Open gradient absorption waste water purification system and method

Abstract

The application discloses an open type gradient absorption waste water purification system and method, and relates to the technical field of waste water treatment. The application divides the absorption tower and the regeneration tower into three stages, utilizes the double-stage regenerative module to cooperate with the continuous drainage heater and the steam heater to realize three-stage feed temperature control of waste water, utilizes the double-stage regenerative module to cooperate with the cooler to realize three-stage feed temperature control of purified water, optimizes the fillers of each stage, adopts high-efficiency fillers in the low-temperature and low-speed area, and adopts high-strength fillers in the high-temperature and high-speed area, so that better solutions of overall resistance, efficiency and safety are realized, and the overall heat and mass transfer efficiency can be significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to an open gradient absorption wastewater purification system and method. BACKGROUND

[0002] At present, the open absorption wastewater purification system has been gradually popularized in the market. In the actual operation of the open evaporation absorption wastewater purification system, it is found that the temperature difference and humidity difference of air in the circulation process are large, causing the problem of uneven air flow rate in the tower. Specifically, the heat and mass transfer efficiency in the low-speed area is lower than the average value, and due to the large overall height, the pipeline cavitation problem may occur when the heat source is unstable or in high-altitude areas.

[0003] Therefore, it is urgent to improve the open absorption wastewater purification system to achieve a better solution of overall resistance, efficiency and safety, and avoid the risk of pipeline cavitation in high-altitude areas when the heat source is unstable.

[0004] In view of this, the present application is proposed. SUMMARY

[0005] The present application aims to provide an open gradient absorption wastewater purification system and method, which aims to improve the overall heat and mass transfer efficiency under the premise of ensuring safety performance.

[0006] The present application is implemented as follows:

[0007] In a first aspect, the present application provides an open gradient absorption wastewater purification system, comprising:

[0008] An absorption tower for heat and mass transfer between wastewater and air, so that water in the wastewater enters the air, and the air containing water is output; the absorption tower is sequentially provided with a first absorption filler layer, a second absorption filler layer and a third absorption filler layer from bottom to top;

[0009] A regenerator for heat and mass transfer between the water-containing air generated by the absorption tower and clean water, so that water in the water-containing air enters the clean water, and the air output by the regenerator is circulated to the absorption tower; the regenerator is sequentially provided with a first regenerator filler layer, a second regenerator filler layer and a third regenerator filler layer from bottom to top;

[0010] A two-stage regenerative module, which comprises a first regenerator and a second regenerator; the first regenerator and the second regenerator are both used for heat exchange between clean water and wastewater;

[0011] Part of the waste water output from the bottom of the absorption tower enters the second regenerator for primary heating, and the waste water after primary heating is divided into two paths, one of which enters the first absorption packing layer of the absorption tower, and the other of which enters the first regenerator for secondary heating; the waste water after secondary heating is divided into two paths, one of which enters the second absorption packing layer after being heated by the continuous water heater, and the other of which enters the third absorption packing layer after being heated by the steam heater;

[0012] Part of the clean water output from the bottom of the regeneration tower enters the first regenerator for primary cooling, and the clean water after primary cooling is divided into two paths, one of which enters the first regeneration packing layer of the regeneration tower, and the other of which enters the second regenerator for secondary cooling; the clean water after secondary cooling is divided into two paths, one of which enters the second regeneration packing layer of the regeneration tower, and the other of which enters the third regeneration packing layer of the regeneration tower after being cooled by the cooler;

[0013] The first regeneration packing layer and the third absorption packing layer are filled with the packing with a specific surface area of 50 m 2 / m 3 -100 m 2 / m 3 The third regeneration packing layer and the first absorption packing layer are filled with the packing with a specific surface area of 310 m 2 / m 3 -400 m 2 / m 3 The second regeneration packing layer and the second absorption packing layer are filled with the packing with a specific surface area of 100 m 2 / m 3 -300 m 2 / m 3 .

[0014] In an optional embodiment, the steam heater is in communication with the separation tank, and the liquid output from the separation tank is input into the third absorption packing layer of the absorption tower;

[0015] Part of the waste water output from the bottom of the absorption tower enters the concentrated water storage tank, and then generates secondary steam after passing through the evaporation and crystallization unit;

[0016] The gas output from the separation tank, the secondary steam, and the water-containing air output from the top of the absorption tower all enter the bottom of the gas washing tower, and the bottom of the gas washing tower is connected with a circulation pipeline to circulate the liquid stored at the bottom of the gas washing tower to the top of the gas washing tower, which is sprayed and contacted with the packing in the gas washing tower, and the water-containing air output from the top of the gas washing tower enters the bottom of the regeneration tower.

[0017] In an optional embodiment, the packing on the first regeneration packing layer and the third absorption packing layer is hexagonal grid packing;

[0018] and / or, the packing on the third regeneration packing layer and the first absorption packing layer is random packing;

[0019] And / or, the filler on the second regenerative filler layer and the second absorption filler layer is corrugated hole plate filler;

[0020] And / or, the filler in the gas washing tower is grid plate.

