A zero-temperature drop heating system for a pressure isolation station based on a high back pressure unit and a working method thereof

Abstract

The present invention discloses a zero-temperature drop heating system for a pressure isolation station based on a high back-pressure unit and a working method thereof, which belongs to the technical field of cogeneration. It includes a high back-pressure condenser, a first station zero-subnet circulation pump, a first station steam heater, a pressure reducing turbine unit, a thermal power station, a pressure isolation station primary network circulation pump, a return water booster pump and a pressure isolation station plate heat exchanger. The pressure isolation station and the booster pump (station) serve as backup for each other and can be switched according to the load on the thermal network side and the return water temperature of the thermal power station primary network, with flexible operation mode; when the heat load on the thermal network side or the return water temperature of the primary network thermal network is high, the inlet water temperature entering the high back-pressure condenser can be effectively reduced to ensure the safe operation of the unit, while increasing the proportion of heat exchanged by the condenser, so that the overall heating economy is optimized and the overall operating costs are significantly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of cogeneration, and in particular relates to a zero-temperature drop heating system for a pressure isolation station based on a high back pressure unit and a working method thereof. Background Art

[0002] When high back pressure units are used for heating, the heat released by the condensation of steam in the condenser is absorbed by the circulating water of the heating network, which greatly reduces the loss of cold sources and greatly improves the economic efficiency of the unit. However, high back pressure heating has the problem of low water supply temperature. Its upper limit of water supply is about 80℃, which does not meet the water supply requirements of the heating network in the severe cold period in northern regions. Therefore, a steam secondary heating system is usually configured. The circulating water of the heating network first passes through the condenser for the first heating, absorbs the waste heat of the low-pressure cylinder exhaust steam, and then passes through the steam heater of the first heating station to complete the second heating to generate high-temperature hot water.

[0003] The temperature of circulating water entering the condenser should be strictly controlled and should not exceed a certain limit. On the one hand, high water temperature will affect the safe operation of the unit, and on the other hand, it will reduce the proportion of the first heat exchange, thereby reducing the overall heating economy. In addition, the pressure isolation station set up on the heat network side increases the power consumption and heat loss of the primary network circulation pump. At the same time, due to the addition of a first-level heat exchange, the water temperature of the heat network circulating water entering the high back pressure condenser is indirectly increased. Summary of the invention

[0004] In order to solve the above-mentioned existing problems, the purpose of the present invention is to provide a zero-temperature reduction heating system for a pressure isolation station based on a high back pressure unit and a working method thereof, which has a flexible operation mode and can effectively reduce the inlet water temperature entering the high back pressure condenser to ensure the safe operation of the unit, while increasing the proportion of heat exchange in the condenser, thereby optimizing the overall heating economy and significantly reducing the overall operating costs.

[0005] The present invention is achieved through the following technical solutions:

[0006] The invention discloses a zero-temperature drop heating system for a pressure isolation station based on a high back pressure unit, comprising a high back pressure condenser, a first station zero-subnet circulation pump, a first station steam heater, a vacuum turbine unit, a thermal power station, a pressure isolation station primary network circulation pump, a return water booster pump and a pressure isolation station plate heat exchanger;

[0007] The high temperature side outlet of the plate heat exchanger of the pressure isolation station is connected to the water side inlet of the high back pressure condenser, and the water side outlet of the high back pressure condenser is connected to the inlet of the zero-order network circulating pump of the first station; the outlet of the zero-order network circulating pump of the first station is connected to the water side inlet of the steam heater of the first station; the water side outlet of the steam heater of the first station is respectively connected to the high temperature side inlets of the pressure reducing turbine unit and the plate heat exchanger of the pressure isolation station; the outlet of the pressure reducing turbine unit is connected to the high temperature side inlet of the thermal power station; the low temperature side outlet of the plate heat exchanger of the pressure isolation station is connected to the high temperature side inlet of the thermal power station; the high temperature side outlet of the thermal power station is respectively connected to the inlet of the primary network circulating pump of the pressure isolation station and the inlet of the return water booster pump; the outlet of the primary network circulating pump of the pressure isolation station is connected to the low temperature side inlet of the plate heat exchanger of the pressure isolation station; the outlet of the return water booster pump is connected to the water side inlet of the high back pressure condenser.

