JP7309983B1 - Carbon dioxide recovery device and carbon dioxide recovery method - Google Patents

Abstract

A carbon dioxide recovery device capable of keeping energy costs low is provided. A carbon dioxide recovery apparatus (1A) for absorbing carbon dioxide contained in a carbon dioxide-containing gas into an absorbing liquid and heating the absorbing liquid that has absorbed the carbon dioxide to diffuse and recover the carbon dioxide. A processing tower 10 containing the liquid and a heater 65A for heating the absorbing liquid to 40 to 90° C. at which carbon dioxide can be diffused by heat exchange with the exhaust gas are provided. [Selection drawing] Fig. 1

Description

Article 30, Paragraph 2 of the Patent Law applies Publisher name: Public Interest Incorporated Association National Urban Cleaning Council Publication name: Urban Cleaning, Vol. 75, No. 365, p. Day

The present invention provides a carbon dioxide recovery apparatus and a carbon dioxide recovery method for absorbing carbon dioxide contained in a carbon dioxide-containing gas into an absorption liquid and heating the absorption liquid that has absorbed the carbon dioxide to diffuse and recover the carbon dioxide. Regarding.

As a method for recovering carbon dioxide, for example, a chemical absorption method utilizing reactive absorption by a basic compound is known. In the chemical absorption method, the carbon dioxide contained in the gas is brought into contact with an amine-based absorbing liquid in an absorption tower, the absorbing liquid that has absorbed carbon dioxide is sent from the absorption tower to the regeneration tower, and the carbon dioxide is removed from the absorption liquid in the regeneration tower. A carbon dioxide recovery device that diffuses and recovers is known (see, for example, Patent Document 1).

In the carbon dioxide recovery apparatus described in Patent Document 1, a reboiler that uses steam as a heat source is provided at the bottom of the regeneration tower, and the reboiler heats the absorbent to dissipate carbon dioxide from the absorbent. .

JP-A-11-267442

In the carbon dioxide recovery device described in Patent Document 1, carbon dioxide is released by heating with a reboiler using steam as a heat source, so the thermal energy required to generate steam and the thermal energy required to raise the temperature of the absorbent , heat energy required to dissipate carbon dioxide from the absorbing liquid, heat energy for compensating for heat loss due to evaporation of water in the absorbing liquid, and the like. Therefore, a large amount of energy is required to dissipate the absorbed carbon dioxide, resulting in an increase in energy cost.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a carbon dioxide recovery apparatus and a carbon dioxide recovery method that can keep energy costs low.

The characteristic configuration of the carbon dioxide capture device according to the present invention for solving the above problems is as follows:
A carbon dioxide recovery device that absorbs carbon dioxide contained in a carbon dioxide-containing gas into an absorption liquid and heats the absorption liquid that has absorbed the carbon dioxide to diffuse and recover the carbon dioxide,
a treatment tower containing the absorbing liquid;
a heater that heats the absorbent to 40 to 90° C. where the carbon dioxide can be diffused by heat exchange with the exhaust gas;
It is to prepare

According to the carbon dioxide recovery apparatus of this configuration, an absorbent capable of dissipating the absorbed carbon dioxide at 40 to 90° C. is used, and the absorbent is heated by the heater through heat exchange with the exhaust gas. Here, the exhaust gas is usually discharged into the atmosphere and discarded, and the exhaust gas temperature at the time of disposal is about 140 to 170°C. In this way, since there is a sufficient temperature difference between the temperature (40 to 90° C.) at which the carbon dioxide of the absorbent can be diffused and the exhaust gas temperature (140 to 170° C.) at the time of disposal, the absorbent can be It can be heated to 40 to 90° C. by a heater through heat exchange with the exhaust gas, and carbon dioxide can be diffused and recovered from the absorbent in the treatment tower. Therefore, carbon dioxide can be recovered from the waste heat of the exhaust gas which is normally discharged into the atmosphere and discarded, and the energy cost can be kept low by the effective use of the waste heat.

In the carbon dioxide recovery device according to the present invention,
The treatment tower includes an absorption tower that absorbs the carbon dioxide into the absorption liquid, and a regeneration tower that dissipates the carbon dioxide from the absorption liquid that has absorbed the carbon dioxide,
The absorption tower and the regeneration tower are connected so that the absorption liquid is circulated between the absorption tower and the regeneration tower, and the absorption liquid supplied from the absorption tower to the regeneration tower is heated. Preferably, the heater is arranged to.

According to the carbon dioxide recovery apparatus of this configuration, the absorption and desorption of carbon dioxide are continuously performed by the absorption tower and the regeneration tower, and the absorbent supplied from the absorption tower to the regeneration tower uses the waste heat of the exhaust gas as a heat source. Since it is heated by the heater, it is possible to improve the recovery efficiency of carbon dioxide while keeping the energy required to dissipate the absorbed carbon dioxide low.

In the carbon dioxide recovery device according to the present invention,
The treatment tower includes an absorption tower that absorbs the carbon dioxide into the absorption liquid, and a regeneration tower that dissipates the carbon dioxide from the absorption liquid that has absorbed the carbon dioxide,
The absorption tower and the regeneration tower are connected so that the absorption liquid is circulated between the absorption tower and the regeneration tower, and the absorption liquid is circulated between the regeneration tower and the heater. It is preferable that the regeneration tower and the heater are connected so as to be connected.

