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 Objections
Claims 19-20, 22, 26-27, and 33-34 are objected to because of the following informalities:
In claim 19, line 7, “desorption step ii) and has lower content” should read “desorption step ii) and has a lower content”
In claim 20, lines 4-5, “contacting the resulting liquid portion” should read “contacting [[the]] a resulting liquid portion”
In claim 20, line 5, “the first recovered me-thane portion” should read “the first recovered [[me-thane]] methane portion”
In claim 20, line 8, “the intermediate re-covered gas” should read “the intermediate [[re-covered]] recovered gas”
In claim 20, line 9, “to the me-thane recovery unit” should read “to the [[me-thane]] methane recovery unit”
In claim 22, line 2, “the loaded first absorbent, or methane-lean loaded absorbent” should read “the loaded first absorbent, or the methane-lean loaded absorbent”
In claim 26, line 9, “the carbon dioxide rich intermediate” should read “the carbon dioxide-rich intermediate”
In claim 27, line 4, “a spent first strip gas and regenerated first” should read “a spent first strip gas and a regenerated first”
In claim 33, line 1, “from a combined biogas up-grading” should read “from a combined biogas [[up-grading]]upgrading”
In claim 33, line 3, “a carbon dioxide rich liquefaction feed” should read “a carbon dioxide-rich liquefaction feed”
In claim 33, line 12, “the carbon dioxide rich liquefaction feed” should read “the carbon dioxide-rich liquefaction feed”
In claim 34, line 3, “the carbon dioxide rich feed” should read “the carbon dioxide-rich feed”
In claim 34, line 7, “which desorption unit provides the carbon dioxide rich liquefaction feed” should read “[[which]] wherein the desorption unit provides the carbon dioxide-rich liquefaction feed”
Appropriate correction is required.
Claim Rejections - 35 USC § 112(b)
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 18-32 and 34 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 18 recites the limitation “wherein the first absorbent is a physical absorbent, preferably water” (emphasis added) in line 13. The term “preferably” renders the claim indefinite because it is unclear whether the limitations following the term are part of the claimed invention. Description of examples and preferences is properly set forth in the specification rather than in a single claim. See MPEP § 2173.05(c) and (d).
Claim 19 recites the limitation “wherein the methane-lean loaded first absorbent replaces the loaded first absorbent in the vacuum desorption step ii) and has a lower content of methane than the loaded first absorbent.” The claim limitation is a contradiction to the limitations of the claim upon which it depends and it is therefore unclear how the limitations of claim 18 (“in a vacuum desorption step, feeding the loaded first absorbent to a low-pressure desorption unit”) can precede the limitations of claim 19 (“wherein the methane-lean loaded first absorbent replaces the loaded first absorbent in the vacuum desorption step ii)”). The step of feeding the loaded first absorbent to a low-pressure desorption unit cannot be completed if the methane-lean loaded first absorbent replaces the loaded first absorbent prior to the vacuum desorption step and it is unclear in which order Applicant intends for the steps to occur.
Claim 20 recites the limitation “flashing the loaded first absorbent in a methane recovery unit and contacting the resulting liquid portion with an intermediate recovery gas in the methane recovery unit.” As claim 20 is dependent upon claim 19, it is unclear how the loaded first absorbent is to be flashed as claim 19 requires that, in the same methane recovery step, the loaded first absorbent is replaced by the methane-lean loaded first absorbent. Furthermore, claim 20 recites the limitation “obtaining, from the methane recovery unit, the first recovered methane portion and an intermediate methane-lean loaded first absorbent.” As the claim now indicates that the loaded first absorbent has been transformed into a first recovered methane portion and an intermediate methane-lean loaded first absorbent, it is unclear whether the limitation of claim 18 “in a vacuum desorption step, feeding the loaded first absorbent to a low-pressure desorption unit” is still a preceding step as the “loaded first absorbent” has now been transformed to a “recovered methane portion” and an “intermediate methane-lean loaded first absorbent.”
