DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 1-8 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 1 is written as a run-on sentence with many commas and “ands” and no semi-colons to help break up the claim language in a grammatically correct way. This renders the claim entirely unclear as it is unclear how each portion of the claim relates to the other portions.
Claim 1 states “the natural gas to be liquefied” which is found to be indefinite as it is unclear if this is referring to the pre-treated natural gas, or the natural gas pre-cooled.
Claim 1 states “heat of compression is removed, the natural gas is pre-cooled in multiple stages”, it is unclear how the heat of compression is removed and if that is occurring before pre-cooling or due to the pre-cooling.
Claim 1 states “gas that failed to liquefy” which is found to be indefinite as it is unclear how this gas relates to the previously claimed streams.
Claim 1 states “re-used in multi-stage pre-cooling of the natural gas” which is found indefinite as it is unclear how this is related to the previous disclosed “pre-cooled in multiple stages” earlier in the claim.
Claim 1 states “the first stream” and “the second stream” both of which lack antecedent basis.
Claim 1 states “it” which is found to be indefinite (line 10) and “its” (line 1 of page 4)
Claim 1 states “used as a single stream of the low-pressure light refrigerant for cooling the natural gas, the second stream of the light refrigerant before its isenthalpic expansion and evaporation and cooling the single stream of the high pressure light refrigerant” which is found to be unclear as to what is meant by this limitation. It appears it may be trying to say the combined single stream cools the natural gas, the second stream of the light refrigerant, and the high-pressure light refrigerant but it is unclear.
The claim as best interpreted is rejected under prior art rejections below.
Claim 5 states “wherein the pressure of the natural gas to be liquefied after sub-cooling by way of recovering cold vapor of the light refrigerant is additionally reduced to pressure which excludes formation of a two-phase flow”, which is found to be indefinite as it is unclear what is meant by excluding formation of a two-phase flow or for how long would two-phase flow be excluded indefinitely and how so assuming ambient heating and other downstream process changes such as boil-off.
Claims 2-5 depend from claim 1 above and therefore inherit the 35 USC 112 deficiencies of their parent claim.
Claim 6 states “The first pressure reducer” (line 6) which lacks antecedent basis.
Claim 6 states “at least one air cooler or water cooler and inter-tube spaces of the heavy refrigerant vaporizers” it is unclear if the vaporizes are being claimed separately from the air cooler OR water cooler, or if the way it is claimed is air cooler OR a water cooler and vaporizers.
Claim 6 states “outlets of which” which is found to be indefinite as it is unclear what prior structure “which” is referring to.
Claims 7-8 depend from claim 6 and inherit the 35 USC 112 deficiencies of their parent claims.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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 1-8 are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent number 4,809,154 Newton in view of U.S. patent publication number 2019/0331413 Krishnamurthy et al. (hereinafter Krishnamurthy).
