U.S. patent application number 14/116576 was filed with the patent office on 2014-03-13 for cryogenic cooling device and method.
This patent application is currently assigned to L'Air Liquide Societe Anonyme Pour L'Etude Et L'Exploitation Des Procedes Georges Claude. The applicant listed for this patent is Fabien Durand. Invention is credited to Fabien Durand.
Application Number | 20140069116 14/116576 |
Document ID | / |
Family ID | 46146943 |
Filed Date | 2014-03-13 |
United States Patent
Application |
20140069116 |
Kind Code |
A1 |
Durand; Fabien |
March 13, 2014 |
CRYOGENIC COOLING DEVICE AND METHOD
Abstract
Cryogenic cooling method and device comprising a main cryogenic
cooler comprising a cold head positioned in a first chamber
selectively placed under vacuum, a reservoir of working fluid
placed in a second chamber selectively placed under vacuum, a
member to be cooled being placed in the reservoir in heat exchange
with the working fluid, the cold head of the main cryogenic cooler
being thermally connected to a heat exchanger which is itself
fluidically connected to the reservoir via pipes forming a first
circulation loop for the working fluid, the pipes passing from the
first to the second chamber, characterized in that the volumes
selectively under vacuum of the first and second chambers are
independent and in that the device comprises a secondary cryogenic
cooler comprising a cold head placed in a third chamber selectively
placed under vacuum, the cold head of the secondary cryogenic
cooler being thermally connected to a heat exchanger which is
itself fluidically connected to the reservoir via pipes forming a
second circulation loop for the working fluid, and in that the
volume selectively under vacuum of the third chamber is independent
of the volumes selectively under vacuum of the first and second
chambers.
Inventors: |
Durand; Fabien; (Voreppe,
FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Durand; Fabien |
Voreppe |
|
FR |
|
|
Assignee: |
L'Air Liquide Societe Anonyme Pour
L'Etude Et L'Exploitation Des Procedes Georges Claude
Paris
FR
|
Family ID: |
46146943 |
Appl. No.: |
14/116576 |
Filed: |
April 20, 2012 |
PCT Filed: |
April 20, 2012 |
PCT NO: |
PCT/FR2012/050864 |
371 Date: |
November 8, 2013 |
Current U.S.
Class: |
62/6 |
Current CPC
Class: |
F25B 25/005 20130101;
F25B 2400/17 20130101; F25B 2400/06 20130101; F25D 19/00 20130101;
F25B 9/14 20130101 |
Class at
Publication: |
62/6 |
International
Class: |
F25B 9/14 20060101
F25B009/14 |
Foreign Application Data
Date |
Code |
Application Number |
May 9, 2011 |
FR |
1153941 |
Claims
1-13. (canceled)
14. A cryogenic cooling device comprising a main cryocooler with a
cold head arranged in a first chamber placed under vacuum, a
reservoir of working fluid arranged in a second chamber placed
under vacuum, a member that is to be cooled being arranged in the
reservoir in a heat exchange relationship with the working fluid,
and a secondary cryocooler comprising a cold head arranged in a
third chamber placed under vacuum, wherein: the cold head of the
main cryocooler is thermally connected to a heat exchanger, itself
fluidically connected to the reservoir via pipes forming a first
circulation loop for the working fluid, the pipes passing from the
first to the second chamber; the volumes under vacuum of the first
and second chambers are independent which means to say that the
vacuums in the first and second chambers are independent; the cold
head of the secondary cryocooler is thermally connected to a heat
exchanger, itself fluidically connected to the reservoir via pipes
forming a second circulation loop for the working fluid; and the
volume under vacuum of the third chamber is independent of the
volumes under vacuum of the first and second chambers which means
to say that the vacuums of the first, second and third chambers are
independent.
15. The device of claim 14, wherein at least one of the first and
third chambers is sealed off by at least one selectively removable
cap.
16. The device of claim 15, wherein at least one selectively
removable cap is arranged in the lower part of the chamber such
that it is adjacent to the cold head.
17. The device of claim 15, wherein at least one cap is mounted in
a sealed fashion on the body of the chamber via fixing screws.
18. The device of claim 14, further comprising, around the pipes
passing from the first to the second chamber, vacuum barriers which
separate the volumes under vacuum of the first and second chambers,
the vacuum barriers being arranged in at least one tubular portion
that connects the first and second chambers.
