U.S. patent application number 10/573903 was filed with the patent office on 2007-01-04 for device and method for cryogenically seperating a gas mixture.
Invention is credited to Jean-Pierre Tranier.
Application Number | 20070000282 10/573903 |
Document ID | / |
Family ID | 34307552 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070000282 |
Kind Code |
A1 |
Tranier; Jean-Pierre |
January 4, 2007 |
Device and method for cryogenically seperating a gas mixture
Abstract
The invention relates to a device for separating gas by means of
cryogenic distillation, comprising a system of columns (13, 15),
means for sending gas which is to be separated to a column
belonging to said column system, means for drawing off at least one
product (31,35) of the column system and means for sending gas from
the device (23) into a turbine (11) with bearings wherein the
bearings of said turbine are antifriction bearings.
Inventors: |
Tranier; Jean-Pierre;
(L'Hay-Les-Roses, FR) |
Correspondence
Address: |
AIR LIQUIDE
2700 POST OAK BOULEVARD, SUITE 1800
HOUSTON
TX
77056
US
|
Family ID: |
34307552 |
Appl. No.: |
10/573903 |
Filed: |
September 21, 2004 |
PCT Filed: |
September 21, 2004 |
PCT NO: |
PCT/FR04/50450 |
371 Date: |
March 29, 2006 |
Current U.S.
Class: |
62/621 ;
62/645 |
Current CPC
Class: |
F25J 2240/02 20130101;
F01D 25/16 20130101; F01D 25/22 20130101; F05D 2240/51 20130101;
F25J 2290/42 20130101; F25J 3/0295 20130101; F25J 3/04866
20130101 |
Class at
Publication: |
062/621 ;
062/645 |
International
Class: |
F25J 3/00 20060101
F25J003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2003 |
FR |
0350630 |
Claims
1-12. (canceled)
13: A unit for separating gas by cryogenic distillation, comprising
a system of columns, means for sending a gas to be separated to one
column of the column system, means for withdrawing at least one
product from the column system, means for sending a gas of the
unit, possibly at least one portion of the gas mixture to be
separated, into a turbine with bearings, and means for sending at
least one portion of the gas expanded in the turbine to one column
of the column system if the expanded gas constitutes at least one
portion of the gas mixture to be separated, characterized in that
the bearings of the turbine are rolling bearings.
14: The unit as claimed in claim 13, in which the turbine has
unoiled bearings.
15: The unit as claimed in claim 14, in which the turbine has
unlubricated bearings.
16: The unit as claimed in claim 13, in which the gas to be
separated contains oxygen and/or nitrogen and/or hydrogen and/or
methane and/or carbon monoxide as main components.
17: The unit as claimed in claim 16, in which the expanded gas is
air, nitrogen or hydrogen.
18: The unit as claimed in claim 13, in which the turbine is
installed at least one meter above the floor, preferably at least
two meters above the floor or even at least five meters above the
floor.
19: The unit as claimed in claim 13, in which the turbine is braked
by a brake booster, possibly of the centrifugal type, placed on the
same shaft as the turbine, all the bearings of this common shaft
being unlubricated.
20: The unit as claimed in claim 19, in which all the bearings of
the common shaft are of the rolling bearing type.
21: The unit as claimed in claim 13, in which the turbine is braked
by a brake generator whose bearings are unlubricated.
22: The unit as claimed in claim 21, in which the bearings of the
brake generator are of the magnetic type.
23: A method of separating a gas mixture by cryogenic distillation,
in which a gas mixture to be separated is sent to a column of a
column system, at least one product is withdrawn from the column
system, at least one portion of a gas of the unit, possibly at
least one portion of the gas mixture to be separated, is sent into
a turbine with bearings, characterized in that the bearings of the
turbine are rolling bearings.
24: The method as claimed in claim 23, in which the turbine is
braked by a brake generator whose bearings are unlubricated and the
brake generator is driven at the same speed as the turbine.
Description
[0001] The present invention relates to a unit and to a method of
separating a gas mixture by cryogenic distillation.
[0002] For a very long time, as described in "Cryogenic
Engineering" by Hausen and Linde, pp. 457-461, air gas separation
units use turbines with lubricated bearings, these bearings being
axial or radial. To produce refrigeration, the turbines expand air
or nitrogen with the production of external work, the expansion
being of the isotropic type apart from irreversibilities.
