JP2012161750A - Co2 recovery method and co2 recovery apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a COrecovery method and a recovery apparatus, which can reduce a liquefaction power of recovered COin a process for recovering and liquefying COby contacting a fuel gas that contains COwith an absorption liquid.SOLUTION: The COrecovery method from the fuel gas 1 that contains COincludes: a first compression process 11 for compressing the fuel gas 1; an absorption process 17 for cooling the fuel gas 1 compressed in the first compression process 11 and removing condensed water, then bringing it into contact with the absorption liquid, so that the COin the fuel gas 1 is absorbed by the absorption liquid and a purification gas is obtained; a first heating process 14 for heating the absorption liquid 2 which has absorbed the COin the absorption process 17 with the fuel gas 1 compressed by the first compression process 11 as a heat source; a regeneration process 20 for decompressing the absorption liquid 2 heated in the first heating process 14 to emit the contained CO, so that the absorption liquid 2 is regenerated; and a first cooling process 22 for cooling the absorption liquid 3 regenerated in the regeneration process 20 before it is used for the absorption process 17.

Description

The present invention relates to a device for a method and recovery for recovering CO ₂ from gasification gas fuel containing CO _2.

In recent years, the greenhouse effect due to CO ₂ has been pointed out as a cause of the global warming phenomenon, and countermeasures are urgently required to protect the global environment. The source of CO ₂ extends to all human activity fields where fossil fuels are burned, and the demand for emission control tends to become stronger. Targeting thermal power plants in particular use a large amount of fossil fuels, the method of combustion exhaust gas containing CO ₂ into contact with an aqueous alkanolamine solution or the like to absorb the CO ₂ to recover the CO _2, and the recovered CO ₂ The method of storing without releasing to the atmosphere has been energetically studied.

Examples of alkanolamines include monoethanolamine (MEA) and N-methyldiethanolamine (MDEA). In the absorption method using an alkanolamine aqueous solution as the absorbing solution, the absorbing solution that has absorbed CO ₂ in the absorption tower is heated and regenerated using steam at about 150 ° C. in the regeneration tower (for example, Patent Documents 1 and 2). . The greater the amount of treatment gas, the greater the amount of absorbent used, and the amount of water vapor required for regeneration increases accordingly. Therefore, when a gasified gas such as coal or oil coke is used as a target, the amount of gas increases due to combustion, so a method of recovering CO ₂ before combustion is desirable.

In general, since the pressure of the gasification gas is as high as several MPa, the absorbing liquid that has absorbed CO ₂ under the same pressure as the gas pressure can be regenerated by releasing CO ₂ by reducing the pressure. In this regeneration method, unlike the heat regeneration, it is not necessary to use a large amount of water vapor, so that CO ₂ can be recovered with less energy. Moreover, in IGCC (coal gasification combined cycle power generation), the fall of a power generation end output can be suppressed. However, on the other hand, since the pressure of the CO ₂ released from the absorbing liquid is low, the power required for the liquefaction process for transferring and storing the recovered CO ₂ increases, and as a result, the power transmission end output decreases. Sometimes.

JP 03-193116 A JP 2006-232596 A

As described above, in the method of regenerating by releasing CO ₂ by reducing the pressure of the absorbing liquid that has absorbed CO ₂ under the same pressure as the gas pressure, the energy required for regeneration can be reduced, but recovered. There is a problem that the liquefaction power of CO ₂ increases.

The present invention is recovered in a process of recovering and liquefying CO ₂ by bringing a fuel gas containing CO ₂ into contact with an absorbing liquid such as gasification gas or natural gas of carbon containing fuel such as coal and petroleum pitch, and natural gas. reducing the liquefaction power of the CO _2, and to provide a CO ₂ recovery method and recovery apparatus for reducing energy consumption needed for recovery and liquefaction of CO _2.

The CO ₂ recovery method according to the present invention has the following characteristics.

