Energy system for sewage treatment plant and operation control method

Abstract

According to the energy system for the sewage treatment plant and the operation control method, an internal combustion engine system uses biogas generated by an anaerobic biochemical pool as a raw material, passes through a biogas collecting device and then is fed into an internal combustion engine for combustion power generation, and power is supplied to a plant area and equipment; high-temperature flue gas generated in the running process of the internal fuel gas and waste heat in the cylinder sleeve water are subjected to heat exchange through the flue gas-cylinder sleeve water heat exchanger, and water obtained after heat exchange is supplied to tail end domestic water and user side heating through the second-stage heat exchanger. The sewage source heat pump system supplies sewage treatment secondary water in a plant area to the sewage source heat pump unit for heat exchange, cold and heat are supplied to end users, and the system and the internal combustion engine system complement each other and are used for supplying heat to the user side. The energy system for the sewage treatment plant and the operation control method are established, energy media in the sewage treatment process are utilized, comprehensive utilization of energy is achieved, the problem of high energy consumption of the sewage treatment plant can be better solved, and obvious energy conservation and emission reduction effects are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of comprehensive energy utilization and relates to an energy system and an operation control method for a sewage treatment plant. Background Art

[0002] During the sewage treatment process, a large amount of methane-rich biogas is produced in the anaerobic tank. If this biogas is directly discharged into the atmosphere, it will not only cause a waste of resources, but also aggravate the greenhouse effect. Therefore, effectively collecting and utilizing biogas through biogas internal combustion engines can provide electricity and heat for sewage treatment plants.

[0003] The sewage temperature is constant during the sewage treatment process, and the water temperature in winter and summer is kept within a certain range compared to the air temperature all year round. The secondary sewage effluent temperature is generally 12℃~14℃ in winter, about 10℃ higher than the air temperature, and 27℃~28℃ in summer, about 10℃ lower than the air temperature. Therefore, sewage can be used as a heat source for the heat pump system. Using the heat energy in sewage for cooling and heating the sewage treatment plant can improve energy efficiency, while reducing carbon dioxide emissions and air pollution.

[0004] How to utilize and complement the energy media in the above two types of sewage treatment plants to maximize energy utilization, solve the high energy consumption of sewage treatment plants, and improve the energy self-sufficiency rate and economic benefits of sewage treatment plants are the key issues to be solved at present. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an energy system and an operation control method for a sewage treatment plant to provide electricity, cooling / heating and domestic hot water for the user side, maximize the utilization of biogas energy and sewage, reduce greenhouse gas emissions, and improve the energy self-sufficiency rate and economic benefits of the sewage treatment plant.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: an energy system for a sewage treatment plant, which includes a biogas internal combustion circuit, a heat exchange circuit and a sewage source heat circuit; the water-water heat exchanger in the biogas internal combustion circuit is connected to the heat exchange circuit, and the sewage source heat circuit is connected to the heat exchange circuit; the biogas internal combustion circuit includes an anaerobic biochemical tank and a biogas internal combustion engine connected to a biogas collection device, and the outlet side of the biogas internal combustion engine is connected to a flue gas-cylinder jacket water heat exchanger, a water-water heat exchanger and a cylinder jacket water pump in sequence, the cylinder jacket water pump is connected to the return side of the biogas internal combustion engine, and the cylinder jacket water pump is also electrically connected to the cylinder jacket water pump controller; the output end of the biogas internal combustion engine faces the power sales grid and the user side power supply, and the sewage source heat circuit faces the user side cooling / heating; the biogas internal combustion circuit is coupled to the sewage source heat circuit.

[0007] The heat exchange circuit includes a water-water heat exchanger water pump, a heat collecting tank, a diverter A, an electric heating boiler, a combiner A, a diverter B and a combiner B which are sequentially connected on the outlet side of the water-water heat exchanger; the combiner B is connected to the return side of the water-water heat exchanger.

[0008] One outlet side of the diverter B is connected to the domestic hot water on the user side and then communicated with the combiner B, and the other outlet side of the diverter B is connected to the heating on the user side and then communicated with the combiner B.

