JP6983681B2 - How to operate the carbon dioxide recovery system and the carbon dioxide recovery system - Google Patents

Description

Embodiments of the present invention relate to a carbon dioxide capture system and a method of operating the carbon dioxide capture system.

In recent years, it has been pointed out that the greenhouse effect of carbon dioxide contained in the combustion exhaust gas generated when burning fossil fuels is one of the causes of global warming.

Under such circumstances, in thermal power plants that use a large amount of fossil fuels, carbon dioxide to prevent carbon dioxide contained in the combustion exhaust gas generated by burning fossil fuels from being released into the atmosphere. Carbon recovery systems are being studied. In the carbon dioxide recovery system, the combustion exhaust gas is brought into contact with the amine-based absorbing liquid, and carbon dioxide is separated and recovered from the combustion exhaust gas.

More specifically, in the carbon dioxide recovery system, an absorption tower that absorbs carbon dioxide contained in combustion exhaust gas into an amine-based absorption liquid and an absorption liquid (rich liquid) that absorbs carbon dioxide are supplied from the absorption tower. It is equipped with a regeneration tower that heats the supplied rich liquid to release carbon dioxide from the rich liquid and regenerates the absorbed liquid. A reboiler that supplies a heat source is connected to the regeneration tower, and the rich liquid is heated in the regeneration tower. The absorption liquid (lean liquid) regenerated in the regeneration tower is supplied to the absorption tower, and the absorption liquid is configured to circulate in this system.

However, in such a carbon dioxide recovery system, when the combustion exhaust gas (decarboxylated combustion exhaust gas) obtained by absorbing carbon dioxide in an amine-based absorption liquid in the absorption tower is released from the absorption tower to the atmosphere, it is said that amine is accompanied. There was a challenge. That is, since a large amount of combustion exhaust gas is released in a thermal power plant or the like, there is a possibility that a large amount of amino group-containing compound (amine) is released along with the decarboxylated combustion exhaust gas. Therefore, when using a carbon dioxide recovery system in a thermal power plant, it is desired to effectively reduce the amine released into the atmosphere accompanying the decarboxylated combustion exhaust gas in the absorption tower. In order to deal with this, a demister may be provided in the absorption tower to recover the mist-like amine among the amines accompanying the decarboxylated combustion exhaust gas.

Japanese Unexamined Patent Publication No. 2004-323339

The present invention has been made in consideration of such points, and provides a carbon dioxide capture system and a method for operating a carbon dioxide capture system capable of effectively reducing the amount of amine released into the atmosphere. The purpose is.

In the carbon dioxide recovery system according to the embodiment, the carbon dioxide recovery unit that absorbs the carbon dioxide contained in the combustion exhaust gas into the absorption liquid containing amine and the combustion exhaust gas discharged from the carbon dioxide recovery unit are used in the second cleaning liquid. The second cleaning unit that cleans and recovers the amine that accompanies the combustion exhaust gas, and the third cleaning unit that cleans the combustion exhaust gas discharged from the second cleaning unit with the third cleaning liquid and recovers the amine that accompanies the combustion exhaust gas. It has a department. A second cleaning unit outlet demister is provided between the second cleaning unit and the third cleaning unit to capture the mist accompanying the combustion exhaust gas discharged from the second cleaning unit. A third cleaning unit outlet demister is provided to capture the mist accompanying the combustion exhaust gas discharged from the third cleaning unit. The third cleaning unit outlet demister is formed more sparsely than the second cleaning unit outlet demister.

The operation method of the carbon dioxide recovery system according to the embodiment is a step of absorbing carbon dioxide contained in the combustion exhaust gas into an absorption liquid containing an amine in the carbon dioxide recovery section, and combustion discharged from the combustion recovery section. The step of cleaning the exhaust gas with the second cleaning liquid in the second cleaning unit to recover the amine accompanying the combustion exhaust gas, and the mist accompanying the combustion exhaust gas discharged from the second cleaning unit are removed from the outlet of the second cleaning unit. A step of capturing with a demister, a step of cleaning the combustion exhaust gas discharged from the outlet demister of the second cleaning section with a third cleaning solution in the third cleaning section, and a step of recovering the amine accompanying the combustion exhaust gas, and a third cleaning. It is provided with a step of capturing the mist accompanying the combustion exhaust gas discharged from the section with the third cleaning section outlet demister. The third cleaning unit outlet demister is formed more sparsely than the second cleaning unit outlet demister.

According to the present invention, the amount of amine released into the atmosphere can be effectively reduced.

FIG. 1 is a diagram showing an overall configuration of a carbon dioxide capture system according to the first embodiment of the present invention. FIG. 2 is a graph showing the relationship between the flow rate of the cleaning liquid and the recovery efficiency of the mist-like amine in the carbon dioxide recovery system shown in FIG. FIG. 3 is a diagram showing the overall configuration of the carbon dioxide capture system according to the second embodiment of the present invention. FIG. 4 is a diagram showing the overall configuration of the carbon dioxide capture system according to the third embodiment of the present invention. FIG. 5 is a diagram showing the overall configuration of the carbon dioxide capture system according to the fourth embodiment of the present invention. FIG. 6 is a diagram showing the overall configuration of the carbon dioxide capture system according to the fifth embodiment of the present invention. FIG. 7 is a diagram showing the overall configuration of the carbon dioxide capture system according to the sixth embodiment of the present invention. FIG. 8 is a graph showing the transition of the particle size of the mist-like amine in the absorption column in the carbon dioxide capture system shown in FIG. 7. FIG. 9 is a diagram showing a modified example of the carbon dioxide capture system shown in FIG. 7.

Hereinafter, the carbon dioxide recovery system and the operation method of the carbon dioxide recovery system according to the embodiment of the present invention will be described with reference to the drawings.

(First Embodiment)
First, the carbon dioxide recovery system and the operation method of the carbon dioxide recovery system according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the carbon dioxide recovery system 1 absorbs carbon dioxide contained in combustion exhaust gas 2 into an absorption tower 20 containing an amine, and carbon dioxide supplied from the absorption tower 20. It is provided with a regeneration tower 30 that regenerates the absorbed liquid by releasing carbon dioxide from the absorbed liquid. The combustion exhaust gas 2 in which carbon dioxide is absorbed by the absorption liquid in the absorption tower 20 is discharged from the absorption tower 20 as the decarboxylated combustion exhaust gas 3 (described later). Further, carbon dioxide is discharged from the regeneration tower 30 together with steam as carbon dioxide-containing gas 8 (carbon dioxide-containing steam). The combustion exhaust gas 2 supplied to the absorption tower 20 is not particularly limited, but may be, for example, combustion exhaust gas from a boiler (not shown) of a thermal power plant, process exhaust gas, or the like, and is necessary. Accordingly, it may be supplied to the absorption tower 20 after the cooling treatment.

The absorption liquid circulates between the absorption tower 20 and the regeneration tower 30, absorbs carbon dioxide in the absorption tower 20 to become the rich liquid 4, and releases carbon dioxide in the regeneration tower 30 to become the lean liquid 5. The absorption liquid is not particularly limited, but for example, monoethanolamine, alcoholic hydroxyl group-containing primary amines such as 2-amino-2-methyl-1-propanol, diethanolamine, and 2-methylaminoethanol. Alcoholic hydroxyl group-containing secondary amines such as triethanolamine, alcoholic hydroxyl group-containing tertiary amines such as N-methyldiethanolamine, polyethylene polyamines such as ethylenediamine, triethylenediamine, diethylenetriamine, piperazins, piperidines, etc. Cyclic amines such as pyrrolidines, polyamines such as xylylene diamine, amino acids such as methylaminocarboxylic acid and the like, and mixtures thereof can be used. These amine compounds are usually used as an aqueous solution of 10 to 70% by weight. Further, a carbon dioxide absorption promoter or a corrosion inhibitor, and methanol, polyethylene glycol, sulfolane and the like can be added as other media to the absorption liquid.

The absorption tower 20 includes a carbon dioxide recovery unit 20a (packed layer or shelf stage, hereinafter referred to as a packed layer, etc.), a liquid disperser 20b provided above the carbon dioxide recovery unit 20a, a carbon dioxide recovery unit 20a, and the carbon dioxide recovery unit 20a. It has an absorption tower container 20c for accommodating the liquid disperser 20b.

The carbon dioxide recovery unit 20a is configured as a countercurrent gas-liquid contact device. That is, the carbon dioxide recovery unit 20a is composed of a packed layer or the like as an example, and the lean liquid 5 supplied from the regeneration tower 30 to the surface of the internal structure for increasing the gas-liquid contact area of the filled filling or particles. Is brought into gas-liquid contact with carbon dioxide contained in the combustion exhaust gas 2 while flowing down, and this carbon dioxide is absorbed by the lean liquid 5. In other words, carbon dioxide is recovered (or removed) from the combustion exhaust gas 2. The liquid disperser 20b disperses and drops the lean liquid 5 toward the carbon dioxide recovery unit 20a, and supplies the lean liquid 5 to the surface of the carbon dioxide recovery unit 20a. The pressure of the lean liquid 5 supplied to the liquid disperser 20b is not so high with respect to the pressure in the absorption tower 20, and the liquid disperser 20b is not substantially compulsory but mainly by the action of gravity. The lean liquid 5 is dropped onto the carbon dioxide recovery unit 20a. In the absorption tower container 20c, the carbon dioxide recovery unit 20a and the liquid disperser 20b, as well as the first cleaning unit 21, the second cleaning unit 22, the third cleaning unit 23, and the demisters 81, 82, 83, 84, which will be described later, are contained in the absorption tower container 20c. It is contained. The absorption tower container 20c receives the combustion exhaust gas 2 from the lower part of the absorption tower container 20c, and discharges the combustion exhaust gas 2 from the top of the absorption tower container 20c as the decarbonized combustion exhaust gas 3 described later.

At the lower part of the absorption tower 20, the combustion exhaust gas 2 containing carbon dioxide discharged from the outside of the carbon dioxide recovery system 1 such as the boiler described above is supplied by the blower B. The supplied combustion exhaust gas 2 rises in the absorption tower 20 toward the carbon dioxide recovery unit 20a. On the other hand, the lean liquid 5 from the regeneration tower 30 is supplied to the liquid disperser 20b and falls, is supplied to the carbon dioxide recovery unit 20a, and flows down the surface thereof. In the carbon dioxide recovery unit 20a, the combustion exhaust gas 2 and the lean liquid 5 come into gas-liquid contact, and the carbon dioxide contained in the combustion exhaust gas 2 is absorbed by the lean liquid 5 to generate the rich liquid 4.

The generated rich liquid 4 is once stored in the lower part of the absorption tower container 20c and discharged from the lower part. In the combustion exhaust gas 2 in contact with the lean liquid 5, carbon dioxide is recovered, and the carbon dioxide recovery unit 20a further rises in the absorption tower 20 as the decarboxylated combustion exhaust gas 3.

A heat exchanger 31 is provided between the absorption tower 20 and the regeneration tower 30. A rich liquid pump 32 is provided between the absorption tower 20 and the heat exchanger 31, and the rich liquid 4 discharged from the absorption tower 20 is regenerated by the rich liquid pump 32 via the heat exchanger 31. It is supplied to the tower 30. The heat exchanger 31 causes the rich liquid 4 supplied from the absorption tower 20 to the regeneration tower 30 to exchange heat with the lean liquid 5 supplied from the regeneration tower 30 to the absorption tower 20. As a result, the lean liquid 5 serves as a heat source, and the rich liquid 4 is heated to a desired temperature. In other words, the rich liquid 4 serves as a cooling heat source, and the lean liquid 5 is cooled to a desired temperature.

The regeneration tower 30 includes an amine regeneration unit 30a (filled layer or the like), a liquid disperser 30b provided above the amine regeneration unit 30a, a regeneration tower container 30c containing the amine regeneration unit 30a and the liquid disperser 30b, and the like. have. Of these, the amine regeneration unit 30a is configured as a countercurrent gas-liquid contact device. That is, the amine regeneration unit 30a is composed of a packed bed or the like as an example, and the rich liquid 4 supplied from the absorption tower 20 is applied to the surface of the internal structure for increasing the gas-liquid contact area of the packed filler or particles. While flowing down, it is brought into gas-liquid contact with the steam 7 described later, and carbon dioxide is released from the rich liquid 4. The pressure of the rich liquid 4 supplied to the liquid disperser 30b is not so high with respect to the pressure in the regeneration tower 30, and the liquid disperser 30b disperses the rich liquid 4 toward the amine regeneration unit 30a. It is dropped to supply the rich liquid 4 to the surface of the amine regeneration unit 30a. Since the pressure of the rich liquid 4 supplied to the liquid disperser 30b is not high, the liquid disperser 30b drops the rich liquid 4 onto the amine regeneration unit 30a mainly by the action of gravity rather than being substantially compulsory. The regeneration tower container 30c contains the amine regeneration unit 30a and the liquid disperser 30b, as well as the regeneration tower cleaning unit 37, which will be described later, and the demisters 86 and 87, respectively. The regeneration tower container 30c is adapted to discharge the carbon dioxide-containing gas 8 released from the rich liquid 4 from the top of the regeneration tower container 30c.

