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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 6/2/2026 has been entered.
The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
Claims 1-11, 13-21 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the enablement requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim 1 recites “the liquefying agent being injected at the top of the first distillation column, above a biogas inlet, at a temperature T1 lower than or equal to the carbon dioxide desublimation temperature at the operating pressure of the first distillation column”.
A. The breadth of the claims:
The claims are drawn to a method of separating one or more compounds from a biogas.
B. The nature of the invention:
Distillation using a liquefying agent.
C. The state of the prior art:
The state of the art does not recognize how the temperature T1 can be lower than or equal to the carbon dioxide desublimation at the operating pressure of the first distillation column. The specification only describes pressure of the distillation column on the order of 20 or 21 bar (paragraph 40, 44). At those pressures, there is no desublimation temperature for carbon dioxide, as carbon dioxide does not have a desublimation pressure above ~5.17 bar.
D. The level of one ordinary skill in the art:
A designer or operator of cryogenic distillation systems.
E. The level of predictability in the art:
It is not predictable that carbon dioxide can have a desublimation temperature at 20 or 21 bar.
F. The amount of direction provided by the inventor:
The specification does not teach how carbon dioxide can have a desublimation temperature at 20 or 21 bar.
H. The quantity of experimentation needed to make or use the invention based on the content of the disclosure:
It does not appear that there is any amount of experimentation that would be useable to determine how to make or use the invention having desublimation temperature for carbon dioxide at 20 or 21 bar.
Based on the above analysis the claims are considered not enabled by the specification. While not explicit in the claims, the specification makes it clear that the pressure for the column are on the order of 20 and 21 bars (paragraphs 40 and 44). Carbon dioxide follows a well-known phase diagram where anytime the pressure is above 5.11 atm, carbon dioxide does not desublimates but melts. As such, it is clear that at the pressure of the column that is disclosed by the applicant, carbon dioxide does not have a desublimation temperature. The specific language that is not enabled is “at a temperature T1 lower than or equal to the carbon dioxide desublimation temperature at the operating pressure of the first distillation column”. While the specification and the claims later define T1 as being on the order of -100 C, this does not overcome the issues with enablement in claim 1 as those limitations are only further limiting a non-enabled limitation. As such, there is no working example provided and no direction by the inventor as to how the temperature T1 can be defined based on a desublimation temperature at a pressure where carbon dioxide does not desublimate and it does not appear that any quantity of experimentation would result in being able to make or use the invention based on the content of the disclosure
As such based on the analysis of the Wands factors, one of ordinary skill in the art could not make and use the claimed invention without exercising undue experimentation, therefore the claimed invention is not enabled.
Claims 2-11, 13-21 are rejected as being dependent upon a rejected claim.
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 1-11, 13-21 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 recites “the liquefying agent being injected at the top of the first distillation column, above a biogas inlet, at a temperature T1 lower than or equal to the carbon dioxide desublimation temperature at the operating pressure of the first distillation column” which is considered indefinite for the reasons provided above as to the lack of enablement as it is unclear how carbon dioxide can have a desublimation temperature as claimed. For the purpose of examination, this limitation is interpreted that temperature is at a temperature suitable for providing the liquefying agent for use as needed to liquefy components within the column.
The term “on the order of” in claim 3 is a relative term which renders the claim indefinite. The term “on the order of” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. For the purpose of examination, this limitation is understood that the stream has to be at a cryogenic temperature that would be used for methane reflux.
Claim 3 recites “the liquefying agent is injected into the first distillation column at a temperature T1 on the order of -100 C” which is considered indefinite. Claim 1 already has positively recited “a temperature T1 lower than or equal to the carbon dioxide desublimation temperature”.
The term “on the order of” in claim 15 is a relative term which renders the claim indefinite. The term “on the order of” is not defined by the claim, the specification does not provide a standard for ascertaining the requisite degree, and one of ordinary skill in the art would not be reasonably apprised of the scope of the invention. For the purpose of examination, this limitation is understood that the stream has to be at a cryogenic temperature that would be used for methane reflux.
Claim 15 recites “the liquefying agent is injected into the first distillation column at a temperature T1 on the order of -100 C” which is considered indefinite. Claim 1 already has positively recited “a temperature T1 lower than or equal to the carbon dioxide desublimation temperature”
Claims 2, 4-11, 13-14, 16-21 are rejected as being dependent upon a rejected claim.