Claim 20 recites the limitations “contacting the resulting liquid portion with an intermediate recovered gas”, “flashing the intermediate methane-lean loaded first absorbent thereby providing the methane-lean first absorbent and the intermediate recovered gas”, and “pressurizing and feeding the intermediate recovered gas to the methane recovery unit.” The “intermediate recovered gas” is obtained from a step that is preceded by a step in which the “intermediate recovered gas” is used and it is therefore unclear how the subsequent steps may be performed.
Claim 21 recites the limitation “the gas” in line 3. There is insufficient antecedent basis for this limitation in the claim.
Claim 21 recites the limitation “contacting the gas of the methane recovery unit with an intermediate absorbent providing the first recovered methane portion.” Claim 21 is dependent upon claim 19 which recites the limitation “recovering methane from the loaded first absorbent prior to the vacuum desorption step ii), optionally by flashing the loaded first absorbent, providing a first recovered methane portion and a methane-lean loaded first absorbent.” (emphasis added) It is unclear whether claim 21 requires or replaces the optional flashing in order to produce a first recovered methane portion.
Claim 23 recites the limitation “wherein the strip gas of step ii) is obtained by flashing the loaded first absorbent.” Claim 23 is dependent upon claim 22, which recites the limitation of “contacting the loaded first absorbent, or methane-lean loaded absorbent if present, with a strip gas.” The strip gas is obtained by flashing the loaded first absorbent, but the loaded first absorbent is contacted with the strip gas as required by claim 22 to produce other products (the carbon dioxide-rich intermediate and the lean first absorbent), so it is unclear how the limitations of claim 23 are to be incorporated into the limitations of claim 22, such that the source and destination of the strip gas are consistent. Note that the strip gas is obtained from a flashing step of the loaded first absorbent upstream of step ii, so the loaded first absorbent is transformed prior to step ii because a gas is obtained from it, which appears to be inconsistent with step ii.
Regarding claim 24, the phrase "such as" renders the claim indefinite because it is unclear whether the limitations following the phrase are part of the claimed invention. See MPEP § 2173.05(d).
Claim 27 recites the limitations “the intermediate absorbent” and “the third absorbent” in line 7. There is insufficient antecedent basis for these limitations in the claim.
Claim 28 recites the limitation “the first recovered methane portion” in line 2. There is insufficient antecedent basis for this limitation in the claim.
Claim 29 recites the limitations “the intermediate absorbent” and “the third absorbent” in line 16. There is insufficient antecedent basis for these limitations in the claim.
Claim 31 recites the limitation “the carbon dioxide intermediate” in lines 2-3. There is insufficient antecedent basis for this limitation in the claim.
Claims 22, 25-26, 30, and 32 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, due to their dependency from claim 18.
Claim 34 recites the limitation “contacting the loaded physical absorbent with the carbon dioxide-rich feed in a pre-liquefaction stripper, prior to the liquefaction process in step b), thereby providing the physical absorbent and an enriched liquefaction feed for step b).” As claim 34 is dependent upon claim 33, it is unclear how the limitation of claim 33 “liquifying the carbon dioxide-rich feed in the liquefaction process” can still be met if said carbon dioxide-rich feed is first contacted with the loaded physical absorbent. Contacting the carbon dioxide-rich feed with the loaded physical absorbent will change the composition of said carbon dioxide-rich feed and the limitation of step b) in claim 33 can no longer be met.
Claim Rejections - 35 USC § 112(d)
The following is a quotation of 35 U.S.C. 112(d):
(d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
The following is a quotation of pre-AIA 35 U.S.C. 112, fourth paragraph:
Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA 35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.
Claim 19 is rejected under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends. Applicant may cancel the claim, amend the claim to place the claim in proper dependent form, rewrite the claim in independent form, or present a sufficient showing that the dependent claim complies with the statutory requirements.
