JP2011162385A - Co2 recovery method and co2 recovery apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CO<SB>2</SB>recovery method and a CO<SB>2</SB>recovery apparatus which reduce energy consumption and suppress deterioration in power generation efficiency of a process for recovering CO<SB>2</SB>by bringing a gasified gas of fuel containing carbon into contact with an absorption liquid. <P>SOLUTION: The CO<SB>2</SB>recovery method has the steps of: reacting a produced gas 1 produced by gasifying the fuel containing carbon with water vapor 2 on a catalyst to convert CO contained in the produced gas 1 to CO<SB>2</SB>; introducing the produced gas 1 into an absorption liquid heater 23 and heating the absorption liquid 6 taken out from the bottom of a CO<SB>2</SB>absorption tower 24 using the condensing heat of water contained in the produced gas 1 and the sensible heat of the produced gas 1; removing condensed water contained in the produced gas 1, then introducing the produced gas 1 into a CO<SB>2</SB>absorption tower 24 and bringing the produced gas 1 into contact with the absorption liquid 6 in the CO<SB>2</SB>absorption tower 24 to absorb CO<SB>2</SB>in the produced gas 1; and reducing the pressure of absorption liquid 6 heated by the absorption liquid heater 23 and releasing CO<SB>2</SB>gas to regenerate the absorption liquid 6 and returning the regenerated absorption liquid 6 to the CO<SB>2</SB>absorption tower 24. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a method and an apparatus for recovering CO ₂ from a gasification gas of fuel containing carbon.

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 combustion exhaust gas containing CO ₂ into contact with an aqueous alkanolamine solution or the like to absorb the CO _2, the method for recovering 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 an absorption method using an alkanolamine aqueous solution as an absorption liquid, the absorption liquid that has absorbed CO ₂ in the absorption tower is heated and regenerated using steam at about 120 ° 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.

Since carbon is mainly contained in the gasified gas in the form of CO, it is necessary to convert CO to CO ₂ in advance by a shift reaction shown in the formula (1).
CO + H ₂ O → CO ₂ + H ₂ (1)
The shift reaction proceeds by reacting a gas containing CO and water vapor at a temperature of 200 ° C. or higher in the presence of a catalyst. That is, water vapor is also used in the shift reaction. On the other hand, since the shift reaction is an exothermic reaction, it is possible to generate water vapor using the reaction heat as a heat source. However, this water vapor alone cannot cover both the regeneration of the absorbent and the shift reaction, and it is necessary to supply water vapor from the outside. Moreover, in a thermal power plant, the power transmission end efficiency is reduced by extracting water vapor originally supplied for power generation into a CO ₂ recovery process.

JP 03-193116 A JP 2006-232596 A

As described above, in the prior art, since water vapor is used as a heat source for regeneration of the absorbing liquid, a large amount of water vapor is required, and therefore a large amount of energy is required for CO ₂ recovery. Moreover, in the thermal power plant, the steam extracted from the turbine is used, and as a result, the power generation efficiency is greatly reduced.

The present invention relates to a method and apparatus for reducing energy consumption required for CO ₂ recovery in a process of recovering CO ₂ by bringing a gasification gas of fuel containing carbon such as coal and petroleum pitch into contact with an absorbing liquid. The purpose is to provide. Moreover, it aims at suppressing the fall of the power generation efficiency by extraction of the steam for power generation significantly.

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

A step of reacting a product gas generated by gasifying a fuel containing carbon and water vapor on a catalyst to convert CO contained in the product gas into CO _2; and introducing the product gas into an absorption liquid heater; Using the heat of condensation of the moisture contained in the product gas and the sensible heat of the product gas, the step of heating the absorption liquid extracted from the bottom of the CO ₂ absorption tower, and the condensation contained in the product gas Removing the water, introducing the product gas into the CO ₂ absorption tower and bringing it into contact with the absorption liquid in the CO ₂ absorption tower to absorb CO ₂ in the production gas; and the absorption liquid A step of depressurizing the absorption liquid heated by a heater, releasing CO ₂ gas to regenerate the absorption liquid, and returning it to the CO ₂ absorption tower.

