A system for recovering carbon dioxide from lime kiln flue gas

Abstract

The utility model discloses a system for recovering carbon dioxide in lime kiln flue gas, which comprises an enrichment collection pipeline, a secondary washing pipeline, a carbon dioxide recovery pipeline, a backwashing pipeline and a secondary absorption pipeline; the air inlet end of the enrichment collection pipeline is connected with the lime kiln flue gas exhaust pipe, and an enrichment collection pipeline air inlet valve group, a heat exchanger, a scrubber and a gas-liquid separator are arranged on the enrichment collection pipeline according to the air flow direction; the enrichment collection pipeline can preliminarily remove impurity particles in the lime kiln flue gas, so as to improve the recovery efficiency of subsequent carbon dioxide recovery operations, and the series-connected absorption tower I and absorption tower II further process the flue gas treated by the enrichment collection pipeline, and jointly recover the carbon dioxide in the flue gas. Compared with the previous parallel absorption tower group, the absorption of the series-connected absorption towers is more thorough and has better absorption efficiency.

Description

Technical Field

[0001] The utility model relates to the technical field of smelting, in particular to a system for recovering carbon dioxide in lime kiln flue gas. Background Art

[0002] Lime kilns produce flue gas containing carbon dioxide during the production process. In order to recover this carbon dioxide, the traditional method of the group is to use washing equipment to perform preliminary treatment on the flue gas. In this process, the washing equipment usually sprays liquid into the flue gas to dissolve some impurity particles in the flue gas in the liquid. The flue gas after washing will enter the gas-liquid separator for dehydration, so as to dry the flue gas before entering the absorption tower; however, in the actual operation process, the pipeline between the gas-liquid separator and the absorption tower is sometimes blocked. After analysis, it is found that this is because the particles carried in the flue gas or the incompletely separated liquid accumulate on the inner wall of the pipeline, resulting in a smaller inner diameter of the pipeline, thereby obstructing the flow of flue gas; in addition, when the carbon dioxide content in the flue gas is low, the absorption efficiency of the absorption tower will also be affected, resulting in a decrease in absorption efficiency; therefore, it is necessary to further improve the lime kiln flue gas treatment system in the factory area to improve the recovery efficiency and stability of carbon dioxide in the lime kiln flue gas. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a system for recovering carbon dioxide in lime kiln flue gas, which can avoid pipe blockage at the front of an absorption tower and effectively improve the efficiency of the absorption tower in recovering carbon dioxide in lime kiln flue gas.

[0004] The technical problem to be solved by the utility model is achieved through the following technical scheme: a system for recovering carbon dioxide from lime kiln flue gas, the system comprising an enrichment and collection pipeline, a secondary washing pipeline, a carbon dioxide recovery pipeline, a backwashing pipeline and a secondary absorption pipeline;

[0005] The air inlet end of the enrichment and collection pipeline is connected to the lime kiln smoke exhaust pipe, and an enrichment and collection pipeline air inlet valve group, a heat exchanger, a scrubber and a gas-liquid separator are arranged on the enrichment and collection pipeline according to the air flow direction;

[0006] The air inlet end of the secondary washing pipeline is connected to the enrichment collection pipeline between the scrubber and the gas-liquid separator through a secondary washing air inlet three-way valve, and the air outlet end is connected to the enrichment collection pipeline on the front side of the heat exchanger through a secondary washing air outlet three-way valve;

[0007] The air inlet end of the carbon dioxide recovery pipeline is connected to the air outlet end of the gas-liquid separator, and an absorption tower I, an absorption tower II, a regeneration tower and a storage tank are arranged in sequence on the carbon dioxide recovery pipeline according to the air flow direction. The air outlet end of the absorption tower I is connected to the air inlet end of the absorption tower II, and the absorption liquid discharge pipes of the absorption towers I and II are connected in parallel to the regeneration tower, and the waste liquid of the regeneration tower is connected to the liquid inlet of the storage tank;

[0008] The liquid inlet end of the backwash pipeline is connected to the absorbent liquid supply pipe in the absorption tower I, and the liquid outlet end of the backwash pipeline is connected to the enrichment collection pipeline between the gas-liquid separator and the gas inlet end of the absorption tower I through the backwash three-way valve, so as to backwash the pipeline between the gas-liquid separator and the absorption tower I;

[0009] The liquid inlet end of the secondary absorption pipeline is connected to the pipeline at the gas inlet end of the regeneration tower through a secondary absorption three-way valve, and the liquid outlet end is connected to the top of the absorption tower II.

