Ex Parte ChantantDownload PDFPatent Trial and Appeal BoardJan 18, 201712668582 (P.T.A.B. Jan. 18, 2017) Copy Citation United States Patent and Trademark Office UNITED STATES DEPARTMENT OF COMMERCE United States Patent and Trademark Office Address: COMMISSIONER FOR PATENTS P.O.Box 1450 Alexandria, Virginia 22313-1450 www.uspto.gov APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO. 12/668,582 01/11/2010 Francois Chantant TS8688USAP 7208 23632 7590 01/20/2017 SHF! T OH miUPANY EXAMINER P O BOX 2463 MENGESHA, WEBESHET HOUSTON, TX 77252-2463 ART UNIT PAPER NUMBER 3744 NOTIFICATION DATE DELIVERY MODE 01/20/2017 ELECTRONIC Please find below and/or attached an Office communication concerning this application or proceeding. The time period for reply, if any, is set in the attached communication. Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the following e-mail address(es): USPatents@Shell.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte FRANCOIS CHANT ANT Appeal 2015-004497 Application 12/668,582 Technology Center 3700 Before STEFAN STAICOVICI, JAMES P. CALVE, and LEE L. STEPINA, Administrative Patent Judges. CALVE, Administrative Patent Judge. DECISION ON APPEAL STATEMENT OF THE CASE Appellant appeals under 35U.S.C. § 134 from the final rejection of claims 1—6 and 8—18. Appeal Br. 2. Claim 7 is cancelled. Id. at 10 (Claims Appendix). We have jurisdiction under 35 U.S.C. § 6(b). We REVERSE. Appeal 2015-004497 Application 12/668,582 CLAIMED SUBJECT MATTER Claims 1 and 14 are independent. Claim 1 is reproduced below. 1. A method of liquefying a gaseous hydrocarbon stream, the method at least comprising the steps of: (a) providing a feed stream comprising the gaseous hydrocarbon stream at an elevated pressure; (b) dividing the feed stream of step (a) to provide at least a first stream and a second stream; (c) expanding the first stream or compressing the second stream, or both; (d) cooling and liquefying the first stream downstream of step (c) by heat exchanging exclusively against a liquid nitrogen stream that is at a pressure of less than 10 bara, to provide a first liquefied hydrocarbon stream and an at least partly evaporated nitrogen stream; and (e) cooling and liquefying the second stream downstream of step (c) by heat exchanging against the at least partly evaporated nitrogen stream of step (d) without invoking a significant change in pressure of the evaporated nitrogen stream other than a de minemus operational pressure loss caused by the present heat exchanging of step (e) and passing the evaporated nitrogen stream from the heat exchanging of step (d) to the present heat exchanging of step (e), wherein the cooling of the first stream and second stream is carried out at different pressures. REJECTION Claims 1—6 and 8—18 are rejected under 35 U.S.C. § 103(a) as being unpatentable over Forg (DE 19600515, pub. May 27, 1971) and Grossmann (US 3,194,025, iss. July 13, 1965). 2 Appeal 2015-004497 Application 12/668,582 ANALYSIS The main issue on appeal is whether it would have been obvious to modify the hydrocarbon liquefying method and apparatus of Forg to heat exchange a first stream of gaseous hydrocarbon exclusively against a liquid nitrogen stream that is at a pressure of less than 10 bara, as recited in claims 1 and 14, the independent claims on appeal. We agree with Appellant that it would not have been obvious to do so based on Grossman’s teaching of liquefaction of natural gas with a nitrogen refrigerant at 15 psia. Final Act. 3^4. We understand 15 psia as equivalent to about one bara or one atmosphere (ata) absolute pressure.1 Modifying Forg2 to heat exchange against a liquid nitrogen stream at 15 psia would thus satisfy the requirement that the liquid nitrogen pressure is less than 10 bara. However, Grossman teaches that the nitrogen stream at 15 psia is a nitrogen gas rather than a liquid nitrogen stream, as claimed. See Grossman, 2:8—12. Appellant also argues persuasively that cooling a refrigerant stream of nitrogen to -240 °F at a pressure of 15 psia, as taught in Grossman, would produce a nitrogen vapor because the boiling point of nitrogen at 15 psia is — 320 °F. Br. 6; Grossman, 2:70—72; Final Act. 3^4 (citing id. at 2:10, 70). The Examiner has not challenged that assertion and refers to Grossman’s “nitrogen refrigerant.” See Ans. 7, 11; Final Act. 3^4. Thus, the Examiner’s determination that it would have been obvious to adjust the pressure of the liquid nitrogen from pump 6 of Forg based on Grossman’s use of a nitrogen gas refrigerant at 15 psia is not supported by a rational underpinning. 1 One (1) bar equals about 14.50 pounds per square inch (psi) of pressure and about one (1) atmosphere (atm) or atmosphere absolute (ata). 2 The Examiner and Appellant refer to this reference as “Foerg.” 