Water-soluble gas recovery system and recovery method

Abstract

The invention discloses a water-soluble gas recovery system and method.The water-soluble gas recovery system comprises a buffer tank, a first-stage absorption tower, a second-stage absorption tower, a third-stage absorption tower, a demister, an induced draft fan and a discharging circulating pump, a third spraying mechanism is arranged in the third-stage absorption tower, and the lower end of the third-stage absorption tower communicates with the upper end of the second-stage absorption tower; a second spraying mechanism is arranged in the second-stage absorption tower, an air supply pipe and an overflow pipe are connected between the second-stage absorption tower and the buffer tank, the joint of the air supply pipe and the second-stage absorption tower is higher than the joint of the overflow pipe and the second-stage absorption tower, and the lower end of the first-stage absorption tower is communicated with the upper end of the buffer tank. According to the invention, the absorption liquid and the gas can be fully contacted, so that the water-soluble gas can be effectively absorbed.

Description

Technical Field

[0001] The present invention relates to the technical field of gas recovery, and more specifically, to a water-soluble gas recovery system and a recovery method. Background Art

[0002] In today's industrial production and daily life, the emission and treatment of water-soluble gases has become an increasingly key issue. With the rapid development of industrialization, a large number of gases are produced in the production process in many fields such as chemical, pharmaceutical, and food processing, including water-soluble gases such as ammonia, hydrogen chloride, and sulfur dioxide. Once these water-soluble gases that have not been properly recovered and treated are released into the atmosphere, they will combine with water vapor in the air to form severe meteorological conditions such as acid rain, causing serious corrosion and damage to ecosystems such as soil, water bodies, and vegetation, threatening biodiversity. For example, sulfur dioxide dissolves in water to form sulfurous acid. After acid rain falls on the surface, it can acidify the soil, lead to reduced crop yields, and damage the surface of buildings. Many water-soluble gases are themselves high-value chemical raw materials. Take ammonia as an example. It is one of the core raw materials for making fertilizers. If it is directly discharged, it will not only waste resources, but also increase the cost and energy consumption of subsequent raw material acquisition. As the concept of sustainable development has become popular, companies are facing urgent pressure to reduce raw material consumption and increase resource recycling rates. Recycling water-soluble gases for reproduction is crucial.

[0003] Many existing water-soluble gas recovery systems have poor absorption efficiency. Although traditional absorption tower devices are widely used, the contact between gas and absorption liquid is often not sufficient, and there are problems such as limited gas-liquid mass transfer area and uneven gas-liquid mixing. As a result, some water-soluble gases cannot be effectively captured and absorbed, and still escape into the atmosphere, and the ideal emission reduction effect cannot be achieved. Its large footprint makes it difficult to place equipment in some factories or laboratories with limited space. In addition, a large footprint may also increase construction costs, making the overall production process or experimental process less compact and efficient. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a water-soluble gas recovery system and a recovery method.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] The invention discloses a water-soluble gas recovery system, comprising a buffer tank, a primary absorption tower, a secondary absorption tower, a tertiary absorption tower, a demister, an induced draft fan and a discharge circulation pump, a spray mechanism three is arranged in the tertiary absorption tower, the lower end of the tertiary absorption tower is connected with the upper end of the secondary absorption tower, a spray mechanism two is arranged in the secondary absorption tower, an air supply pipe and an overflow pipe are connected between the secondary absorption tower and the buffer tank, the height of the connection between the air supply pipe and the secondary absorption tower is higher than the connection between the overflow pipe and the secondary absorption tower, the lower end of the primary absorption tower is connected with the upper end of the buffer tank, a liquid phase outlet is arranged at the bottom of the buffer tank, the liquid phase outlet on the buffer tank is connected with the inlet of the discharge circulation pump through a pipeline, the outlet of the discharge circulation pump is connected with the spray mechanism one and the spray mechanism two through a pipeline, the upper end of the tertiary absorption tower is connected with the demister, the induced draft fan and the demister are connected with the pipeline, and an air inlet is arranged on the primary absorption tower.

[0007] Furthermore, the buffer tank, the primary absorption tower, the secondary absorption tower, the tertiary absorption tower and the demister are an integrated structure.

