Freeze-evaporation combined with concentration sewage treatment system

Abstract

The present invention provides a sewage treatment system that combines freezing and evaporation with concentration. The sewage treatment system includes a sewage freezing treatment unit, a sewage evaporation treatment unit, and a refrigerant circuit unit. The sewage evaporation treatment unit includes an evaporation-condensation branch and an evaporative cooling circuit. Refrigerant is circulated within the refrigerant circuit unit, and the refrigerant circuit unit is used to recover and reuse the refrigerant's cold and heat sources. The present invention utilizes evaporation concentration technology that combines a sewage freezing treatment unit with a sewage evaporation treatment unit, significantly improving the concentration ratio and concentration efficiency. The plate ice concentration and evaporation concentration technology combine to share heat from the cold and heat sources of the concentrated sewage stock solution. This reduces the need for multiple heat pump configurations, reduces evaporation energy consumption, and significantly reduces sewage concentration energy consumption. This reduces the operational difficulty of setting up multiple heat sources, simplifies the equipment manufacturing process, and significantly saves operating and equipment costs.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment systems, and in particular to a sewage treatment system combining freezing, evaporation and concentration. Background Art

[0002] Currently, difficult-to-treat wastewater is commonly concentrated by evaporation. Electric, gas, and coal-fired boiler evaporation units are widely used both domestically and internationally. However, due to high operating temperatures and high steam pressures, the equipment and materials must meet high corrosion and pressure resistance requirements, requiring pressure-resistant operation and expensive pressure-bearing equipment. Coal-fired boiler evaporation and concentration units have been largely phased out or are in the process of being phased out due to severe environmental pollution. Gas-fired boiler evaporation and concentration units are currently less widely used due to safety and economic reasons. Electric-fired concentration units are increasingly used due to convenience and environmental considerations. However, single-stage electric boilers consume a significant amount of energy. Even with multi-stage evaporation, electric boiler evaporation and concentration units still consume approximately 200 to 300 kWh per ton of water, resulting in high equipment investment and energy consumption. Even with multi-stage evaporation and concentration, MVR steam compression evaporation and concentration systems still consume up to 200 kWh per ton of water. Furthermore, the process is complex, the equipment requirements are high, and the investment cost is high.

[0003] Heat pump low-temperature vacuum evaporation and concentration systems still consume a high energy consumption of 200 kWh per ton of water. Furthermore, the process requires vacuum pressure equipment, which is expensive and requires high investment. Using heat pump evaporation and dehumidification to concentrate wastewater allows for evaporation and concentration at low temperatures and atmospheric pressure, requiring less equipment and investment. Furthermore, because heat pumps improve energy efficiency by 3-4 times, energy consumption can be reduced to around 200 kWh per ton of water. However, energy consumption is still relatively high. Currently, there is considerable research on freeze concentration for difficult-to-treat wastewater. However, static freeze concentration suffers from the problem of carryover of raw liquid, resulting in poor purification efficiency, typically achieving only around 90% at most. Energy consumption is also high, typically around 100 kWh per ton of water. Therefore, most freeze concentration projects are focusing on dynamic freeze concentration technology. However, dynamic freeze concentration requires ice crystallization, separation, and washing, which presents technical drawbacks such as complex processes, high equipment requirements, high investment, and high energy consumption. Furthermore, energy consumption exceeds 100 kWh per ton of water, leading to significant wastewater treatment costs, making it difficult to widely apply in the wastewater treatment sector. Summary of the Invention

[0004] The purpose of the present invention is to provide a sewage treatment system with combined freezing and evaporation concentration, which adopts the sewage freezing treatment unit concentration technology of plate ice machine ice making superimposed on the sewage evaporation treatment unit concentration technology, has high concentration efficiency and high concentration ratio, and the sewage freezing treatment unit concentration technology shares the cold and heat sources of the evaporation treatment concentration, which not only reduces the heat pump configuration, but also reduces the evaporation energy consumption and significantly reduces the energy consumption of sewage concentration.

