A carbon dioxide capture waste heat flash regeneration system

Abstract

The present invention provides a carbon dioxide capture waste heat flash regeneration system, which belongs to the technical field of carbon dioxide capture, and comprises: an absorption tower, a regeneration tower and a reboiler, wherein the absorption tower is provided with a self-circulation pipeline, one end of the self-circulation pipeline leads to the absorption liquid at the bottom of the absorption tower, and the other end of the self-circulation pipeline leads to the inner cavity of the top of the absorption tower, and the self-circulation pipeline is connected with a flash tank before entering the inner cavity of the top of the absorption tower; the rear end of the rough gas exhaust port of the regeneration tower is connected with a first cooling heat exchanger, and the first cooling heat exchanger is connected with the flash tank; the carbon dioxide capture waste heat flash regeneration system of the present invention is connected with a first cooling heat exchanger at the rear end of the rough gas exhaust port of the regeneration tower, and the first cooling heat exchanger can be used to heat the absorption liquid in the self-circulation pipe, thereby recovering the exhaust waste heat of the regeneration tower, and the heated self-circulation absorbent flashes in the flash tank to realize partial regeneration of the absorbent, thereby achieving the purpose of energy saving.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture, and in particular to a carbon dioxide capture waste heat flash regeneration system. Background Art

[0002] CCS technology is the abbreviation of Carbon Capture and Storage, which is a technology for capturing and storing carbon dioxide (CO2). CCS technology refers to separating carbon dioxide produced by industry and related energy industries through carbon capture technology, and then transporting and storing it to the seabed or underground, etc., isolated from the atmosphere, through carbon storage methods.

[0003] CCS technology consists of two parts: carbon capture and carbon storage. Among them, carbon capture technology was first applied in the oil refining and chemical industries. Since the CO2 emitted by these industries is of high concentration and high pressure, the capture cost is not high. However, the CO2 emitted by coal-fired power plants is just the opposite. Capturing carbon dioxide from power plant emissions has the problem of high energy consumption and cost.

[0004] The energy consumption of the carbon dioxide capture system is mainly the regeneration steam consumption of the regeneration tower. Since the temperature difference between the lean liquid at the bottom of the regeneration tower and the regeneration gas at the top of the tower is not much, the heat they contain is also relatively close. If the heat is recovered by the rich liquid at the bottom of the absorption tower, only the heat of the lean liquid at the bottom of the tower or the top of the tower can be recovered. The temperature of the heated rich liquid is not much different from the temperature of the remaining other logistics, and the heat contained in the other logistics cannot be recovered. At present, the other logistics can only be cooled by circulating cooling water, resulting in almost half of the heat being wasted. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of excessively high energy consumption of the carbon dioxide capture system used in power plants in the prior art, thereby providing a carbon dioxide capture waste heat flash regeneration system.

[0006] In order to solve the above technical problems, the present invention provides a carbon dioxide capture waste heat flash regeneration system, comprising:

[0007] An absorption tower, one end of which is connected to the flue gas outlet of the power plant, and the interior of which is suitable for containing absorption liquid. The absorption liquid in the absorption tower absorbs carbon dioxide in the flue gas and becomes rich liquid; the absorption tower is provided with a self-circulating pipeline, one end of which leads to the absorption liquid at the bottom of the absorption tower, and the other end of which leads to the inner cavity at the top of the absorption tower, and the self-circulating pipeline is connected to a flash tank before entering the inner cavity at the top of the absorption tower;

[0008] A regeneration tower is connected to the rich liquid in the absorption tower through a pipeline, the regeneration tower is provided with a crude gas exhaust port, the rear end of the crude gas exhaust port of the regeneration tower is connected to a first cooling heat exchanger, the cooling water inlet of the first cooling heat exchanger is connected to the pipe section of the self-circulating pipeline of the absorption tower leading to the absorption liquid at the bottom of the tower, and the cooling water outlet of the first cooling heat exchanger is connected to a flash tank on the self-circulating pipeline of the absorption tower;

[0009] The reboiler is connected to the regeneration tower and is used to vaporize the rich liquid entering the regeneration tower into gas-liquid two-phases, wherein the liquid phase becomes the lean liquid and the gas phase is discharged from the raw gas exhaust port of the regeneration tower.

[0010] Optionally, the self-circulating pipeline of the absorption tower is provided with a self-circulating heat exchanger before it leads to the inner cavity at the top of the absorption tower and after the flash tank.

[0011] Optionally, a spray device is provided on the outlet of one end of the self-circulating pipeline leading to the inner cavity at the top of the absorption tower.

[0012] Optionally, the absorption tower is provided with a tail gas exhaust port, a tail gas heat exchanger is provided at the front end of the tail gas exhaust port, and the tail gas heat exchanger is arranged above the self-circulation pipeline.

