A heat exchange station system for long-distance heating with large temperature differences

Abstract

A heat exchange station system for long-distance heating with large temperature differences includes an organic Rankine cycle, a vapor compression heat pump, an intermediate heat exchanger, a primary heat network flow path, a secondary heat network flow path, and a power unit. Secondary heat network water from a user is divided from one path into three parallel paths. The organic Rankine cycle utilizes the high-quality heat from the primary heat network water to drive the vapor compression heat pump, and uses waste heat to heat the first path of secondary heat network water. The power unit supplements the driving force of the vapor compression heat pump, while the intermediate heat exchanger utilizes the medium-quality heat from the primary heat network water to heat the second path of secondary heat network water. The vapor compression heat pump utilizes the low-quality heat from the primary heat network water to heat the third path of secondary heat network water. After heat exchange, the three parallel paths of secondary heat network water are combined into one path and returned to the user. This invention improves the waste heat recovery and conversion rate, avoids unstable performance of absorption heat pumps, and simultaneously improves the unevenness of heat exchange temperature differences, thereby increasing heat exchange efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste heat recovery and utilization, and in particular relates to a heat exchange station system for long-distance heating with a large temperature difference. Background Art

[0002] A district heating system consists of factories, heating networks (primary and secondary), heat exchange stations, and users. The primary network connects the factory and the heat exchange station, while the secondary network connects the heat exchange station and users. The factory supplies high-temperature fluid from the primary network to the heat exchange station for heat exchange. The cooled, low-temperature fluid then flows back to the factory. The heat exchange station heats the secondary network fluid from the user. This heating method is typically heat exchanged with a heat exchanger. However, heating is only possible when the return temperature of the primary network is higher than that of the secondary network. However, when the return temperature of the primary network is lower, users can utilize more heat, requiring less flow for long-distance transport, resulting in less heat loss. The factory can also utilize low-grade industrial waste heat, thereby reducing heating energy consumption. The patent application with publication number CN114251709A proposes a heat exchange station solution consisting of an absorption heat pump and a heat exchanger, which can reduce the return temperature of the primary network. However, the absorption heat pump of this method is in a negative pressure environment, which is prone to air leakage and the generation of non-condensable gases, causing the performance of the absorption heat pump to deteriorate. At the same time, since the phase change temperature of the refrigerant in the condenser and evaporator in the absorption heat pump is constant, the heat exchange temperature difference during the heat exchange process is poorly uniform, and the heat exchange efficiency is low. The heat exchange station solution still needs to be optimized. Summary of the Invention

[0003] The purpose of the present invention is to address the problems in the above-mentioned prior art and provide a heat exchange station system for long-distance heating with large temperature differences, which can improve the waste heat recovery conversion rate, avoid the unstable performance of the absorption heat pump, and at the same time improve the unevenness of the heat exchange temperature difference and increase the heat exchange efficiency.

[0004] In order to achieve the above object, the present invention has the following technical solutions:

[0005] A heat exchange station system for long-distance heat supply with large temperature differences, comprising an organic Rankine cycle device, a vapor compression heat pump, an intermediate heat exchanger, a primary heat network flow path, a secondary heat network flow path, and a power device;

[0006] The secondary hot network water from the user is divided into three parallel routes from one route; the organic Rankine cycle device uses the high-grade heat of the primary hot network water supply to drive the steam compression heat pump, and uses the waste heat to heat the first route of secondary hot network water; the power device supplements the driving force of the steam compression heat pump, and the intermediate heat exchanger uses the medium-grade heat of the primary hot network water supply to heat the second route of secondary hot network water; the steam compression heat pump uses the low-grade heat of the primary hot network water supply to heat the third route of secondary hot network water; the three parallel routes of secondary hot network water are combined into one route after heat exchange and returned to the user.