Claim Interpretation
In claims 1 and 12, while the term “cryogenic distillation” is recited with respect to the second distillation column, this distillation is not considered to be at a cryogenic temperature as the separation of carbon dioxide as an overhead gas would not happen at cryogenic temperatures, which are considered to start well below -60 C, which is the coldest temperature recited in the specification. This limitation is understood to be distillation that allow for the separation as claimed into carbon dioxide and the liquefying agent.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 1-6, 9-11, 13-18, 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Holmes et al. (US Patent No. 4318723), hereinafter referred to as Holmes and further in view of Holmes et al. (US Patent no. 4462814), hereinafter referred to as Ryan and Gnanendran et al. (US PG Pub 20120186296), hereinafter referred to as Gnanendran and O’Brien (US Patent No. 4681612), hereinafter referred to as O’Brien and further in view of Mak et al. (US PG Pub 20080264100), hereinafter referred to as Mak.
With respect to claim 1, Holmes (Figure 1) a method for separating one or more compounds in the a liquid state or in a two-phase liquid/vapor state, containing methane and carbon dioxide (dry feed gas 10 includes methane and carbon dioxide, Column 6, lines 47-48 which is partially condensed in 16, Column 6, lines 55-56), wherein a first separation for separating the methane is carried out by cryogenic distillation in a first column (distillation column 18 distills the cryogenic cooled stream into overhead methane, Column 6, lines 55-63) comprising a column top brought to a temperature at which methane condensed at an operating pressure of the first distillation column (the temperature at the top of the column is -130 F at 600 psia, Column 8, lines 15-17 which is below where methane condenses, which means the top is at a condensation temperature of methane), the first separation being carried out by injecting into the first distillation column in a primary feed, liquefied at an equilibrium temperature making it possible to obtain a two-phase mixture ensuring the separation one or more compounds (partially liquefied feed gas is fed into the column and during that cooling is cooled to an equilibrium temperature at least initially, Column 5, lines 24-27, the column separates at least one component from methane),
in secondary feed, a liquefying agent in the liquid state compose of a hydrocarbon (recycled agent which is NGLs is recycled to the column via 66 or 70, Column 7, lines 12-37), the liquefying agent being injected at the top of the first distillation column, above a gas inlet (recycled agent is fed at the top of the column via 70, Column 7, line 36), at a temperature T1 lower than or equal to the carbon dioxide sublimation temperature at the operating pressure of the first distillation column (the additive is at -100 F before being added to the condenser for entering the column, so it would be either at that temperature when it enters the column at 70 or colder when it enters the column, which is a temperature suitable for providing the cooling necessary by the liquefying agent).
the liquefying agent being added in an amount proportional to the vapor flow rate of the carbon dioxide ascending to the top of the first distillation column (the amount of agent added to the column has a direct relationship with the amount of carbon dioxide in the feed stream, which means it would also have a direct relationship with the carbon dioxide vapor flowing up to the top in the column, Column 8, lines 34-45),
wherein a second separation of the compounds of the liquid mixture recovered at the end of the first separation and comprising carbon dioxide and the liquefying agent is carried out by cryogenic separation (bottoms liquid 28 forms stream 36 which contains the liquid mixture form the first separation and contains carbon dioxide and NGLS is separated in second separation equipment 38 to form a carbon dioxide stream 42 and a recycled agent stream 44, Column 7, lines 15-20) to reach a temperature and an equilibrium pressure allowing the separation of carbon dioxide and the liquefying agent in liquid residue (the recycled agent includes nonpolar liquids such as C3-C6 alkanes including NGLs, Column 7, lines 63-65, Column 8, lines 1-4).
Holmes does not teach the feed gas is a biogas such that the primary feed gas point is a biogas inlet.
Gnanendran teaches that various gas streams contain a mixture of methane, higher hydrocarbons and carbon dioxide including biogas (paragraph 52) which are separated to form a methane overhead and carbon dioxide bottoms stream (paragraphs 66 and 75).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Gnanendran to have the dry feed gas stream of Holmes have been a biogas stream containing methane, ethane, higher hydrocarbons (which as they are C3+ would include butane) and carbon dioxide since it has been shown that a simple substitution of one known element (feed gas origin for Holmes) for another (feed gas origin being biogas) to yield predictable results is obvious whereby as they are both known gas sources that require cryogenic distillation to separate the methane from carbon dioxide and both contain similar or the same general main components (CO2, CH4, C2+ hydrocarbons) one of ordinary skill in the art would have been able to carry out such a substitution with the reasonably predictable result of a stream that would be suitable for separation in the system of Holmes to produce a methane stream and a separate carbon dioxide stream.