According to the carbon dioxide recovery device of this configuration, the absorption and desorption of carbon dioxide are continuously performed by the absorption tower and the regeneration tower, and the absorbent circulated between the regeneration tower and the heater is used as waste gas. Since it is heated by a heater that uses heat as a heat source, it is possible to improve the recovery efficiency of carbon dioxide while keeping the energy required to dissipate the absorbed carbon dioxide low.

In the carbon dioxide recovery device according to the present invention,
It is preferable to provide decompression means for decompressing the inside of the regeneration tower.

According to the carbon dioxide recovery device of this configuration, the synergistic effect of the heating of the absorbent by the heater and the decompression of the absorbent by the decompression means can further improve the efficiency of recovering carbon dioxide, and at the same time, reduce carbon dioxide. Absorbent liquid can be regenerated to a state where it can be fully absorbed.

In the carbon dioxide recovery device according to the present invention,
The heater includes a heat transfer tube in which the exhaust gas is in contact with the outer surface and a heat medium is flowed inside,
It is preferable that the outer surface temperature of the heat transfer tube is set higher than the dew point of the exhaust gas.

According to the carbon dioxide recovery device of this configuration, the temperature of the outer surface of the heat transfer tube is set to be higher than the dew point of the exhaust gas, so that corrosive components do not evaporate near the outer surface of the heat transfer tube due to contact with the exhaust gas. The atmosphere becomes dominant, and it is possible to prevent the generation of droplets containing corrosive components due to dew condensation. Therefore, there is an advantage that corrosion measures (for example, anti-corrosion coating, fluororesin lining, etc.) for the casing of the heater can be eliminated or simplified.

In the carbon dioxide recovery device according to the present invention,
The heater includes a heat transfer tube in which the exhaust gas is in contact with the outer surface and a heat medium is flowed inside,
The heat transfer tubes are made of a corrosion-resistant material,
It is preferable that the outer surface temperature of the heat transfer tube is set to be equal to or lower than the dew point of the exhaust gas.

According to the carbon dioxide recovery device of this configuration, heat can be recovered to a temperature below the dew point using a corrosion-resistant material, so the amount of heat medium (steam, etc.) used in the carbon dioxide recovery device can be greatly reduced. can be reduced. Furthermore, by performing heat recovery to a temperature lower than the condensation temperature of moisture in the exhaust gas, the thermal energy corresponding to the latent heat of water can also be recovered, resulting in a greater effect.

Next, the characteristic configuration of the carbon dioxide recovery method according to the present invention for solving the above problems is as follows:
an absorption step of absorbing carbon dioxide contained in the carbon dioxide-containing gas into an absorption liquid;
a recovery step of heating the absorption liquid that has absorbed the carbon dioxide to a temperature of 40 to 90° C. at which the carbon dioxide can be dissipated by heat exchange with the exhaust gas to diffuse and recover the carbon dioxide;
to include

According to the carbon dioxide recovery method of this configuration, an absorbent that can dissipate the carbon dioxide absorbed in the absorption step at 40 to 90 ° C. is used, and the absorbent is heated in the recovery step by heat exchange with the exhaust gas. . Here, the exhaust gas is usually discharged into the atmosphere and discarded, and the exhaust gas temperature at the time of disposal is about 140 to 170°C. In this way, since there is a sufficient temperature difference between the temperature (40 to 90 ° C.) at which the carbon dioxide of the absorbent can be diffused and the exhaust gas temperature (140 to 170 ° C.) at the time of disposal, in the recovery process The absorbing liquid can be heated to 40 to 90° C. by heat exchange with the exhaust gas, and carbon dioxide can be diffused and recovered from the absorbing liquid. Therefore, carbon dioxide can be recovered from the waste heat of the exhaust gas which is normally discharged into the atmosphere and discarded, and the energy cost can be kept low by the effective use of the waste heat.

FIG. 1 is a block diagram showing a schematic configuration of a carbon dioxide capture device according to a first embodiment of the present invention. FIG. 2 is a block diagram showing a schematic configuration of a carbon dioxide capture device according to a second embodiment of the invention. FIG. 3 is a block diagram showing a schematic configuration of a carbon dioxide capture device according to a third embodiment of the invention. FIG. 4 is a block diagram showing a schematic configuration of a carbon dioxide recovery device according to a fourth embodiment of the invention. FIG. 5 is a block diagram showing a schematic configuration of a carbon dioxide capture device according to a fifth embodiment of the invention. FIG. 6 is a block diagram showing a schematic configuration of a carbon dioxide capture device according to a sixth embodiment of the present invention. FIG. 7 is a block diagram showing a schematic configuration of a carbon dioxide recovery device according to a seventh embodiment of the invention.

The present invention will be described below with reference to the drawings. In the following embodiments, an example of recovering carbon dioxide from exhaust gas treated by an exhaust gas treatment facility in a biomass power generation facility will be described. However, the present invention is not intended to be limited to the embodiments described below or the configurations described in the drawings. The biomass fuel to be burned in the biomass power generation facility is bio-derived fuel extracted from natural organic resources such as plants and agricultural products other than fossil fuels. Specifically, as biomass fuels, for example, waste wood, thinned wood, driftwood, grass, household waste, sludge, livestock manure, energy crops (crops), recycled fuel (pellets and chips) made from these raw materials etc.

