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 .
Response to Amendment
The amendment filed January 27th, 2026 has been entered. Claims 27-36 and 38-47 remain pending in the application.
Response to Arguments
Applicant’s arguments, see Applicant Arguments/Remarks, filed January 27th, 2026, with respect to the rejection of claim 27 under 35 U.S.C. 103 have been fully considered and are persuasive. Therefore, the rejection has been withdrawn. However, upon further consideration, a new ground of rejection is made in view of U.S. Patent No. 9988326 to Paget et al. (hereinafter referred to as Paget), and further in view of admitted prior art from the Applicant’s specification (¶044), Evonik Industries SEPURAN®Green membrane.
It should be noted that Applicant argues Paget does not disclose the claimed venting pattern of claim 27. The Examiner respectfully disagrees.
Paget teaches that the third and fourth permeates are either vented to the atmosphere or treated in a thermal oxidizer (Col. 7, lines 10-12 “The third permeate 12 is in the form of a gas stream; it is discharged from the process in order to be used or released.” ; Claim 5 “The process of claim 1, wherein the third and fourth permeates are either vented to atmosphere or treated in a thermal oxidizer.”). Applicant asserts that Paget teaches that the third and fourth permeate are either vented together or treated together. However, a recitation of the intended use of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. If the prior art structure is capable of performing the intended use, then it meets the claim. Paget does not exclude the possibility of discharging the third permeate while sending the fourth permeate to a methane oxidation unit and is therefore capable of performing such a function. Furthermore, Paget explicitly teaches that the venting of the third and fourth permeates need not be used in the same manner as one another (Col. 4, lines 43-46 “The third and fourth permeates are discharged from the process; they may – independently or together – be for example treated by thermal oxidation, used for upgrading CO2, or simply released to the atmosphere.” ; italics added for emphasis).
Applicant additionally asserts that “There is no indication that the thermal oxidizer is part of the facility, that the facility includes a conduit for delivering permeate to a thermal oxidizer or that thermal oxidation takes place immediately after venting.” See Applicant Arguments/Remarks, pg. 13. The Examiner respectfully disagrees.
Firstly, it is noted that the features upon which applicant relies (i.e., thermal oxidation taking place immediately after venting) are not recited in the rejected claim. Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims. See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993). As to the argument that Paget gives no indication that the thermal oxidizer is part of the facility, Paget explicitly teaches a thermal oxidizer as part of the facility (Claim 11 of Paget “The facility of claim 8, further comprising a thermal oxidizer configured to receive the third and fourth permeates.”). Finally, although Paget does not explicitly teach a conduit for delivering the permeate to the thermal oxidizer, Paget teaches that the thermal oxidizer is configured to receive the third and fourth permeates – it would be obvious to one of ordinary skill in the art that in order for the transfer of the permeate from the membrane to the thermal oxidizer to occur, there must be a mechanism in which the permeate can travel (i.e., a conduit or pipe). For these reasons, Paget is still relied upon in the rejection of claim 27 under 35 U.S.C. 103 as discussed below.
Claim Interpretation
The following is a quotation of 35 U.S.C. 112(f):
(f) Element in Claim for a Combination. – An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.
The following is a quotation of pre-AIA 35 U.S.C. 112, sixth paragraph:
An element in a claim for a combination may be expressed as a means or step for performing a specified function without the recital of structure, material, or acts in support thereof, and such claim shall be construed to cover the corresponding structure, material, or acts described in the specification and equivalents thereof.
The claims in this application are given their broadest reasonable interpretation using the plain meaning of the claim language in light of the specification as it would be understood by one of ordinary skill in the art. The broadest reasonable interpretation of a claim element (also commonly referred to as a claim limitation) is limited by the description in the specification when 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, is invoked.
As explained in MPEP § 2181, subsection I, claim limitations that meet the following three-prong test will be interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph:
(A) the claim limitation uses the term “means” or “step” or a term used as a substitute for “means” that is a generic placeholder (also called a nonce term or a non-structural term having no specific structural meaning) for performing the claimed function;
(B) the term “means” or “step” or the generic placeholder is modified by functional language, typically, but not always linked by the transition word “for” (e.g., “means for”) or another linking word or phrase, such as “configured to” or “so that”; and
(C) the term “means” or “step” or the generic placeholder is not modified by sufficient structure, material, or acts for performing the claimed function.
Use of the word “means” (or “step”) in a claim with functional language creates a rebuttable presumption that the claim limitation is to be treated in accordance with 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. The presumption that the claim limitation is interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, is rebutted when the claim limitation recites sufficient structure, material, or acts to entirely perform the recited function.
Absence of the word “means” (or “step”) in a claim creates a rebuttable presumption that the claim limitation is not to be treated in accordance with 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph. The presumption that the claim limitation is not interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, is rebutted when the claim limitation recites function without reciting sufficient structure, material or acts to entirely perform the recited function.
Claim limitations in this application that use the word “means” (or “step”) are being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, except as otherwise indicated in an Office action. Conversely, claim limitations in this application that do not use the word “means” (or “step”) are not being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, except as otherwise indicated in an Office action.