[0008] Preferably, the inlet of the first station zero-time network circulation pump is connected to a water replenishment constant pressure buffer water tank.

[0009] Preferably, a #3 gate valve is provided between the high-temperature side outlet of the plate heat exchanger of the pressure isolation station and the water side inlet of the high back-pressure condenser, a #1 gate valve is provided between the water side outlet of the steam heater of the first station and the pressure reducing turbine unit, a #2 gate valve is provided between the water side outlet of the steam heater of the first station and the high-temperature side inlet of the plate heat exchanger of the pressure isolation station, a #5 gate valve is provided between the outlet of the pressure reducing turbine unit and the high-temperature side inlet of the thermal power station, a #6 gate valve is provided between the low-temperature side outlet of the plate heat exchanger of the pressure isolation station and the high-temperature side inlet of the thermal power station, a #7 gate valve is provided between the high-temperature side outlet of the thermal power station and the inlet of the primary network circulation pump of the pressure isolation station, a #8 gate valve is provided between the high-temperature side outlet of the thermal power station and the inlet of the return water booster pump, and a #4 gate valve is provided between the outlet of the return water booster pump and the water side inlet of the high back-pressure condenser.

[0010] Preferably, a #1 regulating valve is connected between the water side inlet and the water side outlet of the high back pressure condenser, a #2 regulating valve is connected between the water side inlet and the water side outlet of the first station steam heater, a #3 regulating valve is connected between the high temperature side inlet and the high temperature side outlet of the pressure isolation station plate heat exchanger, and a #4 regulating valve is connected between the low temperature side inlet and the low temperature side outlet of the pressure isolation station plate heat exchanger.

[0011] Preferably, a dirt remover is provided between the high temperature side outlet of the thermal power station and the inlet of the return water booster pump.

[0012] Preferably, two bypasses are provided between the inlet and the outlet of the return water booster pump, one bypass is provided with a water hammer prevention check valve, and the other bypass is provided with a static pressure control pump.

[0013] The working method of the zero-temperature drop heating system of the pressure isolation station based on the high back pressure unit disclosed in the present invention includes:

[0014] Normal working conditions:

[0015] When the heat load or the return water temperature of the primary network heat network is lower than the preset value, the vacuum turbine unit and the return water booster pump will not be put into operation, and the plate heat exchanger of the pressure isolation station will separate the system into the zero-time network and the primary network; on the zero-time network side, the circulating water of the heat network first enters the high back pressure condenser for heating, and then enters the steam heater of the first station for further heating and temperature increase, and the circulation power is provided by the zero-time circulation pump of the first station; on the primary network side, the outlet water of the low temperature side of the plate heat exchanger of the pressure isolation station goes to the thermal power station through the water supply pipeline, and after releasing the heat, it returns to the low temperature side inlet of the plate heat exchanger of the pressure isolation station from the return water pipeline for the next heat exchange cycle, and the circulation power is provided by the primary network circulation pump of the pressure isolation station; the temperature of the circulating water of the heat network entering the high back pressure condenser is higher than the return water temperature of the thermal power station;

[0016] Zero temperature drop condition of pressure isolation station:

[0017] When the heat load or the return water temperature of the primary network is higher than the preset value, the plate heat exchanger of the pressure isolation station will not be put into operation; the zero-secondary network and the primary network are directly connected, and the return water of the thermal power station enters the high back pressure condenser for heating through the return water booster pump, and then enters the steam heater of the first station for further heating and temperature increase, and then enters the thermal power station for heat exchange after being reduced pressure by the pressure reducing turbine unit; the circulating water temperature of the thermal network entering the high back pressure condenser is equal to the return water temperature of the thermal power station.

