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 .
Priority
Receipt is acknowledged of certified copies of papers required by 37 CFR 1.55.
Information Disclosure Statement
The Information Disclosure Statement(s) submitted November 17, 2025 and January 27, 2026 is/are in compliance with the provisions of 37 CFR 1.97 and 1.98. Accordingly, the information disclosure statement(s) is/are being considered by the examiner.
The information disclosure statement filed July 25, 2025 fails to comply with 37 CFR 1.98(a)(2), which requires a legible copy of each cited foreign patent document; each non-patent literature publication or that portion which caused it to be listed; and all other information or that portion which caused it to be listed. A copy of the non-patent literature for the dissertation published in 2000 was not provided. In order to expedite prosecution, the IDS has been considered except for this reference.
Claim Objections
Claims 1 and 4 are objected to because of the following informalities:
Claim 1, line 7 recites “the centrifugal compressor operating point” which lacks proper antecedent basis. The word “the” should be changed to “a”.
Claim 4, line 2 recites “centrifugal compressor 5 is computed” and the number “5” should be deleted.
Appropriate correction is required.
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 1-15 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, line 11 introduces “a discharge outlet” however “a discharge outlet” was previously introduced in line 6. It is unclear if these are the same feature or different features. For the purpose of examination, they will be treated as the same feature.
Claim 1, line 12 also introduces “a discharge outlet” which raises the same issue. For the purpose of examination, line 12 will be treated as referring to the same feature.
Claims 2-15 depend from claim 1 and contain its limitations and therefore are rejected for the same reason.
Claim 2, lines 2-3 also introduce “a discharge outlet” which raises the same issue.
Claim 4 depends from claim 2 and contains its limitations, and therefore is rejected for the same reason.
Claim 3, line 2 recites “a distance of the CO2 compressor operating point from surge limit” which raises multiple issues. First, “a distance of the centrifugal compressor operating point from a surge limit” was previously introduced in claim 1, line 7. It is unclear if the “distance” of claim 3 is the same distance or a different “distance”. The claims use different language to refer to the operating point (“centrifugal compressor” vs “CO2 compressor”), which is either inconsistency or support for these being different features. Second, the word “the” should be added before “surge limit” in claim 3 to clarify that this is the same surge limit as claim 1.
Claim 4, line 1 recites “a discharge outlet,” however, claim 1 previously introduced “a discharge outlet” as stated above. For the purpose of examination, claim 4 will be treated as referring to the same discharge outlet.
Claim 4, line 4 recites “a CO2 mass flow at a suction inlet”, however claim 1 previously introduced both “a CO2 mass flow” and “a suction inlet” and it is unclear if these are the same feature or separate features. For the purpose of examination, claim 4 will be treated as referring to the same features.
Claim 9, line 2 recites “in particularly numerically solved”, and the phrase “in particularly” renders the claim unclear because it is unknown whether being numerically solved is required or merely a preference.
Any and all claims rejected above under 35 USC 112(b), if rejected with art below under sections 35 USC 102 and/or 103, is/are rejected as best understood.
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.
Claim(s) 1-4, 10, and 15 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 10,989,211 to Galeotti.
In Reference to Claim 1#
Examiner’s comment: the limitation “with CO2 in supercritical conditions” in the preamble is considered an intended use for the “method for performing anti-surge control”. If the body of a claim fully and intrinsically sets forth all of the limitations of the claimed invention, and the preamble merely states, for example, the purpose or intended use of the invention, rather than any distinct definition of the claimed invention’s limitations, then the preamble is not considered a limitation and is of no significance to claim construction (see MPEP §2111.02 II, first paragraph for further clarification). In this case, the method is applied to a gas flowing through a compressor system with anti-surge control.
Galeotti teaches:
A method for performing anti-surge control in a centrifugal compressor (50, 51, column 1, lines 7-10) working with a gas in conditions, the method comprising:
providing an anti-surge loop (line having valve 63 and line 61 looping back to line leading to compressor 51) including an anti-surge valve (63) configured to control CO2 flow in the anti-surge loop;
calculating a gas suction density at a suction inlet of the centrifugal compressor (can be calculated using equation 1 in column 5);
calculating a gas discharge density at a discharge outlet of the centrifugal compressor (can be calculated using equation 1 in column 5);
calculating a distance of the centrifugal compressor operating point from a surge limit (column 10, lines 3-9); and
regulating the anti-surge valve as a function of the distance of the centrifugal compressor operating point from the surge limit (column 9, lines 36-39).
Galeotti teaches using multiple parameters related through various equations, such as gas density, pressure, temperature, compressibility, mass flow, volume flow rate, and polytropic efficiency.
The suction density at the suction inlet of the compressor can be calculated using the pressure and temperature at the suction inlet, the molecular weight, and the gas constant using equation 1 on column 5, line 60.
The discharge density can be calculated using the same equation and the pressure and temperature at the discharge outlet.
