A high-salt and high-COD wastewater treatment system and method

Abstract

The present invention relates to the technical field of wastewater treatment, and provides a high-salt and high-COD wastewater treatment system and method. The system provided by the present invention includes a wastewater dryer, a waste salt incinerator, a molten salt collection tank, a gas insulation shell, a heat exchanger, a cyclone dust collector and an exhaust gas processor. The system provided by the present invention uses a wastewater dryer to dry high-salt and high-COD wastewater, and the waste salt mixture is passed into the waste salt incinerator for incineration. During the incineration process, organic matter is completely decomposed, and the salts become molten and enter the molten salt collection tank. The high-temperature flue gas generated by the incineration is heat-exchanged with cold air in the heat exchanger, and the high-temperature air generated enters the wastewater dryer to provide a heat source for wastewater drying, and the low-temperature flue gas enters the cyclone dust collector and the exhaust gas processor for treatment, and is discharged after obtaining clean gas. The system provided by the present invention has a simple structure and high energy utilization rate, can completely decompose organic matter and separate salts, and realize zero-emission treatment and resource utilization of high-salt and high-COD wastewater.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and in particular to a system and method for treating high-salt and high-COD wastewater. Background Art

[0002] With the acceleration of industrialization, high-salt and high-COD wastewater will be produced in many fields, such as printing and dyeing, papermaking, chemical industry, coking and other fields. In addition to high concentrations of organic matter, high-salt and high-COD wastewater also contains a large amount of inorganic salts, mainly sodium, potassium, and calcium sulfate or hydrochloride. If these wastewaters enter the soil system, soil organisms and plants will die due to dehydration, causing damage to the ecosystem. If they enter the water environment, they will cause eutrophication of the water body and cause significant pollution to the water environment.

[0003] At present, the treatment processes for high-salt and high-COD wastewater mainly include electrolysis and evaporation. The electrolysis method uses electrochemical methods to electrolyze organic matter and inorganic salts. This method is costly and it is difficult to completely decompose organic matter. The evaporation method uses heating to vaporize part of the solvent in the solution to increase the solution concentration and create conditions for the precipitation of solutes. However, this method cannot effectively remove organic matter, and the resulting solid salt is of low purity and cannot be reused.

[0004] In summary, the current wastewater treatment methods cannot achieve the complete decomposition of organic matter in high-salt and high-COD wastewater and the resource utilization of inorganic salts. The development of new high-salt and high-COD wastewater treatment technologies is imminent. Summary of the invention

[0005] The purpose of the present invention is to provide a system and method for treating high-salt and high-COD wastewater. The system provided by the present invention can completely decompose the difficult-to-treat organic matter in the wastewater and separate the salts, thereby achieving zero-discharge treatment and resource utilization of high-salt and high-COD wastewater.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A high-salt and high-COD wastewater treatment system, characterized in that it comprises a wastewater dryer 1, wherein the wastewater dryer 1 is provided with a wastewater inlet, an air inlet and a waste salt outlet;

[0008] A waste salt incinerator 2, wherein the waste salt incinerator 2 is provided with a waste salt inlet, a molten salt outlet, a combustion-supporting gas inlet and a flue gas outlet; the waste salt inlet is connected to the waste salt outlet of the wastewater dryer 1;

[0009] A molten salt collecting tank 3, the inlet of the molten salt collecting tank 3 is connected to the molten salt outlet of the waste salt incinerator 2, and the outer wall of the flue connecting the inlet of the molten salt collecting tank 3 and the molten salt outlet of the waste salt incinerator 2 and the outer wall of the molten salt collecting tank 3 are provided with a gas insulation shell 4;

[0010] A heat exchanger 5, wherein the heat exchanger 5 is provided with a smoke inlet, a smoke outlet, an air inlet and an air outlet; the smoke inlet of the heat exchanger 5 is communicated with the smoke outlet of the waste salt incinerator 2, the air inlet of the heat exchanger 5 is communicated with the blower 9, and the air outlet of the heat exchanger 5 is communicated with the air inlet of the wastewater dryer 1;

[0011] A cyclone dust collector 6, wherein the inlet of the cyclone dust collector 6 is connected to the flue gas outlet of the heat exchanger;

[0012] The exhaust gas processor 7 has an inlet connected to the outlet of the cyclone dust collector 6 .