In the above-mentioned CO ₂ recovery method, a step of introducing a part of the absorption liquid into a subsequent regeneration tower and heating in the process of returning the absorption liquid regenerated by releasing CO ₂ gas to the CO ₂ absorption tower And heating the absorption liquid extracted from the bottom of the CO ₂ absorption tower using a heat exchanger that uses the absorption liquid extracted from the bottom of the regeneration tower as a heat source. Also good.

Furthermore, in the CO ₂ recovery method, after the step of converting CO contained in the product gas into CO ₂ , the step of introducing the product gas into a steam generator and generating water vapor using the product gas as a heat source. And the absorption liquid heated by the absorption liquid heater is further heated by a heater using water vapor generated by the vapor generator as a heat source, and then depressurized to release CO ₂ gas, thereby reducing the absorption liquid. And a step of regenerating.

The CO ₂ recovery device according to the present invention has the following features.

In a CO ₂ recovery apparatus including a CO ₂ absorption tower having an absorption liquid that absorbs CO ₂ , a product gas generated by gasifying a fuel containing carbon and water vapor are brought into contact with each other on a catalyst, and are contained in the product gas. A shift reactor that converts CO to CO ₂ , an absorption liquid heater that heats the absorption liquid from the CO ₂ absorption tower using the product gas as a heat source, and the absorption liquid that is heated in the absorption liquid heater And a cooling tank that cools the product gas that has passed through the absorption liquid heater and a flash tank that regenerates the absorption liquid and returns it to the CO ₂ absorption tower by releasing CO ₂ gas from the absorption liquid. A steam separator for separating condensed water from the product gas that has passed through the cooler, and introducing the product gas after separating the condensed water by the steam separator to contact the absorbent. Before And the CO ₂ absorption tower for absorbing the CO ₂ contained in the generated gas into the absorption liquid. The reboiler utilizes the sensible heat of water condensation heat and the produced gas contained in the product gas, heating the absorption liquid from the CO ₂ absorption tower.

In the CO ₂ recovery apparatus, the absorption liquid regenerated in the flash tank is heated to release CO ₂ gas from the absorption liquid, and the absorption liquid heated in the regeneration tower is used as a heat source. And a heat exchanger for heating the absorption liquid from the CO ₂ absorption tower.

Further, in the above CO ₂ recovery apparatus, a steam generator that generates water vapor using the generated gas as a heat source, and the absorption liquid heated by the absorption liquid heater using the water vapor generated by the steam generator as a heat source. Further, a heater for heating may be provided.

According to the present invention, by using the generated gas to heat the absorption liquid, it is possible to reduce the amount of water vapor used in the CO ₂ recovery process, and to reduce the energy consumption necessary for CO ₂ recovery. In addition, a decrease in power generation efficiency due to extraction of power generation steam can be significantly suppressed.

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. In Example 3 of the present invention, it is a block diagram showing a structure of a CO ₂ recovery apparatus configuration omitting the steam generator and the heater. 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 product gas generated by gasifying the fuel containing carbon is reacted with water vapor on the catalyst to convert CO in the product gas into CO ₂ . Water vapor may be generated by a steam generator using the product gas self-heated by the reaction heat generated at this time as a heat source. CO ₂ in the product gas is absorbed by the absorption liquid in the absorption tower. The absorption liquid that has absorbed CO ₂ is extracted from the bottom of the absorption tower and heated by an absorption liquid heater using the generated gas as a heat source. The produced gas obtained by heating the absorption liquid is introduced into the absorption tower after the contained moisture is removed, and the contained CO ₂ is recovered. The absorption liquid heated by the absorption liquid heater may be further heated using water vapor generated by the steam generator as a heat source. Thereafter, the absorbing solution is decompressed and released by releasing the absorbed CO ₂ .

