U.S. patent application number 12/933571 was filed with the patent office on 2011-01-27 for method for vaporizing cryogenic liquid through heat exchange using calorigenic fluid.
This patent application is currently assigned to L'Air Liquide Societe Anonyme Pour L'Etude Et L'Exploitation Des Procedes Georges Claude. Invention is credited to Maurice Bosquain, Alain Briglia, Philippe Grigoletto, Daniel Machon Diez De Baldeon, Marc Wagner.
Application Number | 20110017429 12/933571 |
Document ID | / |
Family ID | 39736847 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110017429 |
Kind Code |
A1 |
Bosquain; Maurice ; et
al. |
January 27, 2011 |
Method For Vaporizing Cryogenic Liquid Through Heat Exchange Using
Calorigenic Fluid
Abstract
A method of vaporizing cryogenic liquid, for example liquefied
natural gas, by heat exchange with a calorigenic fluid, for example
gaseous nitrogen is provided.
Inventors: |
Bosquain; Maurice;
(Sommecaise, FR) ; Wagner; Marc; (Saint Maur Des
Fosses, FR) ; Grigoletto; Philippe; (Villeparisis,
FR) ; Machon Diez De Baldeon; Daniel; (Paris, FR)
; Briglia; Alain; (Corze, FR) |
Correspondence
Address: |
American Air Liquide, Inc.;Intellectual Property Dept.
2700 Post Oak Boulevard, Suite 1800
Houston
TX
77056
US
|
Assignee: |
L'Air Liquide Societe Anonyme Pour
L'Etude Et L'Exploitation Des Procedes Georges Claude
|
Family ID: |
39736847 |
Appl. No.: |
12/933571 |
Filed: |
March 12, 2009 |
PCT Filed: |
March 12, 2009 |
PCT NO: |
PCT/FR09/50410 |
371 Date: |
September 20, 2010 |
Current U.S.
Class: |
165/104.19 |
Current CPC
Class: |
F17C 2265/05 20130101;
F17C 9/02 20130101; F25J 2290/90 20130101; F25J 2210/62 20130101;
F17C 2227/0309 20130101; F28D 9/00 20130101; F28F 3/005 20130101;
F25J 3/04272 20130101; F17C 7/04 20130101; F28D 2021/0033 20130101;
F25J 5/002 20130101; F25J 2250/42 20130101 |
Class at
Publication: |
165/104.19 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 27, 2008 |
FR |
0851970 |
Claims
1-10. (canceled)
11. A method for heating up a first fluid by heat exchange with a
second fluid in a plate and fin heat exchanger in which the first
fluid is heated up in a first series of separated passages and the
second fluid is cooled down in a second series of separated
passages, comprising: separating each passage of the first series
from the nearest passage of the second series by an auxiliary
passage containing fins in which an inert gas circulates.
12. The method of claim 11, wherein the first fluid consists of
liquefied natural gas which is heated in the first series of
separated passages.
13. The method of claim 11, wherein the first fluid consists of
liquefied natural gas which is vaporized in the first series of
separated passages.
14. The method of claim 11, wherein the second fluid consists of
gaseous nitrogen which cools in the second series of separated
passages.
15. The method of claim 11, wherein the second fluid consists of
gaseous nitrogen which liquefies in the second series of separated
passages.
16. The method of claim 11, wherein the inert gas is at a pressure
at least 0.1 bar higher than those of the first fluid and of the
second fluid.
17. The method of claim 11, wherein the inert gas is at a pressure
at least 0.5 bar higher than those of the first fluid and of the
second fluid.
18. The method of claim 11, wherein the inert gas is at a pressure
at least 0.1 bar lower than those of the first fluid and of the
second fluid.
19. The method of claim 11, wherein the inert gas is at a pressure
at least 0.5 bar lower than those of the first fluid and of the
second fluid.
20. The method of claim 11, wherein the inert gas is gaseous
nitrogen.
21. The method of claim 11, wherein the inert gas sent into at
least certain auxiliary passages is then sent to the
atmosphere.
22. The method of claim 11, wherein the inert gas sent into at
least certain auxiliary passages is then sent to a flare.