19. The device of claim 14, further comprising, around the pipes
passing from the third to the second chamber, vacuum barriers which
separate the volumes under vacuum of the third and second chambers,
the vacuum barriers being arranged in at least one tubular portion
that connects the third and second chambers.
20. The device of claim 14, wherein the cold head of the
cryocooler(s) is associated with a heat exchanger that acts as a
condenser for the working fluid.
21. The device of claim 14, wherein the cold head of the main
cryocooler is connected to the reservoir via two pipes the upstream
ends of which are connected to a hermetic volume arranged under the
cold head of the main cryocooler, the downstream ends of the pipes
being connected to an upper end of the reservoir via a vertical or
substantially vertical portion.
22. The device of claim 14, wherein the cold head of the secondary
cryocooler is connected to the reservoir via two pipes the upstream
ends of which are connected to a hermetic volume arranged under the
cold head of the secondary cryocooler and the downstream ends of
which are connected to an upper end of the reservoir via a vertical
or substantially vertical portion.
23. A method for cooling a member to a low temperature using the
cryogenic cooling device of claim 14, wherein the main cryocooler
is used to cool the member, the first chamber and the second
chamber are placed under vacuum and the secondary cryocooler is
selectively switched off or on while the main cryocooler is in
operation.
24. The method of claim 23, wherein the main cryocooler is switched
off, and at the same time or before the main cryocooler is switched
off, the secondary cryocooler is started in order to cool the
member, the third chamber being placed under vacuum or kept under
vacuum.
25. The method of claim 23, wherein when a cryocooler is switched
off, the cold head of the cryocooler switched off is heated up to
an ambient temperature using at least one of the following steps:
spontaneous natural heating; by commanded active heating; by forced
circulation of gas at ambient temperature into the chamber of the
cryocooler or around the exchangers via a coiled tube or any other
device; and by bringing the volume of the cryocooler chamber to
atmospheric pressure.
26. The method of claim 23, further comprising a step of repairing
or maintaining one of the two cryocoolers while the other
cryocooler is in operation and is cooling the member, the method
comprising: shutting down the cryocooler intended to undergo repair
or maintenance or keeping it in the switched off state; keeping the
cryocooler intended to undergo repair or maintenance at ambient
temperature or bringing it to ambient temperature; opening the
chamber containing the cryocooler intended to undergo repair or
maintenance; dismantling the cryocooler intended to undergo repair
or maintenance so that it can be replaced or repaired without
connected the hermetic volume to the atmosphere; and maintaining
the vacuum within the chamber of the other cryocooler that is in
operation and in the second chamber.
Description
[0001] The present invention relates to a cryogenic cooling device
and method.
[0002] It should be noted that the work leading up to the present
invention enjoyed funding from the European Union 7.sup.th
framework program FP/2007-2013 under grant No. 241285.
[0003] The invention relates more particularly to a cryogenic
cooling device comprising a main cryocooler with a cold head
arranged in a first chamber selectively placed under vacuum, a
reservoir of working fluid arranged in a second chamber selectively
placed under vacuum, a member that is to be cooled being arranged
in the reservoir in a heat exchange relationship with the working
fluid, the cold head of the main cryocooler being thermally
connected to a heat exchanger, itself fluidically connected to the
reservoir via pipes forming a first circulation loop for the
working fluid, the pipes passing from the first to the second
chamber.
[0004] Document US20090049862A1 describes a refrigeration device
using a cryocooler to liquefy a working fluid, for example
nitrogen. The liquefied working fluid is used in the conventional
way to cool an application to a very low temperature, typically
superconductor cables.
[0005] In sensitive electrical applications, this type of cooler
has to be able to operate uninterrupted. However, the known
solutions do not allow the refrigeration device to undergo
maintenance or repair in a way that is simple and easy for an
operator and minimizes the impact on the production of cold.
[0006] It is an object of the present invention to alleviate all or
some of the abovementioned disadvantages of the prior art.