A reboiler 33 is connected to the regeneration tower 30. The reboiler 33 heats the lean liquid 5 supplied from the regeneration tower 30 by the heating medium 6 to generate steam 7, and supplies the generated steam 7 to the regeneration tower 30. More specifically, the reboiler 33 is supplied with a part of the lean liquid 5 discharged from the lower part of the regeneration tower 30, and has a high temperature as a heating medium 6 from the outside such as a turbine (not shown). Steam is supplied. The lean liquid 5 supplied to the reboiler 33 is heated by exchanging heat with the heating medium 6, and steam 7 is generated from the lean liquid 5. The generated steam 7 is supplied to the lower part of the regeneration tower 30 and heats the lean liquid 5 in the regeneration tower 30. The heating medium 6 is not limited to the high-temperature steam from the turbine.

Steam 7 is supplied from the reboiler 33 to the lower part of the regeneration tower 30, and rises in the regeneration tower 30 toward the amine regeneration section 30a. On the other hand, the rich liquid 4 from the absorption tower 20 is supplied to the liquid disperser 30b and drops, is supplied to the amine regeneration unit 30a, and flows down the surface thereof. In the amine regeneration unit 30a, the rich liquid 4 and the steam 7 are in gas-liquid contact, and carbon dioxide gas is released from the rich liquid 4 to generate a lean liquid 5. In this way, the absorption liquid is regenerated in the regeneration tower 30.

The generated lean liquid 5 is discharged from the lower part of the regeneration tower 30, and the vapor 7 in gas-liquid contact with the rich liquid 4 contains carbon dioxide and is discharged from the top of the regeneration tower 30 as carbon dioxide-containing gas 8. To. The carbon dioxide-containing gas 8 emitted also contains steam.

A lean liquid pump 34 is provided between the regeneration tower 30 and the heat exchanger 31. The lean liquid 5 discharged from the regeneration tower 30 is supplied to the absorption tower 20 by the lean liquid pump 34 via the heat exchanger 31 described above. As described above, the heat exchanger 31 cools the lean liquid 5 supplied from the regeneration tower 30 to the absorption tower 20 by heat exchange with the rich liquid 4 supplied from the absorption tower 20 to the regeneration tower 30. Further, a lean liquid cooler 35 is provided between the heat exchanger 31 and the absorption tower 20. The lean liquid cooler 35 is supplied with a cooling medium such as cooling water (for example, cooling water of a cleaning tower or seawater) from the outside, and further cools the lean liquid 5 cooled in the heat exchanger 31 to a desired temperature. do.

The lean liquid 5 cooled in the lean liquid cooler 35 is supplied to the liquid disperser 20b of the absorption tower 20 and falls, is supplied to the carbon dioxide recovery unit 20a, and flows down the surface thereof. In the carbon dioxide recovery unit 20a, the lean liquid 5 comes into gas-liquid contact with the combustion exhaust gas 2, and the carbon dioxide contained in the combustion exhaust gas 2 is absorbed by the lean liquid 5 to become the rich liquid 4. In this way, in the carbon dioxide recovery system 1, the absorption liquid is circulated while repeating the state of becoming the lean liquid 5 and the state of becoming the rich liquid 4.

The carbon dioxide recovery system 1 shown in FIG. 1 includes a gas cooler 40 that cools the carbon dioxide-containing gas 8 discharged from the top of the regeneration tower 30 and condenses steam to generate condensed water 9, and gas cooling. Further, a gas-liquid separator 41 for separating the condensed water 9 generated by the vessel 40 from the carbon dioxide-containing gas 8 is provided. In this way, the water content in the carbon dioxide-containing gas 8 is reduced, and the carbon dioxide-containing gas 8 is discharged as the carbon dioxide gas 10 from the gas-liquid separator 41, and is supplied to and stored in equipment (not shown). To. On the other hand, the condensed water 9 separated in the gas-liquid separator 41 is supplied to the regeneration tower 30 by the condensed water pump 42 and mixed with the absorbing liquid. The gas cooler 40 is supplied with a cooling medium for cooling the carbon dioxide-containing gas 8 (for example, cooling water of a cleaning tower or seawater) from the outside.

By the way, a first cleaning unit 21, a second cleaning unit 22, and a third cleaning unit 23 are provided in the absorption tower 20, of which the first cleaning unit 21 is a carbon dioxide recovery unit 20a. The decarbonated combustion exhaust gas 3 discharged from the above is washed with the first cleaning liquid 11 (first cleaning water) to recover the amine which is an absorption liquid component accompanying the decarbonized combustion exhaust gas 3. The second cleaning unit 22 cleans the decarboxylated combustion exhaust gas 3 discharged from the first cleaning unit 21 with the second cleaning liquid 12 (second cleaning water), and recovers the amine accompanying the decarboxylated combustion exhaust gas 3. .. The third cleaning unit 23 cleans the decarboxylated combustion exhaust gas 3 discharged from the second cleaning unit 22 with the third cleaning liquid 13 (third cleaning water), and recovers the amine accompanying the decarboxylated combustion exhaust gas 3. .. Of these, the first cleaning unit 21 is provided above the liquid disperser 20b, the second cleaning unit 22 is provided above the first cleaning unit 21, and the third cleaning unit 23 is the second cleaning unit 22. It is provided above.

The first cleaning section 21 includes a first recovery space 21d, a first injector 21e provided above the first recovery space 21d, and a first receiving section 21c provided below the first recovery space 21d. have,

In the first recovery space 21d, the first cleaning liquid 11 supplied at the first pressure and ejected from the first injector 21e may freely fall in a mist state (that is, come into contact with the surface of a structure or the like in the space). A space that comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3 that rises through the first receiving portion 21c while falling (falling without being present), and is an amine (mainly mist-like amine, absorbed) that accompanies the decarboxylated combustion exhaust gas 3. It is a space to collect liquid mist). The first recovery space 21d is formed from the first injector 21e to the first receiving portion 21c.

In the present embodiment, between the first injector 21e and the first receiving portion 21c, a packed layer, a shelf, or the like for allowing the first cleaning liquid 11 to come into contact with the decarboxylated combustion exhaust gas 3 while flowing down the surface is provided. No structure is provided. That is, no member such as a structure for the first cleaning liquid 11 to flow down the surface is provided between the first injector 21e and the first receiving portion 21c, and the first injector 21e to the first. Since the first recovery space 21d is formed over the receiving portion 21c, the first recovery space 21d is configured so that the first cleaning liquid 11 freely falls and comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3. The mist of the first cleaning liquid 11 injected from the first injector 21e falls in the first recovery space 21d where the decarboxylated combustion exhaust gas 3 rises and reaches the first receiving portion 21c directly. .. That is, the first cleaning liquid 11 that has passed through the first recovery space 21d is configured to be directly received by the first receiving portion 21c. During the fall, the first cleaning liquid 11 comes into contact with the decarboxylated combustion exhaust gas 3, and the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 collides with the first cleaning liquid 11 and is recovered.

The first injector 21e injects the first cleaning liquid 11 supplied at the first pressure toward the first recovery space 21d and drops it. The first injector 21e includes a plurality of spray nozzle holes (not shown), and the pressure is increased by the first circulation pump 51 described later to inject the first cleaning liquid 11 supplied at the first pressure from the spray nozzle holes. (Spray). As a result, the first cleaning liquid 11 becomes a mist and is jetted at high speed from the first injector 21e, and freely falls while evenly distributed in the first recovery space 21d. That is, the first injector 21e gives the first cleaning liquid 11 the initial velocity component in the vertical direction as the velocity component in the vertical direction, and gives the first recovery space 21d a velocity component in the vertical direction to forcibly fall freely. Let (spray).

The first receiving unit 21c is configured to receive and store the first cleaning liquid 11 that has fallen in the first recovery space 21d, and to allow the decarboxylated combustion exhaust gas 3 discharged from the carbon dioxide recovery unit 20a and rising to pass through. .. That is, the first receiving portion 21c has an opening provided between the receiving portion main body that receives and stores the first cleaning liquid 11 and the receiving portion main body through which the decarboxylated combustion exhaust gas 3 passes, and the opening from above. It is composed of a cover and a cover for preventing the first cleaning liquid 11 from passing through the opening.

A first circulation line 50 for circulating the first cleaning liquid 11 is connected to the first cleaning unit 21. That is, the first circulation pump 51 is provided in the first circulation line 50 so that the first cleaning liquid 11 stored in the first receiving portion 21c is taken out and the first pressure is applied to the first injector 21e. The first cleaning liquid 11 is circulated.

The second cleaning unit 22 is provided below the second collecting unit 22a (packed bed or the like), the second cleaning liquid disperser 22b provided above the second collecting unit 22a, and the second collecting unit 22a. It has two receiving portions 22c.

The second recovery unit 22a is configured as a countercurrent gas-liquid contact device. That is, the second recovery unit 22a is composed of a packing layer or the like as an example, and decarboxylates while flowing the second cleaning liquid 12 onto the surface of the internal structure for increasing the gas-liquid contact area of the filled filling or particles. The amine (mainly gaseous amine) accompanying the decarboxylated combustion exhaust gas 3 is recovered by contacting the combustion exhaust gas 3 with gas and liquid, and the amine is removed from the decarboxylated combustion exhaust gas 3. The second cleaning liquid disperser 22b disperses and drops the second cleaning liquid 12 supplied by the second pressure toward the second recovery unit 22a, and flows down the surface of the structure inside the second recovery unit 22a. The second cleaning liquid 12 is supplied as described above. The second pressure is lower than the first pressure, which is the pressure of the first cleaning liquid 11 supplied to the first injector 21e of the first cleaning unit 21. The pressure (second pressure) of the second cleaning liquid 12 supplied to the second cleaning liquid disperser 22b is a pressure that is not so high with respect to the pressure in the absorption tower 20. The second vertical initial velocity, which is a vertical velocity component given to the second cleaning liquid 12 dispersed by the second cleaning liquid disperser 22b, is the vertical direction given to the first cleaning liquid 11 by the first injector 21e of the first cleaning unit 21. It is smaller than the first vertical initial velocity, which is the velocity component of. The second vertical initial velocity, which is substantially the vertical velocity component given to the second cleaning liquid 12, is almost 0 (zero), and the second cleaning liquid disperser 22b is non-forced by the action of gravity. 2 The cleaning liquid 12 is freely dropped onto the second recovery unit 22a. The second receiving unit 22c receives and stores the second cleaning liquid 12 that has flowed down the surface of the internal structure in the second collecting unit 22a, and is discharged from the first collecting space 21d of the first cleaning unit 21 to rise. It is configured so that the carbonic acid combustion exhaust gas 3 can pass through. The second receiving portion 22c is configured in the same manner as the first receiving portion 21c.

A second circulation line 54 for circulating the second cleaning liquid 12 is connected to the second cleaning unit 22. That is, the second circulation pump 55 is provided in the second circulation line 54, and the second cleaning liquid 12 stored in the second receiving portion 22c is taken out and supplied to the second cleaning liquid disperser 22b to be supplied to the second cleaning liquid disperser 22b. The cleaning liquid 12 is circulated.

In the present embodiment, the second circulation line 54 is provided with a second cleaning liquid cooler 56 for cooling the second cleaning liquid 12. The second cleaning liquid cooler 56 is supplied with a cooling medium (for example, cooling water of the cleaning tower or seawater) from the outside of the carbon dioxide recovery system 1 as a cooling medium for cooling the second cleaning liquid 12. In this way, the second cleaning liquid cooler 56 cools the second cleaning liquid 12 flowing through the second circulation line 54, and the temperature of the second cleaning liquid 12 is lower than the temperature of the first cleaning liquid 11. is doing. The temperature of the second cleaning liquid 12 and the temperature of the first cleaning liquid 11 may be configured to be substantially the same.

The third cleaning unit 23 includes a third collecting unit 23a (packed bed and the like), a third cleaning liquid disperser 23b provided above the third collecting unit 23a, and a third cleaning unit 23a provided below the third collecting unit 23a. It has 3 receiving portions 23c and.

