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 .
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 2/17/2026 has been entered.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 4 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 4 recites “the at least one heat upstream heat exchanger” which lacks antecedent basis in the claims. For the purpose of examination, this limitation is understood to be “the at least one upstream heat exchanger”.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 1, 4, 9-10, 13, 15-17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Teo (US Patent No. 8534094), hereinafter referred to as Teo and further in view of Mak et al (US PG Pub 20200370824), hereinafter referred as Mak.
With respect to claim 1, Teo teaches a method to extract ethane from a stream of initial natural gas (Figure 2), comprising:
cooling a stream of initial natural gas in at least one first upstream heat exchanger, to form a stream of cooled natural gas (hydrocarbon feed stream 10, cooled in heat exchangers 110, 112, 114 Column 6, lines 12-17),
separating the stream of cooled natural gas into a liquid flow and a gas flow (cooled gas is passed into separator 17 to produce bottom liquid stream 18 and overhead gaseous stream 19, Column 6, lines 19-24),
expanding of the liquid flow and introduction at least one stream coming from the liquid flow at a first level into a methane and C2+ hydrocarbons separation column (bottom liquid 18 is expanded in valve 13 and is then passed to an NGL recovery column, Column 6, lines 19-23),
forming a turbine feed stream from the gas flow (overhead gas flow 19 passes to NGL expander 15, Column 6, lines 21-22, which can be seen in the figure to be a turbine),
expanding the turbine feed stream in a dynamic expansion turbine to form an expanded stream (stream 19 is expanded in turbine 15 which as it is part of a turbo-expander would be a dynamic expansion turbine) and introducing the stream coming from the dynamic expansion turbine into the separation column at a second level (mixed-phase stream 16 formed of expanded 19 is passed to NGL recovery column 14 above the liquid stream, Column 6, lines 22-24),
introducing a bottom stream rich in C2+ hydrocarbons recovered from the separation column into a fractionation column and recovering a flow of ethane from the fractionation column (C2+ enriched bottom stream can be passed to a fractionation column to provide an ethane stream, Column 5, lines 6-20),
recovering and compressing at least part of a head stream coming from the separation column to for a stream of compressed purified natural gas (overhead 31 from 14 is compressed in 32, Column 6, lines 30-35),
liquefying the stream of compressed purified natural gas in a liquefier to form a stream of a pressurized liquefied natural gas (compressed methane stream is ultimately sent to main cooling stage 42 to provide a liquefied stream 50, Column 5, lines 25-39),
flash expanding of the stream of pressurized liquefied natural gas (50 is expanded in 52, Column 5, lines 39-44), recovering expanded liquefied natural gas in a storage (the expanded natural gas 80 is passed to storage, Column 5, lines 49-51),
recovering at least one flow of flash gas coming from the flash expanding of the stream of pressurized liquefied natural gas (end-flash stream of gas 70, Column 5, lines 54-56 is recovered from 62),
compressing the at least one flash gas to form a compressed gas (70 is compressed in 72, Column 5, lines 54-56),
separating the flow of compressed flash gas into a fuel stream and a recycle stream (compressed flash stream is divided into fuel gas 90a and recycle fraction 90b, Column 5, lines 61-63).
Teo does not teach at least partial cooling and expansion of the recycle stream to form a cooled and expanded recycle stream followed by introducing the cooled and expanded recycle stream at a head stage of the separation column, wherein introducing the cooled and expanded recycle stream at a head stage of the separation column is carried out at a first level starting from the top of the separation column.
Mak teaches that a recycle stream (21) from an overhead natural gas stream (9) is cooled in the same heat exchanger (53, paragraph 49) used for cooling the feed and the stream is then expanded (54) before being sent back as a top reflux line (paragraphs 53-54).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Mak instead of recycling the flash gas stream back to the overhead of the fractionation column to have recycled the stream back through the heat exchangers (110 and 114, which would be the equivalent to the feed exchanger of Mak) and then expanded the stream and fed it to the top of the column (14) as a reflux stream since it has been shown that combined prior art elements to yield predictable results is obvious whereby recycling the stream as reflux instead of into the compressed stream would provide what would be common knowledge in the art of increasing the separation in the column separation column through the use of reflux which would increase the recovery of methane in the overhead. As the stream is a reflux is to the top of the column this can be considered a first level from the top.