[0018] Preferably, under normal operating conditions, the first station zero-time circulation pump and the pressure isolation station primary network circulation pump both adopt the inlet constant pressure operation mode; under the zero temperature drop condition of the pressure isolation station, the first station zero-time circulation pump and the return water booster pump are operated in series, and the first station zero-time circulation pump adopts the outlet constant pressure operation mode, and the return water booster pump adopts the flow feedback control operation mode.

[0019] Preferably, under the zero temperature drop condition of the pressure isolation station, the pressure reducing turbine unit reduces the zero-time network water supply pressure to the primary network water supply pressure, and the return water booster pump increases the primary network return water pressure to the zero-time network return water pressure.

[0020] Preferably, under the zero temperature drop condition of the pressure isolation station, the potential energy generated by the pressure reduction of the pressure reducing turbine unit drives the return water booster pump, and the insufficient power is then supplied by the motor.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] The present invention discloses a zero-temperature drop heating system for a pressure isolation station based on a high back-pressure unit. The pressure isolation station and the booster pump (station) serve as backup for each other and can be switched according to the load on the heating network side and the return water temperature of the primary network of the thermal power station, with flexible operation mode. When the heat load on the heating network side or the return water temperature of the primary network heating network is high, the inlet temperature of the water entering the high back-pressure condenser can be effectively reduced to ensure the safe operation of the unit, while increasing the proportion of heat exchanged by the condenser, thereby optimizing the overall heating economy and significantly reducing the overall operating costs.

[0023] Furthermore, the inlet of the first station zero-time network circulation pump is connected to a water replenishment constant pressure buffer tank, which can replenish water and maintain constant pressure for the system and absorb the water hammer generated by the return water booster pump.

[0024] Furthermore, the regulating valves connected at various locations regulate the flow of circulating water participating in the heat exchange at this stage.

[0025] Furthermore, a decontaminator is provided between the high-temperature side outlet of the thermal power station and the inlet of the return water booster pump, which can improve water quality, increase the service life of equipment in the system, reduce maintenance, and ensure the safety and stability of system operation.

[0026] Furthermore, a water hammer check valve is connected beside the return water booster pump to absorb the water hammer generated by the zero-time network circulation pump at the first station; a static pressure control pump is connected beside the return water booster pump to pump the water leaking from the zero-time network to the primary network back to the zero-time network pipeline when the pressure of the return water booster pump inlet network exceeds the limit.

[0027] The working method of the zero-temperature drop heating system of the pressure isolation station based on the high back-pressure unit disclosed in the present invention has a flexible operation mode and a high degree of automation. It can effectively reduce the inlet water temperature entering the high back-pressure condenser to ensure the safe operation of the unit, while increasing the proportion of heat exchange in the condenser, thereby optimizing the overall heating economy and significantly reducing the overall operating costs.

[0028] Furthermore, under the zero temperature drop condition of the pressure isolation station, there is no heat loss caused by the heat exchange of the plate heat exchanger of the pressure isolation station and the power consumption of the primary network circulation pump of the pressure isolation station. The power of the return water booster pump is mainly provided by the potential energy generated by the pressure reducing turbine unit. The increased power consumption is limited, and the overall operating cost is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0030] Figure 2 It is a system equivalent structure diagram of the system of the present invention under normal working conditions;

[0031] Figure 3 It is a system equivalent structure diagram of the system of the present invention under zero temperature drop conditions.

[0032] In the figure: 1-high back pressure condenser; 2-#1 regulating valve; 3-make-up water constant pressure buffer water tank; 4-first station zero network circulation pump; 5-first station steam heater; 6-#2 regulating valve; 7-#1 gate valve; 8-#2 gate valve; 9-#3 regulating valve; 10-#3 gate valve; 11-#4 gate valve; 12-pressure reducing turbine unit; 13-#5 gate valve; 14-#6 gate valve; 15-#4 regulating valve; 16-thermal power station; 17-#7 gate valve; 18-pressure isolation station primary network circulation pump; 19-#8 gate valve; 20-decontamination device; 21-anti-water hammer check valve; 22-return water booster pump; 23-static pressure control pump; 24-pressure isolation station plate heat exchanger. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, the contents of which are intended to explain the present invention rather than to limit it:

[0034] like Figure 1 The present invention provides a zero-temperature drop heating system for a pressure isolation station based on a high back pressure unit, comprising a high back pressure condenser 1, a make-up water constant pressure buffer water tank 3, a first station zero-time network circulation pump 4, a first station steam heater 5, a pressure reducing turbine unit 12, a thermal power station 16 and a pressure isolation station plate heat exchanger 24.