The third recovery unit 23a is configured as a countercurrent gas-liquid contact device. That is, the third recovery unit 23a is composed of a filling layer or the like as an example, and decarboxylates while flowing the third cleaning liquid 13 onto the surface of the internal structure for increasing the gas-liquid contact area of the filled filling or particles. The amine (mainly gaseous amine) accompanying the decarboxylated combustion exhaust gas 3 is recovered by contacting the combustion exhaust gas 3 with gas and liquid, and the amine is removed from the decarboxylated combustion exhaust gas 3. The third cleaning liquid disperser 23b disperses and drops the third cleaning liquid 13 supplied at the third pressure toward the third recovery unit 23a, and flows down the surface of the structure inside the third recovery unit 23a. The third cleaning liquid 13 is supplied as described above. The third pressure is lower than the first pressure, which is the pressure of the first cleaning liquid 11 supplied to the first injector 21e of the first cleaning unit 21. The pressure (third pressure) of the third cleaning liquid 13 supplied to the third cleaning liquid disperser 23b is a pressure that is not so high with respect to the pressure in the absorption tower 20. The third vertical initial velocity, which is a vertical velocity component given to the third cleaning liquid 13 dispersed by the third cleaning liquid disperser 23b, is the vertical direction given to the first cleaning liquid 11 by the first injector 21e of the first cleaning unit 21. It is smaller than the first vertical initial velocity, which is the velocity component of. The third vertical initial velocity, which is substantially the vertical velocity component given to the third cleaning liquid 13, is almost 0 (zero), and the third cleaning liquid disperser 23b is not forced to be the third by the action of gravity. 3 The cleaning liquid 13 is freely dropped onto the third recovery unit 23a. The third receiving unit 23c receives and stores the third cleaning liquid 13 that has flowed down the surface of the internal structure in the third collecting unit 23a, and is discharged from the second collecting unit 22a of the second cleaning unit 22 to rise. It is configured so that the carbonic acid combustion exhaust gas 3 can pass through. The third receiving portion 23c is configured in the same manner as the first receiving portion 21c and the second receiving portion 22c. The third pressure, which is the pressure of the third cleaning liquid 13 supplied to the third cleaning liquid disperser 23b, should be equal to, for example, the second pressure, which is the pressure of the second cleaning liquid 12 supplied to the second cleaning liquid disperser 22b. Can be done. Similarly, the vertical initial velocity, which is the vertical velocity component given to the third cleaning liquid 13 dispersed by the third cleaning liquid disperser 23b, is given to the second cleaning liquid 12 dispersed by the second cleaning liquid disperser 22b. It can also be configured to be equal to the initial velocity component in the second vertical direction.

A third circulation line 57 for circulating the third cleaning liquid 13 is connected to the third cleaning unit 23. That is, the third circulation pump 58 is provided in the third circulation line 57, and the third cleaning liquid 13 stored in the third receiving portion 23c is taken out and supplied to the third cleaning liquid disperser 23b to be supplied to the third cleaning liquid disperser 23b. The cleaning liquid 13 is circulated.

In the present embodiment, the third circulation line 57 is provided with a third cleaning liquid cooler 59 for cooling the third cleaning liquid 13. The third cleaning liquid cooler 59 is supplied with a cooling medium (for example, cooling water of the cleaning tower or seawater) from the outside of the carbon dioxide recovery system 1 as a cooling medium for cooling the third cleaning liquid 13. In this way, the third cleaning liquid cooler 59 cools the third cleaning liquid 13 flowing through the third circulation line 57.

By the way, the flow rate (first flow rate) per unit area and unit time of the first cleaning liquid 11 ejected from the first injector 21e of the first cleaning unit 21 is from the second cleaning liquid disperser 22b of the second cleaning unit 22. The unit area of the second cleaning liquid 12 to be dispersed, which is larger than the flow rate per unit time (second flow rate), and the unit area of the third cleaning liquid 13 of the third cleaning liquid disperser 23b of the third cleaning unit 23. It is larger than the flow rate per unit time (third flow rate). The flow rate of the first cleaning liquid 11 injected from the first injector 21e is adjusted by the above-mentioned first circulation pump 51 (flow rate adjusting unit). Similarly, the flow rate of the second cleaning liquid 12 dispersed from the second cleaning liquid disperser 22b is adjusted by the above-mentioned second circulation pump 55, and the flow rate of the third cleaning liquid 13 dispersed from the third cleaning liquid disperser 23b is set. It is adjusted by the third circulation pump 58 described above.

The unit area shown here is the horizontal cross-sectional area where the first injector 21e injects the first cleaning liquid 11 (or the horizontal cross-sectional area of the first cleaning unit 21), and the second cleaning liquid disperser 22b is the second cleaning liquid. A horizontal cross-sectional area that disperses 12 (or a horizontal cross-sectional area of the second cleaning unit 22), and a horizontal cross-sectional area that the third cleaning liquid disperser 23b disperses the third cleaning liquid 13 (or a horizontal cross-sectional area of the second cleaning unit 22). Is the unit area for. In the present embodiment, since the horizontal cross-sectional areas of the first cleaning unit 21, the second cleaning unit 22 and the third cleaning unit 23 are substantially the same, each cleaning unit (first cleaning unit 21, second cleaning unit 22 and second cleaning unit 22) The first flow rate, the second flow rate, and the third flow rate may be set according to the flow rate per unit time without considering the difference in the horizontal cross-sectional area of the cleaning unit 23).

If generalized including the case where the horizontal cross-sectional areas of the cleaning units 21 to 23 are different, for example, the flow rate per unit area and unit time (first flow rate) of the first cleaning liquid 11 injected from the first injector 21e can be obtained. , 300 L / min / m ² or more, the unit area of the second cleaning liquid 12 distributed from the second cleaning liquid disperser 22b, the flow rate per unit time (second flow rate), and the second flow rate dispersed from the third cleaning liquid disperser 23b. 3 The flow rate per unit area / unit time (third flow rate) of the cleaning liquid 13 may be 50 L / min / m ^{2 to} 150 L / min / m ² (normal flow rate range shown in FIG. 2).

The first pressure (pressure in the first injector 21e) of the first cleaning liquid 11 supplied to the first injector 21e of the first cleaning unit 21 is supplied to the second cleaning liquid disperser 22b of the second cleaning unit 22. The pressure is higher than the second pressure (pressure in the second cleaning liquid disperser 22b) of the second cleaning liquid 12, and the third cleaning liquid 13 supplied to the third cleaning liquid disperser 23b of the third cleaning unit 23. It is higher than the 3 pressure (pressure in the 3rd cleaning liquid disperser 23b). The first pressure of the first cleaning liquid 11 supplied to the first injector 21e is adjusted by the above-mentioned first circulation pump 51 (pressure adjusting unit). Similarly, the second pressure of the second cleaning liquid 12 supplied to the second cleaning liquid disperser 22b is adjusted by the above-mentioned second circulation pump 55, and the third cleaning liquid 13 supplied to the third cleaning liquid disperser 23b. The three pressures are adjusted by the third circulation pump 58 described above. For example, the first pressure of the first cleaning liquid 11 supplied to the first injector 21e may be 0.1 MPa to 0.8 MPa. The second pressure of the second cleaning liquid 12 supplied to the second cleaning liquid disperser 22b and the third pressure of the third cleaning liquid 13 supplied to the third cleaning liquid disperser 23b may be 0.1 MPa or less. For example, the discharge pressures of the first circulation pump 51, the second circulation pump 55, and the third circulation pump 58 are lifted to the first injector 21e, the second cleaning liquid disperser 22b, and the third cleaning liquid disperser 23b, respectively (water head). ), The first pressure, the second pressure, and the third pressure can be appropriately set as described above.

The particle size of the first cleaning liquid 11 ejected from the first injector 21e of the first cleaning unit 21 should be small. This is because the number of mists can be increased by reducing the particle size of the mist of the first cleaning liquid 11 when considered at the same flow rate. In this case, the probability of physical collision with the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 can be increased. For example, the central particle size of the first cleaning liquid 11 may be 100 μm to 1000 μm, preferably 200 μm to 800 μm. The spray nozzle hole of the first injector 21e described above is configured to be able to form a mist of the first cleaning liquid 11 having such a central particle size. Here, the central particle size is the average value of the particle size of the first cleaning liquid 11 ejected from the first injector 21e. The central particle size may be appropriately defined by a median value in addition to the average value of the particle size, or a function using the average value and the median value, as well as the variance and the standard deviation of the image.

By the way, above the carbon dioxide recovery unit 20a, a recovery unit outlet demister 81 is provided. More specifically, the recovery unit outlet demister 81 is provided between the carbon dioxide recovery unit 20a and the first cleaning unit 21 (between the liquid disperser 20b and the first receiving unit 21c). As a result, the decarboxylated combustion exhaust gas 3 discharged from the carbon dioxide recovery unit 20a passes through the recovery unit outlet demister 81 and rises. The recovery unit outlet demister 81 captures mist (mainly mist-like amine) accompanying the decarboxylated combustion exhaust gas 3 passing through.

A first cleaning unit outlet demister 82 is provided above the first cleaning unit 21. More specifically, the first cleaning unit outlet demister 82 is provided between the first cleaning unit 21 and the second cleaning unit 22 (between the first injector 21e and the second receiving unit 22c). As a result, the decarboxylated combustion exhaust gas 3 discharged from the first cleaning unit 21 passes through the first cleaning unit outlet demister 82 and rises. The first cleaning unit outlet demister 82 captures mist (mainly mist-like amine and mist of the first cleaning liquid 11) accompanying the decarboxylated combustion exhaust gas 3 passing through.

A second cleaning unit outlet demister 83 is provided above the second cleaning unit 22. More specifically, the second cleaning unit outlet demister 83 is provided between the second cleaning unit 22 and the third cleaning unit 23 (between the second cleaning liquid disperser 22b and the third receiving unit 23c). .. As a result, the decarboxylated combustion exhaust gas 3 discharged from the second cleaning unit 22 passes through the third cleaning unit outlet demister 84 and rises. The second cleaning unit outlet demister 83 captures the mist (mainly the mist-like amine and the mist of the second cleaning liquid 12) accompanying the decarboxylated combustion exhaust gas 3 passing through.

A third cleaning unit outlet demister 84 is provided above the third cleaning unit 23. More specifically, the third cleaning unit outlet demister 84 is provided above the third cleaning liquid disperser 23b of the third cleaning unit 23 (between the third cleaning liquid disperser 23b and the top of the absorption tower container 20c). There is. As a result, the decarboxylated combustion exhaust gas 3 discharged from the third cleaning unit 23 passes through the third cleaning unit outlet demister 84 and rises. The third cleaning unit outlet demister 84 captures mist (mainly mist-like amine and mist of the third cleaning liquid 13) accompanying the decarboxylated combustion exhaust gas 3.

In the present embodiment, the third cleaning unit outlet demister 84 is formed more sparsely than the second cleaning unit outlet demister 83.

The fact that demisters are sparsely or densely formed can be explained, for example, by the porosity of demisters. More specifically, the magnitude of the porosity of the demister may be made to correspond sparsely or densely with the demister. In this case, the fact that the third cleaning unit outlet demister 84 is formed more sparsely than the second cleaning unit outlet demister 83 means that the porosity of the third cleaning unit outlet demister 84 is that of the second cleaning unit outlet demister 83. It is synonymous with being larger than the porosity. As a result, the space through which the decarboxylated combustion exhaust gas 3 passes is increased in the third cleaning unit outlet demister 84, and the decarboxylated combustion exhaust gas 3 can easily pass through. Therefore, the pressure loss generated in the flow of the decarboxylated combustion exhaust gas 3 can be reduced. For example, when the second cleaning unit outlet demister 83 and the third cleaning unit outlet demister 84 are mesh-shaped demisters, the mesh of the third cleaning unit outlet demister 84 is larger than the mesh of the second cleaning unit outlet demister 83. It may be rough. Similarly, the third cleaning unit outlet demister 84 may be formed more sparsely than the first cleaning unit outlet demister 82.

The fact that the demisters are sparsely or densely formed can also be explained, for example, by the mist removal (or recovery) rate characteristics of the demisters. More specifically, when the characteristics of the demister are shown by the removal rate of mist in a predetermined particle size range (for example, 0.1 μm to 10 μm), the magnitude of the removal rate corresponds to the sparse or dense of the demister. You may let me. In this case, the fact that the third cleaning unit outlet demister 84 is formed more sparsely than the second cleaning unit outlet demister 83 means that the removal rate of mist in the predetermined particle size range in the third cleaning unit outlet demister 84 is determined. It is synonymous with being smaller than the removal rate of the second cleaning unit outlet demister 83.

Further, in the present embodiment, the recovery unit outlet demister 81 is formed more sparsely than the first cleaning unit outlet demister 82 and / or the second cleaning unit outlet demister 83, similarly to the third cleaning unit outlet demister 84. You may.

Further, as shown in FIG. 1, the regeneration tower 30 washes the carbon dioxide-containing gas 8 discharged from the amine regeneration unit 30a described above with condensed water 9 to recover the amine accompanying the carbon dioxide-containing gas 8. It has a regeneration tower cleaning unit 37 to be used. The regeneration tower cleaning unit 37 is provided above the amine regeneration unit 30a.

The regeneration tower cleaning unit 37 has a regeneration tower recovery unit 37a (filled bed or the like) and a liquid disperser 37b provided above the regeneration tower recovery unit 37a. Of these, the regeneration tower recovery unit 37a is configured as a countercurrent gas-liquid contact device. That is, the regeneration tower recovery unit 37a is composed of a filling layer or the like as an example, and contains carbon dioxide while flowing condensed water 9 down on the surface of an internal structure for increasing the gas-liquid contact area of the filled filling or particles. The amine is recovered from the carbon dioxide-containing gas 8 by gas-liquid contact with the gas 8. The liquid disperser 37b disperses and drops the condensed water 9 toward the regeneration tower recovery unit 37a, and supplies the condensed water 9 to the surface of the regeneration tower recovery unit 37a. The liquid disperser 37b drops the condensed water 9 by the action of gravity rather than compulsion.

