Low-temperature heat pump evaporation equipment

Abstract

The invention discloses low-temperature heat pump evaporation equipment which comprises an evaporation system, a heat pump system, a vacuum system and a working condition adjusting system. Adjustable circulating water heat exchangers are arranged nearby an outlet of a condensation heat exchanger, an outlet of an evaporation heat exchanger and an outlet of a first compressor, a first adjusting valve, a second adjusting valve and a third adjusting valve are introduced to adjust the heat exchange amount of circulating water and a refrigerant, and the circulating water is allowed to absorb or release heat when flowing through different heat exchangers; therefore, the working condition fluctuation influence of the heat pump system can be solved at the first time, and the linkage influence caused by fluctuation is avoided. The working condition of the heat pump system is stabilized, and the working condition fluctuation of the evaporation system is effectively inhibited.

Description

Technical Field

[0001] This application relates to the field of low-temperature heat pump evaporation equipment and control technology, and in particular to a low-temperature heat pump evaporation system suitable for treating industrial wastewater. Background Technology

[0002] Low-temperature heat pump evaporators are an effective device for treating industrial wastewater. They combine low-temperature evaporation technology and heat pump technology. The heat pump system generates heat at its heating end to heat the wastewater, utilizing the characteristic that water boils at low temperatures under high negative pressure (vacuum) conditions, causing the wastewater to evaporate. At the cooling end of the heat pump system, the water vapor condenses upon contact with the cold air, thus separating the water from the wastewater and achieving highly efficient wastewater treatment.

[0003] The heat energy of the low-temperature heat pump evaporator is provided by the heat pump system. A heat pump system generally includes a compressor, which, along with an evaporator heat exchanger, expansion valve, and condenser heat exchanger, forms a heat pump circuit. The compressor draws in low-temperature refrigerant, compresses it, and discharges high-temperature, high-pressure gaseous refrigerant. This high-temperature, high-pressure gaseous refrigerant then enters the evaporator heat exchanger, where it exchanges heat and heats the wastewater inside the evaporator. After releasing heat, the refrigerant becomes liquid and leaves the evaporator heat exchanger, passing through the expansion valve into the condenser heat exchanger above the evaporator. The wastewater evaporates, and the water vapor in the evaporator rises to the area of ​​the condenser heat exchanger, where it exchanges heat with the refrigerant. The water vapor condenses into water and is discharged from the evaporator. The refrigerant, after absorbing heat and vaporizing, returns to the compressor inlet.

[0004] Under ideal design conditions, a heat pump system operates with ideal suction and discharge conditions and ideal refrigerant condensation and evaporation conditions, maintaining good heating efficiency. However, in practical applications, fluctuations in operating conditions make it difficult for the heat pump system to continuously operate under ideal conditions. Summary of the Invention

[0005] One of the purposes of this application is to provide a low-temperature heat pump evaporation device that introduces an operating condition regulation system. By controlling the circulating water in the operating condition regulation loop and the heat exchange of the refrigerant in the heat pump system, the state of the refrigerant can be adjusted, thereby regulating and stabilizing the operating condition of the heat pump system, effectively suppressing the operating condition fluctuations of the evaporation system, improving system stability, and reducing the overall operating energy consumption of the system.

[0006] In a first aspect, this application provides a low-temperature heat pump evaporation device, comprising an evaporation system, a heat pump system, a vacuum system, and a water temperature control system; wherein, The evaporation system includes an evaporator, an evaporation heat exchanger, and a condensation heat exchanger. The evaporation heat exchanger is used to provide the heat required for evaporation of the liquid in the evaporator, and the condensation heat exchanger is used to provide a condensation environment for the gas evaporated in the evaporator. The heat pump system includes a first compressor, a first heat exchanger, a second heat exchanger, a first expansion valve, and a refrigerant heat exchange device; the outlet of the first compressor is connected to the inlet of the first compressor in sequence through the first heat exchanger, the evaporator heat exchanger, the second heat exchanger, the first expansion valve, the condenser heat exchanger, and the refrigerant heat exchange device to form a heat pump circuit; The vacuum system is used to provide a vacuum environment for the evaporation system; The operating condition regulation system includes a circulating water tank, a first circulating water pump, a first regulating valve, a second regulating valve, and a third regulating valve. The lower part of the circulating water tank is connected to the inlet of the first circulating water pump, and the outlet of the first circulating water pump is connected to the inlet of the first regulating valve. The first outlet of the first regulating valve is connected to the inlet of the second regulating valve through the refrigerant heat exchanger, for heat exchange with the refrigerant flowing through the refrigerant heat exchanger. The second outlet of the first regulating valve is connected to the inlet of the second regulating valve, and the first outlet of the second regulating valve is connected to the inlet of the third regulating valve through the second heat exchanger. The first outlet of the third regulating valve is connected to the inlet of the circulating water tank through the first heat exchanger, and the second outlet of the third regulating valve is connected to the first inlet of the circulating water tank, forming an operating condition regulation loop.

[0007] In one possible implementation of the first aspect, the low-temperature heat pump evaporation device further includes a control module; a third temperature sensor and a third pressure sensor are provided at the refrigerant outlet of the refrigerant heat exchange device; the control module is used to: during the heating and / or evaporation stage, adjust the opening degree of the first outlet of the first regulating valve according to the third temperature value detected by the third temperature sensor and the third pressure value detected by the third pressure sensor.

[0008] In one possible implementation of the first aspect, the low-temperature heat pump evaporation device further includes a control module; a second temperature sensor and a second pressure sensor are provided at the refrigerant outlet of the second heat exchanger; the control module is used to: during the heating and / or evaporation stage, adjust the opening of the first outlet of the second regulating valve according to the second temperature value detected by the second temperature sensor and the second pressure value detected by the second pressure sensor.

[0009] In one possible implementation of the first aspect, the low-temperature heat pump evaporation device further includes a control module; a first temperature sensor and a first pressure sensor are provided at the refrigerant outlet of the first heat exchanger; the control module is used to: during the heating and / or evaporation stage, adjust the opening degree of the first outlet of the third regulating valve according to the first temperature value detected by the first temperature sensor and the first pressure value detected by the first pressure sensor.

[0010] In one possible implementation of the first aspect, the low-temperature heat pump evaporation equipment further includes a control module; the control module is also configured to: during the liquid inlet stage, control the first outlet of the first regulating valve, the first outlet of the second regulating valve, and the first outlet of the third regulating valve to be in a closed state.

[0011] In one possible implementation of the first aspect, the vacuum system includes an ejector, the first inlet of which is connected to the outlet of the first circulating water pump, the outlet of which is connected to the inlet of the first regulating valve, and the second inlet of which is connected to the evaporator.

[0012] In one possible implementation of the first aspect, the vacuum system includes an ejector and a second circulating water pump; the lower part of the circulating water tank is connected to the inlet of the second circulating water pump, the outlet of the second circulating water pump is connected to the first inlet of the ejector, the outlet of the ejector is connected to the second inlet of the circulating water tank, and the second inlet of the ejector is connected to the evaporator.

[0013] In one possible implementation of the first aspect, the low-temperature heat pump evaporation equipment further includes a water temperature regulation system, which is used to: cool the water in the circulating water tank during the liquid inlet stage and preheat the wastewater to be treated in the wastewater tank connected to the inlet of the evaporator; and / or heat the water in the circulating water tank during the heating stage; and / or cool or heat the water in the circulating water tank during the evaporation stage.

[0014] Secondly, this application provides a low-temperature heat pump evaporation device, including an evaporation system, a heat pump system, a vacuum system, an operating condition regulation system, and a water temperature regulation system; wherein, The evaporation system includes an evaporator, an evaporation heat exchanger, and a condensation heat exchanger. The evaporation heat exchanger is used to provide the heat required for evaporation of the liquid in the evaporator, and the condensation heat exchanger is used to provide a condensation environment for the gas evaporated in the evaporator. The heat pump system includes a first compressor, a first expansion valve, and a refrigerant heat exchanger; the outlet of the first compressor is connected to the inlet of the first compressor in sequence through the evaporator heat exchanger, the first expansion valve, the condenser heat exchanger, and the refrigerant heat exchanger to form a heat pump circuit. The vacuum system is used to provide a vacuum environment for the evaporation system; The operating condition adjustment system includes a circulating water tank, a first circulating water pump, and a first regulating valve; the lower part of the circulating water tank is connected to the inlet of the first circulating water pump, the outlet of the first circulating water pump is connected to the inlet of the first regulating valve, and the first outlet of the first regulating valve is connected to the inlet of the circulating water tank through the refrigerant heat exchange device. The inlet of the second regulating valve is connected to the refrigerant flowing through the refrigerant heat exchange device for heat exchange, and the second outlet of the first regulating valve is connected to the inlet of the circulating water tank to form an operating condition regulation loop. The water temperature regulation system is used to cool or heat the water in the circulating water tank.

