U.S. patent application number 13/531862 was filed with the patent office on 2013-09-12 for apparatus and method for recovering energy after carbon dioxide capture.
This patent application is currently assigned to KIA MOTORS CORPORATION. The applicant listed for this patent is Sung Yeup CHUNG, Ki Chun LEE, Sang Jin PARK. Invention is credited to Sung Yeup CHUNG, Ki Chun LEE, Sang Jin PARK.
Application Number | 20130234438 13/531862 |
Document ID | / |
Family ID | 49113417 |
Filed Date | 2013-09-12 |
United States Patent
Application |
20130234438 |
Kind Code |
A1 |
PARK; Sang Jin ; et
al. |
September 12, 2013 |
APPARATUS AND METHOD FOR RECOVERING ENERGY AFTER CARBON DIOXIDE
CAPTURE
Abstract
Disclosed are an apparatus and a method for recovering energy
after carbon dioxide capture. The apparatus includes an energy
recovery unit at a discharge part of a carbon dioxide capturing
apparatus through which captured carbon dioxide is discharged. The
energy recovery unit reduces a discharge pressure of the carbon
dioxide to a pressure level suitable for a fixation or conversion
treatment, and simultaneously generates and recovers energy
generated during the pressure reduction.
Inventors: |
PARK; Sang Jin; (Uiwang,
KR) ; LEE; Ki Chun; (Seoul, KR) ; CHUNG; Sung
Yeup; (Seoul, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PARK; Sang Jin
LEE; Ki Chun
CHUNG; Sung Yeup |
Uiwang
Seoul
Seoul |
|
KR
KR
KR |
|
|
Assignee: |
KIA MOTORS CORPORATION
Seoul
KR
HYUNDAI MOTOR COMPANY
Seoul
KR
|
Family ID: |
49113417 |
Appl. No.: |
13/531862 |
Filed: |
June 25, 2012 |
Current U.S.
Class: |
290/52 ; 415/1;
415/182.1 |
Current CPC
Class: |
B01D 53/92 20130101;
Y02C 10/04 20130101; B01D 2257/504 20130101; B01D 53/343 20130101;
Y02C 10/08 20130101; Y02C 20/40 20200801; B01D 2258/01 20130101;
B01D 53/62 20130101 |
Class at
Publication: |
290/52 ;
415/182.1; 415/1 |
International
Class: |
F01D 1/02 20060101
F01D001/02; F01D 15/10 20060101 F01D015/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 9, 2012 |
KR |
10-2012-0024182 |
Claims
1. An apparatus for recovering energy after carbon dioxide capture,
comprising an energy recovery unit at a discharge part of a carbon
dioxide capturing apparatus, the discharge part configured for
discharging captured carbon dioxide, wherein the energy recovery
unit reduces a discharge pressure of the carbon dioxide and
simultaneously recovers energy generated during the pressure
reduction.
2. The apparatus of claim 1, wherein the discharge pressure is
reduced to a pressure suitable for a fixation or conversion
treatment of the captured carbon dioxide.
3. The apparatus of claim 1, wherein the energy recovery unit is
connected to one or more process operating units of the carbon
dioxide capturing apparatus and is configured and arranged to
supply the recovered energy to one or more of the process operating
units.
4. The apparatus of claim 1, wherein the apparatus further
comprises a condenser at the discharge part, and the energy
recovery unit comprises: a turbine disposed at an outlet of the
condenser; and a generator connected to the turbine.
5. A method for recovering energy after carbon dioxide capture,
comprising: capturing, by a carbon dioxide capturing apparatus,
carbon dioxide from an exhaust gas; discharging, by the carbon
dioxide capturing apparatus, the captured carbon dioxide, the
discharged carbon dioxide having a discharge pressure; reducing the
discharge pressure of the discharged carbon dioxide to a pressure
level suitable for a fixation or conversion treatment; and
recovering energy generated during the pressure reduction.
6. The method of claim 5, further comprising supplying the
recovered energy to one or more process operating units of the
carbon dioxide capturing apparatus.