[0003] However, turbines with lubricated bearings, for example
those lubricated with oil, have two major drawbacks.
[0004] Firstly, there is a risk of the process gas being
contaminated with oil should the sealing system along the shaft
fail. Such a contamination results in oil migrating into the
various items of equipment of the unit (exchangers, pipes,
distillation columns, reboiler), the oil possibly tending to
concentrate near the main reboiler in the presence of relatively
pure oxygen. This could be the cause of a major explosion in the
air gas separation unit.
[0005] Secondly, it is thus necessary for economic reasons to
install the turbine close to the floor in order to minimize the
distances from the oil tank; this constraint is not specific to air
gas separation plants but may also apply to gas (H.sub.2, He,
CH.sub.4, etc.) liquifiers or to other gas separation (H.sub.2/CO,
etc.) units.
[0006] The object of the invention is to dispense with lubricated
bearings for the expansion turbines of units for separating gas
mixtures by cryogenic distillation by expanding the gas mixture to
be separated in a turbine on bearings (steel or ceramic ball
bearings or roller bearings), these bearings possibly being
periodically greased but not being oiled.
[0007] One subject of the invention is a unit for separating gas by
cryogenic distillation, comprising a system of columns, means for
sending a gas to be separated to one column of the column system,
means for withdrawing at least one product from the column system,
means for sending a gas of the unit, possibly at least one portion
of the gas mixture to be separated, into a turbine with bearings,
and means for sending at least one portion of the gas expanded in
the turbine to one column of the column system if the expanded gas
constitutes at least one portion of the gas mixture to be
separated, characterized in that the bearings of the turbine are
rolling bearings.
[0008] Optionally: [0009] the turbine has unoiled bearings; [0010]
the turbine has unlubricated bearings; [0011] the gas to be
separated contains oxygen and/or nitrogen and/or hydrogen and/or
methane and/or carbon monoxide as main components; [0012] the
expanded gas is air, nitrogen or hydrogen, [0013] the turbine is
installed at least one meter above the floor, preferably at least
two meters above the floor or even at least five meters above the
floor; [0014] the turbine is braked by a brake booster, possibly of
the centrifugal type, placed on the same shaft as the turbine, all
the bearings of this common shaft being unlubricated; [0015] all
the bearings of the common shaft are of the rolling bearing type;
[0016] the turbine is braked by a brake generator whose bearings
are unlubricated; and
[0017] the bearings of the brake generator are of the magnetic
type.
[0018] Another subject of the invention is a method of separating a
gas mixture by cryogenic distillation, in which a gas mixture to be
separated is sent to a column of a column system, at least one
product is withdrawn from the column system, at least one portion
of a gas of the unit, possibly at least one portion of the gas
mixture to be separated, is sent into a turbine with bearings,
characterized in that the bearings of the turbine are rolling
bearings.
[0019] Preferably, the turbine is braked by a brake generator whose
bearings are unlubricated and the brake generator is driven at the
same speed as the turbine.
[0020] The invention will be described in greater detail with
reference to the figures, which show air separation units according
to the invention.
[0021] FIG. 1 shows a cryogenic distillation air separation unit in
which: [0022] an air stream 1 is compressed to the medium pressure
in a compressor 3 and is then purified in a purification unit 5,
which may be of any known type. The air is then divided into two
fractions 21, 23. The fraction 21 is cooled on flowing through the
exchange line 7 and is sent to the bottom of the medium-pressure
column 13 in gaseous form; [0023] the remainder of the air 23 is
boosted in a booster 9, cooled in a chiller 19 and sent to the
exchange line 7 where it is partially cooled before being sent to
the blowing turbine 11. This turbine may be a turbine on bearings
(steel or ceramic ball or roller bearings); [0024] the turbine 11
is mounted at least one meter above the floor, preferably at least
two meters above the floor or even at least five meters above the
floor; [0025] the turbine 11 is on the same shaft as the booster 9.
The booster 9 is preferably of the centrifugal type, having
unlubricated bearings.