[First Embodiment]
FIG. 1 is a block diagram showing a schematic configuration of a carbon dioxide recovery device 1A according to the first embodiment of the present invention. The carbon dioxide recovery device 1A shown in FIG. It is configured to dissipate and recover carbon dioxide by heating.

<Exhaust gas treatment equipment>
The exhaust gas treatment equipment 200 is equipment including a bag filter, an induced draft fan, and the like. In the exhaust gas treatment equipment 200, the exhaust gas generated by the combustion of the biomass fuel in the combustion furnace is introduced into the bag filter by the induction action of the induced draft fan and is subjected to dust removal.

<Absorbing liquid>
The absorption liquid is not particularly limited as long as it can dissipate the absorbed carbon dioxide at 40 to 90 ° C., for example, JP-A-2021-154236 and JP-A-2021-154237. A non-aqueous carbon dioxide absorbing liquid disclosed in the publication can be used.

<Carbon dioxide recovery device>
As shown in FIG. 1, the carbon dioxide recovery device 1A includes a treatment tower 10 containing an absorbent.

<Treatment tower>
The treatment tower 10 includes an absorption tower 3 that absorbs carbon dioxide into an absorption liquid, and a regeneration tower 5 that releases carbon dioxide from the absorption liquid that has absorbed carbon dioxide.

<Absorption tower>
The absorption tower 3 is not particularly limited as long as it has a structure that allows the absorption liquid to absorb carbon dioxide, and a known structure can be used. In the absorption tower 3, a gas inlet 11 is provided at the bottom, a gas outlet 13 is provided at the top, an absorbent outlet 15 is provided at the bottom, and an absorbent inlet 17 is provided at the top. ing.

<Regeneration Tower>
The regeneration tower 5 is not particularly limited as long as it has a structure capable of diffusing carbon dioxide from the absorption liquid that has absorbed carbon dioxide, and a known structure can be used. In the regeneration tower 5, an absorbent inlet 21 is provided at the top, an absorbent outlet 23 is provided at the bottom, and a gas outlet 25 is provided at the top.

The gas inlet 11 of the absorption tower 3 and the exhaust gas treatment equipment 200 are connected by an exhaust gas supply pipe 31 . A gas discharge pipe 33 is connected to the gas discharge port 13 of the absorption tower 3 . A gas discharge pipe 35 is connected to the gas discharge port 25 of the regeneration tower 5 .

The absorbent outlet 15 of the absorption tower 3 and the absorbent inlet 21 of the regeneration tower 5 are connected by an absorbent supply pipe 41 . The absorbent inlet 17 of the absorption tower 3 and the absorbent outlet 23 of the regeneration tower 5 are connected by an absorbent reflux pipe 43 . Thus, the absorption tower 3 and the regeneration tower 5 are connected by the absorption liquid supply pipe 41 and the absorption liquid reflux pipe 43 so that the absorption liquid is circulated between the absorption tower 3 and the regeneration tower 5 .

A pretreatment facility 45 is arranged in the middle of the exhaust gas supply pipe 31 . The pretreatment equipment 45 is configured to wash the exhaust gas in a wet process through gas-liquid contact between cleaning water to which chemicals are added and the exhaust gas. In the pretreatment equipment 45, most of the harmful substances such as sulfur oxides, acid gas components, dioxins, and heavy metals in the exhaust gas are separated and removed from the exhaust gas by washing water, and the exhaust gas is suitable for absorbing carbon dioxide. cooled to room temperature. In the pretreatment equipment 45, the cleaning water whose pH has become weakly acidic after spraying may be neutralized and then sprayed again to remove acid gas by gas-liquid contact.

A pump 51 is interposed in the absorbent supply pipe 41 . The absorbent contained in the absorption tower 3 is supplied to the regeneration tower 5 through the absorbent supply pipe 41 by the operation of the pump 51 . A pump 53 is interposed in the absorbent reflux pipe 43 . The absorbent contained in the regeneration tower 5 is circulated to the absorption tower 3 through the absorbent reflux pipe 43 by the operation of the pump 53 .

<Decompression means>
A pump 55 that functions as pressure reducing means of the present invention is interposed in the gas discharge pipe 35 . The pressure inside the regeneration tower 5 is reduced by the operation of the pump 55 .

The carbon dioxide recovery apparatus 1A further includes a heater 60 for raising the temperature of the absorbent supplied from the absorption tower 3 to the regeneration tower 5, and a heater 65A for heating the absorbent heated by the heater 60. ing.

<heater>
The temperature riser 60 includes a first heat exchanger 71 interposed in the absorbent supply pipe 41 and a second heat exchanger 72 interposed in the absorbent reflux pipe 43 . In the temperature raising device 60 , a heat medium (for example, air or water) flows between the first heat exchanger 71 and the second heat exchanger 72 , so that the absorbent flowing through the absorbent supply pipe 41 is heated. and the absorbent flowing through the absorbent reflux pipe 43 , and the absorbent flowing through the absorbent supply pipe 41 is heated.