  According to the present invention, the sensible heat of the generated gas and the heat of condensation of the generated gas, which has not been conventionally used, are utilized as a heating source of the absorbing liquid by exchanging heat between the generated gas and the absorbing liquid. Can do.

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”. In Example 3, the absorption liquid regenerated by heating in the regeneration tower is referred to as “lean liquid”.

The product gas which is the subject of the present invention is a gas mainly containing CO, H ₂ , CH ₄ , CO _{2 and the} like generated when a fuel containing carbon such as coal, petroleum pitch, and heavy oil is partially oxidized.

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

An embodiment of a 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 a CO ₂ recovery method and a recovery apparatus according to the present invention is applied to a coal gasification process. FIG. 1 is a block diagram showing the configuration of the CO ₂ recovery apparatus in the present embodiment.

As shown in FIG. 1, the CO ₂ recovery apparatus in this example mainly includes a high temperature shift reactor 21a, an intermediate temperature shift reactor 21b, a low temperature shift reactor 21c, an absorption liquid heater 23, an absorption tower 24, a cooling system. And 25, 29, a steam separator 26, and a flash tank 28. Normally, a cooler is provided at least after the high temperature shift reactor 21a and the intermediate temperature shift reactor 21b, but the illustration is omitted in FIG.

Product gas 1 generated by the reaction of coal with oxygen at elevated temperatures in the gasification furnace (not shown), after dedusting and washing with water to remove the COS conversion processing and H _{2 S} for converting COS into H _{2 S} After passing through the desulfurization treatment, the steam 2 is introduced into the high temperature shift reactor 21a.

  The high temperature shift reactor 21a is filled with a shift catalyst containing Fe and Cr as main active components, and the shift reaction of the formula (1) is promoted by this catalyst. The shift reaction is an exothermic reaction, and the catalyst and product gas 1 are heated by reaction heat. In the case of a product gas obtained by gasifying coal, the CO concentration is generally as high as 20 to 60%. Therefore, when the entire amount of CO is reacted at once, the temperature of the catalyst exceeds the heat resistant temperature due to the reaction heat. Therefore, in the high temperature shift reactor 21a, only a part of CO contained in the product gas 1 is reacted.

The product gas 1 is then introduced into an intermediate temperature shift reactor 21b filled with the same catalyst as the high temperature shift reactor 21a. In medium-temperature shift reactor 21b, a part of the remaining CO contained in the product gas 1 is converted to CO _2.

The product gas 1 is further introduced into the low temperature shift reactor 21c. The low temperature shift reactor 21c is filled with a catalyst having Cu and Zn as main active components having a shift reaction promoting activity at a relatively low temperature. In the low temperature shift reactor 21c, the remaining CO is converted into CO ₂ in the product gas 1 until the desired CO concentration is reached.

  The temperature level of the shift reaction can be, for example, 250 to 450 ° C. for the high temperature shift reactor 21a, 250 to 350 ° C. for the intermediate temperature shift reactor 21b, and 250 to 270 ° C. for the low temperature shift reactor 21c.

  Next, the product gas 1 is introduced into the absorption liquid heater 23. The rich liquid 6 extracted from the bottom of the absorption tower 24 is introduced into the absorption liquid heater 23 as a cooling medium, and the product gas 1 is cooled by being deprived of heat by the rich liquid 6.

The product gas 1 is further cooled to 50 ° C. or less by the cooler 25, and after the condensed water 7 is removed by the steam separator 26, the product gas 1 is introduced into the absorption tower 24. Here, the product gas 1 comes into contact with the regenerated semi-lean liquid 13 and CO ₂ is absorbed. In this way, the purified gas 8 is obtained by removing CO ₂ from the product gas 1.

