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
This action is responsive to the Amendment and Remarks filed on July 20, 2026. The Amendment has been entered.
Claims 2, 3, 9, 10 and 11 have been cancelled. Claims 1, 6, 8, 12, 15, 16 and 19 have been amended. Claims 1, 4–8 and 12–20 are pending and are examined herein, of which claims 1 and 12 are independent.
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.
This application includes one or more claim limitations that do not use the word “means,” but are nonetheless being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, because the claim limitation(s) uses a generic placeholder that is coupled with functional language without reciting sufficient structure to perform the recited function and the generic placeholder is not preceded by a structural modifier. Such claim limitation(s) is/are:
“a cooling assembly” in claims 1 and 12, and “a first cooling assembly,” “a second cooling assembly” and “another cooling assembly” in claims 6, 7, 15, 18 and 19. The term “assembly” is a generic placeholder coupled with the functional language “to bring a temperature of the stream down to an initial cooling temperature between the initial mean temperature and a de-sublimation temperature for the carbon dioxide gas in the stream” without reciting sufficient structure to perform that function. The corresponding structure disclosed in the specification is an air cooler 130 and/or a chiller 140 (¶ 0015; Fig. 1) for the first cooling assembly, and a recuperator/heat exchanger 170, 425 (¶ 0016, 0023; Figs. 1, 4B) for the second and other cooling assemblies, and equivalents thereof.
Because this/these claim limitation(s) is/are being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, it/they is/are being interpreted to cover the corresponding structure described in the specification as performing the claimed function, and equivalents thereof.
If applicant does not intend to have this/these limitation(s) interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph, applicant may: (1) amend the claim limitation(s) to avoid it/them being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph (e.g., by reciting sufficient structure to perform the claimed function); or (2) present a sufficient showing that the claim limitation(s) recite(s) sufficient structure to perform the claimed function so as to avoid it/them being interpreted under 35 U.S.C. 112(f) or pre-AIA 35 U.S.C. 112, sixth paragraph.
Claim Interpretation – Broadest Reasonable Interpretation
“Condensing turbine”
The specification does not expressly define “condensing turbine.” Paragraph 0019 states that “the work extraction mechanism 185 may constitute a dynamic working device such as a condensing turbine.” Paragraph 0014 identifies that same work extraction mechanism 185 as being “such as a turbo-expander,” which “presents a volumetric effect on the received gas stream to cool and condense without reliance on a cooling surface to achieve the cooling and condensation.” Paragraph 0022 states “Where the work extraction mechanism 185 is a condensing turbine, operating at similar low temperature and mechanics to the second compressor 400 . . . .” Now-cancelled claim 3 recited that “the dynamic mechanism is one of a condensing turbine and a turbo-expander,” thereby placing both devices within the single genus of a “dynamic mechanism” performing the recited work-extraction and CO₂-solidification function.
Reading these disclosures together and in light of the specification as a whole, the broadest reasonable interpretation of “condensing turbine” is a turbomachine having at least one rotating element that extracts work from an expanding process stream, and in which at least a portion of the process stream changes phase from a vapor to a condensed phase (liquid and/or solid) as a result of that expansion within the machine. The term is not limited to the steam-plant usage in which “condensing turbine” denotes a turbine exhausting to a sub-atmospheric surface condenser; the specification nowhere describes, and the drawings nowhere depict, such an arrangement, and adopting that narrower construction would leave the recited element without written description support in the specification as filed. See MPEP §§ 2111, 2111.01.
“Piston”
Consistent with ¶ 0019 (“a positive displacement device such as a piston or other volumetric affecting device may also be utilized to extract work through a moving boundary”), “piston” is interpreted under the broadest reasonable interpretation as a positive-displacement reciprocating element that extracts work from the process stream by way of a moving boundary.
Claim Rejections - 35 USC § 112
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, 4–8 and 12–20 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 “one of a condensing turbine and a piston fluidly coupled to the cooling assembly to condense the carbon dioxide from the stream into a solid form by work extraction.” Claim 12 recites “solidifying carbon dioxide from the stream with one of a condensing turbine and a piston.”
The Examiner acknowledges that the Amendment has narrowed the scope of the prior enablement rejection. The functional recitation “in a manner facilitating a discouraging of surface accretion within the system” has been deleted, and the enablement rejection is no longer maintained as to that functional language or as to the previously recited genus “volumetric affecting device.” The rejection is maintained, however, as to the recited alternative of a “piston.” A claim that recites alternatives must be enabled for each alternative recited; enablement of one alternative does not enable the others. See MPEP §§ 2164.08, 2164.08(b). The claims as amended still require that a piston, standing alone, receive the cooled process stream and desublimate carbon dioxide from that stream into a solid form by work extraction.
The enablement inquiry asks whether, based on the specification’s disclosure, one skilled in the art could make and use the full scope of the claimed invention without undue experimentation. Wands factors relevant to this inquiry include: (1) the quantity of experimentation necessary; (2) the amount of direction or guidance presented in the specification; (3) the presence or absence of working examples; (4) the nature of the invention; (5) the state of the prior art; (6) the relative skill of those in the art; (7) the predictability or unpredictability of the art; and (8) the breadth of the claims. In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988); MPEP § 2164.01. The Examiner applies each Wands factor below as directed to the recited “piston” alternative.