[0035] The high temperature side outlet of the plate heat exchanger 24 of the pressure isolation station is connected to the water side inlet of the high back pressure condenser 1 through the #3 gate valve 10, and the water side outlet of the high back pressure condenser 1 is connected to the inlet of the zero-order network circulating pump 4 of the first station, and a #1 regulating valve 2 is connected between the water side inlet and the water side outlet of the high back pressure condenser 1; the water replenishment constant pressure buffer water tank 3 is connected to the inlet of the zero-order network circulating pump 4 of the first station, and the outlet of the zero-order network circulating pump 4 of the first station is connected to the water side inlet of the steam heater 5 of the first station; the water side outlet of the steam heater 5 of the first station is connected to the pressure reducing turbine unit 12 through the #1 gate valve 7, and is connected to the high temperature side inlet of the plate heat exchanger 24 of the pressure isolation station through the #2 gate valve 8; a #2 regulating valve 6 is connected between the water side inlet and the water side outlet of the steam heater 5 of the first station; a #3 regulating valve 9 is connected between the high temperature side inlet and the high temperature side outlet of the plate heat exchanger 24 of the pressure isolation station; the outlet of the pressure reducing turbine unit 12 is connected through the The #5 gate valve 13 is connected to the high temperature side inlet of the thermal power station 16; the low temperature side outlet of the pressure isolation station plate heat exchanger 24 is connected to the high temperature side inlet of the thermal power station 16 through the #6 gate valve 14; the high temperature side outlet of the thermal power station 16 is connected to the inlet of the primary network circulation pump 18 of the pressure isolation station through the #7 gate valve 17, and is connected to the inlet of the decontaminant 20 through the #8 gate valve 19; the outlet of the primary network circulation pump 18 of the pressure isolation station is connected to the low temperature side inlet of the plate heat exchanger 24 of the pressure isolation station; a #4 regulating valve 15 is connected between the low temperature side inlet and the low temperature side outlet of the plate heat exchanger 24 of the pressure isolation station; the outlet of the decontaminant 20 is connected to the inlet of the return water booster pump 22 and the static pressure control pump 23 respectively, and the outlets of the return water booster pump 22 and the static pressure control pump 23 are connected to the water side inlet of the high back pressure condenser 1 through the #4 gate valve 11; a water hammer prevention check valve 21 is connected between the inlet and outlet of the return water booster pump 22.

[0036] A bypass pipe is set between the high-temperature side inlet and outlet of the pressure isolation station plate heat exchanger 24 and is equipped with a #3 regulating valve 9. A bypass pipe is set between the low-temperature side inlet and outlet of the pressure isolation station plate heat exchanger 24 and is equipped with a #4 regulating valve 15. A bypass pipe is set between the water side inlet and outlet of the first station steam heater 5 and is equipped with a #2 regulating valve 6. A bypass pipe is set between the water side inlet and outlet of the high back pressure condenser 1 and is equipped with a #1 regulating valve 2, so as to adjust the flow rate of circulating water participating in the heat exchange of this stage.

[0037] The working method of the zero temperature drop heating system of the pressure isolation station based on the high back pressure unit includes:

[0038] Normal working conditions:

[0039] When the heat load or the return water temperature of the primary network is low, the plate heat exchanger 24 of the pressure isolation station is put into operation, and the pressure reducing turbine unit 12, the return water booster pump 22 and the static pressure control pump 23 are not put into operation; specifically: close the #1 gate valve 7, #4 gate valve 11, #5 gate valve 13 and #8 gate valve 19, open the #2 gate valve 8, #3 gate valve 10, #6 gate valve 14 and #7 gate valve 17, and the plate heat exchanger 24 of the pressure isolation station separates the system into the zero-secondary network and the primary network. The equivalent diagram of the system under this condition is as follows Figure 2 shown.

