DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim 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 37 and 42 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 written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
Claim 37, recites “the cooled two-phase refrigerant stream has a pressure of at least 68.95 bara”, wherein to the extent claim 37 is construed as referring to the stream formed in step (d) of claim 26 — consistent with the use of the identical, unqualified phrase “the cooled two-phase refrigerant stream” elsewhere in claim 26, e.g., in step (n) — claim 37 is rejected under 35 U.S.C. 112(a) as failing to comply with the written description requirement. On that construction, “the cooled two-phase refrigerant stream” of claim 37 refers to the stream formed by cooling the compressed refrigerant stream of step (c) in the first ambient cooler, i.e., the lowest-pressure two-phase stream in the process, upstream of the second and third compression stages.
The specification as filed discloses a pressure of “at least 1000 PSIA (68.95 bara)” for only one stream in the disclosed process: the two-phase high-pressure refrigerant stream that is introduced into the main/cryogenic heat exchanger after the third compression stage, the third ambient cooler, and recombination with the pumped liquid streams (see original Aspect 11: “the cooled two-phase high pressure refrigerant stream has a pressure of at least 1000 PSIA (68.95 bara)”; ¶ 0031). That stream corresponds to the stream formed in step (l) of claim 26, not the step (d) stream.
The specification's disclosed pressure for the step (d) stream is instead on the order of 10 to 20 bara, the discharge pressure of the first compression stage before any subsequent compression (¶ 0116: compressed “to a pressure typically from 10 to 20 bara,” producing “the resulting cooled two-phase refrigerant stream”). Nothing in the specification supports the step (d) stream — which, by the express structure of claim 26, must undergo two further compression stages in steps (f) through (j) before reaching the high-pressure regime — having a pressure of at least 68.95 bara. Accordingly, on the step (d) construction, the specification does not reasonably convey to a person of ordinary skill in the art that the inventor had possession of a process in which that stream, specifically, is at a pressure of at least 68.95 bara. This rejection does not apply to the alternative construction, addressed in the rejection of claim 37 under 35 U.S.C. 112(b) below, in which “the cooled two-phase refrigerant stream” refers to the step (a) stream; however, that alternative construction does not resolve the indefiniteness of claim 37, for the reasons given above.
Claim 42 depends from claim 41 and separately recites “wherein the cooled two-phase refrigerant stream has a pressure of at least 68.95 bara.” To the extent claim 42 is construed on the same basis as claim 37, the specification does not describe the step (d) stream — as opposed to the stream formed in step (l) — as having a pressure of at least 68.95 bara, and claim 42 is rejected under 35 U.S.C. 112(a) as failing to comply with the written description requirement for the same reasons given above with respect to claim 37.
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 26, 28-34 and 37-43 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 26 has been amended to delete “high pressure” from step (a), such that step (a) now recites cooling and condensing the hydrocarbon stream and “a cooled two-phase refrigerant stream” in the main heat exchanger. This is the identical name given to a different stream introduced later in the same claim: step (d) separately recites cooling the compressed refrigerant stream of step (c) in a first ambient cooler “to form a cooled two-phase refrigerant stream.” By the process logic of claim 26, these are two distinct streams at two distinct points in the process, the step (a) stream is the fully-compressed, high-pressure stream entering the main heat exchanger together with the hydrocarbon stream, while the step (d) stream is the lower-pressure stream immediately downstream of only the first of three compression stages. Yet claim 26 now gives both streams the same unqualified name, “a cooled two-phase refrigerant stream.” Because of this, a person of ordinary skill in the art cannot determine with reasonable certainty which stream is referenced by “the cooled two-phase refrigerant stream” in step (n), which recites combining the expanded cooled stream of step (m) with “the cooled two-phase refrigerant stream” to form “the combined cooled two-phase refrigerant stream” of step (e). Therefore, claim 26 is indefinite for this reason.
