A compressor lubricating oil waste heat recovery type water preheating device

Abstract

This utility model relates to the field of heat pump and industrial steam supply technology, specifically to a compressor lubricating oil waste heat recovery type water preheating device, including a refrigerant circulation loop, a lubricating oil circulation loop, and a water preheating loop; the refrigerant circulation loop includes a refrigerant circulation route and an oil separation route, the refrigerant circulation route exchanges heat with the water preheating loop, the oil separation route includes a compressor and an oil-gas separator, the inlet of the oil-gas separator is connected to the outlet of the compressor for separating the refrigerant and the lubricating oil; this utility model, by setting up a water preheater, preheats the water before it enters the condenser, reduces the temperature difference between the low-temperature water and the high-temperature refrigerant, improves the heat exchange conditions of the condenser, and at the same time uses the cooling waste heat of the compressor lubricating oil during the circulation process to heat the water, realizing the recovery of lubricating oil waste heat and avoiding the direct loss of lubricating oil waste heat to the environment or cooling medium.

Description

Technical Field

[0001] This utility model relates to the field of heat pump and industrial steam supply technology, specifically to a compressor lubricating oil waste heat recovery type water preheating device. Background Technology

[0002] With the increasing demand for clean steam in the industrial sector, high-temperature heat pump steam generation systems are gradually being applied to process gas scenarios in industries such as food, chemical and brewing due to their characteristics of being driven by electricity and having no direct combustion emissions. Existing high-temperature heat pump steam generation systems typically include components such as compressors, condensers, evaporators and gas-liquid separation devices, which achieve water heating and vaporization by releasing heat on the condenser side of the refrigerant.

[0003] In existing technologies, system makeup water typically enters the condenser directly, exchanging heat with the refrigerant which is under high temperature and pressure. Because the makeup water temperature is usually low, a significant temperature difference exists between the low-temperature makeup water and the high-temperature refrigerant, easily leading to an increase in the average heat exchange temperature on the condenser side. This increases the system's condensing pressure, thereby increasing the compressor's operating load and negatively impacting system energy efficiency and stable operation. Furthermore, during compressor operation, lubricating oil is used to lubricate and cool internal moving parts, carrying residual heat during circulation. In existing systems, this residual heat from the lubricating oil is mostly released directly to the environment or cooling medium through the oil cooler, failing to achieve effective recovery and utilization.

[0004] Therefore, how to make reasonable use of the cooling waste heat of the compressor lubricating oil to preheat the system makeup water without changing the basic structure and operation mode of the existing high-temperature heat pump steam generation system has become a technical problem that urgently needs to be solved in this field. Utility Model Content

[0005] The purpose of this invention is to address the problems in existing high-temperature heat pump steam generation systems, such as the fact that makeup water usually enters the condenser directly to exchange heat with the high-temperature refrigerant, the large temperature difference between the low-temperature makeup water and the high-temperature heat source, the high operating pressure on the condenser side, and the ineffective utilization of the waste heat from the compressor lubricating oil. This invention provides a compressor lubricating oil waste heat recovery type makeup water preheating device to solve the above problems.

[0006] This utility model is achieved through the following technical solution:

[0007] A compressor lubricating oil waste heat recovery type water preheating device includes a refrigerant circulation loop, a lubricating oil circulation loop, and a water preheating loop. The refrigerant circulation loop includes a refrigerant circulation path and an oil separation path. The refrigerant circulation path exchanges heat with the water preheating loop. The oil separation path includes a compressor and an oil-gas separator. The compressor has a first inlet, a second inlet, and an outlet. The first inlet of the compressor is connected to the refrigerant circulation path, and the second inlet of the compressor is connected to the lubricating oil circulation loop. The oil-gas separator has an inlet, a first outlet, and a second outlet. The inlet of the oil-gas separator is connected to the outlet of the compressor for... The refrigerant and lubricating oil are separated. The first outlet of the oil-gas separator is connected to the refrigeration cycle route for heat exchange of the refrigerant. The second outlet of the oil-gas separator is connected to the lubricating oil cycle route for heat exchange of the lubricating oil. The water in the makeup water cycle route exchanges heat with the lubricating oil in the lubricating oil cycle route and the refrigerant in the refrigerant cycle route, respectively. The refrigerant cycle route includes an evaporator, a condenser, and a throttling device, which are connected in sequence. The outlet of the evaporator is connected to the first inlet of the compressor. The inlet of the condenser is connected to the first outlet of the oil-gas separator, and the condenser exchanges heat with the water in the makeup water cycle route.