[0013] Preferably, two branch flues are provided on the flue connecting the flue gas outlet of the waste salt incinerator 2 and the flue gas inlet of the heat exchanger 5, which are respectively denoted as a first branch flue and a second branch flue. The first branch flue is arranged on the flue gas outlet side of the waste salt incinerator 2 and is connected to the inlet of the gas insulation shell 4. The second branch flue is arranged on the flue gas inlet side of the heat exchanger 5 and is connected to the outlet of the gas insulation shell 4.

[0014] Preferably, an atomizer is provided in the wastewater dryer 1, and the atomizer is a two-phase flow nozzle atomizer or a three-phase flow nozzle atomizer.

[0015] Preferably, the waste salt incinerator 2 includes a straight section and a cone bucket arranged at the bottom of the straight section; an air curtain device 10 is arranged on the inner wall of the straight section; a branch flue is arranged on the flue connecting the air outlet of the heat exchanger 5 and the air inlet of the wastewater dryer 1, which is recorded as the third branch flue, and the third branch flue is connected to the air curtain device 10;

[0016] An electric scraper is arranged on the inner wall of the cone bucket, and an electric baffle door is arranged on the bottom of the cone bucket.

[0017] Preferably, an induced draft fan 8 is provided on the outlet flue of the cyclone dust collector 6 .

[0018] Preferably, the exhaust gas processor 7 is an activated carbon adsorption exhaust gas treatment device.

[0019] The present invention also provides a method for treating high-salt and high-COD wastewater using the system described in the above scheme, comprising the following steps:

[0020] Drying the high-salt and high-COD wastewater in a wastewater dryer 1 to obtain a waste salt mixture;

[0021] The waste salt mixture enters the waste salt incinerator 2 and is incinerated together with the combustion-supporting gas to obtain molten salt and high-temperature flue gas, and the molten salt enters the molten salt collection tank 3;

[0022] The high-temperature flue gas enters the heat exchanger 5 and exchanges heat with the cold air sent by the blower 9 to obtain low-temperature flue gas and high-temperature air; the high-temperature air enters the wastewater dryer 1 to provide a heat source for drying the wastewater;

[0023] The low-temperature flue gas enters the cyclone dust collector 6 for dust removal, and the obtained dust-removed flue gas enters the exhaust gas processor 7 for treatment, and is discharged after obtaining clean gas.

[0024] Preferably, the incineration temperature is 800-1000°C.

[0025] Preferably, the temperature of the high-temperature air is 400-600°C, and the temperature of the low-temperature flue gas is 100-150°C.

[0026] Preferably, a portion of the high-temperature flue gas enters the gas insulation shell 4 from the first branch flue, and then returns from the second branch flue and enters the heat exchanger 5.

[0027] The present invention provides a high-salt and high-COD wastewater treatment system, comprising a wastewater dryer 1, a waste salt incinerator 2, a molten salt collection tank 3, a gas insulation shell 4, a heat exchanger 5, a cyclone dust collector 6 and an exhaust gas processor 7. The system provided by the present invention uses the wastewater dryer 1 to dry the high-salt and high-COD wastewater, and then passes the generated waste salt mixture into the waste salt incinerator 2 for incineration. During the incineration process, the organic matter is completely decomposed, and the salts become molten and enter the molten salt collection tank 3. The collected molten salt is subsequently processed by salt separation to achieve resource utilization. The gas insulation shell 4 can insulate the molten salt to prevent the molten salt from cooling and crystallizing; the high-temperature flue gas generated by the incineration is heat-exchanged with the cold air in the heat exchanger 5, and the generated high-temperature air enters the wastewater dryer 1 to provide a heat source for wastewater drying, and the low-temperature flue gas enters the cyclone dust collector 6 for dust removal. The dust-removed flue gas passes through the exhaust gas processor 7 to obtain clean gas, and the clean gas can be discharged. The system provided by the present invention has a simple structure and high energy utilization rate, and can completely decompose organic matter and separate salts, thereby achieving zero-discharge treatment and resource utilization of high-salt and high-COD wastewater.