With respect to claim 4, Teo as modified teaches comprising introducing the recycle stream in the first heat upstream exchanger of the at least one upstream heat exchanger and cooling the recycle stream by heat exchange in the first heat exchanger with the head stream coming from the separation column (as modified, the recycle stream is passed through the first heat exchanger 110, which is against the head stream 31).
With respect to claim 9, Teo as modified does not teach removing a recirculation stream form the stream of compressed purified natural gas upstream of the liquefaction unit, the recirculation stream being cooled expanded and introduced into the separation column.
Mak teaches that multiple reflux streams can be provided to a separation column (25, 23, paragraphs 129-130) and that one of those reflux streams can be a separated overhead compressed natural gas stream (21) upstream of liquefaction formed from the column (from stream 9) that is recycled back through the heat exchanger where it is cooled and used as reflux in the column (Paragraphs 127-130).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Mak to have provided a second reflux stream to the column of Teo as modified formed of cooling and expanding a portion of the compressed overhead prior to sending the compressed overhead to the liquefaction plant since it has been shown that combining prior art elements to yield predictable results is obvious whereby providing a second reflux stream would provide the predictable result that would be recognized as common knowledge in the art of increasing the reflux to the column and thus increase the separation of the lower boiling components from the higher boiling components which would allow for better recovery of an overhead stream with less or no C2+ hydrocarbons when desired.
With respect to claim 10, Teo as modified teaches wherein flash expanding the stream of pressurized liquefied natural gas and recovering the expanded liquefied natural gas in a storage further comprises expanding the stream of pressurized liquefied natural gas in an dynamic or static expander, followed by introducing an expanded expanding stream of pressurized liquefied natural gas into a flash drum to be separated into the expanded liquefied natural gas introduced into storage and the at least one flow of flash gas (pressurized LNG 50 is expanded in valve 52 and separated in end flash vessel 62, Column 5, lines 39-46, which as it is providing the expansion, it is either static of dynamic).
With respect to claim 13, Teo as modified teaches wherein compressing the head stream coming from the separation column is carried out in at least one first compressor coupled to the to the dynamic expansion turbine (first compression in 32 is coupled to expander 15) and then in a compression machine comprising successively a second compressor (after 32 the first compressed stream is compressed in first compressor, Column 6, lines 36-41) a cooler for the gas compressed in the second compressor (26, Column 6, line 42), and a third compressor (the compressor 24 can be more than one compressor, Column 6, lines 39, which means there can be a second and third compressor) to form the stream of compressed purified natural gas (the stream passing from 26 is the compressed purified natural gas).
With respect to claim 15, Teo as modified teaches forming the turbine feed stream which is sent to the dynamic expansion turbine without separation from an entire gas flow coming from the separation of the stream of cooled natural gas (the entirety of the stream of gas 19 from 17 passes to 15 as seen in the figure).
With respect to claim 16, Teo teaches an ethane extraction installation to extract ethane from a stream of initial natural gas (Figure 2), comprising:
at least one first upstream heat exchanger configured to cool a stream of initial natural gas to form a stream of cooled natural gas (hydrocarbon feed stream 10, cooled in heat exchangers 110, 112, 114m Column 6, lines 12-17),
a separator to separate the stream of cooled natural gas into a liquid flow and a gas flow (cooled gas is passed into separator 17 to produce bottom liquid stream 18 and overhead gaseous stream 19, Column 6, lines 19-24),
a liquid flow expander (bottom liquid 18 is expanded in valve 13 and is then passed to an NGL recovery column, Column 6, lines 19-23),
a methane and C2 hydrocarbons separation column and an inlet to introduce at least one stream coming from the expanded liquid flow into the separation column at a first level ((bottom liquid 18 is expanded in valve 13 and is then passed to an NGL recovery column, Column 6, lines 19-23),
a dynamic expansion turbine configured to expand a turbine feed stream formed form the gas flow, configured to form an expanded stream and an inlet to introduce the expanded stream from the dynamic expansion turbine into the separation column at a second level (gas stream 19 is expanded in turbine 15 which as it is part of a turbo-expander would be a dynamic expansion turbine, mixed-phase stream 16 formed of expanded 19 is passed to NGL recovery column 14 above the liquid stream, Column 6, lines 22-24),
a fractional column, an inlet to introduce a bottom stream in C2+ hydrocarbons coming from the separation column into the fractionation column and an outlet to recover a flow of ethane from the fractionation column (C2+ enriched bottom stream can be passed to a fractionation column which would be via an inlet to provide an ethane stream, Column 5, lines 6-20 which would be recovered via an outlet),
