DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Amendment
The amendments filed March 04, 2026, have been entered. Accordingly, claims 1-18 are currently pending.
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 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.
Claims 1, 3, 7-8, and 16-18 are rejected under 35 U.S.C. 103 as being unpatentable over Applicant Admitted Prior Art Fig. 2 (CN 105890281 A) in view of Zielinski et al. (US20190310013A1) and Kaart (US 20110277498 A1).
In re Claim 1, AAPA teaches a process for purifying and liquefying natural gas (AAPA Fig. 2 and AAPA [0038]) the process comprising the steps of: precooling a natural gas flow (Fig. 2: 13) in a cryogenic exchanger (1) obtaining a pre-cooled natural gas flow (See Fig. 2: bottom stream leaving 1) and pretreating the precooled natural gas flow inside a pretreatment unit (4; See [0038]: separator for heavy hydrocarbons 4 to remove the heavy hydrocarbons) obtaining a purified flow of natural gas (Fig. 2 stream leaving top of 4).
AAPA does not explicitly teach heat recovering inside the cryogenic exchanger obtaining a higher temperature flow, compressing said higher temperature flow by a first compressor obtaining a first compressed recirculation flow cooling said first compressed recirculation flow in a first natural gas cooler, obtaining a compressed and cooled flow, separating from said compressed and cooled flow of a first portion which is subjected to the steps of: a further cooling liquefying and possibly subcooling inside said cryogenic exchanger obtaining a flow of liquefied natural gas, b expanding said flow of liquefied natural gas by of a first valve obtaining a flow of liquefied natural gas at a lower pressure, separating from said compressed and cooled flow a recirculation flow portion of the natural gas which is subjected to the steps of: a cooling inside said cryogenic exchange obtaining a first cooled recirculation flow of the natural gas, b expanding said first cooled recirculation flow of the natural gas in an expander obtaining a second recirculation flow of the natural gas. and c subjecting said second recirculation flow of the natural gas to of heat recovery inside said cryogenic exchanger obtaining a third natural gas recirculation flow at a higher temperature which is reunited with said higher temperature flow to form an overall recirculation flow to be subjected to o step wherein one or more of the cooling steps 1, 6a, 7a are carried out by a flow of nitrogen that circulates inside a closed nitrogen refrigeration cycle.
However, Zielinski teaches heat recovering inside the cryogenic exchanger (4) obtaining a higher temperature flow ([0078]: stream is heated),
compressing said higher temperature flow by a first compressor (6b,12) obtaining a first compressed recirculation flow (F-2),
cooling said first compressed recirculation flow in a first natural gas cooler (G24) obtaining a compressed and cooled flow (F-P),
a first portion (F-G), which is subjected to the steps of:
6a) further cooling, liquefying and possibly sub-cooling, inside said cryogenic exchanger (4) obtaining a flow of liquefied natural gas ([0083]: cooling the light NGL stream F-G may be performed directly in the main cryogenic heat exchanger 4),
6b) expanding said flow of liquefied natural gas by of a first valve (28) obtaining a flow of liquefied natural gas at a lower pressure (See [0028]),
separating from said compressed and cooled flow a recirculation flow portion of the natural gas , which is subjected to the steps of:
7a) cooling, inside said cryogenic exchanger (4), obtaining a first cooled recirculation flow of the natural gas (stream leaving 4 entering 8a) ,
7b) expanding said first cooled recirculation flow of the natural gas (stream entering 8a) in an expander (8a) obtaining a second recirculation flow of the natural gas (stream exiting 8a), and
7c) subjecting said second recirculation flow of the natural gas to of heat recovery inside said cryogenic exchanger obtaining a third natural gas recirculation flow at a higher temperature (See Fig. 1 and [0096]: turbine stream is warmed in 4, then compressed in 8 to stream F-3), which is reunited with said higher temperature flow to form an overall recirculation flow ([0110]) to be subjected to
step 4), wherein one or more of the cooling steps 1), 6a), 7a) are carried out by a flow of nitrogen that circulates inside a closed nitrogen refrigeration cycle (14, 10a, 10b).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed for process for purifying and liquefying natural gas of AAPA to include a nitrogen cycle with multiple compressors driven by electricity which uses ambient air as the heat sink based on the teaching of Zielinski since it has been shown that combining prior art elements to yield predictable results is obvious whereby one having ordinary skill in the art would consider it obvious to use a known process of liquefying natural gas such as that taught by Zielinski in order to form a first natural gas stream contributing by heat exchange firstly to pre-cooling a main natural gas stream flowing in counter-current through the main cryogenic heat exchanger, and secondly to cool an initial refrigerant gas stream flowing in counter-current through the main cryogenic heat exchanger (Zielinski [0024]).
