Five-stage water absorption tower for treating methylamine exhaust gas system

Abstract

The utility model relates to methylamine waste gas treatment technical field, proposes a kind of five-stage water absorption tower processing methylamine waste gas system, the present design includes five-stage absorption tower, air draught fan and absorption liquid circulating system by pipeline in turn series connection. Waste gas enters from first stage absorption tower bottom, and countercurrent contact with absorption liquid from top to bottom spraying, after multistage purification by air draught fan from fifth stage tower top discharge. Absorption liquid circulating system includes the liquid seal groove of each stage tower, circulating pump, plate heat exchanger and spraying device, realize independent temperature control circulation. System uses countercurrent overflow design, fresh water is supplemented from fifth stage, and concentrated methylamine aqueous solution is guided from first stage to concentrated amine water storage tank and is recycled for production, realizes resource recycling. The utility model is through multistage purification, cascade cooling and on-line monitoring, effectively solve the methylamine waste gas treatment efficiency low, emission substandard and resource waste problem, with the advantages of high purification efficiency, stable operation, energy saving and environmental protection.

Description

Technical Field

[0001] This utility model relates to the field of methylamine waste gas treatment technology, specifically, to a five-stage water absorption tower system for treating methylamine waste gas. Background Technology

[0002] In the chemical production field, especially in processes involving creatine monohydrate, pesticides, and rubber accelerators, methylamine is frequently used as a key raw material. During the amination and hydrolysis reactions in these processes, large quantities of methylamine-containing waste gas are generated. Methylamine has a strong fishy odor and is highly irritating to the eyes and respiratory tract; direct emission poses serious harm to the environment and human health, therefore effective treatment is essential before discharge. Currently, water absorption is commonly used to treat methylamine waste gas, which is highly water-soluble. Traditional treatment devices often employ single- or two-stage absorption towers, which suffer from low absorption efficiency, substandard emissions, and high water consumption. For high-concentration or high-flow-rate methylamine waste gas, simple water absorption towers cannot guarantee stable treatment results. Furthermore, directly treating the saturated methylamine aqueous solution as wastewater not only increases the load on subsequent wastewater treatment but also wastes methylamine resources. Therefore, there is an urgent need for a highly efficient, stable, and resource-recoverable methylamine waste gas treatment system. Utility Model Content

[0003] This invention proposes a five-stage water absorption tower system for treating methylamine waste gas. The aim is to provide a multi-stage series, counter-current operation system that combines deep purification and raw material recovery functions to solve the problems of low absorption efficiency, excessive tail gas emissions, and failure to achieve resource recovery in the existing technology for methylamine waste gas.

[0004] The technical solution of this utility model is as follows: a five-stage water absorption tower system for treating methylamine waste gas, comprising a first-stage absorption tower, a second-stage absorption tower, a third-stage absorption tower, a fourth-stage absorption tower and a fifth-stage absorption tower connected in series by pipelines, as well as an induced draft fan, a tail gas emission pipe and an absorption liquid circulation system; The bottom of the first-stage absorption tower is equipped with a waste gas inlet for receiving methylamine-containing waste gas from the production workshop; The top of the fifth-stage absorption tower is equipped with a purified gas outlet, which is connected to the exhaust gas pipe via an induced draft fan. The absorbent circulation system includes a liquid seal tank, a circulation pump, a plate heat exchanger, and a spray device located at the bottom of each absorption tower. The spraying device is installed at the top inside each level of the absorption tower and is connected to the liquid seal tank at the bottom of the corresponding tower through a circulating pump to form an independent closed-loop circulation. The plate heat exchanger is connected in series in the pipeline between the outlet of the circulating pump and the spraying device to control the temperature of the absorbent liquid.

[0005] Preferably, the first-stage absorption tower and the fifth-stage absorption tower adopt an empty tower spray structure, and the tower is filled with Pall ring packing.

[0006] Preferably, the second-stage absorption tower, the third-stage absorption tower, and the fourth-stage absorption tower are all packed towers, and their interiors are filled with highly efficient structured packing.

[0007] Preferably, the liquid seal tank of the first-stage absorption tower is connected to the liquid seal tank of the second-stage absorption tower through a primary overflow pipe, and the liquid seal tank of the second-stage absorption tower is connected to the liquid seal tank of the third-stage absorption tower through a secondary overflow pipe, and so on, until the fourth-stage overflow pipe connects the liquid seal tank of the fourth-stage absorption tower to the liquid seal tank of the fifth-stage absorption tower, forming a countercurrent overflow path for the absorbent liquid.

[0008] Preferably, it also includes a concentrated amine water storage tank and a water replenishment pipeline; the inlet of the concentrated amine water storage tank is connected to the bottom of the liquid seal tank of the first-stage absorption tower through a discharge pump and pipeline. The water supply pipeline is connected to the liquid seal tank of the fifth-stage absorption tower and is used to replenish fresh process water into the system.