Wands Factor (1): Quantity of Experimentation Necessary. The entirety of the specification’s disclosure regarding a piston is a single sentence at ¶ 0019: “However, a positive displacement device such as a piston or other volumetric affecting device may also be utilized to extract work through a moving boundary as opposed to inducing a dramatic temperature variation in order to achieve the sought degree of de-sublimation for solidifying the carbon dioxide.” The specification provides no swept volume or displacement, no expansion ratio, no valve timing or valve arrangement, no cycle rate, no clearance volume, no inlet and outlet pressure conditions, no sealing arrangement suitable for cryogenic service, and no means for evacuating accumulated solid carbon dioxide from the cylinder between strokes. Paragraph 0017 requires that the stream enter the device at approximately –85° C. and leave it at less than about –120° C.; the specification does not disclose any relationship between piston geometry or operating parameters and the attainment of that temperature drop. A practitioner would be required to conduct substantial experimental investigation to determine what reciprocating configuration achieves the claimed solidification for a continuously flowing, solids-laden industrial exhaust stream. This factor weighs against enablement.
Wands Factor (2): Amount of Direction or Guidance in the Specification. Apart from the single sentence of ¶ 0019, the specification contains no direction or guidance concerning a piston. Every figure of the application (Figs. 1, 2, 4A and 4B) depicts the same work extraction mechanism 185 described as a turbo-expander or condensing turbine (¶ 0014, 0019, 0022), and the flow-chart of Fig. 5 (¶ 0025–0026) is described only in terms of a generic “work extraction mechanism.” No guidance is provided on how a reciprocating, intermittent-flow machine is to be integrated into the continuous flow path of Fig. 1 (compressor 120 → air cooler 130 → chiller 140 → separator 145 → dryer 155 → recuperator 170 → mechanism 185 → separator 190), nor on how solid carbon dioxide formed within a closed cylinder is transferred to mechanical separator 190. This factor weighs against enablement.
Wands Factor (3): Presence or Absence of Working Examples. The specification contains no working example, no experimental data and no prophetic example of a piston used to desublimate carbon dioxide from a gas stream. The only embodiment described in operational terms is the turbo-expander/condensing turbine embodiment of ¶¶ 0013–0020. This factor weighs against enablement.
Wands Factor (4): Nature of the Invention. The invention is a continuous-flow cryogenic separation system that receives an industrial exhaust or flue gas stream and forms solid carbon dioxide at temperatures below approximately –56.6° C. and, per ¶ 0017, below about –120° C. A positive-displacement reciprocating machine is an intermittent-flow, volumetrically limited device whose operating principles differ materially from those of the continuously flowing turbomachine that the specification describes. The nature of the invention as a continuously operating, high-volume cryogenic process weighs against a finding that the single-sentence reference to a piston enables that alternative.
Wands Factor (5): State of the Prior Art. The prior art of record confirms that the formation of solid carbon dioxide within an expansion machine is a recognized and non-trivial design problem requiring purposeful structural measures. See Lissianski et al. (US 2015/0033792 A1) ¶¶ 0047–0049 (non-stick coatings on rotating components, electrically heated stationary blades, and internal gas flow channels to preclude adhesion of solid CO₂); Lockwood et al. (US 2011/0302955 A1) ¶¶ 0037–0038 and 0115–0119 (polished and coated surfaces, surface heating to limit heterogeneous nucleation, titanium construction for erosion resistance, and injection of a sweeping gas to prevent solids accumulation behind the impeller). The art addresses these measures exclusively in the context of turbomachinery, and no reference of record discloses a reciprocating piston used to desublimate carbon dioxide from a process stream. The state of the art therefore supplies no counterpart body of knowledge from which a skilled artisan could supply what the specification omits with respect to the piston alternative. This factor weighs against enablement.
Wands Factor (6): Relative Skill of Those in the Art. The field of cryogenic gas processing requires highly specialized engineering expertise, and one of ordinary skill would be familiar with positive-displacement expanders as a class. However, a high level of skill in the art does not substitute for enabling disclosure where the specification supplies no design criteria whatsoever for the claimed alternative, particularly as to the handling of a desublimating, solids-forming stream within a reciprocating cylinder. See MPEP § 2164.05(b). This factor is neutral to slightly against enablement.
Wands Factor (7): Predictability or Unpredictability of the Art. Cryogenic phase-change processes involving solid carbon dioxide formation are recognized in the art as relatively unpredictable; outcomes depend sensitively on inlet gas composition, pressure, temperature, expansion dynamics, flow geometry and surface conditions. The express anti-accretion and anti-erosion measures disclosed in Lissianski (¶¶ 0047–0049) and Lockwood (¶¶ 0115–0119) confirm this unpredictability. This factor weighs against enablement.
Wands Factor (8): Breadth of the Claims. Claims 1 and 12, and every claim depending therefrom, recite the piston as a full alternative to the condensing turbine, and therefore claim the piston embodiment in its entirety. The enabling disclosure of the specification extends only to the turbo-expander/condensing turbine embodiment. This factor weighs against enablement.