[0005] In order to achieve the above-mentioned purpose, the present invention provides the following technical solutions: a sewage treatment system for combined freezing, evaporation and concentration, the sewage treatment system includes a sewage freezing treatment unit, a sewage evaporation treatment unit and a refrigerant circuit unit, the refrigerant circuit unit includes a plate ice machine, a water-cooled condenser, an air-cooled condenser and a plate ice machine connected in sequence through pipelines; the refrigerant is circulated in the refrigerant circuit unit, and the refrigerant channel formed by the refrigerant passes through the components in the plate ice machine in sequence, including an expansion valve, the expansion valve converts the high-temperature and high-pressure liquid refrigerant of the air-cooled condenser into a refrigerant. The medium throttling is a low-temperature, low-pressure liquid refrigerant, an ice maker, and the internal refrigerant channel of the ice maker evaporates the low-temperature, low-pressure liquid refrigerant flowing out of the expansion valve into a low-temperature, low-pressure gaseous refrigerant; a compressor, the compressor compresses the low-temperature, low-pressure gaseous refrigerant flowing out of the ice maker into a high-temperature, high-pressure gaseous refrigerant; the high-temperature, high-pressure gaseous refrigerant then enters the water-cooled condenser and the air-cooled condenser in turn to be liquefied and converted into a low-temperature, low-pressure liquid refrigerant, and the low-temperature, low-pressure liquid refrigerant returns through the expansion valve to flow into the ice maker for recycling, and the refrigerant circuit unit is used to recover and reuse the cold and heat sources of the refrigerant.

[0006] Furthermore, the sewage freezing treatment unit includes a plate ice machine, an ice water tank, a high-pressure pump, a membrane filter and a purified water tank connected in sequence; the plate ice machine also includes a circulation tank inside, which is used to store ice-making circulating liquid; a circulation pump draws ice-making circulating liquid from the circulation tank and sprays it on the outer surface of the ice maker through a pipeline, and the circulation pump is used to circulate sewage when making ice; sewage is sprayed on the outer surface of the ice maker to make ice, and the sewage ice is purified; the sewage freezing treatment unit is used to circulate sewage in the ice maker to make ice, separate and decontaminate the unfrozen ice-making circulating liquid from the frozen ice cubes, melt the frozen ice cubes in the ice water tank, pressurize them through the high-pressure pump and enter the membrane filter to filter into purified water, and the purified water is discharged into the purified water tank.

[0007] Furthermore, the sewage evaporation treatment unit includes an evaporation heating circuit, which includes a water-cooled condenser, an evaporation kettle, an evaporation circulation pump and a water-cooled condenser connected in sequence; the evaporation heating circuit is used for evaporation, separation and purification of ice-making waste liquid that has not been made into ice after repeated circulation heating through the water-cooled condenser, evaporation kettle, evaporation circulation pump and water-cooled condenser.

[0008] Furthermore, the evaporation kettle of the sewage evaporation treatment unit is also connected to a concentrated liquid discharge branch, which includes an evaporation kettle, a drainage pump and a concentrated liquid pool; the concentrated liquid discharge branch is used to discharge the highly concentrated liquid that reaches a specified concentration after passing through the evaporation heating circuit into the concentrated liquid pool through the drainage pump.

[0009] Furthermore, the sewage evaporation treatment unit also includes an evaporation and condensation branch, which includes a cooler, a drainage pump, and a purified water tank connected in sequence; the evaporation and condensation branch unit is used to collect the steam in the evaporation kettle and enter the cooler to condense it into purified water, which is discharged into the purified water tank through the drainage pump.

[0010] Furthermore, the sewage evaporation treatment unit also includes an evaporative cooling circuit, which includes a cooler, an ice water tank, an ice water circulation pump, and a cooler connected in sequence; the evaporative cooling circuit is used for the circulating sewage to absorb the heat of the steam in the condensation branch in the cooler and release heat when the circulating sewage condenses into ice in the ice water tank.

[0011] Furthermore, the sewage treatment system also includes a liquid return circuit, which includes a plate ice machine, an ice water tank, a high-pressure pump, a membrane filter and a sewage main pipeline connected in sequence; after the circulating sewage or the sewage raw liquid is filtered through the membrane filter of the sewage freezing treatment unit, a small amount of relatively concentrated residual liquid remains, which is returned to the plate ice machine through the liquid return circuit, and circulates again from the plate ice machine into the sewage freezing treatment unit or the sewage evaporation treatment unit.