[0007] As a preferred solution, the organic Rankine cycle device includes an expander, a condensing heat exchanger and an evaporating heat exchanger, and the vapor compression heat pump includes a compressor, a condenser and an evaporator;

[0008] The primary heat network water supply passes through the evaporation heat exchanger, the intermediate heat exchanger, and the evaporator in sequence, releasing heat in a descending temperature range, so that the primary heat network return water temperature is lower than the secondary heat network water temperature; the organic Rankine cycle device absorbs the high-grade heat of the primary heat network water supply, and the ORC working fluid inside the organic Rankine cycle device is heated to a superheated gas state, enters the expander to expand and perform work, providing power for the compressor of the vapor compression heat pump. The ORC working fluid in the exhausted state after expansion heats the first secondary heat network water, causing the first secondary heat network water to be heated to the secondary heat network heating temperature; the second secondary heat network water absorbs the medium-grade heat of the primary heat network water supply in the intermediate heat exchanger and is heated to the secondary heat network heating temperature; the vapor compression heat pump uses the low-grade heat of the primary heat network water supply to heat the third secondary heat network water, causing the third secondary heat network water to be heated to the secondary heat network heating temperature; the average heat exchange temperature of the condensing heat exchanger is lower than that of the evaporation heat exchanger, and the average heat exchange temperature of the evaporator is lower than that of the condenser.

[0009] As a preferred solution, the power device is connected between the expander and the compressor, and the power device includes a motor, a first clutch, a second clutch and a transmission; the organic Rankine cycle device also includes an expander output shaft, and the vapor compression heat pump also includes a compressor drive shaft, the expander output shaft is connected to the expander, and the compressor drive shaft is connected to the compressor; the expander output shaft is connected to the compressor drive shaft through the transmission and the first clutch, and the motor is connected to the compressor drive shaft through the second clutch, the first clutch and the second clutch are both connected or disconnected with the compressor drive shaft, and the expander and the motor transmit power to the compressor simultaneously or individually.

[0010] As a preferred solution, when the water supply temperature of the primary heating network is greater than 100°C, the motor does not start, the first clutch is connected to the compressor drive shaft, the second clutch is disconnected, and the compressor is completely driven by the expander;

[0011] When the water supply temperature of the primary heating network is between 70°C and 100°C, the motor starts, the first clutch and the second clutch connect the compressor drive shaft, and the compressor is driven by the expander and the motor together; when the water supply temperature of the primary heating network is lower than 70°C, the motor starts, the first clutch disconnects the compressor drive shaft, the second clutch is connected, the compressor is completely driven by the motor, the first three-way valve bypasses the evaporation heat exchanger, the second three-way valve bypasses the condensation heat exchanger, the organic Rankine cycle device does not work and does not exchange heat with the primary heating network and the secondary heating network.

[0012] As a preferred solution, a first three-way valve is provided in the primary heat network flow path; a second three-way check valve is provided in the secondary heat network flow path; the first three-way valve is located between the factory and the evaporative heat exchanger, and is used to bypass the evaporative heat exchanger, so that the primary heat network water supply does not pass through the organic Rankine cycle device but can only pass through the intermediate heat exchanger and evaporator in sequence; the second three-way valve is used to divide the secondary heat network water from the user from one path into three parallel paths, and after heat exchange with the condensing heat exchanger, the intermediate heat exchanger, and the condenser respectively, the three paths are then combined into one path and returned to the user;

[0013] The second three-way valve is located between the user and the condensing heat exchanger, and is used to bypass the condensing heat exchanger, so that the secondary hot network water does not pass through the organic Rankine cycle device but can only pass through the intermediate heat exchanger and condenser in parallel. When the check valve is bypassed, the secondary hot network water cannot flow to the condensing heat exchanger.

[0014] As a preferred solution, a regenerative heat exchanger is provided inside the organic Rankine cycle device, a pump is provided on the pipeline connected to the condensing heat exchanger, and the regenerative heat exchanger is provided between the pipeline connected to the expander and the evaporating heat exchanger and the pipeline connected to the condensing heat exchanger and the pump; a regenerative heat exchanger is provided inside the vapor compression heat pump, an expansion valve is provided on the pipeline connected to the evaporator, and the regenerative heat exchanger is provided between the pipeline connected to the compressor and the condenser and the pipeline connected to the expansion valve and the evaporator.

[0015] As a preferred solution, the internal circulation heat pump working fluid of the vapor compression heat pump, the ORC working fluid and the heat pump working fluid are both non-azeotropic mixed working fluids.

[0016] As a preferred solution, the bubble point temperature range of the ORC working fluid under standard pressure is 240K~310K, and the dew point temperature range is 250K~320K; the bubble point temperature range of the heat pump working fluid under standard pressure is 210K~290K, and the dew point temperature range is 220K~300K.