By the way, a first regeneration tower demister 86 is provided above the amine regeneration portion 30a of the regeneration tower 30. More specifically, the first regeneration tower demister 86 is provided between the amine regeneration unit 30a and the regeneration tower cleaning unit 37 (between the liquid disperser 30b and the regeneration tower recovery unit 37a). As a result, the carbon dioxide-containing gas 8 discharged from the amine regeneration unit 30a passes through the first regeneration tower demister 86 and rises. The first regeneration tower demister 86 captures mist (mainly mist-like amine) accompanying the passing carbon dioxide-containing gas 8.

A second regeneration tower demister 87 is provided above the regeneration tower cleaning unit 37. More specifically, the second regeneration tower demister 87 is provided above the liquid disperser 37b of the regeneration tower cleaning unit 37 (between the liquid disperser 37b and the top of the regeneration tower container 30c). As a result, the carbon dioxide-containing gas 8 discharged from the regeneration tower cleaning unit 37 passes through the second regeneration tower demister 87 and rises. The second regeneration tower demister 87 captures the mist-like amine and the mist of the condensed water 9 accompanying the passing carbon dioxide-containing gas 8.

Next, the operation of the present embodiment having such a configuration, that is, the operation method of the carbon dioxide capture system will be described.

During the operation of the carbon dioxide recovery system shown in FIG. 1, in the carbon dioxide recovery unit 20a of the absorption tower 20, the lean liquid 5 supplied from the lean liquid cooler 35 is dispersed and dropped from the liquid disperser 20b to recover carbon dioxide. While flowing down the surface of the portion 20a, it comes into gas-liquid contact with the combustion exhaust gas 2. The carbon dioxide contained in the combustion exhaust gas 2 is absorbed by the lean liquid 5. The combustion exhaust gas 2 is discharged from the carbon dioxide recovery unit 20a as the decarboxylated combustion exhaust gas 3. The discharged decarboxylated combustion exhaust gas 3 rises in the absorption tower container 20c and passes through the recovery unit outlet demister 81.

The recovery unit outlet demister 81 mainly captures the mist-like amine having a large particle size among the mist-like amines accompanying the decarboxylated combustion exhaust gas 3.

That is, the recovery unit outlet demister 81 is provided directly above the liquid disperser 20b, and is a demister through which the decarboxylated combustion exhaust gas 3 discharged from the carbon dioxide recovery unit 20a first passes. Therefore, there is a possibility that the decarboxylated combustion exhaust gas 3 passing through the recovery unit outlet demister 81 is accompanied by a mist-like amine having a relatively large particle size. When the mist-like amine having a large particle size reaches the first cleaning unit 21, the amine concentration of the first cleaning liquid 11 may increase, and the cleaning capacity of the first cleaning liquid 11 may be significantly reduced. Therefore, the recovery unit outlet demister 81 is provided for the purpose of recovering a mist-like amine having a large particle size. For this reason, the recovery unit outlet demister 81 is sparsely formed as described above. In this case, it is possible to reduce the pressure loss generated in the flow of the decarboxylated combustion exhaust gas 3 passing through the recovery unit outlet demister 81.

The decarboxylated combustion exhaust gas 3 that has passed through the recovery section outlet demister 81 passes through the first receiving section 21c of the first cleaning section 21 and reaches the first recovery space 21d.

On the other hand, the first cleaning liquid 11 stored in the first receiving portion 21c is withdrawn from the first receiving portion 21c by the first circulation pump 51, passes through the first circulation line 50, and exerts a second pressure on the first injector 21e. It is supplied at a first pressure higher than the third pressure. In the present embodiment, since the first circulation line 50 is not provided with the heaters 52, 53 (see FIGS. 3 and 4) and the cooler described later, the first circulation line 50 passes through the first circulation line 50. 1 The cleaning liquid 11 is neither actively heated nor cooled.

The first cleaning liquid 11 is sprayed from the spray nozzle hole of the first injector 21e, falls in the first recovery space 21d, and reaches the first receiving portion 21c directly. During this time, the first cleaning liquid 11 comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3 while falling in a mist state, and the decarboxylated combustion exhaust gas 3 is washed with the first cleaning liquid 11. As a result, the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 is mainly recovered in the first cleaning liquid 11. The first cleaning liquid 11 that has reached the first receiving portion 21c is received and stored in the first receiving portion 21c.

Here, in the carbon dioxide capture system 1, a general problem when cleaning the decarboxylated combustion exhaust gas 3 will be described.

Generally, in the carbon dioxide recovery system 1, in order to recover the amine accompanying the decarboxylated combustion exhaust gas 3, a packed layer or a shelf for allowing the cleaning liquid to flow down may be provided on the surface. In this case, the contact area between the decarboxylated combustion exhaust gas 3 and the cleaning liquid increases, and the amine can be efficiently recovered.

The amine accompanying the decarboxylated combustion exhaust gas 3 is roughly classified into a gaseous amine and a mist amine. Of these, gaseous amines are easily recovered by washing with a washing liquid and a packed bed. On the other hand, mist-like amines are difficult to recover by washing with a washing liquid and a packed bed. The mist-like amine is easily trapped by the demister, but it becomes difficult to be trapped by the demister when the particle size of the mist is 5 μm or less.

Therefore, in the present embodiment, the recovery efficiency of the mist-like amine is improved by turning the cleaning liquid into a mist. That is, in the present embodiment, the pressure of the first cleaning liquid 11 supplied to the first injector 21e of the first cleaning unit 21 is increased, and the first cleaning liquid 11 is (1) from the spray nozzle hole of the first injector 21e. It is injected at high speed (especially immediately after injection). As a result, the mist of the first cleaning liquid 11 physically collides with the mist-like amine accompanying the decarboxylated combustion exhaust gas 3, and the mist-like amine is captured and recovered by the mist of the first cleaning liquid 11. The first cleaning liquid 11 from which the mist-like amine is recovered falls onto the first receiving portion 21c. In this way, the mist-like amine that is difficult to be captured by cleaning using the cleaning liquid and the packed bed or the like is recovered in the first cleaning liquid 11, and the decarboxylated combustion exhaust gas 3 is efficiently washed.

Further, as described above, the first cleaning liquid 11 ejected from the first injector 21e freely falls in the first recovery space 21d in which the packed layer or the like is not provided without contacting the surface of the structure or the like. .. In this case, since the mist of the first cleaning liquid 11 directly reaches the first receiving portion 21c without colliding with a member such as a structure, it is possible to prevent the mist of the first cleaning liquid 11 from being miniaturized.

That is, the first cleaning unit 21 has a recovery unit (first recovery unit 21a shown in FIG. 9 to be described later) composed of a packed bed or the like like the second cleaning unit 22 or the third cleaning unit 23. In this case, the mist of the first cleaning liquid 11 ejected from the first injector 21e at high speed collides with the packed bed or the like and is made finer. In this case, the particle size of the mist of the first cleaning liquid 11 becomes small, and it becomes easy to accompany the decarboxylated combustion exhaust gas 3. Therefore, the first cleaning liquid 11 from which the amine has been recovered is discharged to the atmosphere along with the decarboxylated combustion exhaust gas 3, which causes a problem that the cleaning efficiency is lowered.

However, in the present embodiment, the first recovery space 21d is formed below the first injector 21e, and no member such as a structure such as a packed bed is provided. Therefore, it is possible to prevent the mist of the first cleaning liquid 11 from being miniaturized, and it is possible to prevent a decrease in cleaning efficiency. For example, by setting the distance from the first injector 21e to the first receiving portion 21c to at least 1 m or more, preferably 1.5 m or more, a sufficient first recovery space 21d can be provided. In this case, when the mist of the first cleaning liquid 11 reaches the first receiving portion 21c, the speed can be reduced, and it is possible to prevent the mist from colliding with the first receiving portion 21c and becoming finer.

By the way, the injection speed and particle size of the mist of the first cleaning liquid 11 can also contribute to the improvement of the cleaning efficiency of the decarboxylated combustion exhaust gas 3. Therefore, it is preferable that the first pressure of the first cleaning liquid 11 supplied to the first injector 21e is increased to, for example, 0.1 MPa to 0.8 MPa. By setting the first pressure of the first cleaning liquid 11 to 0.1 MPa or more, the mist injection speed of the first cleaning liquid 11 can be increased. On the other hand, by setting the first pressure of the first cleaning liquid 11 to 0.8 MPa or less, it is possible to prevent the particle size of the mist of the sprayed first cleaning liquid 11 from becoming broad (having a wide particle size distribution). Cleaning performance can be stabilized. Further, the increase in the capacity (required power) of the first circulation pump 51 can be suppressed, and the increase in the operating cost can be suppressed.

The central particle size of the first cleaning liquid 11 to be sprayed is preferably 100 μm to 1000 μm, particularly preferably 200 μm to 800 μm. Here, by setting the central particle size to 100 μm or more, it is possible to prevent the flow of the decarboxylated combustion exhaust gas 3 from being accompanied by the mist of the first cleaning liquid 11 containing an amine and reducing the cleaning efficiency. In order to further prevent the mist of the first cleaning liquid 11 from being accompanied by the decarboxylated combustion exhaust gas 3, the particle size of the first cleaning liquid 11 injected from the first injector 21e may be 200 μm or more. On the other hand, by setting the central particle size to 1000 μm or less, the particle size of the mist of the first cleaning liquid 11 can be reduced, the number of mists of the first cleaning liquid 11 is increased, and the mist accompanying the decarboxylated combustion exhaust gas 3 is increased. The probability of collision with the state amine can be increased. In order to further increase the probability of collision with the mist-like amine accompanying the decarboxylated combustion exhaust gas 3, the particle size of the first cleaning liquid 11 injected from the first injector 21e may be 800 μm or less.

Further, the flow rate (first flow rate) per unit area / unit time of the first cleaning liquid 11 injected from the first injector 21e may be 300 L / min / m ² or more. Here, the flow rate (second flow rate) per unit area / unit time of the second cleaning liquid 12 dispersed from the second cleaning liquid disperser 22b of the second cleaning unit 22 is 50 L / min / m ^{2 to} 150 L / min / min. It is set to m ^2. The same applies to the unit area of the third cleaning liquid 13 and the flow rate per unit time (third flow rate). The second cleaning liquid 12 dispersed from the second cleaning liquid disperser 22b comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3 while flowing down the surface of the second recovery unit 22a composed of a packed bed or the like. Therefore, even if the flow rate per unit area and unit time of the second cleaning liquid 12 ^{is larger than 150 L / min / m 2} , the contribution to the improvement of the cleaning efficiency of the decarboxylated combustion exhaust gas 3 is limited. Further, increasing the flow rate of the second cleaning liquid 12 more than necessary increases the capacity of the second circulation pump 55 and increases the operating cost, which is not preferable. However, in the first cleaning unit 21, the first cleaning liquid 11 injected from the first injector 21e is brought into gas-liquid contact with the decarboxylated combustion exhaust gas 3 in a mist state without providing a member such as a packed bed. Thereby, increasing the flow rate per unit area and unit time of the first cleaning liquid 11 can contribute to increasing the physical collision probability with the mist-like amine accompanying the decarboxylated combustion exhaust gas 3. , The cleaning efficiency of the decarboxylated combustion exhaust gas 3 can be improved. This is shown in FIG.

FIG. 2 is a graph showing the relationship between the flow rate of the first cleaning liquid 11 and the recovery efficiency of the mist-like amine. This data was obtained under the test conditions shown below.
-Test equipment inner diameter (corresponding to the inner diameter of the absorption tower container 20c): 157 mm
-Processed gas flow rate (corresponding to the flow rate of decarboxylated combustion exhaust gas 3): 0.7 m / s
-Mist-like amine number concentration (particle size 0.61 μm to 0.95 μm)
・ ・ ・ Approximately 10,000 pieces / cc
・ Washing water mist center particle size ・ ・ ・ Approximately 0.5mm
・ Injection pressure ・ ・ ・ 0.2MPa

As shown in FIG. 2, the recovery efficiency is low in the normal flow rate range of the second cleaning liquid 12 and the third cleaning liquid 13, but the recovery efficiency increases beyond this range. When the flow rate is 300 L / min / m ² or more, the recovery efficiency exceeds 70%, and the recovery efficiency of mist-like amine can be improved.

