A municipal heating network low-grade waste heat utilization heating system

Abstract

This invention relates to the field of energy engineering technology, specifically to a heating system utilizing low-grade waste heat from municipal heating networks. It solves the problem of decreased efficiency and increased energy consumption in existing water source heat pumps due to low and fluctuating input water temperatures. The heating system includes a water source heat pump supplying heat to users, a heat storage tank, and a municipal heating network return water pipe. The municipal heating network return water pipe supplies heat to the water source heat pump through the municipal heating network supply circuit. The heat storage tank supplies heat to the water source heat pump through its own heat storage circuit. The heat storage tank is connected to the municipal heating network supply circuit through its own heat storage circuit. The heat storage tank regulates the heat storage side temperature of the water source heat pump through both its own heat storage circuit and its own heat storage circuit. The beneficial effects are: the heat storage tank can maximize heat absorption from the return water during off-peak hours and preferentially release high-grade heat during peak hours, thereby smoothing out temporal fluctuations on the heat source side of the heating network and reducing frequent start-ups and shutdowns of the heat pump and the resulting energy consumption and maintenance costs.

Description

Technical Field

[0001] This invention relates to the field of energy engineering technology, and in particular to a heating system for utilizing low-grade waste heat from municipal heating networks. Background Technology

[0002] As a core device for improving the quality of low-grade heat energy, water source heat pumps are widely used in the field of waste heat recovery in municipal heating networks because they can convert low-grade heat sources into high-grade heat energy that meets the heating needs of buildings. However, the water temperature characteristics of low-grade heat sources severely restrict the operating efficiency of water source heat pumps: First, the return water temperature of centralized heating networks is usually maintained in the range of about 30-50℃, which is too low to directly supplement the user-side heat load as a high-temperature heat source; second, due to heat loss caused by long-distance transmission of the pipeline network, load fluctuations during morning and evening heating peaks and off-peak periods, and seasonal climate changes, the return water temperature can fluctuate by 5-10℃ within a single day, and the fluctuation is even higher under extreme conditions. The coefficient of performance (COP) of water source heat pumps is extremely sensitive to the inlet water temperature; and frequent water temperature fluctuations will lead to frequent switching of heat pump operating conditions, aggravating compressor wear, shortening equipment lifespan, and increasing additional energy consumption.

[0003] To address the issue of insufficient heat source stability, the prior art patent CN119983362A discloses a heating system and method that couples a water source heat pump with a seasonal water tank and coordinates with a municipal heating network. This system includes a multi-source coupling system consisting of a solar collector array, a seasonal hot water storage tank, a water source heat pump, and a municipal heating network. It constructs an architecture of "solar energy as the main source, heat pump for efficiency enhancement, and municipal backup." By storing solar energy in the seasonal water tank during the non-heating season, the system switches between direct heating, heat pump-coupled heating, and municipal supplementary heating modes based on the tank temperature during the heating season. This aims to solve the problems of intermittent solar energy and low-grade heat energy utilization after the temperature of the storage body drops.

[0004] While this solution improves the utilization rate of clean energy by combining seasonal hot water storage tanks with heat pumps and incorporates the municipal heating network as a guarantee, it still has significant limitations and cannot specifically address the core problems faced by this invention: First, the solution cannot provide a solution for the problem of low and fluctuating return water temperature; second, the seasonal hot water storage tank is designed to store solar energy across seasons, resulting in a large volume, high construction costs, and a heat storage cycle based on "seasons," making it unable to flexibly respond to daily or short-term fluctuations in the return water temperature of the municipal heating network, and thus difficult to achieve dynamic heat storage and peak shaving.

[0005] In summary, although existing technologies have made some progress in multi-source synergy and cross-seasonal heat storage, none of them can specifically solve the core technical problem of reduced heat pump efficiency and increased energy consumption caused by low and fluctuating input water temperature in water source heat pumps. Utility Model Content

[0006] This utility model proposes a municipal heating network low-grade waste heat utilization heating system, which solves the problem of reduced heat pump efficiency and increased energy consumption caused by low and fluctuating input water temperature in the existing technology.