Regarding claim 1, Newton discloses a natural gas liquefaction method (figure 1, incorporating US 3,763,658 reference numbers) by which pre-treated natural gas is compressed (line 10 is a feed after carbon dioxide impurities have been removed at a pressure of 735 psia), heat of compression is removed (12), the natural gas is pre-cooled in multiple stages (12/24/36) by way of evaporating heavy refrigerant (from 62/64/65, see refrigerant cycle, liquid refrigerant is vaporized and returned to compressor 62), sub-cooled by way of recovering cold from light refrigerant vapors and preliminary evaporation (subcooled through 47/55/54/58), the natural gas to be liquefied is depressurized in 58, gas that failed to liquefy is separated (in 154) and liquefied gas is removed 156, while the heavy refrigerant obtained by evaporation is compressed, condensed, and re-used in multi-stage pre-cooling of the natural gas (62/64/65 expanded in 66/79/80/81 used in 12/24/36), and the light refrigerant is compressed 100/102, cooled 86/88/89/122/114, and used for sub-cooling the natural gas (in 47/48/54), wherein the light refrigerant is compressed 100/102 before cooling, heat of compression is removed (104/106), followed by consecutive cooling of it with low- pressure light refrigerant and evaporating heavy refrigerant (86/88/89, cooled against heavy, and then cooled against light in 122/114/124), followed by separation of high-pressure light refrigerant into two streams 112/120 with an expansion of the first stream 116 and consecutive cooling 114, isenthalpic expansion 116/128, and evaporation of the second stream through sub-cooling of the natural gas (through nozzles at 130/56 subcools gas coming from 55), followed by the streams being mixed together (within shell side of the heat exchanger surrounding 114/122/48/47) at equal pressure and used as a single stream of the low-pressure light refrigerant for cooling the natural gas, the second stream of the light refrigerant before its isenthalpic expansion and evaporation, and cooling the single stream of the high pressure light refrigerant. Newton does not disclose consecutive cooling with low-pressure light refrigerant prior to the separation into multiple streams and does not disclose isentropic expansion. Krishnamurthy discloses cooling light refrigerant upstream of splitting by the light refrigerant itself (well known in the art as an interchanger; see figure 3, interchanger 197 wherein light refrigerant 171 cools light refrigerant in 160 prior to splitting into 169/170). It would have been obvious to one of ordinary skill in the art at the time of applicant’s filing to utilize the light refrigerant to help precool the light refrigerant in an upstream interchanger as disclosed by Krishnamurthy with the natural gas liquefaction of Newton in order to take advantage of any remaining waste heat and to also ensure vaporization of the returning light refrigerant prior to compression. Krishnamurthy further discloses isentropic expansion (see turbines 164 or 172). It would have been obvious to one of ordinary skill in the art at the time of applicant’s filing to utilize a turbine for one of the refrigerant streams as this involves a simple substitution of one known expansion device (turbine) for another (expansion valve) and would provide power to help power compressors providing energy savings within the liquefaction plant.
Regarding claim 2, Newton (figure 1) discloses wherein the multi-stage pre-cooling of the natural gas is carried out at different levels of the heavy refrigerant boiling pressure in stages that are provided by reducing pressure of the heavy refrigerant to boiling before each stage, and at least the last stage is used for cooling the high-pressure light refrigerant (see 12/24/36/86/88/89, expansion in 66/79/80/81/92/94/96, last stage 89 cools light refrigerant).
Regarding claim 3, Krishnamurthy further discloses wherein energy released from isentropic expansion of the first stream is used for compressing the light refrigerant (paragraph 86).
Regarding claim 4, Newton discloses wherein nitrogen is used as the light refrigerant (see column 1, line 10; see figure 1, composition modified by N2 through 142a). Newton does not explicitly disclose ethane or ethylene is used as the heavy refrigerant instead providing a propane refrigerant as the upstream cooling circuit. The examiner goes on official notice that ethane or ethylene is a well known refrigerant for cooling natural gas in a natural gas liquefaction plant. Newton clearly provides ethane as a possible component already in the downstream refrigerant cycle (C2 in 142c). It would have been obvious to one of ordinary skill in the art at the time of applicant’s filing to utilize ethane as the heavy refrigerant in Newton as a simple substitution of one well know refrigerant for another based on a design choice that can be optimized through routine experimentation both by availability of the refrigerant, cost, and also the specific temperature profiles attempting to be achieved.
Regarding claim 5, As best understood, Newton discloses wherein the pressure of the natural gas to be liquefied after sub-cooling by way of recovering cold vapor of the light refrigerant is additionally reduced to pressure (in 58 in Newton) which excludes formation of a two-phase flow as the expansion and then removal of vapor boil off in 158 provides for excluding two phase flow in 156 for example (see pump 156 in Newton). Krishnamurthy also discloses post subcooling expansion in 108 prior to excluding two phase flow by allowing boil off to be removed through 112.
