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Патент USA US3092986

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June 11, 1963
H. HASHEMl-TAFRESHI
3,092,976
REFRIGERATION OF ONE FLUID BY HEAT EXCHANGE WITH ANOTHER
FiledJune 1. 1961
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Inventor
United States Patent O?ice
3,092,976
Patented June 11, 1963
1
2
The liquefaction in step (d) may of course be achieved
by indirect heat exchange with two or more cold ?uids
3,092,976
REFRIGERATION OF ONE FLUID BY HEAT
EXCHANGE WITH ANOTHER
if so desired.
.
Hadi Hashemi-Tafreshi, London, England, assignor to
Conch International Methane Limited, Nassau, The
Bahamas, a Bahamian company
Filed June 1, 1961, Ser. No. 114,198
6 Claims. (Cl. 62-117)
The second ?uid used in the method of this invention,
i.e. the refrigerant, may be any suitable volatile liquid
or lique?able gas, for example, ammonia, carbon dioxide,
sulphur dioxide, dichloroethylene, dichlorodi?uorometh
ane, methane, ethane, ethylene, propane, or butane.
The invention will now be illustrated by reference to
This invention relates to a novel method of refrigera 10 the accompanying drawings in which FIGURE I is a flow
tion.
sheet of an ethylene refrigeration cycle used to cool an
The basic principle involved in refrigerating systems of
other ?uid, for example natural gas at 1500 p.s.i.a., from
the compression type is that of transferring heat from an
—20° F. to —200° F., and FIGURE II is a ?ow sheet
environment at low temperature to one at a higher tem
of an ammonia refrigeration cycle used to cool another
perature by causing a volatile liquid, usually called the 15 ?uid, for example ethylene at 300 p.s.i.a.,, from 100° F. to
refrigerant, to absorb heat at the low temperature by
° F.
vapourisation and to dissipate this heat at the high tem
perature by condensation. Vapourisation and condensa
Referring to FIGURE I the ?uid to be cooled from
--20° F. to -200° F., for example natural gas at 1500
tion are respectively induced by maintaining a lower or
p.s.i.a., is passed through pipe 1 in heat exchanger 2. In
higher pressure than the saturation pressures of the refrig 20 this heat exchanger the cooling is achieved by liquid ethyl
erant at the lower and higher temperatures.
ene at 320 p.s.i.a. and an inlet temperature of ——205" F.
This system in which heat is absorbed by the refrigerant
passing
through pipe 3. The liquid ethylene leaves the
during its evaporation requires that the whole of the va
heat
exchanger
at —32° F. but is still a liquid. This liq
pour produced be compressed from the lowest pressure in
the system to the highest. If the evaporation took place 25 uid passes to expansion valve 4 and then into expansion
chamber 5, the drop in pressure being sufiicient to lower
in stages, each at a lower pressure, the total compressor
the
temperature in expansion chamber 5 to —63° F. The
work required to recompress these gases to the highest
liquid from expansion chamber 5 passes to expansion
pressure in the system would be less. Up to the present,
chamber 7 the pressure being reduced in expansion valve
‘the only way of achieving this reduction in work has been
6
'by an amount su?icient to reduce the temperature to
to have a series of the evaporation heat exchangers op 30
-—l02°
F. The liquid from expansion chamber 7 passes
erating at successively lower pressures but this involves
to expansion chamber 9 through expansion valve 8, the
‘a considerable amount of plant.
drop in pressure being su?icient to reduce temperature in
We have now found that if in a refrigeration system of
expansion
chamber 9 to —13l° F. The liquid in expan
the compression type the refrigerant is caused to absorb
sion chamber 9 passes to expansion chamber 11 via ex
heat while being maintained in a'liquid condition, and 35 pansion
valve 10, the drop in pressure being su?icient to
the vapourisation takes place in stages thereafter, a con
reduce the temperature in expansion chamber 11 to —174°
siderable saving in compressor work is effected without
F. The liquid in expansion chamber 11 passes to expan
having to use a plurality of evaporator heat exchangers.
sion chamber 13 via expansion valve 12, the drop in pres
Accordingly, the present invention provides a method
of cooling a ?rst ?uid with a second ?uid which com 40 sure being su?icient to reduce the temperature in expan<
prises:
sion chamber 13 to —206° F.