Claim 28 recites the limitation “the facility comprises means for controlling the permeate side pressure in the first membrane separation unit” which meets the three-prong test, therefore invoking 35 U.S.C. 112(f). In ¶037 of the specification, the Applicant discloses that the structure that supports the recited function is a pressure regulating valve.
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.
Claim 43 is 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 43 recites the limitation “wherein the temperature of the first permeate stream is adjusted based on the measured concentration of methane in the third permeate stream.” There is insufficient antecedent basis for this limitation in the claim, as claim 43 depends upon claim 38, which does not establish a way to measure the concentration of methane in the third permeate stream. For the purpose of compact prosecution, the Examiner has interpreted this claim to be dependent upon claim 39 rather than claim 38.
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.
Claims 27-31 are rejected under 35 U.S.C. 103 as being unpatentable over Paget, and further in view of admitted prior art from the Applicant’s specification (¶044), Evonik Industries SEPURAN®Green membrane (hereinafter referred to as Evonik).
Regarding claim 27, Paget teaches a facility (Fig. 3) for separating methane and carbon dioxide from a gas stream (Col. 1, lines 17-20 “The present invention relates to a membrane permeation process for treating a gas stream containing at least methane and carbon dioxide”), the facility comprising: a compressor (Fig. 3, compressor 2); four membrane separation units (Fig. 3, membrane stages 4, 7, 10, and 13), each membrane separation unit comprising a gas separation membrane having higher permeance for carbon dioxide than for methane (Col. 3-4, steps (a), (b), (c), and (i) disclosing that the membranes are more permeable to carbon dioxide than to methane), a gas inlet (Fig. 3, arrows depict the direction of gas flow and the inlets of the membrane stages), a retentate outlet (Fig. 3, retentate 5, 8, 11, and 14) and a permeate outlet (Fig. 3, permeate 6, 9, 12, and 15); a methane oxidation unit (Col. 2, lines 60-63 “in general discharged to the atmosphere while optionally passing through an oxidizer in order to oxidize therein the residual methane”); a raw gas conduit connected to an inlet of the compressor (Fig. 3, biogas 1); a feed conduit connecting an outlet of the compressor with the gas inlet of the first membrane separation unit (Fig. 3, compressed biogas 3); a first retentate conduit connecting the retentate outlet of the first membrane separation unit to the gas inlet of the second membrane separation unit (Fig. 3, retentate 5 travels from first membrane stage 4 to second membrane stage 7); a second retentate conduit connected to the retentate outlet of the second membrane separation unit (Fig. 3, retentate 8 travels out of the second membrane stage 7); a first permeate conduit connecting the permeate outlet of the first membrane separation unit to the gas inlet of the third membrane separation unit (Fig. 3, permeate 6 travels from first membrane stage 4 to third membrane stage 10); a third retentate conduit connecting the retentate outlet of the third membrane separation unit to the gas inlet of the fourth membrane separation unit (Fig. 3, retentate 11 travels from third membrane stage 10 to fourth membrane stage 13); a fourth retentate conduit connecting the retentate outlet of the fourth membrane separation unit to an inlet of the compressor (Fig. 3, retentate 14 is recycled back from fourth membrane stage 13 to compressor 2); a second permeate conduit connecting the permeate outlet of the second membrane separation unit to an inlet of the compressor (Fig. 3, permeate 9 is recycled back from second membrane stage 7 to compressor 2); a third permeate conduit connected to the permeate outlet of the third membrane separation unit (Fig. 3, permeate 12 leaves third membrane stage 10); a fourth permeate conduit connected to the permeate outlet of the fourth membrane separation unit (Fig. 3, permeate 15 leaves fourth membrane stage 13); wherein: the third permeate conduit is configured to discharge the third permeate to the surrounding atmosphere (Col. 7, lines 10-12 “The third permeate 12 is in the form of a gas stream; it is discharged from the process in order to be used or released.”); the fourth permeate conduit connects the permeate outlet of the fourth membrane separation unit to the methane oxidation unit (Claim 5 “The process of claim 1, wherein the third and fourth permeates are either vented to atmosphere or treated in a thermal oxidizer.”); the first membrane separation unit comprises a membrane with selectivity for carbon dioxide over methane (Col. 3, lines 53-54 “said first membrane being more permeable to carbon dioxide than to methane”). Paget is silent on the exact gas selectivity of the membranes used and the concentration of carbon dioxide in the first permeate stream.
However, the instant specification states that the membrane modules and cartridges with a gas selectivity of carbon dioxide over methane, determined at 20⁰C and 5 bar, of at least 30, are commercially available from Evonik Fibres GmbH under the trade name SEPURAN®Green (¶0044 of Spec.). This is an admission that a membrane satisfying the claimed properties was on sale before the effective filing date of the instant application. As to the concentration of the carbon dioxide in the first permeate stream, a recitation of the intended use of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. When the structure recited in the reference is substantially identical to that of the claimed invention, claimed properties or functions are presumed to be inherent. If the prior art structure (in this scenario, the facility as taught by Paget with the Evonik membrane) is capable of performing the intended use, then it meets the claim. See MPEP § 2112.01(I).