<Heater>
The heater 65A includes a third heat exchanger 73 interposed downstream of the first heat exchanger 71 in the absorbent supply pipe 41 and upstream of the exhaust gas flow of the pretreatment equipment 45 in the exhaust gas supply pipe 31. and a fourth heat exchanger 74 interposed. In the heater 65A, a heat medium (for example, air, water, etc.) flows between the third heat exchanger 73 and the fourth heat exchanger 74, so that the absorbent flowing through the absorbent supply pipe 41 is , heat exchange is performed with the exhaust gas flowing through the exhaust gas supply pipe 31, and the absorbent flowing through the absorbent supply pipe 41 after being heated by the temperature riser 60 (first heat exchanger 71) is heated. is configured as

The fourth heat exchanger 74 is configured with a heat transfer tube in which the exhaust gas contacts the outer surface and the heat transfer medium flows inside. In the fourth heat exchanger 74, the outer surface of the heat transfer tube that contacts the exhaust gas in the heat transfer tube even under the condition that the amount of exhaust gas is the smallest and/or the temperature of the exhaust gas is the lowest in the fluctuating range of the amount of exhaust gas and the temperature of the exhaust gas. The length, diameter, thickness, material, etc. of the heat transfer tubes are set so that the temperature is higher than the dew point. Here, the dew point is the temperature at which sulfuric acid gas turns into sulfuric acid and condenses.

In the fourth heat exchanger 74, the temperature of the outer surface of the heat transfer tube is set to be higher than the dew point of the exhaust gas. atmosphere, and the generation of droplets containing corrosive components due to dew condensation can be prevented. Therefore, there is an advantage that corrosion measures (for example, anti-corrosion coating, fluorine resin lining, etc.) for the casing of the fourth heat exchanger 74 can be eliminated or simplified.

Materials for the heat transfer tubes in the fourth heat exchanger 74 include, for example, corrosion-resistant metals such as stainless steel, Hastelloy, and Inconel, and non-metallic materials such as fluorine resin. Examples of fluororesins include polytetrafluoroethylene (PTFE), tetrafluoroethylene/perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene/hexafluoropropylene copolymer (FEP), tetrafluoroethylene/ethylene copolymer polymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and the like.

The thickness of the fluororesin tube used as the heat transfer tube is preferably 0.5 to 2.0 mm, more preferably 1.0 to 1.5 mm. If the thickness of the fluororesin tube is within the above numerical range, the high heat transfer performance of the heat transfer tube can be maintained.

The outer diameter of the fluororesin tube is preferably φ10 to φ100 mm, more preferably φ18 to φ30 mm, when the heat medium is gas. Further, when the heat medium is liquid, the diameter is preferably φ4 to φ15 mm, more preferably φ8 to φ13 mm. If the outer diameter is within the above numerical range, the heat transfer tube is less likely to be affected by pressure loss and has good pressure resistance.

In the carbon dioxide recovery apparatus 1A configured as described above, the absorption step in the absorption tower 3 and the recovery step in the regeneration tower 5 are continuously performed, and the temperature raising step is performed when the recovery step is performed. and a heating step are performed.

<Absorption process>
The dust-removed exhaust gas sent out from the exhaust gas treatment equipment 200 is sent to the pretreatment equipment 45, and after the harmful substances are removed by the pretreatment equipment 45, it is sent into the absorption tower 3 through the exhaust gas supply pipe 31. . The flue gas sent into the absorption tower 3 comes into gas-liquid contact with the absorption liquid. Thereby, the carbon dioxide contained in the exhaust gas is absorbed by the absorbent. The treated liquid that has absorbed carbon dioxide is stored in the lower part of the absorption tower 3 . On the other hand, the exhaust gas from which carbon dioxide has been removed is discharged outside the absorption tower 3 through the gas discharge pipe 33 . "Exhaust gas from which carbon dioxide has been removed" refers to both "exhaust gas from which all of the contained carbon dioxide has been removed" and "exhaust gas from which part of the contained carbon dioxide has been removed." It includes

<Temperature raising process, heating process>
The absorbent stored in the lower part of the absorption tower 3 is supplied to the regeneration tower 5 through the absorbent supply pipe 41 by the operation of the pump 51 . At this time, the absorbent flowing through the absorbent supply pipe 41 from the absorber 3 toward the regeneration tower 5 is heated by the heater 60 (first heat exchanger 71), and then heated to 40 to 90 by the heater 65A. °C. In this way, by heating the treatment liquid in the stage prior to carrying out the regeneration process, which will be described later, the efficiency of carbon dioxide diffusion in the regeneration process can be improved.

<Regeneration process>
The inside of the regeneration tower 5 is decompressed by a pump 55 functioning as decompression means (decompression step). The absorbent heated by the heater 65A is supplied to the interior of the regeneration tower 5 under reduced pressure. In the regeneration tower 5, the synergistic effect of heating the absorbent by the heater 65A and reducing the pressure of the absorbent by the depressurizing means (pump 55) efficiently diffuses carbon dioxide from the absorbent. In this way, the recovery efficiency of carbon dioxide can be further improved, and the absorbent can be regenerated into a state in which carbon dioxide can be sufficiently absorbed.