Claim 19 recites the limitation “wherein the methane-lean loaded first absorbent replaces the loaded first absorbent in the vacuum desorption step ii) and has a lower content of methane than the loaded first absorbent.” A step of replacing the loaded first absorbent with a methane-lean loaded first absorbent, which has a different composition than the loaded first absorbent, indicates that the claim is not incorporating all the limitations of the claim from which it depends.
Claim Rejections - 35 USC § 102
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claim 18 is rejected under 35 U.S.C. 102(a)(1) as being anticipated by European Patent Publication No. EP 3421114 A2 to Lebbe (hereinafter referred to as Lebbe).
Regarding claim 18, Lebbe teaches a method for treating a biogas feed comprising methane and carbon dioxide to provide an upgraded biogas and a purified carbon dioxide product (¶0001),
which method comprises the steps of: i) in a first absorption step, contacting the biogas feed with a first absorbent in a first absorber (Fig. 1, cylindrical tank 110 receives biogas through orifice 115 ; ¶0026 “Consequently, on contact with water, the carbon dioxide contained in the biogas dissolves in the water.”) thereby providing an enriched biogas and a loaded first absorbent, the loaded first absorbent having a higher content of carbon dioxide than the first absorbent (¶0026 “on contact with water, the carbon dioxide contained in the biogas dissolves in the water. The methane resulting from the biogas continues to rise and is discharged via an outlet 168” ; prior to contact with the biogas the water will have a lower carbon dioxide concentration than after contact),
ii) in a vacuum desorption step, feeding the loaded first absorbent to a low-pressure desorption unit with an operating pressure which is lower than ambient pressure (Fig. 1, tank 250 receives CO2-loaded water through discharge channel 116 ; ¶0040 “The device 200, dedicated to degassing the water and to extracting the CO2, comprises a second separation column 220 in the form of a cylindrical tank 250 surmounted by a preferably cylindrical separation pipe 260. This second column is advantageously placed under vacuum at a pressure that can range for example up to 1 bar below atmospheric pressure, preferably less than -0.5 bar”) providing a carbon dioxide-rich intermediate (¶0042 “The CO2 which escapes is driven by a vacuum pump towards recovery means”) and a lean first absorbent (¶0050 “The degassed water thus evacuated is then directed toward the container 300 in order to be pumped again by the first water pump P1 to supply the device 100 for washing and separating constituents of a biogas.”), and optionally,
iii) in a liquefaction step, liquefying the carbon dioxide-rich intermediate in a liquefaction process thereby providing the purified carbon dioxide product and a non-condensed portion (¶0057 “The system according to the invention may also comprise a liquefaction unit capable of liquefying the recovered CO2.” ; Any other gas present in the liquefaction unit which does not condense in the refrigeration cycle will be considered a “non-condensed portion”),
wherein the first absorbent is a physical absorbent, preferably water (¶0005 “Water is preferred as an aqueous solution for dissolving CO2”), and further wherein the first absorbent is obtained from the lean first absorbent ((¶0050 “The degassed water thus evacuated is then directed toward the container 300 in order to be pumped again by the first water pump P1 to supply the device 100 for washing and separating constituents of a biogas.”).
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:
Determining the scope and contents of the prior art.
Ascertaining the differences between the prior art and the claims at issue.
Resolving the level of ordinary skill in the pertinent art.
Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 18-19, 22, and 24 are rejected under 35 U.S.C. 103 as being unpatentable over U.S. Patent Publication No. US 2023/0271128 A1 to Find (hereinafter referred to as Find), and further in view of Lebbe.