[0028] The present invention also provides a method for resource utilization of high-salt and high-COD wastewater using the system described in the above scheme. The method provided by the present invention has simple steps, is easy to operate, has high energy utilization rate, and is low in cost. It can effectively treat high-salt and high-COD wastewater and separate salts for resource utilization. At the same time, only clean gas is discharged during the whole process, achieving zero emission treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of the high-salt and high-COD wastewater treatment system of the present invention, wherein: 1-wastewater dryer, 2-waste salt incinerator, 3-molten salt collection tank, 4-gas insulation shell, 5-heat exchanger, 6-cyclone dust collector, 7-exhaust processor, 8-induced draft fan, 9-supply fan, 10-air curtain device. DETAILED DESCRIPTION

[0030] The present invention provides a high-salt and high-COD wastewater treatment system, the structural schematic diagram of which is as follows: Figure 1 As shown below, combined Figure 1 Provide specific instructions.

[0031] The system provided by the present invention includes a wastewater dryer 1. In the present invention, the wastewater dryer 1 is provided with a wastewater inlet, an air inlet and a waste salt outlet; the wastewater dryer 1 is preferably provided with an atomizer, and the atomizer is preferably a two-phase flow nozzle atomizer or a three-phase flow nozzle atomizer.

[0032] The system provided by the present invention includes a waste salt incinerator 2. In the present invention, the waste salt incinerator 2 is provided with a waste salt inlet, a molten salt outlet, a combustion-supporting gas inlet and a flue gas outlet; the waste salt inlet of the waste salt incinerator 2 is connected to the waste salt outlet of the wastewater dryer 1. In the present invention, each device is connected through a flue, which will not be described in detail later.

[0033] In the present invention, the waste salt incinerator 2 includes a straight cylinder section and a conical bucket arranged at the bottom of the straight cylinder section; the inner side of the straight cylinder section is preferably provided with an air curtain device 10 close to the wall, and the air curtain device is used to prevent the molten salt from sticking to the wall; the inner side of the conical bucket is preferably provided with an electric scraper close to the wall, and the bottom of the conical bucket is provided with an electric baffle door. In a specific embodiment of the present invention, it is preferred to start the electric scraper at a fixed time and open the electric baffle door to discharge the molten salt in the conical bucket into the molten salt collection tank.

[0034] The system provided by the present invention includes a molten salt collecting tank 3. In the present invention, the inlet of the molten salt collecting tank 3 is connected to the molten salt outlet of the waste salt incinerator 2, and the outer wall of the flue connecting the inlet of the molten salt collecting tank 3 and the molten salt outlet of the waste salt incinerator 2 and the outer wall of the molten salt collecting tank 3 are provided with a gas insulation shell 4, and the gas insulation shell 4 is used to insulate the molten salt collecting tank to prevent the molten salt from cooling and crystallizing.

[0035] The system provided by the present invention includes a heat exchanger 5. In the present invention, the heat exchanger 5 is provided with a flue gas inlet, a flue gas outlet, an air inlet and an air outlet; the flue gas inlet of the heat exchanger 5 is connected to the flue gas outlet of the waste salt incinerator 2, the air inlet of the heat exchanger 5 is connected to the blower 9, and the air outlet of the heat exchanger 5 is connected to the air inlet of the waste water dryer 1. In the present invention, the blower 9 sends cold air into the heat exchanger, and the cold air exchanges heat with the high-temperature flue gas discharged from the waste salt incinerator 2, thereby rapidly cooling the high-temperature flue gas, and the hot air generated at the same time is sent to the waste water dryer 1 to provide a heat source for drying the waste water, thereby improving the energy utilization rate of the system.