Further, as described above, the amine accompanying the decarboxylated combustion exhaust gas 3 is roughly classified into a gaseous amine and a mist-like amine, but in general, the mist-like amine has a ratio as an amine amount. There are many. As a result, the first cleaning liquid 11 that first cleans the decarboxylated combustion exhaust gas 3 discharged from the carbon dioxide recovery unit 20a injects from the first injector 21e to recover the mist-like amine, thereby recovering the decarboxylated combustion exhaust gas. It becomes possible to effectively recover the amine associated with 3. In this case, when the second cleaning liquid 12 cleans, the amount of amine accompanying the decarboxylated combustion exhaust gas 3 is reduced, and when the third cleaning liquid 13 cleans, the amount is further reduced. Therefore, the amine concentration of the second cleaning liquid 12 is lower than the amine concentration of the first cleaning liquid 11, and the amine concentration of the third cleaning liquid 13 is further lower than that of the second cleaning liquid 12.

As shown in FIG. 1, the decarboxylated combustion exhaust gas 3 washed with the first cleaning liquid 11 is discharged from the first recovery space 21d of the first cleaning unit 21. Then, the decarboxylated combustion exhaust gas 3 further rises in the absorption tower container 20c and passes through the first cleaning unit outlet demister 82.

The first cleaning unit outlet demister 82 mainly captures the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 and the mist of the first cleaning liquid 11. Of these, the mist-like amine is formed more densely than the recovery unit outlet demister 81 in the first cleaning unit outlet demister 82. Therefore, among the gaseous amines accompanying the decarboxylated combustion exhaust gas 3, the mist-like amine having a large particle size and the mist-like amine having a small particle size are captured by the first cleaning unit outlet demister 82. The mist-like amine that could not be completely recovered in the first recovery space 21d is captured by the first cleaning unit outlet demister 82.

The decarboxylated combustion exhaust gas 3 that has passed through the first cleaning unit outlet demister 82 passes through the second receiving unit 22c of the second cleaning unit 22 and reaches the second recovery unit 22a.

On the other hand, the second cleaning liquid 12 stored in the second receiving portion 22c is extracted from the second receiving portion 22c by the second circulation pump 55 and supplied to the second cleaning liquid disperser 22b through the second circulation line 54. To. During this time, the second cleaning liquid 12 is cooled by the second cleaning liquid cooler 56, and the temperature of the second cleaning liquid 12 becomes lower than the temperature of the first cleaning liquid 11.

In the second recovery unit 22a, the cooled second cleaning liquid 12 comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3 while flowing down the surface of the second recovery unit 22a, and the decarboxylated combustion exhaust gas 3 is cleaned. As a result, the gaseous amine accompanying the decarboxylated combustion exhaust gas 3 is mainly recovered in the second cleaning liquid 12. The second cleaning liquid 12 that has washed the decarboxylated combustion exhaust gas 3 in the second recovery unit 22a falls from the second recovery unit 22a, is received by the second receiving unit 22c, and is stored.

Since the cooled second cleaning liquid 12 is supplied to the second recovery unit 22a, the temperature of the second recovery unit 22a is lower than the temperature of the first recovery space 21d. Therefore, the decarboxylated combustion exhaust gas 3 is cooled by the second cleaning liquid 12, and the temperature of the decarboxylated combustion exhaust gas 3 is lowered. Due to the decrease in temperature of the decarboxylated combustion exhaust gas 3, the water vapor accompanying the decarboxylated combustion exhaust gas 3 is condensed, and the condensed water is captured by the second cleaning liquid 12. As a result, the amine concentration of the second cleaning liquid 12 is reduced.

Further, the mist-like amine that could not be completely recovered by the outlet demister 82 of the first cleaning section is supplied to the second recovery section 22a of the second cleaning section 22 and cooled in the second recovery section 22a. In the second recovery unit 22a, the condensed water is also captured by the mist-like amine. As a result, the particle size of the mist-like amine increases, and the mist-like amine is easily captured by the second cleaning unit outlet demister 83 provided above the second recovery unit 22a.

The decarboxylated combustion exhaust gas 3 washed with the second cleaning liquid 12 is discharged from the second recovery unit 22a, further rises in the absorption tower container 20c, and passes through the second cleaning unit outlet demister 83.

The second cleaning unit outlet demister 83 mainly captures the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 and the mist of the second cleaning liquid 12. Of these, the mist-like amine is formed more densely than the recovery unit outlet demister 81 in the second cleaning unit outlet demister 83. Therefore, among the gaseous amines accompanying the decarboxylated combustion exhaust gas 3, the mist-like amine having a large particle size and the mist-like amine having a small particle size are captured by the second cleaning unit outlet demister 83. The mist-like amine that could not be completely recovered in the first recovery space 21d or the first cleaning section outlet demister 82 is captured by the second cleaning section outlet demister 83.

The decarboxylated combustion exhaust gas 3 that has passed through the second cleaning section outlet demister 83 passes through the third receiving section 23c of the third cleaning section 23 and reaches the third recovery section 23a.

On the other hand, the third cleaning liquid 13 stored in the third receiving portion 23c is extracted from the third receiving portion 23c by the third circulation pump 58 and supplied to the third cleaning liquid disperser 23b through the third circulation line 57. To. During this time, the third cleaning liquid 13 is cooled by the third cleaning liquid cooler 59.

In the third recovery unit 23a, the cooled third cleaning liquid 13 flows down the surface of the third recovery unit 23a and comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3, and the decarboxylated combustion exhaust gas 3 is cleaned. As a result, the gaseous amine accompanying the decarboxylated combustion exhaust gas 3 is mainly recovered in the third cleaning liquid 13. The third cleaning liquid 13 that has washed the decarboxylated combustion exhaust gas 3 in the third recovery unit 23a falls from the third recovery unit 23a, is received by the third receiving unit 23c, and is stored.

Further, when the cooled third cleaning liquid 13 is supplied to the third recovery unit 23a, the temperature of the third recovery unit 23a is lower than the temperature of the second cleaning unit 22. Therefore, the decarboxylated combustion exhaust gas 3 is cooled by the third cleaning liquid 13, and the temperature of the decarboxylated combustion exhaust gas 3 is lowered. Due to the decrease in temperature of the decarboxylated combustion exhaust gas 3, the water vapor accompanying the decarboxylated combustion exhaust gas 3 is condensed, and the condensed water is captured by the third cleaning liquid 13. As a result, the amine concentration of the third cleaning liquid 13 is reduced.

Further, the mist-like amine that could not be completely recovered by the first cleaning section 21 and the second cleaning section 22 is supplied to the third recovery section 23a of the third cleaning section 23 and cooled in the third recovery section 23a. In the third recovery unit 23a, the condensed water is also captured by the mist-like amine. As a result, the particle size of the mist-like amine is increased, and the mist-like amine is easily captured by the third cleaning unit outlet demister 84 provided above the third recovery unit 23a.

The decarboxylated combustion exhaust gas 3 washed with the third cleaning liquid 13 is discharged from the third recovery unit 23a, further rises in the absorption tower container 20c, and passes through the third cleaning unit outlet demister 84.

The third cleaning unit outlet demister 84 mainly captures the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 and the mist of the third cleaning liquid 13. In general, one of the purposes for which the third cleaning unit outlet demister 84 is provided is to back up the second cleaning unit outlet demister 83, and to remove the mist-like amine that could not be completely recovered by the second cleaning unit outlet demister 83. To capture. However, the mist-like amine is captured by the recovery unit outlet demister 81, the first cleaning unit outlet demister 82, and the second cleaning unit outlet demister 83. Therefore, when it can be considered that the mist-like amine is sufficiently captured by the second cleaning unit outlet demister 83, the target of the third cleaning unit outlet demister 84 can be narrowed down to the mist of the third cleaning liquid 13. The mist derived from the third cleaning liquid 13 tends to have a larger particle size than the mist-like amine. Therefore, in consideration of the pressure loss of the decarboxylated combustion exhaust gas 3, the third cleaning section outlet demister 84 is sparsely formed.

The decarboxylated combustion exhaust gas 3 that has passed through the third cleaning unit outlet demister 84 is discharged from the top of the absorption tower container 20c.

As described above, according to the present embodiment, the first cleaning unit 21 has a second injector 22e that injects and drops the first cleaning liquid 11. As a result, the first cleaning liquid 11 can be turned into mist, and the mist of the first cleaning liquid 11 physically collides with the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 discharged from the carbon dioxide recovery unit 20a. be able to. Therefore, the mist-like amine can be efficiently recovered in the first cleaning liquid 11, and the cleaning efficiency of the decarboxylated combustion exhaust gas 3 can be improved. As a result, the amount of amine released into the atmosphere can be reduced.

Further, according to the present embodiment, the decarboxylated combustion exhaust gas 3 and the gas / liquid while the first cleaning liquid 11 freely falls in a mist state from the first injector 21e of the first cleaning unit 21 to the first receiving unit 21c. A first recovery space 21d that comes into contact is formed. This makes it possible to prevent the mist of the first cleaning liquid 11 ejected from the first injector 21e from colliding with a member such as a structure before reaching the first receiving portion 21c. Therefore, it is possible to prevent the mist of the first cleaning liquid 11 from being miniaturized and accompanying the decarboxylated combustion exhaust gas 3.

Further, according to the present embodiment, the flow rate (first flow rate) per unit area and unit time of the first cleaning liquid 11 injected from the first injector 21e of the first cleaning unit 21 is the second cleaning unit 22. It is larger than the flow rate per unit area and unit time (second flow rate) of the second cleaning liquid 12 dispersed from the second cleaning liquid disperser 22b. As a result, the number of mists of the first cleaning liquid 11 injected from the first injector 21e can be increased, and the probability of physical collision with the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 can be increased. .. Therefore, the mist-like amine can be recovered more efficiently.

Further, according to the present embodiment, the first pressure of the first cleaning liquid 11 supplied to the first injector 21e of the first cleaning unit 21 is supplied to the second cleaning liquid disperser 22b of the second cleaning unit 22. It is higher than the second pressure of the second cleaning liquid 12. As a result, it is possible to increase the initial velocity in the first vertical direction, which is a velocity component in the vertical direction, among the injection velocities of the mist of the first cleaning liquid 11 from the first injector 21e. Therefore, the mist of the first cleaning liquid 11 can be quickly and uniformly supplied into the first recovery space 21d, and the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 can be efficiently recovered. Further, it is possible to prevent the mist of the first cleaning liquid 11 from being accompanied by the decarboxylated combustion exhaust gas 3.

Further, according to the present embodiment, the third cleaning unit outlet demister 84 is formed more sparsely than the second cleaning unit outlet demister 83. As a result, while the mist-like amine and the mist of the third cleaning liquid 13 are captured by the third cleaning unit outlet demister-84, the pressure loss generated in the flow of the decarboxylated combustion exhaust gas 3 passing through the third cleaning unit outlet demister 84. Can be reduced. In this case, the power of the blower B for supplying the combustion exhaust gas 2 to the absorption tower 20 can be reduced.

Further, according to the present embodiment, the recovery unit outlet demister 81 is formed more sparsely than the second cleaning unit outlet demister 83. As a result, it is possible to reduce the pressure loss generated in the flow of the decarboxylated combustion exhaust gas 3 passing through the recovery unit outlet demister 81 while capturing the mist-like amine by the recovery unit outlet demister 81. In this case, the power of the blower B for supplying the combustion exhaust gas 2 to the absorption tower 20 can be reduced.

In the above-described embodiment, the recovery unit outlet demister 81 and the third cleaning unit outlet demister 84 are formed more sparsely than the first cleaning unit outlet demister 82 and the second cleaning unit outlet demister 83, respectively. An example was explained. However, the present invention is not limited to this, and each demister 81 to 84 may be formed with the same porosity or removal rate. The same applies to each embodiment described later.

Further, in the above-described embodiment, the first injector 21e of the first cleaning unit 21 is configured as a so-called one fluid nozzle in which the first cleaning liquid 11 with increased pressure is ejected from the spray nozzle hole. I explained an example. However, the present invention is not limited to this, and the first injector 21e may be configured as a two-fluid nozzle as long as the first cleaning liquid 11 can be injected. In this case, if the first cleaning liquid 11 can be sprayed, the pressure of the first cleaning liquid 11 supplied to the first injector 21e may be lower than 0.1 MPa.

(Second embodiment)
Next, the carbon dioxide recovery system and the operation method of the carbon dioxide recovery system according to the second embodiment of the present invention will be described with reference to FIG.

The second embodiment shown in FIG. 3 is mainly different in that a first heater for heating the first cleaning liquid is provided, and the other configurations are the first embodiment shown in FIGS. 1 and 2. It is almost the same as the form of. In FIG. 3, the same parts as those of the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, as shown in FIG. 3, the first circulation line 50 is provided with a first heater 52 (first heating unit) for heating the first cleaning liquid 11. The first heater 52 raises the temperature of the first cleaning liquid 11 to be higher than the temperature of the upper end portion of the carbon dioxide recovery unit 20a and higher than the temperature of the second cleaning liquid 12. In the embodiment shown in FIG. 3, the first heater 52 is provided on the downstream side (the side of the first injector 21e) of the first circulation pump 51 in the first circulation line 50, but this is limited to this. It will never be done.