In a method for recovering CO ₂ from fuel gas containing CO ₂ , a first compression step for compressing the fuel gas, and cooling the fuel gas compressed in the first compression step to remove condensed water by contacting the absorption liquid, the absorption step to obtain purified gas of CO ₂ of the fuel gas is absorbed in the absorbing liquid, the absorbent having absorbed CO ₂ in the absorption step, the first compression step A first heating step in which the fuel gas compressed in step 1 is heated as a heat source, and the absorbing liquid heated in the first heating step is depressurized to release the contained CO ₂ to regenerate the absorbing liquid. A regeneration step, and a first cooling step of cooling the absorbent regenerated in the regeneration step before use in the absorption step.

According to the present invention, since the pressure of the recovered CO ₂ is increased, it is possible to significantly reduce the power required to the recovery and liquefaction of CO _2.

Pressure CO ₂ and is a diagram showing the relationship of the liquefied power. The structure of the CO ₂ recovery apparatus according to Embodiment 1 of the present invention is a block diagram showing. The configuration of a CO ₂ recovery apparatus according to Example 2 of the present invention is a block diagram showing. The configuration of a CO ₂ recovery apparatus according to Example 3 of the present invention is a block diagram showing. The structure of the CO ₂ recovery apparatus according to Example 4 of the present invention is a block diagram showing.

The outline of the CO ₂ recovery method according to the present invention is as follows.

The fuel gas containing CO ₂ is introduced into the absorption tower after being pressurized and compressed. In the absorption tower, CO ₂ in the fuel gas is absorbed by the absorption liquid. The absorption liquid that has absorbed CO ₂ is extracted from the bottom of the absorption tower and heated using the compressed fuel gas as a heat source. The heated absorbent is depressurized and releases the absorbed CO ₂ to regenerate. The regenerated absorption liquid is introduced into the absorption tower from the top. On the other hand, the fuel gas used for heating the absorption liquid is introduced into the absorption tower after moisture is removed.

According to the present invention, by pressurizing and compressing the fuel gas containing CO ₂ at the front stage of the absorption tower, the pressure level when regenerating the absorbent and the pressure of the recovered CO ₂ can be made higher than before. When the pressure of the recovered CO ₂ is high, there is an advantage that power (liquefaction power) when liquefying this CO ₂ is reduced.

FIG. 1 is a diagram showing the relationship between the pressure of CO ₂ and the liquefaction power when the recovered CO ₂ is pressurized and liquefied. The vertical axis represents the power necessary for changing CO ₂ at the pressure shown on the horizontal axis to liquid CO ₂ at 30 ° C. at 10 MPa. As shown in FIG. 1, the liquefaction power gradually approaches zero as the pressure of CO ₂ increases, so it can be seen that the higher the pressure, the more liquefied CO ₂ can be.

Further, by pressurizing the fuel gas containing CO ₂ at a front stage of the absorption column, it is possible to reduce the container volume, such as absorption tower or flash drum to absorb CO _2. Further, since the temperature of the pressurized fuel gas rises, it can be used as a heating source necessary for the regeneration of the absorbing liquid, and heating steam that has been necessary in the past is not necessary.

Therefore, according to the present invention, to reduce the liquefaction power of the recovered CO _2, it is possible to reduce the energy consumption necessary for the recovery and liquefaction of CO _2.

Hereinafter, the absorption liquid extracted from the bottom of the absorption tower is referred to as “rich liquid”, and the absorption liquid regenerated by releasing CO ₂ is referred to as “semi-lean liquid”.

The target fuel gas in the present invention is a gas containing CO ₂ such as a gas or natural gas generated when a fuel containing carbon such as coal, petroleum pitch or heavy oil is partially oxidized.

  Although embodiments of the present invention will be described below, the present invention is not limited to the following embodiments.

An embodiment of the CO ₂ recovery method and recovery apparatus according to the present invention will be described with reference to FIG. Example 1 is an example in which the basic configuration of the CO ₂ recovery method and the recovery apparatus according to the present invention is applied to a CO ₂ recovery process from coal gasification gas.