[0015] In one possible implementation of the second aspect, the water temperature control system is used to cool the water in the circulating water tank during the liquid inlet phase and to preheat the wastewater to be treated in the wastewater tank connected to the inlet of the evaporator.

[0016] In one possible implementation of the second aspect, the water temperature regulation system is used to heat the water in the circulating water tank during the heating phase.

[0017] In one possible implementation of the second aspect, the water temperature regulation system is used to cool or heat the water in the circulating water tank during the evaporation phase.

[0018] In one possible implementation of the second aspect, the water temperature regulation system includes a main four-way valve, a second compressor, a circulating water heat exchanger, an air heat exchanger, a wastewater heat exchanger, a second expansion valve, and a secondary four-way valve. The first port of the main four-way valve is connected to the outlet of the second compressor; the second port of the main four-way valve is connected to the first interface of the circulating water heat exchanger; the third port of the main four-way valve is connected to the inlet of the second compressor; the fourth port of the main four-way valve is connected to the first interface of the wastewater heat exchanger; the second interface of the circulating water heat exchanger is connected to the first port of the secondary four-way valve via the second expansion valve; the second port of the secondary four-way valve is connected to the fourth port of the secondary four-way valve via the air heat exchanger; and the third port of the secondary four-way valve is connected to the second interface of the wastewater heat exchanger. Its control method can be similar to that of the first aspect.

[0019] In one possible implementation of the second aspect, the water temperature regulation system includes a main four-way valve, a second compressor, a circulating water heat exchanger, an air heat exchanger, a wastewater heat exchanger, and a second expansion valve. The first port of the main four-way valve is connected to the outlet of the second compressor, the second port of the main four-way valve is connected to the first interface of the circulating water heat exchanger, the third port of the main four-way valve is connected to the inlet of the second compressor, and the fourth port of the main four-way valve is connected to the first interface of the wastewater heat exchanger. The second interface of the circulating water heat exchanger is connected sequentially through the second expansion valve, the air heat exchanger, and the second interface of the wastewater heat exchanger. Its control method can be similar to that of the first aspect.

[0020] In one possible implementation of the second aspect, the vacuum system includes an ejector, the first inlet of which is connected to the outlet of the first circulating water pump, the outlet of which is connected to the inlet of the first regulating valve, and the second inlet of which is connected to the evaporator.

[0021] In one possible implementation of the second aspect, the vacuum system includes an ejector and a second circulating water pump; the lower part of the circulating water tank is connected to the inlet of the second circulating water pump, the outlet of the second circulating water pump is connected to the first inlet of the ejector, the outlet of the ejector is connected to the second inlet of the circulating water tank, and the second inlet of the ejector is connected to the evaporator. Attached Figure Description

[0022] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the structure of the first embodiment of the low-temperature heat pump evaporation equipment of this application.

[0024] Figure 2 A schematic diagram of the structure of the vacuum system and the operating condition regulation system using a circulating water pump in the second embodiment of the low-temperature heat pump evaporation equipment of this application.

[0025] Figure 3 A schematic diagram of the structure of the vacuum system and the operating condition regulation system using independent circulating water pumps in the third embodiment of the low-temperature heat pump evaporation equipment of this application.

[0026] Figure 4 A schematic diagram of a water temperature regulation system is introduced in the fourth embodiment of the low-temperature heat pump evaporation equipment of this application.

[0027] Figure 5-1A schematic diagram of the cooling mode of the first implementation of the water temperature regulation system in this application.

[0028] Figure 5-2 A schematic diagram of the heating mode of the first implementation of the water temperature regulation system in this application.

[0029] Figure 6-1 A schematic diagram of the cooling mode of the second implementation of the water temperature regulation system in this application.

[0030] Figure 6-2 A schematic diagram of the heating mode of the second implementation of the water temperature regulation system in this application.

[0031] Figure 7 A schematic diagram of the structure of a water temperature regulation system is included in the fifth embodiment of the low-temperature heat pump evaporation equipment of this application.

[0032] Figure 8 A schematic diagram of the structure of a water temperature regulation system is included in the sixth embodiment of the low-temperature heat pump evaporation equipment of this application.

[0033] Figure 9 A schematic diagram of the structure in the seventh embodiment of the low-temperature heat pump evaporation equipment of this application, in which the refrigerant heat exchange device is replaced with a ring-type heat exchanger.

[0034] Figure 10 A schematic diagram of the structure in the eighth embodiment of the low-temperature heat pump evaporation equipment of this application, in which the refrigerant heat exchange device is replaced with a ring-type heat exchanger.

[0035] Figure 11 A schematic diagram of the structure in the ninth embodiment of the low-temperature heat pump evaporation equipment of this application, in which the refrigerant heat exchange device is replaced with a ring-type heat exchanger.

[0036] Explanation of reference numerals in the attached figures: Evaporator 100; Condensation tank 1001; Evaporative heat exchanger 101; Condensation heat exchanger 102; Inner tube 1021; Outer tube 1022; Wastewater tank 103; Inlet valve 121; First compressor 201; first heat exchanger 202; second heat exchanger 203; first expansion valve 221; first temperature sensor 231; first pressure sensor 232; second temperature sensor 233; second pressure sensor 234; third temperature sensor 235; third pressure sensor 236; First circulating water pump 301; circulating water tank 302; refrigerant heat exchanger 303; first regulating valve 321; inlet 3213 of the first regulating valve; first outlet 3211 of the first regulating valve; second outlet 3212 of the first regulating valve; second regulating valve 322; inlet 3223 of the second regulating valve; first outlet 3221 of the second regulating valve; second outlet 3222 of the second regulating valve; third regulating valve 323; inlet 3233 of the second regulating valve; first outlet 3231 of the second regulating valve; second outlet 3232 of the second regulating valve; flow sensor 331; fifth temperature sensor 332; Second compressor 401; circulating water heat exchanger 402; air heat exchanger 403; sewage heat exchanger 404; main four-way valve 421; first port 4211 of the main four-way valve; second port 4212 of the main four-way valve; third port 4213 of the main four-way valve; fourth port 4214 of the main four-way valve; second expansion valve 422; auxiliary four-way valve 423; first port 4231 of the auxiliary four-way valve; second port 4232 of the auxiliary four-way valve; third port 4233 of the auxiliary four-way valve; fourth port 4234 of the auxiliary four-way valve; fourth temperature sensor 431; fourth pressure sensor 432; sixth temperature sensor 433; sixth pressure sensor 434; Ejector 501; First inlet of ejector 5011; Second inlet of ejector 5012; Outlet of ejector 5013; Second circulating water pump 502; Vacuum pipeline 511. Detailed Implementation

[0037] To enable those skilled in the art to better understand the technical solutions of the embodiments of this application, the application will be described below in conjunction with the accompanying drawings and specific implementation methods.

[0038] Common low-temperature heat pump evaporators face challenges such as variable operating conditions and high energy consumption in practical applications.

[0039] On the one hand, unlike ordinary air-source or water-source heat pump systems, low-temperature heat pump evaporators used for wastewater treatment face more complex and variable operating conditions. For example, the heat exchange efficiency and required heat vary at different stages of wastewater inflow, heating, and evaporation. Furthermore, different types of wastewater have complex compositions, and even the concentration of the same type of wastewater changes continuously at different evaporation times. This leads to continuous changes in the physical properties and heat exchange characteristics of the wastewater, resulting in different heat exchange efficiencies and required heat during treatment. Additionally, scaling and salt precipitation, which commonly occur in wastewater treatment heat exchangers, also affect heat exchange efficiency.

[0040] On the other hand, ordinary air-source or water-source heat pumps typically only focus on the heating end, while the heat absorption (cooling) end relies on a relatively stable and independent air or water heat source. In other words, the heating and cooling ends are relatively decoupled or weakly correlated. However, heat pump systems using low-temperature heat pump evaporators for wastewater treatment are different. Their heating and cooling ends influence each other, and the heat pump system also interacts with the evaporation system. This can sometimes lead to chain reactions, causing drastic fluctuations in operating conditions, or even malfunctioning.