[0008] Compared with the existing method of directly introducing makeup water into the condenser for heat exchange, in this application the makeup water is first preheated by the residual heat of lubricating oil, which significantly reduces the temperature difference between the makeup water and the refrigerant condensation heat release side, improves the heat exchange conditions on the condensation side, and helps to reduce the condensation pressure of the device and improve the overall energy efficiency.

[0009] Preferably, the lubricating oil circulation loop includes a water preheater, an oil cooler, an oil filter, a bypass valve, an oil cooling branch valve, a temperature sensor I, and a temperature sensor III. The inlet of the water preheater is connected to the second outlet of the oil-gas separator. A temperature sensor I for monitoring the lubricating oil temperature is installed on the connecting pipe between the oil-gas separator and the water preheater. The outlet of the water preheater is connected to a first pipe and a second pipe via a tee fitting. The first pipe is connected to the inlet of the oil cooler, and the second pipe is connected in series with the outlet of the oil cooler and the inlet of the oil filter. The oil cooler and the oil filter are connected via a pipe, and the outlet of the oil filter is connected to the second inlet of the compressor for replenishing the lubricating oil.

[0010] Preferably, a temperature sensor III for monitoring the lubricating oil temperature is installed on the connecting pipe between the water preheater and the tee fitting, an oil cooling branch valve for controlling the flow of lubricating oil is installed on the first pipe, and a bypass valve for controlling the flow of lubricating oil is installed on the second pipe.

[0011] Preferably, the water preheater undergoes a first heat exchange with the water in the water replenishment circulation loop.

[0012] Preferably, the water replenishment circulation loop includes a water replenishment pump, a circulating water pump, a gas-liquid separator, a steam valve, and a temperature sensor II. The outlet of the water replenishment pump is provided with a first heat exchange pipe, and the water in the first heat exchange pipe exchanges heat with the lubricating oil circulation loop.

[0013] Preferably, the first heat exchange tube is connected to a gas-liquid separator, which includes a liquid storage area and a gas-liquid separation area. The inlet of the liquid storage area of ​​the gas-liquid separator is connected to the first heat exchange tube. A temperature sensor II for monitoring water temperature is installed on the connecting pipe between the liquid storage area and the first heat exchange tube. A second heat exchange tube is connected to the outlet of the liquid storage area. A circulating water pump for water circulation is installed on the connecting pipe between the second heat exchange tube and the liquid storage area.

[0014] Preferably, the gas-liquid separation zone of the gas-liquid separator is provided with a steam outlet, a hot water outlet and an inlet. The inlet is connected to the second heat exchange tube, the hot water outlet is connected to the liquid storage zone, and an exhaust pipe is provided at the steam outlet. A steam valve for controlling the steam discharge is provided on the exhaust pipe.

[0015] Preferably, the water preheater is a double-walled plate heat exchanger.

[0016] Preferably, the throttling device, bypass valve, and oil cooling branch valve are all electronic expansion valves or capillary valves.

[0017] Compared with the prior art, this utility model has the following advantages and beneficial effects:

[0018] 1. This utility model, by setting up a water preheater, preheats the water before it enters the condenser, reducing the temperature difference between the low-temperature water and the high-temperature refrigerant, which is beneficial to improving the heat exchange conditions of the condenser. At the same time, it uses the residual heat of the compressor lubricating oil during the circulation process to heat the water, realizing the recovery and utilization of the residual heat of the lubricating oil, and avoiding the direct loss of the residual heat of the lubricating oil to the environment or the cooling medium.

[0019] 2. Without changing the basic structure of the high-temperature heat pump steam generator, this utility model helps to reduce the condensing pressure of the device and the operating load of the compressor by adding a water preheating stage, thereby improving the stability of the device operation.

[0020] 3. This utility model has a simple structure and flexible layout, and is easy to integrate and apply in existing high-temperature heat pump steam generation systems, thus having good engineering practicality. Attached Figure Description

[0021] The accompanying drawings, which are included to provide a further understanding of the embodiments of the present invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0022] Figure 1 This is a schematic diagram of the overall structure of this utility model.