[0009] The water collecting water tank, diverter A and electric heating boiler are electrically connected to the supplementary heat controller; the water-water heat exchanger water pump is electrically connected to the water-water heat exchanger water pump controller; and the diverter B is electrically connected to the diverter controller.

[0010] The branch pipeline led out between the heat collecting tank and the diverter A is connected to the sewage source heat circuit, and the user-side cooling / heating in the sewage source heat circuit is connected to the user-side heating; a hot water supplement pump is arranged in the branch pipeline.

[0011] The sewage source heat circuit includes a sewage collection device and user-side cooling / heating connected to a sewage source heat pump; the sewage source heat pump includes a sewage source heat pump throttle valve, a sewage source heat pump condenser and a sewage source heat pump compressor connected in series in sequence to form a circulation loop.

[0012] The sewage source heat pump evaporator is connected to the sewage collecting device to form a loop, a sewage side water pump is arranged in the loop, and the loop is connected to the heat exchange loop.

[0013] The sewage source heat pump condenser is connected to the user-side cooling / heating to form a loop, in which a user-side water pump is arranged.

[0014] A four-way reversing valve is arranged in the pipeline between the throttle valve of the sewage source heat pump and the condenser of the sewage source heat pump.

[0015] The operation control method for the energy system of a sewage treatment plant as described above comprises the following steps: S1, the biogas collection device collects the biogas generated from the anaerobic biochemical tank and sends it to the biogas internal combustion engine for combustion; the high-temperature flue gas and cylinder jacket water generated after combustion are heat exchanged through the flue gas-cylinder jacket water heat exchanger; S2, the biogas internal combustion loop provides domestic hot water and winter heating for the user side, and also supplements the heat for the sewage source heat pump side through the water-water heat exchanger water pump through the heat collection tank, and generates electricity through the biogas internal combustion engine to meet the user side's electrical load demand. When the power generation is greater than the demand, the surplus power is sold to the grid; S3, the sewage source heat loop exchanges heat between the physically and chemically treated secondary water from the sewage treatment plant and the sewage source heat pump evaporator, and exchanges heat between the user side and the sewage source heat pump condenser to provide cooling or heating for the user; when the sewage heat is insufficient, the heat collection tank supplements the heat; S4, when the water level in the heat collection tank is insufficient, tap water is used for water replenishment; S5, when the hot water temperature of the electric heating boiler does not meet the set water supply temperature, the electric heating boiler starts heating to the set temperature; S6, when switching between winter and summer, the four-way reversing valve in the sewage source heat pump switches the refrigerant flow direction, and heat exchange is performed through the sewage source heat pump evaporator and the sewage source heat pump condenser to achieve switching between cooling and heating; S7, when the sewage volume is insufficient or the sewage inlet temperature is low, the biogas internal combustion engine is used to supplement the heat; S8, the jacket water pump controller controls the jacket water circulation flow rate, and when there is no heating demand, reduces the jacket water flow rate; S9, the water-water heat exchanger pump controller controls the flow on the water-water side. The demand for heating and domestic hot water in winter is different from that in non-winter, so the flow in different time periods is controlled; S10, the flow divider A and the flow divider B divide the required flow rates of heating and domestic hot water through the flow divider according to the different required flow rates of heating and domestic hot water; S11, the supplementary heat controller controls the water supply temperature fed back from the heat collecting tank. When the set temperature is reached, the diversion ratio of the diverter is controlled, and at the same time, the electric heating boiler is controlled to start to reach the set water supply temperature.

[0016] The main beneficial effects of the present invention are: Utilizing energy media in the sewage treatment process to achieve comprehensive energy utilization can better solve the problem of high energy consumption in sewage treatment plants and has obvious energy-saving and emission-reduction effects.

[0017] Compared with the traditional sewage source heat pump, the biogas internal combustion engine system coupled with the sewage source heat pump system can provide cooling, heating and electricity for the user side. It is a comprehensive energy system with comprehensive resource utilization and improved energy utilization efficiency. To a certain extent, it can significantly reduce carbon emissions and greenhouse gas emissions, and play a positive role in alleviating global warming.