an outlet to recover at least a part of a head stream coming from the separation column and a compressor to compress the at least part of a head stream coming from the separation column, to form a compressed purified natural gas (overhead 31 from 14 which would be via an outlet is compressed in 32, Column 6, lines 30-35),
a liquefier configured to liquefy the stream of compressed purified natural a\gas to form a stream of pressurized liquefied natural gas (compressed methane stream is ultimately sent to main cooling stage 42 to provide a liquefied stream 50, Column 5, lines 25-39),
a flash expander for expansion of the stream of pressurized liquefied natural gas to form a flash expanded liquefied natural gas and a storage to recover the flash expanded liquefied natural gas (50 is expanded in 52, Column 5, lines 39-44 and the expanded natural gas 80 is passed to storage, Column 5, lines 49-51),
an outlet to recover at least one flow of flash gas from the flash expander (outlet from 62 recovers end-flash gas stream 70, Column 5, lines 54-56),
a compressor for compression of the at least one flow of flash gas (70 is compressed in 72, Column 5, lines 54-56),
a separator of the flow of compressed flash gas into a fuel stream and a recycle stream (compressed flash stream is divided by a stream splitter 91 into fuel gas 90a and recycle fraction 90b, Column 5, lines 61-63).
Teo does not teach a cooler/expander to cool at least partially expand the recycle stream and form a cooled and expanded recycle stream, and to introduce the cooled and expanded recycle stream at a head stage of the separation column, at a first level starting from the top of the separation column.
Mak teaches that a recycle stream (21) from an overhead natural gas stream (9) is cooled in the same heat exchanger (53, paragraph 49) used for cooling the feed and the stream is then expanded in a valve (54) before being sent back as a top reflux line (paragraphs 53-54).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Mak instead of recycling the flash gas stream back to the overhead of the fractionation column to have recycled the stream back through the heat exchangers (110 and 114, which would be the equivalent to the feed exchanger of Mak) and then expanded in a valve the stream and fed it to the top of the column (14) as a reflux stream since it has been shown that combined prior art elements to yield predictable results is obvious whereby recycling the stream as reflux instead of into the compressed stream would provide what would be common knowledge in the art of increasing the separation in the column separation column through the use of reflux which would increase the recovery of methane in the overhead. One of the two heat exchanger would be the cooler and the valve would be the expander and flowing the stream to the top of the column would result in it being at a first level starting from the top of the separation column.
With respect to claim 17, Mak as modified teaches wherein the at least one upstream heat exchanger includes a first upstream heat exchanger and a second upstream heat exchanger, wherein cooling the recycle stream includes flowing the recycle stream through both of the first upstream heat exchanger and the second upstream heat exchanger (110 and 114 are both upstream heat exchangers, and the recycle stream as modified flows through both).
Claim(s) 2 is/are rejected under 35 U.S.C. 103 as being unpatentable over Teo/Mak and further in view of Kaart et al. (US PG Pub 20110239701), hereinafter referred to as Kaart.
With respect to claim 2, Teo as modified does not teach does not teach wherein a concentration of methane of the recycle stream is greater than 90 mol%. Teo teaches that the overhead stream from the column is more than 90% methane and nitrogen but is not specific as to the concentration separated that forms the recycle and fuel gas streams.
Kaart teaches that the amount of nitrogen acceptable in a fuel gas stream is based on what is tolerated by how the fuel gas stream is used (paragraph 48). As such the concentration of the fuel gas stream (which would be the same as the concentration of the recycle stream as they are just split from the same stream) is a result effective variable which is optimized based on the usage of the fuel gas stream. Further, it appears that one of ordinary skill in the art would have had a reasonable expectation of success in modify Teo to have the concentration within the claimed range, as it only involves adjusting the concentration of a component disclosed to require adjustment (the concentration of nitrogen, and thus methane in the overhead). Therefore, it would have been obvious to one having ordinary skill in the art at the time of the invention to have operated Teo such that the separated stream (90 and respective streams 90a/90b which would all have the same concentration) that is in part used to form the recycle stream would have a concentration of more than 90% methane as a matter of routine optimization since it has been held that “where the general conditions of a claim are disclosed in the prior art, it is not inventive to discover the optimum or workable ranges by routine experimentation." In re Aller, 220 F.2d 454, 456, 105 USPQ 233, 235 (CCPA 1955).