Paget and Evonik are considered analogous to the claimed invention because they are in the same field of membrane separation for separating methane and carbon dioxide from a gas mixture. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the membrane separation units as taught by Paget could be modified to incorporate the membranes as taught by Evonik to produce a permeate stream that contains a specific concentration of carbon dioxide (90 to 99 % by volume). Additionally, a simple substitution of one known element for another to obtain predictable results (the separation of carbon dioxide and methane) supports a prima facie case of obviousness. See MPEP § 2143(I)(B).
Regarding claim 28, Paget and Evonik teach the facility as applied to claim 27 above. As to the concentration of the carbon dioxide in the first permeate stream, a recitation of the intended use of the claimed invention must result in a structural difference between the claimed invention and the prior art in order to patentably distinguish the claimed invention from the prior art. When the structure recited in the reference is substantially identical to that of the claimed invention, claimed properties or functions are presumed to be inherent. If the prior art structure (in this scenario, the facility as taught by Paget with the Evonik membrane) is capable of performing the intended use, then it meets the claim. See MPEP § 2112.01(I).
Regarding claim 29, Paget and Evonik teach the facility as applied to claim 27 above. Paget further teaches wherein the methane oxidation unit comprises a catalytic oxidizer, a regenerative thermal oxidizer or a biofilter (Claim 5 “The process of claim 1, wherein the third and fourth permeates are either vented to atmosphere or treated in a thermal oxidizer”).
Regarding claim 30, Paget and Evonik teach the facility as applied to claim 27 above. Paget further teaches wherein the first permeate conduit connects the permeate outlet of the first membrane separation unit to the gas inlet of the third membrane separation unit without any intermediary compressor or pump (Fig. 3, permeate 6 travels from first membrane stage 4 to third membrane stage 10 without the inclusion of an intermediary compressor or pump).
Regarding claim 31, Paget and Evonik teach the facility as applied to claim 27 above. Paget further teaches wherein at least one of the membranes has a different selectivity than the other three (Col. 5, lines 40-41 “at least one membrane separation unit uses a membrane of different selectivity”) and that the second permeate and fourth retentate are recycled back to the compressor and the first membrane stage (Col. 7, lines 46-49 “the fourth retentate 14 is sent back to the compressor 2 together with the second permeate 9 in order to be recompressed before supplying the first membrane stage.”). Paget discloses that the second permeate 9 is not rich in methane (Col. 6, lines 44-45) and that the fourth retentate 14 is enriched in methane (Col. 7,42-44). Paget is silent regarding whether the separation capacity of the second membrane differs from that of the fourth membrane.
However, in order for the second permeate to not be rich in methane (and subsequently rich in carbon dioxide, relatively) and the fourth retentate to be enriched in methane, it would have been obvious to one of ordinary skill in the art that this may be achieved by using a membrane with a higher separation capacity for carbon dioxide in the second membrane separation unit while using a membrane with a lower separation capacity for carbon dioxide in the fourth membrane separation unit to produce the desired concentrations for the recycled second permeate and fourth retentate.
Claim 32 is rejected under 35 U.S.C. 103 as being unpatentable over Paget and Evonik, and further in view of U.S. Patent Publication No. US 2021/0339189 A1 to Winkler (hereinafter referred to as Winkler).
Regarding claim 32, Paget and Evonik teach the facility as applied to claim 27 above. Paget and Evonik do not teach wherein a pressure regulating valve is arranged in the fourth retentate conduit.
However, Winkler teaches a control valve (Fig. 1, control valve 16) that is arranged in the third and final retentate conduit of Winkler’s invention, as Winkler teaches the use of only three membranes. Winkler additionally teaches wherein the control valve is placed to control the fraction of recycled gas being passed back to the initial compressor (¶0043 “The recycle conduit then also comprises at least one control valve for controlling the fraction of recycled gas being passed to recycle feed point”).
Paget, Evonik, and Winkler are considered analogous to the claimed invention because they are in the same field of membrane separation for separating methane and carbon dioxide from a gas mixture. It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the fourth retentate conduit as taught by Paget could be modified to incorporate the control valve as taught by Winkler in order to control the fraction of recycled gas being passed back to the initial compressor (¶0043 “The recycle conduit then also comprises at least one control valve for controlling the fraction of recycled gas being passed to recycle feed point”).
Claims 33-35 are rejected under 35 U.S.C. 103 as being unpatentable over Paget and Evonik as applied to claim 27 above, and further in view of Winkler and Japanese Patent Publication No. JP 2021088484 A to Sudo (hereinafter referred to as Sudo).
Regarding claim 33, Paget and Evonik teach the facility as applied to claim 27 above. Paget further teaches that third permeate is enriched in carbon dioxide (Col. 4, lines 22-23 “a third permeate that is enriched in carbon dioxide relative to the first permeate”) and that the third permeate may undergo additional treatment for an even further purified carbon dioxide stream (Col. 4, lines 43-46 “The third and fourth permeates are discharged from the process; they may – independently or together – before example treated by thermal oxidation, used for upgrading CO2”).