[0007] To this end, the device according to the invention, which in
other respects is in accordance with the generic definition thereof
given in the above preamble, is essentially characterized in that
the volumes selectively under vacuum of the first and second
chambers are independent and in that the device comprises a
secondary cryocooler comprising a cold head arranged in a third
chamber selectively placed under vacuum, the cold head of the
secondary cryocooler being thermally connected to a heat exchanger,
itself fluidically connected to the reservoir via pipes forming a
second circulation loop for the working fluid, and in that the
volume selectively under vacuum of the third chamber is independent
of the volumes selectively under vacuum of the first and second
chambers.
[0008] Furthermore, some embodiments of the invention may include
one or more of the following features: [0009] out of the first and
third chambers, at least one is sealed off by at least one
selectively removable cap; [0010] at least one selectively
removable cap is arranged in the lower part of the chamber such
that it is adjacent to the cold head; [0011] at least one cap is
mounted in a sealed fashion on the body of the chamber via fixing
screws; [0012] the device comprises, around the pipes passing from
the first to the second chamber, vacuum barriers which separate the
volumes selectively under vacuum of the first and second chambers,
the vacuum barriers being arranged in at least one tubular portion
that connects the first and second chambers; [0013] the device
comprises, around the pipes passing from the third to the second
chamber, vacuum barriers which separate the volumes selectively
under vacuum of the third and second chambers, the vacuum barriers
being arranged in at least one tubular portion that connects the
third and second chambers; [0014] the cold head of the
cryocooler(s) is associated with a heat exchanger that acts as a
condenser for the working fluid; [0015] the cold head of the main
cryocooler is connected to the reservoir via two pipes the upstream
ends of which are connected to a hermetic volume arranged under the
cold head of the main cryocooler, the downstream ends of the pipes
being connected to an upper end of the reservoir via a vertical or
substantially vertical portion; [0016] the cold head of the
secondary cryocooler is connected to the reservoir via two pipes
the upstream ends of which are connected to a hermetic volume
arranged under the cold head of the secondary cryocooler and the
downstream ends of which are connected to an upper end of the
reservoir via a vertical or substantially vertical portion; [0017]
in the operating configuration, out of: the main cryocooler and the
secondary cryocooler, at least one is arranged in a vertical
configuration, [0018] the vacuum barriers comprise for example at
least one of the following members: a system referred to as a
"simple cone" system, a system referred to as a "double cone"
system, [0019] a heater, for example an electric heater, is mounted
on at least one heat exchanger of a cold head of a cryocooler,
[0020] the chamber or chambers are placed under vacuum with respect
to air at a pressure of between 10.sup.-3 and 10.sup.-6 mbar,
[0021] the member that is to be cooled comprises a coil or electric
cables which are superconductors, [0022] the device comprises
several secondary cryocoolers, [0023] the secondary cryocooler or
one of the secondary cryocoolers is in operation and contributes to
the cooling of the member at the same time as the main cryocooler,
[0024] the working fluid comprises or is made up of at least one
out of: helium, hydrogen, neon, nitrogen, argon, oxygen, methane,
krypton, xenon, CnHm, ammonium, a CFC, an HCFC, an HFC or any other
fluid refrigerant, [0025] the fluid loop may use a buffer volume to
limit the rise in pressure of the loop when the system is at
ambient temperature.
[0026] The invention also relates to a method for cooling a member
to a low temperature using a cryogenic cooling device having any
one of the features above or below, in which the main cryocooler is
used to cool the member, the first chamber and the second chamber
being placed under vacuum, the secondary cryocooler being
selectively switched off or on while the main cryocooler is in
operation.
[0027] Moreover, some embodiments of the invention may comprise one
or more of the following features: [0028] the main cryocooler is
switched off and, at the same time as or in anticipation of this,
the secondary cryocooler is started in order to cool the member,
the third chamber being placed under vacuum or kept under vacuum,
[0029] when a cryocooler is switched off, the cold head of the
cryocooler switched off is heated up to an ambient temperature
using at least one of the following steps: by spontaneous natural
heating, by commanded active heating, by forced circulation of gas
at ambient temperature into the chamber of the cryocooler or around
the exchangers via a coiled tube or any other device, by bringing
the volume of the cryocooler chamber to atmospheric pressure,
[0030] the method comprises a step of repairing or maintaining one
of the two cryocoolers while the other cryocooler is in operation
and is cooling the member, the method comprising: [0031] shutting
down the cryocooler intended to undergo repair or maintenance or
keeping it in the switched off state, [0032] keeping the cryocooler
intended to undergo repair or maintenance at ambient temperature or
bringing it to ambient temperature, [0033] opening the chamber
containing the cryocooler intended to undergo repair or
maintenance, [0034] dismantling the cryocooler intended to undergo
repair or maintenance so that it can be replaced or repaired
without connected the hermetic volume to the atmosphere, [0035]
maintaining the vacuum within the chamber of the other cryocooler
that is in operation and in the second chamber.