[0023] The attached diagram shows the markings and corresponding component names:

[0024] 1-Evaporator; 2-Compressor; 3-Oil-gas separator; 4-Water preheater; 5-Oil cooler; 6-Oil filter; 7-Water pump; 8-Circulating water pump; 9-Gas-liquid separator; 10-Steam valve; 11-Condenser; 12-Throttling device; 13-Bypass valve; 14-Oil cooling branch valve; 15-Temperature sensor I; 16-Temperature sensor II; 17-Temperature sensor III. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this utility model clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this utility model are for explaining the utility model only and are not intended to limit the utility model. It should be noted that this utility model is already in the actual research and development stage.

[0026] Example 1

[0027] like Figure 1 As shown, in this embodiment, a compressor lubricating oil waste heat recovery type water preheating device is provided, including a refrigerant circulation loop, a lubricating oil circulation loop, and a water preheating loop. The refrigerant circulation loop includes a refrigerant circulation route and an oil separation route. The refrigerant circulation route exchanges heat with the water preheating loop. The oil separation route includes a compressor 2 and an oil-gas separator 3. The compressor 2 is provided with a first inlet, a second inlet, and an outlet. The first inlet of the compressor 2 is connected to the refrigerant circulation route, and the second inlet of the compressor 2 is connected to the lubricating oil circulation loop. The oil-gas separator 3 is provided with an inlet, a first outlet, and a second outlet. The inlet of the oil-gas separator 3 is connected to the outlet of the compressor 2 for the separation of refrigerant and lubricating oil. The first outlet of the oil-gas separator 3 is connected to the refrigerant circulation route for heat exchange of the refrigerant, and the second outlet of the oil-gas separator 3 is connected to the lubricating oil circulation loop for heat exchange of the lubricating oil. The water in the water preheating loop exchanges heat with the lubricating oil in the lubricating oil circulation loop and the refrigerant in the refrigerant circulation loop, respectively.

[0028] The refrigerant circulation loop includes an evaporator 1, a compressor 2, an oil-gas separator 3, a condenser 11, and a throttling device 12. The condenser 11, the throttling device 12, and the evaporator 1 are connected in sequence. The outlet of the evaporator 1 is connected to the first inlet of the compressor 2 through a pipe. The outlet of the compressor 2 is connected to the inlet of the oil-gas separator 3 through a connecting pipe. The first outlet of the oil-gas separator 3 is connected to the inlet of the condenser 11 through a connecting pipe. The second outlet of the oil-gas separator 3 is connected to the inlet of the water preheater 4 in the lubricating oil circulation loop through a pipe. The condenser 11 undergoes a second heat exchange with the water in the water circulation loop.

[0029] The lubricating oil circulation loop includes a water preheater 4, an oil cooler 5, an oil filter 6, a bypass valve 13, an oil cooling branch valve 14, a temperature sensor I 15, and a temperature sensor III 17. A temperature sensor I 15 is installed on the connecting pipe between the oil-gas separator 3 and the water preheater 4 to detect the temperature of the lubricating oil before it enters the water preheater 4. The outlet of the water preheater 4 is connected to a first pipe and a second pipe via a tee fitting. The first pipe is connected to the inlet of the oil cooler 5, and the second pipe is connected in series with the outlet of the oil cooler 5 and the inlet of the oil filter 6. The oil cooler 5 and the oil filter 6 are connected via... The pipeline is connected, and the outlet of the oil filter 6 is connected to the second inlet of the compressor 2 for the return replenishment of lubricating oil. A temperature sensor Ⅲ17 for monitoring the lubricating oil temperature is installed on the connecting pipe between the water preheater 4 and the three-way fitting. An oil cooling branch valve 14 for controlling the passage of lubricating oil is installed on the first pipeline, and a bypass valve 13 for controlling the passage of lubricating oil is installed on the second pipeline. The water preheater 4 performs the first heat exchange with the water in the water circulation loop, raising the initial temperature of the water, so that the temperature difference between the water entering the condenser 11 and the refrigerant temperature in the condenser 11 is reduced, thereby reducing the heat load of the condenser 11.