Winkler teaches the use of an oxygen concentration measurement to confirm that a gas being fed into an adsorber does not exceed a threshold concentration of oxygen (¶0017 “an oxygen concentration measurement on the feed line between the recycle feed point and the hydrogen sulfide adsorber, and two control valves, where the oxygen concentration in the gas fed to the hydrogen sulfide adsorber is maintained within a preset range.”). Paget, Evonik, and Winkler do not teach the use of a methane concentration sensor connected to the third permeate conduit.
However, Winkler demonstrates the use of concentration measurement devices to determine that the level of an undesirable gas (which is oxygen in the case of Winkler) does not exceed a threshold limit. Paget teaches that the third permeate is enriched in carbon dioxide and may undergo further processing to develop a higher concentration of carbon dioxide, indicating that at this step in the membrane separation process the methane should be adequately separated out from the carbon dioxide. It would be obvious to one of ordinary skill in the art that a methane concentration sensor may be beneficial in determining whether this separation has occurred before sending the carbon dioxide for further processing.
Furthermore, Sudo teaches a methane removal device (Abstract “To provide a technology capable of continuously performing appropriate methane removal”) that uses a sensor to determine if the removal of methane was sufficient (Pg. 16 “For example, using a sensor that detects methane … it is determined whether or not the desired combustion is achieved, and the combustion state is not appropriate, that is, it is determined that the removal of methane is insufficient”). Paget, Evonik, Winkler, and Sudo are considered analogous to the claimed invention because they are in the same field of separating methane out of a gas stream. It would have been obvious before the effective filing date of the claimed invention to modify the facility as taught by Paget and Evonik and Winkler to include a methane sensor as taught by Sudo to determine whether the methane had been adequately separated from the carbon dioxide, ensuring a concentrated stream of carbon dioxide could be sent for further processing.
Regarding claim 34, Paget, Evonik, Winkler, and Sudo teach the facility as applied to claim 33 above. Winkler further teaches a pressure regulating valve (¶0043 “The recycle conduit then also comprises at least one control valve for controlling the fraction of recycled gas being passed to recycle feed point”) and a controller controlling the pressure regulating valve based on data measured by a gas concentration sensor (¶0044 “and a controller which is configured to operate control valve(s) to maintain the oxygen concentration within a preset range.”). As explained above, it would have been obvious to modify the facility as taught by Paget and Evonik to incorporate a methane sensor as taught by Sudo. The addition of the pressure regulating valve and controller as taught by Winkler to control said methane sensor would allow for the methane concentration of the fourth retentate to fall within a predetermined range. It would have been obvious to one of ordinary skill in the art that the incorporation of a pressure regulating valve as taught by Winkler would allow for control and maintenance of the concentration of methane being recycled to the compressor through the fourth retentate.
Regarding claim 35, Paget, Evonik, Winkler, and Sudo teach the facility as applied to claim 33 above. Winkler further teaches a heat exchanger in the feed conduit (¶0030 “The device of the invention preferably also comprises a dehumidifier upstream of the first membrane separation stage … and preferably dehumidifies the compressed gas by cooling, condensing water from the cooled gas in a condenser and reheating the gas, with the reheating preferably carried out by the compressed gas in a counter current heat exchanger.”), a flow regulating valve controlling flow of a heating or cooling fluid to the heat exchanger and a controller controlling this flow regulating valve based on data measured by the gas sensor (¶0045 “In another further preferred embodiment, the device of the invention comprises a measurement of relative humidity … and a controller which is configured to operate control valve(s) to maintain the relative humidity within a preset range … Controlling relative humidity of the gas may be combined with controlling oxygen concentration so as to maintain both parameters within the ranges providing optimum performance of the hydrogen sulfide adsorber.”). Incorporating the heat exchanger and flow regulating valve as taught by Winkler with the facility as previous described would allow for the humidity of the gas stream to be monitored and adjusted according to a methane concentration sensor as taught by Sudo.
Claim 36 is rejected under 35 U.S.C. 103 as being unpatentable over Paget, Evonik, Winkler, and Sudo as applied to claim 33 above, and further in view of WO Patent Publication No. 2013/049109 to Collignon et al. (hereinafter referred to as Collignon).
Regarding claim 36, Paget, Evonik, Winkler, and Sudo teach the facility as applied to claim 33 above. Paget further teaches wherein the membrane separation units comprise a multitude of membrane modules arranged in parallel (Col. 3, lines 41-45 “A membrane or membrane stage should be understood to mean a single membrane or a bundle of membranes or a module composed of several bundles or of several modules as long as they are parallel with respect to one another.”). Paget, Evonik, Winkler, and Sudo do not teach a membrane module comprising shut-off valves blocking flow through the membrane module, or a controller controlling the shut-off valves based on data measured by methane concentration sensor.
