U.S. patent application number 13/687645 was filed with the patent office on 2014-05-29 for optimized heat exchange in a co2 de-sublimation process.
This patent application is currently assigned to L'Air Liquide Societe Anonyme Pour l'Etude et l'Expoitation des Procedes Georges Claude. The applicant listed for this patent is L'AIR LIQUIDE SOCIETE ANONYME POUR L'ETUDE ET L'EX. Invention is credited to Christopher Hoeger, Paul Terrien, Pascal Tessier.
Application Number | 20140144178 13/687645 |
Document ID | / |
Family ID | 50772078 |
Filed Date | 2014-05-29 |
United States Patent
Application |
20140144178 |
Kind Code |
A1 |
Terrien; Paul ; et
al. |
May 29, 2014 |
OPTIMIZED HEAT EXCHANGE IN A CO2 DE-SUBLIMATION PROCESS
Abstract
The present invention is a process for removing carbon dioxide
from a compressed gas stream including cooling the compressed gas
in a first heat exchanger, introducing the cooled gas into a
de-sublimating heat exchanger, thereby producing a first solid
carbon dioxide stream and a first carbon dioxide poor gas stream,
expanding the carbon dioxide poor gas stream, thereby producing a
second solid carbon dioxide stream and a second carbon dioxide poor
gas stream, combining the first solid carbon dioxide stream and the
second solid carbon dioxide stream, thereby producing a combined
solid carbon dioxide stream, and indirectly exchanging heat between
the combined solid carbon dioxide stream and the compressed gas in
the first heat exchanger.
Inventors: |
Terrien; Paul; (Baltimore,
MD) ; Tessier; Pascal; (Wilmington, DE) ;
Hoeger; Christopher; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
L'AIR LIQUIDE SOCIETE ANONYME POUR L'ETUDE ET L'EX |
Paris |
|
FR |
|
|
Assignee: |
L'Air Liquide Societe Anonyme Pour
l'Etude et l'Expoitation des Procedes Georges Claude
Paris
FR
|
Family ID: |
50772078 |
Appl. No.: |
13/687645 |
Filed: |
November 28, 2012 |
Current U.S.
Class: |
62/617 |
Current CPC
Class: |
B01D 2259/65 20130101;
F25J 2280/40 20130101; F25J 2270/90 20130101; F25J 2240/02
20130101; B01D 53/002 20130101; Y02C 20/40 20200801; F25J 3/067
20130101; F25J 2220/82 20130101; F25J 2290/12 20130101; F25J
2205/20 20130101; Y02C 10/12 20130101; B01D 2257/504 20130101; F25J
2270/12 20130101; F25J 2210/70 20130101; B01D 2258/0283
20130101 |
Class at
Publication: |
62/617 |
International
Class: |
F25J 3/06 20060101
F25J003/06 |
Claims
1. A process for removing carbon dioxide from a compressed gas
stream comprising: a) cooling the compressed gas (101) in a first
heat exchanger (102), b) introducing the cooled gas (103) into a
de-sublimating heat exchanger (104), thereby producing a first
solid carbon dioxide stream (113) and a first carbon dioxide poor
gas stream (105), c) expanding the carbon dioxide poor gas stream,
thereby producing a second solid carbon dioxide stream (109) and a
second carbon dioxide poor gas stream (110), d) combining the first
solid carbon dioxide stream and the second solid carbon dioxide
stream, thereby producing a combined solid carbon dioxide stream
(114), and e) indirectly exchanging heat between the combined solid
carbon dioxide stream and the compressed gas in the first heat
exchanger.
2. The process of claim 1, wherein the compressed gas is flue
gas.
3. The process of claim 1, wherein the compressed gas is cooled to
a temperature higher than the carbon dioxide de-sublimation
temperature.
4. The process of claim 1, wherein the second carbon dioxide poor
gas stream (110) is introduced into the de-sublimating heat
exchanger (104) to indirectly exchange heat with the cooled gas
(103).
5. The process of claim 1, wherein after the second carbon dioxide
poor gas stream exits the de-sublimating heat exchanger, it (111)
is introduced into the first heat exchanger (102) to indirectly
exchange heat with the compressed gas (101).
6. The process of claim 1, further comprising introducing the
combined solid carbon dioxide stream (114) into a second heat
exchanger (117), after step d) and before step e), wherein the
combined solid carbon dioxide stream indirectly exchanges heat with
an external refrigeration loop (123).
7. The process of claim 6, wherein the external refrigeration loop
comprises: vaporizing a compressed refrigeration stream (125/127)
in the de-sublimating heat exchanger (104), thereby producing a
warmed refrigeration stream (129/130/120), compressing the warmed
refrigeration fluid (120), thereby producing a compressed
refrigeration stream (122), and condensing the compressed
refrigeration stream in a second heat exchanger (117) by indirectly
transferring heat with the combined solid carbon dioxide stream
(114/116), thereby producing a cooled refrigeration stream
(124).
8. The process of claim 6, wherein the compressed refrigeration
stream (122) is further warmed (123) in the first heat exchanger
(102) before indirectly transferring heat with the combined solid
carbon dioxide stream.
9. The process of claim 6, wherein the cooled refrigeration stream
(124) is further cooled (125) in the first heat exchanger (102),
before being compressed.
Description
BACKGROUND
[0001] Carbon dioxide emissions from fossil fuel combustion is a
growing source of concern, and various technologies have been, and
continue to be developed, for capturing CO2 from flue gas and other
gas streams. Major technologies include amine wash, physical
adsorption technologies, cryogenic technologies (CO2 liquefaction).