[0041] For example, when the system is in the heating phase (before steam is generated) or the concentration of wastewater inlet increases (boiling point rises, making evaporation more difficult), the absence or reduction of steam in the evaporator will decrease the heat exchange of refrigerant in the condenser heat exchanger. This results in insufficient heat absorption by the refrigerant in the condenser heat exchanger, preventing complete vaporization. This leads to lower pressure and temperature of the refrigerant returning to the compressor, lower compressor inlet pressure, and further increased superheat of the refrigerant at the compressor outlet. In other words, the compressor operates less efficiently at low suction pressure, but to maintain capacity, its discharge superheat increases. This means the refrigerant delivered to the evaporator heat exchanger is at a higher temperature but lower quality (heat exchange efficiency), reducing the heat exchange capacity and efficiency of the evaporator heat exchanger. Consequently, the evaporator heats the wastewater less effectively, reducing the amount of steam generated by the boiling wastewater in the evaporator, further worsening the heat exchange of the condenser heat exchanger.

[0042] For example, as evaporation proceeds, the concentration of wastewater inside the evaporator gradually increases, or scale forms on the surface of the evaporative heat exchanger, leading to a decrease in evaporative heat exchange efficiency. This reduces water vapor production, resulting in insufficient heat exchange in the condenser heat exchanger; furthermore, the high-temperature refrigerant cannot completely release heat and liquefy in the evaporative heat exchanger, affecting the vaporization effect of the refrigerant after passing through the expansion valve, further impacting the compressor's operating efficiency.

[0043] This application embodiment introduces an operating condition regulation system into a low-temperature heat pump evaporation system. By controlling the circulating water in the operating condition regulation loop and the heat exchange of the refrigerant in the heat pump system, the state of the refrigerant can be adjusted, including rapid adjustment of the exhaust superheat, the subcooling before expansion, and the suction superheat, thereby regulating and stabilizing the operating condition of the heat pump system, reducing the coupling effect between the heating and cooling ends of the heat pump system, effectively suppressing the operating condition fluctuations of the evaporation system, improving system stability, and thus reducing the overall operating energy consumption of the system.

[0044] See Figure 1 This application provides a low-temperature heat pump evaporation device, including an evaporation system, a heat pump system, a vacuum system, and an operating condition regulation system.

[0045] The evaporation system includes an evaporator 100, an evaporative heat exchanger 101, and a condensing heat exchanger 102.

[0046] Evaporator 100 is used to contain wastewater. Evaporative heat exchanger 101 is mainly used to provide the heat required for evaporation of the liquid (e.g., industrial wastewater) within the evaporator. In some possible implementations, the evaporative heat exchanger can be a tubular heat exchanger disposed within the evaporator; it can also be a plate heat exchanger disposed at the bottom of the evaporator; or it can be other possible heat exchanger forms, which are not limited in this application.

[0047] The condensing heat exchanger 102 can be used to absorb the heat of the gas evaporated in the evaporator, thereby providing a condensing environment for the gas evaporated in the evaporator 100. In some possible implementations, the condensing heat exchanger 102 can be located on the upper part of the evaporator 100. For example, a condensation tank 1001 can be provided on the upper tank wall of the evaporator 100, and the condensing heat exchanger 102 can be located in the condensation tank 1001. In other possible implementations, the condensing heat exchanger 102 can be located outside the evaporator 100, and its height can be higher, lower, or flush with the evaporator 100; this application does not limit this. The condensing heat exchanger can be a common tubular heat exchanger, or a co-tube type or other possible forms of heat exchanger. When a co-tube heat exchanger is used, it can replace the function of the refrigerant heat exchange device in the operating condition regulation system, which will be further explained in a separate paragraph later.

[0048] Vacuum systems are used to provide a vacuum environment for evaporation systems.

[0049] In some possible implementations of the vacuum system, the system includes an ejector, a vacuum pump, and a water tank. The first inlet of the ejector can be connected to the outlet of the water tank via the vacuum pump, the second inlet of the ejector is connected to the evaporator via a vacuum line, and the outlet of the ejector can be connected to the inlet of the water tank. In some possible implementations, the vacuum line can be connected to the condenser tank of the evaporator. Water flowing from the water tank is accelerated by the vacuum pump and flows at high speed through the ejector, generating a Venturi effect. This draws non-condensable gases, incompletely condensed vapor, and condensate from the evaporator into the ejector through the vacuum line, and then into the water tank. This creates a certain degree of vacuum in the evaporator and, in evaporation mode, effectively draws condensate into the water tank, preventing condensate from accumulating in the condenser tank.

[0050] In some other possible implementations of the vacuum system, the circulating water tank and the first circulating water pump in the operating condition control system can be reused to form components of the vacuum system. In still other possible implementations of the vacuum system, the vacuum system has a separate second circulating water pump, and only the circulating water tank in the operating condition control system can be reused to form components of the vacuum system. These implementations will be further elaborated in a separate paragraph later.

[0051] Depending on the operating status of the evaporator, the entire evaporation system can be divided into stages such as liquid feeding, heating, and evaporation.

[0052] During the liquid inlet stage, a vacuum (e.g., a negative pressure of 50-100 mbar) is first generated in the evaporator 100 through a vacuum system. After the set vacuum is reached, the liquid inlet valve 121 is opened to draw the wastewater to be treated into the evaporator 100.

[0053] Once the wastewater reaches a certain level, it enters the heating stage, and the heat pump system starts. The wastewater is located at the bottom of the evaporator 100 and is heated by the high-temperature, high-pressure refrigerant on the other side of the evaporative heat exchanger 101.

[0054] Once the wastewater reaches its boiling point, the evaporation system enters the evaporation stage. During this stage, the heat pump system continues to operate, and the wastewater in the evaporator heat exchanger 101 is heated and boils, producing water vapor. The water vapor rises to the area where the condenser heat exchanger 102 is located at the top of the evaporator 100. Due to the low-temperature environment generated by the refrigerant vaporization in the condenser heat exchanger 102, the steam condenses into distilled water upon encountering the cold environment.

[0055] The heat energy of the low-temperature heat pump evaporation equipment is provided by a heat pump system. The heat pump system may include a first compressor 201, a first heat exchanger 202, a second heat exchanger 203, a first expansion valve 221, and a refrigerant heat exchange device 303; the outlet of the first compressor 201 is connected to the inlet of the first compressor 201 in sequence through the first heat exchanger 202, the evaporation heat exchanger 101, the second heat exchanger 203, the first expansion valve 221, the condensation heat exchanger 102, and the refrigerant heat exchange device 303, forming a heat pump circuit.

[0056] The refrigerant circulating in the heat pump circuit can be summarized as follows: The first compressor 201 draws in low-temperature, low-pressure refrigerant and, after compression, discharges high-temperature, high-pressure gaseous refrigerant. The gaseous refrigerant first flows through the first heat exchanger 202, where some superheat is removed. It then enters the evaporator heat exchanger 101, where it condenses and releases heat, heating the wastewater on the other side of the evaporator 101. After heat exchange, it becomes liquid refrigerant. The liquid refrigerant then enters the second heat exchanger 203, where it is further cooled and subcooled. Next, the liquid refrigerant passes through the first expansion valve 221 and becomes a low-temperature, low-pressure gas-liquid mixture. This mixture enters the condenser heat exchanger 102, where it absorbs heat from the water vapor in the evaporator 100 and completely vaporizes, providing the necessary condensation environment for the evaporation system and condensing the water vapor. Finally, the low-temperature, low-pressure gaseous refrigerant returns to the inlet of the first compressor 201 via the refrigerant heat exchanger 303, completing the working cycle.

[0057] The operating condition regulation system mainly regulates the state of the refrigerant by controlling the heat exchange between the circulating water in the operating condition regulation loop and the refrigerant in the heat pump system. It may include a circulating water tank 302, a first circulating water pump 301, a first regulating valve 321, a second regulating valve 322 and a third regulating valve 323.

[0058] The first regulating valve 321, the second regulating valve 322, and the third regulating valve 323 can, exemplarily, be three-way valves. Each valve has one inlet and two outlets, and the flow distribution can be adjusted by controlling the opening degree. That is, by adjusting the valve opening degree, the liquid flowing in from the inlet is distributed to the two outlets in different proportions. When the opening degree of the three-way regulating valve is x%, the flow rate at the first outlet is x% of the inlet flow rate, and the flow rate at the second outlet is (100-x)% of the inlet flow rate.