Holmes as modified does not teach the second separation is in a second distillation column to teach allowing the separation of the carbon dioxide in the form of vapor at the top of the second distillation column and the liquefying agent at the bottom of the second distillation column.
Ryan (Figure 1) teaches that a second separation in a methane starts with a distillation column (34) to separate carbon dioxide from natural gas liquids including one that is eventually recycled back as the liquid agent to the original column such that the liquid from the first column (32) is separate into an overhead carbon dioxide vapor recovered as a gaseous CO2 product (42) with a carbon dioxide reflux and a bottoms liquid (44) which includes ethane and higher hydrocarbons which are later separated into the butane that is reeled as the liquefying agent (Column 4, line 60 – Column 5, line 25).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Ryan had the second separation of Holmes as modified include a distillation column to separate the carbon dioxide from the liquefying agent to form a gaseous overhead carbon dioxide recovered at least in part as a gaseous CO2 product with a carbon dioxide reflux and a bottom stream containing the liquid (recycled) agent since it has been shown that combining prior art elements to yield predictable results is obvious whereby it is common knowledge in the art that using distillation column as separation allows the recovery of high purity components of a distilled stream.
Holmes does not teach the cryogenic distillation is carried out at a temperature and equilibrium pressure.
O’Brien teaches that for purification in a low-temperature column the column is operated with pressure and temperature of the column selected to follow the equilibrium pressure and temperature for recovery of a purified carbon dioxide (Column 7, lines 25-29).
Therefore, it would have been obvious to a person having ordinary skill in the art at the time the invention was filed for the second distillation in the column of Holmes as modified based on the teaching of O’Brien to be carried out at an equilibrium pressure and temperature in order to provide a purified carbon dioxide from the column.
Holmes does not teach does not teach expansion of the liquid mixture as it is passed to the second distillation column.
Mak teaches that when a bottoms liquid stream (7) is passed from one column (58) to another (64) then that the stream is let down in pressure in a valve (63) between them (paragraph 34).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Mak provide an valve on the liquid bottom stream passing from the first distillation column of Holmes as modified to the second distillation column since it has been shown that combining prior art elements to yield predictable results is obvious whereby providing the valve and an expansion would provide what is common knowledge in the art of being able to reduce the pressure of the stream so that it was at a suitable pressure for a lower pressure distillation in the second stage of distillation.
With respect to claim 2, Holmes as modified teaches wherein the liquefying agent is injected into the first distillation column at a level at which the methane reflux is returned the first distillation column (the liquefying agent can be added via 23 as part of the stream from the condenser and thus is introduced along with the methane reflux at the same level).
With respect to claim 3, Holmes as modified does not teach wherein the liquefying agent is injected into the first distillation column at a temperature T1 on the order of -100°C.
Holmes teaches that the solids-preventing agents should be liquid at the overhead temperature in the distillation column and that the temperature of the overhead column depends upon the pressure of the column (Column 8, lines 8-20). Holmes further teaches different conditions including those at which the additive is added to the condenser including pressure for the column, temperatures for the column and temperature for the additives (Tables I, II, III) with different additive temperatures and different operating pressures and teaches which shows the relationship between solubility of the carbon dioxide and (Figures 6-9). As such, the temperature at which the liquefying agent is injected into the first distillation column is a result effective variable depending on the pressure of the column and the operating temperature of the column. Further, it appears that one of ordinary skill in the art at the time of the invention would have had a reasonable expectation of success in modifying Holmes as modified to have a temperature within the claimed range, as it only involves adjusting the dimension of a component disclose to require adjustment. Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to modify Holmes as modified to have had the liquefying agent injected into the first distillation column at a temperature T1 on the order or -100 C as a matter of routine optimization since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
With respect to claim 4, Holmes as modified teaches wherein the liquefying agent is subject to cooling in two stages under pressure before it is injected into the top of the first distillation column in order to reach temperature T1 (liquefying agent is cooled in both 40 and 22 and is at the pressure from the second separation, which is what brings it to T1).