[0036] In the present invention, the flue connecting the flue gas outlet of the waste salt incinerator 2 and the flue gas inlet of the heat exchanger 5 is preferably provided with two branch flues, which are respectively recorded as the first branch flue and the second branch flue. The first branch flue is preferably arranged at the flue gas outlet side of the waste salt incinerator 2 and connected to the inlet of the gas insulation shell 4. The second branch flue is preferably arranged at the flue gas inlet side of the heat exchanger 5 and connected to the outlet of the gas insulation shell. When used, a part of the high-temperature flue gas generated in the waste salt incinerator enters the gas insulation shell 4 from the first branch flue to provide a heat source for insulation, and then returns to the heat exchanger 5 from the second branch flue.

[0037] In the present invention, a branch flue is provided on the flue connecting the air outlet of the heat exchanger 5 and the air inlet of the wastewater dryer 1, which is recorded as the third branch flue. The third branch flue is connected to the wind curtain device 10. The wind curtain device 10 extracts part of the hot air from the hot air outlet flue of the heat exchanger 5 to form a thin layer of wall-attaching wind in the waste salt incinerator 2, isolating the wall surface of the waste salt incinerator 2 from the waste salt incineration area, and preventing the molten salt from adhering to the wall and causing scaling and corrosion of the wall.

[0038] The system provided by the present invention includes a cyclone dust collector 6. In the present invention, the inlet of the cyclone dust collector 6 is connected to the flue gas outlet of the heat exchanger; the outlet flue of the cyclone dust collector is preferably provided with an induced draft fan 8. The present invention forms a negative pressure in the system by providing the induced draft fan 8 to drive the flue gas to flow toward the exhaust gas processor.

[0039] The system exhaust gas processor 7 provided by the present invention. In the present invention, the inlet of the exhaust gas processor 7 is connected to the outlet of the cyclone dust collector 6; the exhaust gas processor 7 is preferably an activated carbon adsorption exhaust gas treatment device.

[0040] The present invention also provides a method for treating high-salt and high-COD wastewater using the system described in the above scheme, comprising the following steps:

[0041] Drying the high-salt and high-COD wastewater in a wastewater dryer 1 to obtain a waste salt mixture;

[0042] The waste salt mixture enters the waste salt incinerator 2 and is incinerated together with the combustion-supporting gas to obtain molten salt and high-temperature flue gas, and the molten salt enters the molten salt collection tank 3;

[0043] The high-temperature flue gas enters the heat exchanger 5 and exchanges heat with the cold air sent in by the blower to obtain low-temperature flue gas and high-temperature air; the high-temperature air enters the wastewater dryer 1 to provide a heat source for drying the wastewater;

[0044] The low-temperature flue gas enters the cyclone dust collector 6 for dust removal, and the obtained dust-removed flue gas enters the exhaust gas processor 7 for treatment, and is discharged after obtaining clean gas.

[0045] The present invention dries the high-salt and high-COD wastewater in a wastewater dryer 1 to obtain a waste salt mixture. In the present invention, the COD content of the high-salt and high-COD wastewater is preferably 20000mg / L to 200000mg / L, more preferably 130000mg / L to 180000mg / L, and the salt content is preferably 30000mg / L to 150000mg / L, more preferably 50000mg / L to 130000mg / L; the present invention has no special requirements on the types of inorganic salts in the high-salt and high-COD wastewater, such as sodium chloride, sodium sulfate, potassium chloride, potassium sulfate, calcium chloride, etc. Specifically, the chloride ion content in the high-salt and high-COD wastewater is preferably 80 00mg / L~70000mg / L, the content of sulfate is preferably 6500mg / L~40000mg / L, the content of sodium ion is preferably 9000mg / L~88000mg / L, the content of potassium ion is preferably 4000mg / L~20000mg / L, and the content of calcium ion is preferably 2500mg / L~12000mg / L; the present invention has no special requirements on the source of the high-salt and high-COD wastewater, and the high-salt and high-COD wastewater well known to those skilled in the art can be treated using the method of the present invention, such as coking wastewater, printing and dyeing wastewater, and chemical wastewater.