With respect to claim 18, Teo teaches a method to extract ethane from a stream of initial natural gas (Figure 2), comprising:
providing a stream of initial natural gas to an ethane extraction unit to produce at least one ethane rich flow and natural gas head stream via separation column (gas stream 10 is passed via heat exchangers into NGL recovery system 12 which separates the stream into a C2+ enriched bottom stream and an 31 overhead stream which is methane enriched, Column 6, lines 12-35, which a C2+ stream would be an ethane rich flow and a the methane enriched gas would be a natural gas head stream),
providing the head stream to a liquefaction unit to liquify the natural gas head stream to produce a liquefied natural gas (compressed methane stream formed from stream 31 is ultimately sent to main cooling stage 42 to provide a liquefied stream 50, Column 5, lines 25-39),
providing the liquefied natural gas to a flash storage unit having therein a flash drum thereby separating the liquefied natural gas into a stream of expanded liquefied natural gas and a flow of flash gas (stream 50 is passed via expander 52 into end flash vessel 62 which liquefied hydrocarbon product stream and end gaseous stream 70, Column 5, lines 39-54),
compressing the at least a portion of the flow of flash gas to form a compressed gas;- downstream of the flash drum, separating the flow of compressed flash gas into a fuel stream and a recycle stream rich in methane (70 is compresed in 72, Column 5, lines 54-56).
Teo does not teach at least partial cooling and expanding of the recycle stream to form a cooled and expanded recycle stream, followed by introducing the cooled and expanded recycle stream at a head stage of the separation column, wherein introducing the cooled and expanded recycle stream at a head stage of the separation column is carried out at a first level starting from the top of the separation column.
Mak teaches that a recycle stream (21) from an overhead natural gas stream (9) is cooled in the same heat exchanger (53, paragraph 49) used for cooling the feed and the stream is then expanded (54) before being sent back as a top reflux line (paragraphs 53-54).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Mak instead of recycling the flash gas stream back to the overhead of the fractionation column to have recycled the stream back through the heat exchangers (110 and 114, which would be the equivalent to the feed exchanger of Mak) and then expanded the stream and fed it to the top of the column (14) as a reflux stream since it has been shown that combined prior art elements to yield predictable results is obvious whereby recycling the stream as reflux instead of into the compressed stream would provide what would be common knowledge in the art of increasing the separation in the column separation column through the use of reflux which would increase the recovery of methane in the overhead. As the stream is a reflux is to the top of the column this can be considered a first level from the top.
Claim(s) 5-6 is/are rejected under 35 U.S.C. 103 as being unpatentable over Teo/Mak and further in view of Paradowski (US Patent No. 6578379), hereinafter referred to as Paradowksi and further in view of Gahier et al. (US PG Pub 20140290307)
With respect to claim 5, Teo does not teach comprising separating the gas flow into the turbine stream introduced into the dynamic expansion turbine and into a reflux stream introduced into the separation column at a lower level than a level of introduction of the recycle stream, after cooling the reflux stream in a second upstream heat exchanger of the at least one upstream heat exchanger and expansion of the reflux stream,
Paradowski (Figure 1) teaches that after separation of the feed stream into a vapor stream and a liquid stream (4/3) the vapor stream can then be split into two stream, a turbine stream (45) and another stream (9) which is cooled in the main heat exchanger (which can be seen to be the coldest part) before being recycled and expanded (27) and is sent as a reflux stream below the top reflux (Column 4, lines 49-54). This reflux is lower than reflux formed by a recycle stream (6).
Therefore, it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Paradowski to have separated a portion of the gas stream used as the turbine stream upstream of the turbine, cooled it in a heat exchanger (at least heat exchanger 114 as it is the colder heat exchanger) of Teo as modified and then after passing it through a valve used it as reflux below the top reflux (reflux by the recycle stream) since it has been shown that combining prior element to yield predictable results is obvious whereby providing a second reflux would provide the predictable result that would be recognized as common knowledge in the art of increasing the reflux to the column and thus increase the separation of the lower boiling components from the higher boiling components which would allow for better recovery of an overhead stream with less or no C2+ hydrocarbons when desired.