[0040] On the zero-second network side, the high-temperature side outlet of the heat network circulating water pressure-isolating station plate heat exchanger 24 enters the high back-pressure condenser 1 through the #3 gate valve 10 for heating, and then enters the first station steam heater 5 for further heating and temperature increase, and enters the pressure-isolating station plate heat exchanger 24 through the #2 gate valve 8 to release heat for the next heat exchange cycle; the circulation power on the zero-second network side is provided by the first station zero-second circulation pump 4, and the first station zero-second circulation pump 4 adopts a constant pressure operation mode, and the constant pressure point is the inlet of the first station zero-second circulation pump 4.

[0041] On the primary network side, the outlet water on the low-temperature side of the plate heat exchanger 24 of the pressure isolation station goes to the thermal power station 16 along the water supply pipeline through the #6 gate valve 14, and after releasing the heat, it returns to the low-temperature side inlet of the plate heat exchanger 24 of the pressure isolation station through the #7 gate valve 17 along the return pipeline for the next heat exchange cycle; the circulation power on the primary network side is provided by the primary network circulation pump 18 of the pressure isolation station. The primary network circulation pump 18 of the pressure isolation station adopts a constant pressure operation mode, and the constant pressure point is the inlet of the primary network circulation pump 18 of the pressure isolation station.

[0042] Bypass pipes are set at the inlet and outlet of the high-temperature side of the pressure isolation station plate heat exchanger 24 and equipped with #3 regulating valve 9 to adjust the circulating water flow rate participating in heat exchange on the high-temperature side of the pressure isolation station plate heat exchanger 24; bypass pipes are set at the inlet and outlet of the low-temperature side of the pressure isolation station plate heat exchanger 24 and equipped with #4 regulating valve 15 to adjust the circulating water flow rate participating in heat exchange on the low-temperature side of the pressure isolation station plate heat exchanger 24; bypass pipes are set at the inlet and outlet of the water side of the first station steam heater 5 and equipped with #2 regulating valve 6 to adjust the circulating water flow rate entering the first station steam heater 5 to participate in heat exchange; bypass pipes are set at the inlet and outlet of the water side of the high back pressure condenser 1 and equipped with #1 regulating valve 2 to adjust the circulating water flow rate entering the high back pressure condenser 1 to participate in heat exchange.

[0043] Under this condition, the plate heat exchanger 24 of the pressure isolation station divides the system into the zero-time network and the primary network. The circulating water temperature of the hot network entering the high back pressure condenser 1 is T B Greater than the return water temperature T of thermal power station 16 C .

[0044] Zero temperature drop condition of pressure isolation station:

[0045] When the heat load or the return water temperature of the primary network is high, the plate heat exchanger 24 of the pressure isolation station is shut down, and the pressure reducing turbine unit 12, the return water booster pump 22 and the static pressure control pump 23 are put into operation. Specifically, the #2 gate valve 8, #3 gate valve 10, #6 gate valve 14 and #7 gate valve 17 are closed, and the #1 gate valve 7, #4 gate valve 11, #5 gate valve 13 and #8 gate valve 19 are opened. The equivalent diagram of the system under this condition is as follows: Figure 3 shown.

[0046] Under this operating condition, the original zero-time network and the primary network are connected, and the return water from the original thermal power station 16 first enters the decontaminant 20 for decontamination to improve the water quality, and then enters the high back pressure condenser 1 for heating through the return water booster pump 22 and the #4 gate valve 11, and then enters the first station steam heater 5 for further heating and temperature increase, and then enters the thermal power station 16 for heat exchange after the pressure is reduced through the pressure reducing turbine unit 12.

