Low-temperature normal-pressure evaporation system for coking wastewater treatment

Abstract

The utility model relates to the field of wastewater treatment, and particularly discloses a low-temperature normal-pressure evaporation system for coking wastewater treatment, which comprises a saturation tower, a dehumidification tower communicated with the saturation tower, a first heat exchanger communicated with the dehumidification tower, and a second heat exchanger communicated with the first heat exchanger and the saturation tower, by arranging the saturation tower, the dehumidification tower, the damp and hot carrier gas pipeline and the dry and cold carrier gas pipeline, after damp and hot carrier gas enters the dehumidification tower with the relatively low temperature, due to the fact that the temperature is reduced, the damp and hot carrier gas can be attached to the inner wall of the dehumidification tower, condensate water and dry and cold carrier gas are formed, and evaporation treatment on strong brine is achieved; and after the dry and cold carrier gas enters the saturation tower through the dry and cold carrier gas pipeline, as the initial moisture content of the dry and cold carrier gas is relatively low, the evaporation efficiency of the wastewater is high, energy conservation and consumption reduction can be realized, and waste heat, such as low-grade steam, hot water and flue gas waste heat, which cannot be utilized in a coking plant can be used for heating the wastewater through low-temperature and normal-pressure evaporation, so that the energy is saved. And the energy consumption can be further reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of wastewater treatment, in particular to a low-temperature and normal-pressure evaporation system for coking wastewater treatment. Background Art

[0002] In 2020, China's crude steel output exceeded 1 billion tons for the first time, becoming the first country in the world to reach 1 billion tons of steel annually. Steel production accounts for 56.5% of the global proportion. More than half of the world's crude steel is produced by China. The rapid development of industry has brought serious environmental pollution problems. As the front end of steelmaking, coking wastewater generated by coking plant gas purification, coking and chemical product recovery is one of the most polluted industrial wastewaters. China's annual emissions are about 470 million tons, which poses a huge challenge to water environment protection.

[0003] For the treatment of coking wastewater, first of all, because coking wastewater contains more tar, the first step is to remove the oil. Through the oil removal tank, the oil droplets in the sewage are separated by the difference in oil-water density, and the heavy oil in the sewage is removed. The wastewater after degreasing enters the regulating tank for water quality equalization to ensure the stability of the water inlet of the subsequent treatment unit. At the same time, an accident pool is set up to temporarily store abnormal water inflow, and most of the organic matter, ammonia nitrogen, cyanide, thiocyanide, volatile phenol and other toxic substances in the coking wastewater are aerobically degraded to reduce the toxicity of the wastewater and the burden on the downstream treatment units. The supernatant flows by gravity to the anoxic pool collection well, and is lifted to the anoxic pool by the sewage lifting pump. The denitrifying bacteria in the anoxic pool use the nitrite nitrogen and nitrate nitrogen in the reflux liquid to denitrify and convert the nitrate nitrogen into nitrogen gas, while removing part of the BOD The aerobic tank is the core and key unit of the biological treatment system. The effluent from the anoxic tank and the return sludge from the secondary sedimentation tank are mixed and then enter the aerobic tank. The aerated activated sludge method is adopted. The organic matter is adsorbed and degraded by microorganisms, and the water quality is purified. In the later stage of aeration, nitrification reaction is carried out, and ammonia nitrogen is converted into nitrate nitrogen. The built-in suspended silicone rubber membrane microporous aeration tube is aerated by a Roots blower, and then sent to the denitrification tank. The denitrification tank consists of an anaerobic tank, an aerobic tank and a sedimentation tank. The denitrification tank adopts the A / O process. By adding glucose as a supplementary carbon source in the A tank, the removal capacity of total nitrogen in the wastewater is improved. Aeration in the O tank further removes COD in the wastewater, and then passes through a high-density tank and ozone oxidation, and finally enters the reclaimed water reuse process. 60%-75% of the reclaimed water is reused, and 25%-40% of the concentrated brine is produced;

[0004] For the treatment of concentrated brine, nanofiltration is generally used for salt separation followed by evaporation and crystallization, which then produces sodium chloride and sodium sulfate as by-products. However, evaporation is a common wastewater treatment process and is often used for the concentration and reduction of difficult wastewater. Conventional evaporators such as MVR and three-effect evaporators have the problems of high energy consumption and low wastewater recovery rate. Utility Model Content

[0005] The purpose of the utility model is to provide a low-temperature atmospheric pressure evaporation system for coking wastewater treatment to solve the following technical problems:

[0006] How to solve the problem of high energy consumption and low wastewater recovery rate of conventional evaporators.