In the regeneration step, the absorbent in the regeneration tower 5, which has been regenerated to a state where carbon dioxide can be sufficiently absorbed by the diffusion of carbon dioxide, is circulated to the absorption tower 3 through the absorbent reflux pipe 43 by the operation of the pump 53. be done. At this time, between the first heat exchanger 71 and the second heat exchanger 72, the absorbent flowing through the absorbent supply pipe 41 from the absorption tower 3 toward the regeneration tower 5 and the absorption tower 3 from the regeneration tower 5 Heat is exchanged with the absorbing liquid flowing through the absorbing liquid reflux pipe 43 toward . As a result, the absorbent flowing through the absorbent supply pipe 41 from the absorption tower 3 toward the regeneration tower 5 serves as a source of cold heat, and the absorbent flowing through the absorbent reflux pipe 43 from the regeneration tower 5 toward the absorption tower 3 becomes the second 2 is cooled by heat exchanger 72 .

According to the carbon dioxide recovery device 1A of the first embodiment, an absorbent capable of dissipating the absorbed carbon dioxide at 40 to 90° C. is used, and the absorbent is heated by the heater 65A through heat exchange with the exhaust gas. be. Here, the exhaust gas is usually discharged into the atmosphere and discarded, and the exhaust gas temperature at the time of disposal is about 140 to 170°C. In this way, since there is a sufficient temperature difference between the temperature (40 to 90° C.) at which the carbon dioxide of the absorbent can be diffused and the exhaust gas temperature (140 to 170° C.) at the time of disposal, the absorbent can be It can be heated to 40 to 90.degree. Therefore, carbon dioxide can be recovered from the waste heat of the exhaust gas which is normally discharged into the atmosphere and discarded, and the energy cost can be kept low by the effective use of the waste heat.

Further, according to the carbon dioxide recovery apparatus 1A, the absorption and desorption of carbon dioxide are continuously performed by the absorption tower 3 and the regeneration tower 5, and the absorbent supplied from the absorption tower 3 to the regeneration tower 5 is used as the exhaust gas. Since it is heated by the heater 65A that uses waste heat as a heat source, it is possible to improve the recovery efficiency of carbon dioxide while keeping the energy required to dissipate the absorbed carbon dioxide low.

[Second embodiment]
FIG. 2 is a block diagram showing a schematic configuration of a carbon dioxide recovery device 1B according to a second embodiment of the invention. In the second embodiment, the same or similar parts as those in the first embodiment are denoted by the same reference numerals in the drawings, and detailed descriptions thereof are omitted. I will explain.

In the carbon dioxide recovery device 1B of the second embodiment, the heater 65B has a reboiler 80 attached to the regeneration tower 5. As shown in FIG. An absorbent withdrawal pipe 81 and an absorbent return pipe 83 are connected to the reboiler 80 . The absorbent discharge pipe 81 is arranged so as to be connected to the reboiler 80 in a form branched from the absorbent reflux pipe 43 . The absorbent return pipe 83 is arranged to connect the reboiler 80 and the lower part of the regeneration tower 5 . Further, the reboiler 80 is connected so that dust-removed flue gas sent out from the flue gas treatment facility 200 is introduced and discharged. In the heater 65B, heat exchange is performed between the absorbing liquid introduced into the reboiler 80 through the absorbing liquid discharge pipe 81 and the exhaust gas introduced into the reboiler 80 through the exhaust gas supply pipe 31, thereby removing the exhaust gas. The absorbing liquid that has absorbed heat is returned to the inside of the regeneration tower 5 via the absorbing liquid return pipe 83 , thereby heating the absorbing liquid in the regeneration tower 5 .

In the carbon dioxide recovery apparatus 1B configured as described above, the absorption step in the absorption tower 3 and the recovery step in the regeneration tower 5 are continuously performed, and the temperature raising step is performed when the recovery step is performed. and a heating step are performed.

<Absorption process>
The dust-removed exhaust gas sent out from the exhaust gas treatment equipment 200 is sent to the pretreatment equipment 45 via the reboiler 80, and after the harmful substances are removed in the pretreatment equipment 45, the exhaust gas is sent through the exhaust gas supply pipe 31 to the absorption tower. It is sent to the inside of 3. The flue gas sent into the absorption tower 3 comes into gas-liquid contact with the absorption liquid. Thereby, the carbon dioxide contained in the exhaust gas is absorbed by the absorbent. The treated liquid that has absorbed carbon dioxide is stored in the lower part of the absorption tower 3 . On the other hand, the exhaust gas from which carbon dioxide has been removed is discharged outside the absorption tower 3 through the gas discharge pipe 33 .

<Temperature raising process, heating process>
The absorbent stored in the lower part of the absorption tower 3 is supplied to the regeneration tower 5 through the absorbent supply pipe 41 by the operation of the pump 51 . At this time, the absorbent flowing through the absorbent supply pipe 41 from the absorption tower 3 toward the regeneration tower 5 is heated by the temperature riser 60 (first heat exchanger 71) and then sent into the regeneration tower 5. be The absorbent inside the regeneration tower 5 is heated to 40 to 90° C. by the heater 65B. In this way, by heating the treatment liquid in the stage prior to carrying out the regeneration process, which will be described later, the efficiency of carbon dioxide diffusion in the regeneration process can be improved.