[0036] The invention may also relate to any alternative device or
method comprising any combination of the features above or
below.
[0037] Other particulars and advantages will become apparent on
reading the following description, given with reference to the
single FIGURE which is a schematic and partial view in cross
section illustrating the structure and operation of a refrigeration
device according to one possible embodiment of the invention.
[0038] With reference to the FIGURE, the cryogenic cooling device
comprises a main cryocooler 18 comprising, in the conventional way,
a cold head 19. The main cryocooler 18 (and in particular the cold
head 19) is arranged in a first chamber 16 selectively placed under
vacuum. The cold head 19 is equipped for example with a heat
exchanger 17 to liquefy a working fluid. The exchanger 17 is, for
example, screwed to the base of the cold head 19 using screws
20.
[0039] Underneath the cold head 19 and the exchanger 17, the main
cryocooler 18 delimits a volume 21 for the liquefied working fluid,
this volume being connected via two pipes, respectively an upper
pipe 31 and a lower pipe 30, to a storage reservoir 9 for the
liquefied working fluid.
[0040] This liquefied working fluid storage reservoir 9 contains
the member 8 that is to be cooled by (direct or indirect) exchange
of heat with the liquefied working fluid.
[0041] The storage reservoir 9 is housed in a second chamber 10
selectively placed under vacuum independently of the first chamber
16. What that means is that the pipes 30, 31 pass from the first 16
to the second 10 chamber through tubular portions 23 that connect
the first 16 and second 10 chambers.
[0042] The second chamber 10 rests, for example, on the ground via
a base and is, for example, sealed off at the top by a removable
cover 11 (removable for example using screws 14).
[0043] The vacuums within the volumes of the first 16 and second 10
chambers are kept independent for example via one or more vacuum
barriers 40 arranged respectively around the pipes 30, 31 inside
the tubular connecting portions 23.
[0044] The vacuum barriers 40 may comprise any known system such as
a double cone.
[0045] According to one advantageous feature, the device comprises
a secondary cryocooler 1, for example of the same type as the main
cryocooler 18. The secondary cryocooler 1 comprises a structure
equivalent to the structure described hereinabove. What that means
to say is that the cold head 7 of the secondary cryocooler 1 is
arranged in a third chamber 4 selectively placed under vacuum. As
before, the cold head 7 is equipped with a heat exchanger 2 for
liquefying a working fluid. The exchanger 2 is screwed to the base
of the cold head 7 using screws 5.
[0046] Underneath the cold head 7 and the exchanger, the secondary
cryocooler 1 delimits a volume 121 for the liquefied working fluid,
this volume 121 being connected by two pipes, respectively an upper
pipe 131 and a lower pipe 130, to the same liquefied working fluid
storage reservoir 9.
[0047] As before, the second chamber 10 is selectively placed under
vacuum independently of the third chamber 4. The pipes 130, 131
pass from the third 4 to the second 10 chamber through the tubular
portions 23 that connect the third 4 and second 10 chambers.
[0048] The vacuums within the volumes of the third 4 and second 10
chambers are kept independent via one or more vacuum barriers 40
arranged respectively around the pipes 130, 131, inside the tubular
connecting portions 23.
[0049] In this way, the chambers 16, 10 and 4 are isolated from one
another by vacuum barriers 40 so that the various chambers can be
placed under vacuum independently of one another.
[0050] Where the working fluid is nitrogen, the device can be used
to keep the member 8 at a cryogenic temperature (for example of 100
K).
[0051] The member 8 to be kept at a cryogenic temperature may, for
example, be a superconductor coil, a heat exchanger in a heat
exchange relationship with another heat-transfer fluid, or any
other suitable member.