[0007] The purpose of the utility model can be achieved through the following technical solutions:

[0008] A low-temperature atmospheric pressure evaporation system for treating coking wastewater, comprising a saturation tower, a dehumidification tower connected to the saturation tower, a first heat exchanger connected to the dehumidification tower, a second heat exchanger connected to the first heat exchanger and the saturation tower, a wastewater inlet connected to the first heat exchanger, a condensed water outlet connected to the first heat exchanger, and a condensed water outlet pipe connected to the first heat exchanger and the dehumidification tower; the temperature in the saturation tower decreases from top to bottom, the temperature in the dehumidification tower increases from top to bottom, a plurality of groups of hot and humid carrier gas pipelines are fixedly connected between the saturation tower and the dehumidification tower, and the saturation tower and the dehumidification tower are connected through the hot and humid carrier gas pipelines. The pipelines are interconnected, and a plurality of groups of air holes are provided on the inner wall at the top of the dehumidification tower. A dry cooling gas carrier pipeline is fixedly connected to the top of the dehumidification tower, and the dry cooling gas carrier pipeline is connected to the air holes. One end of the dry cooling gas carrier pipeline away from the dehumidification tower is connected to the bottom of the saturation tower and the dehumidification tower. A water inlet assembly is fixedly connected to the top of the saturation tower, and the water inlet assembly includes a water inlet bin, a water inlet pipe and a water injection hole. The water inlet pipe is connected to the second heat exchanger. A cooling water delivery pipe is fixedly connected between the condensed water outlet and the dehumidification tower, and the cooling water delivery pipe is fixedly connected to the top of the dehumidification tower. A concentrated liquid outlet is connected to the bottom of the saturation tower.

[0009] In this embodiment, the temperatures in the saturation tower are 90°C, 80°C, 70°C, 60°C and 50°C from top to bottom, respectively, and the temperatures in the dehumidification tower are 45°C, 55°C, 65°C, 75°C and 85°C from top to bottom, respectively. A hot and humid carrier gas pipeline is led out from one side of the 80°C interval in the saturation tower and is connected to the 75°C interval in the dehumidification tower, a hot and humid carrier gas pipeline is led out from one side of the 70°C interval in the saturation tower and is connected to the 65°C interval in the dehumidification tower, and a hot and humid carrier gas pipeline is led out from one side of the 60°C interval in the saturation tower and is connected to the 55°C interval in the dehumidification tower.

[0010] In this embodiment, the temperature of the dry cold carrier gas is 20-45° C., and the dry cold carrier gas can be dry cold air or dry cold nitrogen.

[0011] In this embodiment, after the condensed water generated in the dehumidification tower is processed by the first heat exchanger, part of it is recycled into the dehumidification tower through the cooling water delivery pipe as cooling water, and part of it is delivered to the reclaimed water reuse pool through the condensed water outlet.

[0012] In this embodiment, the water inlet assembly includes a water inlet bin fixedly connected to the top of the saturation tower, a plurality of water injection holes are provided at the bottom of the water inlet bin, the water inlet pipe is fixedly connected to the top of the water inlet bin, two groups of mounting grooves are provided on the inner wall of the water inlet pipe, a plurality of springs are fixedly connected to the top of the two groups of mounting grooves, a sealing plate is fixedly connected to the bottom of the spring, the sealing plate is adapted to the size of the water inlet pipe, a bearing plate is fixedly connected to the bottom of the sealing plate, a plurality of connecting rods are fixedly connected to the bottom of the bearing plate, the connecting rods correspond to the positions of the water injection holes, and a cleaning brush is fixedly connected to the bottom of each connecting rod.

[0013] In this embodiment, both sides of the bottom of the water inlet bin are fixedly connected to limit blocks, the tops of the two groups of limit blocks are fixedly connected to limit rods, and the bearing plate is sleeved outside the two groups of limit rods.