[0007] The technical solution of this utility model is implemented as follows: A municipal heating network low-grade waste heat utilization heating system includes a water source heat pump that supplies heat to users, a heat storage tank, and a municipal heating network return water pipe. The municipal heating network return water pipe supplies heat to the water source heat pump through the municipal heating network heating circuit. The heat storage tank supplies heat to the water source heat pump through the heat storage tank heating circuit. The heat storage tank is connected to the municipal heating network heating circuit through the heat storage tank heat storage circuit. The heat storage tank regulates the heat storage side temperature of the water source heat pump through the heat storage tank heating circuit and the heat storage tank heat storage circuit.

[0008] The inlet of the water source heat pump on the heat storage side is equipped with a manifold valve, and the water supply pipe in the heat storage tank heating circuit and the municipal heating network heating circuit is connected to the manifold valve. The outlet of the water source heat pump on the heat storage side is equipped with a diverter valve, and the water supply pipe in the heat storage tank heating circuit and the municipal heating network heating circuit is connected to the diverter valve.

[0009] The municipal heating network supply circuit includes a first heat exchanger and a first circulating pump. The heat absorption side of the first heat exchanger is connected to the municipal heating network return water pipe, and the municipal heating network return water pipe is equipped with a heating network circulating pump. The heat release side supply water pipe of the first heat exchanger is connected to the manifold valve through a third supply water valve. The first circulating pump is located between the first heat exchanger and the third supply water valve. The heat release side return water pipe of the first heat exchanger is connected to the diverter valve through a third return water valve.

[0010] The heat storage circuit of the heat storage tank includes a second heat exchanger and a second circulation pump. The heat absorption side water supply pipe of the second heat exchanger is connected to the outlet of the first circulation pump through a first water supply valve. The heat absorption side return water pipe of the second heat exchanger is connected to the heat release side return water pipe of the first heat exchanger through a first return water valve. Both the heat release side water supply pipe and the heat release side return water pipe of the second heat exchanger are connected to the heat storage tank. The second circulation pump is installed on the heat release side water supply pipe of the second heat exchanger.

[0011] The heat storage tank heating circuit includes a third heat exchanger, a third circulating pump, and a fourth circulating pump. The heat absorption side supply pipe and the heat absorption side return pipe of the third heat exchanger are both connected to the heat storage tank. The third circulating pump is installed on the heat absorption side return pipe of the third heat exchanger. The heat release side supply pipe of the third heat exchanger is connected to the manifold valve through the second supply valve. The heat release side return pipe of the third heat exchanger is connected to the diverter valve through the third return valve. The fourth circulating pump is installed between the third return valve and the diverter valve.

[0012] The first, second, and third heat exchangers are all plate heat exchangers.

[0013] The heat release side outlet of the water source heat pump is connected to the user inlet through the user circulation pump, and the user outlet is connected back to the heat release side inlet of the water source heat pump.

[0014] A water source heat pump includes an evaporator, a compressor, a condenser, and a throttling valve connected in sequence. A manifold valve and a distributor valve are connected to the evaporator, and the user inlet and user outlet are connected to the condenser.

[0015] It also includes a system controller and temperature sensors; the temperature sensors include a first temperature sensor located on the top of the heat storage tank, a second temperature sensor located at the inlet of the water source heat pump, a third temperature sensor located indoors at the user's residence, and a fourth temperature sensor located outdoors at the user's residence; the temperature sensors are electrically connected to the system controller to receive temperature signals; the system controller is electrically connected to the heat network circulation pump, the first circulation pump, the second circulation pump, the third circulation pump, the fourth circulation pump, the water source heat pump, and the user circulation pump, respectively, to control the operation of the circulation pumps.