  By the way, the generated gas 1 introduced into the absorption liquid heater 23 contains water vapor that has not been used for the reaction among the water vapor 2 supplied for the shift reaction. The rich liquid 6 extracted from the bottom of the absorption tower 24 is heated by the condensation heat of the water vapor and the sensible heat of the product gas 1.

The heated rich liquid 6 is decompressed and introduced into the flash tank 28. In the flash tank 28, the absorbed CO ₂ is released from the liquid phase, the rich liquid 6 is regenerated (becomes a semi-lean liquid 13), and the emitted gas 9 containing CO ₂ is recovered.

  On the other hand, the semi-lean liquid 13 (regenerated rich liquid 6) is cooled to a predetermined temperature by the cooler 29 and then introduced into the absorption tower 24 again.

Conventionally, water vapor extracted from a turbine is used as a heat source for regeneration of the absorbing liquid, and as a result, power generation efficiency has been greatly reduced. The present invention, in the subsequent stage of the shift reaction Noting that product gas containing a large amount of steam, so far is characterized in that for heating the absorbing liquid by utilizing the condensation heat which has not been recovered, thereby CO ₂ Recovered energy can be greatly reduced.

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 coal gasification process, as in Example 1, except for the following points. That is, water vapor is generated by a steam generator using the product gas self-heated by reaction heat generated in the shift reaction as a heat source. And the absorption liquid heated with the absorption liquid heater is further heated by using the water vapor generated by the steam generator as a heat source.

FIG. 2 is a block diagram showing the configuration of the CO ₂ recovery apparatus in the present embodiment. 2, the same reference numerals as those in FIG. 1 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 high-temperature steam generator 22a, a medium-temperature, and a high-temperature shift reactor 21a, a medium-temperature shift reactor 21b, and a low-temperature shift reactor 21c are arranged at the subsequent stage. The difference is that the steam generator 22 b and the low-temperature steam generator 22 c are respectively installed, and the heaters 27 a and 27 b are installed between the absorbing liquid heater 23 and the flash tank 28.

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 product gas 1 in which a part of CO has caused a shift reaction in the high temperature shift reactor 21a is then introduced into the high temperature steam generator 22a for cooling. Here, the product gas 1 is cooled to a predetermined temperature, and at the same time, high-temperature steam 3 is generated using the heat.

Then the product gas 1 is introduced into the medium-temperature shift reactor 21b, a part of the remaining CO is cooled is introduced into the intermediate temperature steam generator 22b at the stage of conversion to CO _2. In the intermediate temperature steam generator 22b, the intermediate temperature steam 4 is generated using the generated gas 1 as a heat source.

Next, the product gas 1 is introduced into the low temperature shift reactor 21c, and the remaining CO is converted to CO ₂ until the desired CO concentration is reached, and then introduced into the low temperature steam generator 22c for cooling. In the low temperature steam generator 22c, the low temperature steam 5 is generated using the product gas 1 as a heat source. The product gas 1 after being cooled by the low-temperature steam generator 22 c is introduced into the absorption liquid heater 23.

  On the other hand, the rich liquid 6 heated by the absorption liquid heater 23 by the heat of condensation of the water vapor contained in the product gas 1 and the sensible heat of the product gas 1 is then introduced into the heater 27a, and all of the intermediate temperature steam 4 is introduced. Or it heats by using a part as a heat source. The rich liquid 6 is further introduced into the heater 27 b, heated using all or part of the high-temperature steam 3 as a heat source, decompressed, and introduced into the flash tank 28. When the rich liquid 6 is heated to a predetermined temperature by the heater 27a, the high temperature steam 3 is not supplied to the heater 27b, and the rich liquid 6 may not be heated by the heater 27b.

  By installing the heaters 27a and 27b, even if the rich liquid 6 cannot be sufficiently heated by the absorption liquid heater 23, the water vapor generated by the intermediate temperature steam generator 22b and the high temperature steam generator 22a is used as a heat source. Further heating is possible.