[0009] Preferably, the liquid seal tank of the first-stage absorption tower is equipped with an online density meter to monitor the concentration of methylamine in the absorption liquid and to control the start and stop of the discharge pump.

[0010] Preferably, the plate heat exchanger has a chilled water supply pipe connected to the refrigerant inlet and a chilled water return pipe connected to the refrigerant outlet, which is used to provide a low-temperature cold source for the absorbent.

[0011] Preferably, an online methylamine concentration monitor is installed on the exhaust pipe.

[0012] Preferably, glass rotor flowmeters and regulating valves are installed on the outlet pipes of the circulating pumps of each stage of the absorption tower.

[0013] Preferably, the overall frame, tower body and pipeline of the system are made of 316L stainless steel or fiberglass.

[0014] The beneficial effects of this utility model are as follows: I. High treatment efficiency and stable emissions meeting standards: A five-stage tower series design, combined with an optimized configuration of "pre-stage empty tower + intermediate packed tower + final empty tower," constructs a highly efficient multi-stage purification gradient. The waste gas and absorbent liquid come into counter-current contact, resulting in a large mass transfer driving force and thorough purification. The tail gas is finally washed with fresh water in the fifth-stage absorber, ensuring that the methylamine concentration in the outlet waste gas is far below the national emission standards, as confirmed by an online methylamine concentration monitoring instrument.

[0015] II. Achieving Resource Recycling, Cost Reduction and Efficiency Improvement: The system innovatively integrates raw material recycling functionality. An online density meter automatically monitors the concentration of the absorbent in the first-stage absorption tower, controlling the discharge pump to deliver a high-concentration methylamine aqueous solution to a concentrated amine water storage tank. This concentrated amine water can be directly reused in upstream production processes such as the methylamination reaction of hydroxyacetonitrile, turning waste into treasure. This significantly reduces the consumption of fresh methylamine raw materials and wastewater treatment costs, achieving green circular production.

[0016] III. Stable and Controllable Operation, Energy Saving and Environmentally Friendly: Each stage of the absorption tower is equipped with an independent plate heat exchanger and circulating pump, allowing for precise and independent control of the absorbent temperature and circulation flow rate at each stage. Through glass rotor flow meters and regulating valves, each stage operates at the optimal absorption temperature, maximizing absorption efficiency and minimizing system energy consumption. The entire system is constructed of 316L stainless steel or fiberglass, offering excellent corrosion resistance and a long service life. The entire process is closed-loop, eliminating secondary pollution. Attached Figure Description

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] Figure 1 This is a schematic diagram of the overall device of this utility model; In the diagram: 1. First-stage absorption tower; 101. Waste gas inlet; 2. Second-stage absorption tower; 3. Third-stage absorption tower; 4. Fourth-stage absorption tower; 5. Fifth-stage absorption tower; 6. Exhaust fan; 7. Tail gas emission pipe; 8. Liquid seal tank; 9. Circulating pump; 10. Plate heat exchanger; 11. Spray device; 12. First-stage overflow pipe; 13. Second-stage overflow pipe; 14. Third-stage overflow pipe; 15. Fourth-stage overflow pipe; 16. Concentrated amine water storage tank; 17. Makeup water pipeline; 18. Discharge pump; 19. Online density meter; 20. Chilled water supply pipe; 21. Chilled water return pipe; 22. Online methylamine concentration monitor; 23. Glass rotor flow meter; 24. Control valve. Detailed Implementation

[0019] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this utility model.

[0020] For examples, please refer to Figure 1This utility model provides a technical solution: a five-stage water absorption tower system for treating methylamine waste gas, including a first-stage absorption tower 1, a second-stage absorption tower 2, a third-stage absorption tower 3, a fourth-stage absorption tower 4 and a fifth-stage absorption tower 5 connected in series by pipelines, as well as an induced draft fan 6, a tail gas emission pipe 7 and an absorption liquid circulation system. The bottom of the first-stage absorption tower 1 is equipped with a waste gas inlet 101 for receiving methylamine-containing waste gas from the production workshop; The top of the fifth-stage absorption tower 5 is equipped with a purified gas outlet, which is connected to the exhaust gas pipe 7 via an induced draft fan 6; The absorbent circulation system includes a liquid seal tank 8, a circulation pump 9, a plate heat exchanger 10, and a spray device 11, all located at the bottom of each absorption tower. The spray device 11 is installed at the top inside each absorption tower and is connected to the liquid seal tank 8 at the bottom of the corresponding tower through the circulation pump 9 to form an independent closed loop circulation. Plate heat exchanger 10 is connected in series in the pipeline between the outlet of circulating pump 9 and spray device 11 to control the temperature of the absorbent liquid.

