuel flow rate percentage over the same time period, as shown in Iasillo – Fig. 6 (marked-up above). Iasillo teaches, in Col. 4, ll. 5 – 35, that during a transfer from one fuel source to another, e.g., liquid fuel to gaseous fuel or vice versa, it was desired that continuity of turbine output power be maintained while minimizing any undershoots or overshoots of output power and temperature. In other words, to maintain a constant exhaust gas temperature and constant gas turbine power output the amount of fuel energy, i.e., the lower heating value, supplied to the combustor during the first state (only gaseous ammonia), second state (only liquid ammonia), and third state (mixture of both gaseous ammonia and liquid ammonia) had to be relatively constant. KSR, 550 U.S. 398 (2007), 82 USPQ2d at 1396; MPEP 2143(C). It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate decrease in liquid ammonia guided to the combustor, i.e., less liquid ammonia equals less energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate increase in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same. It would have been obvious to one of ordinary skill in the art, before the effective filing date of the claimed invention, that in the combination of Roberge, i.v., Martz, Johnson, Mohamed, and Iasillo, as evidenced by Ulber, to maintain the power output by the gas turbine during third state operations every unit mass flow rate increase in liquid ammonia guided to the combustor, i.e., more liquid ammonia equals more energy released from liquid ammonia during combustion, would have had be compensated for by an equivalent unit mass flow rate decrease in gaseous ammonia guided to the combustor since the lower heating value of liquid ammonia and gaseous ammonia were about the same.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Response to Arguments
Applicant's arguments filed 02/02/2026 have been fully considered and to the extent possible have been addressed in the rejections above, at the appropriate locations.
Correspondence
Any inquiry concerning this communication or earlier communications from the examiner should be directed to LORNE E MEADE whose telephone number is (571)270-7570. The examiner can normally be reached Monday - Friday 8-5 EST.
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/LORNE E MEADE/Primary Examiner, Art Unit 3741
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