[0010] Preferably, a common pipeline and a spare pipeline are arranged between the backwash three-way valve and the air inlet end of the absorption tower I, and the air inlet ends of the common pipeline and the spare pipeline are connected to the backwash three-way valve through the three-way valve, and the air outlet ends are connected to the air inlet end of the absorption tower I.

[0011] Preferably, the scrubber is a wet scrubber.

[0012] Preferably, a stop valve I is installed at the gas outlet end of the gas-liquid separator.

[0013] Preferably, a stop valve II is installed at the liquid inlet end of the backwash pipeline.

[0014] Preferably, a stop valve III is installed on the absorption liquid discharge pipe of the absorption tower I.

[0015] Preferably, a stop valve IV is installed on the gas outlet end of the absorption tower I.

[0016] Compared with the prior art, the beneficial technical effects of the utility model are:

[0017] (1) The enrichment and collection pipeline can be used to preliminarily remove impurity particles in the lime kiln flue gas, thereby improving the recovery efficiency of the subsequent carbon dioxide recovery operation. The series-connected absorption tower I and absorption tower II further treat the flue gas after being treated by the enrichment and collection pipeline, and jointly recover the carbon dioxide in the flue gas. Compared with the previous parallel absorption tower group, the absorption of the series-connected absorption tower is more thorough and has better absorption efficiency;

[0018] (2) The secondary washing pipeline can circulate the lime kiln flue gas entering the enrichment collection pipeline, so that the flue gas is repeatedly washed by the scrubber, minimizing the solid content of the flue gas and avoiding the problem of subsequent pipeline blockage;

[0019] (3) Since the inner wall of the pipeline between the gas-liquid separator and the absorption tower I is easily attached with solid impurities in the flue gas, the backwash pipeline can be set to backwash the pipeline between the gas-liquid separator and the absorption tower I to prevent the pipeline from being blocked;

[0020] (4) The secondary absorption pipeline can circulate and absorb the flue gas entering the absorption tower II, thereby strengthening the absorption treatment of the flue gas by the absorption tower II. Its structural design is reasonable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the utility model.

[0022] In the figure: 1. Enrichment and collection pipeline; 2. Secondary washing pipeline; 3. Carbon dioxide recovery pipeline; 4. Backwashing pipeline; 5. Secondary absorption pipeline; 6. Enrichment and collection pipeline inlet valve group; 7. Heat exchanger; 8. Scrubber; 9. Gas-liquid separator; 10. Stop valve I; 11. Secondary washing inlet three-way valve; 12. Secondary washing outlet three-way valve; 13. Absorption tower I; 14. Absorption tower II; 15. Regeneration tower; 16. Storage tank; 17. Stop valve III; 18. Stop valve II; 19. Common pipeline; 20. Spare pipeline; 21. Backwashing three-way valve; 22. Secondary absorption three-way valve. DETAILED DESCRIPTION

[0023] The specific technical solutions of the present invention are further described below with reference to the accompanying drawings, so as to facilitate further understanding of the present invention by those skilled in the art, and do not constitute any limitation to the rights thereof.

[0024] Example 1, reference Figure 1 A system for recovering carbon dioxide from lime kiln flue gas, the system comprising an enrichment collection pipeline 1, a secondary washing pipeline 2, a carbon dioxide recovery pipeline 3, a backwash pipeline 4 and a secondary absorption pipeline 5. The enrichment collection pipeline 1 can preliminarily remove impurity particles in the lime kiln flue gas, thereby improving the recovery efficiency of subsequent carbon dioxide recovery operations. The series-connected absorption towers I and II further process the flue gas treated by the enrichment collection pipeline 1, and jointly recover carbon dioxide from the flue gas. Compared with the previous parallel absorption tower group, the absorption of the series-connected absorption towers is more thorough and has better absorption efficiency;

[0025] The air inlet end of the enrichment and collection pipeline 1 is connected to the lime kiln flue gas exhaust pipe. The enrichment and collection pipeline air inlet valve group 6, heat exchanger 7, scrubber 8 and gas-liquid separator 9 are arranged on the enrichment and collection pipeline 1 according to the air flow direction. The enrichment and collection pipeline air inlet valve group 6 includes a valve, a flow meter and a pump body. The scrubber 8 is a wet scrubber. The gas outlet end of the gas-liquid separator 9 is equipped with a stop valve I10;