[0018] Through various levels of control, including jacket water pump control, water-water heat exchanger pump control, diverter control, and supplementary heat boiler control, it is possible to maximize energy utilization and humanize system settings to reduce energy waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0020] Figure 1 It is a system diagram of the present invention.

[0021] Figure 2 This is a control diagram of the present invention.

[0022] Figure 3 It is a flow chart of the electric heating operation mode of the present invention.

[0023] Figure 4 It is a flow chart of the heat-to-electricity operation mode of the present invention.

[0024] In the figure: anaerobic biochemical pool 1, biogas collection device 2, biogas internal combustion engine 3, flue gas-cylinder jacket water heat exchanger 4, water-water heat exchanger 5, cylinder jacket water pump 6, water-water heat exchanger pump 7, water collecting tank 8, diverter A9, electric heating boiler 10, combiner A11, diverter B12, combiner B13, user-side domestic hot water 14, user-side heating 15, make-up heat controller 16, sewage collection device 17, sewage side water pump 18, make-up hot water pump 19, sewage source heat pump 20, sewage source heat pump evaporator 21, sewage source heat pump throttle valve 22, sewage source heat pump condenser 23, sewage source heat pump compressor 24, four-way reversing valve 25, user-side water pump 26, electricity sales to the grid 27, user-side power supply 28, user-side cooling / heating 29, cylinder jacket water pump controller 30, water-water heat exchanger pump controller 31, diverter controller 32. DETAILED DESCRIPTION

[0025] like Figure 1~Figure 4 In the invention, an energy system for a sewage treatment plant comprises a biogas internal combustion circuit, a heat exchange circuit and a sewage source heat circuit; a water-water heat exchanger 5 in the biogas internal combustion circuit is connected to the heat exchange circuit, and a sewage source heat circuit is connected to the heat exchange circuit; the biogas internal combustion circuit comprises an anaerobic biochemical tank 1 and a biogas internal combustion engine 3 connected to a biogas collection device 2, an outlet side of the biogas internal combustion engine 3 is sequentially connected to a flue gas-cylinder jacket water heat exchanger 4, a water-water heat exchanger 5 and a cylinder jacket water pump 6, the cylinder jacket water pump 6 is connected to a reflux side of the biogas internal combustion engine 3, and the cylinder jacket water pump 6 is also electrically connected to a cylinder jacket water pump controller 30; an output end of the biogas internal combustion engine 3 faces a power supply grid 27 and a user-side power supply 28, and a sewage source heat circuit faces a user-side cooling / heating 29; the biogas internal combustion circuit is coupled to the sewage source heat circuit.

[0026] The heat exchange circuit includes a water-water heat exchanger water pump 7, a heat collecting tank 8, a diverter A9, an electric heating boiler 10, a combiner A11, a diverter B12 and a combiner B13 which are sequentially connected on the outlet side of the water-water heat exchanger 5; the combiner B13 is connected to the reflux side of the water-water heat exchanger 5.

[0027] One outlet side of the diverter B12 is connected to the user-side domestic hot water 14 and then communicated with the combiner B13, and the other outlet side of the diverter B12 is connected to the user-side heating 15 and then communicated with the combiner B13.

[0028] The water collecting tank 8, diverter A9 and electric heating boiler 10 are electrically connected to the supplementary heat controller 16; the water-water heat exchanger water pump 7 is electrically connected to the water-water heat exchanger water pump controller 31; and the diverter B12 is electrically connected to the diverter controller 32.

[0029] The branch pipeline extending between the heat collecting tank 8 and the diverter A9 is connected to the sewage source heat circuit, and the user-side cooling / heating 29 in the sewage source heat circuit is connected to the user-side heating 15; a hot water supplement pump 19 is provided in the branch pipeline.