[0013] Optionally, a demister is further provided at the front end of the tail gas exhaust port of the absorption tower.

[0014] Optionally, a demister is provided at the front end of the rough gas exhaust port of the regeneration tower.

[0015] Optionally, the raw gas exhaust port of the regeneration tower is communicated with a gas-liquid separator, and the separated water of the gas-liquid separator flows back into the regeneration tower.

[0016] Optionally, it further comprises: a reflux liquid storage tank, wherein the separated water discharged from the gas-liquid separator first enters the reflux liquid storage tank and then refluxes into the regeneration tower.

[0017] Optionally, the flash tank is provided with a flash gas exhaust port, and the flash gas exhaust port is communicated with a gas-liquid separator.

[0018] Optionally, a second cooling heat exchanger is further provided at the rear end of the first cooling heat exchanger, and the flash gas exhaust port of the flash tank enters the gas-liquid separator after passing through the second cooling heat exchanger.

[0019] The technical solution of the present invention has the following advantages:

[0020] 1. The carbon dioxide capture waste heat flash regeneration system provided by the present invention is connected to a first cooling heat exchanger at the rear end of the raw gas exhaust port of the regeneration tower. The first cooling heat exchanger is connected to the self-circulation pipeline of the absorption tower and is used to heat the absorption liquid in the self-circulation pipe, thereby recovering the exhaust waste heat of the regeneration tower. The heated self-circulation absorbent flashes in the flash tank to achieve partial regeneration of the absorbent. Under the condition of a certain regeneration amount, the regeneration degree of the rich liquid sent to the regeneration tower can be reduced, thereby achieving the purpose of energy saving.

[0021] 2. The carbon dioxide capture waste heat flash regeneration system provided by the present invention heats the absorption liquid in the absorption tower through the first cooling heat exchanger, and then the absorption liquid enters the flash tank to desorb part of the carbon dioxide, thereby improving the efficiency of the absorption tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a schematic diagram of a carbon dioxide capture waste heat flash regeneration system provided in an embodiment of the present invention.

[0024] Description of reference numerals:

[0025] 1. Flash tank; 2. Absorption tower; 3. Regeneration tower; 4. Reboiler; 5. Gas-liquid separator; 6. Crude gas exhaust port; 7. First cooling heat exchanger; 8. Rich liquid supply pipe; 9. Lean liquid return pipe; 10. Lean-rich liquid heat exchanger; 11. Lean liquid heat exchanger; 12. Tail gas exhaust port; 13. Tail gas heat exchanger; 14. Reflux liquid storage tank; 15. Flash gas exhaust port; 16. Second cooling heat exchanger. DETAILED DESCRIPTION

[0026] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] This embodiment provides a carbon dioxide capture waste heat flash regeneration system, such as Figure 1 As shown, it includes: a carbon dioxide capture system and a waste heat flash regeneration system, wherein the waste heat flash regeneration system includes a flash tank 1, and the flash tank 1 recovers waste heat from the regeneration gas discharged from the regeneration tower 3 of the carbon dioxide capture system, and uses the waste heat to partially flash the absorption liquid in the absorption tower 2 of the carbon dioxide capture system, so that the carbon dioxide gas in the absorption liquid is partially separated out in advance, reducing the steam consumption of the reboiler 4, thereby reducing the system's consumption of turbine extraction steam as a whole.

[0031] like Figure 1 As shown, the carbon dioxide capture system includes: an absorption tower 2, a regeneration tower 3, a reboiler 4 and a gas-liquid separator 5. One end of the absorption tower 2 is used to communicate with the flue gas outlet of the power plant, and the interior of the absorption tower 2 is suitable for accommodating absorption liquid. The absorption liquid in the absorption tower 2 absorbs carbon dioxide in the flue gas and becomes rich liquid; the absorption tower 2 is provided with a self-circulating pipeline, one end of which leads to the absorption liquid at the bottom of the absorption tower 2, and the other end of which leads to the inner cavity at the top of the absorption tower 2. The self-circulating pipeline is provided with a self-circulating pump, which is used to force the absorption liquid at the bottom of the absorption tower 2 to be sucked to the upper or middle part of the absorption tower 2, and the absorption liquid is evenly dispersed in the absorption tower 2 in a spraying manner, thereby improving the absorption effect of the absorption liquid on carbon dioxide in the flue gas.