[0016] The beneficial effects of this invention are: the heat storage tank can maximize heat absorption from the return water during the off-peak heating period and preferentially release high-grade heat during the peak heating period, thereby smoothing the temporal fluctuations on the heat source side of the heating network, reducing the frequent start-up and shutdown of the heat pump and the resulting energy consumption and maintenance costs; and the use of heat storage components to undertake emergency backup and buffer functions can provide stable temporary heating when the heating network experiences sudden operating conditions, thereby improving system safety.

[0017] In addition, this system uses municipal return water as a heat source to reduce the direct extraction and discharge of sensitive water bodies such as groundwater, thereby reducing the interference with local hydrology and ecology and providing systematic improvements in terms of environmental impact and engineering economy. The heat storage tank and the heat network work together to increase the temperature of the heat absorption side of the water source heat pump, reduce the temperature difference between the heat absorption side of the water source heat pump and the user, effectively reduce the energy consumption of the water source heat pump, and improve the economy and reliability of the system.

[0018] The heating system can provide a stable heat source in winter for newly built residential areas and areas where it is difficult to renovate or expand municipal heating networks. It effectively alleviates the heat loss problem of water source heat pumps, while reducing energy consumption, improving the energy efficiency ratio, and enhancing the overall stability and service life of the system. It also improves the energy utilization efficiency of municipal heating networks: significantly reducing the return water temperature and increasing the temperature difference between supply and return water, thereby increasing the utilization rate of low-grade heat from thermal power plants, helping to achieve true low-temperature heating and promoting efficient energy recycling. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a heating system for utilizing low-grade waste heat from a municipal heating network, according to the present invention. Figure 2 A water source heat pump heating system that uses the waste heat from the municipal heating network return water as a heat source for heating and supply. Figure 3 A water source heat pump system that uses waste heat from the municipal heating network return water as a heat source for heating and a heat storage tank system for thermal storage and heating. Figure 4 A water source heat pump heating system that uses both waste heat from the municipal heating network return water and heat storage tanks as heat sources; Figure 5 A water source heat pump heating system that uses a heat storage tank as the heat source.

[0021] In the diagram: 1. Municipal heating network return water pipe, 2. Heating network circulation pump, 3. First heat exchanger, 4. First circulation pump, 5. First water supply valve, 6. First return water valve, 7. Second heat exchanger, 8. Second circulation pump, 9. Heat storage tank, 10. Third circulation pump, 11. Third heat exchanger, 12. Second water supply valve, 13. Second return water valve, 14. Fourth circulation pump, 15. Third water supply valve, 16. Third return water valve, 17. Manifold valve, 18. Diverter valve, 19. Evaporator, 20. Compressor, 21. Condenser, 22. Throttling valve, 23. Water source heat pump, 24. User circulation pump. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Example 1, such as Figure 1As shown, a municipal heating network low-grade waste heat utilization heating system includes a water source heat pump 23 for supplying heat to users, a heat storage tank 9, and a municipal heating network return water pipe 1. The municipal heating network return water pipe 1 supplies heat to the water source heat pump 23 through the municipal heating network heating circuit. The heat storage tank 9 supplies heat to the water source heat pump 23 through a heat storage tank heating circuit. The heat storage tank 9 is connected to the municipal heating network heating circuit through a heat storage tank heat storage circuit. The heat storage tank 9 regulates the heat storage side temperature of the water source heat pump 23 through the heat storage tank heating circuit and the heat storage tank heat storage circuit. The water source heat pump 23 absorbs and utilizes the waste heat from the return water in the municipal heating network return water pipe 1 through the municipal heating network heating circuit, increasing the heat storage side temperature of the water source heat pump 23, effectively reducing the energy consumption of the water source heat pump 23, and realizing the effective reuse of the municipal heating network return water, achieving energy saving and environmental protection effects. By adjusting the heat storage tank 9, the temperature fluctuations on the heat storage side of the water source heat pump 23 are effectively balanced, reducing the frequent start-up and shutdown of the heat pump and the resulting energy consumption and maintenance costs. This improves the working efficiency of the water source heat pump 23, reduces its energy consumption, and increases the service life of the compressor in the water source heat pump 23.