These technologies involve significant additional investment and
operating costs for industrial plants. In the case of coal power
plants for example, a resulting increase of the cost of electricity
in the range of 4 to 5 US cents/kWh is expected. One of the main
challenges today is to reduce cost of carbon dioxide capture from
flue gas through efficiency improvement and capital reduction.
[0002] There are major drawbacks to all the existing systems. One
possible alternative to traditional capture solutions is called
anti-sublimation. The basic concept is to separate CO2 from a flue
gas by cooling the flue gas to turn the CO2 into solid
(de-sublimation or cryo-condensation of CO2). Indeed, at such low
CO2 partial pressure (<5.11 atmosphere), the CO2 will be
directly changed from gas phase to solid phase. There are two main
schemes to implement such a process. The first is de-sublimation at
atmospheric or very low pressure. For this scheme, a significant
external refrigeration loop is required to perform such a cooling.
This is known as indirect de-sublimation. The second is
de-sublimation at higher pressure by expansion with solid
formation. This is known as direct de-sublimation.
[0003] However, in any case, the efficiency of the process is
strongly related to the ability to integrate the heat exchange.
This is to say that without heat exchangers to recover energy from
the flue gas notably, the efficiency of the process would be
drastically decreased. Hence, there is a need in the industry for
an optimized heat exchange in a carbon dioxide de-sublimation
process.
SUMMARY
[0004] The present invention is a process for removing carbon
dioxide from a compressed gas stream including cooling the
compressed gas in a first heat exchanger, introducing the cooled
gas into a de-sublimating heat exchanger, thereby producing a first
solid carbon dioxide stream and a first carbon dioxide poor gas
stream, expanding the carbon dioxide poor gas stream, thereby
producing a second solid carbon dioxide stream and a second carbon
dioxide poor gas stream, combining the first solid carbon dioxide
stream and the second solid carbon dioxide stream, thereby
producing a combined solid carbon dioxide stream, and indirectly
exchanging heat between the combined solid carbon dioxide stream
and the compressed gas in the first heat exchanger.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0005] Illustrative embodiments of the invention are described
below. While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof have been shown
by way of example in the drawings and are herein described in
detail. It should be understood, however, that the description
herein of specific embodiments is not intended to limit the
invention to the particular forms disclosed, but on the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the invention
as defined by the appended claims.
[0006] It will of course be appreciated that in the development of
any such actual embodiment, numerous implementation-specific
decisions must be made to achieve the developer's specific goals,
such as compliance with system-related and business-related
constraints, which will vary from one implementation to another.
Moreover, it will be appreciated that such a development effort
might be complex and time-consuming, but would nevertheless be a
routine undertaking for those of ordinary skill in the art having
the benefit of this disclosure.
[0007] This invention relates to a specific process embodiment
where the heat exchange is optimized in order to maximize
efficiency in a realistic and cost-effective way.
[0008] The compressed flue gas stream 101 is first cooled down to
above frosting point temperature in a multi-fluid heat exchanger
102 which may be a brazed aluminium heat exchanger (such as is a
typical cryogenic heat exchanger used in Air Separation Units).
[0009] After multi-fluid heat exchanger 102, the refrigerated flue
gas 103 is sent to a de-sublimating heat exchanger 104 where part
of the CO2 is de-sublimated 113.
[0010] After the de-sublimating heat exchanger 104, the partially
CO2 depleted flue gas 105 is sent to an expansion turbine 106 where
it is expanded to almost atmospheric pressure 107 and the remainder
of the CO2 to be captured is recovered as solids 109 in solids
separator 108, (i.e., achieving 90% capture of the incoming CO2
flow rate when streams 113 and 109 are combined).
[0011] The solid CO2 streams 113 and 109 are mixed together 114 and
pumped to a high pressure 116 in solids pressurizer 115. This
pressure should be high enough to not vaporize at ambient
temperature. Then the high pressure CO2 stream 116 is sent to a
melting heat exchanger 117 where most of the sensible heat plus the
latent heat of fusion is recovered by the condensing refrigerant
123. The liquefied CO2 118 is then sent to the multi-fluid heat
exchanger 102 to recover the sensible heat of the liquid, after
which the warmed fluid 119 exits the system. The 002-depleted cold
gas 110 is sent to the de-sublimating heat exchanger 104 and then
to the multi-fluid heat exchanger 102 to recover all the cold. It
is then pumped to the final pressure (not shown).
[0012] A small refrigeration loop is required in this
configuration. The refrigerant cycle is an inversed rankine cycle,
the condensation happens in the melting heat exchanger 117, close
to CO2 triple point temperature, and vaporization happens in the
de-sublimating heat exchanger 104, below the outlet temperature of
the de-sublimating heat exchanger. However, all other heat recovery
involved will happen in the multi-fluid heat exchanger 102.
[0013] The following points are important in order to achieve a
high efficiency. There needs to be partial de-sublimation of the
flue gas prior to the turbine, thus allowing less temperature
difference between the inlet and the outlet of the turbine. This
also allows the pressure required for the flue gas to be as low as
approximately 6 bar absolute. There needs to be an inversed rankine
cycle of the refrigerant with condensation happening at CO2 melting
temperature There needs to be heat recovery of all fluids not
involving solid CO2 in the multi-fluid heat exchanger (aluminium
brazed in particular). The heat integration between flue gas lines,
CO2 lines and refrigerant lines allows lowering the average
temperature difference. Furthermore, a very low temperature
approach (down to 2 C or below) would be achievable whereas
typically 5 C is a reasonable limit in other types of heat
exchanger.
A BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a schematic representation of one embodiment of
the present invention.
* * * * *