[0012] Furthermore, the sewage evaporation treatment unit further includes a vacuum pump, which is coupled to the evaporation kettle and is used to discharge gas from the evaporation system into the atmospheric environment to maintain the vacuum degree of the evaporation system.

[0013] Furthermore, the sewage evaporation treatment unit further includes a pressure gauge, which is fixedly connected to the evaporation kettle and is used to monitor the air pressure in the evaporation kettle.

[0014] Furthermore, the sewage evaporation treatment unit further includes a temperature meter, which is fixedly connected to the evaporation kettle and is used to monitor the temperature inside the evaporation kettle.

[0015] Analysis shows that the present invention discloses a sewage treatment system combining freezing, evaporation and concentration, which has the following technical effects:

[0016] 1. The sewage treatment system disclosed in the present invention adopts the evaporation concentration technology of a sewage freezing treatment unit superimposed on a sewage evaporation treatment unit, which significantly improves the concentration ratio and concentration efficiency.

[0017] 2. The sewage treatment system disclosed in the present invention adopts plate ice making and concentration superimposed on evaporation concentration technology. The heat of the cold and hot source refrigerant of the ice-making concentrated sewage raw liquid and the evaporated concentrated sewage raw liquid is shared, which not only reduces the multiple configurations of the heat pump, but also reduces the evaporation energy consumption, and significantly reduces the energy consumption of sewage concentration.

[0018] 3. Disclosure of the Invention The sewage treatment system disclosed in the present invention reduces the difficulty of setting up multiple heat sources, simplifies the equipment manufacturing process, and greatly saves the cost of operation and equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings and the accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. Among them:

[0020] Figure 1 A schematic flow diagram of an embodiment of a sewage treatment system using freeze-evaporation and concentration according to the present invention;

[0021] Explanation of the accompanying symbols: 1-plate ice machine; 2-ice water tank; 3-high-pressure pump; 4-membrane filter; 5-purified water tank; 6-drainage pump; 7-ice water circulation pump; 8-cooler; 9-sewage outlet pipe; 10-sewage inlet pipe; 11-air-cooled condenser; 12-water-cooled condenser; 13-evaporation kettle; 14-vacuum pump; 15-evaporation circulation pump; 16-liquid discharge pump; 17-concentrated liquid; 18-return liquid circuit; 19-condensation pipe. DETAILED DESCRIPTION

[0022] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. Each example is provided by way of explanation of the present invention and is not intended to limit the present invention. Indeed, it will be apparent to those skilled in the art that modifications and variations may be made in the present invention without departing from the scope or spirit of the present invention. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is intended that the present invention encompasses such modifications and variations as come within the scope of the appended claims and their equivalents.

[0023] In the description of the present invention, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and do not require that the present invention must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. The terms "connected", "connected", and "set" used in the present invention should be understood in a broad sense. For example, they can be fixed connections or detachable connections; they can be directly connected or indirectly connected through intermediate components; they can be wired electrical connections, radio connections, or wireless communication signal connections. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0024] An example of the present invention is shown in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and the description have been used to refer to like or similar parts of the present invention. As used herein, the terms "first," "second," and "third," etc. are used interchangeably to distinguish one component from another and are not intended to indicate the position or importance of an individual component.

[0025] like Figure 1 As shown, according to an embodiment of the present invention, a sewage treatment system for combined freezing, evaporation and concentration is provided, which includes a sewage freezing treatment unit and a sewage evaporation treatment unit. After the sewage from the sewage inlet pipe 10 enters the plate ice machine 1, the sewage freezing treatment unit includes a plate ice machine 1, an ice water tank 2, a high-pressure pump 3, a membrane filter 4 and a purified water tank 5 connected in sequence, wherein the plate ice machine 1 includes an expansion valve, an ice maker, a compressor, a circulation pump and a circulation tank; circulating liquid is extracted from the circulation tank and sprayed on the outer surface of the ice maker through a pipe for sewage circulation during ice making; the circulation tank is used to store excess ice-making circulating liquid that is not formed into ice by the ice maker; the circulating liquid is circulated in the circulation pump, the outer surface of the ice maker and the circulation tank in turn.