Claim 30 has been amended to delete the reference to “in step (l)” from its recitation that “all of the refrigerant flows through the hydraulic turbine.” This amendment overcomes the antecedent-basis rejection of claim 30 set forth in the Non-Final Office Action mailed April 22, 2026, which was based on claim 30's prior reference to a hydraulic turbine “in step (l)” notwithstanding that step (l) recites only a cooling operation and the hydraulic turbine is recited solely in step (b); that rejection is hereby withdrawn. Claim 30 nonetheless remains rejected under 35 U.S.C. 112(b) because it depends from indefinite claim 26 and does not resolve the indefiniteness identified above.
Claim 37 recites “wherein the cooled two-phase refrigerant stream has a pressure of at least 68.95 bara.” Because claim 26 now uses this identical, unqualified phrase for two different streams — the stream entering the main heat exchanger in step (a) and the lower-pressure stream formed in step (d) — for the reasons given in the rejection of claim 26 above, claim 37 lacks a single, clear antecedent for “the cooled two-phase refrigerant stream” and is indefinite for this additional reason. If “the cooled two-phase refrigerant stream” of claim 37 is construed consistently with its use elsewhere in claim 26 (i.e., in step (n), where it refers to the step (d) stream), then, as explained in the rejection of claim 37 under 35 U.S.C. 112(a) above, the recited pressure of at least 68.95 bara is facially inconsistent with the position of that stream in the process, since that stream is formed after only a single compression stage and remains subject to two further compression stages. If, instead, “the cooled two-phase refrigerant stream” of claim 37 is construed as referring to the step (a) stream, no such inconsistency arises, but the underlying ambiguity as to which stream is meant remains unresolved on the face of the claim.
Claim 42 depends from claim 41 and separately recites “wherein the cooled two-phase refrigerant stream has a pressure of at least 68.95 bara,” the same limitation recited in claim 37, and is indefinite for the same reasons given above with respect to claim 37.
Solely for purposes of compact prosecution and to reach the prior art rejection under 35 U.S.C. 103 below, claims 37 and 42 are given their broadest reasonable interpretation, construing “the cooled two-phase refrigerant stream” as referring to the stream corresponding to step (l) of claim 26 (the cooled two-phase compressed stream entering the main heat exchanger), consistent with the specification's disclosure of a pressure of at least 68.95 bara for a stream at that position in the process (original Aspect 11). This interpretation is adopted only for purposes of applying prior art and does not constitute a finding that the claims are, in fact, definite.
Claims 28, 29, 31-34 and 38-41 and 43 are rejected under 35 U.S.C. 112(b) for being dependent upon a rejected claim.
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.
Claim(s) 26 and 28-34 are rejected under 35 U.S.C. 103 as being unpatentable over Brostow et al. (US 2016/0327335 A1) in view of Jung et al. (US 2014/0053600 A1) and further in view of Hodges et al. (US 9562718 B2).
In regard to claim 26, Brostow teaches a method for liquefying a hydrocarbon stream using a mixed refrigerant (Abstract; fig. 7), the method comprising:
(a) cooling and condensing the hydrocarbon stream (700) and a cooled two-phase refrigerant stream (781) in a main heat exchanger (703) against an expanded refrigerant stream (the refrigerant stream after valve 756) to form a liquefied hydrocarbon stream (704), a condensed refrigerant stream (the refrigerant stream before the J-T valve 756), and a vaporized refrigerant stream (710) (fig. 7; ¶¶ 0080, 0096); Note: FIG. 7 elements corresponds to the elements of fig. 1 and 2. The elements have the same function and structure as fig. 1 and 2, because of that the discussion of such elements is not be repeated (see ¶ 0080).