[0021] In an optional embodiment, the top of the regeneration tower is provided with a first mist eliminator, and the top of the gas washing tower is provided with a second mist eliminator;

[0022] And / or, the first absorption filler layer, the second absorption filler layer, and the third absorption filler layer are all used to spray wastewater from the top into the filler to contact with air;

[0023] And / or, the first regenerative filler layer, the second regenerative filler layer, and the third regenerative filler layer are all used to spray clean water from the top into the filler to contact with water-containing air.

[0024] In an optional embodiment, a preheater is further included, and part of the clean water output from the bottom of the regeneration tower enters the preheater to exchange heat with desulfurization wastewater, the cooled clean water is output, and the heated wastewater enters the second absorption filler layer.

[0025] In an optional embodiment, a gas lifting device is arranged between the second regenerative filler layer and the first regenerative filler layer of the regeneration tower;

[0026] The bottom of the second regenerative filler layer is connected with a water conveying pipeline, so as to convey the clean water at the bottom of the second regenerative filler layer to the first regenerative filler layer through the water conveying pipeline.

[0027] In a second aspect, the present application provides an open gradient absorption generated wastewater purification method, which is processed by using the open gradient absorption generated wastewater purification system in any of the foregoing embodiments, and includes the following steps: heat and mass transfer of wastewater and air in an absorption tower, so that water in the wastewater enters the air, and water-containing air is output at the top of the absorption tower;

[0028] Heat and mass transfer of the water-containing air and clean water in a regeneration tower, so that water in the water-containing air enters the clean water, and air is output at the top of the regeneration tower and recycled to the bottom of the absorption tower;

[0029] In the double-stage heat recovery module formed by the first heat recovery device and the second heat recovery device, the clean water and the wastewater are heat exchanged, part of the wastewater output from the bottom of the absorption tower enters the second heat recovery device to be heated once, the wastewater heated once is divided into two paths, one path enters the first absorption filler layer of the absorption tower, and the other path enters the first heat recovery device to be heated twice; the wastewater heated twice is divided into two paths, one path enters the second absorption filler layer after being heated by the continuous drainage heater, and the other path enters the third absorption filler layer after being heated by the steam heater;

[0030] Part of the purified water output from the bottom of the regeneration tower enters the first regenerator for primary temperature reduction, and the purified water after primary temperature reduction is divided into two paths, one of which enters the first regeneration packing layer of the regeneration tower, and the other enters the second regenerator for secondary temperature reduction; the purified water after secondary temperature reduction is divided into two paths, one of which enters the second regeneration packing layer of the regeneration tower, and the other enters the third regeneration packing layer of the regeneration tower after being cooled by the cooler.

[0031] In an optional embodiment, the air feed temperature at the bottom of the absorption tower is 43-48 DEG C, the air discharge temperature at the top of the absorption tower is 85-90 DEG C, and the temperature reaches 88-92 DEG C after being treated by the washing tower and entering the regeneration tower, and the air discharge temperature at the top of the regeneration tower is 43-48 DEG C.

[0032] In an optional embodiment, the air feed temperature at the bottom of the absorption tower is 43-48 DEG C, the air discharge temperature at the top of the absorption tower is 85-90 DEG C, and the temperature reaches 88-92 DEG C after being treated by the washing tower and entering the regeneration tower, and the air discharge temperature at the top of the regeneration tower is 43-48 DEG C.

[0033] In an optional embodiment, the air feed temperature at the bottom of the absorption tower is 43-48 DEG C, the air discharge temperature at the top of the absorption tower is 85-90 DEG C, and the temperature reaches 88-92 DEG C after being treated by the washing tower and entering the regeneration tower, and the air discharge temperature at the top of the regeneration tower is 43-48 DEG C.

[0034] In an optional embodiment, the air feed temperature at the bottom of the absorption tower is 43-48 DEG C, the air discharge temperature at the top of the absorption tower is 85-90 DEG C, and the temperature reaches 88-92 DEG C after being treated by the washing tower and entering the regeneration tower, and the air discharge temperature at the top of the regeneration tower is 43-48 DEG C.

[0035] In an optional embodiment, the air feed temperature at the bottom of the absorption tower is 43-48 DEG C, the air discharge temperature at the top of the absorption tower is 85-90 DEG C, and the temperature reaches 88-92 DEG C after being treated by the washing tower and entering the regeneration tower, and the air discharge temperature at the top of the regeneration tower is 43-48 DEG C.

[0036] In an optional embodiment, the temperature of the desulfurization wastewater after being preheated by the preheater is 78-82 DEG C.

[0037] In an optional embodiment, the temperature of the desulfurization wastewater after being preheated by the preheater is 78-82 DEG C.

[0038] The present application has the following beneficial effects: the present application divides the absorption tower and the regeneration tower into three stages, utilizes the double-stage regenerator module to cooperate with the continuous drainage heater and the steam heater to realize three-stage feed temperature control of the wastewater, utilizes the double-stage regenerator module to cooperate with the cooler to realize three-stage feed temperature control of the purified water, optimizes the packing at each stage, adopts high-efficiency packing in the low-temperature and low-speed area and high-strength packing in the high-temperature and high-speed area, realizes a more optimal solution of the overall resistance, efficiency and safety, and can significantly improve the overall heat and mass transfer efficiency.