[0047] Under this condition, it is necessary to balance the pressure of the original zero-order network and the primary network. Figure 3 Point A is the primary network water supply pressure measurement point, point B is the primary network return water pressure measurement point, point C is the zero network return water pressure measurement point, and point D is the zero network water supply pressure measurement point. The pressure reducing turbine unit 12 is responsible for converting the original water supply pipe pressure P at point D in the figure D Reduce the original water supply pipe pressure P to point A A The return water booster pump 22 is responsible for increasing the original return water pipe pressure P at point B in the figure. B Increase the original return pipe pressure P to point C C ; Potential energy ΔP generated by the decompression of the decompression turbine unit 12 DA It can be fully utilized as the main power source of the return water booster pump 22 to drive the return water booster pump 22 to operate, and the insufficient power is then supplied by the motor.

[0048] Under this working condition, the return booster pump 22 and the first station zero-time network circulation pump 4 are operated in series, the return booster pump 22 adopts the flow feedback control operation mode, and the first station zero-time network circulation pump 4 adopts the outlet constant pressure operation mode. A water replenishment constant pressure buffer water tank 3 is set at the inlet of the first station zero-time network circulation pump 4 to replenish water and maintain pressure, and at the same time absorb the water hammer generated by the return booster pump 22; a bypass is set at the inlet and outlet of the return booster pump 22, and a water hammer check valve 21 is set at the bypass. The water hammer generated by the first station zero-time network circulation pump 4 can also be absorbed by the water replenishment constant pressure buffer water tank 3 after passing through the zero temperature difference bypass water hammer check valve 21.

[0049] In addition, in order to prevent the static pressure of the original primary network from exceeding the design pressure and causing safety accidents, bypass pipes are set at the inlet and outlet of the return water booster pump 22 and a static pressure control pump 23 is configured. When the pressure of the inlet network of the return water booster pump 22 exceeds the limit, the static pressure control pump 23 is started to pump the water leaking from the zero-secondary network to the primary network back to the zero-secondary network pipeline.

[0050] Under this condition, the original zero-time network and the primary network are directly connected, and the return water of the original primary network directly enters the high back pressure condenser 1 after decontamination and pressure increase. The circulating water temperature of the heat network is T C Equal to the return water temperature T of the thermal power station B , that is, the return water temperature of the primary network is equal to the return water temperature of the zero-order network.

[0051] Generally, when the heat load is low (less than 70% of the design heat load) or the return water temperature of the primary network heating network is low (the temperature rise in the high back pressure condenser is less than 8°C), the system operates under normal conditions; when the heat load is high (greater than 70% of the design heat load) or the return water temperature of the primary network heating network is high (the temperature rise in the high back pressure condenser is greater than 8°C), the system operates under the zero temperature drop condition of the pressure isolation station.

[0052] The above descriptions are merely embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by technicians familiar with the technical field within the technical scope disclosed by the present invention, or equivalent structures or equivalent process transformations made using the contents of the present invention specification and drawings, or direct or indirect applications in other related technical fields, should all be covered within the protection scope of the present invention.