On balance, application of the Wands factors establishes that the specification does not enable one of ordinary skill in the art to make and use the full scope of the claimed invention without undue experimentation. The claims recite, as an express alternative, a piston that condenses carbon dioxide from the stream into a solid form by work extraction, while the specification provides only a single conclusory sentence identifying a piston as a possibility, without structural detail, operating parameters, working examples or design criteria. Stating a desired functional outcome, or naming a device as a possible alternative, without corresponding enabling disclosure does not satisfy § 112(a). See Sitrick v. Dreamworks, LLC, 516 F.3d 993, 999 (Fed. Cir. 2008); Auto. Techs. Int’l, Inc. v. BMW of N. Am., Inc., 501 F.3d 1274, 1283 (Fed. Cir. 2007); MPEP §§ 2164.01(a), 2164.04, 2164.08.
Claims 4–8 and 13–20 are also rejected under 35 U.S.C. 112(a) for being dependent upon a rejected claim.
Applicant may overcome this rejection by amending claims 1 and 12 to delete the “piston” alternative and to recite the condensing turbine alone, which the Examiner considers to be enabled by the disclosure.
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 15 and 16 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 15 recites “directing an emission of the stream from a separator coupled to the volumetric affecting device to a second compressor . . . .” There is insufficient antecedent basis for the limitation “the volumetric affecting device” in the claim. Claim 12, from which claim 15 depends by way of claim 13, no longer recites a “volumetric affecting device”; that element was replaced by amendment with “one of a condensing turbine and a piston.” The indefiniteness is compounded by the fact that the very same claim later recites “another cooling assembly fluidly coupled to the one of the condensing turbine and the piston,” so that it cannot be determined whether the separator of claim 15 is coupled to the device recited in claim 12 or to some additional, unrecited device. For purposes of examination on the merits, and consistent with the evident intent of the Amendment, the recitation “the volumetric affecting device” in claim 15 is treated as “the one of the condensing turbine and the piston” of claim 12.
Claim 16 is also rejected under 35 U.S.C. 112(b) for being dependent upon a rejected claim.
Preliminary Note: “Condensing Turbine” Analysis as Applied to Lissianski
Applicant argues that the amended recitation of “one of a condensing turbine and a piston” is not taught by Lissianski. The Examiner disagrees for three independent reasons, each of which is separately sufficient to establish that Lissianski’s multi-phase turbo expander 30/70 is a “condensing turbine.”
First, Lissianski’s expander is structurally a turbine. Lissianski expressly defines the term: “The term ‘multi-phase turbo expander’ as used herein refers to a radial, axial, or mixed flow turbo-machine through which a gas or gas mixture is expanded to produce work and additional output components” (¶ 0040). The device includes a housing 72, at least one rotating component (rotor) 74 “configured to extract work from a flow stream,” at least one stationary component 76 that “may include a stator or a nozzle,” seals 78, stationary blades 80 and rotor blades 82 (¶ 0041; Figs. 3, 4). These are the structural elements of a turbine.
Second, condensation of the working fluid occurs inside that turbine. Lissianski states that “Cooling the gas stream 86 in the multi-phase turbo expander 70 results in formation of a CH₄ vapor, LNG, and one or both of solid CO₂ and liquid CO₂ in the multi-phase turbo expander 70” (¶ 0045) (emphasis added), and that “the expansion process further cools the cooled compressed discharge stream 32 . . . generating the expanded exhaust stream 34 comprising a mixture of a vapor stream comprised substantially of CH₄ and a LNG/ice/solid CO₂ slurry” (¶ 0029). Lissianski further teaches that the temperature reduction is achieved “primarily as a result of work extraction in the multi-phase turbo expander 30” (¶ 0029). A turbine in which the expanding working fluid changes phase from vapor to liquid and solid, as a result of work extraction within the machine, is a condensing turbine under the broadest reasonable interpretation set forth above.
Third, the instant specification itself treats the two terms as denoting the same device. Paragraph 0014 identifies the work extraction mechanism 185 as “such as a turbo-expander,” and ¶ 0019 identifies the same mechanism 185 as “a dynamic working device such as a condensing turbine.” Now-cancelled claim 3 recited “the dynamic mechanism is one of a condensing turbine and a turbo-expander,” expressly grouping the two as alternative species of a single genus performing the identical recited function. Applicant cannot rely on a distinction between a “condensing turbine” and a “turbo-expander” that the specification and the original claims do not draw. See MPEP § 2111.01.
Claim Rejections - 35 USC § 102
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 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.
Claim(s) 1, 5, 8 and 12–16 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Lissianski et al. (US 2015/0033792 A1).
In regard to claim 1, Lissianski teaches a cryogenic-based carbon dioxide capture system (LNG production system 10) comprising:
an exhaust line (natural gas inlet 14 and the line conveying the stream to moisture removal device 12 and compression stage 100) for channeling a gas stream (16), the gas stream (16) having an initial mean temperature (the initial temperature of stream 16 as introduced into system 10) and including carbon dioxide gas (¶ 0018, 0022–0024, 0029, 0043; figs. 1, 2);
a cooling assembly (cooling stage 200 comprising air cooler 29 and heat exchanger 24) fluidly coupled to the exhaust line (14/16) to bring a temperature of the stream (16/21) down to an initial cooling temperature (approximately –40° C. at the discharge of heat exchanger 24) between the initial mean temperature and a de-sublimation temperature for the carbon dioxide gas in the stream (¶ 0024, 0027–0028, 0039; figs. 1, 2); and
one of a condensing turbine (multi-phase turbo expander 30, shown in detail at 70, comprising housing 72, work-extracting rotor 74, stator/nozzle 76, stationary blades 80 and rotor blades 82) and a piston fluidly coupled to the cooling assembly (24) to condense the carbon dioxide from the stream (32) into a solid form (the solid CO₂ of the LNG/ice/solid CO₂ slurry of expanded exhaust stream 34) by work extraction (the temperature of the stream being decreased during the expansion process primarily as a result of work extraction in the expander 30, the recovered energy being applied to the compression stage 100 by way of common shaft 36) (¶ 0029, 0040–0041, 0045; figs. 1–4).