[0026] The wastewater freezing treatment unit circulates wastewater to form ice on the outer surface of the ice maker within the plate ice machine 1. After ice-making by the plate ice machine 1, the ice cubes undergo wastewater purification, separating the unfrozen circulating fluid from the frozen ice cubes. Specifically, the plate ice machine 1 within the wastewater freezing treatment unit uses an internal circulation pump to continuously pour circulating fluid over the surface of the ice maker, continuously forming and de-icing the ice. When the ice layer reaches 3-15 cm, it automatically breaks off. The de-iced ice breaks onto the mesh screen inside the ice maker, separating it from the wastewater and then dropping into the ice water tank 2. Crushed ice melts more easily in the ice water tank 2 than whole ice. Cold water flows through the ice water circulation pump 7 into the cooler 8, absorbing heat. The absorbed hot water returns to the ice water tank 2, causing the temperature of the ice water tank 2 to rise, melting the crushed ice. Once the crushed ice in the ice water tank 2 melts, it is forced through the high-pressure pump 3 into the membrane filter 4, where it undergoes further purification to produce high-quality purified water. The purified wastewater after the ice making process in the plate ice machine 1 is filtered by the membrane filter 4, which improves the applicability and efficiency of the membrane filter 4, and the wastewater purification efficiency is also improved accordingly. At the same time, the maintenance cycle and service life of the membrane filter 4 are greatly extended.

[0027] The wastewater treatment system also includes a return loop 18. The small amount of concentrated residual liquid remaining after filtration by the membrane filter 4 is returned through the return loop 18 to the sewage inlet pipe 10 and flows into the plate ice machine 1. The remaining concentrated residual liquid mixes with the original sewage in the sewage inlet pipe 10. The mixed sewage then passes from the ice machine to the sewage freezing unit for purification or to the sewage evaporation unit for purification through the ice-making waste liquid. From the sewage inlet pipe 10, the return loop includes connections to the plate ice machine 1, the ice water tank 2, the high-pressure pump 3, the membrane filter 4, the return loop 18, and the sewage inlet pipe 10. The small amount of concentrated residual liquid remaining after passing through the membrane filter 4 is returned through the return loop 18 to the plate ice machine 1 for further circulation in ice making or evaporation for purification. The frozen ice in the ice water tank 2 is melted, filtered through the membrane filter 4, and purified water is discharged into the purified water tank 5. The sewage purification rate through the sewage freezing unit can reach approximately 90%.

[0028] The remaining ice-making circulating liquid in the internal circulation tank of the plate ice machine 1 that has not been turned into ice enters the evaporation system after reaching a specified concentration. The evaporation system includes an evaporation heating circuit and an evaporation condensation branch unit; the evaporation heating circuit starts from the evaporation kettle 13, and the evaporation heating circuit includes the evaporation kettle 13, the evaporation circulation pump 15, the water-cooled condenser 12 and the evaporation kettle 13 connected in sequence; the circulating liquid comes from the evaporation kettle 13, and the replenishing liquid comes from the ice-making circulating liquid in the circulation tank inside the plate ice machine. The evaporation heating circuit is used to sequentially allow the ice-making circulating liquid that has not been turned into ice to enter the evaporation kettle 13, the evaporation circulation pump 15, and the water-cooled condenser 12, enter the water-cooled condenser 12 for heating and separation of water vapor, and finally return to the evaporation kettle 13. After repeated circulation and heating, the water in the circulating liquid is evaporated into water vapor for separation and purification; the heat released by the condensation and liquefaction of the refrigerant in the water-cooled condenser 12 is absorbed, and the temperature of the heated circulating liquid is about 35°C.