  In this embodiment, the heaters 27a and 27b and the two heaters are installed. However, only one of them can be installed. Alternatively, three heaters may be installed to heat the rich liquid 6 using the low temperature steam 5, the medium temperature steam 4, and the high temperature steam 3 as heat sources.

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, the CO ₂ recovery method and recovery apparatus according to the present invention, an example applied to the gasification process coal, the product gas, dedusting, washed with water, subjected to direct shift reaction, then, CO ₂ And H ₂ S are simultaneously applied to the process of removing. FIG. 3 is a block diagram showing the configuration of the CO ₂ recovery device in the present embodiment.

As shown in FIG. 3, the CO ₂ recovery apparatus in the present embodiment mainly includes a first shift reactor 30a, a second shift reactor 30b, steam generators 31a and 31b, an absorption liquid heater 23, an absorption tower. 24, coolers 25, 29, and 35, a steam separator 26, a heater 27c, a flash tank 28, a heat exchanger 33, and a regeneration tower 34. In the absorption tower 24, the absorbing solution absorbs CO ₂ and H ₂ S, and CO ₂ and H ₂ S are simultaneously removed from the product gas 1.

  The product gas 1 is introduced into the first shift reactor 30a together with the water vapor 2 after dedusting and rinsing.

The first shift reactor 30a is filled with a shift catalyst containing Co and Mo as main active components, and the reaction of the formula (1) is promoted in the presence of H ₂ S. Also in this example, the shift reaction is divided and performed so that the catalyst does not exceed the heat resistance temperature due to the reaction heat of the shift reaction. In the first shift reactor 30a, the CO contained in the product gas 1 is divided. React only part of.

  Next, the product gas 1 is introduced into the steam generator 31a and cooled. At the same time, the high temperature steam 11 is generated using the heat of the product gas 1.

Subsequently, the product gas 1 is introduced into the second shift reactor 30b filled with the same catalyst as the first shift reactor 30a, and the remaining CO is converted to CO ₂ and introduced into the steam generator 31b for cooling. Is done. In the steam generator 31b, intermediate temperature steam 12 is generated using the generated gas 1 as a heat source.

  The temperature level of the shift reaction can be, for example, 250 to 450 ° C. for the first shift reactor 30a and 250 to 350 ° C. for the second shift reactor 30b.

  Next, a method for heating the rich liquid 6 will be described. The rich liquid 6 extracted from the bottom of the absorption tower 24 is introduced into the heat exchanger 33 and heated by the heat of the high-temperature absorption liquid (lean liquid) 10 regenerated by heating in the regeneration tower 34 described later.

  Subsequently, the rich liquid 6 is introduced into the absorption liquid heater 23 and heated by the heat of the product gas 1 that has passed through the steam generator 31b. The generated gas 1 contains water vapor not used for the reaction among the water vapor 2 supplied for the shift reaction, and the rich liquid 6 is heated by the condensation heat of the water vapor and the sensible heat of the generated gas 1. Is done.

  The rich liquid 6 is further introduced into the heater 27 c, heated using all or part of the intermediate temperature steam 12 as a heat source, decompressed, and introduced into the flash tank 28.

In the flash tank 28, mainly absorbed CO ₂ is released from the liquid phase, the rich liquid 6 is regenerated (becomes a semi-lean liquid 13), and the emitted gas 9 containing CO ₂ is recovered.

  The semi-liquid 13 (the rich liquid 6 that has released the diffused gas 9) is partially cooled by the cooler 29, then introduced into the absorption tower 24, and the rest is introduced into the regeneration tower 34.

In the regeneration tower 34, the semi-lean liquid 13 is heated to 110 to 130 ° C. with water vapor, and the absorbed CO ₂ and H ₂ S are released into the gas phase as the diffused gas 9 and regenerated as the lean liquid 10.