[0017] As a preferred solution, the expander and the compressor are both provided with an air supply port; the evaporative heat exchanger is composed of a first evaporative heat exchanger and a second evaporative heat exchanger, the first evaporative heat exchanger and the second evaporative heat exchanger are connected to the condensing heat exchanger via a first pump and a second pump respectively; the water supply of the primary heat network passes through the first evaporative heat exchanger and the second evaporative heat exchanger in sequence, and the ORC working fluid is pumped by the first pump and the second pump respectively. The average temperature and pressure of the ORC working fluid in the first evaporative heat exchanger are higher than those in the second evaporative heat exchanger. The ORC working fluid enters the expander inlet after being output from the first evaporative heat exchanger. After being output from the second evaporation heat exchanger, it enters the air supply port of the expander; the evaporator is composed of a first evaporator and a second evaporator, and the first evaporator and the second evaporator are connected to the condenser through a first expansion valve and a second expansion valve respectively; the primary heat network water supply passes through the first evaporator and the second evaporator in sequence, and the heat pump working fluid passes through the first expansion valve and the second expansion valve respectively before being input. The average temperature and pressure of the heat pump working fluid in the first evaporator are higher than those in the second evaporator. After being output from the first evaporator, the heat pump working fluid enters the air supply port of the compressor, and after being output from the second evaporator, the heat pump working fluid enters the compressor inlet.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The combination of an organic Rankine cycle device and a vapor compression heat pump avoids the performance degradation problem of conventional absorption heat pumps due to the negative pressure environment inside. Furthermore, due to the constant phase change temperature of the refrigerant in the condenser and evaporator of the absorption heat pump, the heat exchange temperature difference during the heat exchange process is poorly uniform, resulting in low heat exchange efficiency. The organic Rankine cycle device in the system of the present invention utilizes the high-grade heat from the primary heating network water supply to drive the vapor compression heat pump, and uses waste heat to heat the first portion of the secondary heating network water. The power unit supplements the driving force of the compressor in the heat pump, and the intermediate heat exchanger utilizes the medium-grade heat from the primary heating network water supply to heat the second portion of the secondary heating network water. The vapor compression heat pump utilizes the low-grade heat from the primary heating network heating fluid to heat the third portion of the secondary heating network water. This effectively improves the waste heat recovery conversion rate, avoids the unstable performance problem of absorption heat pumps, and is more suitable for long-distance heating with large temperature differences.

[0020] Furthermore, the ORC working fluid within the organic Rankine cycle device and the heat pump working fluid within the vapor compression heat pump of the present invention are both non-azeotropic mixtures, which can reduce the unevenness of the heat exchange temperature differences between the evaporation heat exchanger and evaporator, the condensation heat exchanger and condenser, and the primary and secondary heat network water. All heat exchangers within the heat exchange station system of the present invention are arranged in a countercurrent flow configuration, which reduces the unevenness of the heat exchange temperature differences and increases heat exchange efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 A schematic diagram of the structure of a heat exchange station system for long-distance heating with large temperature differences according to a first embodiment of the present invention;

[0023] Figure 2 A temperature-heat exchange diagram for internal heat exchange in a heat exchange station system for long-distance heat supply with large temperature differences according to the first embodiment of the present invention;

[0024] Figure 3 A schematic diagram of the structure of a heat exchange station system for long-distance heating with large temperature differences according to a second embodiment of the present invention;

[0025] Figure 4 A temperature-heat exchange rate diagram for internal heat exchange in a heat exchange station system for long-distance heat supply with large temperature differences according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, ordinary technicians in this field can also derive other embodiments without making any creative work.

[0027] Figure 1 、 Figure 2 Describes an embodiment of the present invention, such as Figure 1 As shown, the heat exchange station system for large temperature difference and long-distance heat supply according to the present invention includes an organic Rankine cycle device, a vapor compression heat pump, an intermediate heat exchanger 300, a primary heat network flow path, a secondary heat network flow path, and a power unit. The organic Rankine cycle device includes an expander 101, a condensing heat exchanger 102, a pump 103, an evaporating heat exchanger 104, a regenerative heat exchanger 105, an ORC working fluid, and an expander output shaft 107; the vapor compression heat pump includes a compressor 201, a condenser 202, an expansion valve 203, an evaporator 204, a regenerator 205, a heat pump working fluid, and a compressor drive shaft 207; a first three-way valve 401 is provided in the primary heat network flow path; a second three-way valve 501 and a check valve 511 are provided in the secondary heat network flow path; and the power unit includes a motor 601, a first clutch 611, a second clutch 612, and a transmission 621.