[0024] Furthermore, the heat storage side inlet of the water source heat pump 23 is equipped with a manifold valve 17, and the heat storage tank heating circuit and the water supply pipe in the municipal heating network heating circuit are connected to the manifold valve 17. The heat storage side outlet of the water source heat pump 23 is equipped with a diverter valve 18, and the heat storage tank heating circuit and the return water pipe in the municipal heating network heating circuit are connected to the diverter valve 18.

[0025] Furthermore, the municipal heating network supply circuit includes a first heat exchanger 3 and a first circulating pump 4. The heat absorption side of the first heat exchanger 3 is connected to the municipal heating network return water pipe 1, and the municipal heating network return water pipe 1 is equipped with a heating network circulating pump 2. The heat release side supply water pipe of the first heat exchanger 3 is connected to the manifold valve 17 through the third supply water valve 15. The first circulating pump 4 is located between the first heat exchanger 3 and the third supply water valve 15. The heat release side return water pipe of the first heat exchanger 3 is connected to the diversion valve 18 through the third return water valve 16. The heating network circulation pump 2 draws the return water at about 45°C from the municipal heating network return water pipe 1 to the first heat exchanger 3. After heat exchange in the first heat exchanger 3, the temperature decreases, and the cooled return water is re-integrated into the municipal heating network return water pipe 1, realizing the recovery and utilization of low-grade waste heat. After heat exchange in the first heat exchanger 3, the water temperature in the heat release side supply water pipe of the first heat exchanger 3 is about 20°C. The first circulation pump 4 drives the water in the heat release side supply water pipe and the heat release side return water pipe of the first heat exchanger 3 to flow, realizing the transfer of heat to the water source heat pump 23.

[0026] Example 2, based on Example 1, provides a municipal heating network low-grade waste heat utilization heating system. The heat storage tank circuit includes a second heat exchanger 7 and a second circulation pump 8. The heat absorption side supply pipe of the second heat exchanger 7 is connected to the outlet of the first circulation pump 4 through a first supply valve 5. The heat absorption side return pipe of the second heat exchanger 7 is connected to the heat release side return pipe of the first heat exchanger 3 through a first return valve 6. Both the heat release side supply pipe and the heat release side return pipe of the second heat exchanger 7 are connected to the heat storage tank 9. The second circulation pump 8 is installed on the heat release side supply pipe of the second heat exchanger 7. The first circulating pump 4 drives the water in the heat-releasing side supply pipe and the heat-releasing side return pipe of the first heat exchanger 3 to flow. When the first supply valve 5 and the first return valve 6 are opened, part of the water in the heat-releasing side supply pipe of the first heat exchanger 3 will enter the second heat exchanger 7. After heat exchange in the second heat exchanger 7, it will flow back to the first heat exchanger 3. The second circulating pump 8 drives the water in the heat-releasing side supply pipe of the second heat exchanger 7 to flow, which can transfer the heat absorbed at the second heat exchanger 7 to the heat storage tank 9 for heat storage. This process can absorb part of the heat in the municipal heating network heating circuit. When the heat of the municipal heating network return water is excessive, the temperature of the heat storage side of the water source heat pump 23 is reduced, so as to achieve temperature balance of the heat storage side of the water source heat pump 23.

[0027] Furthermore, the heat storage tank heating circuit includes a third heat exchanger 11, a third circulating pump 10, and a fourth circulating pump 14. The heat absorption side supply water pipe and the heat absorption side return water pipe of the third heat exchanger 11 are both connected to the heat storage tank 9. The third circulating pump 10 is installed on the heat absorption side return water pipe of the third heat exchanger 11. The heat release side supply water pipe of the third heat exchanger 11 is connected to the manifold valve 17 through the second supply water valve 12. The heat release side return water pipe of the third heat exchanger 11 is connected to the diverter valve 18 through the third return water valve 13. The fourth circulating pump 14 is provided between the third return water valve 13 and the diverter valve 18. The third circulation pump 10 drives the water in the heat-absorbing side supply pipe of the third heat exchanger 11 to flow, transferring the heat in the heat storage tank 9 to the third heat exchanger 11. The fourth circulation pump 14 drives the water in the heat-releasing side return pipe of the third heat exchanger 11 to flow, transferring the heat in the third heat exchanger 11 to the inlet of the water source heat pump 23. During this process, the heat in the municipal heating network supply circuit is supplemented. When the heat in the municipal heating network return water is insufficient, the temperature of the heat storage side of the water source heat pump 23 is increased to achieve temperature balance on the heat storage side of the water source heat pump 23.