Modified AAPA does not explicitly teach separating from said compressed and cooled flow of a first portion.
However, Kaart (Fig. 1) teaches separating ([0071]: using divider 18) from said compressed and cooled flow (20) of a first portion (20 b).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, to have taken the teachings of Modified AAPA and to have modified them by separating from said compressed and cooled flow of a first portion, in order to maintain minimum flow during start-up and recirculation (See Kaart [0072-0073]), without yielding unpredictable results.
In re Claim 3, Modified AAPA teaches wherein step 4) is carried out on the higher temperature flow (F-1 leaving heat exchanger 4), with which the third natural gas recirculation flow (F-3) is reunited, forming a second overall recirculation flow (stream entering 6b), which is then compressed in the first compressor (6b), obtaining a first compressed recirculation flow (F-2).
In re Claim 8, Modified AAPA teaches wherein said closed nitrogen refrigeration cycle (Zielinski 14, 10a, 10b) comprises the steps of:
A) subjecting a low-pressure nitrogen recirculation flow (flow into 10; See Zielinski [0065-0066]) to a compression in a first compressor of the closed nitrogen refrigeration cycle (10b; See [0106]),
obtaining a first high-pressure nitrogen recirculation flow (stream leaving 10b), and to a successive step of cooling in a first cooler of the closed nitrogen refrigeration cycle (34; [0106]: cooled by a refrigerant gas cooler 34 a),
obtaining a first cooled high-pressure nitrogen flow (See Fig. 2 and [0106]:compressed stream prior to being cooled by 34),
B) subjecting said first cooled high-pressure nitrogen flow (G-0) to a step of heat exchange in the cryogenic exchanger (4) obtaining a further cooled high-pressure nitrogen flow,
C) subjecting said further cooled high-pressure nitrogen flow (5) to a step of expansion (10a) in an expander of the closed nitrogen refrigeration cycle (10 a),
obtaining a low- pressure nitrogen recirculation flow (G-1),
and) subjecting said low-pressure nitrogen recirculation flow to a step of heat recovery in the cryogenic exchange (4)|([0105]: the flow of this first refrigerant gas stream G-1 through the main cryogenic heat exchanger exchanges heat so as to cool),
obtaining the low-pressure nitrogen recirculation flow to be subjected to step A) (See Step A supra).
In re Claim 7, Modified AAPA teaches wherein, the first portion separated in step 6) (Kaart 20b; See also [0071]) has a capacity of about 10-40% of the capacity of said compressed and cooled flow (Kaart [0072]: capacity is between 0-100% of cooled and compressed stream 20).
In re Claim 16, Modified AAPA teaches wherein a flow of removed compounds is obtained from step 2) (AAPA [0038]: for heavy hydrocarbons 4 to remove the heavy hydrocarbons).
In re Claim 17, Modified AAPA teaches the limitations because Zielinski teaches a plant (Fig. 1) for purifying and liquefying natural gas, the plant comprising:
a natural gas circuit (2) inside which flows of natural gas circulate ([0061]: circulates natural gas),
the flows of natural gas being cooled flows ([0067]: cooled flows using refrigerant),
the natural gas circuit comprising:
a pre-treatment unit (16 corresponding to AAPA 4) for pre-treating said natural gas1,
a section for compressing (12), cooling (cooled by 4) and expanding (28) said natural gas,
a point for recovering liquefied natural gas (GNL) for storage or introduction thereof into a convenient distribution network2;
a nitrogen circuit (14, 10a, 10b) inside which several flows of nitrogen circulate,
the flows of nitrogen being cooled or heated flows ([0101-0104]: cooled flows of nitrogen),
the nitrogen circuit comprising:
a tank of nitrogen (source for nitrogen implicitly disclosed by any nitrogen refrigeration cycle),
a section for compressing (10a and 14), cooling (cooled by 4) and expanding (10a) the nitrogen; and
a cryogenic exchanger (4) comprising: a section for cooling, liquefying and sub-cooling (these processes necessarily occur in cryogenic heat exchanger 4) the natural gas.
In re Claim 18, Zielinski discloses wherein said cryogenic exchanger (Zielinski 4) is configured to allow thermal exchanges (Zielinski [0083]) between one or more of said flows of natural gas (Zielinski [0065]) with one or more of said flows of nitrogen (flows through Zielinski 14, 10a, 10b).