[0028] In the primary heat network flow path, the primary heat network supply water from the factory passes through the evaporative heat exchanger 104, the intermediate heat exchanger 300, and the evaporator 204 in sequence, and releases heat in sequence in the temperature range from high to low, so that the return water temperature of the primary heat network can be lower than the water temperature of the secondary heat network; in the secondary heat network flow path, the secondary heat network water from the user is divided from one path into three parallel paths, and after heat exchange with the condensing heat exchanger 102, the intermediate heat exchanger 300, and the condenser 202, the three paths are combined into one path and returned to the user.

[0029] In the organic Rankine cycle device, the ORC working medium absorbs heat from the evaporating heat exchanger 104, and its temperature rises to a superheated gas state. It then enters the expander 101 to expand and perform work. The expander 101 transmits power to the compressor 201 through the expander output shaft 107, the transmission 621, the first clutch 611, and the compressor drive shaft 207. The exhaust steam ORC working medium that has performed work flows through the regenerative heat exchanger 105 to exchange heat with the liquid ORC working medium. The exhaust steam ORC working medium releases heat and cools down, while the liquid ORC working medium absorbs heat and heats up. The cooled exhaust steam ORC working medium flows through the condensing heat exchanger 102 to exchange heat with the first part of the secondary heat network water. The exhaust steam ORC working medium condenses into liquid ORC working medium. The liquid ORC working medium is driven and pressurized by the pump 103, flows through the regenerative heat exchanger 105, absorbs heat and heats up, and then enters the evaporating heat exchanger 104. This process is repeated.

[0030] In a vapor compression heat pump, the heat pump working fluid absorbs heat from the evaporator 204, and its temperature rises and its phase changes into a gaseous state or a gas-liquid two-phase heat pump working fluid; it then flows through the regenerator 205 to exchange heat with the liquid heat pump working fluid, and the gaseous state or the gas-liquid two-phase heat pump working fluid absorbs heat and its temperature rises to become a superheated gaseous heat pump working fluid, and the liquid heat pump working fluid releases heat and its temperature drops to become a subcooled liquid heat pump working fluid; the superheated gaseous heat pump working fluid enters the compressor 201, where it is pressurized and heated to become a high-temperature and high-pressure heat pump working fluid; the high-temperature and high-pressure heat pump working fluid flows through the condenser 202 to exchange heat with the second part of the secondary heat network water, and the high-temperature and high-pressure heat pump working fluid releases heat and condenses into a liquid heat pump working fluid; the liquid heat pump working fluid flows through the regenerator 205 and is supercooled before entering the evaporator 204, and this process is repeated.

[0031] When the water supply temperature of the primary heating network is greater than 100°C, the motor 601 does not start, the first clutch 611 is connected to the compressor drive shaft 207, the second clutch 612 is disconnected, and the compressor 201 is completely driven by the expander 101; when the water supply temperature of the primary heating network is between 70°C and 100°C, the motor 601 is started, the first clutch 611 and the second clutch 612 are connected to the compressor drive shaft 207, and the compressor 201 is driven jointly by the expander 101 and the motor 601; when the water supply temperature of the primary heating network is lower than 70°C, the motor 601 is started, the first clutch 611 is disconnected from the compressor drive shaft 207, and the second clutch 612 is connected, and the compressor 201 is completely driven by the motor 601, the first three-way valve 401 bypasses the evaporating heat exchanger 104, the second three-way valve 501 bypasses the condensing heat exchanger 102, the organic Rankine cycle device 100 does not operate and does not exchange heat with the primary heating network or the secondary heating network.