Regarding claim 18, Find teaches a method for treating a biogas feed comprising methane and carbon dioxide (¶0002 “The present invention relates to the upgrading of biogas … where the main components of the biogas are methane and carbon dioxide”) to provide an upgraded biogas and a purified carbon dioxide product (¶0033 “Carbon dioxide at a high purity can be a secondary product from a biogas upgrade process”),
which method comprises the steps of: i) in a first absorption step, contacting the biogas feed with a first absorbent in a first absorber thereby providing an enriched biogas and a loaded first absorbent (Fig. 2, biogas G1 enters first absorber A2 to form first gas effluent G3 (upgraded biogas) and first liquid effluent L1 (loaded first absorbent); ¶0016 “recovering or further processing the first gas effluent as an upgraded biogas stream.”), the loaded first absorbent having a higher content of carbon dioxide than the first absorbent (¶0106 “thereby generating a first liquid effluent L1 which has an increased content of carbon dioxide compared to the first absorbing agent L4”),
ii) in a desorption step, feeding the loaded first absorbent to a low-pressure desorption unit providing a carbon dioxide-rich intermediate and a lean first absorbent (Fig. 2, first liquid effluent L1 becomes flash liquid effluent L2 before being depressurized by valve V2 and entering stripper unit A4 wherein it is separated into regenerated absorbing agent L3 and stripper gas effluent G5 ; ¶0030 “stripping the flash liquid effluent with the stripper gas feed thereby obtaining a stripper gas effluent having a higher content of carbon dioxide than the stripper gas feed and a regenerated physical absorbing agent.” ; ¶0109 “flash liquid effluent L2 is led to the top of stripper unit A4, through valve V2 wherein the pressure is reduced.”), wherein the first absorbent is a physical absorbent, preferably water (¶0050 “Suitably, the first and second physical absorbing agent are selected from water,”), and further wherein the first absorbent is obtained from the lean first absorbent (Fig. 2, regenerated absorbing agent L3 becomes first absorbing agent L4 ; ¶0031 “By stripping the dissolved gasses from the second flash effluent, the physical absorbing agent is regenerated and may be re-used.”).
As step iii) of the instant claim is “optional”, it is not necessary for Find to teach the limitations of in a liquefaction step, liquefying the carbon dioxide-rich intermediate in a liquefaction process thereby providing the purified carbon dioxide product and a non-condensed portion.
However, Find does not teach wherein the desorption step is a vacuum desorption step, wherein the loaded first absorbent is fed to a low-pressure desorption unit with an operating pressure which is lower than ambient pressure.
However, Lebbe teaches a method for treating a biogas feed comprising methane and carbon dioxide to provide an upgraded biogas and a purified carbon dioxide product (¶0001 “The invention relates to a system for separating and purifying two component gases of a gas mixture. A particularly advantageous application of such a system relates to the separation and purification of methane and carbon dioxide contained in a biogas.”), wherein the method comprises a vacuum desorption step, feeding a loaded first absorbent to a low-pressure desorption unit with an operating pressure which is lower than ambient pressure (Fig. 1, tank 250 receives CO2-loaded water through discharge channel 116 ; ¶0040 “The device 200, dedicated to degassing the water and to extracting the CO2, comprises a second separation column 220 in the form of a cylindrical tank 250 surmounted by a preferably cylindrical separation pipe 260. This second column is advantageously placed under vacuum at a pressure that can range for example up to 1 bar below atmospheric pressure, preferably less than -0.5 bar”). Lebbe further teaches wherein the use of a vacuum desorption step also aids in the recovery of the separated carbon dioxide (¶0047 “These bubbles, when they pass through the channel 252, can then degas in the tank 210 and be driven, by virtue of the vacuum created, toward a recovery means.”).
Find and Lebbe are considered analogous to the claimed invention because they are in the same field of methane and carbon dioxide separation of a biogas feed stream. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the method as taught by Find could be modified to incorporate a vacuum in the desorption step to allow for separation of carbon dioxide from the water absorbent and allow for easier recovery of the released carbon dioxide. Furthermore, a simple substitution of one known element for another to obtain predictable results (the desorption of carbon dioxide from the water absorbent) supports a prima facie case of obviousness. See MPEP § 2143(I)(B).