(b) expanding (via J-T valve 756) the condensed refrigerant stream (the refrigerant stream before the J-T valve 756) to form the expanded refrigerant stream (refrigerant stream after valve 756) (see fig. 7),
(c) compressing the vaporized refrigerant stream (710) in a first compression stage (via the 1st stage of the compressor 712) to a first pressure to form a low pressure compressed refrigerant stream (714) (see fig. 7);
(d) cooling the low pressure compressed refrigerant stream (714) in a first ambient cooler (716) to form a cooled two-phase refrigerant stream (718) (see fig. 7; ¶ 0104);
(e) separating, via 760, a combined cooled two-phase refrigerant stream (streams 718 and the stream after expansion valve 752) into a first cooled vapor stream (762) and a first cooled liquid stream (764) (fig. 7);
(f) compressing the first cooled vapor stream (762) in a second compression stage (the second stage of compressor 712) to a second pressure to form a compressed stream (725) (fig. 7);
(g) pumping, via 790, the first cooled liquid stream (764) to a third pressure to form a pumped first cooled liquid stream (fig. 7);
(h) cooling the compressed stream (725) in a second ambient cooler (726) to form a cooled compressed stream (728) (fig. 7);
(i) separating (via separator 730) the cooled medium pressure compressed stream (728) into a second cooled vapor stream (732) and a second cooled liquid stream (766) (see fig. 7);
(k) combining the pumped first cooled liquid stream (stream coming out of pump 790) with the second cooled vapor stream (732) to form a combined two-phase high-pressure compressed stream (781) (see fig. 7; ¶ 0113);
(m) expanding the second cooled liquid stream (766) through an expansion valve (752) to form an expanded cooled stream (fig. 7); and
(n) combining, inside separator 760, the expanded cooled stream (stream after the valve 752) with the cooled two-phase refrigerant stream (718) to form the combined cooled two-phase refrigerant stream (fig. 7). This mapping treats step (a)’s “cooled two-phase refrigerant stream” as corresponding to stream 781 (the fully-compressed stream entering the main heat exchanger) and step (d)’s identically-named stream as corresponding to stream 718, consistent with Brostow’s disclosure; as discussed in the rejection of claim 26 under 35 U.S.C. 112(b) above, claim 26 itself does not clearly distinguish between these two identically-named streams.
Brostow does not explicitly teach (j) compressing the second cooled vapor stream in a third compression stage to the third pressure to form a two-phase compressed stream, or (l) cooling the combined two-phase compressed stream in a third ambient cooler to form the cooled two-phase compressed stream.
Jung, however, teaches a boil-off gas liquefaction system in which BOG supplied to a reliquefaction apparatus (20) is cooled and reliquefied by a refrigerant, and specifically teaches compressing a second cooled vapor stream (the vapor exiting separator 22b) in a compression stage (23b) to form a two-phase compressed stream, combining that stream with a pumped first cooled liquid stream (from pump 26a, liquid from separator 22a), and cooling the combined stream in a cooler (24b) (fig. 3b; ¶¶ 0089-0090).
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 hydrocarbon liquefaction process of Brostow by incorporating a compressor and cooler to compress the second cooled vapor stream to a third pressure to form a two-phase compressed stream, and to combine that stream with the pumped first cooled liquid stream prior to cooling the combined stream, in view of the teachings of Jung, for the purpose of raising the refrigerant discharge pressure and increasing the amount of liquid formed in the high-pressure circuit, thereby improving the coefficient of performance of the refrigerant cycle.
Brostow further teaches expanding the condensed refrigerant stream through a Joule-Thomson expansion valve (756) to form the expanded refrigerant stream (fig. 7; ¶¶ 0100, 0122), but does not explicitly teach performing at least a portion of that expansion using a hydraulic turbine.
Hodges, however, teaches that in an LNG liquefaction process using a mixed refrigerant, a sub-cooled light refrigerant stream (100) removed from the cold end of the main heat exchanger (12) is expanded through a second expansion device (102) — explicitly described as, for example, a hydraulic turbine — to produce a reduced-pressure refrigerant stream (104) (col. 9, ll. 10-35; fig. 2), which is then introduced into the shell side of the main heat exchanger at its cold end to evaporate and provide refrigeration duty (col. 9, ll. 44-55).
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 expansion valve of Brostow with a hydraulic turbine as taught by Hodges, because Brostow and Hodges operate in the same technical field — LNG liquefaction using a mixed refrigerant — and both expand a sub-cooled refrigerant stream from the main heat exchanger to provide shell-side refrigeration. A person of ordinary skill in the art would have been motivated to substitute the known Joule-Thomson valve of Brostow with the hydraulic turbine of Hodges to recover mechanical work from the expansion step and thereby reduce the net power consumption of the liquefaction process, a well-recognized objective in the field, representing a routine substitution of one known expansion device for another to achieve predictable energy savings and presenting no unexpected challenges.