[0032] like Figure 1 As shown, the regeneration tower 3 is connected to the rich liquid in the absorption tower 2 through a pipeline, and the regeneration tower 3 has a crude gas exhaust port 6. The rear end of the crude gas exhaust port 6 of the regeneration tower 3 is connected to a first cooling heat exchanger 7. The first cooling heat exchanger 7 is used to reduce the temperature of the regeneration gas discharged from the crude gas exhaust port 6, so as to facilitate the recovery of the waste heat of the regeneration gas. The regeneration tower 3 is connected to a reboiler 4, and the reboiler 4 is used to vaporize the rich liquid entering the regeneration tower 3 into gas-liquid two-phases, wherein the liquid phase becomes a lean liquid, and the gas phase is discharged from the crude gas exhaust port 6 of the regeneration tower 3. The heating steam of the reboiler 4 is extracted from the steam turbine, and the steam turbine extraction is used to heat the absorption liquid containing carbon dioxide, so as to precipitate the carbon dioxide gas.

[0033] like Figure 1 As shown, the regeneration tower 3 is connected to the rich liquid in the absorption tower 2 through a rich liquid supply pipe 8, one end of the rich liquid supply pipe 8 extends from the bottom of the absorption tower 2 into the absorption tower 2, and the other end of the rich liquid supply pipe 8 extends from the top of the regeneration tower 3 into the regeneration tower 3, and the rich liquid enters the top of the regeneration tower 3 from the absorption tower 2, and sprays downward from the inside of the top of the regeneration tower 3 by spraying, so as to precipitate the carbon dioxide gas contained in the rich liquid. In addition, a lean liquid return pipe 9 is also connected between the regeneration tower 3 and the absorption tower 2, one end of the lean liquid return pipe 9 is connected to the inside of the bottom end of the regeneration tower 3, and the other end of the lean liquid return pipe 9 is connected to the inside of the top of the absorption tower 2, and sprays in the top of the absorption tower 2 by spraying. The lean liquid return pipe 9 and the rich liquid supply pipe 8 are connected via a lean-rich liquid heat exchanger 10, that is, after the hotter lean liquid in the lean liquid return pipe 9 transfers heat to the rich liquid in the rich liquid supply pipe 8 through the lean-rich liquid heat exchanger 10, the lean liquid in the lean liquid return pipe 9 is returned to the absorption tower 2, thereby recovering the heat of the lean liquid in the regeneration tower 3. A lean liquid heat exchanger 11 is also provided on the lean liquid return pipe 9, through which the lean liquid heat exchanger 11 cools the lean liquid and restores the absorption of carbon dioxide in the flue gas by the absorption liquid.

[0034] like Figure 1As shown, the self-circulating pipe on the absorption tower 2 extends from the bottom of the absorption tower 2, and then the self-circulating pipe leads to the first cooling heat exchanger 7 at the top of the regeneration tower 3. The absorption liquid drawn from the bottom of the absorption tower 2 by the self-circulating pipe is used as the cooling water of the first cooling heat exchanger 7, and the cooling water outlet of the first cooling heat exchanger 7 is connected to the flash tank 1, and then the bottom of the flash tank 1 is connected to the inner cavity of the top of the absorption tower 2, so as to return the absorption liquid to the absorption tower 2. Through the flash tank 1, part of the carbon dioxide in the absorption liquid is flashed out, so as to be recovered in advance, so as to restore the absorption capacity of the absorption liquid and increase the efficiency of the absorption tower 2.

[0035] like Figure 1 As shown, a spray device is provided at the outlet of one end of the self-circulating pipeline leading to the inner cavity at the top of the absorption tower 2, through which the absorption liquid is evenly distributed in the absorption tower 2, so as to facilitate the absorption of carbon dioxide in the flue gas by the absorption liquid.

[0036] like Figure 1 As shown, the absorption tower 2 has a tail gas discharge port 12, and the front end of the tail gas discharge port 12 has a tail gas heat exchanger 13, and the tail gas heat exchanger 13 is arranged above the self-circulation pipeline. The front end of the tail gas discharge port 12 of the absorption tower 2 also has a demister, which is arranged between the tail gas heat exchanger 13 and the tail gas discharge port 12, and is used to demist the discharged flue gas to reduce the water content in the flue gas. Specifically, the tail gas heat exchanger 13 is a wide channel plate heat exchanger, through which the escape rate of the absorbent from the top of the absorption tower 2 can be reduced. The wide channel plate heat exchanger has the advantages of small heat exchange end difference and large heat exchange coefficient. The cooling circulating water exchanges heat with the flue gas through the inter-wall heat exchange. The flue gas temperature at the top of the absorption tower 2 is saturated flue gas. After heat exchange with the cooling circulating water, water is precipitated, and the absorption liquid carried in the flue gas is also precipitated. The precipitated water and absorbent flow back to the absorption tower 2 along the heat exchange wall of the plate heat exchanger for reuse. In addition, the absorption tower 2 is also provided with a demister between the exhaust gas heat exchanger 13 and the exhaust gas exhaust port 12, which is used to reduce the water content in the flue gas.