[0039] In the preferred embodiment, by rationally utilizing the separator and the washing tower, the risk of pipeline cavitation that may occur in high altitude areas or unstable heat sources is avoided. The improvement of the system is more suitable for conditions that are sensitive to heat transfer efficiency (such as limited space, which must reduce the equipment), and is also more suitable for high altitude areas or unstable heat sources. In some power plant desulfurization wastewater zero discharge conditions, the system can be preferentially selected. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0041] Figure 1 The structural diagram of the open gradient absorption wastewater purification system provided by the present application is shown in the figure.

[0042] Figure 2 The structural diagram of the open gradient absorption wastewater purification system provided by the present application is shown in the figure. Figure 1 The structural diagram of the open gradient absorption wastewater purification system provided by the present application is shown in the figure.

[0043] Figure 3 The structural diagram of the open gradient absorption wastewater purification system provided by the present application is shown in the figure.

[0044] Figure 4 The structural diagram of the open gradient absorption wastewater purification system provided by the present application is shown in the figure. Figure 3 The structural diagram of the open gradient absorption wastewater purification system provided by the present application is shown in the figure.

[0045] Main component symbol explanation: 110-absorption tower; 111-first absorption packing layer; 112-second absorption packing layer; 113-third absorption packing layer; 120-regeneration tower; 121-first regeneration packing layer; 122-second regeneration packing layer; 123-third regeneration packing layer; 124-first mist eliminator; 125-gas lifting device; 126-water conveying pipeline; 130-double stage regenerative module; 131-first regenerator; 132-second regenerator; 141-continuous drainage heater; 142-steam heater; 143-cooler; 144-separation tank; 145-concentrated water storage tank; 146-evaporation crystallization unit; 150-gas washing tower; 151-second mist eliminator; 160-preheater. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely. The specific conditions in the embodiments are not specified, and are carried out according to conventional conditions or manufacturer's recommended conditions. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased on the market.

[0047] As Figure 1 and Figure 2 shown, the embodiment of the present application provides an open type gradient absorption waste water purification system, which comprises an absorption tower 110, a regeneration tower 120 and a two-stage regenerative module 130. The absorption tower 110 and the regeneration tower 120 are designed with three-stage gradient layout in the tower. The two-stage regenerative module 130 cooperates with other heating and cooling devices to realize temperature control of each stage, and cooperates with the improvement of each stage of the filler, so as to realize the simultaneous optimization of overall resistance, efficiency and safety.

[0048] The absorption tower 110 is used for heat and mass transfer of high-temperature waste water and air. The circulating air enters from the bottom and is in countercurrent contact with the high-temperature waste water, so that the water in the high-temperature waste water enters the air. The high-temperature and high-humidity air is output from the top of the tower. The regeneration tower 120 is used for heat and mass transfer of the water-containing air generated by the absorption tower 110 and the clean water. The water-containing air enters from the bottom of the regeneration tower 120 and is in countercurrent contact with the low-temperature clean water, so that the water in the water-containing air enters the clean water. The low-temperature and low-humidity air output from the regeneration tower 120 is circulated to the absorption tower 110.

[0049] The absorption tower 110 is sequentially provided with a first absorption filler layer 111, a second absorption filler layer 112 and a third absorption filler layer 113 from bottom to top, forming a three-stage temperature gradient. The temperature of the waste water introduced from the first absorption filler layer 111 at the bottom to the third absorption filler layer 113 at the top gradually increases. Similarly, the regeneration tower 120 is sequentially provided with a first regeneration filler layer 121, a second regeneration filler layer 122 and a third regeneration filler layer 123 from bottom to top, also forming a three-stage temperature gradient. The temperature of the clean water introduced from the first regeneration filler layer 121 at the bottom to the third regeneration filler layer 123 at the top gradually decreases. The first absorption filler layer 111, the second absorption filler layer 112 and the third absorption filler layer 113 are all used for the waste water to be sprayed from the top and then fall into the filler to contact with the air. The first regeneration filler layer 121, the second regeneration filler layer 122 and the third regeneration filler layer 123 are all used for the clean water to be sprayed from the top and then fall into the filler to contact with the water-containing air.

[0050] Further, the first regeneration filler layer 121 and the third absorption filler layer 113 are filled with fillers with a specific surface area of 50m 2 / m 3 -100m 2 / m 3 , i.e. filler A1 and filler B3. The specific surface area can be 50m 2 / m 3 , 60m 2 / m 3 , 70m 2 / m 3 , 80m 2 / m 3, 90m 2 / m 3 , 95m 2 / m 3 , 100m 2 / m 3 , etc. The first regenerative packing layer 121 and the third absorption packing layer 113 are faced with large air flow (high temperature and high humidity), high flow rate, and high temperature, and preferably use hexagonal grid packing with specific surface area < 100m 2 / m 3 . This type of packing has the advantages of small resistance factor, high strength of the same material, and less softening at high temperature; the disadvantage is low specific surface area and poor mass transfer capacity. The hexagonal grid packing with specific surface area < 100m 2 / m 3 is more suitable for application to the first regenerative packing layer 121 and the third absorption packing layer 113.