(a) passing the second ?uid as a liquid at a temperature
lower than that of the ?rst ?uid in indirect heat ex
pipe 14 to compressor 15 in which its pressure is raised
to 320 p.s.i.a. From compressor 15 the liquid passes
change with the?rst ?uid, the pressure of the second
?uid being such that it remains as a liquid throughout
via pipe 3 through heat exchanger 2 to complete the cycle.
The gas phase in expansion chamber 13 at —206° F.
The liquid from expansion chamber 13 is passed via
such heat exchange step;
and 1.8 p.s.i.a. passes via pipe 16 to compressor 17 in
which the gas is raised to 7.5 p.s.i.a. This gas is mixed
(b) expanding the warmed second ?uid from the heat ex
change step in two or more expansion chambers in
with the gas leaving expansion chamber 11 in pipe 18
series to produce a cold second ?uid as a liquid and,
and passed to compressor 19 in which the gas is com
from each expansion chamber, a cold second ?uid as a 50 pressed to 30 p.s.i.a. The gas leaving compressor 19 joins
gas;
with the gas from expansion chamber 9 in pipe 20 and is
(0) recompressing the liquid from step (b) and recycling
fed to compressor 21. The exit gases from compressor
21 at 65 p.s.i.a. are joined with the gas from the ex
it to step (a);
(d) recompressing and liquefying and gases from step
(b), said liquefaction being effected by indirect heat
exchange with a third ?uid, and
55
pansion chamber 7 in pipe 22 and fed to compressor 23.
The exit gases from compressor 23 at 140 p.s.i.a. are
mixed with the gas from expansion chamber 5 in pipe
(e) recycling the compressed liquid from step (d) to the
24 and are fed to compressor 25.
expansion chambers of step (b).
The exit gases from compressor 25 at 300 p.s.i.a. are
Preferably in step (d) the gas from each expansion 60 then lique?ed by passage, ?rstly through water cooler 26,
secondly through heat exchanger 27, in which they are
chamber is recompressed to the pressure of the gaseous
e?'luent from the previous expansion chamber and is fed
into such e?luent for further recompression with it.
It is also possible to insert one or more expansion cham
cooled from 100° F. to —20° F. by indirect heat exchange
with liquid ammonia at —25° F. and 250 p.s.i.a. passing
through pipe 28, and, thirdly, through heat exchanger 29
bers in the path of the compressed liquid from step (d) 65 in which they are lique?ed at —20° F. by indirect heat
exchange with evaporating liquid ammonia in pipe 30.
to join up with the series of expansion chambers used in
The liqued ethylene at —-20° F. then passes via pipe 31
step (1)).
and
expansion valve 32 into expansion chamber 5 to com
Also if desired, subsidiary refrigeration can be ob
plete the gas cycle.
tained by using liquid from any of the expansion cham
As already explained, it is
bers in a normal evaporator type heat exchanger, recy 70 expansion chambers in the possible to insert one or more
path of the compressed liquid
cling the vapour produced to an appropriate compressor
from step (d), referred to above, to join up with the series
used in step (d).
of expansion
chambers used in step (b).
This can be
3,092,976
achieved, for example, in a modi?cation of the ?ow sheet
of FIGURE I made by joining the pipe carrying the
liquid ethylene after it leaves heat exchanger 2 to expan
sion valve 6 instead of expansion valve 4. Naturally with
such a change the temperature and pressure conditions
will have to be altered somewhat.
Referring to FIGURE II, the ?uid to be cooled from
100° F. to -—20° F. passes through pipe 40 in heat ex
changer 41 in which it is cooled by indirect heat exchange
with liquid ammonia passing through pipe 42 at an inlet 10
temperature of -25° F. and a pressure of 250 p.s.i.a.