Brostow, as modified above, teaches a second and a third cooler, but does not explicitly teach that these coolers are ambient coolers. Official notice is taken that ambient-air cooling is a well-known, effective, and efficient method of reducing the temperature of compressed fluids. A person of ordinary skill in the art would have found it obvious to modify the refrigerant compressor after-coolers of the modified Brostow process with ambient-based after-coolers to enhance heat rejection capability and increase energy efficiency, particularly in warmer environments, yielding the predictable results of lower discharge temperatures and reduced compressor duty, and representing nothing more than a combination of known elements to improve efficiency, well within the capability of an ordinary artisan.
In regard to claim 28, the modified Brostow process teaches the method of claim 26, wherein Brostow teaches that in SMR compression circuits the refrigerant is cooled “back to close-to-ambient temperature” in the intercooler and aftercooler (¶¶ 0097, 0104), but does not explicitly teach that the second compression stage operates at a temperature of approximately 96.8° F. The specific value of approximately 96.8° F (approximately 36° C) is a temperature achievable with standard cooling water at typical process conditions and represents an optimized near-ambient interstage temperature. One of ordinary skill in the art would have found it obvious to design the compression circuit of the modified Brostow process to operate the second stage at this temperature by routine optimization of the ambient cooler, as the specific temperature falls within the ordinary range of near-ambient cooling achievable with standard industrial cooling-water systems. Selection of this specific operating temperature represents a routine engineering expedient well within the skill of the art.
In regard to claim 29, the modified Brostow process teaches the method of claim 26, wherein the expanded refrigerant stream (the stream after expansion valve 756) provides the sole refrigeration duty for step (a) (see Brostow fig. 7; see also the rejection of claim 26 above).
In regard to claim 30, the modified Brostow process teaches the method of claim 26, wherein the flow of the refrigerant in steps (a) through (n) defines a closed loop refrigeration cycle and all of the refrigerant flows through the hydraulic turbine substituted into step (b), as discussed in the rejection of claim 26 above (see Brostow fig. 7).
In regard to claim 31, the modified Brostow process teaches the method of claim 26, wherein the main heat exchanger (703) comprises a warm bundle (703a) and a cold bundle (703c) contained within separate shells (see Brostow fig. 7; ¶¶ 0122-0124).
In regard to claim 32, the modified Brostow process teaches the method of claim 31, wherein the main heat exchanger (703) additionally comprises a middle bundle (703b) located between the warm bundle (703a) and the cold bundle (703c) (see Brostow fig. 7).
In regard to claim 33, the modified Brostow process teaches the method of claim 26, wherein the hydrocarbon stream (700) comprises natural gas (see Brostow ¶¶ 0083, 0095).
In regard to claim 34, the modified Brostow process teaches the method of claim 26, wherein the main heat exchanger (703) comprises a warm end (703a) and a cold end (703c), and the expanded refrigerant stream (the stream after expansion valve 756) is introduced into the main heat exchanger at the cold end (703c) (see fig. 7; ¶ 0095).
Claim(s) 37-43 are rejected under 35 U.S.C. 103 as being unpatentable over Brostow, Jung and Hodges as applied to claim 26 above, and further in view of Cardella et al. (11,340,012 B2).