23. The method of claim 11, wherein at least one inlet and/or
outlet box of one of the first and second fluids is separated from
the passages in which the other of the first and second fluids
circulates by means of a double bar system.
24. The method of claim 23, wherein said double bar system
comprises bars separated by a dead zone.
25. The method of claim 11, wherein the first fluid is heated up at
a pressure of at least 60 bar abs.
26. A method of starting a plate and fin heat exchanger in which,
at full capacity, a first fluid is heated up by heat exchange with
a second fluid in a plate and fin heat exchanger, the first fluid
being heated up in a first series of separated passages and the
second fluid being cooled down in a second series of separated
passages, comprising separating each passage of the first series
from the nearest passage of the second series by an auxiliary
passage containing fins and in which during start-up an inert gas
at a temperature lower than ambient temperature, possibly at
cryogenic temperature, is sent into at least one auxiliary passage
in order to get down to temperature more swiftly.
27. The method of claim 26, wherein during start-up said inert gas
has a cryogenic temperature.
Description
[0001] The present invention relates to a method of vaporizing
cryogenic liquid, for example liquefied natural gas, by heat
exchange with a calorigenic fluid, for example gaseous
nitrogen.
[0002] In order to heat up and vaporize cryogenic liquids of the
liquefied natural gas (LNG) or equivalent type against a
calorigenic fluid, in order to recover the cold energy from the
LNG, use has, in the past, been made of one of the following three
options: [0003] a technology that consists in coiling into the form
of a pancake coil a system comprising two tubes that are joined
together by a tie. The tubes are welded or expanded onto manifolds
transverse to the pancake coils; [0004] brazed plate and fin
exchangers; [0005] wound tubular exchangers.
[0006] If there is a wish to recover the cold energy in order to
liquefy air gases, it is absolutely essential to avoid accidental
contamination of the nitrogen or the oxygen with a hydrocarbon gas,
especially when the natural gas is circulating through the
exchanger at a pressure higher than that of the air gas.
[0007] Tubular geometries are not very thermally efficient and
often lead to costly over engineering.
[0008] Moreover, existing methane terminals and existing air
separation plants do not always have the equipment required to
avoid sharp thermal transients during shut downs and restarts, and
this leads to thermal shock and therefore damage to the
exchangers.
[0009] One subject of the invention is a method for heating up a
first fluid by heat exchange with a second fluid in a plate and fin
heat exchanger in which the first fluid is heated up in a first
series of separated passages and the second fluid is cooled down in
a second series of separated passages, characterized in that each
passage of the first series is separated from the nearest passage
of the second series by an auxiliary passage containing fins in
which an inert gas circulates.
[0010] Optionally: [0011] the first fluid consists of liquefied
natural gas which is vaporized or heated up in the first series of
separated passages; [0012] the second fluid consists of gaseous
nitrogen which is cooled down or liquefies in the second series of
separated passages; [0013] the inert gas is at a pressure of at
least 0.1 bar or even at least 0.5 bar higher than those of the
first fluid and of the second fluid; [0014] the inert gas is at a
pressure of at least 0.1 bar, or even at least 0.5 bar lower than
those of the first fluid and of the second fluid; [0015] the inert
gas is gaseous nitrogen; [0016] the inert gas sent into at least
certain auxiliary passages is then sent to the atmosphere or to a
flare; [0017] at least one inlet and/or outlet box of one of the
first and second fluids is separated from the passages in which the
other of the first and second fluids circulates by means of a
double bar system, the bars possibly being separated by a dead
zone; [0018] the first fluid is heated up at a pressure of at least
60 bar abs.
[0019] Another subject of the invention is a method of starting a
plate and fin heat exchanger in which, at full capacity, a first
fluid is heated up by heat exchange with a second fluid in a plate
and fin heat exchanger, the first fluid being heated up in a first
series of separated passages and the second fluid being cooled down
in a second series of separated passages, characterized in that
each passage of the first series is separated from the nearest
passage of the second series by an auxiliary passage containing
fins and in which during start-up an inert gas at a temperature
lower than ambient temperature, possibly at cryogenic temperature,
is sent into at least one auxiliary passage in order to get down to
temperature more swiftly.