[0052] In one possible operation, the member 8 that is to be cooled
is immersed in a bath of liquid nitrogen at a temperature of 100K
for example.
[0053] The heat generated by the member 8 evaporates some of the
liquid nitrogen from the bath 9. This gaseous nitrogen travels
upward via the upper pipe 31 of the main cryocooler 18. On arriving
at the exchanger 17 of the main cryocooler 18, the gaseous nitrogen
is liquefied once again.
[0054] To do this, the exchanger 17 is kept at a temperature
slightly below 100K by the cryocooler 18 which is in operation. The
cold head 19 of the main cryocooler 18 extracts heat from the
adjacent exchanger 17. The liquid nitrogen drops under gravity into
the volume 21 situated under the exchanger 17 and then travels
downward via the lower pipe 30 as far as the bath in the reservoir
9. This process takes place continuously in a working loop for the
working fluid (nitrogen in this example).
[0055] A heater, for example an electric heater (not depicted) may
be mounted on the heat exchanger 17 of the cold head 19 of the main
cryocooler 18 to regulate the temperature thereof.
[0056] The secondary cryocooler 1 preferably has a structure and an
operation identical to those of the main cryocooler 18.
[0057] The secondary cryocooler 1 is preferably used as a reserve.
When the main cryocooler 18 is in operation, the secondary
cryocooler 1 is switched off and the temperature of its cold head 7
is close to ambient temperature. The working fluid contained in the
exchanger 2, the pipes 130, 131 is in the gaseous state.
[0058] As a result of thermal stratification, the gas in the pipes
130, 131 forms gaseous thermal plugs which limit transfers of heat
between the secondary cryocooler 1 which is switched off and the
reservoir 9.
[0059] By contrast, should the main cryocooler 18 fail or be
switched off (for example for the purposes of carrying out
maintenance on the main cryocooler 18), the secondary cryocooler 1
can be switched on, for example automatically.
[0060] After the main cryocooler 18 has been shut down, its cold
head 19 and its exchanger 17 are warmed up to ambient temperature.
This warming can be done either by waiting for them to warm up
naturally, or by using an electric heater or by circulation of gas
at ambient temperature, or by making the pressure in the first
chamber 16 rise to atmospheric pressure.
[0061] The pressure in the first chamber 16 can be raised from the
vacuum up to atmospheric pressure for example using a valve (not
depicted) allowing selective communication between the interior
volume of the chamber 16 and the exterior atmosphere.
[0062] The first 16 and the third 4 chambers are sealed off by at
least one insulating and selectively removable cap 15 allowing
direct access to the cryocooler, notably the cold head thereof.
[0063] For example, the first 16 and third 4 chambers are
mechanically connected to the second chamber 10 and are raised up
above the ground.
[0064] The removable cap 15 is, for example, positioned on the
bottom part of each first 16 and third 4 chamber, so that it is
adjacent to the cold head 19, 7.
[0065] Each cap 15 is, for example, mounted on the body of its
chamber 16, 4 via fixing screws 22 or any other suitable
system.
[0066] Thus, to gain access to the main cryocooler 18, the cap 15
is removed. The operator can then dismantle the exchanger 17, for
example by removing the fixing screws 20 on the cold head 19. The
flange 12 of the cryocooler 18 can then be disconnected from the
chamber 16 (for example by removing the fixing screws 13). The
cryocooler can then be taken out for replacement or maintenance
thereof.
[0067] A new cryocooler or the repaired cryocooler can then be
refitted. The flange 12 is once again fixed to the chamber 16. The
fixing screws 20 which attach the exchanger 17 to the cold head 19
are refitted. The cap 15 is also put back into position.
[0068] A vacuum is once more created in the first chamber 16, for
example by means of a vacuum pump and via a valve (neither of these
has been depicted).
[0069] The repaired or exchanged main cryocooler 18 can then be
switched on if the secondary cryocooler 1, which has now taken over
the production of cold, malfunctions or requires maintenance.
[0070] The procedure for replacing or performing maintenance on the
other cryocooler may be identical to the procedure described
hereinabove.
[0071] The cryocoolers may for example operate on a Gifford
MacMahon cycle. The cryocoolers 1, 18 can be insulated using a
superinsulator of the multilayer or monolayer type.
* * * * *