Regarding claim 19, Find and Lebbe teach the method as applied to claim 18 above. Find further teaches wherein the method comprises a step of: in a first methane recovery step, recovering methane from the loaded first absorbent prior to the vacuum desorption step ii) (Fig. 2, flash liquid effluent L2’ is sent to flash unit A3 to form flash gas effluent G4 ; ¶0013 “flashing the depressurized second liquid effluent thereby obtaining a flash gas effluent comprising methane”), optionally by flashing the loaded first absorbent (Fig. 2, flash unit A3), providing a first recovered methane portion and a methane-lean loaded first absorbent (Fig. 2, flash unit A3 produces flash gas effluent G4 (recovered methane) and flash liquid effluent L2 (methane-lean loaded first absorbent) ; ¶0013 “thereby obtaining a flash gas effluent comprising methane and a flash liquid effluent having a lower content of methane”), wherein the methane-lean loaded first absorbent replaces the loaded first absorbent in the vacuum desorption step ii) and has a lower content of methane than the loaded first absorbent (Fig. 2, flash liquid effluent L2 is transported to stripper unit A4 ; ¶0013 “thereby obtaining a flash gas effluent comprising methane a flash liquid effluent having a lower content of methane than the second liquid effluent” ; ¶0011 “thereby obtaining a second liquid effluent having a lower content of methane than the first liquid effluent.” ; if the flash liquid effluent has a lower methane content than the second liquid effluent, which has a lower methane content than the first liquid effluent, Find reads on the limitation of wherein the methane-lean loaded first absorbent has a lower methane content than that of the loaded first absorbent).
Regarding claim 22, Find and Lebbe teach the method as applied to claim 18 above. Find further teaches wherein the vacuum desorption step ii) comprises contacting the loaded first absorbent, or methane-lean loaded absorbent if present, with a strip gas in the low-pressure desorption unit providing the carbon dioxide-rich intermediate and the lean first absorbent (¶0029-0030 “feeding the flash liquid effluent and a stripper gas feed into a stripper unit, and stripping the flash liquid effluent with the stripper gas feed thereby obtaining a stripper gas effluent having a higher content of carbon dioxide than the stripper gas feed and a regenerating physical absorbing agent.”), the carbon dioxide-rich intermediate having a higher content of carbon dioxide than the strip gas (¶0030 “obtaining a stripper gas effluent having a higher content of carbon dioxide than the stripper gas feed”).
Regarding claim 24, Find and Lebbe teach the method as applied to claim 22 above. Find further teaches wherein the strip gas of step ii) is a gas which allows carbon dioxide to be stripped in the low-pressure desorption unit, such as air, nitrogen, or methane (¶0032 “The stripper gas feed may suitably be air, but other gases can be considered such as e.g. nitrogen or oxygen.”).
Claim 23 is rejected under 35 U.S.C. 103 as being unpatentable over Find and Lebbe, and further in view of Canadian Patent Publication No. CA 3135894 A1 to Schmidt et al. (hereinafter referred to as Schmidt).
Regarding claim 23, Find and Lebbe teach the method as applied to claim 22 above. Find and Lebbe do not teach wherein the strip gas of step ii) is obtained by flashing the loaded first absorbent, or the methane-lean loaded first absorbent if present, upstream of the low-pressure desorption unit.