The heat source for heating the first cleaning liquid 11 in the first heater 52 is the lean liquid 5 discharged from the regeneration tower 30 and passing through the heat exchanger 31. That is, in the present embodiment, the lean liquid 5 that has passed through the heat exchanger 31 is supplied to the first heater 52 to heat the first cleaning liquid 11.

As described above, the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 is difficult to recover by cleaning using a cleaning liquid and a packed bed or the like. Therefore, in the present embodiment, the mist of the first cleaning liquid 11 ejected from the first injector 21e of the first cleaning unit 21 is made to collide with the mist-like amine, and the mist-like amine is made into the mist of the first cleaning liquid 11. It is collected in. However, when the particle size of the mist-like amine becomes smaller (for example, when it becomes 0.5 μm or less), the recovery efficiency of the mist-like amine decreases. Therefore, in order to increase the recovery efficiency of the mist-like amine, it is effective to increase the particle size of the mist-like amine.

As a method of increasing the particle size of the mist-like amine, it is conceivable to lower the temperature of the second cleaning unit 22 to be lower than the temperature of the first cleaning unit 21 to widen the temperature difference between the two. In this case, when the decarboxylated combustion exhaust gas 3 passes through the second cleaning unit 22, it is cooled, the water vapor contained in the decarboxylated combustion exhaust gas 3 is condensed, and the condensed water is captured by the mist-like amine and becomes mist-like. The particle size of the amine can be increased.

There are two conceivable methods for lowering the temperature of the second cleaning unit 22 than the temperature of the first cleaning unit 21. The first is a method of heating the first cleaning unit 21, and the second is a method of cooling the second cleaning unit 22.

The cleaning solution may be cooled for the purpose of reducing the amine vapor pressure in the cleaning solution. However, while the operating temperature of a general cleaning liquid is about 30 ° C. to 40 ° C., the temperature of the cooled cleaning liquid remains at about 20 ° C. to 30 ° C., and the temperature difference obtained by cooling becomes small. For this reason, it is difficult to increase the temperature difference between the first cleaning unit 21 and the second cleaning unit 22 by cooling the second cleaning liquid 12. Further, when the second cleaning liquid 12 is cooled by using a chiller having a high cooling capacity in order to widen the temperature difference, the temperature of the cleaning liquid can be further lowered, but the energy required for cooling increases sharply. .. One of the major issues of the carbon dioxide recovery system 1 is how to reduce the energy required to recover carbon dioxide. Therefore, it is not preferable to increase the energy for cooling the decarboxylated combustion exhaust gas 3.

Therefore, in the present embodiment, waste heat from the outside (peripheral equipment) of the carbon dioxide capture system 1 is utilized. That is, the temperature of the first cleaning liquid 11 is raised by heating the first cleaning liquid 11 which is normally used at room temperature or after being cooled with waste heat, and the temperature difference between the first cleaning liquid 11 and the second cleaning liquid 12 is widened. I'm letting you. As a result, the temperature difference between the first cleaning unit 21 and the second cleaning unit 22 is widened, and the amount of condensed water in the second cleaning unit 22 is increased. The temperature of the first cleaning unit 21 is preferably 5 ° C. to 50 ° C. higher than the temperature at the upper end of the carbon dioxide recovery unit 20a, and even more preferably 10 ° C. to 30 ° C.

In addition to increasing the particle size of the mist-like amine by condensation, by actively generating condensed water, the following two problems of the cleaning method using a cleaning liquid and a packed bed can be solved. .. First, the problems of the cleaning method using the cleaning liquid and the packed bed will be described.

[1] The cleaning liquid flowing down the surface of the packed bed tends to flow unevenly. As a result, the entire surface of the packed bed does not get wet (short pass occurs), so that there is a problem that the decarboxylated combustion exhaust gas 3 does not come into contact with the cleaning liquid and slips through the packed layer without being washed.

[2] The cleaning liquid flowing down the surface of the packed bed absorbs the gaseous amine accompanying the decarboxylated combustion exhaust gas 3, and the absorption rate is the amine concentration of the cleaning liquid at the gas-liquid contact interface and the decarboxylated combustion exhaust gas. It depends on the amine concentration of 3. That is, if the amine concentration of the cleaning liquid at the gas-liquid contact interface can always be maintained at a low concentration, the rate at which the cleaning liquid absorbs amine can be maintained high. However, the amine concentration of the cleaning liquid at the gas-liquid contact interface increases immediately by absorbing the amine in the decarboxylated combustion exhaust gas 3. Since the diffusion rate of amines in the cleaning liquid is slow, the amines absorbed in the cleaning liquid at the gas-liquid contact interface are difficult to diffuse into the cleaning liquid. Therefore, there is a problem that the amine concentration of the cleaning liquid at the gas-liquid contact interface is maintained at a high concentration, which causes a decrease in the amine absorption rate.

In the present embodiment, as described above, the above-mentioned two title changes are solved by positively utilizing the condensed water.

[1] Condensation is generated from the decarboxylated combustion exhaust gas 3 flowing through the voids of the packed bed. The decarboxylated combustion exhaust gas 3 flows uniformly through the packed bed. Therefore, the surface of the packed bed can be uniformly wetted by the condensed water, and the decarboxylated combustion exhaust gas 3 can be prevented from slipping through the packed bed without being washed.

[2] By increasing the amount of condensed water, the condensed water is captured by the cleaning liquid. This replaces the gas-liquid contact interface of the cleaning liquid with the condensed moisture while the condensation is occurring. Therefore, the amine concentration of the cleaning liquid at the gas-liquid contact interface can be maintained at a low concentration, and the decrease in the amine absorption rate can be suppressed.

In this way, the above-mentioned two problems can be solved, the absorption rate of amine from the decarboxylated combustion exhaust gas 3 can be increased, the amine can be effectively captured, and the decrease in the amount of amine recovered can be suppressed. ..

In the present embodiment shown in FIG. 3, in the first cleaning unit 21, the mist of the first cleaning liquid 11 heated by the first heater 52 is injected from the first injector 21e and accompanies the decarboxylated combustion exhaust gas 3. Mist-like amine is recovered. The mist-like amine that could not be completely recovered by the first cleaning unit 21 is heated by the first cleaning liquid 11, supplied to the second recovery unit 22a of the second cleaning unit 22, and then cooled. As a result, in the second recovery unit 22a, a large amount of water is condensed from the water vapor accompanying the decarboxylated combustion exhaust gas 3, and a large amount of water is captured by the mist-like amine. Therefore, the particle size of the mist-like amine increases, and the mist-like amine is easily captured by the second cleaning unit outlet demister 83 provided above the second recovery unit 22a. Further, in the second recovery unit 22a, since the above-mentioned problems [1] and [2] are solved, the gaseous amine accompanying the decarboxylated combustion exhaust gas 3 can be effectively recovered.

As described above, according to the present embodiment, since the decarboxylated combustion exhaust gas 3 is heated in the first cleaning unit 21, the temperature difference between the first cleaning unit 21 and the second cleaning unit 22 can be widened. As a result, the particle size of the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 can be increased in the second cleaning unit 22, and the mist-like amine can be efficiently captured by the second cleaning unit outlet demister 83. can. In particular, in the present embodiment, since the heated first cleaning liquid 11 is sprayed, it is possible to equalize the heating of the decarboxylated combustion exhaust gas 3 passing through the first recovery space 21d. Therefore, the temperature of the decarboxylated combustion exhaust gas 3 discharged from the first recovery space 21d can be uniformly raised, and the condensation of water in the second cleaning unit 22 can be promoted. As a result, the cleaning efficiency of the decarboxylated combustion exhaust gas 3 can be improved.

Further, according to the present embodiment, the heat source of the first heater 52 is the lean liquid 5 discharged from the regeneration tower 30 and passing through the heat exchanger 31. As a result, the temperature of the first cleaning liquid 11 can be made higher than the temperature of the upper end portion of the carbon dioxide recovery unit 20a and higher than the temperature of the second cleaning liquid 12. Therefore, the temperature difference between the first cleaning unit 21 and the second cleaning unit 22 can be increased. Further, since the lean liquid 5 that has passed through the heat exchanger 31 is used as the heat source for expanding such a temperature difference, waste heat can be effectively used.

In the above-described embodiment, the example in which the heat source of the first heater 52 is the lean liquid 5 that has passed through the heat exchanger 31 discharged from the regeneration tower 30 has been described. However, the present invention is not limited to this, and the heat source of the first heater 52 is arbitrary as long as the temperature of the first cleaning liquid 11 can be made higher than the temperature of the second cleaning liquid 12. For example, it may be the heating medium 6 discharged from the reboiler 33, or the combustion exhaust gas 2 supplied to the absorption tower 20. In either case, the first cleaning liquid 11 can be heated by effectively utilizing the waste heat. Of these, the combustion exhaust gas 2 is usually supplied from the boiler of a thermal power plant to the absorption tower 20 of the carbon dioxide recovery system 1 after passing through a denitration device, a dust removal device, a desulfurization device, and the like, and is decarboxylated. Since the temperature of the combustion exhaust gas 2 before being supplied to the absorption tower 20 has heat of about 50 ° C. to 90 ° C., this waste heat can be effectively used. Further, the heat source of the first heater 52 may be an electric heater.

(Third embodiment)
Next, the carbon dioxide recovery system and the operation method of the carbon dioxide recovery system according to the third embodiment of the present invention will be described with reference to FIG.

The third embodiment shown in FIG. 4 is mainly different in that a second heater for further heating the first cleaning liquid heated by the first heater is provided, and the other configurations are shown in FIG. It is substantially the same as the second embodiment shown in. In FIG. 4, the same parts as those of the second embodiment shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, as shown in FIG. 4, a second heater 53 (second heating unit) for further heating the first cleaning liquid 11 heated by the first heater 52 is provided on the first circulation line 50. Has been done. In the embodiment shown in FIG. 4, the second heater 53 is provided on the downstream side (the side of the first injector 21e) of the first heater 52 in the first circulation line 50.

The heat source for heating the first cleaning liquid 11 in the second heater 53 is different from the heat source of the first heater 52, and is the heating medium 6 discharged from the reboiler 33. That is, in the present embodiment, the heating medium 6 discharged from the reboiler 33 is supplied to the second heater 53 to further heat the first cleaning liquid 11 heated in the first heater 52. There is. Since the temperature of the heating medium 6 that has passed through the reboiler 33 is higher than the temperature of the lean liquid 5 discharged from the heat exchanger 31, the heating medium 6 causes the first cleaning liquid 11 heated by the first heater 52 to be heated. It can be further heated. Therefore, the temperature of the first cleaning liquid 11 can be further increased.

As described above, according to the present embodiment, the second heater 53 further heats the first cleaning liquid 11 heated by the first heater 52. As a result, the temperature of the first cleaning liquid 11 can be further increased, and the temperature difference between the first cleaning unit 21 and the second cleaning unit 22 can be further increased. Therefore, the particle size of the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 can be further increased in the second cleaning unit 22, and the mist-like amine can be captured more efficiently by the second cleaning unit outlet demister 83. can do. As a result, the cleaning efficiency of the decarboxylated combustion exhaust gas 3 can be further improved.

Further, according to the present embodiment, the heat source of the second heater 53 is the heating medium 6 discharged from the reboiler 33. As a result, the temperature difference between the first cleaning unit 21 and the second cleaning unit 22 can be increased by effectively utilizing the waste heat.

In the above-described embodiment, the example in which the heat source of the second heater 53 is the heating medium 6 discharged from the reboiler 33 has been described. However, the present invention is not limited to this, and the heat source of the second heater 53 is arbitrary as long as the first cleaning liquid 11 can be further heated. For example, it may be the combustion exhaust gas 2 supplied to the absorption tower 20. Further, the heat source of the second heater 53 may be an electric heater.

(Fourth Embodiment)
Next, the carbon dioxide recovery system and the operation method of the carbon dioxide recovery system according to the fourth embodiment of the present invention will be described with reference to FIG.

In the fourth embodiment shown in FIG. 5, a first bypass line for mixing a part of the second cleaning liquid with the first cleaning liquid is provided, and a second bypass line for mixing a part of the third cleaning liquid with the second cleaning liquid is provided. The main difference is that the bypass line is provided, and the other configurations are substantially the same as those of the second embodiment shown in FIG. In FIG. 5, the same parts as those of the second embodiment shown in FIG. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, as shown in FIG. 5, a first bypass line 61 for mixing a part of the second cleaning liquid 12 into the first cleaning liquid 11 is provided. FIG. 5 shows an example in which the upstream end portion (the end portion on the side of the second cleaning portion 22) of the first bypass line 61 is connected to the second receiving portion 22c of the second cleaning portion 22. As a result, a part of the second cleaning liquid 12 stored in the second receiving portion 22c flows into the first bypass line 61. An example is shown in which the downstream end portion (the end portion on the side of the first cleaning portion 21) of the first bypass line 61 is arranged in the upper vicinity of the first receiving portion 21c of the first cleaning portion 21. As a result, the second cleaning liquid 12 that has passed through the first bypass line 61 is supplied to the first receiving portion 21c.