[0008] Furthermore, a heat exchanger is installed in the first-stage absorption tower, and the heat exchanger includes an upper mounting plate and a lower mounting plate installed in the first-stage absorption tower, and a plurality of heat exchange tubes are installed between the upper mounting plate and the lower mounting plate, and the heat exchange tubes include an outer tube, and an inner tube is installed in the outer tube, and the inner tube includes a plurality of arc plates distributed in a circular shape, and fixed blocks are installed at both ends of the arc plates, and a rubber sheet is installed between two adjacent arc plates, and both ends of the rubber sheet are fixed in the fixed blocks.

[0009] It also includes a circulating water inlet main pipe and a circulating water outlet main pipe. The circulating water inlet main pipe is connected to the lower part of each heat exchange tube, and the circulating water outlet main pipe is connected to the upper part of each heat exchange tube.

[0010] Furthermore, the straight pipe at one end of the gas supply pipe connected to the secondary absorption tower is inclined upward by 3°.

[0011] Furthermore, a U-shaped water seal is provided on the overflow pipe, and the U-shaped water seal is located near the connection between the overflow pipe and the buffer tank.

[0012] Furthermore, packing layers are provided in the secondary absorption tower and the tertiary absorption tower.

[0013] A water-soluble gas recovery method comprises the following steps: the gas enters a primary absorption tower from a gas phase inlet through a pipeline, is sprayed and cooled by a spray mechanism, and then enters a buffer tank, where gas-liquid separation is achieved;

[0014] The gas phase enters the secondary absorption tower through the gas supply pipe, and after being sprayed and absorbed by the spray mechanism 2, it enters the bottom of the tertiary absorption tower from the top of the secondary absorption tower;

[0015] The absorption liquid enters the spray mechanism 3 from the absorption liquid system through the pipeline. After the gas phase in the three-stage absorption tower is sprayed and absorbed by the spray mechanism 3, it is defoamed by the defoamer from the top of the three-stage absorption tower and discharged through the induced draft fan.

[0016] The liquid produced after spray absorption in the tertiary absorption tower and the secondary absorption tower falls into the bottom of the secondary absorption tower, and overflows into the buffer tank through the overflow pipe after temporary storage. The liquid in the buffer tank is pumped out by the discharge circulation pump.

[0017] Furthermore, the liquid in the buffer tank is pumped into the spray mechanism 2 and the spray mechanism 1 through the discharge circulation pump to form a circulating absorption system.

[0018] The beneficial effect of the present invention is that after multiple spraying treatments, the gas and the absorption liquid are fully contacted, and the water-soluble gas can be effectively captured. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of a structure of a water-soluble gas recovery system in this embodiment;

[0020] Figure 2 Schematic diagram of a part of the structure of the water-soluble gas recovery system in this embodiment;

[0021] Figure 3 is a cross-sectional view of the heat exchanger in this embodiment;

[0022] Figure 4 is a cross-sectional view of the heat exchanger in this embodiment;

[0023] Figure 5 A cross-sectional view of the heat exchange tube near the upper end in this embodiment;

[0024] Figure 6 This is a cross-sectional view of the heat exchange tube near the lower end in this embodiment.

[0025] Figure numerals: 1, buffer tank; 2, primary absorption tower; 3, secondary absorption tower; 4, tertiary absorption tower; 5, demister; 6, induced draft fan; 7, discharge circulation pump; 8, spray mechanism three; 9, spray mechanism two; 10, spray mechanism one; 11, absorption liquid system; 12, gas phase inlet; 13, discharge port; 14, circulating water inlet main pipe; 15, circulating water outlet main pipe; 16, U-shaped water seal; 17, water inlet flow regulating valve ; 18. Thermometer; 19. Liquid level meter; 20. Discharge flow control valve; 21. Gas phase inlet pipe pressure gauge; 22. Frequency converter; 23. Concentration analyzer; 24. Absorption liquid inlet flow control valve; 25. Flow meter; 26. Draft fan inlet pressure gauge; 27. Upper mounting plate; 28. Lower mounting plate; 29. ​​Heat exchange tube; 30. Outer tube; 31. Inner tube; 32. Curved plate; 33. Fixed block; 34. Rubber sheet. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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] like Figure 1-Figure 5 As shown, a water-soluble gas recovery system includes a buffer tank 1, a primary absorption tower 2, a secondary absorption tower 3, a tertiary absorption tower 4, a demister 5, an induced draft fan 6 and a discharge circulation pump 7. The buffer tank 1, the primary absorption tower 2, the secondary absorption tower 3, the tertiary absorption tower 4 and the demister 5 are an integrated structure, and the floor space occupied is greatly reduced.