However, Schmidt teaches a method for the removal of carbon dioxide from a gas stream (Abstract “The present invention relates to a process for producing hydrogen and for separating carbon dioxide from synthesis gas using a physical absorption medium.”) that has an absorption step and a desorption step (Pg. 6, lines 5-6 “removing carbon dioxide from the cooled synthesis gas via the cool absorption medium in a physical absorption step” ; Pg. 14, lines 25-28 “In particular the laden absorption medium in the flash stage arranged downstream of the at least first flash stage is heated by the abovementioned compression heat to facilitate desorption of the carbon dioxide in the downstream flash stage.”) wherein during the desorption step a strip gas is used to separate carbon dioxide from the loaded absorbent (Pg. 12, lines 20-23 “One embodiment of the process according to the invention is characterized that absorption medium vapours obtained in the distillation step are utilized as a stripping medium for removal of carbon dioxide in the downstream flash stage according to step (e).”), wherein said stripping gas is obtained by flashing the loaded first absorbent upstream of a desorption unit (Pg. 12, lines 24-29 and Pg. 13, lines 1-3 “The distillation step for separation of water from the absorption medium arranged downstream of step (e) generates absorption medium vapours … Instead of condensing these absorption medium vapours and recycling them to step (d) as liquid absorption medium, said vapours are in this embodiment utilized as stripping medium for removal of the carbon dioxide in the downstream flash stage according to step (e). This makes it possible to further increase the amount of separated carbon dioxide without any additional energy requirements.”). Schmidt further teaches that the use of the recovered gases as a strip gas in a downstream step allows for easier processing as they all consist of the same materials (Pg. 13, lines 8-11 “It is a further advantage that the absorption medium vapours obtained in the distillation step are chemically identical to the absorption medium. Accordingly, no “foreign” stripping medium requiring subsequent removal form the stripped gas is introduced into the absorption medium.”).
Find, Lebbe, and Schmidt are considered analogous to the claimed invention because they are in the same field of carbon dioxide recovery from mixed gas streams. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method as taught by Find and Lebbe to include an additional flashing step upstream of the desorption unit to produce the strip gas for the desorption step as taught by Schmidt to increase the overall carbon dioxide recovery and allows for efficient stripping without introducing an additional component that may need to be removed in a later method step.
Claim 25 is rejected under 35 U.S.C. 103 as being unpatentable over Find and Lebbe, and further in view of International Patent Publication No. WO 2017/114882 A1 to Find (hereinafter referred to as Find2).
Regarding claim 25, Find and Lebbe teach the method as applied to claim 18 above. Lebbe further teaches liquefaction step iii). Find and Lebbe do not explicitly teach recycling the non-condensed portion to the first absorber. However, Find teaches that gas streams can be recycled to the first absorber throughout the method to optimize methane recovery (¶0047 “The method according to the invention provides a means for efficiently recycling the methane from the loaded physical absorbing agent which reduces the amount of carbon dioxide which is recycled alongside the methane without losing methane.” ; ¶0107 “The recycle of the spent regeneration stream G3’’’ is done so as to not lose the methane contained therein.”).
Find2 teaches a method for recovering carbon dioxide and methane from a biogas (Pg. 3, lines 7-11 “The present invention relates to a method for storing energy by combing a process for recovering carbon dioxide from a gas stream, such as a biogas … to provide carbon dioxide which is reacted to provide preferably methane”) wherein the liquefaction of carbon dioxide occurs (Fig. 1, liquefaction of CO2 occurs after purification of CO2) and wherein the non-condensed portion of the liquefaction step is recycled to a first absorber to optimize the methane recovery (Pg. 12, lines 7-8 “to provide a liquid carbon dioxide stream and a purge gas stream containing CO2 and non-condensable gases” ; Pg. 12, lines 13-15 “To improve the methane recovery from the purge gas stream, the stream may be returned to absorber A1.”).
Find, Lebbe, and Find2 are considered analogous to the claimed invention because they are in the same field of biogas separation and purification. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method as taught by Find and Lebbe to incorporate the non-condensed portion recycling step as taught by Find2 to further recover methane.
Claim 32 is rejected under 35 U.S.C. 103 as being unpatentable over Find and Lebbe, and further in view of European Patent Publication No. EP 0180670 A1 to Jury et al. (hereinafter referred to as Jury).
Regarding claim 32, Find and Lebbe teach the method as applied to claim 18 above. Find and Lebbe do not teach wherein the method further comprises a pre-wash step prior to the first absorption step.