[0030] The water preheater 4 adopts a double-walled plate heat exchanger, forming a tiny leakage guide gap between the double-walled plates. If corrosion or pressure rupture occurs, lubricating oil or water will preferentially seep into this gap and flow out from the drain hole on the outside of the water preheater 4, thereby achieving physical isolation and visual alarm, preventing internal oil-water leakage, and ensuring the cleanliness of the water supply circuit. The water preheater 4 is sealed with full welding or high-strength brazing. Considering the high discharge pressure of the compressor 2, the inflow pressure requirement of the water preheater 4 is not lower than the design pressure of the high-pressure side of the system. The outflow pressure of the water preheater 4 is determined according to the head of the water pump 7. When designing the heat exchange area, the allowable pressure difference between the two ends of the water preheater 4 is controlled within a reasonable range (e.g., the pressure drop on the lubricating oil side ≤ 50 kPa of the oil cooler) to ensure that the lubricating oil still has sufficient pressure to overcome the resistance of the pipeline and the oil cooler 5 after releasing residual heat and flows smoothly back to the compressor 2.

[0031] The water replenishment circulation loop includes a water replenishment pump 7, a circulating water pump 8, a gas-liquid separator 9, a steam valve 10, and a temperature sensor II 16. The inlet of the water replenishment pump 7 is connected to an external water source, and the outlet of the water replenishment pump 7 is equipped with a first heat exchange pipe. The first heat exchange pipe passes through the interior of the water replenishment preheater 4, where the water in the first heat exchange pipe exchanges heat with the lubricating oil in the water replenishment preheater 4. The first heat exchange pipe is connected to the gas-liquid separator 9, which includes a liquid storage area and a gas-liquid separation area. The inlet of the liquid storage area is connected to the first heat exchange pipe via a connecting pipe. A temperature sensor II 16 for monitoring water temperature is installed on the connecting pipe between the liquid storage area and the first heat exchange pipe. The outlet of the liquid storage area is connected to... A second heat exchange tube is installed through the connecting pipe. The second heat exchange tube passes through the interior of the condenser 11. The water in the second heat exchange tube exchanges heat with the refrigerant in the condenser 11. A circulating water pump 8 for water circulation is installed on the connecting pipe between the second heat exchange tube and the liquid storage area. The gas-liquid separation zone of the gas-liquid separator 9 is provided with a steam outlet, a hot water outlet and an inlet. The inlet is connected to the second heat exchange tube, and the hot water outlet is connected to the liquid storage area. An exhaust pipe is provided at the steam outlet. A steam valve 10 for controlling the steam discharge is installed on the exhaust pipe. The valve types used in the throttling device 12, bypass valve 13 and oil cooling branch valve 14 are all electronic expansion valves or capillary tubes.

[0032] Example 2

[0033] like Figure 1 As shown in this embodiment, a working principle of a compressor lubricating oil waste heat recovery type water preheating device is provided. During operation, the compressor 2 adopts an oil-injection structure. During the compression process, lubricating oil is directly injected into the compression chamber for lubrication, sealing and cooling. The working fluid discharged by the compressor 2 is a mixture of high-temperature and high-pressure refrigerant and lubricating oil. The mixture first enters the oil-gas separator 3, where the refrigerant and lubricating oil are effectively separated. The separated refrigerant enters the condenser 11 to release heat and condense. The condensed refrigerant is stably input into the evaporator 1 through the throttling device 12 and evaporates through the evaporator 1 before entering the compressor 2 to complete the refrigerant cycle.

[0034] The lubricating oil separated by the oil-gas separator 3 enters the lubricating oil circulation loop. The water preheater 4 serves as a heat exchange device between the lubricating oil circulation loop and the water preheater loop. It utilizes the residual heat carried by the lubricating oil during the compression process and the oil-gas separation process to preheat the water entering the system, so that the water is already in a medium-high temperature state before entering the gas-liquid separator 9. The lubricating oil separated by the oil-gas separator 3 enters the water preheater 4 to release heat. The water in the first exchange pipe of the water circulation loop exchanges heat with the lubricating oil in the water preheater 4 for preheating.

[0035] After heat exchange is completed, the flow direction of the lubricating oil is selected by the bypass valve 13 and the oil cooling branch valve 14 according to the operating conditions. When the lubricating oil temperature is too high and does not meet the return oil temperature requirements of the compressor 2, the bypass valve 13 is closed and the oil cooling branch valve 14 is opened. After being cooled by the oil cooler 5, the lubricating oil is filtered by the oil filter 6 and finally flows back to the compressor 2.

[0036] When the lubricating oil temperature meets the return oil requirements of compressor 2, the bypass valve 13 is opened and the oil cooling branch valve 14 is closed. The lubricating oil bypasses the oil cooler 5 and is directly filtered through the oil filter 6 before finally flowing back into compressor 2, reducing unnecessary cooling losses.