FIG. 2 is a block diagram showing the configuration of the CO ₂ recovery apparatus in the present embodiment. As shown in FIG. 2, the CO ₂ recovery apparatus in this embodiment mainly includes a first compressor 11, a first rich liquid heater 14, a fuel gas cooler 15, a gas-liquid separator 16, and an absorption. The tower 17, the rich liquid turbine 19, the flash drum 20, the absorption liquid circulation pump 21, and the first absorption liquid cooler 22 are configured.

The fuel gas 1 obtained by gasifying coal is introduced into the first compressor 11 and pressurized and compressed. The temperature of the compressed fuel gas 1 rises. Next, the fuel gas 1 is introduced into the first rich liquid heater 14 and is cooled by heat exchange with the rich liquid 2 extracted from the bottom of the absorption tower 17. The fuel gas 1 is further cooled to 50 ° C. or lower by the fuel gas cooler 15, and after the condensed water 6 is removed by the steam separator 16, the fuel gas 1 is introduced into the absorption tower 17. The semi-lean liquid 3 is supplied from the top of the absorption tower 17, and the fuel gas 1 comes into contact with the semi-lean liquid 3 to remove CO _2, which is an acidic gas, and a purified gas 4 is obtained.

On the other hand, the rich liquid 2 that has absorbed the acid gas is heated by the fuel gas 1 by the first rich liquid heater 14 and then introduced into the rich liquid turbine 19. In the rich liquid turbine 19, the discharge side pressure is adjusted to be lower than the pressure in the absorption tower 17, and the turbine is rotated by the discharge pressure of the rich liquid 2 so that power is recovered. The rich liquid 2 discharged from the rich liquid turbine 19 is introduced into the flash drum 20 to be depressurized and separated into a semi-lean liquid 3 and an acidic gas 5 containing CO ₂ as a main component. Therefore, CO ₂ in the fuel gas is recovered as the acid gas 5.

  The semi-liquid 3 is pressurized by the absorption liquid circulation pump 21, cooled by cooling water by the first absorption liquid cooler 22, and then introduced into the absorption tower 17. In the first absorbing liquid cooler 22, heat loss is generated by cooling the semi-lean liquid 3 with cooling water.

Here, a fuel gas having a flow rate of 170,000 m ³ _N / h (the subscript N represents a normal flow rate), a CO ₂ concentration of 32.6%, a pressure of 2.5 MPa, and a temperature of 40 ° C. is used for CO _2. A case where the present embodiment is applied when collecting the data will be described below. The recovered CO ₂ is pressurized to liquid CO ₂ at 30 MPa at 10 MPa. The liquefaction power required at this time can be obtained from FIG. In this example, the CO ₂ recovery apparatus is operated so that the carbon recovery rate obtained by the following formula (1) is 90%.

The fuel gas 1 is increased from 40 ° C. to 128 ° C. by being pressurized and compressed to 5.1 MPa by the first compressor 11. When the flow rate of the semi-lean liquid 3 supplied from the top of the absorption tower 17 was 1900 t / h and the temperature was 43 ° C., the temperature of the rich liquid 2 that absorbed CO ₂ was 62 ° C. The rich liquid 2 was extracted from the bottom of the absorption tower 17, heated by the fuel gas 1 in the first rich liquid heater 14, and increased to 100 ° C. The rich liquid 2 was introduced into the rich liquid turbine 19 having a protruding pressure set to 1.1 MPa to recover power, and then introduced into the flash drum 20. The internal temperature of the flash drum 20 decreased to 90 ° C. due to a decrease in pressure, and an acid gas 5 and a semi-lean liquid 3 of 55,000 m ³ _N / h were obtained.

By pressurizing the fuel gas 1 with the first compressor 11 and raising the temperature, the rich liquid 2 is heated by the fuel gas 1 with the first rich liquid heater 14 and the temperature and pressure rise. For this reason, the protrusion pressure of the rich liquid turbine 19 can be set to 1.1 MPa higher than usual, and the pressure of the acidic gas 5 containing CO ₂ as a main component in the flash drum 20 is also 1.1 MPa. From FIG. 1, the liquefaction power of CO _{2 at} a pressure of 1.1 MPa is 5.5 MW.