[0030] The sewage source heat circuit includes a sewage collection device 17 and a user-side cooling / heating 29 connected to a sewage source heat pump 20; the sewage source heat pump 20 includes a sewage source heat pump evaporator 21, a sewage source heat pump throttle valve 22, a sewage source heat pump condenser 23 and a sewage source heat pump compressor 24 connected in series in sequence to form a circulation loop.

[0031] The sewage source heat pump evaporator 21 is connected to the sewage collecting device 17 to form a loop, in which a sewage side water pump 18 is arranged, and the loop is connected to the heat exchange loop.

[0032] The sewage source heat pump condenser 23 is connected to the user-side cooling / heating 29 to form a loop, and a user-side water pump 26 is provided in the loop.

[0033] A four-way reversing valve 25 is provided in the pipeline between the sewage source heat pump throttle valve 22 and the sewage source heat pump condenser 23 .

[0034] Embodiment 1, Reference Figure 1 The energy system includes an anaerobic biochemical pool 1, a biogas collection device 2, a biogas internal combustion engine 3, a flue gas-cylinder jacket water heat exchanger 4, a water-water heat exchanger 5, a cylinder jacket water pump 6, a water-water heat exchanger pump 7, a heat collecting tank 8, a diverter A9, an electric heating boiler 10, a combiner A11, a diverter B12, a combiner B13, user-side domestic hot water 14, user-side heating 15, a supplementary heat controller 16, a sewage collection device 17, a sewage side water pump 18, a supplementary hot water pump 19, a sewage source heat pump 20, a sewage source heat pump evaporator 21, a sewage source heat pump throttle valve 22, a sewage source heat pump condenser 23, a sewage source heat pump compressor 24, a four-way reversing valve 25, a user-side water pump 26, electricity sales to the grid 27, user-side power supply 28, user-side cooling / heating 29, a cylinder jacket water pump controller 30, a water-water heat exchanger pump controller 31, and a diverter controller 32.

[0035] The energy system is formed by coupling a biogas internal combustion engine system and a sewage source heat pump system. The biogas internal combustion engine system consists of an anaerobic biochemical tank 1, a biogas collection device 2, a biogas internal combustion engine 3, a flue gas-cylinder jacket water heat exchanger 4, a water-water heat exchanger 5, a cylinder jacket water pump 6, a water-water heat exchanger pump 7, a water collecting tank 8, a diverter A9, an electric heating boiler 10, a combiner A11, a diverter B12, a combiner B13, a user-side domestic hot water 14, a user-side heating 15, a supplementary heat controller 16, a sewage collection device 17, a user-side water pump 18 and a supplementary hot water pump 19 to form a cycle, providing the user-side domestic hot water 14, the user-side heating 15 and the user-side power supply 28, and when there is surplus electricity, it can sell electricity to the grid 27.

[0036] The sewage source heat pump system consists of a sewage collection device 17, a sewage side water pump 18, a sewage source heat pump evaporator 21, a sewage source heat pump throttle valve 22, a sewage source heat pump condenser 23, a sewage source heat pump compressor 24, a four-way reversing valve 25, and a user side water pump 26 to form a cycle to provide cooling / heating 29 for the user side.

