Ex Parte Chantant

Patent Trial and Appeal Board

Jan 18, 2017

12668582 (P.T.A.B. Jan. 18, 2017)

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