[0051] Further, the third regenerative packing layer 123 and the first absorption packing layer 111 are filled with packing with specific surface area 310m 2 / m 3 - 400m 2 / m 3 (i.e. packing A3, packing B1), and the specific surface area can be 310m 2 / m 3 , 320m 2 / m 3 , 330m 2 / m 3 , 340m 2 / m 3 , 350m 2 / m 3 , 360m 2 / m 3 , 370m 2 / m 3 , 380m 2 / m 3 , 390m 2 / m 3 , 400m 2 / m 3 , etc. The third regenerative packing layer 123 and the first absorption packing layer 111 are in a low temperature and low humidity range, and the air flow rate is low, and preferably use bulk packing with specific surface area greater than 300m 2 / m 3 . This type of packing has the advantages of strong mass transfer capacity, and the disadvantage is small resistance factor and poor high temperature resistance, and this type of packing is more suitable for low temperature and low humidity sections.

[0052] Further, the second regenerative filler layer 122 and the second absorption filler layer 112 are filled with fillers with a specific surface area of 100 m 2 / m 3 - 300 m 2 / m 3 , and the specific surface area can be 100 m 2 / m 3 , 130 m 2 / m 3 , 150 m 2 / m 3 , 180 m 2 / m 3 , 200 m 2 / m 3 , 230 m 2 / m 3 , 250 m 2 / m 3 , 280 m 2 / m 3 , 300 m 2 / m 3 , etc. The second regenerative filler layer 122 and the second absorption filler layer 112 face a medium flue gas flow and temperature, and preferably use corrugated hole plate fillers with a specific surface area of 100 m 2 / m 3 - 300 m 2 / m 3 , which have medium strength, mass transfer capacity and resistance, and are suitable for being placed in the middle layer of the tower.

[0053] It should be noted that the two-stage heat recovery module 130 cooperates with other heating and cooling devices to realize temperature regulation of each stage, and cooperates with each stage of filler improvement, so that the overall resistance is low, and high specific surface area fillers are used as much as possible to increase the system processing capacity, and the tower diameter can be reduced in the design stage to reduce the system floor area.

[0054] Please refer to Figure 3 and Figure 4 , the two-stage heat recovery module 130 includes a first heat exchanger 131 and a second heat exchanger 132, and the first heat exchanger 131 and the second heat exchanger 132 are used for heat exchange between clean water and waste water to output clean water and waste water with different temperatures. The two-stage heat recovery module 130 is essentially two heat exchangers in series, and each of the two heat exchangers takes one way of waste water / clean water in the middle of the two heat exchange to spray at the bottom of the corresponding tower. By using the two-stage heat recovery module 130, part of the solution between the two heat recovery stages is used to spray the gas for the first time, so that the heat path of the heat recovery heat exchange is shorter, and a temperature gradient difference can be generated, which is beneficial to the full use of the filler.

[0055] Specifically, part of the wastewater output from the bottom of the absorption tower 110 enters the second regenerator 132 for primary heating, and the wastewater after primary heating is divided into two paths, one of which enters the first absorption packing layer 111 (i.e., the bottom spray layer of the absorption tower) of the absorption tower 110, and the other of which enters the first regenerator 131 for secondary heating; the wastewater after secondary heating is divided into two paths, one of which enters the second absorption packing layer 112 after being heated by the continuous drainage heater 141, and the other of which enters the third absorption packing layer 113 after being heated by the steam heater 142. By utilizing the temperature difference between the continuous drainage heater 141 and the steam heater 142, the temperature difference of the heated wastewater is obvious, which meets the temperature difference requirements of the second absorption packing layer 112 and the third absorption packing layer 113, and also completes the concentrated water circulation. By adopting a multi-stage gradient spray design, the boiler continuous drainage and steam are used as heat sources to heat the different air temperatures and the corresponding concentrated water or clean water, so as to shorten the heat path and make the packing fully utilized.

[0056] Specifically, the continuous drainage heater is a device for heating sewage by using the continuous drainage after the boiler continuous drainage expander, and the boiler continuous drainage will be directly discharged after passing through the expander. Therefore, the device can realize waste heat recovery of the continuous drainage. The steam heater is a device using water vapor as a heat source, which uses external steam as a heat source to produce steam condensate after cooling.

[0057] Further, part of the clean water output from the bottom of the regeneration tower 120 enters the first regenerator 131 for primary cooling, and the clean water after primary cooling is divided into two paths, one of which enters the first regeneration packing layer 121 (i.e., the bottom spray layer of the regeneration tower) of the regeneration tower 120, and the other of which enters the second regenerator 132 for secondary cooling; the clean water after secondary cooling is divided into two paths, one of which enters the second regeneration packing layer 122 (i.e., the middle spray layer of the regeneration tower) of the regeneration tower 120, and the other of which enters the third regeneration packing layer 123 of the regeneration tower 120 after being cooled by the cooler 143. In this way, the clean water entering the regeneration tower 120 is divided into three levels, which meets the temperature gradient requirements of the three spray layers and also completes the clean water circulation. Specifically, the cold source of the cooler can be low-temperature desalted water, but is not limited thereto.