[0029] The waste liquid concentrated from the evaporator 13 is discharged into a concentrated liquid discharge branch, which includes the evaporator 13, a drainage pump 16, and a concentrated liquid tank 17 connected in sequence. The concentrated liquid in the lower layer of the evaporator 13 is discharged into the concentrated liquid tank 17 through the drainage branch. The concentrated liquid discharge branch is used to discharge the highly concentrated liquid that has reached a specified concentration through the evaporation heating circuit to the concentrated liquid tank 17 through the drainage pump 16. The highly concentrated liquid that has reached the specified concentration is then discharged from the evaporation system through the drainage pump 16. For example, a landfill leachate with a raw chloride ion concentration of 137 mg / L and a circulating liquid with a specified concentration of 650 mg / L after concentration is discharged into the concentrated liquid tank 17.

[0030] The evaporation kettle in the evaporation system is also connected to a vacuum pump 14, which is coupled to the evaporation kettle 13. The vacuum pump 14 is used to exhaust gas from the evaporation system to the atmosphere to maintain the vacuum level of the evaporation system. The evaporation system also includes a pressure gauge for monitoring the air pressure within the evaporation kettle 13 and a thermometer for monitoring the temperature within the evaporation kettle. The pressure gauge and thermometer are each fixedly connected to the evaporation kettle.

[0031] The water vapor discharged from the condensation pipe 19 of the evaporation kettle 13 is condensed into water through the evaporation condensation branch unit, and the evaporation condensation branch unit includes a cooler 8, a drain pump 6, and a purified water tank 5 connected in sequence; the evaporation condensation branch unit is used to collect the water vapor in the evaporation kettle 13 and flow into the cooler 8 to condense it into purified water, and then discharge it into the purified water tank 5 through the drain pump 6, thereby achieving the effect of evaporation purification. The water vapor in the evaporation kettle 13 in the condensation branch of the evaporation system flows into the cooler 8 to release heat to the ice water, and the condensation temperature is about 5°C. At the same time, the water vapor condenses into purified water, and then is discharged from the system by the drain pump 6.

[0032] The sewage treatment system also includes a refrigerant circuit unit, which includes a refrigerant connected to the plate ice machine 1, the water-cooled condenser 12, the air-cooled condenser 11 through pipes in sequence, and then returned to the plate ice machine 1, wherein the refrigerant passes through the expansion valve, the ice maker, and the compressor in sequence inside the plate ice machine 1; the expansion valve throttles the high-temperature and high-pressure liquid refrigerant in the air-cooled condenser 11 into a low-temperature and low-pressure liquid refrigerant, and the low-temperature and low-pressure liquid refrigerant enters the refrigerant channel inside the ice maker; the internal refrigerant channel of the ice maker evaporates the low-temperature and low-pressure liquid refrigerant flowing out of the expansion valve into a low-temperature and low-pressure gaseous refrigerant, and the compressor compresses the low-temperature and low-pressure gaseous refrigerant flowing out of the ice maker into a high-temperature and high-pressure gaseous refrigerant.

[0033] The expansion valve of the plate ice machine 1, the refrigerant channel inside the ice maker and the compressor are connected in sequence, and the refrigerant circulates in the refrigerant circuit unit. The refrigerant circuit unit is mainly used to recover and reuse the cold and heat sources of the refrigerant. The liquid refrigerant is converted into a low-temperature liquid refrigerant in the ice maker. After being pressurized by the compressor, the low-temperature liquid refrigerant is pressurized into a high-temperature gaseous refrigerant. A part of the high-temperature gaseous refrigerant is first converted into a liquid refrigerant in the water-cooled condenser 12, and the remaining part of the high-temperature gaseous refrigerant is then converted into a high-temperature and high-pressure liquid refrigerant in the air-cooled condenser 11. The high-temperature and high-pressure liquid refrigerant flows into the expansion valve of the plate ice machine 1 and is throttled into a low-pressure and low-temperature liquid, and then returns to the ice maker for further circulation. The refrigerant circulates in a loop connected to the compressor, water-cooled condenser 12, air-cooled condenser 11, expansion valve, ice maker, and compressor. The water-cooled condenser 12 transfers a portion of the heat condensed from the high-temperature gaseous refrigerant to the circulating sewage in the evaporative heating loop. The air-cooled condenser discharges excess heat from the water-cooled condenser 12 into the ambient air, discharging excess condensation heat from the ice maker to maintain the system's thermal balance. The water-cooled condenser 12 releases heat to the circulating sewage in the evaporative heating loop of the evaporative system. The sewage treatment system also includes an evaporative cooling loop, which includes a cooler 8, an ice water tank 2, an ice water circulation pump 7, and a cooler 8 connected in sequence. The evaporative cooling loop is used for the circulating sewage to absorb heat from the steam in the condensation branch in the cooler, and release heat when the circulating sewage melts ice in the ice water tank. The circulating sewage in the evaporative cooling loop pipeline circulates repeatedly in the ice water tank 2, the ice water circulation pump 7, the cooler 8, and the ice water tank 2 in turn. The circulating sewage absorbs the heat of the water vapor in the evaporative condensation branch unit in the cooler 8. After absorbing the heat, the circulating sewage enters the ice water tank 2 to melt the crushed ice in the ice water tank 2. The ice water circulation pump 7 is used to circulate the sewage in the evaporative cooling loop pipeline.