[0026] Preferably, all the bearings of the shaft are rolling
bearings; [0027] alternatively, the booster may be replaced with a
generator, again with unlubricated bearings; [0028] the air
expanded in the turbine 11 is sent into a low-pressure column 15
with a minaret; [0029] a rich-liquid stream 25, a lower lean-liquid
stream 27 and an upper lean-liquid stream 29 are sent from the
medium-pressure column 13 to the low-pressure column 15. A purge
stream is withdrawn from the condenser-reboiler 17 that connects
the two columns; and
[0030] pure nitrogen 31 is withdrawn from the top of the minaret,
waste nitrogen 33 is withdrawn from the bottom of the minaret and
gaseous oxygen 35 is withdrawn from the bottom of the low-pressure
column. These three streams are warmed in the exchange line 7. Part
of the waste nitrogen is used for regeneration after a warming
step.
[0031] FIG. 2 shows a cryogenic distillation air separation unit
with an air cycle, in which: [0032] an air stream 1 is compressed
to the medium-pressure in a compressor 3 and then purified in a
purification unit 5, which may be of any known type. The air is
boosted in a booster 9, cooled in a cooler (not shown) and sent to
the exchange line 7 where it is partially cooled before being sent
in part to a Claude turbine 11. This turbine is a turbine on
bearings (steel or ceramic ball or roller bearings); [0033] the
turbine 11 is mounted at least one meter above the floor,
preferably at least two meters above the floor or even at least
five meters above the floor; [0034] the turbine 11 may be coupled
to the booster 9; [0035] the air expanded in the turbine 11 is
partly sent to the medium-pressure column 13 and partly recycled
(stream 43) to the booster 9. In the variant embodiment with no
cycle, all the air expanded in the turbine 11 is sent to the
medium-pressure column; [0036] a rich-liquid stream 25, a lower
lean-liquid stream 27 and an upper lean-liquid stream 29 are sent
from the medium-pressure column 13 to the low-pressure column 15. A
purge stream is withdrawn from the condenser-reboiler 17 connecting
the two columns; [0037] pure nitrogen 31 is withdrawn from the top
of the minaret, waste nitrogen 33 is withdrawn from the bottom of
the minaret and gaseous oxygen 35 is withdrawn from the bottom of
the low-pressure column. These three streams are warmed in the
exchange line 7. Part of the waste nitrogen serves for regeneration
after a warming step; and [0038] the unit produces liquid nitrogen
39 at the top of the medium-pressure column and liquid oxygen 41 at
the bottom of the low-pressure column.
[0039] FIG. 3 shows a cryogenic distillation air separation unit in
which: [0040] an air stream 1 is compressed to the medium-pressure
in a compressor 3 and then purified in a purification unit 5, which
may be of any known type. The air is cooled on flowing through the
exchange line 7 and is sent to the bottom of the medium-pressure
column 13 in gaseous form; [0041] a rich-liquid stream 25, a lower
lean-liquid stream 27 and an upper lean-liquid stream 29 are sent
from the medium-pressure column 13 to the low-pressure column 15. A
purge stream is withdrawn from the condenser-reboiler 17 that
connects the two columns; and [0042] pure nitrogen 31 is withdrawn
from the top of the minaret, waste nitrogen 33 is withdrawn from
the bottom of the minaret and gaseous oxygen 35 is withdrawn from
the bottom of the low-pressure column. These three streams are
warmed in the exchange line 7. Part of the waste nitrogen is used
for regeneration after a warming step; [0043] medium-pressure
nitrogen 45 is partly warmed in the exchange line before being
expanded in the turbine 11. This turbine is a turbine on bearings
(steel or ceramic ball or roller bearings). The turbine 11 is
mounted at least one meter above the floor, preferably at least two
meters or even at least five meters above the floor. The expanded
nitrogen is mixed with the waste nitrogen 33; and [0044]
alternatively, if the low-pressure column 15 operates at a
sufficiently high pressure, it is possible to expand a stream of
low-pressure nitrogen in the turbine.
[0045] It will be readily understood that the units in question may
comprise any possible combination of Claude turbines, blowing
turbines and nitrogen turbines, provided that at least one of these
turbines is a turbine on bearings (steel or ceramic ball or roller
bearings).
[0046] The invention is obviously not limited to processes using a
column with a minaret. It applies to any type of air separation
method using an expansion turbine, including pumped methods.
* * * * *