<Regeneration process>
The inside of the regeneration tower 5 is decompressed by a pump 55 functioning as decompression means (decompression step). In the regeneration tower 5, carbon dioxide is efficiently diffused from the absorbent due to the synergistic effect of heating the absorbent by the heater 65B and reducing the pressure of the absorbent by the pressure reducing means (pump 55). In this way, the recovery efficiency of carbon dioxide can be further improved, and the absorbent can be regenerated into a state in which carbon dioxide can be sufficiently absorbed.

In the regeneration step, the absorbent inside the regeneration tower 5, which has been regenerated to a state where carbon dioxide can be sufficiently absorbed by diffusion of carbon dioxide, is supplied to the absorption tower 3 through the absorbent reflux pipe 43 by the operation of the pump 53. be circulated. At this time, between the first heat exchanger 71 and the second heat exchanger 72, the absorbent flowing through the absorbent supply pipe 41 from the absorption tower 3 toward the regeneration tower 5 and the absorption tower 3 from the regeneration tower 5 Heat is exchanged with the absorbing liquid flowing through the absorbing liquid reflux pipe 43 toward . As a result, the absorbent flowing through the absorbent supply pipe 41 from the absorption tower 3 toward the regeneration tower 5 serves as a source of cold heat, and the absorbent flowing through the absorbent reflux pipe 43 from the regeneration tower 5 toward the absorption tower 3 becomes the second 2 is cooled by heat exchanger 72 .

In the carbon dioxide recovery device 1B of the second embodiment, as in the carbon dioxide recovery device 1A of the first embodiment, an absorbent that can dissipate the absorbed carbon dioxide at 40 to 90 ° C. is used, and the heat with the exhaust gas is used. By the replacement, the absorbent is heated to 40 to 90° C. by the heater 65B. Therefore, in the second embodiment, as in the first embodiment, the energy cost can be kept low by the effective utilization of waste heat.

[Third Embodiment]
FIG. 3 is a block diagram showing a schematic configuration of a carbon dioxide recovery device 1C according to a third embodiment of the invention. In the third embodiment, the same or similar parts as those in the second embodiment are denoted by the same reference numerals in the drawings, and detailed descriptions thereof are omitted. I will explain.

In the carbon dioxide recovery apparatus 1C of the third embodiment, the heater 65C has a heat transfer jacket 85 attached to the lower portion of the regeneration tower 5. As shown in FIG. An exhaust gas supply pipe 31 is connected to the heat transfer jacket 85 so that dust-removed exhaust gas sent out from the exhaust gas treatment facility 200 is introduced/derived. In the heater 65C, heat is generated between the absorbent inside the regeneration tower 5 and the exhaust gas introduced into the heat transfer jacket 85 of the regeneration tower 5 while the exhaust gas passes through the inside of the heat transfer jacket 85 and exits. It is configured to heat the absorption liquid inside the regeneration tower 5 where exchange takes place.

In the carbon dioxide recovery device 1C of the third embodiment, the structure of the heater 65C is different from that of the heater 65B in the carbon dioxide recovery device 1B of the second embodiment. has the same configuration as Therefore, according to the third embodiment, it is possible to obtain the same effects as those of the second embodiment.

[Fourth embodiment]
FIG. 4 is a block diagram showing a schematic configuration of a carbon dioxide recovery device 1D according to the fourth embodiment of the invention. In the fourth embodiment, parts identical or similar to those in the above embodiments are denoted by the same reference numerals, and descriptions of parts overlapping with the above embodiments will be omitted.

As shown in FIG. 4, the carbon dioxide recovery apparatus 1D of the fourth embodiment includes a single-tower treatment tower 100 containing an absorbent. In the treatment tower 100, the absorption liquid and the exhaust gas are brought into contact with each other inside the treatment tower 100, and carbon dioxide is recovered by utilizing absorption/dissipation of carbon dioxide with respect to the absorption liquid inside the treatment tower 100. configured to take place.

<Treatment tower>
The treatment tower 100 is not particularly limited as long as it has a structure in which the absorption/desorption of carbon dioxide with respect to the absorption liquid can be batch-processed in a single tower without circulating the absorption liquid. can be used. In the treatment tower 100, a gas inlet 101 is provided at the bottom and a gas outlet 103 is provided at the top. An absorbent discharge port 105 is provided at the bottom, and an absorbent inlet 107 is provided at a position opposed to the gas inlet 101 at the bottom.

The gas inlet 101 of the treatment tower 100 and the exhaust gas treatment equipment 200 are connected by an exhaust gas supply pipe 31 . A gas discharge pipe 35 is connected to the gas discharge port 103 of the treatment tower 100 .

In the carbon dioxide capture device 1D of the fourth embodiment, the heater 65D has a reboiler 80 attached to the regeneration tower 5. As shown in FIG. An absorbent withdrawal pipe 81 and an absorbent return pipe 83 are connected to the reboiler 80 . The absorbent drain pipe 81 is arranged to connect the absorbent outlet 105 and the reboiler 80 . The absorbent return pipe 83 is arranged to connect the reboiler 80 and the absorbent inlet 107 . Further, the reboiler 80 is connected so that dust-removed flue gas sent out from the flue gas treatment facility 200 is introduced and discharged through the flue gas passage switching means 110 . In the heater 65D, heat exchange is performed between the absorbing liquid introduced into the reboiler 80 through the absorbing liquid discharge pipe 81 and the exhaust gas introduced into the reboiler 80 through the exhaust gas supply pipe 31, thereby reducing the exhaust gas. The absorbing liquid that has absorbed heat is returned to the inside of the processing tower 100 through the absorbing liquid return pipe 83 , thereby heating the absorbing liquid inside the processing tower 100 .