[0037] During water replenishment, water is pumped into the water circulation loop by the water replenishment pump 7 and enters the first heat exchange tube. The lubricating oil in the water replenishment preheater 4 exchanges heat with the water in the first heat exchange tube to preheat the water. The preheated water enters the storage area of ​​the gas-liquid separator 9. The water in the storage area is pumped into the second heat exchange tube by the circulating water pump 8. The water in the second heat exchange tube exchanges heat with the refrigerant in the condenser 11 to generate high-temperature and high-pressure steam, which further enters the gas-liquid separation area of ​​the gas-liquid separator 9. The gas-liquid separation area of ​​the gas-liquid separator 9 effectively separates the gas and liquid. The separated steam is discharged as high-temperature steam by the steam valve 10. The separated water is circulated and stored in the storage area of ​​the gas-liquid separator 9 to await the next water replenishment cycle.

[0038] Temperature sensors I15, II16, and III17 are installed in the lubricating oil circulation loop and the water replenishment circulation loop to detect the temperature of the medium at key locations. Temperature sensor I15 is installed on the connecting pipe before the lubricating oil enters the water replenishment preheater 4 to detect the temperature of the lubricating oil before entering the preheater. Temperature sensor II16 is installed on the connecting pipe between the first heat exchange pipe and the liquid storage area of ​​the gas-liquid separator 9 to detect the temperature of the water after preheating. Temperature sensor III17 is installed on the connecting pipe between the water replenishment preheater 4 and the tee fitting to detect the temperature of the lubricating oil when it enters the tee fitting. Temperature sensors I15, II16, and III17 are connected to the control unit (not shown in the figure) to provide temperature information for selecting the lubricating oil path. The control unit is set with temperature threshold ranges corresponding to the temperature sensors to determine the lubricating oil temperature within a range. The control unit also includes a delay control module to prevent frequent valve switching, maintaining a preset time after valve switching. The control unit is also equipped with an abnormal protection structure. When an abnormal temperature sensor signal or valve execution is detected, the bypass valve or oil cooling branch valve is controlled to be in a preset safety state to ensure that the lubricating oil return temperature meets the compressor's operating requirements.

[0039] Example 3

[0040] like Figure 1 As shown in this embodiment, the beneficial effects of a compressor lubricating oil waste heat recovery type water preheating device are as follows: After the water preheater 4 is preheated, it absorbs the cooling heat of the lubricating oil, and the water temperature can be increased by about 20 to 40°C compared with the unpreheated state. This preheating process replaces part of the original sensible heat heating load of the condenser 11, thereby increasing the effective heat exchange available for water vaporization phase change in the condenser 11. Under the condition that the input power of the compressor 2 remains basically unchanged, the effective heating capacity (steam output) of the system is significantly increased, and the coefficient of performance (COP) of the whole system is increased by about 5% to 12%.

[0041] Under variable operating conditions such as fluctuations in water supply flow or changes in steam load, the matching relationship between the heat generation of lubricating oil and the system load may deviate, which can easily cause runaway oil return temperature. This device monitors the oil temperature in real time through the control unit and dynamically switches the bypass valve 13 and the oil cooling branch valve 14 in combination with the hysteresis control strategy. When the oil temperature approaches the preset upper limit, it automatically introduces oil cooler 5 for forced cooling in proportion. This control logic strictly stabilizes the compressor oil return temperature within the preset safe range (e.g., 45℃~55℃), effectively smoothing out the peak fluctuations in oil temperature caused by sudden load changes, avoiding lubrication failure due to excessively high oil temperature or refrigerant carryover due to excessively low oil temperature, and greatly improving the operational reliability of the system under complex operating conditions.

[0042] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A compressor lubricating oil waste heat recovery type water preheating device, characterized in that: It includes a refrigerant circulation loop, a lubricating oil circulation loop, and a water replenishment circulation loop; the refrigerant circulation loop includes a refrigerant circulation route and an oil separation route, the refrigerant circulation route exchanges heat with the water replenishment circulation loop, the oil separation route includes a compressor (2) and an oil-gas separator (3), the compressor (2) is provided with a first inlet, a second inlet and an outlet, the first inlet of the compressor (2) is connected to the refrigerant circulation route, the second inlet of the compressor (2) is connected to the lubricating oil circulation loop, the oil-gas separator (3) is provided with an inlet, a first outlet and a second outlet, the inlet of the oil-gas separator (3) is connected to the outlet of the compressor (2) for the separation of refrigerant and lubricating oil, the first outlet of the oil-gas separator (3) is connected to the refrigerant circulation route for heat exchange of refrigerant, the second outlet of the oil-gas separator (3) is connected to the lubricating oil circulation loop for heat exchange of lubricating oil, and the water in the water replenishment circulation loop exchanges heat with the lubricating oil in the lubricating oil circulation loop and the refrigerant in the refrigerant circulation loop.