[0014] Beneficial effects of the utility model:

[0015] (1) The utility model sets a saturation tower, a dehumidification tower, a wet hot carrier gas pipeline and a dry cold carrier gas pipeline. After the wet hot carrier gas enters the dehumidification tower with a relatively low temperature, the temperature drops, so the wet hot carrier gas will adhere to the inner wall of the dehumidification tower and form condensed water and dry cold carrier gas, thereby realizing the evaporation treatment of the concentrated brine. After the dry cold carrier gas enters the saturation tower through the dry cold carrier gas pipeline, the initial moisture content of the dry cold carrier gas is low, so the evaporation efficiency of the waste water is high, which can achieve energy saving and consumption reduction. In addition, the low-temperature and normal-pressure evaporation can use the waste heat that cannot be used in the coking plant, such as low-grade steam, hot water, and flue gas waste heat, to heat the waste water, which can further reduce energy consumption.

[0016] (2) The utility model applies downward pressure to the sealing plate through wastewater, thereby driving the support plate on the top thereof to move downward synchronously and stretch the spring. When the support plate moves, the cleaning brush on the top thereof will pass through the water injection hole and move to the bottom of the water injection hole. When the cleaning brush moves downward, it will clean the inner wall of the water injection hole, thereby preventing the crystallization of concentrated brine remaining in the water injection hole and causing blockage, ensuring that the wastewater can quickly enter the saturation tower and preventing heat loss of the wastewater from affecting the evaporation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The utility model is further described below in conjunction with the accompanying drawings.

[0018] Figure 1 This is a structural schematic diagram of a low-temperature and normal-pressure evaporation system for treating coking wastewater in the utility model;

[0019] Figure 2 It is a cross-sectional view of the water inlet bin in the utility model.

[0020] Figure numerals: 1. Saturation tower; 2. Dehumidification tower; 3. Air hole; 4. Water injection hole; 5. First heat exchanger; 6. Second heat exchanger; 7. Wet hot carrier gas pipeline; 8. Dry cold carrier gas pipeline; 9. Condensate outlet pipe; 10. Cooling water delivery pipe; 11. Condensate outlet; 12. Wastewater inlet; 13. Concentrate outlet; 14. Water inlet tank; 15. Water inlet pipe; 16. Spring; 17. Sealing plate; 18. Load-bearing plate; 19. Connecting rod; 20. Cleaning brush; 21. Limit rod. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0022] A low-temperature atmospheric pressure evaporation system for treating coking wastewater in the embodiment of the utility model, please refer to the attached drawing Figure 1 , 2 As shown, it includes a saturation tower 1, a dehumidification tower 2 connected to the saturation tower 1, and also includes a first heat exchanger 5 connected to the dehumidification tower 2, a second heat exchanger 6 connected to the first heat exchanger 5 and the saturation tower 1, a wastewater inlet 12 connected to the first heat exchanger 5, a condensed water outlet 11 connected to the first heat exchanger 5, and a condensed water outlet pipe 9 connected to the first heat exchanger 5 and the dehumidification tower 2. The temperature in the saturation tower 1 decreases from top to bottom, and the temperature in the dehumidification tower 2 increases from top to bottom. A plurality of groups of hot and humid gas carrier pipes 7 are fixedly connected between the saturation tower 1 and the dehumidification tower 2. The saturation tower 1 and the dehumidification tower 2 are connected to each other through the hot and humid gas carrier pipes 7. A plurality of groups of air holes 3 are provided on the inner wall at the top of the wet tower 2, a dry cold carrier gas pipeline 8 is fixedly connected to the top of the dehumidifying tower 2, the dry cold carrier gas pipeline 8 is communicated with the air holes 3, one end of the dry cold carrier gas pipeline 8 away from the dehumidifying tower 2 is communicated with the bottom of the saturation tower 1 and the dehumidifying tower 2, a water inlet assembly is fixedly connected to the top of the saturation tower 1, the water inlet assembly includes a water inlet bin 14, a water inlet pipe 15 and a water injection hole 4, the water inlet pipe 15 is communicated with the second heat exchanger 6, a cooling water delivery pipe 10 is fixedly connected between the condensed water outlet 11 and the dehumidifying tower 2, the cooling water delivery pipe 10 is fixedly connected to the top of the dehumidifying tower 2, and a concentrated liquid outlet 13 is communicated with the bottom of the saturation tower 1;