However, Collignon teaches a membrane filtration system with a multitude of membrane modules (Pg. 7 “The membrane filtration systems may include multiple modules including headers that retain filtration cartridges within the individual modules”), wherein said membrane modules comprise shut-off valves blocking flow through the membrane module (Pg. 11 “In certain embodiments, the removable end cap may comprise a port and a shut-off valve.”), and a controller controlling the shut-off valves based on data measured by a sensor (Pg. 10 “A control system may be configured to compare a measured value against a target value or range of values. If the measure value(s) fails to meet the target value or values, then the control system may automatically engage a shut-off valve to halt the flow of filtrate through the module or cartridge.”).
Paget, Evonik, Winkler, Sudo, and Collignon are considered analogous to the claimed invention because they are in the same field of gas separation. Although Collignon does not teach a methane sensor, one of ordinary skill in the art may ascertain how the control system as taught by Collignon may be incorporated into the previously taught facility to control a shut-off valve within a membrane module. It therefore would have been obvious before the effective filing date of the claimed invention to modify the facility as taught by Paget, Winkler, and Sudo to include the membrane module as taught by Collignon to allow for the identification of a fault within said membrane module if the measured value of methane deviates from the target value and control the shut-off valve to stop flow through the module until corrective action is taken (Pg. 5 of Collignon “According to another aspect, evaluating may comprise measuring the at least one property, comparing the measured value with a target value, and identifying a fault in the at least one filtration module based on the comparison between the measured value and the target value.”).
Claims 38 and 45 are rejected under 35 U.S.C. 103 as being unpatentable over Paget and Evonik as applied to claim 27 above, and further in view of U.S. Patent No. 8999038 to Ungerank et al. (hereinafter referred to as Ungerank).
Regarding claim 38, Paget teaches a membrane process for separating methane and carbon dioxide from a gas stream (Col. 1, lines 17-20 “The present invention relates to a membrane permeation process for treating a gas stream containing at least methane and carbon dioxide”), comprising: providing the facility of claim 27 as taught by Paget and Evonik above, introducing a raw gas stream, containing from 20 to 60 % by volume, carbon dioxide (Col. 1, lines 46-49 “Depending on the organic matter degraded and the techniques used, the proportions of the components differ, but on average biogas comprises, as dry gas, from 30% to 75% methane, from 15% to 60% CO2, from 0 to 15% nitrogen, from 0 to 5% oxygen and trace compounds”) and having a combined content of methane and carbon dioxide of at least 95% by volume (Col. 1, lines 46-49; the raw gas stream may comprise from 30% to 75% methane and from 15% to 60% CO2, the raw gas stream is therefore capable of having a combined content of methane and carbon dioxide of at least 95% depending upon the type of gas stream being used), into the raw gas conduit of said facility (Fig. 3, biogas 1); compressing the raw gas stream combined with recycle streams from the fourth retentate conduit and the second permeate conduit (Fig. 3, biogas 1 is mixed with fourth retentate 14 and second permeate 9 before being compressed by compressor 2); separating the feed stream in the first membrane separation unit into a first permeate stream and a first retentate stream (Fig. 3, compressed biogas 3 supplies first membrane stage 4 to form first permeate 6 and first retentate 5), using a membrane with a selectivity for carbon dioxide over methane of at least 30 (see Evonik as applied to claim 27 above); separating the first retentate stream in the second membrane separation unit into a second retentate stream and a second permeate stream (Fig. 3, first retentate 5 supplies second membrane stage 7 to form second retentate 8 and second permeate 9), further processing the second retentate stream or withdrawing the second retentate stream as a methane rich product stream and recycling the second permeate stream through the second permeate conduit (Col. 6, lines 42-47 “Recovered at the outlet of this second membrane stage are a second retentate 8 that is under pressure and rich in methane and a second permeate 9 which is sent back to the compressor 2 in order to be recompressed before being recycled to the feed of the first membrane stage.”); separating the first permeate stream in the third membrane separation unit into a third retentate stream and a third permeate stream (Fig. 3, first permeate 6 supplies third membrane stage 10 to form third retentate 11 and third permeate 12), discharging the third permeate stream to the surrounding atmosphere without further methane removal (Col. 7, lines 10-12 “The third permeate 12 is in the form of a gas stream; it is discharged from the process in order to be used or released.”); separating the third retentate stream in the fourth membrane separation unit into a fourth retentate stream and a fourth permeate stream (Fig. 3, third retentate 11 supplies fourth membrane stage 13 to form fourth retentate 14 and fourth permeate 15), recycling the fourth retentate stream through the retentate conduit (Col. 7, lines 46-49 “the fourth retentate 14 is sent back to the compressor 2 together with the second permeate 9 in order to be recompressed”); and oxidizing the fourth permeate stream in the methane oxidation unit (Claim 5 “The process of claim 1, wherein the third and fourth permeates are either vented to atmosphere or treated in a thermal oxidizer.”). Paget and Evonik are silent on the specific experimentation parameters, and does therefore do not teach the steps of providing a feed stream at a feed pressure of from 7 to 25 bar and a temperature of from 15 to 50⁰C, selecting permeate side pressure in the first membrane separation unit and separation capacities in the four membrane separation units to provide a carbon dioxide concentration in the first permeate stream of from 90 to 99% by volume, or providing an off-gas stream containing less than 0.3% by volume methane.