The carbon recovery rate determined by the formula (1) from the amount of CO ₂ contained in the acidic gas 5 was 90%.
η = FoCO ₂ / (FiCO + FiCH ₄ + FiCO ₂ ) × 100 (1)
η: Carbon recovery rate (%)
FiCO: CO flow rate at the absorption tower inlet (m ³ _N / h)
FiCH ₄ : Flow rate of CH ₄ at the absorption tower inlet (m ³ _N / h)
FiCO ₂ : CO ₂ flow rate at the absorption tower inlet (m ³ _N / h)
FoCO ₂ : CO ₂ flow rate at the outlet of the flash drum (m ³ _N / h)
FiCO, FiCH ₄ , and FiCO ₂ were obtained by multiplying the flow rate of the fuel gas 1 by the concentration of CO, the concentration of CH ₄ , and the concentration of CO _{2 in} the fuel gas 1, respectively. FoCO ₂ was obtained by multiplying the flow rate of the acidic gas 5 by the concentration of CO ₂ in the acidic gas 5.

When the first compressor 11 does not pressurize and compress the fuel gas 1, the temperature of the fuel gas 1 does not rise, so the rich liquid 2 is not sufficiently heated by the first rich liquid heater 14, and the fuel The temperature and pressure are lower than when the gas 1 is pressurized and compressed. Therefore, in order to remove CO ₂ from the fuel gas 1 that is not pressurized and compressed by the first compressor 11 and to obtain a carbon recovery rate of 90%, the protruding pressure of the rich liquid turbine 19 is set to 0.1 MPa. There is a need. For this reason, in the flash drum 20, the pressure of the acidic gas 5 containing CO ₂ as a main component is also 0.1 MPa. From FIG. 1, the liquefaction power of CO _{2 at} a pressure of 0.1 MPa is 10.4 MW.

From the above results, in the present embodiment in which the fuel gas 1 is compressed by the first compressor 11, power is required to compress the fuel gas 1, but the liquefaction power of the recovered CO ₂ is 10.4 MW to 5.5 MW. Could be reduced. Therefore, according to the present embodiment, it is possible to reduce energy consumption necessary for CO ₂ recovery and liquefaction.

Further, since the heating source for regenerating the rich liquid 2 can be covered only by the fuel gas 1 whose temperature has been increased by pressurization and compression, it is not necessary to use water vapor as in the prior art. As a result, the required power of the entire CO ₂ recovery process based on this example was 24 MW, which was reduced by about 10% from 27 MW of the conventional CO ₂ recovery process. Therefore, when the CO ₂ recovery process based on the present embodiment is applied to a power plant, there is an effect that it is possible to suppress a reduction in power transmission end efficiency due to CO ₂ recovery.

A second embodiment of the CO ₂ recovery method and recovery apparatus according to the present invention will be described with reference to FIG. Example 2 is an example in which the CO ₂ recovery method and the recovery apparatus according to the present invention are applied to a CO ₂ recovery process from coal gasification gas, as in Example 1, except for the following points. That is, the semi-lean liquid is used as a heat source, the rich liquid before being heated with the fuel gas is pre-heated, and the purified gas is used to cool the semi-lean liquid.

FIG. 3 is a block diagram showing the configuration of the CO ₂ recovery device in the present embodiment. 3, the same reference numerals as those in FIG. 2 denote the same or common elements as those in FIG. The CO ₂ recovery apparatus of the present example has the same configuration as that of Example 1, but a second rich liquid heater 18 is installed between the absorption tower 17 and the first rich liquid heater 14. The difference is that a second absorbing liquid cooler 23 is installed between the first absorbing liquid cooler 22 and the second rich liquid heater 18.

The CO ₂ recovery method in this example is the same as that in Example 1, and only the differences will be described below.