[0023] The concentrated brine produced by the wastewater treatment of the coking plant is the treatment object of the system. The concentrated brine is first transported to the first heat exchanger 5 through the wastewater inlet 12. The first heat exchanger 5 will preliminarily heat the concentrated brine and then transport it to the second heat exchanger 6. After the concentrated brine enters the second heat exchanger 6, the second heat exchanger 6 will heat the concentrated brine to 90°C and then transport it to the saturation tower 1 through the water inlet pipe 15 and the water inlet component. After the concentrated brine enters the saturation tower 1, the hot and humid carrier gas generated by it will be transported to the dehumidification tower 2 through the hot and humid carrier gas pipeline 7. After the hot and humid carrier gas enters the dehumidification tower 2 with a relatively low temperature, the hot and humid carrier gas will adhere to the inner wall of the dehumidification tower 2 due to the temperature reduction and form condensed water and dry cold carrier gas. Then the condensed water will flow along The wastewater flows downward from the inner wall of the dehumidification tower 2 and is transported to the first heat exchanger 5 through the condensate outlet pipe 9. A part of the generated condensate is reused as cooling water in the low-temperature atmospheric pressure evaporation system, and a part is transported to the reclaimed water reuse pool through a pipeline. The dry cold carrier gas enters the saturation tower 1 through the dry cold carrier gas pipeline 8. The initial moisture content of the dry cold carrier gas is low, so the evaporation efficiency of the wastewater is high, further achieving energy saving and consumption reduction. The concentrated brine in the saturation tower 1 is guided out of the evaporation system through the concentrated liquid outlet 13, enters the thickener for further concentration, and then enters the freezing crystallization system. Sodium sulfate crystallizes in the temperature range of -5 to 5°C, and then is centrifuged to produce sodium sulfate decahydrate solid and crystallization mother liquor. The sodium sulfate decahydrate is further melted and dried to produce sodium sulfate product.

[0024] The low-temperature atmospheric pressure evaporation system provided by the present invention is essentially different from the three-effect and MVR evaporators. It has high tolerance to system structure and foaming of feed liquid, requires simple equipment, has mature technology, high efficiency and low operating cost, and a stable system. It can realize full system automation operation, occupies a small area, saves energy and reduces consumption. When the second heat exchanger 6 is in use, it can use the waste heat of the coking plant, such as low-grade steam, hot water, and flue gas waste heat for heating, which can further reduce the energy consumption of wastewater treatment.

[0025] As an implementation of the present invention, please refer to the attached drawings Figure 1 As shown, specifically, the temperatures in the saturation tower 1 are 90°C, 80°C, 70°C, 60°C and 50°C from top to bottom, respectively, and the temperatures in the dehumidification tower 2 are 45°C, 55°C, 65°C, 75°C and 85°C from top to bottom, respectively, a hot and humid carrier gas pipeline 7 is led out from one side of the 80°C interval in the saturation tower 1 and is connected to the 75°C interval in the dehumidification tower 2, a hot and humid carrier gas pipeline 7 is led out from one side of the 70°C interval in the saturation tower 1 and is connected to the 65°C interval in the dehumidification tower 2, and a hot and humid carrier gas pipeline 7 is led out from one side of the 60°C interval in the saturation tower 1 and is connected to the 55°C interval in the dehumidification tower 2;

[0026] The hot and humid carrier gas inside the saturation tower 1 will be transported to the dehumidification tower 2 through a pipeline. After the hot and humid carrier gas enters the dehumidification tower 2, the temperature becomes lower, so the hot and humid carrier gas will become liquid and condense on the inner wall of the dehumidification tower 2 until it becomes condensed water and is discharged from the bottom of the dehumidification tower 2, thereby realizing the recovery of wastewater. By zoning the temperature, the efficiency of condensed water generation can be improved, thereby improving the efficiency of wastewater treatment.