The expander (30/70) is a condensing turbine for the reasons set forth in the Preliminary Note above. As claims 1 and 12 recite alternatives, disclosure of the condensing turbine alone meets this limitation, and disclosure of a piston is not required. See MPEP §§ 2117, 2131. The disclosed air cooler (29) and heat exchanger (24) are further the same structures as, or structural equivalents of, the air cooler (130) and chiller (140) identified as the corresponding structure for the “cooling assembly” limitation under 35 U.S.C. 112(f) (specification ¶ 0015).
In regard to claim 5, Lissianski teaches the cryogenic-based carbon dioxide capture system of claim 1 wherein the cooling assembly (cooling stage 200) comprises one of an air cooler (29, providing NG cooling after the last compression stage of multi-stage compressor 26) and a chiller (heat exchanger 24, cooled using a cooling medium, cooling air and/or cooling water, and optional intercoolers) (¶ 0027–0028; figs. 1, 2).
In regard to claim 8, Lissianski teaches the cryogenic-based carbon dioxide capture system of claim 1 further comprising a separator (38) coupled to the one of the condensing turbine and the piston (30) to divert solidified carbon dioxide (the solid CO₂ of LNG/ice/solid CO₂ slurry stream 42, further separated at liquid/solid separator 50 into LNG output stream 52 and output stream 54 comprised substantially of ice/solid CO₂) from the stream (34) and provide a substantially carbon-free emission (vapor stream 40 comprised substantially of CH₄) for management (recirculation along path 501 of recirculation stage 500) (¶ 0031–0034, 0038; figs. 1, 2).
In regard to claim 12, Lissianski teaches a method of cryogenic-based carbon capture from an exhaust gas stream in a system (10), the method comprising:
channeling the exhaust gas stream (16/21) with an initial mean temperature to a cooling assembly (cooling stage 200 comprising air cooler 29 and heat exchanger 24) of the system (10) to bring a temperature thereof down to an initial cooling temperature (approximately –40° C.) between the initial mean temperature and a de-sublimation temperature for the carbon dioxide gas in the stream (¶ 0022–0028, 0039, 0053; figs. 1, 2, 5); and
solidifying carbon dioxide (the solid CO₂ formed within expander 70) from the stream (32) with one of a condensing turbine (multi-phase turbo expander 30/70) and a piston (¶ 0029, 0045, 0053; figs. 1–5).
In regard to claim 13, Lissianski teaches the method of claim 12 further comprising compressing the stream (16/20) at a compressor (first compressor 22, which may comprise multi-stage compressor 26 with inter-stage cooling) in advance of the channeling to the cooling assembly (29, 24) (¶ 0025–0027, 0036; figs. 1, 2).
In regard to claim 14, Lissianski teaches the method of claim 13 wherein the initial cooling temperature of the stream (21) is achieved with one of an air cooler (29) and a chiller (heat exchanger 24) (¶ 0027–0028; figs. 1, 2).
In regard to claim 15, Lissianski teaches the method of claim 13 wherein the compressor is a first compressor (22) and the method further comprises directing an emission of the stream (vapor stream 40 comprised substantially of CH₄) from a separator (38, which receives the expanded exhaust stream 34 directly from the expander 30) coupled to the one of the condensing turbine and the piston (30) to a second compressor (44, driven by drive source 46 and generating compressed vapor stream 48) for one of facilitating cooling at the cooling assembly (heat exchanger 24, in which the low moisture compressed NG stream 21 is pre-cooled to approximately –40° C. by the cold methane vapor) and facilitating cooling at another cooling assembly fluidly coupled to the one of the condensing turbine and the piston (recirculation stage 500 and recirculation path 501) (¶ 0025, 0028, 0031–0033; figs. 1, 2).
In regard to claim 16, Lissianski teaches the method of claim 15 wherein the second compressor (44/46) is provided in a unitary form with the one of the condensing turbine and the piston (30), the multi-phase turbo expander (30) being mechanically coupled through a common shaft (36) and, alternatively, being mechanically coupled with compressor (46) (¶ 0029, 0033; figs. 1, 2).
Claim(s) 1, 8, 12 and 13 are additionally and alternatively rejected under 35 U.S.C. 102(a)(1) as being anticipated by Lockwood et al. (US 2011/0302955 A1).
This rejection is presented in the alternative, to the extent Applicant maintains that a condensing turbine requires a turbine expressly disclosed as forming a condensed phase within the machine itself. Lockwood provides that express disclosure, its invention being characterized in that the second cooling step is performed in at least one expansion turbine, the solid forming inside the turbine (¶ 0012).