7. The method of claim 5, wherein the step of recovering energy
comprises: flowing discharged carbon dioxide through a turbine,
thereby rotating the turbine with the discharge pressure of the
discharged carbon dioxide to create a rotary force; reducing the
pressure of the carbon dioxide that has flowed through the turbine
to a reduced pressure level suitable for the fixation or conversion
treatment; and delivering the rotary force of the turbine to a
generator connected to the turbine and allowing generation of
energy in the generator.
8. The method of claim 7, wherein when the discharge pressure of
the carbon dioxide captured by the carbon dioxide capturing
apparatus ranges from about 1.8 atm to about 6 atm, the reduced
pressure of the carbon dioxide is less than about 1.8 atm.
9. The method of claim 8, wherein the reduced pressure of the
carbon dioxide is less than about 1.6 atm.
10. The method of claim 8, wherein the reduced pressure of the
carbon dioxide is less than about 1.4 atm.
11. The method of claim 8, wherein the reduced pressure of the
carbon dioxide is about 1.2 atm.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims under 35 U.S.C. .sctn.119(a) the
benefit of Korean Patent Application No. 10-2012-0024182 filed Mar.
9, 2012, the entire contents of which are incorporated herein by
reference.
BACKGROUND
[0002] (a) Technical Field
[0003] The present invention relates to an apparatus and method for
recovering energy after carbon dioxide capture. More particularly,
it relates to an apparatus and method for recovering energy after
carbon dioxide capture, which can recover energy from a discharge
pressure of captured carbon dioxide when the captured carbon
dioxide is treated by a method such as fixation or conversion.
[0004] (b) Background Art
[0005] Generally, methods for capturing carbon dioxide include an
absorption method, an adsorption method, and a separation membrane
method. Absorption methods can treat a large amount of exhaust gas
compared to adsorption methods and separation membrane methods, and
provides a high removal efficiency even in cases when the CO.sub.2
concentration condition is about 7% to about 30%. Further,
adsorption methods have a high economical efficiency and are easy
to apply.
[0006] The carbon dioxide, once captured, can then be stored, or
can be treated by fixation and conversion methods. Among these, the
method of storing CO.sub.2 in the ground or deep sea is easy even
with a large amount of CO.sub.2, in contrast to the other treatment
methods. Such storage methods are currently available are have been
commercialized. However, the cost for storing CO.sub.2 in the
ground or deep sea is high, and the stored CO.sub.2 cannot be
fundamentally removed, making additional profit-making
difficult.
[0007] The methods of converting captured CO.sub.2 into other
chemical substances using CO.sub.2 as a carbon source, and fixing
CO.sub.2 using plants and seaweeds are both being studied. If such
methods reach a commercialization stage, CO.sub.2 can be
fundamentally removed, and useful products produced thereby can
allow for additional profit-making. Accordingly, these methods are
being evaluated as more economical and preferable technologies.
[0008] Among the absorption methods for capturing carbon dioxide, a
chemical absorption method is currently being most widely
developed. In a chemical absorption method, CO.sub.2 is selectively
separated from exhaust gas by a chemical reaction. With chemical
absorption, the amount of absorption is not significantly affected
by the CO.sub.2 partial pressure. Accordingly, there is an
advantage in that the CO.sub.2 removal efficiency is high even when
the CO.sub.2 partial pressure is low. However, the chemical
absorption method is limited because high energy consumption is
required in a subsequent recovery process in which CO.sub.2 is
separated from an absorbent. For example, it is known that the
energy cost for recovery accounts for about 60% or more of the
total CO.sub.2 recovery cost of a CO.sub.2 capturing apparatus. In
particular, it is known that the energy cost for separating
CO.sub.2 from absorbent in a recovery tower accounts for about 80%
of the energy cost for CO.sub.2 recovery, and the energy cost for
maintaining process equipment such as a pump accounts for about 20%
of the energy cost for CO.sub.2 recovery.