[0059] The lower part of the circulating water tank 302 is connected to the inlet of the first circulating water pump 301. The outlet of the first circulating water pump 301 is connected to the inlet 3213 of the first regulating valve. The first outlet 3211 of the first regulating valve is connected to the inlet 3223 of the second regulating valve through a refrigerant heat exchanger, for heat exchange with the refrigerant flowing through the refrigerant heat exchanger. The second outlet 3212 of the first regulating valve is connected to the inlet 3223 of the second regulating valve. The first outlet 3221 of the second regulating valve is connected to the inlet 3233 of the third regulating valve through the second heat exchanger 203. The second outlet 3222 of the second regulating valve is connected to the inlet 3233 of the third regulating valve. The first outlet 3231 of the third regulating valve is connected to the inlet of the circulating water tank 302 through the first heat exchanger 202. The second outlet 3232 of the third regulating valve is connected to the first inlet of the circulating water tank 302. This forms the operating condition regulation loop.

[0060] In the operating condition regulation loop, circulating water flows out from the circulating water tank 302, is pressurized by the first circulating water pump 301, and then enters the first regulating valve 321. According to system requirements, part of the circulating water flows through the refrigerant heat exchange device 303, and part flows directly to the second regulating valve 322. Similarly, the second regulating valve 322 distributes the circulating water to the second heat exchanger 203 or directly to the third regulating valve 323. The third regulating valve 323 distributes the circulating water to the first heat exchanger 202 or directly back to the circulating water tank 302.

[0061] This design places adjustable circulating water heat exchangers near the outlets of the condenser, evaporator, and first compressor, allowing the circulating water to absorb or release heat as it flows through different heat exchangers. This regulates the refrigerant state and allows fluctuations in the heat pump system's operating conditions to be addressed immediately, preventing cascading effects. This helps stabilize the heat pump system's operating conditions and effectively suppresses fluctuations in the evaporator system's operating conditions.

[0062] Among some possible implementations of refrigerant heat exchangers, see [link to relevant documentation]. Figure 1 The refrigerant heat exchanger 303 can be an independent heat exchanger, such as a plate or shell-and-tube heat exchanger, and has a water passage and a refrigerant passage. The first outlet 3211 of the first regulating valve is connected to the inlet 3223 of the second regulating valve through the water passage; the refrigerant outlet of the condenser heat exchanger 102 is connected to the inlet of the first compressor 201 through the refrigerant passage. With this design, when no steam is generated, the refrigerant heat exchanger 303 can provide the heat required for refrigerant vaporization through circulating water, and has good adjustment freedom, allowing the refrigerant to achieve complete vaporization before returning to the compressor, thus effectively controlling fluctuations in operating conditions.

[0063] The low-temperature heat pump evaporation equipment also includes a control module. The control module can be implemented, for example, by a PLC or microprocessor, which connects to various sensors and actuators (such as various regulating valves).

[0064] During the liquid inlet phase, the heat pump system has not yet started, and there is no need for refrigerant heat exchange. At this time, all three regulating valves can be completely closed. In some implementations, the control module is also used to: during the liquid inlet phase, control the first outlet 3211 of the first regulating valve, the first outlet 3221 of the second regulating valve, and the first outlet 3231 of the third regulating valve to be closed, i.e., the opening degree is 0%. At this time, all circulating water from the first circulating water pump 301 flows out from the second outlet 3212 of the first regulating valve and does not enter the refrigerant heat exchanger 303. Then, after passing through the inlet 3223 of the second regulating valve, all the circulating water flows out from the second outlet 3222 of the second regulating valve and does not flow into the second heat exchanger 203. Next, after passing through the inlet 3233 of the third regulating valve, all the circulating water flows out from the second outlet 3232 of the third regulating valve and flows back into the circulating water tank 302.

[0065] The heat pump system operates while the evaporation system is in the heating or evaporation phase. The control module can quickly respond to changes in system operating conditions, enabling automated adjustments and thus rapidly mitigating the impact of system fluctuations, preventing cascading effects.

[0066] In some implementations, a third temperature sensor 235 and a third pressure sensor 236 are provided at the refrigerant outlet of the refrigerant heat exchanger 303 to detect the temperature and pressure data at this location (hereinafter referred to as the third temperature value and the third pressure value for easy distinction), thereby enabling the determination of the refrigerant's state at this location.

[0067] The control module is used to: during the heating and / or evaporation stages, adjust the opening of the first outlet 3211 of the first regulating valve according to a third temperature value and a third pressure value. Optionally, when the refrigerant has not fully absorbed heat and vaporized in the condenser heat exchanger 102 and has a certain degree of thermal superheat, the control module can control to increase the opening of the first outlet 3211 of the first regulating valve, thereby increasing the amount of circulating water flowing into the refrigerant heat exchange device 303 to supplement the heat that the refrigerant can absorb. Optionally, when the superheat of the refrigerant reaches or exceeds the ideal value, the control module can control to decrease the opening of the first outlet 3211 of the first regulating valve, thereby reducing the amount of circulating water flowing into the refrigerant heat exchange device 303 and decreasing the amount of heat that the refrigerant can absorb.

[0068] In this way, the control module adjusts the amount of circulating water flowing into the refrigerant heat exchanger to quickly regulate the heat absorption of the refrigerant in the refrigerant heat exchanger, thereby regulating and stabilizing the temperature and pressure of the refrigerant entering the first compressor inlet, alleviating the problem caused by insufficient heat absorption of the refrigerant in the condenser heat exchanger, and thus stabilizing the operating conditions of the heat pump system.

[0069] After the circulating water flows through the refrigerant heat exchanger 303, its temperature decreases. After passing through the second regulating valve 322, a portion of the circulating water enters the second heat exchanger 203. One side of the second heat exchanger 203 contains the circulating water, while the other side contains refrigerant that has already exchanged heat with the wastewater and is flowing out of the evaporator heat exchanger 101. Due to variations in the heat exchange efficiency of the evaporator heat exchanger 101, the refrigerant may be in a state of insufficient superheat or incomplete liquefaction after exiting the evaporator heat exchanger 101.

[0070] In some implementations, a second temperature sensor 233 and a second pressure sensor 234 are provided at the refrigerant outlet of the second heat exchanger 203 to detect the temperature and pressure data at this location (hereinafter referred to as the second temperature value and the second pressure value for easy distinction), thereby enabling the determination of the refrigerant's state at this location.

[0071] The control module is used to: adjust the opening degree of the first outlet 3221 of the second regulating valve according to the second temperature value and the second pressure value during the heating and / or evaporation stage.

[0072] Optionally, when it is determined that the refrigerant at the refrigerant outlet of the second heat exchanger 203 has not reached complete liquefaction and has an ideal subcooling, the control module can control to increase the opening of the first outlet 3221 of the second regulating valve, thereby increasing the amount of circulating water flowing into the second heat exchanger 203 and allowing the circulating water to carry away more heat from the refrigerant. Optionally, when the subcooling of the refrigerant at this point reaches or exceeds the ideal subcooling, the control module can control to decrease the opening of the first outlet 3221 of the second regulating valve, thereby reducing the amount of circulating water flowing into the second heat exchanger 203 and thus reducing the heat exchange between the circulating water and the refrigerant in the second heat exchanger 203.

[0073] In this way, the heat exchange capacity of the refrigerant in the circulating water and the second heat exchanger can be quickly adjusted, thereby alleviating the problems caused by changes in the heat exchange efficiency of the evaporator heat exchanger, namely, the problem of insufficient superheat or incomplete liquefaction of the refrigerant leaving the evaporator heat exchanger, and thus stabilizing the operating conditions of the heat pump system.

[0074] After the circulating water flows through the second heat exchanger 203, its temperature rises. After passing through the third regulating valve 323, a portion of the circulating water enters the first heat exchanger 202. One side of the first heat exchanger 202 contains the circulating water, and the other side contains high-temperature, high-pressure gaseous refrigerant from the outlet of the first compressor 201. The refrigerant at the outlet of the first compressor 201 has a certain degree of superheat, which reduces the condensation heat release efficiency of the refrigerant in the evaporator heat exchanger 101. By exchanging heat with the circulating water in the first heat exchanger 202, the superheat of the refrigerant at this location can be removed.

[0075] In some implementations, a first temperature sensor 231 and a first pressure sensor 232 are provided at the refrigerant outlet of the first heat exchanger 202 to detect the temperature and pressure data at this location (hereinafter referred to as the first temperature value and the first pressure value for easy distinction), thereby enabling the determination of the refrigerant's state at this location.

[0076] The control module is used to: adjust the opening degree of the first outlet 3231 of the third regulating valve according to the first temperature value and the first pressure value during the heating and / or evaporation stage.