In regard to claim 1, Lockwood teaches a cryogenic-based carbon dioxide capture system (low-temperature cryo-condensation purification unit 7, detailed at figs. 1 and 5) comprising:
an exhaust line (the line conveying the flue gases from boiler 1 through filter 103, cooling tower 105 and residual water vapor elimination unit 107) for channeling a gas stream (24/30/32/38/40), the gas stream (24) having an initial mean temperature (of the order of 150° C.) and including carbon dioxide gas (¶ 0002, 0016, 0018, 0071–0077, 0171; figs. 1, 5, 8, 9);
a cooling assembly (exchanger 109) fluidly coupled to the exhaust line to bring a temperature of the stream (40) down to an initial cooling temperature (a temperature close to, but in all events higher than, the temperature at which CO₂ solidifies, situated at around –100° C. for a process fluid containing on the order of 15% CO₂ by volume at a pressure close to atmospheric) between the initial mean temperature and a de-sublimation temperature for the carbon dioxide gas in the stream (¶ 0077; figs. 1, 5); and
one of a condensing turbine (expansion turbine 612, comprising upstream stator part 960 with fixed or variable vanes 950, a rotor part having blades 952 with leading edge 951 and trailing edge 954, and impeller 962) and a piston fluidly coupled to the cooling assembly (109) to condense the carbon dioxide from the stream (42) into a solid form (carbon dioxide snow 62 formed inside the rotor part of the turbine) by work extraction (a near-isentropic expansion with production of work, cooling the fluid to a temperature below the cryo-condensation temperature for CO₂) (¶ 0012, 0111–0113, 0180–0182; figs. 5, 14, 15).
In regard to claim 8, Lockwood teaches the cryogenic-based carbon dioxide capture system of claim 1 further comprising a separator (the separator situated downstream of the rotor part of turbine 612, and vessel 111) coupled to the one of the condensing turbine and the piston (612) to divert solidified carbon dioxide (the solid 62 comprising predominantly CO₂, recovered at the periphery 958 of the flow by the centrifugal effect and tipped into the liquid CO₂ bath 121 for management, transport and local use) from the stream and provide a substantially carbon-free emission (CO₂-lean gas 44, recovered at the center of the flow 959 and containing less than 10% CO₂ by volume and, in one particular embodiment, less than 1% CO₂ by volume, corresponding to a capture level of 90% from a process fluid containing 15% CO₂) for management (¶ 0025, 0078, 0086, 0090, 0095, 0120–0121, 0182; figs. 1, 5, 14, 15).
In regard to claim 12, Lockwood teaches a method of cryogenic-based carbon capture from an exhaust gas stream in a system, the method comprising:
channeling the exhaust gas stream (24/40) with an initial mean temperature to a cooling assembly (exchanger 109) of the system to bring a temperature thereof down to an initial cooling temperature (close to, but higher than, the CO₂ solidification temperature, around –100° C.) between the initial mean temperature and a de-sublimation temperature for the carbon dioxide gas in the stream (¶ 0071–0077; figs. 1, 5); and
solidifying carbon dioxide (carbon dioxide snow 62) from the stream (42) with one of a condensing turbine (expansion turbine 612, the solid forming inside the turbine) and a piston (¶ 0012, 0111–0113; figs. 5, 14, 15).
In regard to claim 13, Lockwood teaches the method of claim 12 further comprising compressing the stream (24) at a compressor (101) in advance of the channeling to the cooling assembly (109), the flue gases being compressed in the compressor (101) upstream of filter (103), cooling tower (105), water vapor elimination unit (107) and exchanger (109) (¶ 0071–0077; fig. 1).
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1 and 12 are additionally and alternatively rejected under 35 U.S.C. 103 as being unpatentable over Lissianski et al. (US 2015/0033792 A1) in view of Lockwood et al. (US 2011/0302955 A1).
This alternative rejection is presented solely to address the contingency that the recitation of a condensing turbine is construed more narrowly than set forth above, so as to require a turbine expressly characterized as condensing the working fluid within the machine.
In regard to claims 1 and 12, Lissianski teaches each limitation as set forth in the § 102 rejection above, including an exhaust line (14/16), a cooling assembly (cooling stage 200 comprising air cooler 29 and heat exchanger 24) bringing the stream (16/21) down to an initial cooling temperature of approximately –40° C. between the initial mean temperature and the de-sublimation temperature for the carbon dioxide gas in the stream, and a multi-phase turbo expander (30/70) fluidly coupled to the cooling assembly (24) that condenses the carbon dioxide from the stream (32) into a solid form by work extraction (¶ 0022–0029, 0040–0045; figs. 1–4).
Assuming arguendo, Lissianski does not explicitly employ the term “condensing turbine” to denominate the multi-phase turbo expander (30).
However, Lockwood teaches a cryogenic carbon dioxide capture method in which the second cooling step is performed in at least one expansion turbine (612), the solid comprising predominantly CO₂ (62) forming inside the turbine (¶ 0012), the turbine performing a near-isentropic expansion with production of work so as to cool the process fluid (42) below the cryo-condensation temperature for CO₂ and to produce carbon dioxide snow within the rotor part (blades 952 between leading edge 951 and trailing edge 954) (¶ 0111–0113, 0180–0182; figs. 5, 14, 15). Lockwood expressly identifies the advantage of employing such a turbine to effect the phase change, namely that a great deal of solid CO₂ can be generated in a very small volume as compared with indirect-exchange systems (¶ 0122).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to configure the expansion device (30) of Lissianski as an expansion turbine within which the condensed and solidified phases are formed, as taught by Lockwood (612; ¶ 0012, 0111–0113), in order to generate a large quantity of solid carbon dioxide within a very small equipment volume as compared with indirect heat-exchange systems (Lockwood ¶ 0122), and thereby to reduce the equipment footprint and capital cost that Lissianski identifies as objectives of its own system (Lissianski ¶ 0002, 0056). Both references are directed to the same field of endeavor – cryogenic separation of carbon dioxide from a gas stream by work-producing expansion – and the modification amounts to the use of a known turbine configuration for its known and expressly stated purpose, yielding no more than predictable results.