Although the detailed explanation by illustration is omitted, the exhaust gas passage switching means 110 shown in FIG. of exhaust gas is switched between a state of supplying it to the treatment tower 100 and a state of introducing/extracting it to the reboiler 80 .

In the carbon dioxide recovery apparatus 1D configured as described above, the absorption process and the recovery process are alternately performed in the single-tower treatment tower 100 .

<Absorption process>
The absorption process is performed in a state in which the exhaust gas flow path switching means 110 is switched to supply the exhaust gas sent from the exhaust gas treatment facility 200 to the treatment tower 100 . The dust-removed exhaust gas sent out from the exhaust gas treatment equipment 200 is pretreated in the pretreatment equipment 45 and sent into the absorption tower 3 through the exhaust gas supply pipe 31 . The flue gas sent into the absorption tower 3 comes into gas-liquid contact with the absorption liquid. Thereby, the carbon dioxide contained in the exhaust gas is absorbed by the absorbent. On the other hand, the exhaust gas from which carbon dioxide has been removed is discharged to the outside of the processing tower 100 through the gas discharge pipe 35 by the operation of the pump 55 .

<Regeneration step (decompression step, heating step)>
The absorption process is performed in a state in which the flue gas channel switching means 110 is switched so that the flue gas sent out from the flue gas treatment facility 200 is introduced to and discharged from the reboiler 80 . The inside of the processing tower 100 is decompressed by a pump 55 functioning as decompression means (decompression step). The absorbent inside the treatment tower 100 is heated to 40 to 90° C. by the heater 65D. Thus, in the treatment tower 100, the synergistic effect of the heating of the absorbent by the heater 65D and the pressure reduction of the absorbent by the decompression means (pump 55) efficiently diffuses carbon dioxide from the absorbent. In this way, the recovery efficiency of carbon dioxide can be further improved, and the absorbent can be regenerated into a state in which carbon dioxide can be sufficiently absorbed.

According to the carbon dioxide recovery device 1D of the fourth embodiment, carbon dioxide can be recovered with a simpler configuration than the carbon dioxide recovery devices 1A to 1C by batch processing using the single tower type treatment tower 100. .

[Fifth embodiment]
FIG. 5 is a block diagram showing a schematic configuration of a carbon dioxide recovery device 1E according to a fifth embodiment of the invention. In the fifth embodiment, the same or similar parts as those in the fourth embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. I will explain.

In the carbon dioxide recovery device 1E of the fifth embodiment, the heater 65E has a heat transfer jacket 85 attached to the lower portion of the treatment tower 100. As shown in FIG. The exhaust gas flow path switching means 110 is configured to switch between a state of supplying the dust-removed exhaust gas sent out from the exhaust gas treatment facility 200 to the processing tower 100 and a state of introducing/extracting the exhaust gas to/from the heat transfer jacket 85. there is

In the carbon dioxide recovery device 1E of the fifth embodiment, the structure of the heater 65E is different from that of the heater 65D in the carbon dioxide recovery device 1D of the fourth embodiment. has the same configuration as Therefore, according to the fifth embodiment, it is possible to obtain the same effects as those of the fourth embodiment.

[Sixth embodiment]
FIG. 6 is a block diagram showing a schematic configuration of a carbon dioxide recovery device 1F according to the sixth embodiment of the present invention. In the sixth embodiment, the same or similar parts as those in the first embodiment are denoted by the same reference numerals in the drawings, and detailed description thereof is omitted. I will explain.

As shown in FIG. 1, in the carbon dioxide recovery apparatus 1A of the first embodiment, the temperature riser 60 includes two heat exchangers, a first heat exchanger 71 and a second heat exchanger 72. A heat medium (for example, air, water, etc.) flows between the heat exchanger 71 and the second heat exchanger 72, whereby the absorbent flowing through the absorbent supply pipe 41 and the absorbent reflux pipe 43 are Heat is exchanged with the absorbent, and the temperature of the absorbent flowing through the absorbent supply pipe 41 is raised. On the other hand, as shown in FIG. 6, in the carbon dioxide recovery apparatus 1F of the sixth embodiment, the temperature riser 60 allows heat exchange between the absorbent supply pipe 41 and the absorbent reflux pipe 43. A single heat exchanger 70 is provided between the liquid supply pipe 41 and the absorbent reflux pipe 43 . In this heat exchanger 70 , heat is directly exchanged between the absorbent flowing through the absorbent supply pipe 41 and the absorbent flowing through the absorbent reflux pipe 43 . is configured to be heated. With such a carbon dioxide recovery device 1F of the sixth embodiment as well, the same effects as those of the carbon dioxide recovery device 1A of the first embodiment can be obtained.

[Seventh Embodiment]
FIG. 7 is a block diagram showing a schematic configuration of a carbon dioxide recovery device 1G according to the seventh embodiment of the invention. In the seventh embodiment, the same or similar parts as those in the sixth embodiment are denoted by the same reference numerals in the drawings, and detailed descriptions thereof are omitted. I will explain.