[0077] Optionally, when a high superheat of the refrigerant at the refrigerant outlet of the first heat exchanger 202 is detected, the control module can control to increase the opening of the first outlet 3231 of the third regulating valve, thereby increasing the amount of circulating water flowing into the first heat exchanger 202 and reducing the superheat of the refrigerant. Optionally, when the superheat of the refrigerant at the refrigerant outlet of the first heat exchanger 202 is detected to be at or below the ideal superheat, the control module can control to decrease the opening of the first outlet 3231 of the third regulating valve, thereby reducing the amount of circulating water flowing into the first heat exchanger 202 and thus reducing the heat exchange between the refrigerant and the circulating water in the first heat exchanger 202.

[0078] In this way, the heat exchange capacity of the circulating water and the refrigerant in the first heat exchanger can be quickly adjusted, thereby alleviating the problem of reduced heat exchange efficiency in the evaporator heat exchanger due to the superheat of the refrigerant leaving the outlet of the first compressor, and thus stabilizing the operating conditions of the heat pump system.

[0079] The implementation method of this application embodiment enables the operating condition regulation system to quickly adjust to changes in wastewater type and concentration, as well as different operating stages of the evaporator, suppressing fluctuations and chain reactions, stabilizing the operating condition of the heat pump system, and reducing the overall operating energy consumption of the system. Furthermore, the circulating water absorbs heat from the refrigerant in the heat pump circuit in the first and / or second heat exchangers, and releases this heat to the refrigerant in the heat pump circuit in the refrigerant heat exchange device, thus reusing the energy that would otherwise be dissipated in heat absorption, achieving energy recycling and further reducing energy consumption. Moreover, the circulating water first flows through the low-temperature refrigerant heat exchange device, then through the high-temperature second heat exchanger, and then through the even higher-temperature first heat exchanger; this flow from low to high temperature ensures high heat exchange efficiency.

[0080] The operating condition control system uses three regulating valves to distribute the circulating water flow to different heat exchangers (refrigerant heat exchanger, second heat exchanger, and first heat exchanger). When the opening of any regulating valve changes, it effectively alters the resistance characteristics of the entire circulating water loop. This can lead to inaccurate flow control of the circulating water, affecting the heat exchange between the circulating water and the refrigerant. Therefore, in some implementations, a flow sensor 331 can be installed at the outlet of the first circulating water pump 301. The control module can be used to: perform frequency conversion control on the first circulating water pump 301 based on the flow value fed back by the flow sensor 331. Optionally, if the detected flow value is lower than a preset target area, the control module can increase the speed of the first circulating water pump 301, increasing the pump output and raising the flow back to the preset target area. Optionally, if the detected flow value is higher than the preset target area, the control module can decrease the speed of the first circulating water pump 301, decreasing the pump output and reducing the flow back to the preset target area. In this way, a stable circulating water flow can be obtained when adjusting the circulating water flow distribution through the regulating valve, which helps to achieve a more precise heat exchange control effect.

[0081] As mentioned above, in some other possible implementations of the vacuum system, the circulating water tank 302 and the first circulating water pump 301 in the operating condition regulation system can be reused to form components of the vacuum system.

[0082] Optionally, see Figure 2 The vacuum system includes an ejector 501, the first inlet 5011 of which is connected to the outlet of the first circulating water pump 301, the outlet 5013 of which is connected to the inlet 3213 of the first regulating valve, and the second inlet 5012 of which is connected to the upper part of the evaporator 100.

[0083] In this implementation, the ejector 501 directly shares the circulating water with the operating condition regulation loop. Based on the Venturi effect, circulating water flows out from the first circulating water pump 301 and is ejected at high speed through the first inlet 5011 of the ejector, creating negative pressure at the second inlet 5012, drawing air from the evaporator 100 to form a vacuum. The ejector outlet 5013 is connected to the inlet 3213 of the first regulating valve, allowing the circulating water to continue participating in the operating condition regulation. This design simplifies the system but may be affected by the operation of the regulating valve, causing fluctuations in the flow rate of the ejector 501.

[0084] Optionally, see Figure 3 The vacuum system includes an ejector 501 and a second circulating water pump 502; the lower part of the circulating water tank 302 is connected to the inlet of the second circulating water pump 502, the outlet of the second circulating water pump 502 is connected to the first inlet 5011 of the ejector, the outlet 5013 of the ejector is connected to the second inlet of the circulating water tank 302, and the second inlet 5012 of the ejector is connected to the upper part of the evaporator 100.

[0085] In this implementation, the first circulating water pump is no longer used to supply water to the ejector; instead, a second circulating water pump is added specifically for the ejector. This makes the ejector's water supply independent of the operating condition control loop, resulting in more stable ejector operation. The flow rate and pressure are not affected by the adjustment of the regulating valve opening, avoiding flow interference and ensuring higher stability in vacuum generation. Furthermore, this also helps to shorten the start-up time of the evaporation system to some extent.

[0086] In practical applications, common low-temperature heat pump evaporators require a long time from startup to the start-up stage of steam generation, and also suffer from slow startup and low efficiency.

[0087] First, the vacuuming time is relatively long. After the evaporation system starts, a vacuum needs to be generated before wastewater can be drawn into the evaporator. In conventional systems, the water used for vacuuming in the ejector is at room temperature, and its temperature may even rise as the vacuum pump runs, making the vacuuming efficiency lower than when using cold water as the circulating water.

[0088] Secondly, the time required to heat the wastewater to its boiling point is relatively long. When the wastewater is not heated to its boiling point, water vapor cannot be generated, and there is no steam condensation on the condenser heat exchanger. Therefore, when the refrigerant vaporizes in the condenser heat exchanger, it can only absorb heat from the vacuum circulating water, which may be insufficient. This leads to a series of problems. First, it causes a lower return pressure in the first compressor, reducing its heating efficiency. A significant drop in suction pressure can even result in incomplete vaporization, causing liquid slugging in the compressor and damaging it. Second, it rapidly lowers the temperature of the vacuum circulating water. When the temperature approaches freezing point, the first compressor must be shut down; otherwise, the vacuum water pipes will freeze and crack, damaging the vacuum water pump. This means that the first compressor must wait for the water temperature to recover before it can be restarted. Sometimes, it may take multiple starts and stops of the first compressor before the wastewater boils. This defect is particularly noticeable in winter or in areas with low temperatures.

[0089] To solve the above problems, see [link to relevant documentation]. Figure 4 As shown in Figure 6, this embodiment of the application introduces a water temperature regulation system into the low-temperature heat pump evaporation equipment. This system is used to regulate the temperature of the vacuum circulating water during the liquid inlet stage and simultaneously preheat the wastewater to be treated, which helps to shorten the start-up time of the evaporation system to reach the evaporation stage. When the vacuum system reuses the circulating water tank and the circulating water used for regulating the operating conditions within the operating condition regulation system, the water temperature regulation system, in addition to regulating the circulating water temperature during the liquid inlet stage, also helps to allow the operating condition regulation system to more accurately control the heat exchange during the heating and evaporation stages, resulting in a more stable operating condition control effect.

[0090] It should be noted that when the vacuum system is an independent system, the water temperature regulation system in this embodiment can be used independently to regulate the vacuum circulating water. When the vacuum system reuses the circulating water in the operating condition regulation system, the two are integrated, and to avoid confusion, they are collectively referred to as circulating water. Since the water temperature regulation of independent vacuum circulating water is relatively simple, the reuse case is relatively more complex. The following describes the water temperature regulation system using the reuse case as an example. The temperature regulation method of independent vacuum circulating water during the liquid inlet stage can refer to the reuse case.

[0091] The required circulating water temperature for the evaporation system varies at different operating stages. During the liquid inlet stage, the circulating water needs cooling; during the heating stage, it needs heating; and during the evaporation stage, the cooling or heating of the circulating water depends on the specific operating conditions. The water temperature regulation system in this embodiment is essentially a separate heat pump system specifically designed to regulate the circulating water temperature. For ease of distinction, the refrigerant responsible for heat transfer can be referred to as a refrigerant. The water temperature regulation system can be implemented in various ways; this embodiment will exemplarily provide two implementations and describe the structure of these two exemplary water temperature regulation systems and their operating processes at different operating stages.

[0092] During the liquid inlet stage, a vacuum must first be created in the evaporator to draw wastewater into evaporator 100. Since the heat pump system for heating the wastewater has not yet started at this stage, the circulating water is not needed for heat pump system regulation; its main function is to supply the ejector 501 to create the vacuum. Based on Bernoulli's principle... It is known that, with a constant flow rate, the higher the fluid density, the lower the static pressure. In order to generate a vacuum more quickly, the circulating water needs to be at a lower temperature (e.g., around 4-10℃).