[0037] like Figure 1 As shown, a demister is provided at the front end of the crude gas outlet 6 of the regeneration tower 3, and the demister is used to reduce the water content of the discharged regeneration gas. The crude gas outlet 6 of the regeneration tower 3 is connected to the gas-liquid separator 5, and the separated water of the gas-liquid separator 5 flows back into the regeneration tower 3. Specifically, it also includes: a reflux liquid storage tank 14, and the separated water discharged from the gas-liquid separator 5 first enters the reflux liquid storage tank 14, and then flows back into the regeneration tower 3.

[0038] like Figure 1As shown, the flash tank 1 is provided with a flash gas exhaust port 15, and the flash gas exhaust port 15 is connected to the gas-liquid separator 5, so as to separate the carbon dioxide gas flashed from the flash tank 1 into steam and water. Preferably, a second cooling heat exchanger 16 is further provided at the rear end of the first cooling heat exchanger 7, and the flash gas exhaust port 15 of the flash tank 1 enters the gas-liquid separator 5 after passing through the second cooling heat exchanger 16, and the second cooling heat exchanger 16 is used to further cool the carbon dioxide gas to recover the waste heat and facilitate the subsequent steam-water separation.

[0039] Obviously, the above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the present invention.

Claims

1. A carbon dioxide capture waste heat flash regeneration system, characterized in that: include: An absorption tower (2) has one end connected to the flue gas outlet of the power plant, and the interior is suitable for containing absorption liquid, and the absorption liquid in the absorption tower (2) becomes rich liquid after absorbing carbon dioxide in the flue gas; the absorption tower (2) has a self-circulating pipeline, one end of the self-circulating pipeline leads to the absorption liquid at the bottom of the absorption tower (2), and the other end of the self-circulating pipeline leads to the top inner cavity of the absorption tower (2), and the self-circulating pipeline is connected to a flash tank (1) before entering the top inner cavity of the absorption tower (2); The regeneration tower (3) is connected to the rich liquid in the absorption tower (2) through a pipeline, the regeneration tower (3) is provided with a coarse gas exhaust port (6), the rear end of the coarse gas exhaust port (6) of the regeneration tower (3) is connected to a first cooling heat exchanger (7), the cooling water inlet of the first cooling heat exchanger (7) is connected to the pipe section of the self-circulating pipeline of the absorption tower (2) leading to the absorption liquid at the bottom of the tower, and the cooling water outlet of the first cooling heat exchanger (7) is connected to the flash tank (1) on the self-circulating pipeline of the absorption tower (2); A reboiler (4) is connected to the regeneration tower (3) and is used to vaporize the rich liquid entering the regeneration tower (3) into gas-liquid two-phases, wherein the liquid phase becomes lean liquid and the gas phase is discharged from the raw gas exhaust port (6) of the regeneration tower (3); The self-circulating pipeline of the absorption tower (2) is provided with a self-circulating heat exchanger before it leads to the inner cavity at the top of the absorption tower (2) and after the flash tank (1); a spray device is provided at the outlet of one end of the self-circulating pipeline leading to the inner cavity at the top of the absorption tower (2).

2. The carbon dioxide capture waste heat flash regeneration system according to claim 1, characterized in that: The absorption tower (2) is provided with a tail gas exhaust port (12), and a tail gas heat exchanger (13) is provided at the front end of the tail gas exhaust port (12). The tail gas heat exchanger (13) is arranged above the self-circulating pipeline.

3. The carbon dioxide capture waste heat flash regeneration system according to claim 2, characterized in that: The front end of the tail gas exhaust port (12) of the absorption tower (2) is also provided with a demister.

4. The carbon dioxide capture waste heat flash regeneration system according to claim 1, characterized in that: A demister is provided at the front end of the rough gas exhaust port (6) of the regeneration tower (3).

5. The carbon dioxide capture waste heat flash regeneration system according to claim 1, characterized in that: The raw gas exhaust port (6) of the regeneration tower (3) is in communication with the gas-liquid separator (5), and the separated water of the gas-liquid separator (5) flows back into the regeneration tower (3).

6. The carbon dioxide capture waste heat flash regeneration system according to claim 5, characterized in that: Also includes: A reflux liquid storage tank (14), wherein the separated water discharged from the gas-liquid separator (5) first enters the reflux liquid storage tank (14), and then refluxes into the regeneration tower (3).

7. The carbon dioxide capture waste heat flash regeneration system according to any one of claims 1 to 6, characterized in that: The flash tank (1) is provided with a flash gas exhaust port (15), and the flash gas exhaust port (15) is in communication with the gas-liquid separator (5).

8. The carbon dioxide capture waste heat flash regeneration system according to claim 7, characterized in that: A second cooling heat exchanger (16) is also provided at the rear end of the first cooling heat exchanger (7), and the flash gas exhaust port (15) of the flash tank (1) enters the gas-liquid separator (5) after passing through the second cooling heat exchanger (16).

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