  The lean solution 10 obtained by regenerating the semi-lean solution 13 in the regeneration tower 34 is introduced as a heating medium into the heat exchanger 33 while maintaining a high temperature as described above, and is used for heating the rich solution 6. Thereafter, after being cooled to a predetermined temperature by the cooler 35, it is introduced into the absorption tower 24.

On the other hand, the product gas 1 cooled by heat exchange with the rich liquid 6 by the absorption liquid heater 23 is further cooled to 50 ° C. or less by the cooler 25, and the condensed water 7 is removed by the steam separator 26. Thereafter, the product gas 1 is introduced into the absorption tower 24, CO ₂ and H ₂ S are removed, and a purified gas 8 is obtained.

As described above, in this embodiment, H ₂ S removal and CO ₂ recovery, which are conventionally performed individually, can be performed simultaneously. Further, the rich liquid 6 before being introduced into the flash tank 28 is heated using the condensation heat of water vapor contained in the product gas 1, the sensible heat of the product gas 1, and the high-temperature lean liquid 10 extracted from the regeneration tower. Can do. Thereby, the water vapor | steam generated using the reaction heat | fever of shift reaction can be mainly used for electric power generation, and the fall of electric power generation efficiency can be suppressed.

In the present embodiment, as in the second embodiment, the steam generators 31a and 31b generate the high-temperature steam 11 and the intermediate-temperature steam 12, and the rich liquid 6 is heated by the heater 27c using the intermediate-temperature steam 12 as a heat source. However, like the first embodiment, the steam generators 31a and 31b and the heater 27c can be omitted. FIG. 4 is a block diagram showing the configuration of the CO ₂ recovery apparatus having such a configuration.

  In the case of the configuration shown in FIG. 4, the heat of condensation of the product gas 1, the sensible heat of the product gas 1, the sensible heat of the product gas 1, and the high-temperature lean liquid 10 are used without using the steam generated using the reaction heat of the shift reaction. Only the rich liquid 6 is heated. In this case, water vapor generated by using the reaction heat of the shift reaction can be used for power generation, and the reduction in power generation efficiency can be further suppressed.

A fourth embodiment of the CO ₂ recovery method and recovery apparatus according to the present invention will be described with reference to FIG. In the fourth embodiment, an example of an operation control method for heating the rich liquid by collecting the condensation heat will be described for the CO ₂ recovery apparatus having the same configuration as that of the second embodiment.

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. 2 denote the same or common elements as those in FIG. The CO ₂ recovery apparatus of the present embodiment has the same configuration as that of the second embodiment, but in FIG. 5, additional components necessary for operation control when recovering the condensation heat and heating the rich liquid 6 are added. Described.

  The absorption liquid heater 23 is designed so that the heat of condensation of moisture contained in the product gas 1 can be recovered.

  A thermometer 51 is installed at the inlet of the absorption liquid heater 23 in the flow path of the product gas 1 to measure the temperature of the product gas 1. A thermometer 53 is also installed at the outlet of the cooler 25. Thermometers 56 and 57 are provided at the inlets of the intermediate temperature shift reactor 21b and the low temperature shift reactor 21c, respectively.

  The flow rate of the cooling water supplied to the cooler 25 can be adjusted by the flow rate adjustment valve 64. Further, the flow rates of the boiler feed waters 14a, 14b, and 14c supplied to the high temperature steam generator 22a, the medium temperature steam generator 22b, and the low temperature steam generator 22c can be adjusted by flow rate control valves 67, 68, and 63, respectively. .