With respect to claim 5, Holmes as modified teaches wherein the top of the first distillation column is cooled at least in part by the liquefying agent (the liquefying agent is added at the top of the column and thus provides cooling there).
With respect to claim 6, Holmes as modified teaches further comprising recovering the methane in a gas state at the end of the first separation (purified methane 20 leaving the top of the column would be vapor as it is up flowing out of the column and is being send to be condensed in 22).
With respect to claim 9, Holmes as modified teaches further comprising recovering the liquefying agent at the end of the second separation and redirecting at least sone of the recovered liquefying agent to the first distillation column (the second separation produces the recovered agent which is what is sent back to 18).
With respect to claim 10, Holmes as modified teaches wherein the liquefying agent is a linear or non-linear alkene hydrocarbon of the C3 to C7 family (the liquefying agent as shown in the Table 1, of the example is n-butane which is a linear alkene).
With respect to claim 13, Holmes as modified teaches wherein the biogas further comprises a hydrocarbon (the feed gas can comprise multiple hydrocarbons including butane, column 12-Column 13, line 10, which butane would include n-butane and i-butane) and wherein the liquid mixture recovered at the end of the first separation further comprises the hydrocarbon, and the liquid residue at the bottom of the second distillation column further comprise the hydrocarbon (both separations produce n-butane as a bottom product).
With respect to claim 11, Holmes as modified teaches wherein the liquefying agent comprises the same hydrocarbon present in the biogas (the mixture fed to the column can include nitrogen, ethane and other hydrocarbons include butane column 12-Column 13, line 10 and as the recycled agent is formed of C3-C7 alkenes, would include a hydrocarbon present in the biogas).
With respect to claim 14, Holmes as modified teaches wherein the liquefying agent exhibits the same physical-chemical properties exhibited by the hydrocarbon (they are both n-butane and would thus do the same thing).
With respect to claim 15, Holmes as modified does not teach wherein the liquefying agent is injected into the first distillation column at a temperature T1 on the order of -100°C.
Holmes teaches that the solids-preventing agents should be liquid at the overhead temperature in the distillation column and that the temperature of the overhead column depends upon the pressure of the column (Column 8, lines 8-20). Holmes further teaches different conditions including those at which the additive is added to the condenser including pressure for the column, temperatures for the column and temperature for the additives (Tables I, II, III) with different additive temperatures and different operating pressures and teaches which shows the relationship between solubility of the carbon dioxide and (Figures 6-9). As such, the temperature at which the liquefying agent is injected into the first distillation column is a result effective variable depending on the pressure of the column and the operating temperature of the column. Further, it appears that one of ordinary skill in the art at the time of the invention would have had a reasonable expectation of success in modifying Holmes as modified to have a temperature within the claimed range, as it only involves adjusting the dimension of a component disclose to require adjustment. Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to modify Holmes as modified to have had the liquefying agent injected into the first distillation column at a temperature T1 on the order or -100 C as a matter of routine optimization since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
With respect to claim 16, Holmes as modified teaches wherein the liquefying agent is subject to cooling in two stages under pressure before it is injected into the top of the first distillation column in order to reach temperature T1 (liquefying agent is cooled in both 40 and 22 and is at the pressure from the second separation).
With respect to claim 17, Holmes as modified teaches wherein the top of the first distillation column is cooled at least in part by the liquefying agent (the liquefying agent is added at the top of the column and thus provides cooling there).
With respect to claim 18, Holmes as modified teaches further comprising recovering the methane in a gas state at the end of the first separation (purified methane 20 leaving the top of the column would be vapor as it is up flowing out of the column and is being send to be condensed in 22).
With respect to claim 20, Holmes as modified teaches further comprising recovering the carbon dioxide in a gas state at the end of the second separation (the final carbon dioxide product as modified is a gas, which as it leaves the system can be considered recovered).
Claim(s) 7-8 and 19 is/are rejected under 35 U.S.C. 103 as being unpatentable over Holmes/Ryan/Gnanendran/O’Brien/Mak and further in view of Fieler et al. (US PG Pub 20080034789), hereinafter referred as Fieler.