In regard to claim 37, the modified Brostow teaches the method of claim 26, the modified Brostow teaches as best understood in light of the rejection of claim 37 under 35 U.S.C. 112 above (construing the limitation as directed to the stream corresponding to step (l) of claim 26, i.e., the cooled two-phase compressed stream entering the main heat exchanger), but does not explicitly teach he cooled two-phase refrigerant stream has a pressure of at least 68.95 bara. However, it would have been obvious to a person of ordinary skill in the art to design the modified Brostow process such that this stream has a pressure of at least 68.95 bara. Cardella discloses pumping an analogous liquid mixed-refrigerant stream to a high pressure “particularly in the range of 30 bar(a) and 70 bar(a)” before combining it with a compressed vapor refrigerant stream to form the corresponding two-phase high-pressure mixed-refrigerant stream entering the precooling cold-box (col. 12, ll. 60-67), a range that directly encompasses 68.95 bara and confirms that this pressure is an art-recognized, conventional operating point for the analogous final high-pressure stream in a multi-stage mixed-refrigerant cycle of this general type, rather than a newly-discovered value. The discharge pressure of the final, combined high-pressure stream in a multi-stage mixed-refrigerant liquefaction cycle is a result-effective variable, i.e., a variable recognized in the art as affecting a desired result: Jung expressly teaches that raising the discharge pressure of an analogous compressed refrigerant/BOG stream from a conventional low pressure of about 4 to 8 bara to a higher pressure of about 12 to 45 bara “considerably reduce[s]” the energy consumed in the downstream reliquefaction duty (Jung ¶¶ 0021, 0037), such that determining a workable or optimum discharge pressure for a stream of this kind is no more than routine optimization of a recognized result-effective variable. See MPEP § 2144.05(II)(A). A person of ordinary skill in the art seeking to maximize the refrigeration performance of the modified Brostow process would accordingly have been motivated to raise the final compression discharge pressure toward, and to, at least 68.95 bara. A person of ordinary skill would have had a reasonable expectation of success in doing so because Cardella confirms that pressures at or above this level are readily achievable for an analogous stream using conventional compression and cooling equipment.
In regard to claim 38, the modified Brostow teaches the method of claim 26, the modified Brostow does not explicitly teach the two-phase compressed stream has a pressure between 40 and 70 bara. However, 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 third compression stage of the modified Brostow process — which produces the two-phase compressed stream of step (j) and the combined two-phase compressed stream of step (k) — within a discharge pressure range of 40 to 70 bara. Brostow's own Example 1 discloses compressing the refrigerant to “635 psia” (approximately 43.8 bar) in an analogous compression stage (¶ 0121), and Cardella discloses pumping an analogous liquid mixed-refrigerant stream to a high pressure “particularly in the range of 30 bar(a) and 70 bar(a)” before combining it with a compressed vapor refrigerant stream to form a two-phase high-pressure mixed-refrigerant stream (col. 12, ll. 60-67), each falling within or squarely matching the claimed 40 to 70 bara range and confirming that this range is a conventional, art-recognized operating window for the final compression stage of a multi-stage mixed-refrigerant cycle of this general type. The discharge pressure of this stage is a result-effective variable, as Jung expressly teaches that raising the discharge pressure of an analogous compression stage improves liquid recovery and reduces specific power consumption of the downstream liquefaction duty, up to a point of diminishing returns above roughly 45 bara (Jung ¶¶ 0021, 0037, 0069-0073). A person of ordinary skill in the art seeking to maximize refrigeration efficiency while avoiding the added compressor duty and capital cost of operating at still higher pressure would accordingly have been motivated to target the claimed 40-70 bara range for the final compression stage, using no more than routine optimization of this recognized result-effective variable. See MPEP § 2144.05(II)(A). A person of ordinary skill would have had a reasonable expectation of success in doing so, since Brostow's own working example and Cardella both confirm that pressures in this range are readily achievable using conventional compression and cooling equipment in mixed-refrigerant compression trains of the same general type.
In regard to claim 39, the modified Brostow teaches the method of claim 26, the modified Brostow does not explicitly teach the compressed stream has a pressure between 25 and 30 bara. However, it would have been obvious to a person of ordinary skill in the art to operate the second compression stage of the modified Brostow process — which produces the compressed stream of step (f) — within a discharge pressure range of 25 to 30 bara. Cardella discloses compressing an analogous vapor refrigerant stream to a high pressure “particularly in the range of 25 bar(a) and 60 bar(a)” (col. 12, ll. 63-67), a range that directly encompasses the claimed 25 to 30 bara and confirms that this is a conventional, art-recognized intermediate-stage discharge pressure in multi-stage mixed-refrigerant compression cycles. As with the third compression stage addressed in the rejection of claim 38 above, discharge pressure at this stage is a result-effective variable that Jung expressly ties to liquid recovery and specific power consumption (Jung ¶¶ 0021, 0037, 0069-0073), such that a person of ordinary skill in the art would have been motivated to select and optimize the second-stage discharge pressure within this range in order to balance the liquid-formation and refrigeration-efficiency benefits of a higher intermediate pressure against the added compressor duty of operating at still higher pressure at that stage, using no more than routine experimentation. See MPEP § 2144.05(II)(A). A person of ordinary skill would have had a reasonable expectation of success in doing so given cardella's confirmation that this pressure range is readily attainable using conventional equipment in an analogous multi-stage mixed-refrigerant process.