[0028] A spray mechanism 3 8 is provided near the upper end of the tertiary absorption tower 4, and the spray mechanism 3 8 is connected to the absorption liquid system 11, and the absorption liquid system 11 provides new absorption liquid. A demister 5 is connected to the upper end of the tertiary absorption tower 4, and the induced draft fan 6 and the demister 5 are connected through a pipeline. The lower end of the tertiary absorption tower 4 is connected to the upper end of the secondary absorption tower 3, and a spray mechanism 2 9 is provided near the upper end of the secondary absorption tower 3, and an overflow pipe is connected between the secondary absorption tower 3 and the buffer tank 1. A U-shaped water seal 16 is provided on the overflow pipe, and the U-shaped water seal 16 is located near the connection between the overflow pipe and the buffer tank 1. The U-shaped water seal 16 can prevent gas from passing through the overflow pipe, and avoid gas cross-talk between the buffer tank 1 and the secondary absorption tower 3. The height of the U-shaped water seal 16 is 400mm. The liquid in the tertiary absorption tower 4 and the secondary absorption tower 3 is temporarily stored at the bottom of the secondary absorption tower 3, and when the liquid reaches a certain height, it overflows to the buffer tank 1 through the overflow pipe. A packing layer is arranged inside the secondary absorption tower 3 and the tertiary absorption tower 4 to provide sufficient contact surface for gas and liquid phases, and the height of the packing layer is 2000 mm.

[0029] The pipeline connecting the induced draft fan 6 and the demister 5 is provided with a concentration analyzer 23 and an induced draft fan inlet pressure gauge 26, and the pipeline connecting the absorption liquid system 11 and the spray mechanism 3 8 is provided with an absorption liquid inlet flow regulating valve 24 and a flow meter 25, and the absorption liquid inlet flow regulating valve 24 is electrically connected to the concentration analyzer 23. The concentration of the water-soluble gas in the exhaust gas is detected by the concentration analyzer 23. When the concentration is higher than the set value, the absorption liquid inlet flow regulating valve 24 is controlled to increase the opening degree, so that the amount of absorption liquid entering the spray mechanism 3 8 is increased to absorb more water-soluble gas.

[0030] An air supply pipe is connected between the secondary absorption tower 3 and the buffer tank 1. The height of the connection between the air supply pipe and the secondary absorption tower 3 is higher than the connection between the overflow pipe and the secondary absorption tower 3. The straight pipe at one end of the air supply pipe connected to the secondary absorption tower 3 is tilted upward by 3° to prevent the gas phase condensate from blocking the pipeline. The lower end of the primary absorption tower 2 is connected to the upper end of the buffer tank 1. The primary absorption tower 2 and the secondary absorption tower 3 are isolated. A liquid phase outlet is provided at the lower part of the buffer tank 1. The liquid phase outlet on the buffer tank 1 is connected to the inlet of the discharge circulation pump 7 through a pipeline. The outlet of the discharge circulation pump 7 is connected to the spray mechanism 10 and the spray mechanism 2 9 through a pipeline. The liquid in the buffer tank 1 can be pumped into the spray mechanism 10 and the spray mechanism 2 9 through the discharge circulation pump 7 to realize the circulation absorption of the liquid and increase the utilization rate of the liquid. The outlet of the discharge circulation pump 7 is also connected to the discharge port 13 via a pipeline. The absorption liquid in the buffer tank 1 can be pumped out from the discharge port 13 through the discharge circulation pump 7 to complete the recovery of the absorption liquid containing water-soluble gas. The absorption liquid and the water-soluble gas can be separated later.