[0034] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0035] 1. Compared with electric boiler evaporation concentration, MVR steam compression evaporation concentration, or heat pump low-temperature vacuum evaporation concentration device, the total cost of the technical solution disclosed in the present invention can be significantly reduced by about 40% to 90%, and energy consumption can be reduced by up to about 60% to 95%.

[0036] 2. Compared with the conventional heat pump evaporation dehumidification and concentration device with an evaporation energy consumption of about 250kwh per ton of water, the high-efficiency and energy-saving sewage freezing and concentration technology disclosed in the present invention achieves an evaporation energy consumption of about 50kwh per ton of water, which can significantly reduce energy consumption by about 80%, saving more energy and cost.

[0037] 3. Compared with the static freezing concentration technology, which consumes about 100kwh of evaporation energy per ton of water, the high-efficiency and energy-saving sewage freezing concentration technology can achieve an evaporation energy consumption of about 50kwh per ton of water, which can significantly reduce energy consumption by about 50%, saving more energy and cost, and has a high purification rate.

[0038] 4. Compared with the dynamic freezing concentration technology, which consumes about 100kwh of evaporation energy per ton of water, the high-efficiency and energy-saving sewage freezing concentration technology can achieve an evaporation energy consumption of about 50kwh per ton of water, which can significantly reduce energy consumption by more than 50%, saving more energy and money, and has good purification effect, low energy consumption and low investment cost.

[0039] 5. Compared with the plate ice freezing and concentration technology, which consumes about 65kWh of evaporation energy per ton of water, the high-efficiency and energy-saving sewage freezing and concentration technology can achieve an evaporation energy consumption of about 50kWh per ton of water, which can significantly reduce energy consumption by more than 20%. The technical solution disclosed in the present invention increases the alternating recycling of the corresponding refrigerant cold and heat sources, which is more energy-saving and cost-effective.