2. A water supplement preheating device of a compressor lubricating oil waste heat recovery type according to claim 1, characterized in that: The refrigerant circulation route includes an evaporator (1), a condenser (11), and a throttling device (12). The condenser (11), the throttling device (12), and the evaporator (1) are connected in sequence. The outlet of the evaporator (1) is connected to the first inlet of the compressor (2). The inlet of the condenser (11) is connected to the first outlet of the oil-gas separator (3). The condenser (11) undergoes a second heat exchange with the water in the water replenishment circulation loop.

3. The water supplement preheating device of claim 1, wherein the water supplement preheating device is characterized by: The lubricating oil circulation loop includes a water preheater (4), an oil cooler (5), an oil filter (6), a bypass valve (13), an oil cooling branch valve (14), a temperature sensor I (15), and a temperature sensor III (17). The inlet of the water preheater (4) is connected to the second outlet of the oil-gas separator (3). A temperature sensor I (15) for monitoring the lubricating oil temperature is installed on the connecting pipe between the oil-gas separator (3) and the water preheater (4). The outlet of the water preheater (4) is connected to the first pipe and the second pipe through a three-way fitting. The first pipe is connected to the inlet of the oil cooler (5). The second pipe is connected in series with the outlet of the oil cooler (5) and the inlet of the oil filter (6). The oil cooler (5) and the oil filter (6) are connected through a pipe. The outlet of the oil filter (6) is connected to the second inlet of the compressor (2) for replenishing the lubricating oil.

4. The water supplement preheating device of claim 3, wherein the water supplement preheating device is characterized by: The water preheater (4) and the connecting pipe of the three-way fitting are equipped with a temperature sensor Ⅲ (17) for monitoring the temperature of the lubricating oil. The first pipe is equipped with an oil cooling branch valve (14) for controlling the passage of lubricating oil, and the second pipe is equipped with a bypass valve (13) for controlling the passage of lubricating oil.

5. The water supplement preheating device of claim 3, wherein the water supplement preheating device is characterized by: The water preheater (4) exchanges heat with the water in the water replenishment circulation loop for the first time.

6. The water supplement preheating device of claim 1, wherein the water supplement preheating device is characterized by: The water replenishment circulation loop includes a water replenishment pump (7), a circulating water pump (8), a gas-liquid separator (9), a steam valve (10), and a temperature sensor II (16). The outlet of the water replenishment pump (7) is provided with a first heat exchange pipe, and the water in the first heat exchange pipe exchanges heat with the lubricating oil circulation loop.

7. The water supplement preheating device of claim 6, wherein the water supplement preheating device is characterized by: The first heat exchange tube is connected to the gas-liquid separator (9). The gas-liquid separator (9) includes a liquid storage area and a gas-liquid separation area. The inlet of the liquid storage area of ​​the gas-liquid separator (9) is connected to the first heat exchange tube. A temperature sensor II (16) for monitoring water temperature is installed on the connecting pipe between the liquid storage area and the first heat exchange tube. A second heat exchange tube is connected to the outlet of the liquid storage area. A circulating water pump (8) for water circulation is installed on the connecting pipe between the second heat exchange tube and the liquid storage area.

8. The water supplement preheating device of claim 7, wherein the water supplement preheating device is characterized by: The gas-liquid separator (9) has a gas-liquid separation zone with a steam outlet, a hot water outlet and an inlet. The inlet is connected to the second heat exchange tube, the hot water outlet is connected to the liquid storage area, and an exhaust pipe is provided at the steam outlet. A steam valve (10) for controlling the steam discharge is provided on the exhaust pipe.

9. The water supplement preheating device of claim 3, wherein the water supplement preheating device is characterized by: The water preheater (4) adopts a double-walled plate heat exchanger.

10. The water supplement preheating device of claim 2, wherein the water supplement preheating device is characterized by: The valves used in the throttling device (12) are all electronic expansion valves or capillary tubes.

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