As shown in FIG. 6, in the carbon dioxide recovery device 1F of the sixth embodiment, the heater 65A includes two heat exchangers, a third heat exchanger 73 and a fourth heat exchanger 74. A heat medium (e.g., air, water, etc.) flows between the exchanger 73 and the fourth heat exchanger 74, whereby the absorbent flowing through the absorbent supply pipe 41 and the exhaust gas flowing through the exhaust gas supply pipe 31 are generated. heat exchange is performed between them, and the absorbing liquid flowing through the absorbing liquid supply pipe 41 after being heated by the temperature raising device 60 (heat exchanger 70) is heated. On the other hand, as shown in FIG. 7, in the carbon dioxide recovery apparatus 1G of the seventh embodiment, the heater 65A supplies the absorbent so as to allow heat exchange between the absorbent supply pipe 41 and the exhaust gas supply pipe 31. It has a single heat exchanger 75 interposed between the pipe 41 and the exhaust gas supply pipe 31 . In this heat exchanger 75, heat is directly exchanged between the absorbent flowing through the absorbent supply pipe 41 and the exhaust gas flowing through the exhaust gas supply pipe 31. It is configured to heat the absorbing liquid after being heated by 60 (heat exchanger 70). With such a carbon dioxide recovery device 1G of the seventh embodiment as well, the same effects as those of the carbon dioxide recovery device 1F of the sixth embodiment can be obtained.

As described above, the carbon dioxide recovery apparatus and the carbon dioxide recovery method of the present invention have been described based on a plurality of embodiments, but the present invention is not limited to the configurations described in the above embodiments. The configuration can be changed as appropriate without departing from the gist of the invention, such as by combining the described configurations as appropriate.

In each of the above-described embodiments, there is also a mode in which the pump 55 functioning as pressure reducing means of the present invention is omitted.

In the first embodiment, an example is shown in which the outer surface temperature of the heat transfer tubes in the fourth heat exchanger 74 is set to be higher than the dew point of the exhaust gas. There is also a mode in which heat exchange is performed until the temperature reaches the following. In this case, it is preferable to use a heat transfer tube made of a corrosion-resistant material. By recovering heat to a temperature below the dew point using a corrosion-resistant material, it is possible to greatly reduce the amount of heat transfer medium (water vapor, etc.) used in the carbon dioxide recovery apparatus 1A. Furthermore, by performing heat recovery to a temperature lower than the condensation temperature of moisture in the exhaust gas, the thermal energy corresponding to the latent heat of water can also be recovered, resulting in a greater effect. Further, when sufficient heat is not recovered from the exhaust gas introduced from the exhaust gas treatment equipment 200 to the pretreatment equipment 45, a large amount of cooling water is required to cool the exhaust gas by wet treatment in the pretreatment equipment 45. By recovering heat to a temperature below the dew point, it is possible to reduce the load of the wet treatment performed in the pretreatment equipment 45 .

The carbon dioxide recovery apparatus and the carbon dioxide recovery method of the present invention can be used, for example, in thermal power plants, ironworks, oil refineries, etc., where carbon dioxide contained in exhaust gas generated by combustion of fossil fuels, hydrogen production facilities, off-gas carbon dioxide contained in the exhaust gas generated by the combustion of waste in general waste incineration facilities It can be used in applications for separating and recovering carbon and the like.

1A to 1G carbon dioxide recovery device 3 absorption tower 5 regeneration tower 10 treatment tower 55 decompression means 65A to 65E heater 100 treatment tower

Claims (4)

A carbon dioxide recovery device that absorbs carbon dioxide contained in a carbon dioxide-containing gas into an absorption liquid and heats the absorption liquid that has absorbed the carbon dioxide to diffuse and recover the carbon dioxide,
a treatment tower containing the absorbing liquid;
a heater that heats the absorbing liquid to 40 to 90° C. where the carbon dioxide can be diffused by heat exchange with the exhaust gas that has been subjected to dust removal;
with
The treatment tower includes an absorption tower that absorbs the carbon dioxide into the absorption liquid, and a regeneration tower that dissipates the carbon dioxide from the absorption liquid that has absorbed the carbon dioxide,
The heater comprises a heat transfer jacket attached to the bottom of the regeneration tower,
the absorption tower and the regeneration tower are connected so that the absorbent is circulated between the absorption tower and the regeneration tower;
A carbon dioxide recovery device in which the dust-removed exhaust gas is introduced into the heat transfer jacket. 2. The carbon dioxide recovery apparatus according to claim 1, further comprising depressurizing means for depressurizing the inside of the regeneration tower. The heater includes a heat transfer tube in which the exhaust gas is in contact with the outer surface and a heat medium is flowed inside,
2. The carbon dioxide recovery system according to claim 1, wherein the outer surface temperature of said heat transfer tube is set to be higher than the dew point of said exhaust gas. The heater includes a heat transfer tube in which the exhaust gas is in contact with the outer surface and a heat medium is flowed inside,
The heat transfer tubes are made of a corrosion-resistant material,
The carbon dioxide recovery device according to claim 1, wherein the outer surface temperature of the heat transfer tube is set to be equal to or lower than the dew point of the exhaust gas.

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