[0037] The operation control method for the energy system of a sewage treatment plant as described above comprises the following steps: S1, the biogas collecting device 2 collects the biogas generated from the anaerobic biochemical tank 1 and sends it to the biogas internal combustion engine 3 for combustion; the high-temperature flue gas and cylinder jacket water generated after combustion are heat exchanged through the flue gas-cylinder jacket water heat exchanger 4; S2, the biogas internal combustion loop provides domestic hot water and winter heating for the user side, and also exchanges heat through the water-water heat exchanger pump 7 and then passes through the water collection tank 8 to supplement the heat for the sewage source heat pump 20 side, and generates electricity through the biogas internal combustion engine 3 to meet the user side's electrical load demand. When the power generation is greater than the demand, the surplus electricity is sold to the grid; S3, the sewage source heat circuit exchanges heat with the sewage source heat pump evaporator 21 after physical and chemical treatment from the sewage treatment plant, and exchanges heat with the sewage source heat pump condenser 23 on the user side to provide cooling or heating for the user; when the sewage heat is insufficient, the heat collecting tank 8 supplements the heat; S4, when the water level in the heat collection tank 8 is insufficient, tap water is used for water replenishment; S5, when the hot water temperature of the electric heating boiler 10 does not meet the set water supply temperature, the electric heating boiler 10 starts heating to the set temperature; S6, when switching between winter and summer, the four-way reversing valve 25 in the sewage source heat pump 20 switches the refrigerant flow direction, and heat exchange is performed through the sewage source heat pump evaporator 21 and the sewage source heat pump condenser 23 to realize the switching between cooling and heating; S7, when the sewage volume is insufficient or the sewage inlet temperature is low, the biogas internal combustion engine 3 is used to supplement heat; S8, the jacket water pump controller 30 controls the jacket water circulation flow rate, and when there is no heating demand, reduces the jacket water flow rate; S9, the water-water heat exchanger pump controller 31 controls the water-water side flow rate. The winter demand for heating and domestic hot water is different from the non-winter demand flow rate, and the flow rate in different time periods is controlled; S10, the flow divider A9 and the flow divider B12 divide the required flow rates of heating and domestic hot water through the flow dividers according to the different required flow rates of heating and domestic hot water; S11, the supplementary heat controller 16 controls the water collection tank 8 to feedback the water supply temperature. When the set temperature is reached, the diversion ratio of the diverter is controlled, and the electric heating boiler 10 is controlled to start to reach the set water supply temperature.

[0038] Embodiment 2, Reference Figure 2 The main operation control method is as follows: the biogas collection device collects the biogas generated from the anaerobic biochemical tank and sends it to the biogas internal combustion engine for combustion. The biogas internal combustion engine can supply power to the user side, and the surplus power can be sold online. The flue gas and cylinder jacket water generated by the internal combustion engine can use the remaining heat to exchange heat through the flue gas-cylinder jacket water heat exchanger, and then further heat exchange through the water-water heat exchanger. The above two heat exchanges are hot water circulation.

[0039] After heat exchange in the water-water heat exchanger, the water is pumped into the water collection tank through the water-water heat exchanger. The water collection tank is divided into two paths after the diverter, and one path is sent to the electric heating boiler. After the electric heating boiler, it merges with the outlet of the water collection tank. The function of the electric heating boiler here is to supplement the hot water. After the confluence, it is connected to the diverter and divided into two water supply paths, one for domestic hot water on the user side, and the other for winter heating on the user side. After the two paths are merged, they are sent to the water collection tank to form a hot water cycle.

[0040] The above-mentioned biogas internal combustion engine system cycle control is as follows: the jacket water pump controller controls the jacket water pump, and calculates the hourly flow of the jacket water pump through the hourly domestic hot water flow on the user side and the hot water flow for heating on the user side, and inputs it into the jacket water pump controller to control the pump power and reduce energy consumption. Similarly, the water-water heat exchanger pump controller controls the water-water heat exchanger pump, and calculates the hourly flow of the water-water heat exchanger pump through the hourly domestic hot water flow on the user side and the hot water flow for heating on the user side, and inputs it into the water-water heat exchanger pump controller to control the pump power and reduce energy consumption. The diverter controller controls the domestic hot water flow on the user side and the hot water flow for heating in winter, and controls the diverter control ratio by inputting the domestic hot water flow on the user side and the hourly flow of heating in winter on the user side.

[0041] The function of the supplementary heating boiler controller is to heat the circulating hot water. When the hot water temperature in the heat collection tank is not enough to meet the set hot water temperature, the heat collection tank will feed back to the supplementary heating boiler controller to control the opening of the diverter. At the same time, the controller controls the electric heating boiler to start heating the hot water.