However, Jury teaches the removal of carbon dioxide from a biogas stream (Abstract “Biogas … is scrubbed to remove the CO2 by two spray scrubbers”) through a series of absorption steps (Fig. 2, first stage spray scrubber 8 and second stage spray scrubber 14) wherein, prior to the first absorption step, a pre-wash step of the biogas feed (Pg. 11, lines 21-23 “It is also preferred for a pre-wash (desirably regenerative) to be provided upstream of the scrubbers and the mixing chamber (if any) to wash solids out of the gas stream.”): in the pre-wash step, contacting the biogas feed with a pre-wash liquid in a pre-wash unit, thereby providing a spent pre-wash liquid and a washed biogas feed (Fig. 2, prewash device 3 ; Pg. 16, lines 17-19 “Before passing into the extractor the gas passes through a prewash device 3 to remove solids, e.g. organic detritus.”), wherein the spent pre-wash liquid is discarded or regenerated by heat treatment (Pg. 16, lines 22-25 “The dirty water at the bottom of tower 3 is cleaned by centrifugation and passed to an immersion heater to be heated before being re-sprayed.”), the pre-wash liquid is a physical absorbent (Pg. 16, lines 19-20 “The prewash is preferably a hot water wash”), and the washed biogas feed is sent to the first absorber (Fig. 2, washed biogas is compressed before entering first stage spray scrubber 8).
Find, Lebbe, and Jury are considered analogous to the claimed invention because they are in the same field of biogas purification and recovery. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method as taught by Find and Lebbe to incorporate the pre-wash step as taught by Jury to ensure any solids are removed from the gas stream prior to the absorption step.
Allowable Subject Matter
Claim 33 is allowed.
The following is a statement of reasons for the indication of allowable subject matter:
Claim 33 requires:
A method for recovering carbon dioxide from a combined biogas upgrading process and a carbon dioxide liquefaction process, which method comprises the steps of
a) obtaining a carbon dioxide-rich liquefaction feed from the biogas upgrading process, which biogas upgrading process removing carbon dioxide from a biogas feed,
b) liquifying the carbon dioxide-rich feed in the liquefaction process thereby providing a purified carbon dioxide product and a non-condensed portion,
c) contacting the non-condensed portion obtained in step b) with a physical absorbent in a post-liquefaction absorber thereby providing a washed non-condensed portion and a loaded physical absorbent, the washed non-condensed portion having a lower content of carbon dioxide than the non-condensed portion,
d) regenerating the loaded physical absorbent to release carbon dioxide therefrom and recycling the released carbon dioxide into the carbon dioxide-rich liquefaction feed obtained from the biogas upgrading process.
The underlined portion of claim 33 indicates the limitations which the Examiner has found to be non-obvious in view of the prior art. The combination of Find and Lebbe are the nearest prior art.
Neither Find and Lebbe nor the related prior art teach the method steps of contacting the non-condensed portion obtained in step b) with a physical absorbent in a post-liquefaction absorber thereby providing a washed non-condensed portion and a loaded physical absorbent, the washed non-condensed portion having a lower content of carbon dioxide than the non-condensed portion, and regenerating the loaded physical absorbent to release carbon dioxide therefrom and recycling the released carbon dioxide into the carbon dioxide-rich liquefaction feed obtained from the biogas upgrading process.
Furthermore, neither Find and Lebbe nor the related prior art provide a rationale for modifying any of the previously discussed teachings to meet all of the requirements as set forth by claim 33; Find and Lebbe make no mention regarding further processing of a non-condensed portion from the liquefaction process nor do they mention recycling the captured carbon dioxide and such a modification would therefore not have been obvious.
Claims 20-21, 26-31, and 34 would be allowable if rewritten to overcome the rejection(s) under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), 2nd paragraph, set forth in this Office action and to include all of the limitations of the base claim and any intervening claims.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to RACHEL MARIE SLAUGOVSKY whose telephone number is (571)272-0188. The examiner can normally be reached Monday - Friday 8:30 am - 5:30 pm EST.
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/RACHEL MARIE SLAUGOVSKY/Examiner, Art Unit 1776
/Jennifer Dieterle/Supervisory Patent Examiner, Art Unit 1776
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