[0021] The first-stage absorption tower 1 and the fifth-stage absorption tower 5 adopt an empty tower spray structure, and the tower is filled with Pall ring packing.

[0022] The second-stage absorption tower 2, the third-stage absorption tower 3, and the fourth-stage absorption tower 4 are all packed towers, filled with high-efficiency structured packing.

[0023] The liquid seal tank 8 of the first-stage absorption tower 1 is connected to the liquid seal tank 8 of the second-stage absorption tower 2 through the first-stage overflow pipe 12. The liquid seal tank 8 of the second-stage absorption tower 2 is connected to the liquid seal tank 8 of the third-stage absorption tower 3 through the second-stage overflow pipe 13. This process continues until the fourth-stage overflow pipe 15 connects the liquid seal tank 8 of the fourth-stage absorption tower 4 to the liquid seal tank 8 of the fifth-stage absorption tower 5, forming a countercurrent overflow path for the absorbent liquid.

[0024] It also includes a concentrated amine water storage tank 16 and a water replenishment pipeline 17; the liquid inlet of the concentrated amine water storage tank 16 is connected to the bottom of the liquid seal tank 8 of the first-stage absorption tower 1 through a discharge pump 18 and a pipeline. The water supply pipeline 17 is connected to the liquid seal tank 8 of the fifth-stage absorption tower 5 and is used to replenish fresh process water into the system.

[0025] The liquid seal tank 8 of the first-stage absorption tower 1 is equipped with an online density meter 19, which is used to monitor the concentration of methylamine in the absorption liquid and to control the start and stop of the discharge pump 18.

[0026] The plate heat exchanger 10 has a chilled water supply pipe 20 connected to the refrigerant inlet and a chilled water return pipe 21 connected to the refrigerant outlet, which is used to provide a low-temperature cold source for the absorbent.

[0027] An online methylamine concentration monitor 22 is installed on the exhaust pipe 7.

[0028] Glass rotor flowmeters 23 and regulating valves 24 are installed on the outlet pipes of the circulating pumps 9 of each absorption tower.

[0029] The overall system frame, tower body, and pipelines are made of 316L stainless steel or fiberglass.

[0030] The working principle and usage process of this utility model are as follows: First, the methylamine-containing waste gas from the amination and hydrolysis reactors of the production workshop, such as the monohydrate creatine production line, enters the first-stage absorption tower 1 from the bottom through the waste gas inlet 101.

[0031] As the exhaust gas rises within the tower, it comes into countercurrent contact with the low-temperature absorbent process water sprayed from the top spray device 11. Methylamine gas is highly soluble in water and is largely absorbed and dissolved during this process, forming an aqueous methylamine solution. The absorption reaction is exothermic; chilled water 20 / 21 is introduced through the plate heat exchanger 10 to cool the circulating absorbent, maintaining a low operating temperature, typically controlled between 10-40℃. This helps improve the absorption efficiency of methylamine and reduces amine volatilization caused by temperature increases.

[0032] After the first stage of absorption, the concentration of the waste gas is reduced, and then it sequentially enters the second stage (2), third stage (3), and fourth stage (4) absorption towers for further purification. These towers are filled with highly efficient structured packing, which greatly increases the gas-liquid contact area, resulting in high mass transfer efficiency and ensuring that methylamine in the waste gas is fully removed.

[0033] Finally, the exhaust gas enters the fifth-stage absorption tower 5, where it undergoes final washing with fresh process water supplied by the makeup water pipe 17, ensuring that the methylamine in the exhaust gas is completely absorbed. The purified, compliant gas is then drawn into the atmosphere through the exhaust pipe 7 by the induced draft fan 6. An online methylamine concentration monitor 22 installed at the emission outlet monitors emission indicators in real time to ensure compliance with environmental regulations.

[0034] The flow path of the absorbent is opposite to that of the waste gas, employing a counter-current design: fresh process water is added from the liquid seal tank 8 of the fifth-stage absorber 5, and overflows forward stage by stage through the fourth-stage overflow pipe 15, the third-stage overflow pipe 14, the second-stage overflow pipe 13, and the first-stage overflow pipe 12. During this process, the water concentration gradually increases, becoming a high-concentration methylamine aqueous solution by the time it reaches the first-stage absorber 1.

[0035] When the concentration of the methylamine aqueous solution in the liquid seal tank 8 of the first-stage absorption tower 1 reaches the set value and is monitored by the online density meter 19, the discharge pump 18 automatically starts, transporting the concentrated methylamine aqueous solution to the concentrated methylamine water storage tank 16 for storage. This portion of the recovered concentrated methylamine water can be directly returned to the production process, such as the methylamine reaction section, as raw material, realizing the recycling of resources and reducing raw material consumption and waste generation from the source.