[0031] The primary absorption tower 2 is provided with an air inlet, the height of which is lower than the spray mechanism 10. The air inlet is connected to the gas phase inlet 12 via a pipeline, and the gas to be treated enters the primary absorption tower 2 from the gas phase inlet 12 through the pipeline and the air inlet.

[0032] like Figure 3-Figure 6 As shown, in one embodiment, a heat exchanger is installed in the primary absorption tower 2, and the heat exchanger includes an upper mounting plate 27 and a lower mounting plate 28 installed in the primary absorption tower 2, the upper mounting plate 27 is located above the lower mounting plate 28, and a plurality of heat exchange tubes 29 are installed between the upper mounting plate 27 and the lower mounting plate 28, and the plurality of heat exchange tubes 29 are evenly distributed, and the heat exchange tubes 29 include an outer tube 30, and an inner tube 31 is installed in the outer tube 30. The two ends of the outer tube 30 are respectively located in the upper mounting plate 27 and the lower mounting plate 28, and the two ends of the outer tube 30 are installed with sealing rings, and the inner wall of the sealing ring is sealed and connected with the outer wall of the inner tube 31. The inner tube 31 includes a plurality of arc plates 32 distributed in a circumferential shape, and the two ends of the arc plates 32 are installed with fixing blocks 33, and a rubber sheet 34 is installed between two adjacent arc plates 32, and the two ends of the rubber sheet 34 are fixed in the fixing blocks 33. The heat exchanger further includes a circulating water inlet main pipe 14 and a circulating water outlet main pipe 15. The circulating water inlet main pipe 14 is connected to the lower part of each heat exchange tube 29, and the circulating water outlet main pipe 15 is connected to the upper part of each heat exchange tube 29. The cooling water flows through the gap between the inner tube 31 and the outer tube 30, and the gas flows through the inside of the inner tube 31. In this process, the cooling water and the gas exchange heat to cool the gas.

[0033] The width of the rubber sheet 34 gradually increases, and the width of the rubber sheet 34 near the upper end of the heat exchange tube 29 is smaller than the width of the rubber sheet near the lower end of the heat exchange tube 29. The rubber sheet 34 with a larger width has a stronger deformation ability and can protrude a greater height inward. In this way, the inner diameter of the heat exchange tube 29 gradually decreases from top to bottom. When the gas passes through the heat exchange tube 29 of this structure, the gas pressure will drop, which will also cause the temperature of the gas to drop.

[0034] A water inlet flow regulating valve 17 is provided on the circulating water inlet main pipe 14, and a thermometer 18 is provided on the buffer tank 1. The water inlet flow regulating valve 17 adjusts the flow rate accordingly according to the temperature in the buffer tank 1 detected by the thermometer 18. When the thermometer 18 detects that the temperature of the gas in the buffer tank 1 exceeds the preset value, the opening of the water inlet flow regulating valve 17 is increased, so that more cooling water enters between the inner tube 31 and the outer tube 30. At this time, the increase in water inflow will cause the water pressure to increase, and the rubber sheet 34 can be deformed and bulged toward the center of the inner tube 31. In this way, the diameter of the inner tube 31 can be reduced, so that the time for the gas to pass through is slowed down, and the heat exchange time with the cooling water is increased; secondly, the contact area between the inner tube 31 and the gas can be increased, and the heat exchange area can be increased to improve the heat exchange efficiency, thereby enhancing the cooling effect on the gas, so that the temperature of the gas is maintained below the set value, and the absorption process is better completed.

[0035] In another embodiment, a shell-and-tube heat exchanger is installed in the primary absorption tower 2 to reduce the gas phase temperature. The two ends of the shell-and-tube heat exchanger are respectively connected to the circulating water inlet main pipe 14 and the circulating water outlet main pipe 15, and the circulating water inlet main pipe 14 is located below the circulating water outlet main pipe 15. The circulating water inlet main pipe 14 is provided with an inlet flow regulating valve 17, and the buffer tank 1 is provided with a thermometer 18. The inlet flow regulating valve 17 adjusts the flow rate according to the temperature of the gas in the buffer tank 1 detected by the thermometer 18, ensuring that the temperature of the gas meets the corresponding requirements and achieves the maximum absorption rate effect.