However, Ungerank teaches a process for gas separation using membrane modules (Fig. 11), wherein the feed stream is compressed to a pressure of 7 to 25 bar (Col. 5, lines 8-13 “In a preferred configuration of the present invention, a compressor (4) brings the crude gas mixture … to the desired pressure range from 5 to 100 bar, but preferably to a pressure of 9 to 75 bar.) and a temperature of from 15 to 50⁰C (Col. 10, lines 32-33 “The gas which has been compressed and cooled to 20⁰C. is applied to the feed stream separation stage”); and selecting separation capacities in the membrane separation units to provide a carbon dioxide concentration in the first permeate stream of from 90 to 99 % by volume (Col. 10, lines 49-51 “The permeate of the feed stream separation stage has a … carbon dioxide content of 91.0% and a methane content of 9.0%”). Ungerank further teaches that said process produces a third permeate stream with a composition of 99.5% carbon dioxide and only 0.5% methane (Col. 14, lines 29-31 “This gives a third permeate stream … with a composition of 99.5% carbon dioxide and only 0.5% methane.”). Although Ungerank does not teach a fourth membrane separation unit, the modification of the facility as taught by Paget and Evonik to incorporate the methane and experimentation parameters of Ungerank would allow for the fourth permeate to provide a stream of even less than 0.5% methane, as this is the concentration reported by Ungerank when using only three membrane separation stages. Furthermore, for one of ordinary skill in the art it would have been obvious to adjust the experimentation parameters of the entire apparatus to produce an off-gas stream with the smallest volume of methane as possible, as this is a known greenhouse gas. Before releasing the off-gas stream to the surrounding atmosphere, routine experimentation would be conducted to release the smallest amount of methane possible (Col. 13, lines 52-53 “In order to satisfy various legislators, it is necessary to minimize the methane loss into the atmosphere.”).
Paget, Evonik, and Ungerank are considered analogous to the claimed invention because they are in the same field of gas separation using membrane separation modules. It would have been obvious to one of ordinary skill in the art to modify the facility as taught by Paget and Evonik to incorporate the membrane and experimentation parameters as taught by Ungerank to optimize the separation of carbon dioxide and methane. Furthermore, although the prior art does not specifically teach that the off-gas stream would contain 0.3% by volume methane, the optimum or workable ranges would be discovered through routine experimentation and are therefore not considered inventive. See MPEP § 2144.05 (II)(A).
Regarding claim 45, Paget, Evonik, and Ungerank teach the process as applied to claim 38 above. Paget further teaches that the feed pressure is compressed to a pressure of P1 (Col. 7, lines 16-18 “the biogas to be purified 1 is compressed by the compressor 2; the compressed biogas 3 at a pressure P1 supplies the first membrane stage”) and that the first retentate and first permeate are recovered, wherein the first retentate is at a pressure close to P1 (Col. 7, lines 20-22 “Recovered at the outlet of this first membrane stage are a first retentate 5 at a pressure close to P1, and a first permeate 6.”). Paget is otherwise silent on the pressure of the third separation unit.
However, it is known that a pressure drop will occur as a gas passes through each membrane stage. The pressure ratio must be adequate to continue the flow of the first permeate through the third membrane separation stage without the use of intermediate compression (Col. 7, lines 30-32 “The first permeate 6 is in the form of a gas stream; it supplies – without intermediate compression – a third membrane stage referenced 10”). Without the use of intermediate compression, the pressure ratio of the first membrane separation stage and the third membrane separation stage must be similar enough to one another that the gas will continue to flow through not only the third membrane separation stage but also through the fourth membrane separation stage. However, it is likely this pressure ratio will be slightly lower after passing through the first membrane separation stage as the pressure of the first permeate (the feed side pressure for the third membrane separation stage) would also be lower than the initial pressure of P1 (the feed side pressure for the first membrane separation stage). 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 the case of Paget, this workable range would have to be established in order for the gas to continue to flow through the third and fourth membrane separation stages without the use of intermediate compression. See MPEP § 2144.05 (II)(A).
Claim 44 is rejected under 35 U.S.C. 103 as being unpatentable over Paget, Evonik, and Ungerank as applied to claim 38 above, and further in view of Winkler.
Regarding claim 44, Paget, Evonik, and Ungerank teach the process as applied to claim 38 above. Paget, Evonik, and Ungerank do not teach wherein the separation capacity of the second membrane separation unit is selected to provide a carbon dioxide concentration in the second retentate stream of from 0.5 to 4.0% by volume and the separation capacity of the fourth membrane separation unit is selected to provide a methane recovery with the second retentate stream of from 98.0 to 99.9%.
However, Winkler teaches wherein the separation capacity of a second membrane separation unit is selected to provide a carbon dioxide concentration in a second retentate stream of from 0.5 to 4.0 % by volume and a methane recovery of from 98.0 to 99.9 % (¶0061 “The second membrane separation stage separates the first retentate into 4715 Nm3/h of a second retentate, obtained at 11.0 bar, containing 93.6 vol-% methane, 1.6 vol-% carbon dioxide”).