3 Appeal 2015-004497 Application 12/668,582 The Examiner alternatively rejected claims 1 and 14 by finding that Forg teaches every limitation of those claims including a liquid nitrogen stream at 14 ata (similar to 14 bara) that approximates the claimed liquid nitrogen stream of less than 10 bara and therefore that it would have been obvious to modify Forg to arrive at the claimed liquid nitrogen pressure of less than 10 bara. Ans. 5—6; Final Act. 2—3. The Examiner offered several rationales. The Examiner determined that selecting a specific refrigerant pressure depends on the temperature and pressure of the natural gas and thus “would have flown naturally to one of ordinary skill in the art as necessitated by the specific requirements of a given application.” Id. at 3. The Examiner also determined that selecting/adjusting the pressure of the liquid nitrogen exiting from pump 6 of Forg would have been known to a skilled artisan “as part of mechanical expedient necessitated by the specific requirements of a given application.” Ans. 5. The Examiner further found that Forg teaches the claimed invention except for the exact pressure value and concluded that it would have been obvious to adjust the nitrogen refrigerant pressure “since it has been held that discovering an optimum value of a result effective variable involves only routine skill in the art.” Id. at 5—6, 9—10. While we appreciate the Examiner’s analysis and findings that Forg substantially discloses the method and apparatus as recited in claims 1 and 14, nonetheless, we find that the Examiner’s reason for modifying Forg is not supported by rational underpinning. The Examiner has not established that Forg cools a first gaseous hydrocarbon stream exclusively against a liquid nitrogen stream, as claimed, because the hydrocarbon stream is cooled and liquefied in heat exchanger 4 by liquid nitrogen from pump 6 and also by evaporated nitrogen stream from turbine 7. Forg, Fig. 1; see Br. 4. 4 Appeal 2015-004497 Application 12/668,582 Forg discloses that the evaporated nitrogen stream from turbine 7 also enters the cold end of heat exchanger 4 where it is heated from 81 °K and 1.6 ata to 108 °K and 1.6 ata. Forg, 4:32—35 (translation). Although Forg also discloses that the liquid nitrogen provides the necessary cooling to liquefy the gaseous hydrocarbon gas in heat exchanger 4 {id. at 4:20-24) as the Examiner found (Ans. 2—3, 4), nonetheless, we find sufficient evidence to indicate that the evaporated nitrogen stream from turbine 7 also provides some of the cooling energy for liquefying the gaseous hydrocarbon stream.3 Even if the first gaseous hydrocarbon steam is cooled and liquefied exclusively against a liquid nitrogen stream in Forg, the Examiner’s reasons for modifying Forg to render obvious the claimed pressure of less than 10 bara are not supported by rational underpinning because Forg discloses that its liquefaction process and apparatus are designed for liquid nitrogen that is pumped to a “higher pressure” before the heat exchanger. Forg, 1:1—3. In addition, Forg teaches that the liquid nitrogen, which is stored at a pressure of 1 ata, must be increased to 14 ata prior to the heat exchanger for methane gas. Id. at 3:36-40. Forg discloses that by increasing the pressure of liquid nitrogen gas to 14 ata via pump 6, the liquid nitrogen becomes evaporated and unpressurized by heat exchange with the methane. Id. at 4:26—27. In view of these disclosures, the Examiner has not provided sufficient technical or scientific reasoning as to why a skilled artisan would have been motivated to reduce the pressure of the liquid nitrogen in Forg from 14 ata (14 bara) to less than 10 bara, as claimed. 3 We also note that Appellant’s Specification discusses Forg (DE 1960515) and indicates that Figures 1 and 2 of Forg disclose a gas hydrocarbon stream being “liquefied in a heat exchanger by heat exchanging against the liquid nitrogen which evaporates as a result.” Spec. 2:6—12. 5 Appeal 2015-004497 Application 12/668,582 Treating the proposed modification as a mere mechanical expedient or a natural outflow or design choice (Final Act. 3; Ans. 5) is not supported by a rational underpinning in view of Forg’s disclosure that the liquid nitrogen is pumped to 14 ata as a necessary part of the liquefaction process. For similar reasons, the Examiner’s determination that the claimed liquid nitrogen pressure of less than 10 bara can be arrived at through routine experimentation to achieve an optimal result is not supported by a rationale underpinning or a preponderance of the evidence. Forg teaches that liquid nitrogen pressure should be increased from 1 ata in storage to 14 ata prior to entry into heat exchanger 4. The Examiner has not explained sufficiently why a skilled artisan would have been motivated to introduce liquid nitrogen into heat exchanger 4 at less than 10 bara, as claimed, when Forg teaches that 14 ata (14 bara) is desired for the hydrocarbon gas liquefaction process, or why such a reduction (rather than a further increase) in pressure would have been considered to be an optimal Forg’s liquefaction method.4 Thus, we do not sustain the rejection of claims 1—6 and 8—18. DECISION We reverse the rejection of claims 1—6 and 8—18. REVERSED 4 Appellant discloses the claimed method as reducing the operational cost of liquefaction and the need for equipment compared to DE 1960515 at the cost of liquefaction efficiency. Spec. 6:15—29, 8:13—24. 6 Copy with citationCopy as parenthetical citation