The anti-surge valve is controlled based on an anti-surge algorithm, and the anti-surge algorithm is related to the operating point and its distance from the surge limit line (column 5, lines 15-17 and column 9, lines 35-38).
The operating point is determined using equation 16 in column 9, line 50 (column 10, lines 3-9). The equation uses pressures and temperatures at the suction side and discharge side. The pressures and temperatures are associated with their respective densities through equations 1 and 7 (column 5, line 60 and column 6, line 54, respectively).
The volumetric flow is calculated using the density, a pressure drop, and a constant using equation 3 (column 6, line 20). The mass flow is calculated using the volumetric flow and density as seen in equation 4 (column 6, line 29).
Galeotti does not explicitly and specifically state the anti-surge valve takes into account the calculated gas suction and discharge densities, and a gas volumetric flow at a discharge outlet of the centrifugal compressor or a parameter related to the gas volumetric flow at a discharge outlet of the centrifugal compressor, the gas volumetric flow at a discharge being related to a gas mass flow at a suction inlet.
The above equations are mathematical expressions of natural phenomena. As evidenced by the equations, the natural phenomena are all related. The various parameters can be expressed together when combining equations. Combining the equations can simplify an anti-surge algorithm by solving for a single parameter – in this case, the distance of the operating point from the surge limit line.
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Galeotti by regulating the anti-surge valve as a function of the distance of the operating point from the surge limit line taking into account the calculated suction and discharge densities, and volumetric flow at the discharge outlet for the purpose of simplifying the anti-surge algorithm.
In Reference to Claim 2#
Galeotti teaches:
The method of The method of wherein the CO2 volumetric flow is measured through a flow sensor (75) at a discharge outlet of the centrifugal compressor (column 5, lines 32-35).
In Reference to Claim 3#
Galeotti teaches:
The method of claim 1, wherein the anti-surge valve is opened/closed as a function of a distance of the gas compressor operating point from surge limit taking into account a ratio between:
the gas suction density, and
the gas discharge density.
As stated above, the suction and discharge densities are parameters which affect the distance of the gas compressor operating point from the surge limit line, which determines the position of the anti-surge valve – including opening and closing. Galeotti teaches a ratio of the suction density to the discharge density can be used when determining the gas pressure at the delivery side of the compressor (equation 7 on column 6, line 54).
For the same reasoning applied to claim 1, expressing the related parameters using a single equation simplifies the control of the system. It would have been obvious to further modify the method of Galeotti by opening/closing the anti-surge valve as a function of the distance of the gas compressor operating point from surge limit taking into account a ratio of the gas suction and discharge densities for the purpose of simplifying the anti-surge algorithm.
In Reference to Claim 4#
Galeotti teaches:
The method of claim 2, wherein a gas mass flow at a discharge outlet of the centrifugal compressor is computed starting from the gas volumetric flow at a discharge outlet of the centrifugal compressor using the gas suction density and the gas discharge density, and is equated to a gas mass flow at a suction inlet of the centrifugal compressor.
As stated above, Galeotti shows a relationship between the gas mass flow and gas volumetric flow (equations 3 and 4, column 6, lines 14-29). The suction density and discharge density is associated with the pressure at the suction and discharge sides respectively (equation 7). The gas mass flow at the suction inlet would equate to the gas mass flow at the discharge outlet through the conservation of mass.
For the same reasoning applied to claim 1, expressing the related parameters using a single equation simplifies the control of the system. It would have been obvious to further modify the method of Galeotti by computing the gas mass flow at the discharge outlet starting from the gas volumetric flow at the discharge outlet using the gas suction density and gas discharge density for the purpose of simplifying the anti-surge algorithm.
In Reference to Claim 10#
Examiner’s comment: the limitation “for a centrifugal compressor working with CO2 in supercritical conditions” in the preamble is considered an intended use for the “anti-surge control system”. If the body of a claim fully and intrinsically sets forth all of the limitations of the claimed invention, and the preamble merely states, for example, the purpose or intended use of the invention, rather than any distinct definition of the claimed invention’s limitations, then the preamble is not considered a limitation and is of no significance to claim construction (see MPEP §2111.02 II, first paragraph for further clarification). In this case, Galeotti teaches an anti-surge control system for a compressor.
Galeotti teaches:
An anti-surge control system (anti-surge controller 68 controlling anti-surge valve 64) for a centrifugal compressor (column 1, lines 7-10), the system being configured to carry out the method of claim 1 (see Figure 4).
In Reference to Claim 15#
Examiner’s comment: the limitation “working with CO2 in supercritical conditions” in the preamble is considered an intended use for the “compressor arrangement”. If the body of a claim fully and intrinsically sets forth all of the limitations of the claimed invention, and the preamble merely states, for example, the purpose or intended use of the invention, rather than any distinct definition of the claimed invention’s limitations, then the preamble is not considered a limitation and is of no significance to claim construction (see MPEP §2111.02 II, first paragraph for further clarification). In this case, Galeotti teaches a compressor arrangement which comprises an anti-surge control system.