  The semi-lean liquid 3 separated from the acid gas 5 and regenerated by the flash drum 20 is introduced into the second rich liquid heater 18 and the rich liquid 2 is heated, and at the same time, the semi-lean liquid 3 is cooled. The heated rich liquid 2 is introduced into the first rich liquid heater 14 and further heated by the fuel gas 1. The cooled semi-lean liquid 3 is introduced into the second absorption liquid cooler 23 and further cooled by the purified gas 4. Thereafter, the first absorption liquid cooler 22 is further cooled by cooling water. On the other hand, the purified gas 4 is heated by the semi-lean liquid 3 in the second absorption liquid cooler 23.

Thus, the rich liquid 2 can be heated to a higher temperature by heating the rich liquid 2 with the semi-lean liquid 3 in advance using the second rich liquid heater 18 and then heating with the fuel gas 1. . As a regeneration characteristic of the absorbing liquid (rich liquid 2), if the temperature is increased, it can be regenerated even at a high pressure. As a result, it is possible to further reduce the CO ₂ liquefaction power at the subsequent stage.

In addition, the semi-lean liquid 3 is not only cooled by the first absorbing liquid cooler 22 with cooling water, but also the rich liquid 2 and purified gas are cooled by the second rich liquid heater 18 and the second absorbing liquid cooler 23. Cooling 4 as a cooling medium also has the advantage that the amount of cooling water used can be reduced and the power of the circulating pump for cooling water can be reduced. Therefore, when the CO ₂ recovery process based on the present embodiment is applied to a power plant, it is possible to further suppress a reduction in power transmission end efficiency due to CO ₂ recovery, and further improve the power generation end efficiency.

A third embodiment of the CO ₂ recovery method and recovery apparatus according to the present invention will be described with reference to FIG. Example 3 is an example in which the CO ₂ recovery method and the recovery device according to the present invention are applied to IGCC (Coal Gasification Combined Cycle).

FIG. 4 is a block diagram showing the configuration of the CO ₂ recovery device in the present embodiment. 4, the same reference numerals as those in FIGS. 2 and 3 indicate the same or common elements as those in FIGS. 2 and 3. The CO ₂ recovery device of the present embodiment includes a second compressor 13, an expansion turbine 24, and a fuel gas cooler 25 in addition to the devices shown in FIGS. 2 and 3.

The CO ₂ recovery method in this example is the same as that in Example 1, and only the differences will be described below.

  The second compressor 13 is driven by an expansion turbine 24 connected coaxially. The fuel gas 1 introduced into the second compressor 13 is pressurized and compressed, and the temperature rises. The compressed fuel gas 1 is introduced into the fuel gas cooler 25 and cooled to a predetermined temperature, and then introduced into the first compressor 11. The fuel gas 1 is further pressurized and compressed by the first compressor 11 and the temperature rises. Thereafter, the fuel gas 1 is introduced into the first rich liquid heater 14.

  The expansion turbine 24 is coaxially connected to the second compressor 13 and is driven by the purified gas 4. The purified gas 4 drives the expansion turbine 24 to decrease in pressure and at the same time the temperature decreases, and is introduced into the second absorption liquid cooler 23.

  In this embodiment, the semi-lean liquid 3 is introduced from the flash drum 20 to the second rich liquid heater 18, the first absorption liquid cooler 22, and the second absorption liquid cooler 23 in this order. To be cooled.

Thus, according to this embodiment, the purified gas 4 is used to drive the expansion turbine 24, and the second compressor 13 connected coaxially to the expansion turbine 24 is driven to pressurize the fuel gas 1. By compressing, the compression power of the fuel gas 1 by the first compressor 11 can be reduced by about 15% compared to the first embodiment. As a result, the required power of the entire CO ₂ recovery process can be reduced, and the energy consumption required for CO ₂ recovery and liquefaction can be reduced.

Since the temperature of the purified gas 4 is lowered after the expansion turbine 24 is driven, the purified gas 4 can be used as a refrigerant for cooling the semi-lean liquid 3 in the second absorption liquid cooler 23. When the purified gas 4 is introduced into a gas turbine (not shown) and used for power generation, the purified gas 4 is heated by a heating device (not shown) and then introduced into the gas turbine. In the CO ₂ recovery apparatus in the present embodiment, the purified gas 4 is heated by heat exchange with the semi-lean liquid 3, so that the heating amount before introduction into the gas turbine can be reduced. As a result, the heat loss due to the cooling of the semi-lean liquid 3 in the first absorbing liquid cooler 22 could be reduced by about 20% compared to the conventional CO ₂ recovery apparatus.