[0032] like Figure 2 As shown, the temperature-heat exchange rate diagram illustrates the heat exchange situation inside the heat exchange station system. It can be seen that after adopting the flow arrangement of non-azeotropic mixed working fluid and countercurrent heat exchange, the heat exchange curve forms a plurality of approximate "parallelograms", while the heat exchange curve of the heat exchange station system based on absorption heat pump is a "triangle" in the phase change heat exchange curve in the evaporator and condenser. The phase change temperature on the working fluid side remains unchanged, and the heat exchange temperature difference is uneven. The heat exchange temperature difference uniformity of the heat exchange station system using the present invention is better than that of the heat exchange station system based on absorption heat pump; the average heat exchange temperature of the condensing heat exchanger 102 is lower than that of the evaporating heat exchanger 104, and the average heat exchange temperature of the evaporator 204 is lower than that of the condenser 202.

[0033] The temperature change of the primary heat network's supply water through the heat exchanger is significantly greater than that of the secondary heat network. Furthermore, since zeotropic mixtures exhibit a more pronounced phase transition temperature glide at low pressure, they cannot simultaneously match the heat exchange temperature difference between the two sides. If a refrigerant with a larger temperature glide is selected, the excessively high condensing temperature glide will affect the operating efficiency of the ORC and heat pump systems. Therefore, the heat exchangers on the primary heat network side, where the temperature change is greater, are zoned to match the heat exchange temperature difference, as described in Example 2.

[0034] Figure 3 、 Figure 4 Another embodiment 2 of the present invention is described, as Figure 3As shown, the heat exchange station system for large temperature difference and long distance heat supply in this embodiment includes an organic Rankine cycle device, a vapor compression heat pump, an intermediate heat exchanger 300, a primary heat network flow path, a secondary heat network flow path, and a power device. The organic Rankine cycle device includes an expander 101, a condensing heat exchanger 102, a first pump 103-1, a second pump 103-2, a first evaporating heat exchanger 104-1, a second evaporating heat exchanger 104-2, a regenerative heat exchanger 105, an ORC working medium, and an expander output shaft 107; the vapor compression heat pump includes a compressor 201, a condenser 202 , a first expansion valve 203-1, a second expansion valve 203-2, a first evaporator 204-1, a second evaporator 204-2, a regenerator 205, a heat pump working fluid, and a compressor drive shaft 207; a first three-way valve 401 is provided in the primary heat network flow path; a second three-way valve 501 and a check valve 511 are provided in the secondary heat network flow path; the power unit includes a motor 601, a first clutch 611, a second clutch 612, and a transmission 621; in this embodiment, the expander 101 of the organic Rankine cycle device and the compressor 201 of the vapor compression heat pump are provided with an air supply port.

[0035] The water supply of the primary heat network passes through the first evaporation heat exchanger 104-1 and the second evaporation heat exchanger 104-2 in sequence. The ORC working fluid therein is pumped by the first pump 103-1 and the second pump 103-2 respectively. The average temperature and pressure of the ORC working fluid in the first evaporation heat exchanger 104-1 are higher than those in the second evaporation heat exchanger 104-2. The ORC working fluid enters the inlet of the expander 101 after exiting the first evaporation heat exchanger 104-1, and enters the gas supply port in the middle of the expander 101 after exiting the second evaporation heat exchanger 104-2. The evaporator 204 is divided into two parts. The primary heat network water supply passes through the first evaporator 204-1 and the second evaporator 204-2 in sequence. The heat pump working fluid therein passes through the first expansion valve 203-1 and the second expansion valve 203-2 before entering. The average temperature and pressure of the heat pump working fluid in the first evaporator 204-1 are higher than those in the second evaporator 204-2. After exiting the first evaporator 204-1, the heat pump working fluid enters the middle air supply port of the compressor 201. After exiting the second evaporator 204-2, it enters the inlet of the compressor 201. Except for the absence of a reheater, the rest of the process is the same as Example 1.

[0036] like Figure 4 As shown, due to the partitioning of the heat exchanger, the working fluid flow rate in each evaporating heat exchanger 104 and evaporator 204 is smaller than the flow rate in the corresponding condensing heat exchanger 102 and condenser 202. Therefore, the slope of the evaporating side in the temperature-heat exchange diagram is greater than the slope of the condensing side. Compared with Example 1, the heat exchange temperature difference can achieve higher uniformity, thereby improving the heat exchange efficiency.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to impose any limitation on the technical solution of the present invention. Those skilled in the art should understand that, without departing from the spirit and principles of the present invention, the technical solution can also be subjected to several simple modifications and replacements, and these modifications and replacements will also fall within the scope of protection covered by the claims.