[0027] As an implementation of the present invention, please refer to the attached drawings Figure 1 As shown, specifically, the temperature of the dry-cooled carrier gas is 20-45°C, and the dry-cooled carrier gas can be one of dry-cooled air or dry-cooled nitrogen. The circulating carrier gas reduces the vapor partial pressure and evaporation temperature of the higher boiling point liquid, and performs stripping, gas lift and evaporation on the higher boiling point liquid, thereby concentrating the higher boiling point liquid into a concentrated liquid. Low-temperature and normal-pressure evaporation can use the waste heat that cannot be used in the coking plant to heat the waste water, which can greatly reduce energy consumption.

[0028] As an implementation of the present invention, please refer to the attached drawings Figure 1 As shown, specifically, after the condensed water generated in the dehumidification tower 2 is processed by the first heat exchanger 5, a part of it is recycled into the dehumidification tower 2 through the cooling water delivery pipe 10 as cooling water, and a part of it is delivered to the reclaimed water reuse pool through the condensed water outlet 11. After the cooling water returns to the dehumidification tower 2, the temperature inside the dehumidification tower 2 can be adjusted to avoid the situation where the temperature inside the dehumidification tower 2 is too high, resulting in the inability to form condensed water after the hot and humid carrier gas enters the dehumidification tower 2, thereby ensuring the normal progress of the concentrated brine treatment operation.

[0029] As an implementation of the present invention, please refer to the attached drawings Figure 2 As shown, specifically, the water inlet assembly includes a water inlet bin 14 fixedly connected to the top of the saturation tower 1, a plurality of water injection holes 4 are provided at the bottom of the water inlet bin 14, the water inlet pipe 15 is fixedly connected to the top of the water inlet bin 14, two groups of mounting grooves are provided on the inner wall of the water inlet pipe 15, a plurality of springs 16 are fixedly connected to the tops of the two groups of mounting grooves, a sealing plate 17 is fixedly connected to the bottom of the spring 16, the sealing plate 17 is adapted to the size of the water inlet pipe 15, a bearing plate 18 is fixedly connected to the bottom of the sealing plate 17, a plurality of connecting rods 19 are fixedly connected to the bottom of the bearing plate 18, the connecting rods 19 correspond to the positions of the water injection holes 4, and a cleaning brush 20 is fixedly connected to the bottom of each connecting rod 19;

[0030] In the initial state, the sealing plate 17 is located in the installation groove to seal the water inlet pipe 15. When performing low-temperature and normal-pressure evaporation operations, the wastewater will be transported to the water inlet pipe 15 after being heated. At this time, the wastewater in the water inlet pipe 15 will exert downward pressure on the sealing plate 17, thereby squeezing the sealing plate 17 downward. In the process of squeezing downward, the sealing plate 17 will drive the support plate on its top to move downward synchronously and stretch the spring 16. When the support plate moves, the cleaning brush 20 on its top will pass through the water injection hole 4 and move to the bottom of the water injection hole 4. When the cleaning brush 20 moves downward, it will clean the inner wall of the water injection hole 4, thereby avoiding the crystallization of concentrated brine remaining in the water injection hole 4 and causing blockage, ensuring that the wastewater can quickly enter the saturation tower 1, and avoiding heat loss of the wastewater affecting the evaporation efficiency;

[0031] When the water inlet is completed once, the sealing plate 17 is no longer squeezed by the wastewater. At this time, the sealing plate 17 will move upward under the action of the elastic restoring force of the spring 16 itself, and move back to the inside of the water inlet pipe 15, and block the water inlet pipe 15, thereby preventing the hot and humid carrier gas in the saturated tower 1 from escaping outward through the water injection hole 4 and the water inlet pipe 15 to cause heat loss, thereby further improving the evaporation efficiency.

[0032] As an implementation method of the utility model, please refer to the accompanying drawings Figure 2 As shown, specifically, both sides of the bottom of the water inlet bin 14 are fixedly connected to limit blocks, the tops of the two groups of limit blocks are fixedly connected to limit rods 21, and the bearing plate 18 is sleeved outside the two groups of limit rods 21;

[0033] When the supporting plate 18 is moving, the limiting rod 21 can limit it, preventing the supporting plate 18 from being skewed during movement, which would cause the cleaning brush 20 to be unable to enter the water injection hole 4, thereby ensuring that the cleaning brush 20 can have a good cleaning effect on the inside of the water injection hole 4, and the limiting block can prevent the supporting plate 18 from being completely fitted with the bottom of the water inlet bin 14 under the action of the wastewater flow, thereby preventing the supporting plate 18 from blocking the water injection hole 4 and preventing the wastewater from flowing down, thereby ensuring the normal implementation of the evaporation operation.