[0026] The air inlet end of the secondary washing pipeline 2 is connected to the enrichment collection pipeline 1 between the scrubber 8 and the gas-liquid separator 9 through the secondary washing air inlet three-way valve 11, and the air outlet end is connected to the enrichment collection pipeline 1 on the front side of the heat exchanger 7 through the secondary washing air outlet three-way valve 12. The secondary washing pipeline 2 can circulate the lime kiln flue gas entering the enrichment collection pipeline 1, so that the flue gas is repeatedly washed by the scrubber 8, thereby minimizing the solid content of the flue gas and avoiding the problem of subsequent pipeline blockage;

[0027] The air inlet end of the carbon dioxide recovery pipeline 3 is connected to the air outlet end of the gas-liquid separator 9, and an absorption tower Ⅰ13, an absorption tower Ⅱ14, a regeneration tower 15 and a storage tank 16 are sequentially arranged on the carbon dioxide recovery pipeline 3 according to the air flow direction, the air outlet end of the absorption tower Ⅰ13 is connected to the air inlet end of the absorption tower Ⅱ14, a stop valve Ⅲ17 is installed on the absorption liquid discharge pipe of the absorption tower Ⅰ13, and a stop valve Ⅳ is installed on the air outlet end of the absorption tower Ⅰ13. The absorption liquid discharge pipes of the absorption tower Ⅰ13 and the absorption tower Ⅱ14 are connected in parallel to the regeneration tower 15, and the waste liquid of the regeneration tower 15 is connected to the liquid inlet of the storage tank 16, and the storage tank 16 stores the waste liquid discharged from the regeneration tower 15;

[0028] The liquid inlet end of the backwash pipeline 4 is connected to the absorbent liquid supply pipe (not shown) in the absorption tower Ⅰ13. A stop valve Ⅱ18 is installed at the liquid inlet end of the backwash pipeline 4. The liquid outlet end of the backwash pipeline 4 is connected to the enrichment collection pipeline 1 between the gas-liquid separator 9 and the gas inlet end of the absorption tower Ⅰ13 through the backwash three-way valve 21, so as to backwash the pipeline between the gas-liquid separator 9 and the absorption tower Ⅰ13. Because the inner wall of the pipeline between the gas-liquid separator 9 and the absorption tower Ⅰ13 is easily attached with solid impurities in the flue gas, the backwash pipeline 4 can be set to backwash the pipeline between the gas-liquid separator 9 and the absorption tower Ⅰ13, so as to prevent the pipeline from being blocked;

[0029] A common pipeline 19 and a spare pipeline 20 are arranged between the backwash three-way valve 21 and the air inlet end of the absorption tower Ⅰ13. Both the common pipeline 19 and the spare pipeline 20 can be flushed by the backwash pipeline 4. The air inlet ends of the common pipeline 19 and the spare pipeline 20 are connected to the backwash three-way valve 21 through the three-way valve, and the air outlet ends are connected to the air inlet end of the absorption tower Ⅰ13.

[0030] The liquid inlet end of the secondary absorption pipeline 5 is connected to the pipeline at the air inlet end of the regeneration tower 15 through the secondary absorption three-way valve 22, and the liquid outlet end is connected to the top of the absorption tower II 14. The secondary absorption pipeline 5 can circulate and absorb the flue gas entering the absorption tower II 14, thereby strengthening the absorption treatment of the flue gas by the absorption tower II 14.

[0031] When the carbon dioxide recovery system in lime kiln flue gas is used: the lime kiln flue gas is heat exchanged in the heat exchanger 7 and then enters the wet scrubber 8 for washing to reduce the solid content of the flue gas. After washing, the flue gas enters the absorption tower I 13 and the absorption tower II 14 through the gas-liquid separator 9. The flue gas is absorbed by the absorption tower I 13 and the absorption tower II 14 in sequence and then enters the regeneration tower 15. The regeneration tower 15 heats the absorption liquid to release the carbon dioxide, which is then discharged from the gas outlet of the regeneration tower 15. The waste liquid in the regeneration tower 15 enters the storage tank 16 for storage.

[0032] When the secondary washing pipeline 2 is opened: when the solid content of the lime kiln flue gas is high, the secondary washing outlet three-way valve 12 is used to keep the outlet end of the secondary washing pipeline 2 connected to the enrichment collection pipeline 1, and the secondary washing inlet three-way valve 11 is used to keep the inlet end of the secondary washing pipeline 2 connected to the pipeline between the scrubber 8 and the gas-liquid separator 9, so that the scrubber 8 repeatedly washes the flue gas, thereby reducing the solid content of the flue gas;