Regarding claim 6, Newton discloses (Figure 1) a plant for liquefying natural gas, comprising a natural gas pre-cooling line (feed line 10 through 12/24/36), a natural gas sub-cooling circuit (line 34/47/48/54/58), a heavy refrigerant circuit (refrigerant circuit through 62), and a light refrigerant circuit (refrigerant circuit through 100/102); the natural gas pre-cooling line includes a sequence of at least one natural gas compressor (see rejection of claim 1, feed stream has purities removed and is compressed, the examiner also goes on official notice that compressors for feed streams are well known in the natural gas liquefaction art to provide proper feed pressures for liquefaction), at least one air cooler or water cooler (precooling can be provided in 12, however it is not explicitly providing water or air cooling however the examiner goes on official notice that pre-cooling a natural gas feed into a liquefaction plant with water or air coolers is well known in the art and can easily be utilized as a simple use of Known Technique to Improve Similar Devices, Methods, or Products in the Same Way in order to provide proper feed temperatures going into the heavy refrigerant cycle); and inter-tube spaces of heavy refrigerant vaporizers (12/24/36); the sub-cooling circuit includes a shell and tube heat exchanger 50 (see tubes 47/48/54 being cooled within the shells) and the first pressure reducer 116; the heavy refrigerant circuit includes a sequence of at least one heavy refrigerant compressor 62, at least one air cooler or water cooler 65/64 and inter-tube spaces of the heavy refrigerant vaporizers 12/24/36, outlets of which are connected to the heavy refrigerant compressor 62; the light refrigerant circuit includes a sequence of at least two light refrigerant compressors 100/102, at least one air cooler or water cooler located downstream from each light refrigerant compressor 104/106, as well as a double-flow light refrigerant superheater (see rejection and motivation with respect to claim 1 above, Krishnamurthy discloses an interchanger for heating/cooling light refrigerant upstream of a tube/shell heat exchanger subcooler), tube space of the heavy refrigerant vaporizer (within 86/88/89), first tube space of the shell and tube heat exchanger (114) and expander (116 replaced by turbine of Krishnamurthy, see rejection and motivation with respect to claim 1 above), wherein the natural gas sub-cooling line includes the second tube space of the shell and tube heat exchanger (47/48), an outlet of which is connected to the first heat exchange space of the light refrigerant vaporizer (54), an outlet of which is connected to the first pressure reducer (55 or 58); in the light refrigerant circuit, the last air cooler or water cooler (104/106 connected to interchanger 197 when modified by Krishnamurthy (rejection/motivation of claim 1 above), all of the circuit is technically connected to each other) is connected in sequence to the first heat exchange space of the double-flow superheater and the second tube space of the heavy refrigerant vaporizer (interchanger of Krishnamurthy added to Newton, and HE 86/88/89), a light refrigerant outlet of which is connected to two light refrigerant lines (outlet from 89 connected to 120/112), where the first line 112 includes the said expander (116 as modified, see claim 1) and the second line 120 includes a sequence of the first tube space of the shell and tube heat exchanger 122/124, the second pressure reducer 128, and the second heat exchange space of the light refrigerant vaporizer (from 56 within shell of 124), a gas outlet of which together with an outlet of the expander are connected to the inter-tube space of the shell and tube heat exchanger (outlet through 56 combines with outlet from turbine 116/52 and used in last space to cool 48/47/122/114 in shell), an outlet of which is connected to the second heat exchange space of the double-flow superheater (as modified by Krisnamurthy, see 197, 171 flowing through 197), an outlet of which is connected to the first light refrigerant compressor in a direction of flow 100/102.
Regarding claim 7, Newton discloses wherein the sub-cooling line contains a third pressure reducer, an inlet of which is connected to an outlet of the first tube space of the shell and tube heat exchanger, and an outlet of which is connected to an inlet of the first heat exchange space of the light refrigerant vaporizer (if this is referring to the sub-cooling line of natural gas, see expander 55 or 58 as the additional third expander).
Regarding claim 8, see the rejection of claim 3 above.
Conclusion
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/KEITH RAYMOND/Supervisory Patent Examiner, Art Unit 3798