[0040] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A sewage treatment system combining freezing, evaporation and concentration, characterized in that: The sewage treatment system includes a sewage freezing treatment unit, a sewage evaporation treatment unit and a refrigerant circuit unit. The sewage freezing treatment unit includes a plate ice machine, an ice water tank, a high-pressure pump, a membrane filter and a purified water tank connected in sequence; The sewage evaporation treatment unit includes: An evaporation heating circuit, comprising a water-cooled condenser, an evaporation kettle, an evaporation circulation pump, and a water-cooled condenser connected in sequence; the evaporation heating circuit is used for evaporation, separation, and purification of ice-making waste liquid that has not been made into ice after it enters the water-cooled condenser, the evaporation kettle, the evaporation circulation pump, and the water-cooled condenser and is repeatedly heated in a cycle; The evaporation and condensation branch includes a cooler, a drainage pump, and a purified water tank connected in sequence; the evaporation and condensation branch unit is used to collect the steam in the evaporation kettle and enter the cooler to condense it into purified water, which is then discharged into the purified water tank through the drainage pump; The evaporative cooling circuit includes a cooler, an ice water tank, an ice water circulation pump, and a cooler connected in sequence. The circulating sewage in the evaporative cooling circuit pipeline circulates repeatedly in the ice water tank, the ice water circulation pump, the cooler, and the ice water tank in sequence. The circulating sewage absorbs the heat of the water vapor in the evaporation and condensation branch unit in the cooler. After absorbing the heat, the circulating sewage enters the ice water tank to melt the crushed ice in the ice water tank. The refrigerant circuit unit includes a plate ice machine, a water-cooled condenser, an air-cooled condenser, and a plate ice machine connected in sequence through pipes; the refrigerant circulates inside the refrigerant circuit unit, and the refrigerant channel formed by the refrigerant passes through the following components in the plate ice machine in sequence: An expansion valve that throttles the high-temperature, high-pressure liquid refrigerant from the air-cooled condenser to a low-temperature, low-pressure liquid refrigerant; An ice maker, wherein an internal refrigerant channel of the ice maker evaporates the low-temperature and low-pressure liquid refrigerant flowing out of the expansion valve into a low-temperature and low-pressure gaseous refrigerant; A compressor compresses the low-temperature, low-pressure gaseous refrigerant flowing out of the ice maker into a high-temperature, high-pressure gaseous refrigerant; The high-temperature and high-pressure gaseous refrigerant then enters the water-cooled condenser and the air-cooled condenser in turn to be liquefied and converted into a low-temperature and low-pressure liquid refrigerant. The low-temperature and low-pressure liquid refrigerant returns to the ice maker through the expansion valve and circulates again. The refrigerant circuit unit is used to recover and reuse the cold and heat sources of the refrigerant.

2. The sewage treatment system of freeze-evaporation combined with concentration according to claim 1, characterized in that: The interior of the plate ice machine also includes: A circulation tank, the circulation tank being used to store ice-making circulating fluid; A circulation pump, which is used to extract ice-making circulating fluid from the circulation tank and spray the ice-making circulating fluid onto the outer surface of the ice maker through a pipeline. The circulation pump is used to circulate sewage during ice making; Sewage is sprayed on the outer surface of the ice maker to make ice, and the sewage ice making is purified; the sewage freezing treatment unit is used to circulate sewage in the ice maker to make ice, separate and remove contaminants from the ice-making circulating liquid that has not been made into ice and the ice cubes that have been frozen, melt the frozen ice cubes in the ice water tank, pressurize them through a high-pressure pump and enter the membrane filter to be filtered into purified water, and the purified water is discharged into the purification water tank.

3. The sewage treatment system of freeze-evaporation combined with concentration according to claim 1, characterized in that: The evaporation kettle of the sewage evaporation treatment unit is also connected to a concentrated liquid discharge branch, which includes an evaporation kettle, a drainage pump and a concentrated liquid pool; the concentrated liquid discharge branch is used to discharge the highly concentrated liquid that reaches a specified concentration after passing through the evaporation heating circuit into the concentrated liquid pool through the drainage pump.

4. The sewage treatment system of freeze-evaporation combined with concentration according to claim 2, characterized in that: The sewage treatment system also includes a liquid return circuit, which includes a plate ice machine, an ice water tank, a high-pressure pump, a membrane filter and a sewage main pipeline connected in sequence; after the circulating sewage or the sewage raw liquid is filtered through the membrane filter of the sewage freezing treatment unit, a small amount of relatively concentrated residual liquid remains, which is returned to the plate ice machine through the liquid return circuit, and circulates from the plate ice machine again into the sewage freezing treatment unit or the sewage evaporation treatment unit.

5. The sewage treatment system of freeze-evaporation combined with concentration according to claim 1, characterized in that: The sewage evaporation treatment unit further comprises a vacuum pump, which is coupled to the evaporation kettle and is used to discharge gas from the evaporation system to the atmosphere to maintain the vacuum degree of the evaporation system.

6. The sewage treatment system of freeze-evaporation combined with concentration according to claim 1, characterized in that: The sewage evaporation treatment unit further comprises a pressure gauge, which is fixedly connected to the evaporation kettle and is used to monitor the air pressure in the evaporation kettle.

7. The sewage treatment system of freeze-evaporation combined with concentration according to claim 1, characterized in that: The sewage evaporation treatment unit further comprises a temperature meter, which is fixedly connected to the evaporation kettle and is used to monitor the temperature inside the evaporation kettle.

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