  In the configuration shown in FIG. 4, the second compressor 13 is located at the front stage of the first compressor 11, but may be located at the rear stage of the first compressor 11. In this case, the fuel gas 1 is introduced into the first compressor 11, the fuel gas cooler 25, and the second compressor 13 in this order.

A fourth embodiment of the CO ₂ recovery method and recovery apparatus according to the present invention will be described with reference to FIG. Example 4 is an example in which a CO ₂ recovery device having the same configuration as that of Example 3 is applied to IGCC (Coal Gasification Combined Cycle).

FIG. 5 is a block diagram showing a configuration of the CO ₂ recovery device in the present embodiment. 5, the same reference numerals as those in FIG. 4 denote the same or common elements as those in FIG. The CO ₂ recovery apparatus of the present embodiment is not provided with the fuel gas cooler 25 in the apparatus shown in FIG. 4, and the third rich liquid heater 12 is provided between the second compressor 13 and the first compressor 11. Have been added in between.

  The fuel gas 1 is pressurized and compressed by the second compressor 13 and the temperature rises. The compressed fuel gas 1 is introduced into the third rich liquid heater 12, cooled by heat exchange with the rich liquid 2, and then introduced into the first compressor 11.

  The rich liquid 2 extracted from the bottom of the absorption tower 17 is heated by the fuel gas 1 in the third rich liquid heater 12. Thereafter, it is introduced into the second rich liquid heater 18 and heated by the semi-lean liquid 3. And it is further heated by the fuel gas 1 which was introduce | transduced into the 1st rich liquid heater 14, was pressurized with the 1st compressor 11, and the temperature rose.

As described above, the rich liquid 2 is preheated using the third rich liquid heater 12 and then heated by the second rich liquid heater 18 and the first rich liquid heater 14, whereby the rich liquid 2 is heated. 2 can be heated to higher temperatures. As the regeneration characteristic of the absorbing liquid (rich liquid 2), if the temperature is increased, it can be regenerated even at a high pressure. As a result, the subsequent stage CO ₂ liquefaction power is obtained from the CO ₂ recovery apparatus shown in Example 3. Can be further reduced.

  In the configuration shown in FIG. 5, the second compressor 13 is located at the front stage of the first compressor 11, but may be located at the rear stage of the first compressor 11. In this case, the fuel gas 1 is introduced into the first compressor 11, the third rich liquid heater 12, and the second compressor 13 in this order.

  DESCRIPTION OF SYMBOLS 1 ... Fuel gas, 2 ... Rich liquid, 3 ... Semi-lean liquid, 4 ... Purified gas, 5 ... Acid gas, 6 ... Condensed water, 11 ... 1st compressor, 12 ... 3rd rich liquid heater, 13 ... 2nd compressor, 14 ... 1st rich liquid heater, 15 ... Fuel gas cooler, 16 ... Gas-liquid separator, 17 ... Absorption tower, 18 ... 2nd rich liquid heater, 19 ... Rich liquid turbine 20 ... Flash drum, 21 ... Absorption liquid circulation pump, 22 ... First absorption liquid cooler, 23 ... Second absorption liquid cooler, 24 ... Expansion turbine, 25 ... Fuel gas cooler.