[0033] When the backwash pipeline 4 is opened: when the air flow velocity of the pipeline between the gas-liquid separator 9 and the absorption tower Ⅰ13 is low, it is determined that the pipeline has been blocked to varying degrees. At this time, the liquid outlet of the backwash pipeline 4 is connected to the pipeline on the air inlet end of the absorption tower Ⅰ13 through the backwash three-way valve 21, so that the absorption liquid in the absorption material supply pipe in the absorption tower Ⅰ13 can be used to wash the pipeline between the gas-liquid separator 9 and the absorption tower Ⅰ13 through the backwash pipe, and the impurity particles attached to the inner peripheral surface of the pipeline are washed away to a certain extent;

[0034] When the secondary absorption pipeline 5 is opened: when the amount of carbon dioxide gas recovery is low, the secondary absorption three-way valve 22 is used to keep the liquid inlet end of the secondary absorption pipeline 5 connected with the absorption liquid discharge pipes of absorption tower Ⅰ13 and absorption tower Ⅱ14, so that the absorption liquid in the absorption liquid discharge pipes of absorption liquid Ⅰ and absorption liquid Ⅱ no longer flows into the regeneration tower 15, but flows into the absorption tower Ⅱ14, so that the absorption liquid in the absorption tower Ⅱ14 absorbs the flue gas again. The opening duration of the secondary absorption pipeline 5 can be selected according to the use requirements. When the secondary absorption pipeline 5 is no longer opened, the regeneration tower 15 can be restored to regenerate the absorption liquid of absorption tower Ⅰ13 and absorption tower Ⅱ14, thereby enhancing the absorption rate of carbon dioxide in the lime kiln flue gas to a certain extent.

Claims

1. A system for recovering carbon dioxide from lime kiln flue gas, characterized in that: The system includes an enrichment collection pipeline, a secondary washing pipeline, a carbon dioxide recovery pipeline, a backwash pipeline and a secondary absorption pipeline; The air inlet end of the enrichment and collection pipeline is connected to the lime kiln smoke exhaust pipe, and an enrichment and collection pipeline air inlet valve group, a heat exchanger, a scrubber and a gas-liquid separator are arranged on the enrichment and collection pipeline according to the air flow direction; The air inlet end of the secondary washing pipeline is connected to the enrichment collection pipeline between the scrubber and the gas-liquid separator through a secondary washing air inlet three-way valve, and the air outlet end is connected to the enrichment collection pipeline on the front side of the heat exchanger through a secondary washing air outlet three-way valve; The air inlet end of the carbon dioxide recovery pipeline is connected to the air outlet end of the gas-liquid separator, and an absorption tower I, an absorption tower II, a regeneration tower and a storage tank are arranged in sequence on the carbon dioxide recovery pipeline according to the air flow direction. The air outlet end of the absorption tower I is connected to the air inlet end of the absorption tower II, and the absorption liquid discharge pipes of the absorption towers I and II are connected in parallel to the regeneration tower, and the waste liquid of the regeneration tower is connected to the liquid inlet of the storage tank; The liquid inlet end of the backwash pipeline is connected to the absorbent liquid supply pipe in the absorption tower I, and the liquid outlet end of the backwash pipeline is connected to the enrichment collection pipeline between the gas-liquid separator and the gas inlet end of the absorption tower I through the backwash three-way valve, so as to backwash the pipeline between the gas-liquid separator and the absorption tower I; The liquid inlet end of the secondary absorption pipeline is connected to the pipeline at the gas inlet end of the regeneration tower through a secondary absorption three-way valve, and the liquid outlet end is connected to the top of the absorption tower II.

2. A system for recovering carbon dioxide from lime kiln flue gas according to claim 1, characterized in that: A common pipeline and a spare pipeline are arranged between the backwash three-way valve and the air inlet end of the absorption tower I. The air inlet ends of the common pipeline and the spare pipeline are connected to the backwash three-way valve through the three-way valve, and the air outlet ends are connected to the air inlet end of the absorption tower I.

3. The system for recovering carbon dioxide from lime kiln flue gas according to claim 1, characterized in that: The scrubber is a wet scrubber.

4. The system for recovering carbon dioxide from lime kiln flue gas according to claim 1, characterized in that: A stop valve I is installed at the gas outlet end of the gas-liquid separator.

5. The system for recovering carbon dioxide from lime kiln flue gas according to claim 1, characterized in that: A stop valve II is installed at the liquid inlet end of the backwash pipeline.

6. The system for recovering carbon dioxide from lime kiln flue gas according to claim 1, characterized in that: A stop valve III is installed on the absorption liquid discharge pipe of the absorption tower I.

7. The system for recovering carbon dioxide from lime kiln flue gas according to claim 1, characterized in that: A stop valve IV is installed on the gas outlet end of the absorption tower I.

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