[0058] In some embodiments, the steam heater 142 communicates with the separation tank 144, the wastewater after being heated by the steam heater 142 enters the separation tank for gas-liquid separation, the liquid phase after separation enters the third absorption packing layer 113 of the absorption tower, and a small amount of flash steam generated after separation enters the bottom of the gas washing tower 150. The separation tank 144 can effectively prevent pipeline cavitation after the concentrated water is heated to a high temperature, avoiding the risk of pipeline cavitation that may occur in high-altitude areas or unstable heat sources. Moreover, the steam generated by local vaporization can be directly discharged into the circulating air without passing through the concentrated water evaporation process of the absorption tower, and a part of the packing can also be saved.

[0059] Part of the wastewater output from the bottom of the absorption tower 110 enters the concentrated water storage tank 145, and then evaporates and crystallizes in the evaporation and crystallization unit 146 to produce salt, secondary steam, and steam condensate. The gas output from the separation tank 144, the secondary steam produced by the evaporation and crystallization unit 146, and the water-containing air output from the top of the absorption tower 110 all enter the bottom of the gas washing tower 150, which is connected to a circulation pipeline to circulate the liquid at the bottom of the gas washing tower 150 to the top, contact the packing in the gas washing tower 150 after spraying, and the water-containing air output from the top of the gas washing tower 150 enters the bottom of the regeneration tower 120. The gas washing tower 150 is continuously operated, and the water at the bottom is continuously pumped to the top for spraying, but no heat exchange is involved, so very little liquid water is newly produced, and the total volume of water inside the gas washing tower only increases with the continuous increase of small droplets collected during the washing process. The arrow from the gas washing tower to the absorption tower 110 indicates that when the water quality in the gas washing tower 150 is poor, the water will be discharged to the sewage tower, and this process is intermittent. Since the gas washing tower 150 has no obvious heat exchange requirement, the packing can be a grid plate, which mainly has a flow regulating effect on the gas and liquid.

[0060] It should be noted that the secondary steam produced by the evaporation and crystallization process and the partial vaporization steam produced by heating the concentrated water to a higher temperature by steam are added to the gas washing tower 150, which can wash the water vapor and remove the liquid on one hand, and the three gases can be combined in the tower to ensure stable operation without pipeline vibration and save a steam drum.

[0061] In some embodiments, the top of the regeneration tower 120 is provided with a first mist eliminator 124, and the top of the gas washing tower 150 is provided with a second mist eliminator 151, which can effectively separate the liquid droplets or mist entrained in the gas.

[0062] In some embodiments, the open gradient absorption wastewater purification system further comprises a preheater 160. Part of the purified water output from the bottom of the regeneration tower 120 enters the preheater 160 to exchange heat with the desulfurization wastewater, and the cooled purified water is output. The heated wastewater enters the second absorption packing layer 112 and is in countercurrent contact with the air. By preheating the wastewater and cooling the purified water, the heat is fully utilized, and the temperature of the heated wastewater is not much different from the temperature range of the second absorption packing layer 112, so it can be directly introduced into the second absorption packing layer 112.

[0063] Further, the air-lift device 125 is arranged between the second regeneration packing layer 122 and the first regeneration packing layer 121 of the regeneration tower 120. That is, the air-lift device 125 is arranged at the bottom of the second regeneration packing layer 122, and can prevent the clean water in the second regeneration packing layer 122 from directly falling into the first regeneration packing layer 121. The air-lift device 125 is arranged above the spraying layer corresponding to the first regeneration packing layer 121, and the purpose is to intercept the falling of the upper liquid, so that the water flow is less in the lower section of the regeneration tower with large air flow, and the liquid flooding phenomenon of the packing can be effectively prevented. Meanwhile, the tower diameter can be made smaller, which is beneficial to saving the equipment cost. The bottom of the second regeneration packing layer 122 is connected with a water conveying pipeline 126, and the clean water at the bottom of the second regeneration packing layer 122 can be conveyed to the first regeneration packing layer 121 through the water conveying pipeline 126, and the liquid in the lower part of the second regeneration packing layer 122 can be continuously discharged to the first regeneration packing layer 121.

[0064] The embodiment of the present application also provides an open gradient absorption method for generating clean water, which comprises: heat and mass transfer of the waste water and air in the absorption tower 110, so that the water in the waste water enters the air, and the air containing water is output at the top of the absorption tower 110; heat and mass transfer of the air containing water and clean water in the regeneration tower 120, so that the water in the air containing water enters the clean water, and the air is output at the top of the regeneration tower 120 and recycled to the bottom of the absorption tower 110.

[0065] The double-stage heat recovery module 130 formed by the first heat recovery device 131 and the second heat recovery device 132 exchanges heat with the clean water and the waste water, part of the waste water output at the bottom of the absorption tower 110 enters the second heat recovery device 132 for primary heating, and the waste water after the primary heating is divided into two paths, one of which enters the first absorption packing layer 111 of the absorption tower 110, and the other of which enters the first heat recovery device 131 for secondary heating; the waste water after the secondary heating is divided into two paths, one of which enters the second absorption packing layer 112 after being heated by the continuous discharge water heater 141, and the other of which enters the third absorption packing layer 113 after being heated by the steam heater 142.