The first bypass line 61 may be provided with a first bypass valve 63. For example, the first bypass valve 63 may be controlled based on the liquid level of the second cleaning liquid 12 stored in the second receiving portion 22c. In this case, when the liquid level meter (not shown) is provided in the second receiving portion 22c and the liquid level of the second cleaning liquid 12 stored in the second receiving portion 22c is higher than a predetermined reference level. May increase the opening degree of the first bypass valve 63 and decrease the opening degree of the first bypass valve 63 when it is lower than a predetermined reference level. Further, the opening degree of the first bypass valve 63 may be adjusted according to the liquid level of the second cleaning liquid 12.

Further, in the present embodiment, as shown in FIG. 5, a second bypass line 62 for mixing a part of the third cleaning liquid 13 into the second cleaning liquid 12 is provided. FIG. 5 shows an example in which the upstream end portion of the second bypass line 62 (the end portion on the side of the third cleaning portion 23) is connected to the third receiving portion 23c of the third cleaning portion 23. As a result, a part of the third cleaning liquid 13 stored in the third receiving portion 23c flows into the second bypass line 62. An example is shown in which the downstream end portion of the second bypass line 62 (the end portion on the side of the second cleaning portion 22) is arranged in the upper vicinity of the second receiving portion 22c of the second cleaning portion 22. As a result, the third cleaning liquid 13 that has passed through the second bypass line 62 is supplied to the second receiving portion 22c.

The second bypass line 62 may be provided with a second bypass valve 64. For example, the second bypass valve 64 may be controlled based on the liquid level of the third cleaning liquid 13 stored in the third receiving portion 23c. In this case, when the liquid level meter (not shown) is provided in the third receiving portion 23c and the liquid level of the third cleaning liquid 13 stored in the third receiving portion 23c is higher than a predetermined reference level. May increase the opening degree of the second bypass valve 64 and decrease the opening degree of the second bypass valve 64 when it is lower than a predetermined reference level. Further, the opening degree of the second bypass valve 64 may be adjusted according to the liquid level of the third cleaning liquid 13.

As described above, according to the present embodiment, a part of the second cleaning liquid 12 having an amine concentration lower than that of the first cleaning liquid 11 can be mixed with the first cleaning liquid 11 by the first bypass line 61. As a result, the amine concentration of the first cleaning liquid 11 can be reduced, and the amine recovery performance of the first cleaning unit 21 can be prevented from deteriorating. Further, since the second cleaning liquid 12 can be reused as the first cleaning liquid 11, it is not necessary to dispose of the second cleaning liquid 12, and the frequency of replenishing the first cleaning liquid 11 with new cleaning liquid can be reduced.

Further, according to the present embodiment, a part of the third cleaning liquid 13 having a lower amine concentration than the second cleaning liquid 12 can be mixed with the second cleaning liquid 12 by the second bypass line 62. As a result, the amine concentration of the second cleaning liquid 12 can be reduced, and the amine recovery performance of the second cleaning unit 22 can be prevented from deteriorating. Further, since the third cleaning liquid 13 can be reused as the second cleaning liquid 12, it is not necessary to dispose of the third cleaning liquid 13, and the frequency of replenishing the second cleaning liquid 12 with new cleaning liquid can be reduced.

In the above-described embodiment, as shown in FIG. 5, an example in which the first heater 52 is provided in the first circulation line 50 is shown. However, the present invention is not limited to this, and the first heater 52 may not be provided.

Further, in the above-described embodiment, as shown in FIG. 5, an example in which a second bypass line 62 for mixing a part of the third cleaning liquid 13 into the second cleaning liquid 12 is provided has been described. However, the present invention is not limited to this, and such a second bypass line 62 may not be provided.

(Fifth Embodiment)
Next, the carbon dioxide recovery system and the operation method of the carbon dioxide recovery system according to the fifth embodiment of the present invention will be described with reference to FIG.

In the fifth embodiment shown in FIG. 6, the first cleaning liquid cleans the decarboxylated combustion exhaust gas while flowing down the surface of the first recovery unit, and the second cleaning liquid drops the recovery space in a mist state to remove the exhaust gas. The main difference is that the carbonic acid combustion exhaust gas is cleaned, and the other configurations are substantially the same as those of the first embodiment shown in FIGS. 1 and 2. In FIG. 6, the same parts as those of the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, as shown in FIG. 6, generally, the first cleaning unit 21 shown in FIG. 1 is provided above the second cleaning unit 22 shown in FIG. 1.

More specifically, the first cleaning unit 21 has a first recovery unit 21a (packed bed or the like) and a first cleaning liquid disperser 21b provided above the first recovery unit 21a. That is, the first recovery unit 21a is provided in place of the first recovery space 21d, and the first cleaning liquid disperser 21b is provided in place of the first injector 21e. The first recovery unit 21a is configured as a countercurrent gas-liquid contact device like the second recovery unit 22a and the third recovery unit 23a. That is, the first recovery unit 21a is composed of a packing layer or the like as an example, and decarboxylates while flowing the first cleaning liquid 11 onto the surface of an internal structure for increasing the gas-liquid contact area of the filled filling or particles. The amine (mainly gaseous amine) accompanying the decarboxylated combustion exhaust gas 3 is recovered by contacting the combustion exhaust gas 3 with gas and liquid, and the amine is removed from the decarboxylated combustion exhaust gas 3. Similar to the second cleaning liquid disperser 22b and the third cleaning liquid disperser 23b, the first cleaning liquid disperser 21b disperses and drops the first cleaning liquid 11 toward the first recovery unit 21a, and drops the first cleaning liquid disperser 21a. The first cleaning liquid 11 is supplied so as to flow down the surface of the internal structure. The first cleaning liquid disperser 21b free-falls the first cleaning liquid 11 onto the first recovery unit 21a by the action of gravity. The first cleaning liquid 11 that has flowed down the surface of the internal structure in the first recovery unit 21a is received and stored in the first receiving unit 21c.

The second cleaning unit 22 has a second recovery space 22d and a second injector 22e provided above the second recovery space 22d.

In the second recovery space 22d, similarly to the first recovery space 21d, the second cleaning liquid 12 ejected from the second injector 22e freely drops in a mist state (that is, comes into contact with the surface of a structure or the like in the space). It is a space in which the decarboxylated combustion exhaust gas 3 that rises through the second receiving portion 22c and rises in gas-liquid contact while falling without any trouble), and is an amine (mainly mist-like) accompanying the decarboxylated combustion exhaust gas 3. It is a space to collect amine). The second recovery space 22d is formed from the second injector 22e to the second receiving portion 22c. Since the second recovery space 22d is configured in the same manner as the first recovery space 21d of the first cleaning unit 21 described above, detailed description thereof will be omitted here. Since the second injector 22e is configured in the same manner as the first injector 21e of the first cleaning unit 21 described above, detailed description thereof will be omitted here.

The decarboxylated combustion exhaust gas 3 that has passed through the recovery unit outlet demister 81 passes through the first receiving unit 21c of the first cleaning unit 21 and reaches the first recovery unit 21a of the first cleaning unit 21.

On the other hand, the first cleaning liquid 11 stored in the first receiving portion 21c is extracted from the first receiving portion 21c by the first circulation pump 51 and supplied to the first cleaning liquid disperser 21b through the first circulation line 50. To. In the present embodiment, since the first circulation line 50 is not provided with the heaters 52, 53 and the cooler described later, the first cleaning liquid 11 passing through the first circulation line 50 is positively used. It is neither heated nor cooled.

In the first recovery unit 21a, the first cleaning liquid 11 flows down the surface of the first recovery unit 21a and comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3, and the decarboxylated combustion exhaust gas 3 is cleaned. As a result, the gaseous amine accompanying the decarboxylated combustion exhaust gas 3 is mainly recovered in the first cleaning liquid 11. The first cleaning liquid 11 that has washed the decarboxylated combustion exhaust gas 3 in the first recovery unit 21a falls from the first recovery unit 21a, is received by the first receiving unit 21c, and is stored.

The decarboxylated combustion exhaust gas 3 washed with the first cleaning liquid 11 is discharged from the first recovery unit 21a, further rises in the absorption tower container 20c, and passes through the first cleaning unit outlet demister 82.

The first cleaning unit outlet demister 82 mainly captures the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 and the mist of the first cleaning liquid 11. The decarboxylated combustion exhaust gas 3 that has passed through the first cleaning unit outlet demister 82 passes through the second receiving unit 22c of the second cleaning unit 22 and reaches the second recovery unit 22a.

On the other hand, the second cleaning liquid 12 stored in the second receiving portion 22c is extracted from the second receiving portion 22c by the second circulation pump 55 and supplied to the second cleaning liquid disperser 22b through the second circulation line 54. To. During this time, the second cleaning liquid 12 is cooled by the second cleaning liquid cooler 56, and the temperature of the second cleaning liquid 12 becomes lower than the temperature of the first cleaning liquid 11.

The second cleaning liquid 12 is sprayed from the spray nozzle hole of the second injector 22e, falls in the second recovery space 22d, and reaches the second receiving portion 22c directly. During this time, the second cleaning liquid 12 comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3 while falling in a mist state, and the decarboxylated combustion exhaust gas 3 is washed with the second cleaning liquid 12. As a result, the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 is recovered in the second cleaning liquid 12. The second cleaning liquid 12 that has reached the second receiving portion 22c is received and stored in the second receiving portion 22c.

In the second recovery space 22d, the cooled second cleaning liquid 12 is sprayed from the second injector 22e, so that the temperature of the second recovery space 22d is lower than the temperature of the first recovery unit 21a. Therefore, the decarboxylated combustion exhaust gas 3 is cooled by the second cleaning liquid 12, and the temperature of the decarboxylated combustion exhaust gas 3 is lowered. Due to the decrease in temperature of the decarboxylated combustion exhaust gas 3, the water vapor accompanying the decarboxylated combustion exhaust gas 3 is condensed, and the condensed water is captured by the second cleaning liquid 12. As a result, the particle size of the mist-like amine increases, and the mist-like amine is captured by the second cleaning unit outlet demister 83 provided above the second recovery space 22d. Further, in the second recovery space 22d, the cooled second cleaning liquid 12 is injected, so that the cooling of the decarboxylated combustion exhaust gas 3 passing through the second recovery space 22d can be equalized. Therefore, the condensation to the mist-like amine can be promoted, and the increase in the particle size of the mist-like amine can be equalized. Further, since the mist-like amine having an increased particle size can be removed by the second cleaning liquid 12 ejected from the second injector 22e in the second recovery space 22d, the recovery efficiency can be improved.

As described above, according to the present embodiment, the second cleaning unit 22 has the second recovery space 22d and the second injector 22e. As a result, the second cleaning liquid 12 can be turned into mist, and the mist of the second cleaning liquid 12 physically collides with the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 discharged from the first cleaning unit 21. be able to. Therefore, the mist-like amine can be efficiently recovered in the second cleaning liquid 12, and the cleaning efficiency of the decarboxylated combustion exhaust gas 3 can be improved. In particular, since the second cleaning liquid 12 is cooled by the second cleaning liquid cooler 56, the cooling of the decarboxylated combustion exhaust gas 3 can be equalized. Therefore, the condensation on the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 can be uniformly promoted, and the increase in the particle size of the mist-like amine can be equalized. In this case, the mist-like amine can be efficiently captured by the second cleaning unit outlet demister 83, and the amount of the amine released into the atmosphere can be reduced.

(Sixth Embodiment)
Next, the carbon dioxide recovery system and the operation method of the carbon dioxide recovery system according to the sixth embodiment of the present invention will be described with reference to FIGS. 7 to 9.

The sixth embodiment shown in FIGS. 7 to 9 is mainly different in that the first cleaning unit outlet demister is not provided, and the other configurations are the first embodiment shown in FIGS. 1 and 2. It is almost the same as the form. In FIGS. 7 to 9, the same parts as those of the first embodiment shown in FIGS. 1 and 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the present embodiment, as shown in FIG. 7, the first cleaning unit 21 recovers the amine by causing gas-liquid contact with the decarboxylated combustion exhaust gas 3 while flowing the first cleaning liquid 11 onto the surface. It has (a packed bed or the like) and a first cleaning liquid disperser 21b that disperses and drops the first cleaning liquid 11 toward the first recovery unit 21a. That is, the first recovery unit 21a is provided in place of the first recovery space 21d, and the first cleaning liquid disperser 21b is provided in place of the first injector 21e. Since the first cleaning unit 21 has the same configuration as that of the fifth embodiment shown in FIG. 6, detailed description thereof will be omitted here.

Further, as shown in FIG. 7, the first cleaning unit outlet demister 82 as shown in FIG. 1 and the like is not provided between the first cleaning unit 21 and the second cleaning unit 22. As a result, the decarboxylated combustion exhaust gas 3 discharged from the first cleaning unit 21 is directly supplied to the second cleaning unit 22.