Galeotti teaches:
A compressor arrangement comprising a centrifugal compressor (compressors 51, 52, column 1, lines 7-10), the arrangement comprising the anti-surge control system of claim 10 (see Figure 4).
Claim(s) 5-9 and 11-14 is/are rejected under 35 U.S.C. 103 as being unpatentable over US 10,989,211 to Galeotti as applied to claim 1 and 10 above, and further in view of “The GERG-2008 Wide-Range Equation of State of Natural Gases and Other Mixtures: An Expansion of GERG-2004” to Kunz et al (hereafter Kunz).
In Reference to Claim 5
Galeotti teaches:
The method of claim 1, wherein the gas suction density and the gas discharge density are calculated using both a second state equation (equation 1), wherein the second state equation is a real gas state equation.
Galeotti fails to teach:
The suction and discharge densities are calculated using a first state equation.
Kunz teaches:
A first state equation (GERG-2008 equation) which is capable of calculating a gas suction density and a gas discharge density (see Section 4.1 Numerical Description of GERG-2008). The equation can be used for carbon dioxide gas which is in supercritical conditions (see abstract).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Galeotti by also using a first state equation to calculate the gas suction density and gas discharge density as taught by Kunz for the purpose of being able to verify the calculations for the parameters using another equation.
In Reference to Claim 6
Galeotti as modified by Kunz teaches:
The method of claim 5, wherein the first state equation corresponds to GERG-2008 equation for CO2 in supercritical conditions (see abstract of Kunz).
In Reference to Claim 7
Galeotti as modified by Kunz teaches:
The method of claim 5, wherein the first equation is formulated as a compressibility being a function of at least temperature and density. The GERG-2008 equation is formulated as a compressibility being a function of at least a temperature and a density. The examiner notes paragraph 41 of the applicant’s specification also states the GERG-2008 equation has compressibility as a function of density and temperature.
In Reference to Claim 8
Galeotti as modified by Kunz teaches:
The method of claim 5, wherein the second equation is formulated as a compressibility being a function of at least temperature and pressure and density (see equation 1 of Galeotti).
In Reference to Claim 9
Galeotti as modified by Kunz teaches:
The method of claim 5, wherein the first equation and the second equation are equated and solved whereby a density is determined (see equation 1 of Galeotti and GERG-2008 equation).
In Reference to Claim 11
Galeotti as modified by Kunz teaches:
The anti-surge control system of claim 10, being configured to perform anti- surge control when the gas is at an inlet of the centrifugal compressor.
Galeotti fails to teach:
The gas is CO2 in supercritical conditions.
Kunz teaches:
A compressor system (“compressor stations”, see page 3032, Section 1, third paragraph) operates with CO2 in supercritical conditions (see abstract).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Galeotti by configuring the compressor to use CO2 in supercritical conditions as taught by Kunz for the purpose of having the method apply to the desired intended use (compressed CO2 gas).
In Reference to Claim 12
Galeotti as modified by Kunz teaches:
The anti-surge control system of claim 11, being configured to perform anti- surge control after an end of a start-up period of the centrifugal compressor when CO2 is in supercritical conditions at an inlet of the centrifugal compressor. The anti-surge control system of Galeotti is configured to perform while the compressor is operating, which includes after the end of the start-up period and when the CO2 is in supercritical conditions at the inlet.
In Reference to Claim 13
Galeotti as modified by Kunz teaches:
The anti-surge control system of claim 12, being configured to calculate CO2 suction density and CO2 discharge density before the end of the start-up period and after the end of the start-up period. Galeotti teaches the control system is capable of calculating the suction density and discharge density (using the equations cited above), which could be done at any time – including before the end of the start-up period and after the end of the start-up period.
In Reference to Claim 14
Galeotti as modified by Kunz teaches:
The anti-surge control system of claim 13, being configured to calculate CO2 suction density and CO2 discharge density using a second state equation (equation 1 of Galeotti) when the system performs anti-surge control.
Kunz further teaches a first state equation (GERG-2008 equation) which calculates the state of a gas (abstract).
It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the anti-surge control system of Galeotti as modified by Kunz by also using a first state equation to calculate the gas suction density and gas discharge density as taught by Kunz for the purpose of being able to verify the calculations for the parameters using another equation.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. US 3,292,846 to Harper teaches a compressor system which controls a recycle valve based on a density measurement.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to JASON GREGORY DAVIS whose telephone number is (571)270-3289. The examiner can normally be reached M-Th: 8:00-5:00, F: 8:00-12:00.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Nathan Wiehe can be reached at (571) 272-8648. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/JASON G DAVIS/Examiner, Art Unit 3745
/NATHANIEL E WIEHE/Supervisory Patent Examiner, Art Unit 3745
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