[0066] Part of the clean water output at the bottom of the regeneration tower 120 enters the first heat recovery device 131 for primary cooling, and the clean water after the primary cooling is divided into two paths, one of which enters the first regeneration packing layer 121 of the regeneration tower 120, and the other of which enters the second heat recovery device 132 for secondary cooling; the clean water after the secondary cooling is divided into two paths, one of which enters the second regeneration packing layer 122 of the regeneration tower 120, and the other of which enters the third regeneration packing layer 123 of the regeneration tower 120 after being cooled by the cooler 143.

[0067] It should be noted that the two-stage regenerative module is used to cooperate with the continuous drainage heater and the steam heater to realize the three-stage feed temperature control of the wastewater, the two-stage regenerative module is used to cooperate with the cooler to realize the three-stage feed temperature control of the clean water, and meanwhile, the fillers of each stage are optimized, the high-efficiency filler is used in the low-temperature and low-speed area, and the high-strength filler is used in the high-temperature and high-speed area, so that a more optimal solution of the overall resistance, efficiency and safety is realized, and the overall heat and mass transfer efficiency can be significantly improved.

[0068] Figure 1 The working principles of other structures are not repeated here, and the operation parameters of each link are optimized by the inventors to further improve the heat and mass transfer efficiency.

[0069] The air feed temperature at the bottom of the absorption tower 110 is 43-48℃, the air discharge temperature at the top of the absorption tower 110 is 85-90℃, and after being treated by the washing tower 150, the temperature reaches 88-92℃ and enters the regeneration tower 120, and the air discharge temperature at the top of the regeneration tower 120 is 43-48℃. It is appropriate to control the temperature of the air in each link within the above range to improve the wastewater treatment effect.

[0070] Further, the clean water feed temperature of the first regeneration filler layer 121 of the regeneration tower 120 is 65-70℃, the clean water feed temperature of the second regeneration filler layer 122 is 55-60℃, and the clean water feed temperature of the third regeneration filler layer 123 is 35-40℃. The temperature of the wastewater output from the bottom of the absorption tower 110 is 48-52℃, and the temperature of the clean water output from the bottom of the regeneration tower 120 is 82-88℃. The wastewater feed temperature of the first absorption filler layer 111 of the absorption tower 110 is 63-67℃, the wastewater feed temperature of the second absorption filler layer 112 is 88-92℃, and the wastewater feed temperature of the third absorption filler layer 113 is 93-98℃. By adjusting the three-stage operation temperature of the absorption tower 110 and the regeneration tower 120, the heat and mass transfer effect can be improved, the water in the wastewater can be fully recovered into the clean water, and the wastewater zero discharge can be realized.

[0071] Further, the temperature of the desulfurization wastewater after being preheated by the preheater 160 is 78-82℃, which is close to the temperature of the second absorption filler layer. The temperature of the wastewater entering the continuous drainage heater 141 and the steam heater 142 is 78-82℃, that is, the temperature of the wastewater after being treated by the two regenerators in the two-stage regenerative module meets the above requirements, and after being further heated by the continuous drainage heater 141 and the steam heater 142, the temperature meets the temperature requirements of the second absorption filler layer 112 and the third absorption filler layer 113.

[0072] The features and performance of the present application are further described in detail below in combination with embodiments.

[0073] Example 1

[0074] The embodiment provides an open gradient absorption wastewater purification method Figures 1-4 The specific steps and parameters of each link are as follows:

[0075] The desulfurization wastewater at 40 DEG C is input into the preheater at a flow rate of 3t / h, exchanges heat with the output purified water (85 DEG C) at the bottom of the regeneration tower 120, the purified water is cooled to 42 DEG C, and is output at a flow rate of 2.7t / h; the wastewater is increased to 80 DEG C and input into the second absorption filler layer 112 of the absorption tower 110.

[0076] The air at 45 DEG C and 2400 standard cubic meters / h is input into the bottom of the absorption tower 110, sequentially passes through the first absorption filler layer 111, the second absorption filler layer 112 and the third absorption filler layer 113, and then is output from the top of the tower as high-temperature and high-humidity air (temperature is 88 DEG C), is input into the gas washing tower 150, and is output from the gas washing tower 150 at a temperature of 90 DEG C. Then, the air is input into the bottom of the regeneration tower 120 at a flow rate of 5800 standard cubic meters / h, sequentially passes through the first regeneration filler layer 121, the second regeneration filler layer 122 and the third regeneration filler layer 123, is output from the top of the tower at a temperature of 45 DEG C, and is recycled to the bottom of the absorption tower 110.

[0077] Part of the wastewater (50 DEG C, 60t / h) output from the bottom of the absorption tower 110 is input into the second regenerator 132 to be heated once, the wastewater after being heated once is divided into two paths, one path (the temperature of the wastewater is 65 DEG C, and the flow rate is 20t / h) is input into the first absorption filler layer 111 of the absorption tower 110, and the other path (the temperature of the wastewater is 65 DEG C, and the flow rate is 40t / h) is input into the first regenerator 131 to be heated twice; the wastewater after being heated twice is divided into two paths, one path (the flow rate is 20t / h) is heated to 90 DEG C by the continuous drainage heater 141 and then is input into the second absorption filler layer 112, and the other path (the flow rate is 20t / h) is heated to 95 DEG C by the steam heater 142 and then is input into the third absorption filler layer 113.