Claim(s) 4, 6, 7, 17 and 18 are rejected under 35 U.S.C. 103 as being unpatentable over Lissianski et al. (US 2015/0033792 A1) in view of Reddy et al. (US 2016/0327337 A1).
In regard to claim 4, Lissianski teaches the cryogenic-based carbon dioxide capture system of claim 1 further comprising a compressor (first compressor 22, which may comprise multi-stage compressor 26 with inter-stage cooling) coupled to the exhaust gas line (14/16) for compressing the stream (16/20) in advance of reaching the cooling assembly (29, 24) (¶ 0025–0028, 0036; figs. 1, 2).
Lissianski does not explicitly teach compressing the stream to between about 3 bara and about 10 bara.
However, Reddy teaches a cryogenic CO₂ capture configuration wherein a flue gas (101) is compressed by a blower (BL-101) to generate a pressurized flue gas stream (102) at a pressure of 50–150 psia (approximately 3.45 bara to 10.3 bara), which is then pre-cooled in a first precooler (E-101) in advance of downstream CO₂ desublimation (¶ 0027; figs. 1A, 2A). Reddy therefore establishes that from about 3 bara to about 10 bara is a known and conventional upstream compression range for cryogenic CO₂ capture systems applied to flue gases.
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to operate the compressor (22/26) of Lissianski within the pressure range of about 3 bara to about 10 bara, in view of the teaching of Reddy (BL-101, stream 102; ¶ 0027), in order to provide favorable CO₂ partial pressure conditions for downstream desublimation, to permit reasonable equipment sizing for the heat exchangers (24) and the expansion device (30), and to obtain the energy-efficient operation of cryogenic CO₂ capture systems confirmed by Reddy’s disclosure. One of ordinary skill would have selected a compression pressure within this established range with a reasonable expectation of success in achieving the desired downstream CO₂ capture performance. Furthermore, 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. See MPEP § 2144.05(II).
In regard to claim 6, Lissianski teaches the cryogenic-based carbon dioxide capture system of claim 1 wherein the cooling assembly is a first cooling assembly (air cooler 29), the system further comprising a moisture removal device (12, configured as a molecular sieves bed or other sorbent or solvent based system) and a second cooling assembly (heat exchanger 24) to bring the stream (21) down to a working temperature (approximately –40° C.) between the initial cooling temperature and a de-sublimation temperature for carbon dioxide in the stream in advance of the stream (32) reaching the one of the condensing turbine and the piston (30) (¶ 0023, 0026–0029; figs. 1, 2).
Lissianski does not explicitly teach: (a) that the initial cooling temperature is above 0° C.; (b) a mechanical separator dedicated to water removal positioned between the first and second cooling stages; or (c) a dryer positioned between the first and second cooling stages.
However, Reddy teaches a staged cryogenic CO₂ capture process wherein the pressurized flue gas stream (102) enters a first precooler (E-101) and is cooled to form a stream (103) at a temperature above the freezing point of water, expressly above 0° C.; the stream (103) then enters a dryer (D-101), which removes condensed liquid water as a stream (105) by mechanical separation and which also dries the gas stream, Reddy stating that the dryer (D-101) may be a glycol or other suitable gas dryer and thereby establishing that the unit provides both a mechanical separator function and a drying function; and the dry cooled flue gas (104) thereafter enters a second precooler (E-102) to be cooled to below 0° C. and above the CO₂ desublimation temperature (¶ 0024; figs. 1A, 2A). Reddy’s unit (D-101) thus teaches both the mechanical separator and the dryer of claim 6, positioned between the first and second cooling stages as claimed.
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the system of Lissianski by (1) setting the temperature of the first cooling assembly (29) above 0° C., and (2) positioning a mechanical separator and dryer unit, as taught by Reddy (D-101; ¶ 0024), between the first cooling assembly (29) and the second cooling assembly (24). Staging the cooling process so that the first stage operates above 0° C. allows liquid water to be removed efficiently as a liquid before the gas encounters the colder second stage and the downstream cryogenic equipment. Water that is not removed before the second stage will freeze in the second-stage heat exchangers and downstream equipment, causing fouling, plugging and forced system shutdowns – a concern Lissianski itself identifies in stating that, to avoid icing of the downstream heat exchanger(s), moisture in the NG stream (16) must be reduced in the moisture removal device (12) (¶ 0024). Positioning the drying step between the two cooling stages, as Reddy teaches, exploits the initial cooling to condense water while avoiding ice formation, improves dryer efficiency and reduces equipment size.