[0093] Therefore, during the liquid inlet stage, the water temperature control system operates in cooling mode. On one hand, it cools the water in the circulating water tank (e.g., to 4-10°C), improving the vacuum efficiency of the ejector; on the other hand, it preheats the wastewater in the wastewater tank, increasing the initial temperature of the wastewater before it is introduced into the evaporator through the evaporator inlet, shortening the heating time. These two aspects work together to shorten the start-up time required for the system to reach the evaporation stage.

[0094] See Figure 4 , Figure 5-1 and Figure 5-2 In the first implementation of the water temperature regulation system, the water temperature regulation system includes a main four-way valve 421, a second compressor 401, a circulating water heat exchanger 402, an air heat exchanger 403, a sewage heat exchanger 404, a second expansion valve 422, and a secondary four-way valve 423. Specifically, the first port 4211 of the main four-way valve is connected to the outlet of the second compressor 401, the second port 4212 of the main four-way valve is connected to the first interface of the circulating water heat exchanger 402, the third port 4213 of the main four-way valve is connected to the inlet of the second compressor 401, the fourth port 4214 of the main four-way valve is connected to the first interface of the sewage heat exchanger 404, the second interface of the circulating water heat exchanger 402 is connected to the first port 4231 of the auxiliary four-way valve through the second expansion valve 422, the second port 4232 of the auxiliary four-way valve is connected to the fourth port 4234 of the auxiliary four-way valve through the air heat exchanger 403, and the third port 4233 of the auxiliary four-way valve is connected to the second interface of the sewage heat exchanger 404.

[0095] This water temperature control system can operate in both heating and cooling modes. The second compressor 401 is the power source, and the main four-way valve 421 and the auxiliary four-way valve 423 are used to switch the refrigerant flow direction to achieve mode switching.

[0096] During the liquid inlet stage, see Figure 5-1The water temperature control system operates in cooling mode. The high-temperature, high-pressure gaseous refrigerant generated by the second compressor 401 passes sequentially through the first port 4211 and the fourth port 4214 of the main four-way valve, first entering the sewage heat exchanger 404 located in the sewage tank 103. The gaseous refrigerant transfers heat to the sewage on the other side of the sewage heat exchanger 404, causing the refrigerant temperature to drop and the sewage temperature to rise, thus preheating the sewage. The refrigerant then passes sequentially through the third port 4233 and the second port 4232 of the auxiliary four-way valve, entering the air heat exchanger 403. The function of the air heat exchanger 403 is to supplement the gaseous refrigerant when it has not completely condensed in the sewage heat exchanger 404, ensuring that the refrigerant is completely liquefied before entering the second expansion valve 422 and has a certain degree of subcooling. The liquid refrigerant passes through the fourth port 4234 and the first port 4231 of the auxiliary four-way valve, and then through the second expansion valve 422, entering the circulating water heat exchanger 402. Here, the liquid refrigerant absorbs heat and becomes gaseous refrigerant. The circulating water absorbs heat and its temperature decreases, achieving a cooling effect. Then, the gaseous refrigerant passes through the second port 4212 and the third port 4213 of the main four-way valve in sequence, returning to the inlet of the second compressor 401 to complete the refrigeration cycle.

[0097] During the liquid inlet stage, the control module is used to: control the second compressor 401 to be in the start state; control the first port 4211 of the main four-way valve to be connected to the fourth port 4214, and the second port 4212 to be connected to the third port 4213; and control the first port 4231 of the auxiliary four-way valve to be connected to the fourth port 4234, and the second port 4232 to be connected to the third port 4233, thereby enabling the water temperature regulation system to enter the cooling mode and reduce the circulating water temperature.

[0098] Optionally, a fifth water temperature sensor 332 is installed on the circulating water tank 302 to detect the temperature of the circulating water. When the temperature of the circulating water is lower than the minimum temperature required for the preset liquid inlet section, the control module controls the second compressor 401 to stop working.

[0099] The above-described method not only cools the circulating water and accelerates the vacuuming process, but also preheats the wastewater, thereby shortening the system's start-up time to reach the evaporation state. During wastewater preheating, the refrigerant first flows through the wastewater heat exchanger and then through the air heat exchanger. This allows the heat from the high-temperature refrigerant to be used to heat the wastewater to the maximum extent, improving the preheating effect and further shortening the system's start-up time. Furthermore, through the refrigerant's working cycle, the heat absorbed by the circulating water is transferred to the wastewater instead of being directly dissipated into the air, which also improves energy utilization.

[0100] Optionally, a fan is installed on the air heat exchanger 403. When the fan is turned on, the air flowing through the air heat exchanger 403 can achieve heat exchange between the air and the refrigerant. A fourth temperature sensor 431 and a fourth pressure sensor 432 are installed on the pipe at the outlet of the air heat exchanger 403 to detect the temperature and pressure of the refrigerant flowing out of the air heat exchanger 403, thereby determining the state of the refrigerant and the degree of subcooling.

[0101] The control module is used to: control the switching on / off of the fan of the air heat exchanger 403 based on the fourth temperature value detected by the fourth temperature sensor 431 and the fourth pressure value detected by the fourth pressure sensor 432 when the water temperature regulation system is in cooling mode. Optionally, when the refrigerant is not completely liquefied and has a target subcooling degree, the control module can control the fan to turn on, allowing the refrigerant to be completely cooled and liquefied by the air. Optionally, when the refrigerant is completely liquefied and has a target subcooling degree, the control module can control the fan to turn off.

[0102] In some possible implementations, the fan can be set to switch control or its speed can be controlled by a frequency converter. More precise control can be achieved through the control module, thereby obtaining a smooth air-cooling control effect.

[0103] After the liquid is fed in, the evaporation system enters the heating phase. During the heating phase, the heat pump system starts, and the circulating water also needs to be supplied to the operating condition regulation system to absorb or release heat. As mentioned earlier, no steam is generated in the evaporator 100 during the heating phase, and the refrigerant cannot absorb the heat from steam condensation in the condenser heat exchanger 102; it can only absorb the heat provided by the circulating water. Therefore, the system requires the circulating water to have a relatively high temperature (e.g., 25-35°C).

[0104] During the heating stage, see Figure 5-2The water temperature regulation system operates in heating mode. In the first implementation of the water temperature regulation system, the high-temperature, high-pressure gaseous refrigerant generated by the second compressor 401 passes sequentially through the first port 4211 and the second port 4212 of the main four-way valve, and first enters the circulating water heat exchanger 402 to heat the circulating water. The area of ​​the circulating water heat exchanger 402 needs to be larger than that of the wastewater heat exchanger 404 to ensure that the high-temperature gaseous refrigerant can completely release heat and condense in heating mode. At the same time, due to the high-speed flow of the circulating water, the circulating water heat exchanger 402 also has better heat exchange efficiency. After the gaseous refrigerant releases heat and liquefies, it passes through the second expansion valve 422, and sequentially through the first port 4231 and the second port 4232 of the auxiliary four-way valve, and enters the air heat exchanger 403. At this time, the function of the air heat exchanger 403 is to provide the heat required for the refrigerant to vaporize. The refrigerant is completely vaporized in the air heat exchanger 403, thus ensuring that it absorbs as little heat from the sewage as possible when it passes through the sewage heat exchanger 404. The gaseous refrigerant enters the sewage heat exchanger 404 located in the sewage tank 103 through the fourth port 4234 and the third port 4233 of the auxiliary four-way valve. Subsequently, the gaseous refrigerant returns to the inlet of the second compressor 401 through the fourth port 4214 and the third port 4213 of the main four-way valve, completing the heating cycle.

[0105] During the heating phase, the control module is used to: control the second compressor 401 to be in the start-up state; control the first port 4211 of the main four-way valve to connect to the second port 4212, and the third port 4213 to connect to the fourth port 4214; and control the first port 4231 of the auxiliary four-way valve to connect to the second port 4232, and the third port 4233 to connect to the fourth port 4234, thereby enabling the water temperature regulation system to enter the heating mode and increase the circulating water temperature. Optionally, when the circulating water temperature exceeds the preset maximum temperature required for the heating section, the control module controls the second compressor 401 to stop working.