[0028] Furthermore, the first heat exchanger 3, the second heat exchanger 7, and the third heat exchanger 11 are all plate heat exchangers.

[0029] Furthermore, the heat release side outlet of the water source heat pump 23 is connected to the user inlet via the user circulation pump 24, and the user outlet is connected back to the heat release side inlet of the water source heat pump 23. After the water source heat pump 23 heats up, it supplies heat to the user through the user circulation pump 24. The water source heat pump 23 includes an evaporator 19, a compressor 20, a condenser 21, and a throttling valve 22 connected in sequence. The manifold valve 17 and the diverter valve 18 are respectively connected to the evaporator 19, and the user inlet and the user outlet are respectively connected to the condenser 21.

[0030] Furthermore, the heating system also includes a system controller and temperature sensors. The temperature sensors include a first temperature sensor located at the top of the heat storage tank 9, a second temperature sensor located at the inlet of the water source heat pump 23, a third temperature sensor located indoors at the user's residence, and a fourth temperature sensor located outdoors at the user's residence. The temperature sensors are electrically connected to the system controller to receive temperature signals. The system controller is electrically connected to the heating network circulation pump 2, the first circulation pump 4, the second circulation pump 8, the third circulation pump 10, the fourth circulation pump 14, the water source heat pump 23, and the user circulation pump 24, respectively, to control the operation of the circulation pumps. Additionally, the system controller is connected to the first water supply valve 5, the first water return valve 6, the second water supply valve 12, the second water return valve 13, the third water supply valve 15, and the third water return valve 16, respectively, and can control the opening and closing of each valve.

[0031] When the municipal heating network supply circuit supplies heat to the water source heat pump 23, the heat storage tank 9 supply circuit inputs heat into the municipal heating network supply circuit, or the heat storage tank storage circuit absorbs heat from the municipal heating network supply circuit. Specifically, the heating system has four operating modes: Mode 1, such as Figure 2 As shown, when the inlet temperature of the water source heat pump 23 is ≥18℃, the municipal heating network supplies heat to the water source heat pump 23 alone. The specific working process is as follows: start the heating network circulation pump 2 and the first circulation pump 4, open the third water supply valve 15 and the third water return valve 16, and close the first water supply valve 5, the first water return valve 6, the second water supply valve 12, and the second water return valve 13; the municipal heating network return water is heated by the first heat exchanger 3, and the water after heat exchange by the first heat exchanger 3 is pushed by the first circulation pump 4 to the manifold valve 17, and then enters the water source heat pump 23. The water source heat pump 23 operates to raise the water temperature to 50~65℃, and then supplies heat to users through the user-side circulation pump 24.

[0032] Mode 2, such as Figure 3As shown, when the municipal heating network provides sufficient heat to the water source heat pipe, i.e., the inlet temperature of the water source heat pump 23 is ≥18℃ and the user-side heat load is low, in this embodiment, the user-side indoor temperature is detected by the third temperature sensor and the user-side outdoor temperature is monitored by the fourth temperature sensor. The temperature difference between the user-side indoor and outdoor temperatures is calculated to determine the user's heat load. When the temperature difference between the user-side indoor and outdoor temperatures is small, the user-side heat load is low. At this time, the municipal heating network water supply pipe 1 transfers the excess heat to the heat storage tank 9 for storage through the heat storage tank heating circuit. The specific working process is as follows: start the heating network circulation pump 2, the first circulation pump 4 and the second circulation pump 9. The circulation pump 8 opens the first water supply valve 5, the first return water valve 6, the third water supply valve 15, and the third return water valve 16, and closes the second water supply valve 12 and the second return water valve 13. The municipal heating network return water is heated by the first heat exchanger 3. The water after heat exchange by the first heat exchanger 3 is transported by the first circulation pump 4 to the manifold valve 17 and the second heat exchanger 7 in the heat storage tank circuit. The water after heat exchange by the second heat exchanger 7 is heated by the second circulation pump 8 to the heat storage tank 9. The water at the manifold valve 17 enters the water source heat pump 23. The water source heat pump 23 operates to raise the water temperature to 50~65℃, and then is transported to the user by the user-side circulation pump 24 for heating.