Claims

1. A zero-temperature drop heating system for a pressure isolation station based on a high back pressure unit, characterized in that: It includes a high back pressure condenser (1), a first station zero network circulation pump (4), a first station steam heater (5), a pressure reducing turbine unit (12), a thermal power station (16), a pressure isolation station primary network circulation pump (18), a return water booster pump (22) and a pressure isolation station plate heat exchanger (24); The high temperature side outlet of the plate heat exchanger (24) of the pressure isolation station is connected to the water side inlet of the high back pressure condenser (1), and the water side outlet of the high back pressure condenser (1) is connected to the inlet of the zero-order network circulation pump (4) of the first station; the outlet of the zero-order network circulation pump (4) of the first station is connected to the water side inlet of the steam heater (5) of the first station; the water side outlet of the steam heater (5) of the first station is respectively connected to the high temperature side inlet of the pressure reducing turbine unit (12) and the plate heat exchanger (24) of the pressure isolation station; the outlet of the pressure reducing turbine unit (12) is connected to the hot water inlet of the first station steam heater (5); The high-temperature side inlet of the power station (16) is connected; the low-temperature side outlet of the plate heat exchanger (24) of the pressure isolation station is connected to the high-temperature side inlet of the thermal power station (16); the high-temperature side outlet of the thermal power station (16) is respectively connected to the inlet of the primary network circulation pump (18) of the pressure isolation station and the inlet of the return water booster pump (22); the outlet of the primary network circulation pump (18) of the pressure isolation station is connected to the low-temperature side inlet of the plate heat exchanger (24) of the pressure isolation station; the outlet of the return water booster pump (22) is connected to the water side inlet of the high back pressure condenser (1); Normal working conditions: When the heat load or the return water temperature of the primary network heat network is lower than the preset value, the pressure reducing turbine unit (12) and the return water booster pump (22) are not put into operation, and the plate heat exchanger (24) of the pressure isolation station divides the system into the zero-time network and the primary network; on the zero-time network side, the heat network circulating water first enters the high back pressure condenser (1) for heating, and then enters the first station steam heater (5) for further heating and temperature increase, and the circulation power is provided by the first station zero-time network circulation pump (4); on the primary network side, the low-temperature side outlet water of the plate heat exchanger (24) of the pressure isolation station goes to the thermal power station (16) through the water supply pipeline, and after releasing heat, returns to the low-temperature side inlet of the plate heat exchanger (24) of the pressure isolation station from the return water pipeline to carry out the next heat exchange cycle, and the circulation power is provided by the primary network circulation pump (18) of the pressure isolation station; the temperature of the heat network circulating water entering the high back pressure condenser (1) is greater than the return water temperature of the thermal power station (16); Zero temperature drop condition of pressure isolation station: When the heat load or the return water temperature of the primary network is higher than the preset value, the plate heat exchanger (24) of the pressure isolation station is not put into operation; the zero-secondary network and the primary network are directly connected, and the return water of the thermal power station (16) enters the high back pressure condenser (1) for heating through the return water booster pump (22), and then enters the first station steam heater (5) for further heating and temperature increase, and then enters the thermal power station (16) for heat exchange after being reduced in pressure by the pressure reducing turbine unit (12); the temperature of the thermal network circulating water entering the high back pressure condenser (1) is equal to the return water temperature of the thermal power station (16); Under the zero temperature drop condition of the pressure isolation station, the pressure reducing turbine unit (12) reduces the zero-secondary network water supply pressure to the primary network water supply pressure, and the return water booster pump (22) increases the primary network return water pressure to the zero-secondary network return water pressure.

2. The zero-temperature drop heating system for the pressure isolation station based on the high back pressure unit according to claim 1 is characterized in that: The inlet of the first station zero-time network circulation pump (4) is connected to a water replenishment constant pressure buffer water tank (3).

3. The zero-temperature drop heating system for the pressure isolation station based on the high back pressure unit according to claim 1 is characterized in that: A #3 gate valve (10) is provided between the high-temperature side outlet of the plate heat exchanger (24) of the pressure isolation station and the water side inlet of the high back pressure condenser (1), a #1 gate valve (7) is provided between the water side outlet of the steam heater (5) of the first station and the pressure reducing turbine unit (12), a #2 gate valve (8) is provided between the water side outlet of the steam heater (5) of the first station and the high-temperature side inlet of the plate heat exchanger (24) of the pressure isolation station, and a #5 gate valve (13) is provided between the outlet of the pressure reducing turbine unit (12) and the high-temperature side inlet of the thermal power station (16). ), a #6 gate valve (14) is provided between the low-temperature side outlet of the plate heat exchanger (24) of the pressure isolation station and the high-temperature side inlet of the thermal power station (16), a #7 gate valve (17) is provided between the high-temperature side outlet of the thermal power station (16) and the inlet of the primary network circulation pump (18) of the pressure isolation station, a #8 gate valve (19) is provided between the high-temperature side outlet of the thermal power station (16) and the inlet of the return water booster pump (22), and a #4 gate valve (11) is provided between the outlet of the return water booster pump (22) and the water side inlet of the high back pressure condenser (1).