Claims

1. A heat exchange station system for long-distance heating with large temperature differences, characterized in that: It comprises an organic Rankine cycle device, a vapor compression heat pump, an intermediate heat exchanger (300), a primary heat network flow path, a secondary heat network flow path and a power device; Secondary hot water from the user is divided into three parallel routes from one route; the organic Rankine cycle device uses the high-grade heat of the primary hot water supply to drive the steam compression heat pump to operate, and uses the waste heat to heat the first route of secondary hot water; the power device supplements the driving force of the steam compression heat pump, and the intermediate heat exchanger (300) uses the medium-grade heat of the primary hot water supply to heat the second route of secondary hot water; the steam compression heat pump uses the low-grade heat of the primary hot water supply to heat the third route of secondary hot water; the three parallel routes of secondary hot water are combined into one route after heat exchange and returned to the user; The organic Rankine cycle device comprises an expander (101), a condensing heat exchanger (102), and an evaporating heat exchanger (104); the vapor compression heat pump comprises a compressor (201), a condenser (202), and an evaporator (204); The primary heat network water supply passes through the evaporation heat exchanger (104), the intermediate heat exchanger (300) and the evaporator (204) in sequence, and releases heat in the temperature range from high to low, so that the return water temperature of the primary heat network is lower than the water temperature of the secondary heat network; the organic Rankine cycle device (100) absorbs the high-quality heat of the primary heat network water supply, and the ORC working fluid inside the organic Rankine cycle device (100) is heated to a superheated gas state and enters the expander (101) to expand and perform work, thereby providing power for the compressor (201) of the vapor compression heat pump. The ORC working fluid in the exhausted state after expansion is heated to a superheated gas state. The first secondary heat network water is heated to the secondary heat network heating temperature; the second secondary heat network water absorbs the medium-grade heat of the primary heat network water in the intermediate heat exchanger (300) and is heated to the secondary heat network heating temperature; the steam compression heat pump utilizes the low-grade heat of the primary heat network water to heat the third secondary heat network water, and heats the third secondary heat network water to the secondary heat network heating temperature; the average heat exchange temperature of the condensing heat exchanger (102) is lower than that of the evaporating heat exchanger (104), and the average heat exchange temperature of the evaporator (204) is lower than that of the condenser (202); The power device is connected between the expander (101) and the compressor (201), and includes a motor (601), a first clutch (611), a second clutch (612), and a transmission (621); the organic Rankine cycle device also includes an expander output shaft (107), and the vapor compression heat pump (200) also includes a compressor drive shaft (207). The expander output shaft (107) is connected to the expander (101), and the compressor drive shaft (207) is connected to the compressor (201); the expander output shaft (107) is connected to the compressor drive shaft (207) through the transmission (621) and the first clutch (611), and the motor (601) is connected to the compressor drive shaft (207) through the second clutch (612). The first clutch (611) and the second clutch (612) are both connected to or disconnected from the compressor drive shaft (207). The expander (101) and the motor (601) transmit power to the compressor (201) simultaneously or individually.

2. The heat exchange station system for large temperature difference and long distance heating according to claim 1 is characterized in that: When the water supply temperature of the primary heating network is greater than 100° C., the motor (601) is not started, the first clutch (611) is connected to the compressor drive shaft (207), the second clutch (612) is disconnected, and the compressor (201) is completely driven by the expander (101); When the water supply temperature of the primary heating network is between 70°C and 100°C, the motor (601) is started, the first clutch (611) and the second clutch (612) are connected to the compressor drive shaft (207), and the compressor (201) is driven jointly by the expander (101) and the motor (601); when the water supply temperature of the primary heating network is lower than 70°C, the motor (601) is started, the first clutch (611) is disconnected from the compressor drive shaft (207), the second clutch (612) is connected, the compressor (201) is completely driven by the motor (601), the first three-way valve (401) bypasses the evaporation heat exchanger (104), the second three-way valve (501) bypasses the condensation heat exchanger (102), and the organic Rankine cycle device does not work and does not exchange heat with the primary heating network and the secondary heating network.