Teo as modified does not teach that the valve the reflux stream passes through is for static expansion. It should be noted that while it is referred to in Paradowksi as a flow-controlled valve, one of ordinary skill in the art would recognize that it is likely causing expansion of the stream.
Gahier teaches that for introducing a reflux stream to a column a static expansion valve can be used (paragraph 119).
Therefore, it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Gahier to have provided a static expansion valve as the valve of Teo as modified which feeds the reflux stream to the separation column since it has been shown that combining prior art elements to yield predictable results is obvious whereby providing the valve as a static expansion valve would provide the predictable result that would be recognized as common knowledge in the art of being able to bring the reflux stream to the desired pressure while also providing additional predictable cooling to ensure the stream is at the right condition for reflux.
With respect to claim 6, Teo as modified teaches wherein cooling the stream includes flowing the recycle stream through the second upstream heat exchanger (as modified the recycle stream is cooled in both heat exchangers 110 and 114, which is the second heat exchanger).
Claim(s) 7 is/are rejected under 35 U.S.C. 103 as being unpatentable over Teo/Mak and further in Gahier.
With respect to claim 7, Teo as modified wherein expansion of the recycle stream includes flowing the flow of the recycle stream through an expansion valve (as modified the recycle stream passes through an expansion valve).
Gahier teaches that for introducing a reflux stream to a column a static expansion valve can be used (paragraph 119).
Therefore, it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Gahier to have provided a static expansion valve as the expansion valve of Teo as modified which feeds the reflux stream to the separation column since it has been shown that combining prior art elements to yield predictable results is obvious whereby providing the valve as a static expansion valve would provide the predictable result that would be recognized as common knowledge in the art of being able to bring the reflux stream to the desired pressure while also providing predictable cooling to ensure the stream is at the right condition for reflux.
Claim(s) 8, 11-12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Teo/Mak and further in Wilkinson et al. (US PG Pub 20100031700), hereinafter referred to as Wilkinson.
With respect to claim 8, Teo as modified does not teach placing at least part of the compressed purified head natural gas in heat exchanger with the flow of flash gas in a downstream heat exchanger.
Wilkinson teaches that as part of the cooling process for turning the overhead from a column (17) into LNG (40a), that the flash gas (41) can be used to provide cooling in a heat exchanger (51 and 18) (Figures 1, Paragraphs 19-20).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Wilkinson provided a heat exchanger through which the flash gas of Teo as modified is used to provide cooling since it has been shown that combining prior art elements to yield predictable results is obvious whereby utilizing the flash gas stream as a refrigerant stream would provide the predictable result that would be common knowledge in the art of reducing the amount of external cooling necessary to liquefy the pressurized natural gas stream.
With respect to claim 11, Teo as modified does not teach comprising forming the at least one flash gas in storage when the expanded liquefied natural gas is introduced into storage.
Wilkinson teaches that instead of passing a LNG stream after expansion to a flash drum, the stream can be sent to an expansion valve (55) and then sent directly to storage (56) when there is a desired higher amount of LNG flash vapor desired when higher plant fuel consumption happens (paragraph 31).
Therefore, it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Wilkinson to have instead of passing the expanded liquefied natural gas stream to a flash drum (62) to have passed it directly to storage and recovered the flash gas stream when a higher amount of flash gas is desired for plant fuel consumption.
With respect to claim 12, Teo as modified does not teach comprising directly introducing the stream of pressurized liquefied natural gas into the storage without flowing through a flash drum.
Wilkinson teaches that instead of passing a LNG stream after expansion to a flash drum, the stream can be sent to an expansion valve (55) and then sent directly to storage (56) when there is a desired higher amount of LNG flash vapor desired when higher plant fuel consumption happens (paragraph 31).
Therefore, it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of Wilkinson to have instead of passing the expanded liquefied natural gas stream to a flash drum (62) to have passed it directly to storage and recovered the flash gas stream when a higher amount of flash gas is desired for plant fuel consumption.
Claim(s) 14 is/are rejected under 35 U.S.C. 103 as being unpatentable over Teo/Mak and further in Mak (US PG Pub 20170051970), hereinafter referred to as John.