[0034] Working principle: First, the concentrated brine is transported to the first heat exchanger 5 through the wastewater inlet 12. The first heat exchanger 5 will preliminarily heat the concentrated brine and then transport it to the second heat exchanger 6. After the concentrated brine enters the second heat exchanger 6, the second heat exchanger 6 will heat the concentrated brine to 90°C and then transport it to the saturation tower 1 through the water inlet pipe 15 and the water inlet assembly. After the concentrated brine enters the saturation tower 1, the humid hot carrier gas generated by it will be transported to the dehumidification tower 2 through the humid hot carrier gas pipeline 7. After the humid hot carrier gas enters the dehumidification tower 2 with a relatively low temperature, the humid hot carrier gas will adhere to the inner wall of the dehumidification tower 2 due to the decrease in temperature and form condensed water and dry cold carrier gas. Then the condensed water will flow along the inner wall of the dehumidification tower 2 to The wastewater flows downward and is transported to the first heat exchanger 5 through the condensate outlet pipe 9. A part of the generated condensate is reused as cooling water in the low-temperature atmospheric pressure evaporation system, and a part is transported to the reclaimed water reuse pool through a pipeline. The dry cold carrier gas enters the saturation tower 1 through the dry cold carrier gas pipeline 8. The initial moisture content of the dry cold carrier gas is low, so the evaporation efficiency of the wastewater is high, which further achieves energy saving and consumption reduction. The concentrated brine in the saturation tower 1 is guided out of the evaporation system through the concentrated liquid outlet 13, enters the thickener for further concentration, and then enters the freezing crystallization system. In the temperature range of -5 to 5°C, sodium sulfate crystallizes, and then is centrifuged to produce sodium sulfate decahydrate solid and crystallization mother liquor. The sodium sulfate decahydrate is further melted and dried to produce sodium sulfate product.

[0035] The use of circulating carrier gas can reduce the vapor partial pressure and evaporation temperature of the higher boiling point liquid, and the higher boiling point liquid can be stripped, gas-lifted and evaporated, so that the higher boiling point liquid can be concentrated into a concentrated liquid. In addition, low-temperature and normal-pressure evaporation can use waste heat that cannot be used in the coking plant, such as low-grade steam, hot water, and flue gas waste heat to heat the wastewater, which can greatly reduce energy consumption.

[0036] The low-temperature atmospheric pressure evaporation system provided by the present invention is essentially different from the triple-effect and MVR evaporators, and has high tolerance to system structure and liquid foaming, and requires simple equipment, mature technology, high efficiency and low operating cost, stable system, can realize full system automatic operation, small footprint, energy saving and consumption reduction;

[0037] And when performing low-temperature and normal-pressure evaporation operations, the wastewater will be transported to the water inlet pipe 15 after being heated. At this time, the wastewater in the water inlet pipe 15 will exert downward pressure on the sealing plate 17, thereby squeezing the sealing plate 17 downward. In the process of squeezing downward, the sealing plate 17 will drive the support plate on its top to move downward synchronously and stretch the spring 16. When the support plate moves, the cleaning brush 20 on its top will pass through the water injection hole 4 and move to the bottom of the water injection hole 4. When the cleaning brush 20 moves downward, it will clean the inner wall of the water injection hole 4, thereby avoiding blockage caused by crystallization of concentrated brine remaining in the water injection hole 4, ensuring that the wastewater can quickly enter the saturation tower 1, and avoiding heat loss of the wastewater affecting the evaporation efficiency.

[0038] The above is a detailed description of an embodiment of the utility model, but the content is only a preferred embodiment of the utility model and cannot be considered to limit the scope of implementation of the utility model. All equivalent changes and improvements made within the scope of application of the utility model should still fall within the scope of the patent coverage of the utility model.