Therefore, in the present embodiment, the recovery efficiency of the mist-like amine is improved by devising the arrangement of the demister. That is, in the present embodiment, the collection unit outlet demister 81, the second cleaning unit outlet demister 83, and the third cleaning unit outlet demister 84 are provided, but the first cleaning unit outlet demister 82 is not provided.

Here, the characteristics of the change in the particle size of the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 in the absorption tower container 20c will be described with reference to FIG. FIG. 8 is a graph showing the transition of the particle size of the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 in the absorption tower container 20c. The horizontal axis indicates the height position in the absorption tower container 20c as a dimensionless number. In FIG. 8, none of the demisters are arranged, and the particle size of each cleaning unit 21 to 23 has a recovery unit for flowing cleaning liquids 11 to 13 on the surface of the internal structure. It shows a change.

The particle size of the mist-like amine accompanying the decarboxylated combustion exhaust gas 3 gradually increases in the carbon dioxide recovery unit 20a.

The decarboxylated combustion exhaust gas 3 discharged from the carbon dioxide recovery unit 20a and reaching the first cleaning unit 21 is cleaned with the first cleaning liquid 11, and the water concentration of the first cleaning liquid 11 is higher than that of the lean liquid 5. .. Therefore, in the first cleaning unit 21, the partial pressure of water vapor is higher than that of the carbon dioxide recovery unit 20a due to the vapor-liquid equilibrium relationship. This causes condensation to the mist-like amine and increases the particle size of the mist-like amine. In particular, in the first cleaning unit 21, the condensation rate to the mist-like amine is higher than that in the second cleaning unit 22 and the third cleaning unit 23, which will be described later, and the increase in the particle size of the mist-like amine is promoted.

The decarboxylated combustion exhaust gas 3 discharged from the first cleaning unit 21 and reaching the second cleaning unit 22 is cleaned with the second cleaning liquid 12, but the water concentration of the second cleaning liquid 12 is higher than that of the first cleaning liquid 11. expensive. Therefore, in the second cleaning unit 22, the partial pressure of water vapor is higher than that in the first cleaning unit 21 due to the vapor-liquid equilibrium relationship. This causes condensation to the mist-like amine and increases the particle size of the mist-like amine. However, the rate of increase in the particle size of the mist-like amine in the second cleaning unit 22 is smaller than that in the first cleaning unit 21. The reason for this is that although the partial pressure of water vapor in the second cleaning unit 22 is higher than that of the first cleaning unit 21, the difference in the partial pressure of water vapor between the first cleaning unit 21 and the second cleaning unit 22 is not so large, and carbon dioxide is used. It is smaller than the difference in the partial pressure of water vapor between the carbon recovery unit 20a and the first cleaning unit 21. Another reason is that the degree of increase in particle size when condensation to mist-like amine occurs becomes smaller as the particle size of mist-like amine increases when compared with the same amount of condensation. In this way, the increase in the particle size of the mist-like amine in the second cleaning unit 22 becomes slower than that in the first cleaning unit 21.

The decarboxylated combustion exhaust gas 3 discharged from the second cleaning unit 22 and reaching the third cleaning unit 23 is cleaned with the third cleaning liquid 13, and the water concentration of the third cleaning liquid 13 is higher than that of the second cleaning liquid 12. expensive. Therefore, in the third cleaning unit 23, the partial pressure of water vapor is higher than that in the second cleaning unit 22 due to the vapor-liquid equilibrium relationship. This causes condensation to the mist-like amine and increases the particle size of the mist-like amine. However, for the same reason as described in the explanation of the second cleaning unit 22, the rate of increase in the particle size of the mist-like amine in the third cleaning unit 23 is smaller than that in the second cleaning unit 22. Therefore, the increase in the particle size of the mist-like amine in the third cleaning unit 23 is slower than that in the second cleaning unit 22.

Based on such a change in the particle size of the mist-like amine, the first cleaning unit outlet demister 82 is not provided in the present embodiment. That is, according to FIG. 8, the particle size of the mist-like amine in the first cleaning unit 21 is generally 5 μm or less, which is a particle size that is difficult to be captured by the demister. When the first cleaning unit outlet demister 82 is not provided, a mist-like amine having a small particle size is sent to the second cleaning unit 22, and the particle size is increased in the second cleaning unit 22 as shown in FIG. be able to. According to FIG. 8, since the mist-like amine increases to 5 μm or more in the second washing section 22, it grows to a particle size that is easily captured by the demister. Therefore, the mist-like amine can be efficiently recovered by the second cleaning unit outlet demister 83. As described above, in consideration of efficient recovery of the mist-like amine, the first cleaning unit outlet demister 82 is not provided in the present embodiment. In this case, the pressure loss generated in the flow of the decarboxylated combustion exhaust gas 3 in the absorption tower container 20c can be reduced, and the power of the blower B (see FIG. 1) described above can be reduced.

As described above, according to the present embodiment, the first cleaning unit outlet demister 82 is not provided between the first cleaning unit 21 and the second cleaning unit 22, and is discharged from the first cleaning unit 21. The decarboxylated combustion exhaust gas 3 is directly supplied to the second cleaning unit 22 without passing through the demister. As a result, the mist-like amine having a small particle size can be sent to the second cleaning unit 22 to grow, and the particle size can be increased in the second cleaning unit 22 until it is easily captured by the demister. Therefore, the mist-like amine having an increased particle size can be efficiently recovered in the second cleaning unit outlet demister 83. As a result, the cleaning efficiency of the decarboxylated combustion exhaust gas 3 can be improved, and the amount of amine released into the atmosphere can be reduced.

Further, also in the present embodiment, the third cleaning unit outlet demister 84 is formed more sparsely than the second cleaning unit outlet demister 83. As a result, while the mist-like amine and the mist of the third cleaning liquid 13 are captured by the third cleaning unit outlet demister-84, the pressure loss generated in the flow of the decarboxylated combustion exhaust gas 3 passing through the third cleaning unit outlet demister 84. Can be reduced. In this case, the power of the blower B for supplying the combustion exhaust gas 2 to the absorption tower 20 can be reduced.

Further, also in the present embodiment, the recovery unit outlet demister 81 is formed more sparsely than the second cleaning unit outlet demister 83. As a result, it is possible to reduce the pressure loss generated in the flow of the decarboxylated combustion exhaust gas 3 passing through the recovery unit outlet demister 81 while capturing the mist-like amine by the recovery unit outlet demister 81. In this case, the power of the blower B for supplying the combustion exhaust gas 2 to the absorption tower 20 can be reduced.

In the above-described embodiment, the first cleaning unit 21 has the first recovery unit 21a that recovers the amine by contacting the decarboxylated combustion exhaust gas 3 with the decarboxylated combustion exhaust gas 3 while flowing the first cleaning liquid 11 on the surface. An example having a first cleaning liquid disperser 21b for dispersing and dropping the first cleaning liquid 11 toward the first recovery unit 21a has been described. However, the present invention is not limited to this, and as shown in FIG. 9, in the first cleaning unit 21, the first cleaning liquid 11 is in a mist state, as in the first embodiment shown in FIGS. 1 and 2. It is configured to have a first recovery space 21d that comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3 while falling, and a first injector 21e that injects the first cleaning liquid 11 toward the first recovery space 21d. May be good. Even in this case, the effect of the sixth embodiment described above can be enjoyed.

According to the above-described embodiment, the combustion exhaust gas can be washed with a cleaning liquid to reduce the amount of amine released into the atmosphere.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof. Further, as a matter of course, it is also possible to partially and appropriately combine these embodiments within the scope of the gist of the present invention.

For example, in the second embodiment to the fifth embodiment, the first collection space where the first cleaning unit 21 comes into gas-liquid contact with the decarboxylated combustion exhaust gas 3 while the first cleaning liquid 11 falls in a mist state. An example is shown which is configured to have a 21d and a first injector 21e that injects the first cleaning liquid 11 toward the first recovery space 21d. However, in the same manner as in the form shown in FIG. 7, the first cleaning unit 21 and the first recovery unit 21a for recovering the amine by contacting the decarboxylated combustion exhaust gas 3 with the decarboxylated combustion exhaust gas 3 while flowing the first cleaning liquid 11 on the surface. , The first cleaning liquid disperser 21b provided above the first recovery unit 21a may be provided. Even in this case, the effects of each embodiment can be enjoyed.

Further, in the second embodiment to the fifth embodiment, an example in which the first cleaning unit outlet demister 82 is provided between the first cleaning unit 21 and the second cleaning unit 22 is shown. However, the first cleaning unit outlet demister 82 may not be provided in the same manner as in the modes shown in FIGS. 7 and 9. Even in this case, the effects of each embodiment can be enjoyed.

1: Carbon dioxide recovery system, 2: Combustion exhaust gas, 3: Decarbonated combustion exhaust gas, 4: Rich liquid, 5: Lean liquid, 6: Heating medium, 8: Carbon dioxide-containing gas, 10: Carbon dioxide gas, 11: No. 1 cleaning liquid, 12: second cleaning liquid, 13: third cleaning liquid, 20: absorption tower, 20a: carbon dioxide recovery unit, 21: first cleaning unit, 21a: first recovery unit, 21b: first cleaning liquid disperser, 21c : 1st receiving part, 21d: 1st collecting space, 21e: 1st injector, 22: 2nd cleaning part, 22a: 2nd collecting part, 22b: 2nd cleaning liquid disperser, 22c: 2nd receiving part, 22d : 2nd recovery space, 22e: 2nd injector, 23: 3rd cleaning unit, 30: regeneration tower, 33: reboiler, 52: 1st heater, 53: 2nd heater, 61: 1st bypass line, 62: 2nd bypass line, 81: Recovery section outlet demister, 82: 1st cleaning section outlet demister, 83: 2nd cleaning section outlet demister, 84: 3rd cleaning section outlet demister

Claims (3)

A carbon dioxide recovery unit that absorbs carbon dioxide contained in combustion exhaust gas into an absorption liquid containing amine,
The first cleaning unit that recovers the amine accompanying the combustion exhaust gas by cleaning the combustion exhaust gas discharged from the carbon dioxide recovery unit with the first cleaning liquid, and the first cleaning unit.
A second cleaning unit that cleans the combustion exhaust gas discharged from the first cleaning unit with a second cleaning liquid and recovers the amine accompanying the combustion exhaust gas.
A third cleaning unit that cleans the combustion exhaust gas discharged from the second cleaning unit with a third cleaning liquid and recovers the amine accompanying the combustion exhaust gas.
A second cleaning unit outlet demister provided between the second cleaning unit and the third cleaning unit to capture the mist accompanying the combustion exhaust gas discharged from the second cleaning unit.
A third cleaning unit outlet demister that captures the mist accompanying the combustion exhaust gas discharged from the third cleaning unit is provided.
The third cleaning unit outlet demister is formed more sparsely than the second cleaning unit outlet demister .
The first cleaning unit includes an injector that injects the first cleaning liquid downward, a receiving unit that is provided below the injector and receives the first cleaning liquid injected from the injector, the injector, and the injection unit. It has a recovery space provided between the receiving portion and in contact with the combustion exhaust gas while the first cleaning liquid sprayed from the injector freely drops.
A carbon dioxide recovery system configured so that the first cleaning liquid that has passed through the recovery space is directly received by the receiving portion. Further provided is a recovery unit outlet demister provided between the carbon dioxide recovery unit and the first cleaning unit to capture mist accompanying the combustion exhaust gas discharged from the carbon dioxide recovery unit.
The carbon dioxide recovery system according to claim 1, wherein the recovery unit outlet demister is formed more sparsely than the second cleaning unit outlet demister. In the carbon dioxide recovery unit, the process of absorbing carbon dioxide contained in the combustion exhaust gas into the absorption liquid containing amine, and
A step of cleaning the combustion exhaust gas discharged from the carbon dioxide recovery unit with the first cleaning liquid in the first cleaning unit to recover the amine accompanying the combustion exhaust gas.
A step of cleaning the combustion exhaust gas discharged from the first cleaning unit with a second cleaning liquid in the second cleaning unit to recover the amine accompanying the combustion exhaust gas.
A step of capturing the mist accompanying the combustion exhaust gas discharged from the second cleaning unit with the second cleaning unit outlet demister, and
A step of cleaning the combustion exhaust gas discharged from the outlet demister of the second cleaning unit with a third cleaning liquid in the third cleaning unit to recover the amine accompanying the combustion exhaust gas.
A step of capturing the mist accompanying the combustion exhaust gas discharged from the third cleaning unit with the outlet demister of the third cleaning unit is provided.
The third cleaning unit outlet demister is formed more sparsely than the second cleaning unit outlet demister .
The first cleaning unit includes an injector that injects the first cleaning liquid downward, a receiving unit that is provided below the injector and receives the first cleaning liquid injected from the injector, the injector, and the injection unit. It has a recovery space provided between the receiving portion and in contact with the combustion exhaust gas while the first cleaning liquid sprayed from the injector freely drops.
A method for operating a carbon dioxide recovery system, wherein the first cleaning liquid that has passed through the recovery space is directly received by the receiving portion.

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