With respect to claim 7, Holmes as modified teaches the second separation is carried out by cooling the top of the second distillation column to the condensation temperature of the carbon dioxide (carbon dioxide reflux is sent back to the column which would cool the column top to the same temperature which is a condensation temperature of carbon dioxide).
Holmes as modified does not teach the cooling is to between -50° Celsius and -60° Celsius as a function of the pressure reached after the expansion.
Fieler teaches that the amount of acid gas (which is impurities in Fieler) in the overhead of a column is controlled by multiple factors including operating temperature and operating pressure.
As such, the temperature operating temperature of the column (which would include the temperature of the overhead part of the column and thus the temperature the top of the column is cooled to) is a result effective variable which is set as one of multiple factors including operating pressure of the column (which would be related to the pressure after expansion) which is set to achieve a desired separation of components within the column. Further, it appears one of ordinary skill in the art would have had a reasonable expectation of success in modifying Holmes as modified as it involves only adjusting the dimension of a component (column temperature) known to require adjustment. Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have modified the operation of Holmes as modified to have had the cooling of the top of the second distillation column to between -50C and -60C as a function of the pressure reached after the expansion Therefore it would have been obvious to a person having ordinary skill in the art at the time the as a matter of routine optimization since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
With respect to claim 8, Holmes as modified teaches further comprising recovering the carbon dioxide in a gas state at the end of the second separation (the final carbon dioxide product as modified is a gas, which as it leaves the system can be considered recovered).
With respect to claim 19, Holmes as modified teaches the second separation is carried out by cooling the top of the second distillation column to the condensation temperature of the carbon dioxide (carbon dioxide reflux is sent back to the column which would cool the column top to the same temperature which is a condensation temperature of carbon dioxide).
Holmes as modified does not teach the cooling is to between -50° Celsius and -60° Celsius as a function of the pressure reached after the expansion.
Fieler teaches that the amount of acid gas (which is impurities in Fieler) in the overhead of a column is controlled by multiple factors including operating temperature and operating pressure.
As such, the temperature operating temperature of the column (which would include the temperature of the overhead part of the column and thus the temperature the top of the column is cooled to) is a result effective variable which is set as one of multiple factors including operating pressure of the column (which would be related to the pressure after expansion) which is set to achieve a desired separation of components within the column. Further, it appears one of ordinary skill in the art would have had a reasonable expectation of success in modifying Holmes as modified as it involves only adjusting the dimension of a component (column temperature) known to require adjustment. Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have modified the operation of Holmes as modified to have had the cooling of the top of the second distillation column to between -50C and -60C as a function of the pressure reached after the expansion Therefore it would have been obvious to a person having ordinary skill in the art at the time the as a matter of routine optimization since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
Claim(s) 12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Holmes and further in view of Gnanendran and Ryan.
With respect to claim 12, Holmes teaches an installation enabling the separation of at least sone of a gas in a liquid state or in a two-phase liquid/vapor state (Figure 5) containing methane and carbon dioxide (dry feed gas 10 includes methane and carbon dioxide, Column 6, lines 47-48 which is partially condensed in 16, Column 6, lines 55-56), the installation comprising:
a first distillation column configured to separate the methane from the carbon dioxide by cryogenic distillation column 18 distills the cryogenic cooled stream into overhead methane, Column 7, lines 55-63 and a bottom product that contains carbon dioxide, Column 8, lines 1-11) comprising a primary feed for the injection of the gas at an equilibrium temperature making it possible to obtain a two-phase mixture for ensuring the separation of the methane from the carbon dioxide (the feed is cooled in 16 to a cryogenic temperature to liquefy a portion of it before feeding it to column 18, Column 6, lines 54-56 with initial cooling to equilibrium, Column 5, lines 21-25) and a secondary feed for injection of a liquefying agent in the liquid state composed of a hydrocarbon or a mixture of hydrocarbon from the C3 to C7 family (recycled agent which is NGLs is recycled to the column via 66 or 70, Column 7, lines 12-37), the second feed being arranged to inject the liquefying agent at the top of the first distillation column above a gas inlet (recycled agent is fed at the top of the column via 70, Column 7, line 36),
a second separation for the separation of the carbon dioxide from a liquid mixture recovered at the end of the first separation comprising the carbon dioxide and the liquefying agent (bottoms liquid 28 forms stream 36 which contains the liquid mixture form the first separation and contains carbon dioxide and NGLS is separated in second separation equipment 38 to form a carbon dioxide stream 42 and a recycled agent stream 44, Column 7, lines 15-20).