[0042] The circulation control of the above-mentioned sewage source heat pump system is as follows: the sewage collection device collects sewage from secondary treatment, the sewage secondary water exchanges heat with the sewage source heat pump evaporator, and the user side exchanges heat with the sewage source heat pump condenser to provide cooling or heating for the user. Cooling in summer and heating in winter can be achieved through a four-way reversing valve to switch the flow direction of the refrigerant. The sewage secondary water, sewage test water pump, and sewage source heat pump evaporator are connected in sequence to form a sewage side cycle; the sewage source heat pump condenser, user side water pump, and user side are connected in sequence to form a user side cycle. In addition, when the sewage is insufficient, the heat collection tank can supplement the heat. When operating in winter, the sewage source heat pump can provide additional heating for the user side.

[0043] Embodiment 3, like Figure 3 and Figure 4 The feasible operation modes of the biogas internal combustion engine system include "electricity determines heat" and "heat determines electricity" operation modes based on the above biogas internal combustion engine system.

[0044] "Electricity determines heat" operation mode: the capacity of the biogas internal combustion engine is determined according to the electricity load of the sewage treatment plant, giving priority to meeting the electricity load demand on the user side of the plant, and recovering the waste heat generated by power generation to meet the heat load demand on the user side. When the recovered heat cannot meet the heat load demand on the user side, it is supplemented by an electric heating boiler. When the recovered heat is greater than the heat load demand on the user side, it can be stored through a heat storage device.

[0045] "Electricity based on heat" operation mode: the capacity of the biogas internal combustion engine is determined according to the heat load of the sewage treatment plant, giving priority to meeting the heat load demand on the user side, and recovering the waste heat generated by power generation to fully meet the heat load demand of the user. When the power generation cannot meet the demand, the system purchases electricity from the power grid to meet the power load. When there is surplus power generation, the surplus electricity is sold to the power grid through "going online".

[0046] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations of the present invention. The embodiments and features in the embodiments of the present application can be arbitrarily combined with each other without conflict. The protection scope of the present invention shall be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. An energy system for a sewage treatment plant, characterized by: It comprises a biogas internal combustion circuit, a heat exchange circuit and a sewage source heat circuit; the water-water heat exchanger (5) in the biogas internal combustion circuit is connected to the heat exchange circuit, and the sewage source heat circuit is connected to the heat exchange circuit; the biogas internal combustion circuit comprises an anaerobic biochemical tank (1) and a biogas internal combustion engine (3) connected to a biogas collection device (2); the outlet side of the biogas internal combustion engine (3) is connected in sequence to a flue gas-cylinder jacket water heat exchanger (4), a water-water heat exchanger (5) and a cylinder jacket water pump (6); the cylinder jacket water pump (6) is connected to the return side of the biogas internal combustion engine (3), and the cylinder jacket water pump (6) is also electrically connected to a cylinder jacket water pump controller (30); the output end of the biogas internal combustion engine (3) faces the electricity sales grid (27) and the user side power supply (28), and the sewage source heat circuit faces the user side cooling / heating (29); the biogas internal combustion circuit is coupled to the sewage source heat circuit.

2. The energy system for a sewage treatment plant according to claim 1, characterized in that: The heat exchange circuit comprises a water-water heat exchanger water pump (7), a heat collecting tank (8), a diverter A (9), an electric heating boiler (10), a combiner A (11), a diverter B (12) and a combiner B (13) which are connected in sequence on the outlet side of the water-water heat exchanger (5); the combiner B (13) is connected to the return side of the water-water heat exchanger (5).

3. The energy system for a sewage treatment plant according to claim 2, characterized in that: One outlet side of the diverter B (12) is connected to the domestic hot water (14) on the user side and then communicated with the combiner B (13), and the other outlet side of the diverter B (12) is connected to the heating (15) on the user side and then communicated with the combiner B (13).

4. The energy system for a sewage treatment plant according to claim 2, characterized in that: The heat collecting tank (8), the diverter A (9) and the electric heating boiler (10) are electrically connected to the supplementary heat controller (16); the water-to-water heat exchanger pump (7) is electrically connected to the water-to-water heat exchanger pump controller (31); and the diverter B (12) is electrically connected to the diverter controller (32).