[0046] In the present invention, the high-salt and high-COD wastewater is atomized and sprayed out after entering the wastewater dryer 1, and the atomized wastewater undergoes mass transfer and heat exchange with the high-temperature air from the heat exchanger 5. The water in the atomized wastewater is converted into water vapor, and the salt, organic matter and other impurities are solidified to form a waste salt mixture.

[0047] After the waste salt mixture is obtained, the waste salt mixture enters the waste salt incinerator 2 and is incinerated together with the combustion-supporting gas to obtain molten salt and high-temperature flue gas. In the present invention, the waste salt mixture is specifically carried into the waste salt incinerator 2 by high-temperature air, and no additional air supplementation is required during the incineration process; the combustion-supporting gas is preferably natural gas; the incineration temperature is preferably 800-1000°C, more preferably 850-950°C.

[0048] In a specific embodiment of the present invention, it is preferred to first introduce a combustion-supporting gas into the waste salt incinerator 2 and then ignite it to ensure that the temperature in the waste salt incinerator 2 is maintained at 800-1000°C, then turn on the blower 9 and the heat exchanger 5, stabilize the hot air temperature of the heat exchanger 5 at 400-600°C, and then introduce high-salt and high-COD wastewater into the wastewater dryer 1. After the wastewater is atomized, it exchanges heat with the high-temperature air from the heat exchanger 5, and the resulting waste salt mixture is subsequently treated.

[0049] During the incineration process, the wind curtain device 10 in the waste salt incinerator 2 extracts part of the hot air from the hot air outlet flue of the heat exchanger 5, forming a thin layer of wall-adhering wind in the waste salt incinerator 2, isolating the wall surface of the waste salt incinerator 2 from the waste salt incineration area, and preventing the molten salt from adhering to the wall and causing scaling and corrosion of the wall.

[0050] During the incineration process, the organic matter in the waste salt mixture is completely burned and decomposed, and the salts become molten and are discharged into the molten salt collection tank 3. The molten salt in the molten salt collection tank 3 accumulates and is discharged after the tank is full for salt separation treatment to achieve resource utilization. The present invention has no special requirements for the salt separation treatment method, and the method familiar to those skilled in the art can be used.

[0051] After the high-temperature flue gas is generated, the high-temperature flue gas enters the heat exchanger 5, exchanges heat with the cold air sent by the blower 9, and obtains low-temperature flue gas and high-temperature air. In the present invention, a part of the high-temperature flue gas directly enters the heat exchanger 5, and the other part enters the gas insulation shell 4 from the first branch flue, and after circulating in the gas insulation shell 4, it returns from the second branch flue and enters the heat exchanger 5. The present invention uses part of the high-temperature flue gas to provide a heat source for the gas insulation shell 4, realizes the insulation of the molten salt collection tank, avoids the cooling and crystallization of the molten salt, and at the same time improves the energy utilization rate and avoids the introduction of external heat sources.

[0052] In the present invention, the temperature of the high-temperature flue gas is preferably 800-1000°C, and the temperature of the cold air sent by the blower 9 is preferably 20-30°C; the temperature of the high-temperature air is preferably 400-600°C, more preferably 450-550°C, and the temperature of the low-temperature flue gas is preferably 100-150°C, more preferably 110-130°C. The present invention uses cold air heat exchange to quench the high-temperature flue gas to prevent the flue gas from synthesizing organic matter again after slow cooling. In the present invention, the high-temperature air enters the wastewater dryer 1 to provide a heat source for drying the wastewater.