  In the flow path of the rich liquid 6, a thermometer 52 is installed at the outlet of the absorbing liquid heater 23, a thermometer 54 is installed at the outlet of the heater 27a, and a thermometer 55 is installed at the outlet of the heater 27b. The flow rate of the intermediate temperature steam 4 a that is separated from the intermediate temperature steam 4 generated from the intermediate temperature steam generator 22 b and supplied to the heater 27 a can be adjusted by the flow rate control valve 65. The flow rate of the high-temperature steam 3a separated from the high-temperature steam 3 generated from the high-temperature steam generator 22a and supplied to the heater 27b can be adjusted by the flow rate control valve 66. It is also possible to adjust the flow rate control valve 65 to supply, for example, the entire amount of the intermediate temperature steam 4 to the heater 27a as the intermediate temperature steam 4a.

  The temperature of the rich liquid 6 after passing through the absorption liquid heater 23 is measured by a thermometer 52. When this temperature does not satisfy the predetermined reference temperature required for the rich liquid 6 to be regenerated in the flash tank 28, the intermediate temperature steam supplied to the heater 27a is increased by increasing the opening degree of the flow control valve 65. Increase the flow rate of 4a. If the predetermined temperature is not yet reached even when the entire amount of the intermediate-temperature steam 4 is supplied to the heater 27a, the flow rate of the high-temperature steam 3a supplied to the heater 27b is increased by increasing the opening of the flow control valve 66. The temperature of the rich liquid 6 finally measured by the thermometer 55 is adjusted to a predetermined temperature. In this way, the amount and temperature of the water vapor that heats the rich liquid 6 can be controlled to keep the temperature of the rich liquid 6 at a predetermined temperature.

  On the other hand, when the temperature of the product gas 1 measured by the thermometer 51 exceeds the reference temperature, the boiler feed water 14c supplied to the low-temperature steam generator 22c by increasing the opening degree of the flow control valve 63. Increase the flow rate. Thereby, the quantity of the low temperature steam 5 generated with the low temperature steam generator 22c can be increased, and the temperature rise of the product gas 1 can be prevented. In this way, the temperature of the product gas 1 introduced into the absorption liquid heater 23 can be maintained at a predetermined temperature.

  As described above, the temperature of the product gas 1 can be adjusted when the heat of condensation of the product gas 1 is recovered.

  In addition, the temperature of the intermediate temperature shift reactor 21b and the low temperature shift reactor 21c can be adjusted. The flow rates of the boiler feed waters 14a and 14b supplied to the high-temperature steam generator 22a and the intermediate-temperature steam generator 22b are adjusted so that the temperature of the product gas 1 measured by the thermometers 56 and 57 becomes a predetermined temperature. And 68 respectively.

  DESCRIPTION OF SYMBOLS 1 ... Production gas, 2 ... Water vapor, 3 ... High temperature steam, 3a ... Prepared high temperature steam, 4 ... Medium temperature steam, 4a ... Prepared intermediate temperature steam, 5 ... Low temperature steam, 6 ... Rich liquid, 7 ... Condensation Water, 8 ... Purified gas, 9 ... Stripped gas, 10 ... Lean liquid, 11 ... High temperature steam, 12 ... Medium temperature steam, 13 ... Semi-lean liquid, 14a, 14b, 14c ... Boiler feed water, 21a ... High temperature shift reactor, 21b ... Intermediate temperature shift reactor, 21c ... Low temperature shift reactor, 22a ... High temperature steam generator, 22b ... Medium temperature steam generator, 22c ... Low temperature steam generator, 23 ... Absorption liquid heater, 24 ... Absorption tower, 25, 29, 35 ... cooler, 26 ... steam separator, 27a, 27b, 27c ... heater, 28 ... flash tank, 30a ... first shift reactor, 30b ... second shift reactor, 31a, 31b ... steam generator, 33 ... heat exchanger, 34 ... again Tower, 51,52,53,54,55,56,57 ... thermometer, 61,62,63,64,65,66,67,68 ... flow control valve.