Holmes does not teach the feed gas is a biogas such that the primary feed gas point is a biogas inlet.
Gnanendran teaches that various gas streams contain a mixture of methane, higher hydrocarbons and carbon dioxide including biogas (paragraph 52) which are separated to form a methane overhead and carbon dioxide bottoms stream (paragraphs 66 and 75).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Gnanendran to have the dry feed gas stream of Holmes have been a biogas stream containing methane, ethane, higher hydrocarbons (which as they are C3+ would include butane) and carbon dioxide since it has been shown that a simple substitution of one known element (feed gas origin for Holmes) for another (feed gas origin being biogas) to yield predictable results is obvious whereby as they are both known gas sources that require cryogenic distillation to separate the methane from carbon dioxide and both contain similar or the same general main components (CO2, CH4, C2+ hydrocarbons) one of ordinary skill in the art would have been able to carry out such a substitution with the reasonably predictable result of a stream that would be suitable for separation in the system of Holmes to produce a methane stream and a separate carbon dioxide stream.
Holmes as modified does not teach the second separation is a second distillation column.
Ryan (Figure 1) teaches that a second separation in a methane starts with a distillation column (34) to separate carbon dioxide from natural gas liquids including one that is eventually recycled back as the liquid agent to the original column such that the liquid from the first column (32) is separate into an overhead carbon dioxide vapor recovered as a gaseous CO2 product (42) and a bottoms liquid (44) which includes ethane and higher hydrocarbons which are later separated into the butane that is reeled as the liquefying agent (Column 4, line 60 – Column 5, line 25).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Ryan had the second separation of Holmes as modified include a distillation column to separate the carbon dioxide from the liquefying agent to form a gaseous overhead carbon dioxide and a bottom stream containing the liquid (recycled) agent since it has been shown that combining prior art elements to yield predictable results is obvious whereby it is common knowledge in the art that using distillation column as separation allows the recovery of high purity components of a distilled stream.
Claim(s) 21 is/are rejected under 35 U.S.C. 103 as being unpatentable over Holmes/Ryan/Gnanendran/O’Brien/Mak and further in view of Cuellar et al. (US PG Pub 20080282731), hereinafter referred to as Cuellar.
Holmes does not teach heating the biogas to a temperature of between -60 and -50 c before injecting the biogas into the first distillation column.
Cuellar teaches that to a distillation column can start as a liquid (Figure 1, LNG form tank 10 as stream 41, paragraph 12) and is heated (utility heat 14) to bring it to a two-phase state that is injected into the column (paragraph 12).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have had the feed stream of biogas of Holmes to have been a liquid stream and to have used a heater to bring it to the desired two-phase condition instead of the stream starting as a vapor stream that is cooled based on the teaching of Cuellar since it has been shown that a simple substitution of one known element for another to yield predictable result is obvious whereby as starting as a stream below the distillation temperature and heating it and starting as a stream above the distillation temperature and cooling it are both known ways of providing the desired feed stream it would have been prima facie obvious to have heated the stream to the required temperature for distillation so what would be common knowledge in the art that a stream that starts below the required temperature for the separation in the first distillation column can be properly prepared for distillation.
Holmes teaches that the temperature at which the feed gas is brought to can be a temperature sufficient to have it be partially liquid at a cryogenic temperature (Column 5, lines 54-55). As such, the specific temperature of the feed gas into the distillation column and thus the temperature of the gas that is heated in the modification would be a result effective variable. Further, it appears that one of ordinary skill in the art would have had a reasonable expectation of success in modifying the Holmes to have a temperature within the claimed range, as it involves only adjusting the dimension of a component disclosed to require adjustment. Therefore, it would have been obvious to one having ordinary skill in the art at the time of the invention to when heating the feed stream of Holmes as modified to temperature for distillation to have brought the temperature to between -60 and -50 C as a matter of routine optimization since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
Response to Arguments
Applicant's arguments filed 5/5/2026 have been fully considered but they are not persuasive.
Applicant page 8-9 that the temperature disclosed by Holmes is for additive added to the condenser which would not be the same temperature necessarily added to the column. This is not persuasive.