[0009] Accordingly, an improved absorption technology is needed for
capturing carbon dioxide wherein energy consumed in absorbent
recovery is reduced, thereby reducing the cost for collecting
carbon dioxide.
[0010] Hereinafter, a typical carbon dioxide capturing processing
will be described in brief.
[0011] As shown in FIG. 2, an exhaust gas containing CO.sub.2 is
supplied to an absorption tower 10 that has a wide surface area for
smooth gas-liquid contact and which is filled with filling
substances.
In this case, a liquid absorbent is supplied from an absorbent
storage tank 12 to an upper part of the absorption tower 10, and an
exhaust gas is supplied to a lower part of the absorption tower 10.
the exhaust gas contacts the liquid absorbent (absorption solution)
at an atmospheric pressure in the upper end of the absorption tower
10, allowing CO.sub.2 in the exhaust gas to be absorbed into the
absorption solution, generally within a temperature range of
40.degree. C. to 70.degree. C.
[0012] The absorbent that absorbs CO.sub.2 is discharged from the
absorption tower 10 and is supplied to a recovery tower 14 where it
undergoes a recovery process in which the absorbent is heated to a
temperature of 100.degree. C. to 160.degree. C. Thereafter, the
absorbent is discharged from the lower part of the recovery tower
14 ("used CO.sub.2 absorbent") and it is resupplied to the
absorption tower 10 through an absorbent supplying line 22.
[0013] Absorbent that is resupplied to the absorption tower 10 is
heated by passing through a heat exchanger 16. As shown, absorbent
newly supplied to the recovery tower 14 from the absorbent storage
tank 12 can be preheated by heat exchange with the heated absorbent
that is resupplied from the lower part of the recovery tower 14.
This combined heated absorbent is then supplied to the upper part
of the recovery tower 14.
[0014] During the recovery process in which absorbent is heated to
a temperature of 100.degree. C. to 160.degree. C. in the recovery
tower 14, evaporated absorbent and CO.sub.2 is discharged from the
upper part of the recovery tower 14. Absorbent with CO.sub.2 is
discharged from the lower part of the recovery tower 14 and is
heated to a temperature range of 100.degree. C. to 160.degree. C.
by a heater 18, such as a boiler, to separate CO.sub.2 from the
absorbent.
[0015] CO.sub.2 separated in the recovery tower 14 is discharged
through a condenser to locations for storage, fixation, and
conversion, and the evaporated absorbent is condensed in the
condenser 20 then fed back to the recovery tower 14.
[0016] The CO.sub.2 separated in the recovery tower 14 is a high
concentration of gaseous CO.sub.2 (90% to 100%), and is discharged
from the recovery tower 14 at a pressure range of 1.9 atm to 6 atm
to be finally treated by a storage, fixation, or conversion
method.
[0017] In order to store captured CO.sub.2 in the ground or deep
sea, the pressure of a high concentration of CO.sub.2 discharged
from the upper end of the recovery tower 14 must be increased to a
high pressure of about 70 atm to about 100 atm. For this pressure
increase, additional energy is required.
[0018] On the other hand, when captured CO.sub.2 is directly
treated by fixation or conversion instead of storage, the captured
CO.sub.2 can be treated by a pressure of just 1.2 atm or less and,
thus, a process of increasing the pressure of CO.sub.2 with a
compressor is unnecessary.
[0019] The above information disclosed in this Background section
is only for enhancement of understanding of the background of the
invention and therefore it may contain information that does not
form the prior art that is already known in this country to a
person of ordinary skill in the art.
SUMMARY OF THE DISCLOSURE
[0020] The present invention provides an apparatus and method for
recovering energy after carbon dioxide capture, which reduces a
discharge pressure of captured CO.sub.2 to a pressure necessary for
fixation or conversion. The apparatus and method further
simultaneously generates energy (e.g. in a generator connected to a
turbine), wherein the energy is generated by fixation or conversion
of the captured CO.sub.2 instead of storing the captured CO.sub.2
in the ground or deep sea. This generated energy can be supplied to
process operating units of the present apparatus and, thus, can be
used by any of the operating units to capture CO.sub.2.