[0033] Mode 3, such as Figure 4 As shown, when the municipal heating network is insufficient to heat the water source heat pump 23, i.e., when the inlet temperature of the water source heat pump 23 is <18℃, while the municipal heating network supply pipe 1 heats the water source heat pump 23 through the municipal heating network heating circuit, the heat storage tank 9 transfers the stored heat to the water source heat pump 23 to supplement the heating supply of the municipal heating pipe; the specific working process is as follows: start the heating network circulation pump 2, the first circulation pump 4, the third circulation pump 10 and the fourth circulation pump 14, open the second water supply valve 12, the second water return valve 13, the third water supply valve 15 and the fourth circulation pump 14. The three return water valves 16 close the first supply water valve 5 and the first return water valve 6; the municipal heating network return water is heated by the first heat exchanger 3, and the water after heat exchange by the first heat exchanger 3 is pushed to the manifold valve 17 by the first circulation pump 4; the hot water in the heat storage tank 9 is heated by the third heat exchanger 11, and the water after heat exchange by the third heat exchanger 11 is pushed to the manifold valve 17 by the fourth circulation pump 14; the water at the manifold valve 17 enters the water source heat pump 23, and the water source heat pump 23 raises the water temperature to 50~65℃, and then provides heating to users through the user-side circulation pump 24.

[0034] Mode 4, such as Figure 5As shown, when the municipal heating network does not supply heat to the water source heat pump 23, i.e., when the municipal return water is interrupted and the top temperature of the heat storage tank 9 is >25℃, the heat storage tank 9 supplies heat to the water source heat pump 23 alone. The specific working process is as follows: shut down the heating network circulation pump 2 and the first circulation pump 4, start the third circulation pump 10 and the fourth circulation pump 14, open the second water supply valve 12 and the second return water valve 13, and close the first water supply valve 5, the first return water valve 6, the third water supply valve 15 and the third return water valve 16; the hot water in the heat storage tank 9 exchanges heat through the third heat exchanger 11, and the water after heat exchange in the third heat exchanger 11 is pushed by the fourth circulation pump 14 to the manifold valve 17, and then enters the water source heat pump 23. The water source heat pump 23 operates to raise the water temperature to 50~65℃, and then supplies heat to users through the user-side circulation pump 24.

[0035] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A municipal heating network low-grade waste heat utilization heating system, comprising a water source heat pump (23) for supplying heat to users, characterized in that, It also includes a heat storage tank (9) and a municipal heating network return water pipe (1). The municipal heating network return water pipe (1) supplies heat to the water source heat pump (23) through the municipal heating network heating circuit. The heat storage tank (9) supplies heat to the water source heat pump (23) through the heat storage tank heating circuit. The heat storage tank (9) is connected to the municipal heating network heating circuit through the heat storage tank heat storage circuit. The heat storage tank (9) regulates the heat storage side temperature of the water source heat pump (23) through the heat storage tank heating circuit and the heat storage tank heat storage circuit.

2. The municipal heating network low-grade waste heat utilization heating system according to claim 1, characterized in that, The heat storage side inlet of the water source heat pump (23) is equipped with a manifold valve (17), and the heat storage tank heating circuit and the water supply pipe in the municipal heating network heating circuit are connected to the manifold valve (17).