[0036] Each absorption tower is equipped with an independent circulation system, including a circulation pump 9, a plate heat exchanger 10, and a spray device 11. The circulation flow rate and cooling intensity can be independently adjusted according to the load and temperature rise of each level through a glass rotor flow meter 23 and a regulating valve 24, so that the entire system always operates under optimal conditions, ensuring the high efficiency and stability of the treatment effect.

[0037] The above are merely preferred embodiments of the present utility model and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A five-stage water absorption tower system for treating methylamine waste gas, characterized in that, It includes a first-stage absorption tower (1), a second-stage absorption tower (2), a third-stage absorption tower (3), a fourth-stage absorption tower (4), and a fifth-stage absorption tower (5) connected in series by pipelines, as well as an induced draft fan (6), a tail gas emission pipe (7), and an absorption liquid circulation system; The bottom of the first-stage absorption tower (1) is provided with a waste gas inlet (101) for receiving methylamine-containing waste gas from the production workshop; The top of the fifth-stage absorption tower (5) is provided with a purified gas outlet, which is connected to the exhaust gas pipe (7) through an induced draft fan (6); The absorbent circulation system includes a liquid seal tank (8) installed at the bottom of each absorption tower, a circulation pump (9), a plate heat exchanger (10), and a spray device (11). The spraying device (11) is installed at the top of the inside of each absorption tower and is connected to the liquid seal tank (8) at the bottom of the corresponding tower through the circulation pump (9) to form an independent closed loop circulation; The plate heat exchanger (10) is connected in series in the pipeline between the outlet of the circulating pump (9) and the spray device (11) to control the temperature of the absorbent liquid.

2. The five-stage water absorption tower system for treating methylamine waste gas according to claim 1, characterized in that, The first-stage absorption tower (1) and the fifth-stage absorption tower (5) adopt an empty tower spray structure, and the tower is filled with Pall ring packing.

3. The five-stage water absorption tower system for treating methylamine waste gas according to claim 2, characterized in that, The second-stage absorption tower (2), the third-stage absorption tower (3), and the fourth-stage absorption tower (4) are all packed towers, and their interiors are filled with highly efficient structured packing.

4. The five-stage water absorption tower system for treating methylamine waste gas according to claim 3, characterized in that, The liquid seal tank (8) of the first-stage absorption tower (1) is connected to the liquid seal tank (8) of the second-stage absorption tower (2) through the first-stage overflow pipe (12). The liquid seal tank (8) of the second-stage absorption tower (2) is connected to the liquid seal tank (8) of the third-stage absorption tower (3) through the second-stage overflow pipe (13). This process continues until the fourth-stage overflow pipe (15) connects the liquid seal tank (8) of the fourth-stage absorption tower (4) to the liquid seal tank (8) of the fifth-stage absorption tower (5), forming a countercurrent overflow path for the absorbent liquid.

5. The five-stage water absorption tower system for treating methylamine waste gas according to claim 1, characterized in that, It also includes a concentrated amine water storage tank (16) and a water replenishment pipeline (17); the inlet of the concentrated amine water storage tank (16) is connected to the bottom of the liquid seal tank (8) of the first-stage absorption tower (1) through a discharge pump (18) and a pipeline; the water replenishment pipeline (17) is connected to the liquid seal tank (8) of the fifth-stage absorption tower (5) and is used to replenish fresh process water into the system.

6. The five-stage water absorption tower system for treating methylamine waste gas according to claim 5, characterized in that, An online density meter (19) is installed in the liquid seal tank (8) of the first-stage absorption tower (1) to monitor the concentration of methylamine in the absorption liquid and to control the start and stop of the discharge pump (18).

7. The five-stage water absorption tower system for treating methylamine waste gas according to claim 1, characterized in that, The plate heat exchanger (10) is connected to a chilled water supply pipe (20) at the refrigerant inlet and to a chilled water return pipe (21) at the refrigerant outlet, which is used to provide a low-temperature cold source for the absorbent.

8. The five-stage water absorption tower system for treating methylamine waste gas according to claim 1, characterized in that, An online methylamine concentration monitor (22) is installed on the exhaust pipe (7).

9. The five-stage water absorption tower system for treating methylamine waste gas according to claim 1, characterized in that, Glass rotor flowmeters (23) and regulating valves (24) are installed on the outlet pipes of the circulating pumps (9) of each absorption tower.

10. The five-stage water absorption tower system for treating methylamine waste gas according to claim 1, characterized in that, The overall frame, tower body, and pipelines of the system are made of 316L stainless steel or fiberglass.

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