[0021] In one aspect, the present invention provides an apparatus
for recovering energy after carbon dioxide capture, including an
energy recovery unit at a carbon dioxide discharge part of a carbon
dioxide capturing apparatus, wherein the energy recovery unit
reduces a discharge pressure of the carbon dioxide to a pressure
level suitable for a fixation or conversion treatment. According to
various embodiments, energy generated during the pressure reduction
can be simultaneously recovered by the energy recovery unit.
[0022] In an exemplary embodiment, the energy recovery unit may be
in connection with one or more process operating units of the
carbon dioxide capturing apparatus to supply the recovered
electrical energy to the desired process operating units.
[0023] In another exemplary embodiment, the energy recovery unit
may include: a turbine disposed at an outlet of a condenser,
wherein the outlet is a discharge part of the carbon dioxide
capturing apparatus; and a generator connected to the turbine.
[0024] In another aspect, the present invention provides a method
for recovering energy after carbon dioxide capture, including:
capturing, by a carbon dioxide capturing apparatus, carbon dioxide
from an exhaust gas; discharging, by the carbon dioxide capturing
apparatus, the captured carbon dioxide; reducing a discharge
pressure of the discharged carbon dioxide to a pressure level
suitable for a fixation or conversion treatment; and recovering
energy generated during the pressure reduction.
[0025] In an exemplary embodiment, the method may further include
supplying the recovered energy to one or more desired process
operating units of the carbon dioxide capturing apparatus to
utilize the recovered energy.
[0026] In another exemplary embodiment, the energy recovery may
include: rotating a turbine using the discharge pressure of the
carbon dioxide captured by the carbon dioxide capturing apparatus;
continually reducing a final discharge pressure of the carbon
dioxide that has passed the turbine to the pressure level suitable
for the fixation or conversion treatment; and delivering a rotary
force of the turbine to a generator connected to the turbine to
enable generation of energy by the generator.
[0027] In still another exemplary embodiment, when the discharge
pressure of the carbon dioxide captured by the carbon dioxide
capturing apparatus ranges from about 1.8 atm to about 6 atm, the
final discharge pressure of the carbon dioxide that has passed the
turbine may be reduced to a pressure of less than about 1.8 atm,
less than about 1.6 atm, less than about 1.4 atm, or a pressure of
about 1.2 atm which is suitable for the fixation or conversion
treatment.
[0028] Other aspects and exemplary embodiments of the invention are
discussed infra.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] The above and other features of the present invention will
now be described in detail with reference to certain exemplary
embodiments thereof illustrated the accompanying drawings which are
given hereinbelow by way of illustration only, and thus are not
limitative of the present invention, and wherein:
[0030] FIG. 1 is a diagram illustrating an apparatus for recovering
energy after carbon dioxide capture according to an embodiment of
the present invention; and
[0031] FIG. 2 is a diagram illustrating a typical carbon dioxide
capturing apparatus.
[0032] Reference numerals set forth in the Drawings includes
reference to the following elements as further discussed below:
[0033] 10: absorption tower [0034] 12: absorbent storage tank
[0035] 14: recovery tower [0036] 16: heat exchanger [0037] 18:
heater [0038] 20: condenser [0039] 22: absorbent supplying line
[0040] 30: energy recovery unit [0041] 32: turbine [0042] 34:
generator
[0043] It should be understood that the appended drawings are not
necessarily to scale, presenting a somewhat simplified
representation of various preferred features illustrative of the
basic principles of the invention. The specific design features of
the present invention as disclosed herein, including, for example,
specific dimensions, orientations, locations, and shapes will be
determined in part by the particular intended application and use
environment.
[0044] In the figures, reference numbers refer to the same or
equivalent parts of the present invention throughout the several
figures of the drawing.
DETAILED DESCRIPTION
[0045] Hereinafter reference will now be made in detail to various
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings and described below. While
the invention will be described in conjunction with exemplary
embodiments, it will be understood that present description is not
intended to limit the invention to those exemplary embodiments. On
the contrary, the invention is intended to cover not only the
exemplary embodiments, but also various alternatives,
modifications, equivalents and other embodiments, which may be
included within the spirit and scope of the invention as defined by
the appended claims.