Claims

1. A low-temperature atmospheric pressure evaporation system for treating coking wastewater, comprising a saturation tower (1) and a dehumidification tower (2) connected to the saturation tower (1), characterized in that: The dehumidifier also includes a first heat exchanger (5) connected to the dehumidification tower (2), a second heat exchanger (6) connected to the first heat exchanger (5) and the saturation tower (1), a wastewater inlet (12) connected to the first heat exchanger (5), a condensate outlet (11) connected to the first heat exchanger (5), and a condensate outlet pipe (9) connected to the first heat exchanger (5) and the dehumidification tower (2). The temperature in the saturation tower (1) decreases from top to bottom, and the temperature in the dehumidification tower (2) increases from top to bottom. A plurality of groups of hot and humid air carrier pipes (7) are fixedly connected between the saturation tower (1) and the dehumidification tower (2). The saturation tower (1) and the dehumidification tower (2) are connected to each other through the hot and humid air carrier pipes (7). The top inner wall of the dehumidification tower (2) is provided with a plurality of groups of gas pipes. The saturation tower (1) is connected to the dehumidification tower (2) by a cooling water delivery pipe (10), the cooling water delivery pipe (10) is connected to the top of the dehumidification tower (2), and the bottom of the saturation tower (1) is connected to the dehumidification tower (2). The saturation tower (1) is connected to the dehumidification tower (2) by a cooling water delivery pipe (10), the cooling water delivery pipe (10) is connected to the top of the dehumidification tower (2), and the bottom of the saturation tower (1) is connected to the concentrated liquid outlet (13).

2. A low-temperature and normal-pressure evaporation system for treating coking wastewater according to claim 1, characterized in that: The temperatures in the saturation tower (1) are respectively 90°C, 80°C, 70°C, 60°C and 50°C from top to bottom, and the temperatures in the dehumidification tower (2) are respectively 45°C, 55°C, 65°C, 75°C and 85°C from top to bottom. A moist heat carrier gas pipeline (7) is led out from one side of the 80°C interval in the saturation tower (1) and is connected to the 75°C interval in the dehumidification tower (2). A moist heat carrier gas pipeline (7) is led out from one side of the 70°C interval in the saturation tower (1) and is connected to the 65°C interval in the dehumidification tower (2). A moist heat carrier gas pipeline (7) is led out from one side of the 60°C interval in the saturation tower (1) and is connected to the 55°C interval in the dehumidification tower (2).

3. A low-temperature and normal-pressure evaporation system for treating coking wastewater according to claim 2, characterized in that: The temperature of the dry cold carrier gas is 20-45° C., and the dry cold carrier gas can be dry cold air or dry cold nitrogen.

4. A low-temperature and normal-pressure evaporation system for treating coking wastewater according to claim 3, characterized in that: After the condensed water generated in the dehumidification tower (2) is processed by the first heat exchanger (5), a portion of it is recycled into the dehumidification tower (2) as cooling water through the cooling water delivery pipe (10), and a portion of it is delivered to the reclaimed water reuse pool through the condensed water outlet (11).

5. The low-temperature and normal-pressure evaporation system for treating coking wastewater according to claim 1, characterized in that: The water inlet assembly comprises a water inlet bin (14) fixedly connected to the top of the saturation tower (1), the bottom of the water inlet bin (14) is provided with a plurality of water injection holes (4), the water inlet pipe (15) is fixedly connected to the top of the water inlet bin (14), the inner wall of the water inlet pipe (15) is provided with two groups of mounting grooves, the tops of the two groups of mounting grooves are fixedly connected with a plurality of springs (16), the bottom of the springs (16) is fixedly connected with a sealing plate (17), the sealing plate (17) is adapted to the size of the water inlet pipe (15), the bottom of the sealing plate (17) is fixedly connected with a bearing plate (18), the bottom of the bearing plate (18) is fixedly connected with a plurality of connecting rods (19), the connecting rods (19) correspond to the positions of the water injection holes (4), and the bottom of each connecting rod (19) is fixedly connected with a cleaning brush (20).

6. A low-temperature and normal-pressure evaporation system for treating coking wastewater according to claim 5, characterized in that: Both sides of the bottom of the water inlet bin (14) are fixedly connected to limit blocks, the tops of the two groups of limit blocks are fixedly connected to limit rods (21), and the bearing plate (18) is sleeved outside the two groups of limit rods (21).

Images