3. The heat exchange station system for large temperature difference and long distance heating according to claim 1 is characterized in that: A first three-way valve (401) is provided in the primary heat network flow path; a second three-way valve (501) and a check valve (511) are provided in the secondary heat network flow path; the first three-way valve (401) is located between the factory and the evaporative heat exchanger (104), and is used to bypass the evaporative heat exchanger (104), so that the primary heat network water supply does not pass through the organic Rankine cycle device but can only pass through the intermediate heat exchanger (300) and the evaporator (204) in sequence; the secondary heat network water from the user is divided from one path into three parallel paths through the second three-way valve (501), and after heat exchange with the condensing heat exchanger (102), the intermediate heat exchanger (300), and the condenser (202) respectively, the three paths are then combined into one path and returned to the user; The second three-way valve (501) is located between the user and the condensing heat exchanger (102) and is used to bypass the condensing heat exchanger (102), so that the secondary hot network water does not pass through the organic Rankine cycle device but can only pass through the intermediate heat exchanger (300) and the condenser (202) in parallel. When the check valve (511) realizes the bypass, the secondary hot network water cannot flow to the condensing heat exchanger (102).

4. The heat exchange station system for large temperature difference and long distance heating according to claim 1 is characterized in that: A regenerative heat exchanger (105) is provided inside the organic Rankine cycle device (100), a pump (103) is provided on the pipeline connected to the condensing heat exchanger (102), and the regenerative heat exchanger (105) is provided between the pipeline connected to the expander (101) and the evaporating heat exchanger (104) and the pipeline connected to the condensing heat exchanger (102) and the pump (103); a regenerative heat exchanger (205) is provided inside the vapor compression heat pump, an expansion valve (203) is provided on the pipeline connected to the evaporator (204), and the regenerative heat exchanger (205) is provided between the pipeline connected to the compressor (201) and the condenser (202) and the pipeline connected to the expansion valve (203) and the evaporator (204).

5. The heat exchange station system for long-distance heating with large temperature differences according to claim 1 is characterized in that: The internal circulation heat pump working fluid of the vapor compression heat pump, the ORC working fluid and the heat pump working fluid are both non-azeotropic mixed working fluids.

6. The heat exchange station system for large temperature difference and long distance heating according to claim 5, characterized in that: The bubble point temperature range of the ORC working fluid under standard pressure is 240K~310K, and the dew point temperature range is 250K~320K; the bubble point temperature range of the heat pump working fluid under standard pressure is 210K~290K, and the dew point temperature range is 220K~300K.

7. The heat exchange station system for large temperature difference and long distance heating according to claim 1 is characterized in that: The expander (101) and the compressor (201) are both provided with an air supply port; the evaporation heat exchanger (104) is composed of a first evaporation heat exchanger (104-1) and a second evaporation heat exchanger (104-2); the first evaporation heat exchanger (104-1) and the second evaporation heat exchanger (104-2) are connected to the condensation heat exchanger (102) via a first pump (103-1) and a second pump (103-2) respectively; the primary heat network water supply is sequentially supplied through the first The ORC working medium is pumped by the first pump (103-1) and the second pump (103-2) respectively. The average temperature and pressure of the ORC working medium in the first evaporation heat exchanger (104-1) are higher than those in the second evaporation heat exchanger (104-2). The ORC working medium is output from the first evaporation heat exchanger (104-1) and enters the inlet of the expander (101). The ORC working medium is output from the second evaporation heat exchanger (104-2). -2) output and then enter the air supply port of the expander (101); the evaporator (204) is composed of a first evaporator (204-1) and a second evaporator (204-2), the first evaporator (204-1) and the second evaporator (204-2) are connected to the condenser (202) through a first expansion valve (203-1) and a second expansion valve (203-2) respectively; the primary heat network water supply passes through the first evaporator (204-1), the second evaporator (204-2) in sequence The heat pump working fluid passes through the first expansion valve (203-1) and the second expansion valve (203-2) before being input. The average temperature and pressure of the heat pump working fluid in the first evaporator (204-1) are higher than those in the second evaporator (204-2). The heat pump working fluid enters the air supply port of the compressor (201) after being output from the first evaporator (204-1). The heat pump working fluid enters the inlet of the compressor (201) after being output from the second evaporator (204-2).

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