In regard to claim 40, the modified Brostow teaches the method of claim 26, the modified Brostow does not explicitly teach the compressed refrigerant stream has a pressure from 10 to 20 bara. However, it would have been obvious to a person of ordinary skill in the art to operate the first compression stage of the modified Brostow process — which produces the compressed refrigerant stream of step (c) — within a discharge pressure range of 10 to 20 bara. Brostow's own Example 1 discloses compressing the refrigerant “from 54 psia (3.7 bar) to 262 psia (18.1 bar)” in an analogous first compression stage (¶ 0121), and Cardella discloses that the discharge pressure of an analogous first-stage compressed refrigerant stream is “particularly in the range of 10 bar(a) to 25 bar(a)” (col. 12, ll. 56-59), each falling within or overlapping the claimed 10 to 20 bara range and confirming that this range is not merely theoretical but an actual, working discharge pressure already used for directly analogous first-stage compression steps in the art. Discharge pressure at this stage is likewise a result-effective variable that Jung expressly ties to downstream refrigeration/reliquefaction energy consumption (Jung ¶¶ 0021, 0037, 0069-0073), such that a person of ordinary skill in the art would have been motivated to select a first-stage discharge pressure within this range that establishes an efficient starting point for the higher-pressure stages that follow it in the overall multi-stage compression sequence, using no more than routine optimization. A person of ordinary skill would have had a reasonable expectation of success in doing so because both Brostow's disclosed value and Cardella's disclosed range confirm that pressures in this range are already in productive, working use in directly analogous first-stage compression steps using conventional equipment.
In regard to claim 41, the modified Brostow teaches the method of claim 26, the modified Brostow does not explicitly teach the pressure ranges of claims 38, 39, and 40 in combination (the two-phase compressed stream has a pressure between 40 and 70 bara; the compressed stream has a pressure between 25 and 30 bara; and the compressed refrigerant stream has a pressure from 10 to 20 bara). However, it would have been obvious to a person of ordinary skill in the art to select and optimize all three compression-stage discharge pressures of the modified Brostow process together, within the ranges of 40 to 70 bara, 25 to 30 bara, and 10 to 20 bara, respectively, for the reasons given in the rejections of claims 38, 39, and 40 above. A person of ordinary skill in the art would have been motivated to optimize each stage's discharge pressure in combination, rather than in isolation, because the three compression stages of a multi-stage mixed-refrigerant cycle are interdependent — the discharge pressure selected for each upstream stage sets the suction conditions for the stage that follows — such that Jung's teaching of raising discharge pressure to improve reliquefaction efficiency (Jung ¶¶ 0021, 0037, 0069-0073) would naturally have led a person of ordinary skill to consider and optimize the pressure profile of the compression train as a whole. A person of ordinary skill would have had a reasonable expectation of success in arriving at a combination of pressures within all three claimed ranges simultaneously, particularly because, as shown above, each individual range is independently corroborated by an actual, working operating pressure disclosed in Brostow's Example 1 and/or Cardella (col. 12, ll. 56-67: first-stage discharge “10 bar(a) to 25 bar(a)”, vapor-stream discharge “25 bar(a) and 60 bar(a)”, liquid-stream discharge “30 bar(a) and 70 bar(a)”), rather than resting on speculation as to whether such pressures are attainable in combination.