Claim 2 is/are rejected under 35 U.S.C. 103 as being unpatentable over Applicant Admitted Prior Art Fig. 2 (CN 105890281 A) as modified by Zielinski et al. (US20190310013A1) and Kaart (US 20110277498 A1), further in view of Roberts et al. (US 20070157662 A1).
In re Claim 2, Modified AAPA teaches does not explicitly teach, wherein, after step 1) and/or after step 2) the pre-cooled natural gas flow (See AAPA Fig. 2: bottom stream leaving 1) and/or said purified flow of natural gas are expanded, obtaining an expanded pre-cooled flow and/or a purified and further expanded flow, respectively.
However, Roberts teaches wherein, after step 1) the pre-cooled natural gas flow (7) is expanded (Fig. 1: expanded by valve 9; See [0041]), obtaining an expanded pre-cooled flow (10).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention, to have taken the teachings of Modified AAPA and to have modified them by having wherein, after step 1) of Modified AAPA the pre-cooled natural gas flow of modified AAPA is expanded (Fig. 1: expanded by valve 9; See [0041]), obtaining an expanded pre-cooled flow (10) as taught by Roberts, in order to lower the pressure of the natural gas fluid and autorefrigerate the natural gas to a lower temperature (See Roberts[0041]), without yielding unpredictable results.
Response to Arguments
The Remarks of March 4, 2026 have been fully considered but are not persuasive for the reasons below.
Applicant argues
On Page 8-10 of the Remarks, that the examiner has not shown that claims 1 are obvious over AAPA (Ju) in view of Zielinski and Kaart because there is allegedly no basis in the prior art for cold, post-pre-cooling removal of acidic compounds required by the claims. Furthermore, there is no basis for the pre-treatment step being performed on the pre-cooled natural gas flow followed by heat recovery and recompression. Applicant appears to suggest that one of ordinary skill in the art would not recognize from the teaching of Ju that the pre-cooled natural gas flow followed by heat recovery and recompression. It is further suggested by Applicant that neither reference provides the requisite guidance for removal of acidic compounds. This is not persuasive.
First, in response to applicant's argument that the references fail to show certain features of applicant's invention, it is noted that the features upon which applicant relies (i.e., maintaining a superheat degree) are not recited in the rejected claim(s). Although the claims are interpreted in light of the specification, limitations from the specification are not read into the claims.3 As currently amended, the recitation in claim 1 requires
A process for purifying and liquefying natural gas, the process comprising the steps of:
1) pre-cooling a natural gas flow in a cryogenic exchanger obtaining a pre-cooled natural gas flow,
2) pre-treating the pre-cooled natural gas flow inside a pre-treatment unit obtaining a purified flow of natural gas,
3) heat recovering inside the cryogenic exchanger obtaining a higher temperature flow, 4) compressing said higher temperature flow by a first compressor obtaining a first compressed recirculation flow,
but does not necessarily require cold, post-pre-cooling removal of acidic compounds. Nonetheless, assuming arguendo, one of ordinary skill in the art would recognize that Ju at least suggests pre-treating the pre-cooled natural gas flow inside a pre-treatment unit obtaining a purified flow of natural gas. As shown in the APPA figure 24, the pre-treating the pre-cooled natural gas flow can be construed as purifying the natural gas flow.
Second, the Examiner disagrees with Applicant’s characterization of modified Ju, the current combination of prior art references teaches and suggests the pre-cooled natural gas flow followed by heat recovery and recompression (see Claim 1 recitation supra). Thus, applicant's arguments that the prior art does not suggest the claim language of 3) heat recovering inside the cryogenic exchanger obtaining a higher temperature flow, 4) compressing said higher temperature flow by a first compressor obtaining a first compressed recirculation flow, is considered unpersuasive. In response to applicant's arguments against the references individually, one cannot show nonobviousness by attacking references individually where the rejections are based on combinations of references. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981); In re Merck & Co., 800 F.2d 1091, 231 USPQ 375 (Fed. Cir. 1986). Ju teaches the process of the pre-treated and pre-cooled natural gas flow and Zielinski/Kaart thereafter teach the heat recovery and recompression steps. The combination Ju/Zielinski/Kaart teaches the pre-cooled natural gas flow followed by heat recovery and recompression. Therefore, the rejection is maintained.
Since Ju/Zielinski/Kaart teach or suggest all the limitations of Claim 1, applicant’s remaining arguments are moot as the rejection of Claim 1 is maintained and additional arguments are not presented in regards to Claims 2-3, 7-8, and 16-18.