In regard to claim 7, the modified combination of Lissianski in view of Reddy teaches the cryogenic-based carbon dioxide capture system of claim 6 wherein the second cooling assembly is a recuperator (heat exchanger 24, which employs the cold CH₄ vapor stream 40 returned by way of recirculation path 501 and second compressor 44 to pre-cool the incoming low moisture compressed NG stream 21, thereby providing recuperative heat exchange) (Lissianski ¶ 0028, 0031–0032, 0039; figs. 1, 2) and the working temperature is between about –80° C. and about –120° C. (Reddy teaching cooling of the dry cooled flue gas 104 in the second precooler E-102 to below 0° C. and above approximately –100° C., more typically above –115° C. at about atmospheric pressure, ¶ 0024; figs. 1A, 2A), a range that overlaps the claimed range. A prima facie case of obviousness exists where the claimed ranges and the prior art ranges overlap. See In re Peterson, 315 F.3d 1325, 1329 (Fed. Cir. 2003); MPEP § 2144.05(I). The combination as modified for claim 6 above establishes operation within this working temperature range in advance of the stream (32) reaching the expander (30).
In regard to claim 17, Lissianski teaches the method of claim 12 including extracting water from the natural gas stream (16) at a moisture removal device (12), which generates a low moisture NG stream (20) (¶ 0023–0026; figs. 1, 2).
Lissianski does not explicitly teach extracting water from the exhaust gas stream at the initial cooling temperature.
However, Reddy teaches extracting water from the pressurized flue gas stream at the initial cooling temperature above 0° C., the dryer (D-101) removing the liquid water stream (105) from the pre-cooled stream (103) at a temperature above the freezing point of water and between the first precooler (E-101) and the second precooler (E-102) (¶ 0024; figs. 1A, 2A).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Lissianski to extract water from the stream at the initial cooling temperature, as taught by Reddy (D-101, stream 105; ¶ 0024), for the same reasons stated in the rejection of claim 6 above: removing water in the liquid phase at a temperature just above 0° C., before the gas is cooled further in the second stage, prevents ice formation in the downstream cryogenic equipment (Lissianski ¶ 0024) and improves dryer efficiency.
In regard to claim 18, the modified combination of Lissianski in view of Reddy teaches the method of claim 17 wherein the cooling assembly is a first cooling assembly (air cooler 29), the method further comprising cooling the stream (21) to a working temperature (approximately –40° C. per Lissianski; below 0° C. and above the CO₂ desublimation temperature per Reddy) between the initial cooling temperature and a de-sublimation temperature for carbon dioxide in the stream at a second cooling assembly (heat exchanger 24; Reddy’s second precooler E-102) in advance of the solidifying of the carbon dioxide at the expander (30) (Lissianski ¶ 0025–0029, 0039; figs. 1, 2; Reddy ¶ 0024; figs. 1A, 2A).
Claims 19 and 20 are rejected under 35 U.S.C. 103 as being unpatentable over Lissianski et al. (US 2015/0033792 A1) in view of Baxter et al. (US 2020/0318900 A1).
In regard to claim 19, Lissianski teaches the method of claim 12 further comprising separating the solidified carbon dioxide from the stream, the expanded exhaust stream (34) being separated at a separator (38) into a vapor stream (40) and an LNG/ice/solid CO₂ slurry stream (42), and the slurry stream (42) being further separated at a liquid/solid separator (50, being a gravity separator, a cyclone, a sintered metal filter or other filter) into an LNG output stream (52) and an output stream (54) comprised substantially of ice/solid CO₂ (¶ 0031, 0034, 0038; figs. 1, 2).
Lissianski does not explicitly teach: (a) liquifying the separated solidified carbon dioxide; or (b) further directing the liquified carbon dioxide to one of a return to the cooling assembly, a routing to another cooling assembly coupled to the one of the condensing turbine and the piston, and a routing to a line for extraction of the carbon dioxide.
However, Baxter teaches a process fluid separation method wherein a solid CO₂ product stream (46) is warmed against a refrigerant (62) in a heat exchanger (18) and pressurized by a pump (20), yielding a liquid CO₂ product stream (54), and wherein the liquid CO₂ stream (54) is thereafter directed across a cooling assembly (heat exchanger 14), where it provides cooling duty for the incoming process fluid stream (40), thereby recovering the refrigeration value of the CO₂ product and improving overall process thermal efficiency (¶ 0025–0027; fig. 3). Baxter further discloses the downstream management and routing options for the resulting liquid CO₂ product, including its withdrawal from the process (¶ 0034–0035).
Therefore, it would have been obvious to a person of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Lissianski by liquifying the separated solid carbon dioxide (54) and directing the liquified carbon dioxide to a cooling assembly of the process, as taught by Baxter (streams 46 and 54, heat exchangers 14 and 18, and pump 20; ¶ 0025–0027), because: (1) both Lissianski and Baxter are directed to the same field of cryogenic separation of carbon dioxide from a gas stream; (2) liquifying and recycling separated solid CO₂ as a cooling medium is a recognized heat-integration technique that recovers the latent and sensible cold content of the CO₂ product, directly improving process energy efficiency; (3) the modification appends Baxter’s downstream CO₂ handling step to Lissianski’s existing solid CO₂ separation step at the separator (50), these being compatible and sequential process steps; and (4) the result is entirely predictable, namely a reduced external refrigeration load and an improved overall system efficiency, as Baxter expressly demonstrates. See MPEP § 2143(I)(A), (G).