In regard to claim 42, the modified Brostow teaches the method of claim 41, the modified Brostow does not explicitly teach the cooled two-phase refrigerant stream has a pressure of at least 68.95 bara. However, which depends from claim 41 and additionally recites that the cooled two-phase refrigerant stream has a pressure of at least 68.95 bara, the modified Brostow process, optimized as set forth in the rejections of claims 38, 39, 40, and 41 above, further renders this additional limitation obvious for the same reasons given in the rejection of claim 37 above: Cardella's disclosed range of 30 bar(a) to 70 bar(a) for an analogous high-pressure stream directly encompasses 68.95 bara, discharge pressure of the corresponding high-pressure stream is a result-effective variable that Jung ties to improved liquid recovery and reduced specific power consumption (Jung ¶¶ 0021, 0037, 0069-0073), a person of ordinary skill would have been motivated to raise this pressure to at least 68.95 bara for the same reasons discussed with respect to claim 37, and a person of ordinary skill would have had a reasonable expectation of success in doing so for the same reasons discussed with respect to claim 37.
In regard to claim 43, the modified Brostow teaches the method of claim 26, the modified Brostow does not explicitly teach a pressure of the two-phase compressed stream is greater than a pressure of the compressed stream; and the pressure of the compressed stream is greater than a pressure of the compressed refrigerant stream. However, the modified Brostow process, optimized as set forth in the rejections of claims 38, 39, and 40 above, inherently produces successive compression-stage discharge pressures that increase from the first stage, to the second stage, to the third stage, consistent with Brostow's own low-, medium-, and high-pressure staging (¶¶ 0091, 0097, 0104-0113) and with Cardella's own ascending disclosed ranges across successive compression stages (col. 12, ll. 56-67: approximately 10-25 bara, then 25-60 bara, then 30-70 bara). A person of ordinary skill in the art would have been motivated to arrive at this ascending pressure profile, rather than merely finding it as an incidental byproduct, because Jung's teaching of raising discharge pressure at each successive compression stage to progressively improve liquid recovery and reduce specific power consumption (Jung ¶¶ 0021, 0037, 0069-0073) is only realized by an ascending, stage-by-stage pressure sequence of exactly the kind recited in claim 43; a monotonically increasing discharge-pressure profile across the first, second, and third compression stages is thus the expected and intended mechanism by which the motivating benefit is achieved, rather than an unexpected or fortuitous result. A person of ordinary skill would have had a reasonable expectation of success in arriving at such a profile given that both Brostow and Cardella already disclose ascending, multi-stage compression sequences of this general kind. It would accordingly have been obvious to a person of ordinary skill in the art that the pressure of the two-phase compressed stream is greater than the pressure of the compressed stream, and that the pressure of the compressed stream is greater than the pressure of the compressed refrigerant stream, as recited in the claim.
Response to Arguments
Applicant's arguments filed 07/22/2026 have been fully considered but they are not persuasive.
Applicant argues (Remark page 8-9) that the combination of Brostow with Jung, to arrive at the third compression stage and third ambient cooler of steps (j) and (l), and the combination of Brostow with Hodges, to arrive at the hydraulic turbine of step (b), is impermissibly “gleaned only from Applicant's disclosure” and is therefore based on improper hindsight.
In response, the allegation is not persuasive. Applicant's argument that the examiner's conclusion of obviousness is based upon improper hindsight reasoning, it must be recognized that any judgment on obviousness is in a sense necessarily a reconstruction based upon hindsight reasoning. But so long as it takes into account only knowledge which was within the level of ordinary skill at the time the claimed invention was made, and does not include knowledge gleaned only from the applicant's disclosure, such a reconstruction is proper. See In re McLaughlin, 443 F.2d 1392, 170 USPQ 209 (CCPA 1971). In this case, Jung's own disclosure independently provides the reason to add a compression stage and cooler of the kind recited: Jung explains that compressing BOG to a higher, “medium” pressure of 12 to 45 bara, rather than the conventional low pressure of 4 to 8 bara, considerably reduces the energy required for reliquefaction (Jung ¶¶ 0021, 0037, 0068-0073), and Jung's Figure 3b embodiment specifically discloses compressing a second cooled vapor stream and combining it with a pumped liquid stream ahead of a cooler, exactly as relied upon in the rejection (Jung ¶¶ 0089-0090). This rationale — raising mixed-refrigerant discharge pressure to improve reliquefaction and refrigeration performance — is Jung's own stated rationale, not one gleaned from applicant's specification. Hodges likewise independently discloses substituting a hydraulic turbine for a Joule-Thomson valve to expand a sub-cooled refrigerant stream from the main heat exchanger, for the purpose of recovering mechanical work and reducing net power consumption (Hodges, col. 9, ll. 10-55), which is a rationale articulated by Hodges itself. Because each combined teaching carries its own, independently-stated motivation, the rejection is not based on impermissible hindsight reconstruction.