[0046] It is understood that the term "vehicle" or "vehicular" or
other similar term as used herein is inclusive of motor vehicles in
general such as passenger automobiles including sports utility
vehicles (SUV), buses, trucks, various commercial vehicles,
watercraft including a variety of boats and ships, aircraft, and
the like, and includes hybrid vehicles, electric vehicles, plug-in
hybrid electric vehicles, hydrogen-powered vehicles and other
alternative fuel vehicles (e.g., fuels derived from resources other
than petroleum). As referred to herein, a hybrid vehicle is a
vehicle that has two or more sources of power, for example both
gasoline-powered and electric-powered vehicles.
[0047] The above and other features of the invention are discussed
infra.
[0048] Hereinafter, exemplary embodiments of the present invention
will be described in detail with reference to the accompanying
drawings.
[0049] The present invention provides an apparatus and method that
improves the economical efficiency of CO.sub.2 capture by reducing
the CO.sub.2 absorption cost, particularly by reducing energy
costs.
[0050] According to the present invention, a CO.sub.2 capturing
apparatus is designed to discharge captured CO.sub.2 for conversion
or fixation after reducing the discharge pressure of the CO.sub.2
to a pressure level suitable for fixation or conversion treatment,
wherein energy is recovered during the pressure reduction, and the
recovered energy is supplied to one or more of process units of the
CO.sub.2 capturing apparatus.
[0051] According to an exemplary embodiment, as shown in FIG. 1, an
energy recovery unit 30 may be disposed around a location where
CO.sub.2 captured by the CO.sub.2 capturing apparatus is
discharged. For example, the energy recovery unit 30 may be
disposed at the side of an outlet of a condenser 20 connected to a
recovery tower 14 of the CO2 capturing apparatus.
[0052] When CO.sub.2 captured in the CO.sub.2 capturing apparatus
is discharged from the outlet of the condenser 20, the energy
recovery unit 30 may be configured and arranged to reduce the
discharge pressure of CO.sub.2 to a pressure level suitable for
fixation or conversion treatment, and to recover energy generated
during the pressure reduction.
[0053] More specifically, the energy recovery unit 30 according to
an embodiment of the present invention may include a turbine 32
disposed at an outlet of the condenser 20 that is a discharge part
of the CO.sub.2 capturing apparatus. A generator 34 can be provided
in connection with the turbine 32, for example, by concentrically
connecting the generator 34 to the turbine 32 or by other suitable
arrangements.
[0054] The generator 34 of the energy recovery unit 30 may be
connected to one or more process operating units (e.g., pump and
blower disposed in each capture process, which are typically driven
by electrical energy) of the CO.sub.2 capturing apparatus so as to
supply generated electrical energy to the respective process
operating units.
[0055] Hereinafter, a method of recovering energy after CO.sub.2
capture according to an embodiment of the present invention will be
described as follows.
[0056] As shown in FIG. 1, exhaust gas containing CO.sub.2 may be
supplied into an absorption tower 10, and absorbent, typically
liquid absorbent, may be supplied from an absorbent storage tank 12
to an upper part of the absorption tower 10.
[0057] The exhaust gas supplied into the absorption tower 10 may
contact liquid absorbent (absorption solution), typically at an
atmospheric pressure, in the absorption tower 10 (e.g. in the upper
part of the absorption tower 10), and CO.sub.2 within the exhaust
gas may be absorbed by the absorbent.
[0058] The absorbent that absorbs CO.sub.2 ("used CO.sub.2
absorbent") is discharged from the absorption tower 10, and is
supplied to a recovery tower 14 where it may then undergo a
recovery process. In particular, in the recovery process the
absorbent is heated to a suitable temperature (such as a
temperature of about 100.degree. C. to about 160.degree. C.) in the
recovery tower 14.