3. The municipal heating network low-grade waste heat utilization heating system according to claim 2, characterized in that, The heat storage side outlet of the water source heat pump (23) is equipped with a diversion valve (18), and the heat storage tank heating circuit and the return water pipe in the municipal heating network heating circuit are connected to the diversion valve (18).

4. The municipal heating network low-grade waste heat utilization heating system according to claim 3, characterized in that, The municipal heating network heating circuit includes a first heat exchanger (3) and a first circulating pump (4). The heat absorption side of the first heat exchanger (3) is connected to the municipal heating network return water pipe (1). A heating network circulating pump (2) is installed on the municipal heating network return water pipe (1). The heat release side water supply pipe of the first heat exchanger (3) is connected to the manifold valve (17) through the third water supply valve (15). The first circulating pump (4) is located between the first heat exchanger (3) and the third water supply valve (15). The heat release side return water pipe of the first heat exchanger (3) is connected to the diversion valve (18) through the third return water valve (16).

5. The municipal heating network low-grade waste heat utilization heating system according to claim 3, characterized in that, The heat storage circuit of the heat storage tank includes a second heat exchanger (7) and a second circulation pump (8). The heat absorption side water supply pipe of the second heat exchanger (7) is connected to the outlet of the first circulation pump (4) through the first water supply valve (5). The heat absorption side return water pipe of the second heat exchanger (7) is connected to the heat release side return water pipe of the first heat exchanger (3) through the first return water valve (6). The heat release side water supply pipe and the heat release side return water pipe of the second heat exchanger (7) are both connected to the heat storage tank (9). The second circulation pump (8) is installed on the heat release side water supply pipe of the second heat exchanger (7).

6. The municipal heating network low-grade waste heat utilization heating system according to claim 3, characterized in that, The heat storage tank heating circuit includes a third heat exchanger (11), a third circulation pump (10), and a fourth circulation pump (14). The heat absorption side supply pipe and the heat absorption side return pipe of the third heat exchanger (11) are both connected to the heat storage tank (9). The third circulation pump (10) is installed on the heat absorption side return pipe of the third heat exchanger (11). The heat release side supply pipe of the third heat exchanger (11) is connected to the manifold valve (17) through the second supply valve (12). The heat release side return pipe of the third heat exchanger (11) is connected to the diverter valve (18) through the second return valve (13). The fourth circulation pump (14) is provided between the second return valve (13) and the diverter valve (18).

7. The municipal heating network low-grade waste heat utilization heating system according to any one of claims 1 to 6, characterized in that, The first heat exchanger (3), the second heat exchanger (7) and the third heat exchanger (11) are all plate heat exchangers.

8. The municipal heating network low-grade waste heat utilization heating system according to claim 7, characterized in that, The heat release side outlet of the water source heat pump (23) is connected to the user inlet through the user circulation pump (24), and the user outlet is connected back to the heat release side inlet of the water source heat pump (23).

9. The municipal heating network low-grade waste heat utilization heating system according to claim 8, characterized in that, The water source heat pump (23) includes an evaporator (19), a compressor (20), a condenser (21), and a throttle valve (22) connected in sequence. The manifold valve (17) and the diverter valve (18) are connected to the evaporator (19) respectively, and the user inlet and the user outlet are connected to the condenser (21) respectively.

10. The municipal heating network low-grade waste heat utilization heating system according to claim 9, characterized in that, It also includes a system controller and temperature sensors; the temperature sensors include a first temperature sensor located on the top of the heat storage tank (9), a second temperature sensor located at the inlet of the water source heat pump (23), a third temperature sensor located indoors at the user's location, and a fourth temperature sensor located outdoors at the user's location; the temperature sensors are electrically connected to the system controller to receive temperature signals; the system controller is electrically connected to the heat network circulation pump (2), the first circulation pump (4), the second circulation pump (8), the third circulation pump (10), the fourth circulation pump (14), the water source heat pump (23), and the user circulation pump (24) respectively, and is used to control the operation of the circulation pumps.

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