With respect to claim 14, Teo as modified does not teach comprising cooling and partially condensing a head flow coming from the fractionation column to form a cooled and at least partially condensed head flow and then introducing the cooled and at least partially condensed head flow into a drum, recovering the flow of ethane at the head of the drum, the bottom of the head drum being introduce as reflux into the fractionation column.
John teaches a deethanizer (59, paragraph which is a fractionation column) with cooling and partially condensing a head flow coming from the fractionation column to form a cooled and at least partially condensed head flow (overhead stream from the column 29 is cooled in a heat exchanger 70 to form a partially condensed stream 30, paragraph 34) and then introducing the cooled and at least partially condensed head flow into a drum (the two phase stream is provided into a reflux drum), recovering the flow of ethane at the head of the drum (overhead from the stream is recovered as an ethane product, 32), the bottom of the head drum being introduce as reflux into the deethanizer column (the bottom stream 31 from the drum is recycled as reflux to the deethanizer) (paragraph 34).
Therefore it would have been obvious to a person having ordinary skill in the art at the time the invention was filed to have based on the teaching of John to have in Teo provided the fractionation column such that the overhead stream is cooled and partially condensed and send to a drum and separated into a flow of ethane at the head of the drum with the bottom stream being reintroduced as reflux into the fractionation column since it has been shown that combining prior art elements to yield predictable results is obvious whereby providing the column with this configuration would provide what would be common knowledge in the art of producing a desired ethane stream from the fractionation column while using reflux to increase the separation of ethane from any C3+ hydrocarbons present.
Response to Arguments
Applicant's arguments filed 2/17/2026 have been fully considered but they are not persuasive. They are accompanied by a declaration also filed 2/17/2026.
Applicant argues, pages 7-8 that “Teo is trying to optimize the power installed in the liquefaction unit” which correspond to the statements in declaration, paragraphs 5, 7-8 and regarding Mak “it is also well understood by those in the industry, and skilled in the relevant art, that the reflux stream coming from the lean gas should be minimized” which corresponds to the statements in the declaration, paragraph 10 and that “the inventors have found, and what is disclosed in the present invention, is using the advantage provided by an end flash system in combination with a recycled lean gas reflux stream” result in resolving “the conflict between Teo and Mak, by changing the composition of the end flash gas so as to be able to counterintuitively use the overhead lean gas as a reflux stream while still applying a ‘Deep Flash’ end flash system”. This is not persuasive.
Applicant’s arguments and declarations do not provide any factual evidence that such configurations would not be considered obvious to combine. Although an affidavit or declaration which states only conclusions may have some probative value, such an affidavit or declaration may have little weight when considered in light of all the evidence of record in the application. In re Brandstadter, 484 F.2d 1395, 179 USPQ 286 (CCPA 1973). Applicant is only considering Mak and Teo individually and not what may result from their combination and further, no portions of Mak or Teo have been specifically pointed to that support either applicants’ arguments or declaration. Teo provides no teaching of using the alleged “shorter loop, so as not to impact the equipment by the flow turning around” and Mak provides no teaching in regards to a lean gas booster compressor or desiring to minimize the reflux stream coming from the lean gas as argued or declared. As such, while these arguments and declarations are considered, it does not change what one having ordinary skill in the art would consider obvious when considering the prior art. In response to applicant's argument that there is conflict between Teo and Mak, the test for obviousness is not whether the features of a secondary reference may be bodily incorporated into the structure of the primary reference; nor is it that the claimed invention must be expressly suggested in any one or all of the references. Rather, the test is what the combined teachings of the references would have suggested to those of ordinary skill in the art. See In re Keller, 642 F.2d 413, 208 USPQ 871 (CCPA 1981). One having ordinary skill in the art would look at the system of Teo and see that there was a lack of reflux provided to the separation and would have considered it obvious to have provided that reflux for the benefit of increasing the methane separation in the column in the way as shown in the rejection above, and if there was any resulting “conflict” as applicant argues, would consider it an operational trade-off for the benefit of providing a leaner gas product.
Applicant further argues, page 8 that “the gas recycled via the claimed therefore does not have the same composition as the gas recycled in Mak” corresponding to declaration 12 and the “criticality of this difference in composition is readily appreciated in a case of process upset” where in Mak when a process upset occurs, “the mass separation between methane and ethane will be affected” results in a “snowball effect”. This is not persuasive.