[0053] After obtaining the low-temperature flue gas, the low-temperature flue gas enters the cyclone dust collector 6 for dust removal, and the obtained dust-removed flue gas enters the exhaust gas processor 7 for treatment, and is discharged after obtaining clean gas. In the present invention, the cyclone dust collector 6 is used to remove particulate matter carried in the low-temperature flue gas, and the exhaust gas processor 7 is used to remove NO in the flue gas after the waste salt is incinerated. x and SO x , and then discharge the clean gas.

[0054] In the above treatment process, the induced draft fan 8 is preferably always in an open state to form a negative pressure inside the system to promote the flue gas to flow towards the exhaust gas treatment device.

[0055] The solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be understood as limiting the protection scope of the present invention.

[0056] Example 1

[0057] Take the chemical wastewater of a chemical plant as an example. The chemical wastewater generated by the chemical plant is about 2m 3 / h, COD content of chemical wastewater is 44215mg / L, Cl - The content is 64281mg / L, SO4 2- The content is 37457mg / L, Na + The content is 85632mg / L, which is high-salt and high-COD wastewater. Figure 1 The system in the process treats the wastewater, and the specific operations are as follows:

[0058] After the combustion-supporting gas (natural gas) is introduced into the waste salt incinerator 2 and ignited, the temperature in the waste salt incinerator 2 is maintained at 800-1000° C., and then the blower 9 and the heat exchanger 5 are turned on to stabilize the hot air temperature of the heat exchanger 5 at 400-600° C., and then the above-mentioned chemical wastewater is introduced into the wastewater dryer 1, and the wastewater is atomized by the two-phase flow spray gun to form atomized wastewater and is sprayed out, and the atomized wastewater exchanges heat with the high-temperature air from the heat exchanger 5, and the atomized wastewater undergoes complete mass transfer and heat transfer, and the water in the atomized wastewater is converted into water vapor, and the salt, organic matter and other impurities in the atomized wastewater are solidified to obtain a waste salt mixture, the main components of which are sodium chloride, sodium sulfate and organic matter;

[0059] The waste salt mixture is carried by high-temperature air into the waste salt incinerator 2 and is incinerated together with the combustion-supporting gas. No additional air is needed to supplement oxygen. The organic matter in the waste salt mixture is completely incinerated and decomposed, and the salts are discharged into the molten salt collection tank 3 in a molten state. The wind curtain device 10 in the waste salt incinerator 2 extracts part of the hot air from the hot air outlet flue of the heat exchanger 5, forming a thin layer of wall-attached wind in the waste salt incinerator 2, isolating the wall surface of the waste salt incinerator 2 from the waste salt incineration area, and preventing the molten salt from adhering to the wall and causing wall scaling and corrosion; extracting part of the high-temperature flue gas from the outlet flue of the waste salt incinerator 2 into the gas insulation shell 4 to prevent the molten salt in the molten salt collection tank 3 from cooling and crystallizing. The molten salt in the molten salt collection tank 3 accumulates and fills the tank, and then is discharged for salt separation treatment to achieve resource utilization; the molten salt in the molten salt collection tank 3 is tested for composition, and the results show that there is no organic component, indicating that the organic matter in the waste salt mixture is completely incinerated and decomposed.

[0060] The high-temperature flue gas discharged from the waste salt incinerator 2 enters the heat exchanger 5, and exchanges heat with the cold air introduced by the blower 9, so that the high-temperature flue gas is suddenly cooled, and the high-temperature flue gas is cooled to 100-150°C, so as to prevent the flue gas from synthesizing organic matter again after slow cooling;