4. The zero-temperature drop heating system for the pressure isolation station based on the high back pressure unit according to claim 1 is characterized in that: A #1 regulating valve (2) is connected between the water side inlet and the water side outlet of the high back pressure condenser (1), a #2 regulating valve (6) is connected between the water side inlet and the water side outlet of the first station steam heater (5), a #3 regulating valve (9) is connected between the high temperature side inlet and the high temperature side outlet of the pressure isolation station plate heat exchanger (24), and a #4 regulating valve (15) is connected between the low temperature side inlet and the low temperature side outlet of the pressure isolation station plate heat exchanger (24).

5. The zero-temperature drop heating system for the pressure isolation station based on the high back pressure unit according to claim 1 is characterized in that: A dirt remover (20) is provided between the high-temperature side outlet of the thermal power station (16) and the inlet of the return water booster pump (22).

6. The zero-temperature drop heating system for the pressure isolation station based on the high back pressure unit according to claim 1 is characterized in that: Two bypasses are provided between the inlet and the outlet of the return water booster pump (22), one bypass is provided with a water hammer prevention check valve (21), and the other bypass is provided with a static pressure control pump (23).

7. The working method of the zero-temperature drop heating system of the pressure isolation station based on the high back pressure unit according to any one of claims 1 to 6, characterized in that: include: Normal working conditions: When the heat load or the return water temperature of the primary network heat network is lower than the preset value, the pressure reducing turbine unit (12) and the return water booster pump (22) are not put into operation, and the plate heat exchanger (24) of the pressure isolation station divides the system into the zero-time network and the primary network; on the zero-time network side, the heat network circulating water first enters the high back pressure condenser (1) for heating, and then enters the first station steam heater (5) for further heating and temperature increase, and the circulation power is provided by the first station zero-time network circulation pump (4); on the primary network side, the low-temperature side outlet water of the plate heat exchanger (24) of the pressure isolation station goes to the thermal power station (16) through the water supply pipeline, and after releasing heat, returns to the low-temperature side inlet of the plate heat exchanger (24) of the pressure isolation station from the return water pipeline to carry out the next heat exchange cycle, and the circulation power is provided by the primary network circulation pump (18) of the pressure isolation station; the temperature of the heat network circulating water entering the high back pressure condenser (1) is greater than the return water temperature of the thermal power station (16); Zero temperature drop condition of pressure isolation station: When the heat load or the return water temperature of the primary network is higher than the preset value, the plate heat exchanger (24) of the pressure isolation station is not put into operation; the zero-secondary network and the primary network are directly connected, and the return water of the thermal power station (16) enters the high back pressure condenser (1) for heating through the return water booster pump (22), and then enters the first station steam heater (5) for further heating and temperature increase, and then enters the thermal power station (16) for heat exchange after being reduced in pressure by the pressure reducing turbine unit (12); the temperature of the thermal network circulating water entering the high back pressure condenser (1) is equal to the return water temperature of the thermal power station (16).

8. The working method of the zero-temperature drop heating system of the pressure isolation station based on the high back pressure unit according to claim 7 is characterized in that: Under normal operating conditions, the first station zero-order network circulation pump (4) and the pressure isolation station primary network circulation pump (18) both adopt the inlet constant pressure operation mode; under the zero temperature drop operating condition of the pressure isolation station, the first station zero-order network circulation pump (4) and the return water booster pump (22) are operated in series, and the first station zero-order network circulation pump (4) adopts the outlet constant pressure operation mode, and the return water booster pump (22) adopts the flow feedback control operation mode.

9. The working method of the zero-temperature drop heating system of the pressure isolation station based on the high back pressure unit according to claim 7 is characterized in that: Under the zero temperature drop condition of the pressure isolation station, the pressure reducing turbine unit (12) reduces the zero-secondary network water supply pressure to the primary network water supply pressure, and the return water booster pump (22) increases the primary network return water pressure to the zero-secondary network return water pressure.

10. The working method of the zero-temperature drop heating system of the pressure isolation station based on the high back pressure unit according to claim 7, characterized in that: Under the zero temperature drop condition of the pressure isolation station, the potential energy generated by the pressure reduction of the pressure reducing turbine unit (12) drives the return water booster pump (22), and the insufficient power is then supplied by the motor.

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