Claims (8)

In a method for recovering CO ₂ from a product gas generated by gasifying a fuel containing carbon,
Reacting the product gas with water vapor on a catalyst to convert CO contained in the product gas into CO ₂ ;
The generated gas is introduced into an absorption liquid heater, and the absorption liquid extracted from the bottom of the CO ₂ absorption tower is heated using the heat of condensation of moisture contained in the generated gas and the sensible heat of the generated gas. And a process of
Following removal of condensed water contained in the product gas, introducing the product gas to the CO ₂ absorption tower, a CO ₂ absorption solution the product gas is contacted with in the CO ₂ absorption tower Absorbing, and
Reducing the pressure of the absorption liquid heated by the absorption liquid heater, releasing CO ₂ gas to regenerate the absorption liquid, and returning it to the CO ₂ absorption tower;
A CO ₂ recovery method comprising: The CO ₂ recovery method according to claim 1, wherein
In the process of returning the absorption liquid regenerated by releasing CO ₂ gas to the CO ₂ absorption tower, a part of the absorption liquid is further introduced into a subsequent regeneration tower and heated;
Heating the absorption liquid extracted from the bottom of the CO ₂ absorption tower using a heat exchanger having the absorption liquid extracted from the bottom of the regeneration tower as a heat source;
CO ₂ recovery method having The CO ₂ recovery method according to claim 1 or 2,
After the step of converting CO contained in the product gas into CO ₂ , introducing the product gas into a steam generator and generating water vapor using the product gas as a heat source;
The absorption liquid heated by the absorption liquid heater is further heated by a heater using water vapor generated by the steam generator as a heat source and then depressurized to release CO ₂ gas to regenerate the absorption liquid. Process,
CO ₂ recovery method having The CO ₂ recovery method according to claim 3,
When the temperature of the product gas at the inlet of the absorption liquid heater is lower than a predetermined reference temperature, the amount of the water vapor generated by the steam generator is reduced, and when the temperature is higher than the reference temperature, the steam is generated. A CO ₂ recovery method for increasing the amount of water vapor generated by a generator. The CO ₂ recovery method according to claim 3,
A CO ₂ recovery method for increasing at least one of an amount and a temperature of the water vapor serving as a heat source of the heater when the temperature of the absorbing liquid that has passed through the absorbing liquid heater is lower than a predetermined reference temperature. In the CO ₂ recovery apparatus having a CO ₂ absorption tower having an absorbent that absorbs CO _2,
A shift reactor for converting CO contained in the product gas into CO ₂ by bringing a product gas generated by gasifying a fuel containing carbon into contact with water vapor on a catalyst;
An absorption liquid heater for heating the absorption liquid from the CO ₂ absorption tower using the generated gas as a heat source;
A flash tank that regenerates the absorption liquid and returns it to the CO ₂ absorption tower by depressurizing the absorption liquid heated in the absorption liquid heater and releasing CO ₂ gas from the absorption liquid;
A cooler that cools the product gas that has passed through the absorption liquid heater;
A steam separator for separating condensed water from the product gas that has passed through the cooler;
The CO ₂ absorption tower that introduces the generated gas after separating condensed water with the steam separator and makes it contact with the absorbing liquid, and absorbs CO ₂ contained in the generated gas into the absorbing liquid;
With
The reboiler utilizes the sensible heat of the product gas and condensation heat of water contained in the product gas, CO _2, characterized by heating the absorption liquid from the CO ₂ absorption tower Recovery device. The CO ₂ recovery device according to claim 6,
A regeneration tower for releasing CO ₂ gas from the absorbing liquid by heating the absorbing liquid regenerated in the flash tank;
Using the absorption liquid heated in the regeneration tower as a heat source, a heat exchanger for heating the absorption liquid from the CO ₂ absorption tower,
A CO ₂ recovery device. The CO ₂ recovery device according to claim 6 or 7,
A steam generator for generating water vapor using the product gas as a heat source;
A heater that further heats the absorption liquid heated by the absorption liquid heater using water vapor generated by the vapor generator as a heat source;
A CO ₂ recovery device.

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