[0078] Part of the purified water (85 DEG C, 75t / h) output from the bottom of the regeneration tower 120 is input into the first regenerator 131 to be cooled once, the purified water after being cooled once is divided into two paths, one path (the temperature of the purified water is 77 DEG C, and the flow rate is 25t / h) is input into the first regeneration filler layer 121 of the regeneration tower 120, and the other path is input into the second regenerator 132 to be cooled twice; the purified water after being cooled twice is divided into two paths, one path (the flow rate is 25t / h) is input into the second regeneration filler layer 122 of the regeneration tower 120, and the other path (the flow rate is 25t / h) is cooled to 38 DEG C by the cooler 143 and then is input into the third regeneration filler layer 123 of the regeneration tower 120.

[0079] The continuous drainage heater 141 enters 145℃ continuous drainage with a flow rate of 4t / h, and the continuous drainage outlet temperature is 90℃. The steam flow rate entering the steam heater 142 is 0.6t / h, and 0.6t / h steam condensate is generated. After the waste water heated by the steam heater 142 is separated by the separation tank 144, 0.1t / h exhaust steam enters the gas washing tower 150. The desalination make-up water entering the cooler 143 has a flow rate of 50t / h and a temperature of 35℃, and the make-up water temperature after exiting the cooler 143 is 50℃.

[0080] The concentrated water with a temperature of 50℃ output from the absorption tower 110 enters the concentrated water storage tank 145 with a flow rate of 0.3t / h, and then evaporates and crystallizes in the evaporation crystallization unit 146 to generate salt (0.1t / h), secondary steam (0.2t / h) and steam condensate (0.2t / h), and the steam flow rate entering the evaporation crystallization unit 146 is 0.2t / h.

[0081] The packing A1 and the packing B3 adopt hexagonal grid packing with a specific surface area of 80m 2 / m 3 , the material is reinforced PP, and the packing height is 1 meter; the packing A2 and the packing B2 adopt 125X corrugated hole plate packing with a specific surface area of 125m 2 / m 3 , the material is reinforced PP, and the packing height is 1 meter; the packing A3 and the packing B1 adopt multi-faceted hollow sphere random packing with a specific surface area of 400m 2 / m 3 , the material is PP, and the packing height is 1 meter. The washing tower packing C adopts hexagonal grid packing with a specific surface area of 80m 2 / m 3 , the material is reinforced PP, and the packing height is 0.4 meters.

[0082] The embodiment finally can utilize 0.8t / h steam (steam heater 142 and evaporation crystallization unit 146) to realize 3t / h desulfurization waste water zero emission, generate 0.1t / h salt and 2.9t / h clean water, and the tower diameter is 1.2 meters.

[0083] The above only is the preferred embodiment of the present application, and does not limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An open gradient absorption waste water purification system characterized by, The application relates to a wastewater absorption and regeneration system. The system comprises: an absorption tower for heat and mass transfer between wastewater and air, so that water in the wastewater enters the air, and water-containing air is output; the absorption tower is sequentially provided with a first absorption filler layer, a second absorption filler layer and a third absorption filler layer from bottom to top; a regeneration tower for heat and mass transfer between the water-containing air generated by the absorption tower and clean water, so that water in the water-containing air enters the clean water, and air output by the regeneration tower is circulated to the absorption tower; the regeneration tower is sequentially provided with a first regeneration filler layer, a second regeneration filler layer and a third regeneration filler layer from bottom to top; a double-stage heat recovery module, which comprises a first heat recovery device and a second heat recovery device; the first heat recovery device and the second heat recovery device are both used for heat exchange between clean water and wastewater; part of the wastewater output from the bottom of the absorption tower enters the second heat recovery device for primary heating, the wastewater after primary heating is divided into two paths, one path enters the first absorption filler layer of the absorption tower, and the other path enters the first heat recovery device for secondary heating; the wastewater after secondary heating is divided into two paths, one path enters the second absorption filler layer after being heated by a continuous drainage heater, and the other path enters the third absorption filler layer after being heated by a steam heater; said first regenerative filler bed and said third absorbent filler bed are loaded with a filler having a specific surface area comprised between 50 m 2 / m 3 -100 m 2 / m 3 , said third regenerative filler bed and said first absorbent filler bed are loaded with a filler having a specific surface area comprised between 310 m 2 / m 3 -400 m 2 / m 3 , said second regenerative filler bed and said second absorbent filler bed are loaded with a filler having a specific surface area comprised between 100 m 2 / m 3 -300 m 2 / m 3 . part of the clean water output from the bottom of the regeneration tower enters the first heat recovery device for primary cooling, the clean water after primary cooling is divided into two paths, one path enters the first regeneration filler layer of the regeneration tower, and the other path enters the second heat recovery device for secondary cooling; the clean water after secondary cooling is divided into two paths, one path enters the second regeneration filler layer of the regeneration tower, and the other path enters the third regeneration filler layer of the regeneration tower after being cooled by a cooler; the steam heater is communicated with a separation tank, and liquid output by the separation tank is input into the third absorption filler layer of the absorption tower; part of the wastewater output from the bottom of the absorption tower enters a concentrated water storage tank, and then generates secondary steam after passing through an evaporation and crystallization unit; gas output by the separation tank, the secondary steam and water-containing air output from the top of the absorption tower all enter the bottom of a gas washing tower, the bottom of the gas washing tower is connected with a circulating pipeline, so that liquid stored at the bottom of the gas washing tower is circulated to the top of the gas washing tower through the circulating pipeline, and then is sprayed and contacted with fillers in the gas washing tower, and water-containing air output from the top of the gas washing tower enters the bottom of the regeneration tower; 2. The open gradient absorption waste water purification system as claimed in claim 1, wherein, the fillers on the first regeneration filler layer and the third absorption filler layer are hexagonal grid fillers; the fillers on the third regeneration filler layer and the first absorption filler layer are random pile fillers; the fillers on the second regeneration filler layer and the second absorption filler layer are corrugated hole plate fillers; and the fillers in the gas washing tower are grid plates. a first demister is arranged at the top of the regeneration tower, and a second demister is arranged at the top of the gas washing tower; and / or, the first absorption filler layer, the second absorption filler layer and the third absorption filler layer are all used for spraying wastewater from the top and then falling into the fillers to be contacted with air; and / or, the first regeneration filler layer, the second regeneration filler layer and the third regeneration filler layer are all used for spraying clean water from the top and then falling into the fillers to be contacted with water-containing air.