[0106] By switching the secondary four-way valve 423, the fourth temperature sensor 431 and the fourth pressure sensor 432 remain located at the refrigerant outlet of the air heat exchanger 403. The control module is used to: determine the degree of refrigerant vaporization based on the fourth temperature value and the fourth pressure value when the water temperature regulation system is in heating mode, and control the on / off state of the fan on the air heat exchanger 403. Optionally, when the fourth temperature value has a large temperature difference from the temperature of complete vaporization (e.g., exceeding a certain preset value), the control module can determine that the refrigerant has not completely vaporized, and then control the fan on the air heat exchanger 403 to turn on. Optionally, when the refrigerant is completely vaporized, or when the fourth temperature value has only a small temperature difference from the temperature of complete vaporization (e.g., less than another preset value), the control module can control the fan on the air heat exchanger 403 to turn off.

[0107] When the wastewater in evaporator 100 is heated to its boiling point, it will boil and generate steam, at which point the evaporation system enters the evaporation stage. During the evaporation stage, the temperature of the circulating water may rise or fall depending on the operating conditions.

[0108] When steam condenses in the condenser heat exchanger 102, the refrigerant absorbs a large amount of heat released by the condensation. At this time, the circulating water needs little or no heat to supply the refrigerant. Instead, in the first heat exchanger 202 and the second heat exchanger 203, the circulating water absorbs heat from the refrigerant. In this scenario, the circulating water transitions from being the primary heat supplier during the heating phase to an auxiliary regulator. The heat released by the circulating water in the refrigerant heat exchanger 303 is less than the heat absorbed in the first and second heat exchangers 202, causing the circulating water temperature to rise. Conversely, under certain operating conditions, if the heat released in the refrigerant heat exchanger 303 is greater than the heat absorbed in the first and second heat exchangers 202, the circulating water temperature will decrease.

[0109] To maintain the circulating water temperature within a set range (e.g., 15-30℃), the water temperature control system may operate in either heating or cooling mode. When the circulating water temperature exceeds the preset maximum temperature required for the evaporation section, the control module switches the water temperature control system to cooling mode, lowering the circulating water temperature; when the water temperature drops to the set range, it shuts down the second compressor 401. When the circulating water temperature falls below the preset minimum temperature required for the evaporation section, the control module switches the water temperature control system to heating mode, raising the circulating water temperature; when the water temperature rises to the set range, it shuts down the second compressor 401.

[0110] For the first implementation of the water temperature regulation system, its structure, working process in the two modes, and the specific control method of the control module can be referred to the previous text, and will not be repeated here.

[0111] See Figure 6-1 and Figure 6-2 In the second implementation of the water temperature control system, the system includes a main four-way valve 421, a second compressor 401, a circulating water heat exchanger 402, an air heat exchanger 403, a sewage heat exchanger 404, and a second expansion valve 422. Specifically, the first port 4211 of the main four-way valve is connected to the outlet of the second compressor 401, the second port 4212 of the main four-way valve is connected to the first interface of the circulating water heat exchanger 402, the third port 4213 of the main four-way valve is connected to the inlet of the second compressor 401, and the fourth port 4214 of the main four-way valve is connected to the first interface of the sewage heat exchanger 404. The second interface of the circulating water heat exchanger 402 is connected to the second interface of the sewage heat exchanger 404 sequentially via the second expansion valve 422 and the air heat exchanger 403.

[0112] This water temperature control system also has both heating and cooling operating modes. The second compressor 401 is the power source, and the main four-way valve 421 is used to switch the refrigerant flow direction to achieve mode switching. For example... Figure 6-1 The display shows the heating mode. Figure 6-2 The diagram shows the cooling mode. The working process and main control methods of the two modes are similar to those of the first implementation method, and will not be repeated here.

[0113] Optionally, a fourth temperature sensor 431 and a fourth pressure sensor 432 may be installed between the air heat exchanger 403 and the second expansion valve 422, for example, on the pipeline at the first port of the air heat exchanger 403. Optionally, a sixth temperature sensor 433 and a sixth pressure sensor 434 may be installed between the air heat exchanger 403 and the wastewater heat exchanger 404, for example, on the pipeline at the second port of the air heat exchanger 403, to detect the temperature and pressure of the refrigerant at both ends of the air heat exchanger 403, respectively.

[0114] For example, in cooling mode, similar to the first implementation described above, the air heat exchanger 403 is used to completely liquefy the refrigerant and achieve a certain degree of subcooling to obtain a better expansion effect. By detecting the temperature and pressure of the refrigerant (i.e., the fourth temperature sensor 431 and the fourth pressure sensor 432) located before the second expansion valve 422 and after the air heat exchanger 403, it can be determined whether the refrigerant is completely liquefied. If it is not completely liquefied, the control module controls the fan of the air heat exchanger 403 to turn on; when the refrigerant is completely liquefied and has the target subcooling, the control module can control the fan to turn off.

[0115] For example, in heating mode, setting and controlling the air heat exchanger 403 can be used to prevent excessive heat loss from the wastewater in the wastewater tank 103. By detecting the refrigerant temperature and pressure (i.e., the sixth temperature value and the sixth pressure value) using sensors (i.e., the sixth temperature sensor 433 and the sixth pressure sensor 434) after the air heat exchanger 403 and before the wastewater heat exchanger 404, it can be determined whether the refrigerant has completely vaporized. If it has not completely vaporized, or if there is a significant temperature difference from the temperature required for complete vaporization, the control module turns on the fan of the air heat exchanger 403; if it has completely vaporized, the fan is turned off.

[0116] It should be noted that the various possible implementations of the water temperature regulation system of this application can be used individually in low-temperature heat pump evaporation equipment to regulate the water temperature of vacuum circulating water, or they can be used to regulate the water temperature of circulating water in other possible operating condition regulation systems, for example as follows: Figure 7 or Figure 8 As shown, it is not required that the aforementioned operating condition regulation system architecture, which includes three regulating valves, a first heat exchanger, and a second heat exchanger, be used as a prerequisite.

[0117] As mentioned earlier, the condenser heat exchanger 102 can be a shell-and-tube heat exchanger, in which case the shell-and-tube heat exchanger can replace the function of the refrigerant heat exchange device in the operating condition regulation system. See Figures 9 to 11 The shell-and-tube heat exchanger includes an inner tube 1021 and an outer tube 1022. The diameter of the inner tube 1021 is smaller than that of the outer tube 1022. The inner tube 1021 is nested inside the outer tube 1022, thus isolating the space within the inner tube 1021 and the space between the inner tube 1021 and the outer tube 1022, which respectively serve as components of the circulating water circuit and the heat pump circuit. The first outlet 3211 of the first regulating valve 321 is connected to the inlet 3223 of the second regulating valve 322 through the inner tube 1021; the first expansion valve 221 is connected to the inlet of the first compressor 201 through the outer tube 1022.

[0118] Vacuum systems typically require ejectors and circulating water for evacuation. During the operation of a low-temperature heat pump evaporator, the temperature of the circulating water may rise, affecting the efficiency of the ejector. A conventional solution is to install an additional water-cooling system or connect a separate heat exchanger in parallel or series with the main heat pump loop of the evaporator. In this heat exchanger, the refrigerant in the main heat pump loop exchanges heat with the circulating water, thereby cooling the circulating water. This results in a relatively complex and costly structure for the low-temperature heat pump evaporator, and the parallel or series connection of heat exchangers can easily affect the operation of the main heat pump loop. Using this approach, circulating water can flow in the inner tube of the condensing heat exchanger, and refrigerant flows between the inner and outer tubes. Simultaneously, the outer wall of the outer tube is exposed to the steam generated by the evaporator, directly contacting the steam. Therefore, a co-type heat exchanger can simultaneously achieve the dual functions of heat exchange between the refrigerant and circulating water, and between the refrigerant and the steam in the evaporator. This allows the refrigerant to cool the circulating water, thereby improving the efficiency of the ejector. Simultaneously, the heat from the circulating water can replenish the refrigerant's heat when there is no steam or very little steam in the system, further enhancing heat exchange efficiency. Furthermore, this design makes the low-temperature heat pump evaporator more compact, eliminating the need for an additional water-cooling system or a separate heat exchanger for circulating water cooling. This reduces equipment complexity and cost, and also avoids any impact on the main heat pump loop.

[0119] It can be understood that when a shell-and-tube heat exchanger is used, other possible components in the low-temperature heat pump evaporation equipment of this application embodiment can be combined with any of the aforementioned non-contradictory implementation methods.

[0120] It is understood that the heat pump low-temperature evaporation equipment may also include other possible components, and in actual use it may also be connected to other possible components, modules, systems, etc., which is not limited in this application.

[0121] It should be understood that in the description of this application, the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," and "outer," etc., generally indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These directions and positional relationships are for ease of description and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0122] It should also be understood that, unless otherwise explicitly specified, the terms "installation," "connection," "assembly," "fixing," etc., in the description of this application should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0123] It should also be understood that, unless otherwise explicitly specified, "multiple" means two or more.