Claims (13)

In a method for recovering CO ₂ from a fuel gas containing CO ₂ ,
A first compression step of compressing the fuel gas;
The fuel gas compressed in the first compression step is cooled to remove condensed water, and then brought into contact with the absorbing liquid, so that the absorbing liquid absorbs CO ₂ in the fuel gas to obtain a purified gas. An absorption process;
A first heating step of heating the absorption liquid that has absorbed CO ₂ in the absorption step using the fuel gas compressed in the first compression step as a heat source;
A regeneration step of depressurizing the absorbing liquid heated in the first heating step and releasing the contained CO ₂ to regenerate the absorbing liquid;
A first cooling step for cooling the absorbent regenerated in the regeneration step before use in the absorption step;
A CO ₂ recovery method comprising: The CO ₂ recovery method according to claim 1, wherein
A CO ₂ recovery method comprising a _second heating step of heating the absorption liquid that has absorbed CO ₂ in the absorption step, using the absorption liquid regenerated in the regeneration step as a heat source. The CO ₂ recovery method according to claim 1 or 2,
A CO ₂ recovery method comprising a _second cooling step of cooling the absorbent regenerated in the regeneration step using the purified gas obtained in the absorption step. The CO ₂ recovery method according to claim 1 or 2,
A second compression step of compressing the fuel gas using the purified gas obtained in the absorption step as a power source;
The first compression step of compressing the fuel gas compressed in the second compression step;
A second cooling step for cooling the regenerated liquid regenerated in the regenerating step using a purified gas which is a power source in the second compression step;
CO ₂ recovery method having The CO ₂ recovery method according to claim 3,
A second compression step of compressing the fuel gas using the purified gas obtained in the absorption step as a power source;
The first compression step of compressing the fuel gas compressed in the second compression step,
In the second cooling step, a CO ₂ recovery method in which the absorption liquid regenerated in the regeneration step is cooled using purified gas that is used as a power source in the second compression step. The CO ₂ recovery method according to claim 4 or 5,
A CO ₂ recovery method comprising a third heating step of heating the absorbent that has absorbed CO ₂ in the absorption step using the fuel gas compressed in the second compression step as a heat source. In the CO ₂ recovery device for absorbing the CO ₂ absorption liquid from the fuel gas containing CO _2,
A first compressor for compressing the fuel gas;
A fuel gas cooler for cooling the fuel gas compressed by the first compressor;
A gas-liquid separator for separating condensed water from the fuel gas cooled by the fuel gas cooler;
An absorption tower for obtaining purified gas by absorbing CO ₂ contained in the fuel gas compressed by the first compressor into the absorption liquid;
A fuel gas compressed by the first compressor as a heat source, a first rich liquid heater for heating the absorption liquid extracted from the bottom of the absorption tower;
A flash drum that depressurizes the absorption liquid heated by the first rich liquid heater, releases CO ₂ contained therein, and regenerates the absorption liquid;
A first absorption liquid cooler for cooling the absorption liquid regenerated by the flash drum;
A CO ₂ recovery device comprising: The CO ₂ recovery device according to claim 7,
A second rich gas is installed between the absorption tower and the first rich liquid heater, and heats the absorption liquid extracted from the bottom of the absorption tower using the absorption liquid regenerated by the flash drum as a heat source. A CO ₂ recovery device equipped with a liquid heater. The CO ₂ recovery device according to claim 7 or 8,
A CO ₂ recovery device comprising a _second absorption liquid cooler that cools the absorption liquid regenerated by the flash drum using the purified gas. The CO ₂ recovery device according to any one of claims 7 to 9,
An expansion turbine driven by the purified gas as a power source;
A second compressor driven by the expansion turbine to compress the fuel gas;
A CO ₂ recovery device. The CO ₂ recovery device according to claim 7 or 8,
An expansion turbine driven by the purified gas as a power source;
A second compressor driven by the expansion turbine to compress the fuel gas;
A CO ₂ recovery device comprising a _second absorption liquid cooler that cools the absorption liquid regenerated by the flash drum using the purified gas that has driven the expansion turbine. The CO ₂ recovery device according to claim 9,
An expansion turbine driven by the purified gas as a power source;
A second compressor driven by the expansion turbine and compressing the fuel gas,
The second absorption liquid cooler is a CO ₂ recovery device that cools the absorption liquid regenerated by the flash drum using the purified gas that has driven the expansion turbine. The CO ₂ recovery device according to any one of claims 10 to 12,
A CO ₂ recovery device comprising a third rich liquid heater that heats the absorption liquid extracted from the bottom of the absorption tower using the fuel gas compressed by the second compressor as a heat source.

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