Applicant further argues (Remark page 9-10) that the data of original Figure 5 establish unexpected results that rebut the prima facie case of obviousness, specifically that the actual efficiency improvement of the claimed process over the prior-art PRICO® process of Figure 4 (13.2% for the Figure 1 embodiment; 15.6% for the Figure 3 embodiment corresponding to claim 26) exceeds the sum of the individually-measured benefits of adding a hydraulic turbine alone (6.0%) and adding a third compression stage, second intercooler, and second pump alone (5.2%), i.e., 13.2% actual versus 11.2% expected.
In response, this showing has been fully considered but does not overcome the rejection, for the following reasons. First, a showing of unexpected results must compare the claimed invention against the closest prior art — here, the Brostow, Jung, and Hodges combination actually applied in the rejection, rather than against an unrelated construct. See MPEP § 716.02(e). Applicant's comparison is instead made against the PRICO® process of specification Figure 4, a different, two-stage-compression, single-intercooler prior-art cycle that is not the reference relied upon in the rejection and that is materially less similar to the claimed process than Brostow, which already discloses multi-stage compression with liquid-forming intercoolers and a mixing column, i.e., most of the structural framework of claim 26. A comparison against Figure 4 does not establish that the claimed process behaves unexpectedly relative to the closer Brostow, Jung, and Hodges combination. Second, the showing is not commensurate in scope with the claims. The data of Figure 5 reflect a single fixed production rate, fixed ambient temperature, fixed pressure drops, fixed exchanger approach temperatures, fixed compressor efficiencies, and an optimized mixed-refrigerant composition for that one data set (¶ 0131). Claim 26 is not limited to any particular production rate, ambient temperature, or refrigerant composition, and claims 37-43 recite only broad pressure ranges. A showing of unexpected results limited to a single, optimized operating point does not establish unexpected results across the full scope of claim 26. See In re Clemens, 622 F.2d 1029 (CCPA 1980); In re Peterson, 315 F.3d 1325 (Fed. Cir. 2003). Third, even accepting applicant's own framing, the “unexpected” component of the result is a 2.0 percentage-point difference between an expected 11.2% benefit and an observed 13.2% benefit for the Figure 1 embodiment, a difference in degree rather than in kind. Because both the added compression stage and the hydraulic turbine act on the same mixed-refrigerant discharge pressure and the same refrigeration cycle, some degree of positive interaction between them would reasonably have been expected by a person of ordinary skill, rather than being unpredictable. A mere difference in degree, without more, is generally insufficient to establish unexpected results. Fourth, no data of record decompose the benefit for the Figure 3 embodiment corresponding to claim 26 into individually-attributable and combined components; the only quantitative support offered for that embodiment is the single comparison that “a comparison of the prior art process of FIG. 4 (column 1) and the process of FIG. 3 (column 5) shows a 15.6% benefit.” There is accordingly no evidentiary basis of record establishing that the claim 26 embodiment specifically achieves a synergistic, as opposed to simply cumulative, result at all.
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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to WEBESHET MENGESHA whose telephone number is (571)270-1793. The examiner can normally be reached Mon-Thurs 7-4, alternate Fridays, EST. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Frantz Jules can be reached at 571-272-6681. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000.
/W.M/Examiner, Art Unit 3763
/FRANTZ F JULES/Supervisory Patent Examiner, Art Unit 3763
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