[0059] The absorbent recovered in the recovery process is
discharged from the lower part of the recover tower 14, and may
then be resupplied to the absorption tower 10 via an absorbent
supplying line 22 which connects the absorbent storage tank 12 and
the absorption tower 10.
[0060] As shown, the resupplied absorbent passes through a heat
exchanger 16, and thereafter combines with CO.sub.2 absorbent newly
supplied from the absorption tower 10. As such, the newly supplied
CO.sub.2 absorbent may be preheated by heat exchange with the
heated resupplied absorbent, and the combined absorbent (newly
supplied absorbent and resupplied absorbent) may then be supplied
to the upper part of the recovery tower 14.
[0061] During the recovery process in which absorbent is heated to
a suitable temperature, such as a temperature of about 100.degree.
C. to about 160.degree. C., evaporated absorbent with CO.sub.2 may
be discharged from the upper part of the recovery tower 14.
Further, liquid absorbent with CO.sub.2 may be discharged from the
lower part of the recovery tower 14, may pass through a heater 18
(e.g. a boiler or the like) where it is heated to a suitable
temperature range, such as a temperature of about 100.degree. C. to
about 160.degree. C., so as to separate CO.sub.2 from the
absorbent.
[0062] CO.sub.2 separated in the recovery tower 14, i.e., CO.sub.2
with evaporated absorbent, may be discharged to a condenser 20.
From the condenser, condensed absorbent may be resupplied to the
recovery tower 14, while separated CO.sub.2 may be discharged to a
location for fixation or conversion treatment.
[0063] When separated CO.sub.2 is discharged from the condenser 20
to the location for the fixation or conversion treatment, the
pressure of CO.sub.2 may range from about 1.8 atm to about 6 atm. A
suitable discharge pressure of CO.sub.2 necessary for the fixation
or conversion treatment may be less than this discharge pressure,
and, for example, may be less than 1.8 atm, less than 1.6 atm, less
than 1.4 atm, and in some embodiments, may be about 1.2 atm.
[0064] As shown in the embodiment of FIG. 1, separated CO.sub.2
discharged from the condenser 20 at a pressure of about 1.8 atm to
about 6 atm is passes through the turbine 32 of the energy recovery
apparatus 30. As the separated CO.sub.2 passes through the turbine,
the turbine 32 may be rotated, and the rotary force of the turbine
32 may be delivered to the generator 34.
[0065] While the separated CO.sub.2 discharged from the condenser
20 passes through the turbine 32, the pressure of CO.sub.2 may be
reduced to a suitable pressure level for the fixation or conversion
treatment. In particular, according to an exemplary embodiment,
separated CO.sub.2 is discharged from the condenser 20 at a
pressure of about 1.8 atm to about 6 atm, and passes through the
turbine 32 where the pressure of the CO.sub.2 is constantly or
continuously reduced as needed to a suitable pressure level for
fixation or conversion treatment.
[0066] For example, the final discharge pressure of CO.sub.2 that
has passed through the turbine 32 may be reduced to a pressure of
about 1.2 atm, which is a suitable pressure for the subsequent
fixation or conversion treatment.
[0067] As the CO.sub.2 passes through the turbine and is reduced in
pressure, the rotary force of the turbine 32 may be delivered to
the generator 34, enabling the generation of energy by the
generator 34. Electrical energy generated in the generator 34 may
be supplied to and consumed in one or more of the process operating
units (e.g., pump and blower disposed in each capture process and
driven by electrical energy) of the CO.sub.2 capturing
apparatus.
[0068] As a result, the amount of energy that must be supplied
(i.e. external energy) to operate the CO.sub.2 capturing apparatus
can be significantly reduced, and costs can be saved by utilizing
electrical energy generated in the generator 34 of the energy
recovery unit 30 as energy for powering one or more of the process
operating units of the CO.sub.2 capturing apparatus.
[0069] As a test example of the present invention, a test of energy
recovery was performed using a process simulation program in which
the amount of CO.sub.2 capture (removal) was about 1000 ton/day.