Allowable Subject Matter
Claims 5-6 , 13 and 15 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
Reasons for Allowance
The following is a statement of reasons for the indication of allowable subject matter:
In re claim 5, there are no prior art teachings that would otherwise supplement or substitute the teachings of Applicant Admitted Prior art (AAPA) to arrive at the claimed invention. The prior art fails to teach the arrangement of a first high-pressure flow is separated from the first compressed recirculation flow obtained from step 4). Although other prior art teachings, such as Zielinski provide support for compressing said higher temperature flow by a first compressor (6b,12) obtaining a first compressed recirculation flow (F-2), , said teachings fail to provide support for a first high-pressure flow is used, which is separated from the first compressed recirculation flow obtained from step 4).
Likewise, in re claim 13, there are no prior art teachings that would otherwise supplement or substitute the teachings of Applicant Admitted Prior art (AAPA) to arrive at the claimed invention. The prior art fails to teach the arrangement of [the] flow of liquefied natural gas at a lower pressure obtained from step 6b) is used in step 2). Although other prior art teachings, such as Zielinski provide support for expanding [the] flow of liquefied natural gas by of a first valve (28) obtaining a flow of liquefied natural gas at a lower pressure (See [0028]), said teachings fail to provide support for said flow of liquefied natural gas at a lower pressure obtained from step 6b) is used in step 2).
Moreover, although one of ordinary skill in the art could consider relying on an “obvious to try” rationale5 for changing separating the first compressed recirculation flow to arrive at the claimed invention, the reliance on said rationale is admonished6 by the fact that what would be obvious is to vary all possible parameters or try each of numerous possible choices (e.g. choosing where to join or use the recirculation flow in the process) until one possibly arrived at a successful result, since the prior art does not give any explicit indication of which parameters are critical, nor any direction as to which of many possible choices is likely to be successful.
Likewise, although one of ordinary skill in the art could consider relying on an “obvious to try” rationale7 for changing which portion of natural gas flow to use in a pretreatment step to arrive at the claimed invention, the reliance on said rationale is admonished8 by the fact that what would be obvious is to vary all possible parameters or try each of numerous possible choices (e.g. choosing a portion before or after expansion, or compression or cooling) until one possibly arrived at a successful result, since the prior art does not give any explicit indication of which parameters are critical, nor any direction as to which of many possible choices is likely to be successful.
It should also be noted that the intended purpose and operating principles of AAPA require the specific arrangement of a process for purifying and liquefying natural gas as disclosed and described therein. One of ordinary skill in the art would recognize that any modifications to AAPA to arrive at the claimed invention would be based on improper hindsight, and would render AAPA inoperable for its intended purpose. Assuming arguendo, rearranging and/or replacing the steps for the process of purifying and liquefying natural gas of AAPA would change the principles of operation thereof, since it would require completely redesigning the process of purifying and liquefying natural gas. For instance, rearranging and/or reconfiguring the process of purifying and liquefying natural gas would consequently require completely redesigning the steps that are required to achieve natural gas liquefaction and purification, most likely resulting in unexpected and/or unintended results, which is evidence against a prima facie case of obviousness. Thus, a preponderance of evidence supports the allowability of claims 5, 6, 13 and 15.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to IBRAHIM M ADENIJI whose telephone number is (571)272-5939. The examiner can normally be reached 8:00-5:00 PM.
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Jianying Atkisson can be reached at 571-270-7740. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/IBRAHIM A. MICHAEL ADENIJI/Examiner, Art Unit 3763
/JOEL M ATTEY/Primary Examiner, Art Unit 3763
1 The recitation of " for pre-treating said natural gas," recited in the claim has been considered a recitation of intended use. The prior art structure above is capable of performing as intended. It has been held that the recitation with respect to the manner in which a claimed apparatus is intended to be employed does not differentiate the claimed apparatus from a prior art apparatus satisfying the claimed structural limitation. (MPEP 2114).
2 The recitation of "for storage or introduction thereof into a convenient distribution network," recited in the claim has been considered a recitation of intended use. The prior art structure above is capable of performing as intended. It has been held that the recitation with respect to the manner in which a claimed apparatus is intended to be employed does not differentiate the claimed apparatus from a prior art apparatus satisfying the claimed structural limitation. (MPEP 2114).
3 See In re Van Geuns, 988 F.2d 1181, 26 USPQ2d 1057 (Fed. Cir. 1993).
4 Ju Fig. 1
5 See MPEP § 2143 (I) (E).
6 Id., at § 2145 (X) (B).
7 See MPEP § 2143 (I) (E).
8 Id., at § 2145 (X) (B).
Prosecution Insights