The liquid ammonia leaving the heat exchanger 41 still
as a liquid at 75° F., passes through expansion valve 43
into expansion chamber 44, the drop in pressure being
su?icient to lower the temperature in expansion cham
ber 44 to 51° F. The liquid from expansion chamber
44 passes through expansion valve 45 to expansion cham
ber 46, the drop in pressure being su?icient to lower the
temperature to 9° F. The liquid from expansion cham
ber 46 passes to expansion chamber 47 via expansion
valve 48, the drop in pressure being su?icient to reduce
the temperature to —26° F. The liquid from expansion
chamber 47 is divided into two streams, one of which
passes through pipe 49 to compressor 50. The com
4
I claim.
1. A method of cooling a ?rst ?uid with a second ?uid
which comprises:
(a) passing the second ?uid as a liquid at a tempera
ture lower than that of the ?rst ?uid in indirect heat
exchange with the ?rst ?uid, the pressure of the sec
ond ?uid being such that it remains as a liquid
throughout such heat exchange step;
(b) expanding the warmed second ?uid from the heat
exchange step in a plurality of expansion chambers
in series to produce a cold second ?uid as a liquid
and, from each expansion chamber, a cold second
?uid as a gas;
(0) recomprcssing the liquid from step (b) and recy
cling it to step (a);
(d) recompressing and liquefying the gases from step
(b), said liquefaction being effected by indirect heat
exchange with a third ?uid, and
(e) recycling the compressed liquid from step (d) to
the expansion chambers of step (b).
2. A method as claimed in claim 1 in which the gas
from each expansion chamber is recompressed to the
pressure of the gaseous ef?uent from the previous expan
sion chamber and is fed into such e?luent for further
recompression with it.
pressed liquid from compressor 50 at 250 p.s.i.a. passes 25
3. A method as claimed in claim 2 which includes ex
through pipe 42 to complete the cycle.
pansion of the liquid resulting from the recompression and
The other portion of the liquid from expansion cham
liquefaction of the gases from the expansions in step (b)
ber 47 passed through pipe 51 and heat exchanger 52 in
prior to expansions in the expansion chambers of step
which it evaporates While further cooling or liquefying
(b) in which a further expansion chamber is inserted in
the ?uid originally cooled in heat exchanger 41. For 30 the path of the compressed liquid resulting from the re
example, if the ?uid in pipe 40 is ethylene and this leaves
compressing and liquefying of the gases from the said ex
heat exchanger 41 at —"'(]‘° F. it can be lique?ed at -20°
F. in the evaporator heat exchanger 52.
pansion chambers to join up with the said series of ex
pansion chambers.
After passing through heat exchanger 52 the ammonia
4. A method as claimed in claim 2 in which subsidiary
35
in vapour form is mixed via pipe 53 with the gaseous ef?u
refrigeration is obtained by passing liquid from one of
ent from expansion chamber 47 in pipe 54 and fed to
the expansion chambers to an evaporator type heat ex
compressor 55. The exit gas from compressor 55 at
changer and recycling the vapour produced to the ap
37.6 p.s.i.a. joins the gas from expansion chamber 46 in
propriate compressor used in recompressing the gases
pipe 56 and is fed to compressor 57. The compressed gas 40 from an expansion chamber.
from compressor 57 at 91 p.s.i.a. is coiled in water cooler
5. A method as claimed in claim 2 in which the sec
58 and then joins the gas from expansion chamber 44 in
ond ?uid is selected from the group of refrigerants con
pipe 59 and passes to compressor 60. The compressed
sisting of ammonia, carbon dioxide, sulphur-dioxide, di
ammonia from compressor 60 passes through water cool
chloroethylene, dichlorodi?uoromethane, methane, eth
er 61 in which it is lique?ed at 100° F., and thence
ane, ethylene, propane and butane.
through expansion valve 62 into expansion chamber 44
to complete the gas cycle. If it is desired to cool the
compressor suction, a part of the liquid ammonia leav
ing water cooler 61 can be fed back via pipes 63, 64 and
65 to appropriate stages in the gas compression system. r
Preferably all the compressors in this ammonia refrig
eration system are reciprocating compressors.
6. A method as claimed in claim 1 in which the sec
ond ?uid is ammonia, and the third ?uid is water.
References Cited in the ?le of this patent
FOREIGN PATENTS
788,247
822,122
Great Britain ________ __ Dec. 23, 1957
Great Britain ________ _.. Oct. 21, 1959
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