[0124] The same or similar parts among the various embodiments in this specification can be referred to interchangeably. Different implementations in the above embodiments can be combined with each other as long as they do not contradict each other. The above implementation methods do not constitute a limitation on the scope of protection of this application.

Claims

1. A low-temperature heat pump evaporation device, characterized in that, This includes an evaporation system, a heat pump system, a vacuum system, and an operating condition control system; among which, The evaporation system includes an evaporator, an evaporation heat exchanger, and a condensation heat exchanger. The evaporation heat exchanger is used to provide the heat required for evaporation of the liquid in the evaporator, and the condensation heat exchanger is used to provide a condensation environment for the gas evaporated in the evaporator. The heat pump system includes a first compressor, a first heat exchanger, a second heat exchanger, a first expansion valve, and a refrigerant heat exchange device; the outlet of the first compressor is connected to the inlet of the first compressor in sequence through the first heat exchanger, the evaporator heat exchanger, the second heat exchanger, the first expansion valve, the condenser heat exchanger, and the refrigerant heat exchange device to form a heat pump circuit; The vacuum system is used to provide a vacuum environment for the evaporation system; The operating condition regulation system includes a circulating water tank, a first circulating water pump, a first regulating valve, a second regulating valve, and a third regulating valve. The lower part of the circulating water tank is connected to the inlet of the first circulating water pump, and the outlet of the first circulating water pump is connected to the inlet of the first regulating valve. The first outlet of the first regulating valve is connected to the inlet of the second regulating valve through the refrigerant heat exchanger, for heat exchange with the refrigerant flowing through the refrigerant heat exchanger. The second outlet of the first regulating valve is connected to the inlet of the second regulating valve, and the first outlet of the second regulating valve is connected to the inlet of the third regulating valve through the second heat exchanger. The first outlet of the third regulating valve is connected to the inlet of the circulating water tank through the first heat exchanger, and the second outlet of the third regulating valve is connected to the first inlet of the circulating water tank, forming an operating condition regulation loop.

2. The low-temperature heat pump evaporation equipment according to claim 1, characterized in that, The low-temperature heat pump evaporation equipment also includes a control module; A third temperature sensor and a third pressure sensor are provided at the refrigerant outlet of the refrigerant heat exchange device; the control module is used to: adjust the opening degree of the first outlet of the first regulating valve according to the third temperature value detected by the third temperature sensor and the third pressure value detected by the third pressure sensor during the heating and / or evaporation stage. And / or, A second temperature sensor and a second pressure sensor are provided at the refrigerant outlet of the second heat exchanger; the control module is used to: during the heating and / or evaporation stage, adjust the opening of the first outlet of the second regulating valve according to the second temperature value detected by the second temperature sensor and the second pressure value detected by the second pressure sensor; And / or, A first temperature sensor and a first pressure sensor are provided at the refrigerant outlet of the first heat exchanger; the control module is used to: during the heating and / or evaporation stage, adjust the opening of the first outlet of the third regulating valve according to the first temperature value detected by the first temperature sensor and the first pressure value detected by the first pressure sensor; And / or, The control module is also used to: during the liquid inlet phase, control the first outlet of the first regulating valve, the first outlet of the second regulating valve, and the first outlet of the third regulating valve to be in a closed state.

3. The low-temperature heat pump evaporation equipment according to any one of claims 1 to 2, characterized in that, The vacuum system includes an ejector, the first inlet of which is connected to the outlet of the first circulating water pump, the outlet of which is connected to the inlet of the first regulating valve, and the second inlet of which is connected to the evaporator; or, The vacuum system includes an ejector and a second circulating water pump; the lower part of the circulating water tank is connected to the inlet of the second circulating water pump, the outlet of the second circulating water pump is connected to the first inlet of the ejector, the outlet of the ejector is connected to the second inlet of the circulating water tank, and the second inlet of the ejector is connected to the evaporator.

4. The low-temperature heat pump evaporation equipment according to any one of claims 1 to 3, characterized in that, The low-temperature heat pump evaporation equipment also includes a water temperature regulation system, which is used for: During the liquid inlet stage, the water in the circulating water tank is cooled, and the wastewater to be treated in the wastewater tank connected to the inlet of the evaporator is preheated; and / or, During the heating phase, the water in the circulating water tank is heated; and / or, During the evaporation stage, the water in the circulating water tank is cooled or heated.

5. The low-temperature heat pump evaporation equipment according to claim 4, characterized in that, The water temperature regulation system includes a main four-way valve, a second compressor, a circulating water heat exchanger, an air heat exchanger, a sewage heat exchanger, a second expansion valve, and a secondary four-way valve. The main four-way valve has its first port connected to the outlet of the second compressor, its second port connected to the first interface of the circulating water heat exchanger, its third port connected to the inlet of the second compressor, its fourth port connected to the first interface of the wastewater heat exchanger, the second interface of the circulating water heat exchanger connected to the first port of the auxiliary four-way valve via the second expansion valve, the second port of the auxiliary four-way valve connected to the fourth port of the auxiliary four-way valve via the air heat exchanger, and its third port connected to the second interface of the wastewater heat exchanger.

6. The low-temperature heat pump evaporation equipment according to claim 5, characterized in that, The control module is used to control the water temperature regulation system to enter the cooling mode, including: controlling the second compressor to be in the start state; controlling the first interface of the main four-way valve to connect to the fourth interface and the second interface to connect to the third interface; and controlling the first interface of the auxiliary four-way valve to connect to the fourth interface and the second interface to connect to the third interface. or, The control module is used to control the water temperature regulation system to enter the heating mode, including: controlling the second compressor to be in the start state; controlling the first interface of the main four-way valve to connect to the second interface and the third interface to connect to the fourth interface; and controlling the first interface of the auxiliary four-way valve to connect to the second interface and the third interface to connect to the fourth interface.

7. The low-temperature heat pump evaporation equipment according to claim 6, characterized in that, A fourth temperature sensor and a fourth pressure sensor are installed at the outlet of the air heat exchanger; The control module is used to: determine the degree of liquefaction and subcooling of the refrigerant at the outlet of the air heat exchanger based on the fourth temperature value detected by the fourth temperature sensor and the fourth pressure value detected by the fourth pressure sensor when the water temperature regulation system is in cooling mode, and control the on / off switch of the fan of the air heat exchanger. When the water temperature regulation system is in heating mode, the degree of vaporization of the refrigerant is determined based on the fourth temperature value and the fourth pressure value, and the fan of the air heat exchanger is switched on and off.

8. The low-temperature heat pump evaporation equipment according to claim 4, characterized in that, The water temperature regulation system includes a main four-way valve, a second compressor, a circulating water heat exchanger, an air heat exchanger, a sewage heat exchanger, and a second expansion valve. The first port of the main four-way valve is connected to the outlet of the second compressor, the second port of the main four-way valve is connected to the first interface of the circulating water heat exchanger, the third port of the main four-way valve is connected to the inlet of the second compressor, the fourth port of the main four-way valve is connected to the first interface of the sewage heat exchanger, and the second interface of the circulating water heat exchanger is connected to the second expansion valve, the air heat exchanger and the second interface of the sewage heat exchanger in sequence.

9. The low-temperature heat pump evaporation equipment according to claim 8, characterized in that, A fourth temperature sensor and a fourth pressure sensor are provided between the air heat exchanger and the second expansion valve; a sixth temperature sensor and a sixth pressure sensor are provided between the air heat exchanger and the wastewater heat exchanger. The control module is used to: determine the degree of liquefaction and subcooling of the refrigerant at the outlet of the air heat exchanger based on the fourth temperature value detected by the fourth temperature sensor and the fourth pressure value detected by the fourth pressure sensor when the water temperature regulation system is in cooling mode, and control the on / off switch of the fan of the air heat exchanger. When the water temperature regulation system is in heating mode, the degree of refrigerant vaporization at the outlet of the air heat exchanger is determined based on the sixth temperature value detected by the sixth temperature sensor and the sixth pressure value detected by the sixth pressure sensor, and the fan of the air heat exchanger is switched on and off.

10. The low-temperature heat pump evaporation equipment according to any one of claims 1 to 9, characterized in that, The condenser heat exchanger is a shell-and-tube heat exchanger, replacing the refrigerant heat exchange device; wherein, The first outlet of the first regulating valve is connected to the inlet of the second regulating valve through the inner tube of the condenser heat exchanger; The first expansion valve is connected to the inlet of the first compressor through the outer pipe of the condenser heat exchanger.

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