[0036] A liquid level meter 19 is provided on the buffer tank 1, and a discharge flow regulating valve 20 is provided on the pipeline connecting the discharge circulation pump 7 and the discharge port 13. The discharge flow regulating valve 20 is associated with the liquid level meter 19. When the liquid level meter 19 detects that the liquid level in the buffer tank 1 is higher than the set value, the opening of the discharge flow regulating valve 20 becomes larger and the delivery volume increases.

[0037] The recovery system also includes a frequency conversion regulator 22, which controls the induced draft fan 6. A gas phase inlet pipe pressure gauge 21 is provided on the pipeline connecting the gas phase inlet 12 and the first-level absorption tower 2. The frequency conversion regulator 22 is associated with the gas phase inlet pipe pressure gauge 21. When the gas phase inlet pipe pressure gauge 21 detects that the pressure rises above the preset value, the frequency conversion regulator 22 controls the induced draft fan 6 to increase its operating frequency and increase the discharge volume to ensure the pressure stability in the system.

[0038] A method for recovering water-soluble gas comprises the following steps:

[0039] The gas to be treated enters the upper position of the primary absorption tower 2 from the gas phase inlet 12 through the pipeline and the air inlet. The gas passes through the primary absorption tower 2 from top to bottom. The heat exchanger in the primary absorption tower 2 exchanges heat for the gas, cools the gas entering the primary absorption tower 2, and reduces the gas temperature to an appropriate range, thereby reducing the risk of equipment damage and improving recovery efficiency.

[0040] The spray mechanism 10 sprays to absorb the water-soluble gas in the gas. The gas and liquid in the primary absorption tower 2 enter the buffer tank 1, and the gas-liquid separation is realized in the buffer tank 1.

[0041] The gas phase enters the secondary absorption tower 3 through the gas supply pipe, is sprayed by the spray mechanism 2 9, and the water-soluble gas therein is absorbed. The gas phase then enters the bottom of the tertiary absorption tower 4 from the top of the secondary absorption tower 3.

[0042] The absorption liquid enters the spray mechanism 3 8 from the absorption liquid system 11 through the pipeline and is then sprayed out to spray and absorb the gas phase in the tertiary absorption tower 4. The remaining gas after the absorption treatment is removed from the top of the tertiary absorption tower 4 by the demister 5 and then discharged through the induced draft fan 6.

[0043] The liquid generated after spraying absorption in the tertiary absorption tower 4 and the secondary absorption tower 3 falls into the bottom of the secondary absorption tower 3 for temporary storage. When the amount of liquid increases, it overflows into the buffer tank 1 through the overflow pipe. The liquid in the buffer tank 1 is pumped into the spray mechanism 2 9 and the spray mechanism 1 10 through the discharge circulation pump 7 for use, and the water-soluble gas is continuously absorbed to form a circulating absorption system, so as to make fuller use of the liquid.

[0044] When the amount of liquid in the buffer tank 1 reaches the set value, it is pumped out of the system through the discharging circulation pump 7. These liquids absorb the water-soluble gas, that is, the recovery of the water-soluble gas is completed.

[0045] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A water-soluble gas recovery system, characterized in that: The invention comprises a buffer tank (1), a primary absorption tower (2), a secondary absorption tower (3), a tertiary absorption tower (4), a demister (5), an induced draft fan (6) and a discharge circulation pump (7), wherein a third spray mechanism (8) is arranged in the tertiary absorption tower (4), the lower end of the tertiary absorption tower (4) is connected to the upper end of the secondary absorption tower (3), a second spray mechanism (9) is arranged in the secondary absorption tower (3), an air supply pipe and an overflow pipe are connected between the secondary absorption tower (3) and the buffer tank (1), and the height of the connection between the air supply pipe and the secondary absorption tower (3) is higher than that between the overflow pipe and the At the connection point of the secondary absorption tower (3), the lower end of the primary absorption tower (2) is connected to the upper end of the buffer tank (1), the lower part of the buffer tank (1) is provided with a liquid phase outlet, the liquid phase outlet on the buffer tank (1) is connected to the inlet of the discharge circulation pump (7) via a pipeline, the outlet of the discharge circulation pump (7) is connected to the spray mechanism 1 (10) and the spray mechanism 2 (9) via a pipeline, the upper end of the tertiary absorption tower (4) is connected to a demister (5), the induced draft fan (6) and the demister (5) are connected via a pipeline, and the primary absorption tower (2) is provided with an air inlet.