[0061] The cooled flue gas enters the cyclone dust collector 6 to remove the particulate matter carried in the flue gas, and then enters the exhaust gas processor 7 to remove NO x and SO x , and then obtain clean gas that meets emission standards.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-salt and high-COD wastewater treatment system, characterized in that: It comprises a wastewater dryer (1), wherein the wastewater dryer (1) is provided with a wastewater inlet, an air inlet and a waste salt outlet; A waste salt incinerator (2), wherein the waste salt incinerator (2) is provided with a waste salt inlet, a molten salt outlet, a combustion-supporting gas inlet and a flue gas outlet; the waste salt inlet is connected to the waste salt outlet of the wastewater dryer (1); A molten salt collecting tank (3), wherein the inlet of the molten salt collecting tank (3) is connected to the molten salt outlet of the waste salt incinerator (2), and the outer wall of the flue connecting the inlet of the molten salt collecting tank (3) and the molten salt outlet of the waste salt incinerator (2) and the outer wall of the molten salt collecting tank (3) are provided with a gas insulation shell (4); A heat exchanger (5), wherein the heat exchanger (5) is provided with a smoke inlet, a smoke outlet, an air inlet and an air outlet; the smoke inlet of the heat exchanger (5) is connected to the smoke outlet of the waste salt incinerator (2), the air inlet of the heat exchanger (5) is connected to the blower (9), and the air outlet of the heat exchanger (5) is connected to the air inlet of the wastewater dryer (1); A cyclone dust collector (6), the inlet of the cyclone dust collector (6) being in communication with the flue gas outlet of the heat exchanger; An exhaust gas processor (7), wherein the inlet of the exhaust gas processor (7) is connected to the outlet of the cyclone dust collector (6); The flue connecting the flue gas outlet of the waste salt incinerator (2) and the flue gas inlet of the heat exchanger (5) is provided with two branch flues, which are respectively referred to as a first branch flue and a second branch flue. The first branch flue is provided at the flue gas outlet side of the waste salt incinerator (2) and is connected to the inlet of the gas insulation shell (4). The second branch flue is provided at the flue gas inlet side of the heat exchanger (5) and is connected to the outlet of the gas insulation shell (4). The waste salt incinerator (2) comprises a straight section and a cone bucket arranged at the bottom of the straight section; an air curtain device (10) is arranged on the inner wall of the straight section; a branch flue is arranged on the flue connecting the air outlet of the heat exchanger (5) and the air inlet of the wastewater dryer (1), which is marked as a third branch flue, and the third branch flue is connected to the air curtain device (10).

2. The system according to claim 1, characterized in that The wastewater dryer (1) is provided with an atomizer, and the atomizer is a two-phase flow nozzle atomizer or a three-phase flow nozzle atomizer.

3. The system according to claim 1, characterized in that An electric scraper is arranged on the inner wall of the cone bucket, and an electric baffle door is arranged on the bottom of the cone bucket.

4. The system according to claim 1, characterized in that An induced draft fan (8) is provided on the outlet flue of the cyclone dust collector (6).

5. The system according to claim 1, characterized in that The tail gas processor (7) is an activated carbon adsorption tail gas processing device.

6. A method for treating high-salt and high-COD wastewater using the system according to any one of claims 1 to 5, characterized in that: The following steps are involved: Drying the high-salt and high-COD wastewater in a wastewater dryer (1) to obtain a waste salt mixture; The waste salt mixture enters a waste salt incinerator (2) and is incinerated together with a combustion-supporting gas to obtain molten salt and high-temperature flue gas, and the molten salt enters a molten salt collection tank (3); The high-temperature flue gas enters the heat exchanger (5) and exchanges heat with the cold air sent in by the blower (9) to obtain low-temperature flue gas and high-temperature air; the high-temperature air enters the wastewater dryer (1) to provide a heat source for drying the wastewater; The low-temperature flue gas enters the cyclone dust collector (6) for dust removal, and the obtained dust-removed flue gas enters the exhaust gas processor (7) for treatment, and is discharged after obtaining clean gas.

7. The method according to claim 6, characterized in that The incineration temperature is 800-1000°C.

8. The method according to claim 6, characterized in that The temperature of the high-temperature air is 400-600°C, and the temperature of the low-temperature flue gas is 100-150°C.

9. The method according to claim 6, characterized in that A portion of the high-temperature flue gas enters the gas insulation shell (4) from the first branch flue, and then returns from the second branch flue and enters the heat exchanger (5).

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