The CO.sub.2 absorption process conditions are shown in Table 1
below.
TABLE-US-00001 TABLE 1 Gas-liquid flow ratio 125 150 175 200 225
Flow rate of exhaust gas, 2,125.6 2,125.6 2,125.6 2,125.6 2,125.6
m3/min CO.sub.2 concentration, 20 20 20 20 20 mol % Flow rate of
absorbent, 17.0 14.2 12.1 10.7 9.4 m3/min MEA concentration in 35
35 35 35 35 absorption tower, wt %
[0070] The consumed energy kW of a reboiler (e.g., heater 18
connected to the lower part of the recovery tower 14) for each
gas-liquid flow ratio and the flow rate of CO.sub.2 gas discharged
from the condenser are shown in Table 2 below.
TABLE-US-00002 TABLE 2 Gas-Liquid Flow Ratio 125 150 175 200 225
Amount of 1,000 1,000 1,000 1,000 1,000 CO.sub.2 Removal, ton/day
Energy Used 697.2 577.2 489.8 425.0 376.0 in Absorbent Pump, kW
Flow Rate of 77.95 79.50 80.88 81.97 83.50 CO.sub.2 discharged from
Condenser, m3/min Pressure of 4.41 4.32 4.25 4.20 4.12 CO.sub.2
discharged from Condenser, atm
[0071] The simulation results of energy generated through the
turbine for each gas-liquid flow ratio according to the above test
conditions are shown in Table 3 below.
TABLE-US-00003 TABLE 3 Division Wet radical flow Dry radical flow
Gas-Liquid Flow Ratio 125 150 175 200 225 125 150 175 200 225
Pressure of 4.41 4.32 4.25 4.20 4.12 4.41 4.32 4.25 4.20 4.12
CO.sub.2 injected into turbine, ata Pressure of 1.20 1.20 1.20 1.20
1.20 1.20 1.20 1.20 1.20 1.20 CO.sub.2 discharged from turbine, atm
Turbine 0.75 0.75 0.75 0.75 0.75 0.85 0.85 0.85 0.85 0.85
efficiency Generated 177.3 176.1 175.1 174.2 173.0 223.9 222.4
221.0 220.0 218.5 energy, kW Reduction rate 25.4 30.5 35.7 41.0
46.0 32.1 38.5 45.1 51.8 58.1 of energy used in absorbent pump,
%
[0072] As shown in Table 3, the pressure of CO.sub.2 inputted into
the turbine ranged from about 4.12 atm to about 4.41 atm regardless
of a wet or dry flow, and the pressure of CO.sub.2 discharged into
a fixation or conversion treatment unit through the turbine is
constantly reduced to about 1.20 atm. Also, as energy generated by
the generator increased according to the turbine efficiency, energy
used in the absorbent pump of the CO.sub.2 capturing apparatus was
reduced.
[0073] According to the embodiments of the present invention, when
CO.sub.2 captured by the CO.sub.2 capturing apparatus are processed
by fixation or conversion treatment instead of a method of storing
CO.sub.2 in the ground or deep sea, the discharge pressure of
CO.sub.2 captured by the CO.sub.2 capturing apparatus can be
reduced to a pressure necessary for the fixation or conversion
treatment. An energy recovery unit can be provided to generate
energy from the pressure reduction, particularly wherein a turbine
is positioned through which captured CO.sub.2 passes such that the
rotary force of the turbine can be delivered to a generator to
obtain an energy recovery effect in which electrical energy is
produced.
[0074] Also, since electrical energy produced in the generator can
be utilized as energy for driving various process operating units
(e.g., pump and blower) of the CO.sub.2 capturing apparatus, energy
(i.e., externally supplied energy) necessary for operating the
apparatus to capture CO.sub.2 can be significantly saved.
[0075] The invention has been described in detail with reference to
exemplary embodiments thereof. However, it will be appreciated by
those skilled in the art that changes may be made in these
embodiments without departing from the principles and spirit of the
invention, the scope of which is defined in the appended claims and
their equivalents.
* * * * *