The claims require the temperature be "lower than or equal to the carbon dioxide desublimation pressure". The additive is at -100 F before being added to the condenser for entering the column, so it would be either at that temperature when it enters the column at 70 or colder when it enters the column which meets the limitation as best understood. Even applicants’ further argument about the additive being at -95 F to tray 1 would meet the limitation as claimed. As shown above, applicants’ column is operated at 20 bars as disclosed, and as such would not have a desublimation temperature. Thus, the limitation as claimed is best understood to be a below the triple point temperature, which the limitation as claimed meets.
The warmest desublimation temperature for carbon dioxide is -69 F, which would be well above -95 F. Applicant provides an example in the specification of the column pressure being at 20 bars, which. Further, as later shown in claim 3, the specific temperature as claimed, which is also indefinite, is obvious which applicant has provided no argument against, so it could also be shown to be obvious to have the limitation as claimed in claim 1 based on the analysis in claim 3.
Applicant argues page 8-9 that the general teaching of Holmes is not a recitation of "injection is proportional to the specific internal column flow". This is not persuasive. The claims do not require that there are any specific adjustments or control of the flow rate itself in regards to the proportionality, only that the injection is “proportional the vapor flow rate of the carbon dioxide ascending” and do not require anything beyond the casual relationship so as long as any relationship can be drawn between the two, the limitation is met by the prior art. The amount of carbon dioxide ascending in the column would be at least in part related to the composition of the feed, as the amount of carbon dioxide in the feed would have an effect on the amount of carbon dioxide ascending in the column and as such, as the amount of liquefying agent can be provided is related to the composition of the feed they can be said to be proportional. Additionally, as noted by applicant, Holmes also teaches the liquefying agent being related to the desired purity of the overhead methane, which is an additional teaching of the flow rate being proportional to the carbon dioxide vapor rising, as the methane content would be adjusted by removing rising carbon dioxide vapor with the liquefying agent.
Applicant's remaining arguments in regard to claim 1, page 10 are moot as they are addressed only to the alleged deficiencies which have been addressed in Holmes.
Applicant argues that adding agent to the condenser is not the same as injecting the liquefying agent into the first distillation column at the level at which the methane reflux is returned. This is not persuasive.
One having ordinary skill in the art would consider it obvious when reviewing Holmes that by adding the agent to the condenser it would mix with the stream that is the methane reflux stream and be returned to the column at the same level as part of the reflux stream.
Applicant’s argument in regard to claim 21 are moot as they do not apply to the rejection above, which provides additional prior art to show the obviousness of such a teaching.
Applicants arguments in regards to claims 7, 8 and 19 are moot as the rejection of claim 1 is maintained.
Applicant argues, page 13, that the combination of Holmes, Gnandendran and Ryan that the modification does not address the full claim language of having a liquefying agent at the top of the first distillation column injected above a biogas inlet. This is not persuasive.
Holmes already teaches injecting a liquefying agent at the top of the column above the primary feed gas point, the teaching lacking in Holmes is that the feed gas injected at that point is biogas, which Gnandendran renders obvious. Applicant is addressing each reference individually. The test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981). One of ordinary skill in the art would recognize that a feed gas formed of natural gas would contain similar components as that of biogas, including water and other components beyond just methane and carbon dioxide, and would dry the biogas as part of the operations. Further, Gnanendran while it discusses that water can be present in the stream, acknowledges that the gas stream of feed gas can be multiple different types of streams including natural gas and biogas (paragraph 52) and that the gas stream is dehydrated (paragraph 55) as part of processing, which as the feed gas of Holmes is a dry feed gas, one of ordinary skill in the art would recognize is also true when modifying Holmes. Holmes already has the feed gas inlet, below the inlet for the liquefying agent, such that when modified such that the feed gas is biogas, the biogas inlet would be below the liquefying agent as the change is in what the feed gas is, not where the feed gas inlet is located. Further, Gnanendran teaches a general separation system which can be used to separate different gases including and not limited to natural gas and biogas which would provide a suggestion to one of ordinary skill in the art that it would have been obvious to have used a different feed gas in Holmes. This reasoning does address the full claim language, as it can be shown that it would be obvious for the feed gas to have been from a different source, it would result in the limitations as claimed being obvious. The arguments made to Ryan are moot as they are only addressed to the alleged deficiencies above.
Conclusion
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/BRIAN M KING/Primary Examiner, Art Unit 3763
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