3. The open gradient absorption waste water purification system as claimed in claim 1, wherein, Further comprising a preheater, part of the purified water output from the bottom of the regeneration tower enters the preheater to exchange heat with desulfurization wastewater, the cooled purified water is output, and the heated wastewater enters the second absorption packing layer.

4. The open gradient absorption waste water purification system as claimed in claim 1, wherein, An air lift device is arranged between the second regeneration packing layer and the first regeneration packing layer of the regeneration tower; The bottom of the second regeneration packing layer is connected with a water conveying pipeline, so that the purified water at the bottom of the second regeneration packing layer is conveyed to the first regeneration packing layer through the water conveying pipeline.

5. An open gradient absorption generating wastewater purification method characterized by, The open gradient absorption system of any one of claims 1-4 is used for wastewater treatment, including: heat and mass transfer of wastewater and air in the absorption tower, so that water in the wastewater enters the air, and water-containing air is output at the top of the absorption tower; The water-containing air exchanges heat and mass with purified water in the regeneration tower, so that water in the water-containing air enters the purified water, and air is output at the top of the regeneration tower and recycled to the bottom of the absorption tower; The double-stage heat recovery module formed by the first heat recovery device and the second heat recovery device exchanges heat with the purified water and the wastewater, part of the wastewater output from the bottom of the absorption tower enters the second heat recovery device for primary heating, the once-heated wastewater is divided into two paths, one path enters the first absorption packing layer of the absorption tower, and the other path enters the first heat recovery device for secondary heating; the twice-heated wastewater is divided into two paths, one path enters the second absorption packing layer after being heated by the continuous drainage heater, and the other path enters the third absorption packing layer after being heated by the steam heater; Part of the purified water output from the bottom of the regeneration tower enters the first heat recovery device for primary cooling, the once-cooled purified water is divided into two paths, one path enters the first regeneration packing layer of the regeneration tower, and the other path enters the second heat recovery device for secondary cooling; the twice-cooled purified water is divided into two paths, one path enters the second regeneration packing layer of the regeneration tower, and the other path enters the third regeneration packing layer of the regeneration tower after being cooled by the cooler.

6. The open gradient absorption waste water purification method according to claim 5, wherein The air feed temperature at the bottom of the absorption tower is 43-48℃, the air discharge temperature at the top of the absorption tower is 85-90℃, and the temperature reaches 88-92℃ after being treated by the washing tower and entering the regeneration tower, and the air discharge temperature at the top of the regeneration tower is 43-48℃; And / or, the temperature of the wastewater output from the bottom of the absorption tower is 48-52℃; And / or, the temperature of the purified water output from the bottom of the regeneration tower is 82-88℃.

7. The open gradient absorption waste water purification method according to claim 6, wherein The purified water feed temperature of the first regeneration packing layer of the regeneration tower is 65-70℃, the purified water feed temperature of the second regeneration packing layer is 55-60℃, and the purified water feed temperature of the third regeneration packing layer is 35-40℃; And / or, the wastewater feed temperature of the first absorption packing layer of the absorption tower is 63-67℃, the wastewater feed temperature of the second absorption packing layer is 88-92℃, and the wastewater feed temperature of the third absorption packing layer is 93-98℃.

8. The open gradient absorption waste water purification method according to claim 6, wherein, The temperature of the desulfurization wastewater after being preheated by the preheater is 78-82℃; And / or, the temperature of the waste water entering the in-line waste water heater and the steam heater is 78-82°C.

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