Paget, Evonik, Ungerank, and Winkler are considered analogous to the claimed invention because they are in the same field of gas separation using membrane separation modules. Although Paget is silent on the concentration of methane in the second retentate 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 membrane separation units as taught by Paget and Evonik could be modified to incorporate the membranes of a specific gas selectivity as taught by Winkler to produce a permeate stream that contains a specific concentration of carbon dioxide (90 to 99 % by volume).
Claims 39 and 42-43 are rejected under 35 U.S.C. 103 as being unpatentable over Paget, Evonik, and Ungerank as applied to claim 38 above, and further in view of Sudo.
Regarding claim 39, Paget, Evonik, and Ungerank teach the process as applied to claim 38 above. Paget further teaches that third permeate is enriched in carbon dioxide (Col. 4, lines 22-23 “a third permeate that is enriched in carbon dioxide relative to the first permeate”) and that the third permeate may undergo additional treatment for an even further purified carbon dioxide stream (Col. 4, lines 43-46 “The third and fourth permeates are discharged from the process; they may – independently or together – before example treated by thermal oxidation, used for upgrading CO2”). Paget, Evonik, and Ungerank do not teach the use of a methane concentration sensor connected to the third permeate conduit. However, Paget teaches that the third permeate is enriched in carbon dioxide and may undergo further processing to develop a higher concentration of carbon dioxide, indicating that at this step in the membrane separation process the methane should be adequately separated out from the carbon dioxide. It would be obvious to one of ordinary skill in the art that a methane concentration sensor may be beneficial in determining whether this separation has occurred before sending the carbon dioxide for further processing.
Furthermore, Sudo teaches a methane removal device (Abstract “To provide a technology capable of continuously performing appropriate methane removal”) that uses a sensor to determine if the removal of methane was sufficient (Pg. 16 “For example, using a sensor that detects methane … it is determined whether or not the desired combustion is achieved, and the combustion state is not appropriate, that is, it is determined that the removal of methane is insufficient”).
Paget, Evonik, Ungerank, and Sudo are considered analogous to the claimed invention because they are in the same field of separating methane out of a gas stream. 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 process as taught by Paget, Evonik, and Ungerank to include a methane sensor as taught by Sudo to determine whether the methane had been adequately separated from the carbon dioxide, ensuring a concentrated stream of carbon dioxide could be sent for further processing.
Regarding claim 42, Paget, Evonik, Ungerank, and Sudo teach the process as applied to claim 39 above. Paget further teaches that third permeate is enriched in carbon dioxide (Col. 4, lines 22-23 “a third permeate that is enriched in carbon dioxide relative to the first permeate”) and that the third permeate may undergo additional treatment for an even further purified carbon dioxide stream (Col. 4, lines 43-46 “The third and fourth permeates are discharged from the process; they may – independently or together – before example treated by thermal oxidation, used for upgrading CO2”). As explained above, it would have been obvious to incorporate a methane sensor as taught by Sudo to determine whether the methane has been adequately separated from the carbon dioxide, ensuring a concentrated stream of carbon dioxide can be sent for further purification. Paget does not disclose wherein the temperature of the feed stream is adjusted based on the measured concentration of methane in the third permeate stream, decreasing the temperature of the feed stream when the concentration of methane in the third permeate stream rises to above the target value. However, it is not inventive to discover the optimum or workable ranges by routine experimentation. In the case of Paget, this workable range would have to be established in order to adequately remove the methane from the third permeate stream. See MPEP § 2144.05 (II)(A).
Regarding claim 43, Paget, Evonik, Ungerank, and Sudo teach the process as applied to claim 39 above. Paget further teaches that third permeate is enriched in carbon dioxide (Col. 4, lines 22-23 “a third permeate that is enriched in carbon dioxide relative to the first permeate”) and that the third permeate may undergo additional treatment for an even further purified carbon dioxide stream (Col. 4, lines 43-46 “The third and fourth permeates are discharged from the process; they may – independently or together – before example treated by thermal oxidation, used for upgrading CO2”). As explained above, it would have been obvious to incorporate a methane sensor as taught by Sudo to determine whether the methane has been adequately separated from the carbon dioxide, ensuring a concentrated stream of carbon dioxide can be sent for further purification. Paget does not disclose wherein the temperature of the first permeate stream is adjusted based on the measured concentration of methane in the third permeate stream, decreasing the temperature of the first permeate stream when the concentration of methane in the third permeate stream rises to above the target value. However, it is not inventive to discover the optimum or workable ranges by routine experimentation. In the case of Paget, this workable range would have to be established in order to adequately remove the methane from the third permeate stream. See MPEP § 2144.05 (II)(A).
Claims 40-41 are rejected under 35 U.S.C. 103 as being unpatentable over Paget, Evonik, Ungerank, and Sudo as applied to claim 39 above, and further in view of Winkler.
Regarding claim 40, Paget, Evonik, Ungerank, and Sudo teach the process as applied to claim 38 above.