Applicant’s arguments and the declarations here are only considering Mak individually and not the combination. 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). The arguments and statements in this regard are to an alleged upset condition in Mak but do not take into consideration the combination or Teo.
Applicant further argues, that if the same upset occurs in the present invention the change in the quantiles of ethane in the feed gas will have a have an effect on the flash gas operation which is contrary to what is disclosed in Mak which corresponds the statements in the declaration 15.
Applicant argues, pages 9-10 that “’if the main reflux becomes depleted in methane, the ethane separation rate in the column decreases, and the quality of the head stream produced at the head of the column deteriorates further, aggravating the methane depletion of the main reflux” and the “aim of the invention is to provide a flexible and very efficient method for extracting ethane… wherein the ethane extraction rate is not at all or only slightly affected when fluctuations occur in the quality of the head of the separation column” and as Teo and Mak contrast “Mak cannot be applied to Teo without breaking convention and therefore one having ordinary skill in the art would not be motivate to make such a combination” without impermissible hindsight. This is not persuasive.
In response to applicant's argument that the combination would result in preventing the alleged “snowball effect”, the fact that the inventor has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the differences would otherwise be obvious. See Ex parte Obiaya, 227 USPQ 58, 60 (Bd. Pat. App. & Inter. 1985). Applicant has not provided any persuasive evidence or arguments that it would not have been obvious to have added reflux to Teo based on the teaching of Mak to decrease the overall ethane content of the overhead stream from the column. In response to 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). The use of a reflux stream in separation is well known as shown in Mak, and as Teo does not use one, merely modifying Teo to use an internal based reflux such as one taught by Mak would be well within ordinary skill in the art and be obvious to one having ordinary skill in the art to increase the methane ethane separation. Further, there are no “contrasting teachings” found in Teo or Mak as those alleged contrasts are based upon the arguments and statements, not what is found in either the teachings of Teo or Mak.
Applicant’s arguments in regards to the rejection under 35 USC 112(b) are not persuasive, as claim 4 recites “the at least one heat upstream heat exchanger” which is different than the limitation found in claim 1.
Applicant argues, page 13 that “Mak does not disclose the same configuration as Teo or the claimed invention upstream of the recycle stream” and as such it would not have been obvious “based on the teaching of Mak instead of recycling the flash gas stream back to the overhead fractionation column to have recycle the stream back through the heat exchangers, at least because Mak does not disclose any flash gas stream, or any fractionation column” and that the “recycled gas… is not the same gas that would be coming from separator of Teo”. This is not persuasive.
Both Teo and Mak the use of recycle streams, with them being used in different ways and both Teo and Mak teach the use of separation columns, as such when considering Teo and Mak, one having ordinary skill in the at would look at the stream being recycled in Teo and based on the teachings of Mak modify it to instead of recycling it back to upstream of compression, to have utilized to send to the fractionation column after cooling to provide separation as in Mak.
Mak further argues that there is “no evidence that the composition of gas would be the same so as to increase the recovery of methane in the overhead” and in the present invention “the recycle stream coming from the flow of flash gas is very rich in methane” and as Mak does not disclose these upstream components” it would not be obvious to have modified Teo without “using information gleaned from Applicant’s own disclosure” and a showing that a person could adapt a piece of art is inadequate to show obviousness. This is not persuasive.
While Mak does not teach a flash stream, the absorber column is also a fractionation column, which is producing an overhead natural gas stream and using it to form a reflux stream. Teo teaches the recycling of a stream formed of the overhead, but does not teach it being used for reflux. This stream would have a lower concentration of heavier components in the feed stream as it is formed of a flashed portion of the overhead of the column, so using it as reflux would increase the methane separation from those heavier components. Mak teaches that when a portion of an overhead stream is recycled, it can be recycled back for use as reflux, which one having ordinary skill in the art would recognize would increase the separation of the column. That Mak teaches different overall components than Teo does not change the compatibility and universality of the teaching of using a recycled portion of the overhead steam as reflux. Applicant further makes an argument of impermissible hindsight. In response to 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). Mak provides a clear teaching of using a recycled stream as reflux and as such it would have been obvious to a person skilled in the art to modify Teo based on the teaching of Mak.
Applicant does not provide any further arguments in regards to claim 14 other than referencing those already provided and as such those arguments have been addressed.
Conclusion
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/BRIAN M KING/ Primary Examiner, Art Unit 3763
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