2. A water-soluble gas recovery system according to claim 1, characterized in that: The buffer tank (1), the primary absorption tower (2), the secondary absorption tower (3), the tertiary absorption tower (4) and the demister (5) are an integrated structure.

3. A water-soluble gas recovery system according to claim 1, characterized in that: A heat exchanger is installed in the primary absorption tower (2), the heat exchanger comprising an upper mounting plate (27) and a lower mounting plate (28) installed in the primary absorption tower (2), a plurality of heat exchange tubes (29) are installed between the upper mounting plate (27) and the lower mounting plate (28), the heat exchange tubes (29) comprising an outer tube (30), an inner tube (31) is installed in the outer tube (30), the inner tube (31) comprises a plurality of arc-shaped plates (32) distributed in a circumferential shape, Both ends of the arc-shaped plate (32) are installed with fixed blocks (33), and a rubber sheet (34) is installed between two adjacent arc-shaped plates (32), and both ends of the rubber sheet (34) are fixed in the fixed blocks (33); and the system also includes a circulating water inlet main pipe (14) and a circulating water outlet main pipe (15), wherein the circulating water inlet main pipe (14) is connected to the lower part of each heat exchange tube (29), and the circulating water outlet main pipe (15) is connected to the upper part of each heat exchange tube (29).

4. A water-soluble gas recovery system according to claim 1, characterized in that: The straight pipe at one end of the gas supply pipe connected to the secondary absorption tower (3) is inclined upward by 3°.

5. A water-soluble gas recovery system according to claim 1, characterized in that: The overflow pipe is provided with a U-shaped water seal (16), and the U-shaped water seal (16) is located near the connection between the overflow pipe and the buffer tank (1).

6. A water-soluble gas recovery system according to claim 1, characterized in that: The secondary absorption tower (3) and the tertiary absorption tower (4) are provided with packing layers.

7. A method for recovering water-soluble gas, characterized in that: Using a water-soluble gas recovery system as described in any one of claims 1 to 6, The following steps are included: The gas enters the primary absorption tower (2) from the gas phase inlet (12) through the pipeline, is spray-cooled by the spray mechanism (10), and then enters the buffer tank (1), where gas-liquid separation is achieved; The gas phase enters the secondary absorption tower (3) through the gas supply pipe, is sprayed and absorbed by the second spray mechanism (9), and then enters the bottom of the tertiary absorption tower (4) from the top of the secondary absorption tower (3); The absorption liquid enters the spray mechanism three (8) from the absorption liquid system (11) through the pipeline, and the gas phase in the three-stage absorption tower (4) is sprayed and absorbed by the spray mechanism three (8), and then is defoamed by the defoamer (5) from the top of the three-stage absorption tower (4) and discharged through the induced draft fan (6); The liquid generated after spray absorption in the tertiary absorption tower (4) and the secondary absorption tower (3) falls into the bottom of the secondary absorption tower (3), and overflows into the buffer tank (1) through an overflow pipe after being temporarily stored. The liquid in the buffer tank (1) that has absorbed the water-soluble gas is pumped out through a discharge circulation pump (7), thereby completing the recovery of the water-soluble gas.

8. A water-soluble gas recovery method according to claim 7, characterized in that: The liquid in the buffer tank (1) is pumped into the second spray mechanism (9) and the first spray mechanism (10) via the discharge circulation pump (7) to form a circulating absorption system. After the liquid in the buffer tank (1) that has absorbed the water-soluble gas reaches a set liquid level, it is pumped out via the discharge circulation pump (7) to complete the recovery of the water-soluble gas.

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