[0020] The invention will be described in greater detail with
reference to the figures.
[0021] FIGS. 1 to 3 show a cross section, taken in the lengthwise
direction of the exchanger, of each type of passage for an
exchanger operating in accordance with the invention. FIG. 1
depicts an auxiliary, inert gas passage, FIG. 2 an LNG passage, and
FIG. 3 a passage for nitrogen that is to be heated.
[0022] FIGS. 4 to 6 depict another exchanger operating in
accordance with the invention. FIG. 4 shows a cross section through
the parallel passages of the exchanger in the widthwise direction
of the exchanger, FIG. 5 shows a low-pressure nitrogen passage
sectioned in its lengthwise direction and FIG. 5 shows an LNG
passage section in its lengthwise direction. According to the
invention, a passage of the type of FIG. 1 will be positioned
between each passage of the type of FIG. 2 and each type of FIG. 3.
Thus, each passage of series of the type of FIG. 2 is separated
from each passage of the series of the type of FIG. 3 by a passage
of the type of FIG. 1 to form a brazed plate and fin exchanger made
of aluminum or some other material. In order to simplify the
drawing, the fins have not been illustrated.
[0023] FIG. 1 is the auxiliary, low-pressure inert gaseous nitrogen
passage, the inlet 9 of which is bottom right and the outlet 11 of
which is top left.
[0024] FIG. 2 illustrates a passage for heating up liquefied
natural gas (LNG) which enters the passage at bottom left 1 and
emerges top right 3. A double bar isolates the top and the bottom
of the LNG passage from the inert nitrogen passage.
[0025] FIG. 3 shows a passage for the cooling of high-pressure
gaseous nitrogen which enters the top of the passage through the
inlet 7 and emerges at the bottom through the outlet 5. The
high-pressure gaseous nitrogen passage is not as wide as the
low-pressure nitrogen passages of FIG. 1 or as the liquefied
natural gas passages of FIG. 2.
[0026] To avoid the nitrogen becoming contaminated with the
liquefied natural gas, an auxiliary passage is interposed between
each pair of nitrogen and LNG passages. The exchange of heat
between the nitrogen and LNG passages will be via the fins of the
auxiliary passage, by conduction. Obviously, the corrugation chosen
for the auxiliary passage will have an optimal height/thickness
ratio.
[0027] In the case illustrated, the auxiliary passages will be
swept with low-pressure gaseous nitrogen (at a pressure lower than
that of the LNG of FIG. 2 and than that of the nitrogen of FIG. 3)
and collected for discharging to the atmosphere or possibly to a
flare.
[0028] The boxes which cover the stack and may therefore be sources
of contamination, will therefore be isolated from the other fluid
using dead zones Z.
[0029] Gas from the dead zones Z will be collected, and these zones
may possibly be swept with low-pressure nitrogen.
[0030] The above dead zones may be isolated from the LNG and
nitrogen circuits by means of a double bar 2 system in order to
improve sealing. Gases from the clearance space between the double
bars 2 may itself be collected in order to improve intrinsic
safety. This is explained in greater detail in respect of the
method of FIGS. 5 and 6 but applies equally to the method of FIGS.
1 to 3.
[0031] The passages of FIG. 1 are used during start-ups to bring
the exchanger down to temperature gradually and in a controlled
manner using a flow of low-pressure nitrogen drawn from an
auxiliary volume.
[0032] According to another aspect of the invention which is
illustrated in FIG. 4, each passage for nitrogen that is to be
heated up (N.sub.2 LP) is isolated from the passages for LNG to be
vaporized by a passage containing a high-pressure inert process gas
(N.sub.2 HP), in this case nitrogen at a higher pressure than the
nitrogen that is to be heated up (35 bar) and than the liquefied
natural gas that is to be vaporized (15 bar).
[0033] As can be seen in FIGS. 5 and 6, the bars which separate a
circuit for nitrogen that is to be heated up from an LNG circuit
are duplicated so that the space between them forms a dead zone Z
open to the atmosphere via a vent V, so that any leak of liquefied
natural gas can escape via this route. The passages in FIGS. 5 and
6 are separated by a high-pressure inert gas passage.
* * * * *