In regard to claim 20, the modified combination of Lissianski in view of Baxter teaches the method of claim 19 wherein the directing is powered by a solid pump (pump 20) that is selected from a group consisting of a solid pump that is discrete from the one of the cooling assembly and the other cooling assembly (the pump 20 being a discrete component structurally separate from the heat exchangers 14 and 18, which pressurizes the CO₂ stream and drives it across the heat exchanger 14) and a solid pump that is unitary with the one of the cooling assembly and the other cooling assembly (¶ 0025–0027; fig. 3). The first recited alternative is expressly met by Baxter, and disclosure of one alternative of a Markush group is sufficient. The alternative in which the pump is integrated as a unitary assembly with a cooling assembly presents a packaging and footprint variant that would have been obvious to one of ordinary skill as a straightforward engineering expedient aimed at reducing system complexity, minimizing fluid connections and decreasing installation cost, without any unexpected result. Integrating separate elements into a one-piece construction, where doing so does not change the operation of the device, is a matter of obvious engineering choice. See MPEP § 2144.04(V)(B).
Response to Arguments
Applicant’s arguments with respect to the amended claims have been considered but are moot in view of the new ground(s) of rejection, unless otherwise noted below.
Applicant’s argument (Remarks, p. 7) that the § 112(a) enablement rejection should be withdrawn because the Examiner’s substantive rejections under §§ 102 and 103 demonstrate “apparent full understanding of the claimed subject matter as one skilled in the art.”
In response, the Examiner respectfully disagrees. Comprehension of a claim and enablement of that claim are distinct inquiries governed by distinct statutory provisions. A rejection under 35 U.S.C. 102 or 103 requires the Examiner to determine the broadest reasonable interpretation of the claim and compare it to the prior art; a rejection under 35 U.S.C. 112(a) asks whether the specification teaches a person of ordinary skill how to make and use the full scope of what is claimed without undue experimentation. It is well settled that a claim may simultaneously be unpatentable over the prior art and non-enabled, and the Office is required to examine on both grounds. See MPEP §§ 2103(VI), 2164.04. In the amended claims, the Examiner understands what a piston is does not establish that the specification teaches how to use one to desublimate carbon dioxide from a flue gas stream at less than about –120° C. The Examiner further notes that Applicant has substantially prevailed on this issue. The enablement rejection as applied to the functional language “in a manner facilitating a discouraging of surface accretion within the system” and to the genus “volumetric affecting device” has been withdrawn in view of the Amendment. A new 112a rejection is applied only as to the express “piston” alternative recited in claims 1 and 12, for which the specification supplies a single sentence at ¶ 0019 and nothing further. Where a claim recites alternatives, the specification must enable each alternative. See MPEP §§ 2164.08, 2164.08(b). Deletion of the “piston” alternative would place the claims in condition to overcome this ground of rejection.
Applicant’s argument (Remarks, p. 6-7) that “there is no question that both terms as now employed would be universally understood by someone of skill in the art.”
In response, the Examiner agrees, and applies precisely that universally understood meaning. A “condensing turbine” as understood in the art is a turbomachine in which the expanding working fluid undergoes a phase change to a condensed state. Lissianski’s multi-phase turbo expander 30/70 is expressly such a machine: it is defined as “a radial, axial, or mixed flow turbo-machine through which a gas or gas mixture is expanded to produce work” (¶ 0040), it has a housing 72, a work-extracting rotor 74, a stator/nozzle 76 and blades 80, 82 (¶ 0041; Figs. 3, 4), and “Cooling the gas stream 86 in the multi-phase turbo expander 70 results in formation of a CH₄ vapor, LNG, and one or both of solid CO₂ and liquid CO₂ in the multi-phase turbo expander 70” (¶ 0045). Applicant’s two positions cannot be reconciled: the term cannot be both universally understood in the art and inapplicable to a turbine in which the working fluid demonstrably condenses and desublimates internally.
Applicant’s argument (Remarks, p. 9) that “Neither of these elements are taught or even suggested by Lissianski,” and that “Lissianski is no longer a pertinent reference,” such that each and every element of the claims is not shown under 35 U.S.C. 102.
In response, the Examiner respectfully disagrees. As set forth in the Preliminary Note and in the element-by-element mapping above, Lissianski discloses a condensing turbine on three independent bases: (1) the expander is structurally a turbine – a radial, axial or mixed flow turbo-machine having a housing 72, a rotor 74 that extracts work, a stator or nozzle 76, and stationary and rotor blades 80, 82 (¶ 0040–0041; Figs. 3, 4); (2) condensation of the working fluid occurs inside that turbine, with LNG, liquid CO₂ and solid CO₂ formed within the expander itself as a result of work extraction (¶ 0029, 0045); and (3) the instant specification itself treats “condensing turbine” and “turbo-expander” as alternative names for the same work extraction mechanism 185 (¶ 0014, 0019, 0022), as did now-cancelled claim 3, which recited both as species of a single “dynamic mechanism.” Additionally and alternatively, Lockwood anticipates claims 1, 8, 12 and 13 as set forth above. Lockwood’s invention is expressly characterized by the requirement that the second cooling step “is performed in at least one expansion turbine, said solid forming inside said turbine” (¶ 0012), the turbine 612 producing carbon dioxide snow within the rotor part by a near-isentropic expansion with production of work (¶ 0111–0113; Figs. 5, 14, 15). Even under the narrowest construction Applicant could reasonably advance, a turbine in which the solid forms inside the turbine is a condensing turbine.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a). A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
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/W.M/Examiner, Art Unit 3763
/JOHN F PETTITT, III/Primary Examiner, Art Unit 3763
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