5. The energy system for a sewage treatment plant according to claim 2, characterized in that: The branch pipeline extending between the heat collecting tank (8) and the diverter A (9) is connected to the sewage source heat circuit, and the user-side cooling / heating (29) in the sewage source heat circuit is connected to the user-side heating (15); a hot water supplement pump (19) is provided in the branch pipeline.

6. The energy system for a sewage treatment plant according to claim 1, characterized in that: The sewage source heat circuit comprises a sewage collection device (17) and a user-side cooling / heating (29) connected to a sewage source heat pump (20); the sewage source heat pump (20) comprises a sewage source heat pump evaporator (21), a sewage source heat pump throttle valve (22), a sewage source heat pump condenser (23) and a sewage source heat pump compressor (24) which are sequentially connected in series to form a circulation loop.

7. The energy system for a sewage treatment plant according to claim 6 is characterized in that: The sewage source heat pump evaporator (21) is connected to the sewage collection device (17) to form a loop, a sewage side water pump (18) is provided in the loop, and the loop is connected to the heat exchange loop.

8. The energy system for a sewage treatment plant according to claim 6, characterized in that: The sewage source heat pump condenser (23) is connected to the user-side cooling / heating (29) to form a loop, in which a user-side water pump (26) is provided.

9. The energy system for a sewage treatment plant according to claim 6, characterized in that: A four-way reversing valve (25) is provided in the pipeline between the sewage source heat pump throttle valve (22) and the sewage source heat pump condenser (23).

10. The operation control method for the energy system of a sewage treatment plant according to any one of claims 1 to 9, characterized in that: The steps include: S1, the biogas collecting device (2) collects the biogas generated from the anaerobic biochemical tank (1) and sends it to the biogas internal combustion engine (3) for combustion; the high-temperature flue gas and cylinder jacket water generated after the combustion are heat exchanged through the flue gas-cylinder jacket water heat exchanger (4); S2, the biogas internal combustion circuit provides domestic hot water and winter heating for the user side, and also exchanges heat through the water-to-water heat exchanger pump (7) and the heat collector (8) for the sewage source heat pump (20) side to supplement the heat. The biogas internal combustion engine (3) generates electricity to meet the user side's electrical load demand. When the power generation is greater than the demand, the surplus electricity is sold to the grid; S3, the sewage source heat circuit exchanges heat between the physically and chemically treated secondary water from the sewage treatment plant and the sewage source heat pump evaporator (21), and exchanges heat between the user side and the sewage source heat pump condenser (23), so as to provide cooling or heating for the user; when the sewage heat is insufficient, the heat collecting tank (8) supplements the heat; S4, when the water level in the heat collecting tank (8) is insufficient, tap water is used for replenishment; S5, when the hot water temperature of the electric heating boiler (10) does not meet the set water supply temperature, the electric heating boiler (10) starts heating to the set temperature; S6, when switching between winter and summer, the four-way reversing valve (25) in the sewage source heat pump (20) switches the refrigerant flow direction, and heat exchange is performed through the sewage source heat pump evaporator (21) and the sewage source heat pump condenser (23) to achieve switching between cooling and heating; S7, when the sewage volume is insufficient or the sewage inlet temperature is low, the biogas internal combustion engine (3) is used to supplement heat; S8, the jacket water pump controller (30) controls the jacket water circulation flow rate, and when there is no heating demand, reduces the jacket water flow rate; S9, a water-to-water heat exchanger pump controller (31) controls the flow rate on the water-to-water side. The flow rates of heating and domestic hot water demanded in winter are different from those demanded in non-winter, and the flow rates in different time periods are controlled. S10, the flow divider A (9) and the flow divider B (12) divide the required flow rates of heating and domestic hot water through the flow dividers according to the different required flow rates of heating and domestic hot water; S11, the supplementary heat controller (16) controls the water collection tank (8) to feedback the water supply temperature. When the set temperature is reached, the diversion ratio of the diverter is controlled, and at the same time, the electric heating boiler (10) is controlled to start to reach the set water supply temperature.

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