Winkler teaches a pressure regulating valve (¶0043 “The recycle conduit then also comprises at least one control valve for controlling the fraction of recycled gas being passed to recycle feed point”) and a controller controlling the pressure regulating valve based on data measured by a gas concentration sensor (¶0044 “and a controller which is configured to operate control valve(s) to maintain the oxygen concentration within a preset range.”).
As explained above, it would have been obvious to modify the process as taught by Paget, Evonik, and Ungerank to incorporate a methane sensor as taught by Sudo. Paget teaches that the third permeate is enriched in carbon dioxide and may undergo further processing to develop a higher concentration of carbon dioxide, indicating that at this step in the membrane separation process the methane should be adequately separated out from the carbon dioxide. It would be obvious to one of ordinary skill in the art that a methane concentration sensor may be beneficial in determining whether this separation has occurred before sending the carbon dioxide for further processing. The addition of the pressure regulating valve and controller as taught by Winkler to control said methane sensor would allow for the methane concentration of the third retentate to fall within a predetermined range. It would have been obvious to one of ordinary skill in the art that the incorporation of a pressure regulating valve as taught by Winkler would allow for control and maintenance of the concentration of methane within the third permeate before sending the permeate for further processing or releasing it into the atmosphere.
Regarding claim 41, Paget, Evonik, Ungerank, Sudo, and Winkler teach the process as applied to claim 40 above. Winkler further teaches a control valve (Fig. 1, control valve 16) that is arranged in the third and final retentate conduit of Winkler’s invention, as Winkler teaches the use of only three membranes. However, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention that the fourth retentate conduit as taught by Paget could be modified to incorporate the control valve as taught by Winkler in order to control the fraction of recycled gas being passed back to the initial compressor (¶0043 “The recycle conduit then also comprises at least one control valve for controlling the fraction of recycled gas being passed to recycle feed point”). The fraction of recycled gas being passed back to the initial compressor would subsequently control the permeate side pressure of the first membrane separation unit based upon the amount and flow rate of the gas being recycled.
Claim 46 is rejected under 35 U.S.C. 103 as being unpatentable over Paget, Evonik, and Ungerank as applied to claim 38 above, as evidenced by SCHASER, N. Optimizing your Thermal Oxidizer to Save Energy and Operating Costs through Heat Recovery [online], December 2017. Retrieved from the Internet: <URL: https://www.durr.com/en/media/news/news-detail/view/optimizing-your-thermal-oxidizer-to-save-energy-and-operating-costs-through-heat-recovery-846> (hereinafter referred to as Schaser).
Regarding claim 46, Paget, Winkler, and Ungerank teach the process as applied to claim 38 above. Paget further teaches wherein the third and fourth permeates are treated in a thermal oxidizer (Claim 5 “wherein the third and fourth permeates are either vented to atmosphere or treated in a thermal oxidizer.”). Paget is silent on additional details regarding the oxidation process.
As evidenced by Schaser, regenerative thermal oxidizers were developed to optimize the usage of energy. Furthermore, Schaser discloses that if the concentration of the compound entering the combustion chamber (in the case of Paget, methane) is high enough, the operation becomes autothermal. Autothermal operation of the oxidizer allows for a self-sustaining reaction that can further optimize the usage of energy. It therefore would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention for the thermal oxidizer as disclosed by Paget to include a regenerative thermal oxidizer and to furthermore provide a methane concentration in the fourth permeate stream which would allow for autothermal operation of said oxidizer.
Allowable Subject Matter
Claim 47 is allowed.
The following is an examiner’s statement of reasons for allowance:
Claim 47 requires a facility for separating methane and carbon dioxide from a gas stream, wherein the facility comprises all components of claim 27 (claim 47 is not dependent upon claim 27 but rather this reference is made for simplicity), a first membrane separation unit comprised of a bore-side fed hollow fiber membrane module with a gas inlet, a retentate outlet, a permeate outlet, and an additional permeate outlet that is connected to the fourth membrane separation unit through an additional conduit. Furthermore, claim 47 requires a flow regulating valve in the additional conduit that is controlled based on data measured by a methane concentration sensor.
The prior art which best approaches the invention of claim 47 is Paget, Evonik, and Sudo, wherein Paget and Evonik teach a facility for separating methane and carbon dioxide from a gas stream, the facility comprising the limitations of claim 27 as explained above, wherein the first membrane separation unit comprises a bore-side fed hollow fiber membrane module that contains a gas inlet, a retentate outlet, and a permeate outlet. Paget, Evonik, and Sudo also teach a methane concentration sensor and a controller configured to alter the experimentation parameters of the facility based on data measured by the methane concentration sensor.
However, Paget, Evonik, and Sudo nor the related prior art provide an additional permeate outlet connected to a fourth membrane separation unit through an additional conduit and a flow regulating valve arranged in the additional conduit that is controlled through a controller based on data measured by the methane concentration sensor. Furthermore, neither Paget, Evonik, Sudo, nor the related prior art provide a rationale for modifying any of the previously discussed teachings to meet the requirements as set forth by claim 47.
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Conclusion
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/RACHEL MARIE SLAUGOVSKY/Examiner, Art Unit 1776
/Jennifer Dieterle/Supervisory Patent Examiner, Art Unit 1776