A distributed heating system

Abstract

The present invention discloses a distributed heating system, which uses a multi-stage countercurrent heat exchange system to utilize the return water heat of a primary pipe network and reduce the return water temperature of the primary pipe network, or utilizes the return water heat of a secondary pipe network, wherein the multi-stage countercurrent heat exchange system comprises N heat exchange units connected by pipelines, each heat exchange unit comprises an evaporator, a condenser, at least one compressor and at least one throttling device, the evaporator, the condenser, the compressor and the throttling device are connected by pipelines to form a refrigerant circulation loop, the evaporator water outlet of the m-1th heat exchange unit is connected to the evaporator water inlet of the m-th heat exchange unit by a pipeline, the condenser water outlet of the m-th heat exchange unit is connected to the condenser water inlet of the m-1th heat exchange unit by a pipeline, wherein m is any integer greater than or equal to 2 and less than or equal to N, and N is an integer greater than or equal to 2.

Description

Technical Field

[0001] The present invention relates to the technical field of heating, and in particular to a distributed heating system. Background Art

[0002] As the size of cities expands, the area of ​​urban centralized heating continues to increase. In the traditional centralized heating system that uses waste heat from power plants as a heat source, the steam extracted from the turbine and the final exhaust steam heat the return water of the primary pipe network. The heated hot water is transported to the heat exchange station through the primary pipe network and heats the return water of the secondary pipe network through the primary heat exchanger. The heated hot water in the secondary pipe network is supplied to heat users. The return water temperature of the primary pipe network is relatively high, for example, about 50°C, so the return water of the primary pipe network still has a certain utilization space. Secondly, the higher return water of the primary pipe network limits the full utilization of the waste heat of the steam turbine of the power plant. The return water of the secondary pipe network also has a certain utilization space. In addition, in the process of developing a heat recovery and utilization system, a device with high thermal efficiency can bring good economic benefits. Summary of the invention

[0003] In order to solve at least one problem of the prior art, the present disclosure provides a distributed heating system.

[0004] According to one aspect of the present disclosure, a distributed heating system includes a multi-stage countercurrent heat exchange system, a primary pipe network and a secondary pipe network, wherein the evaporation side of the multi-stage countercurrent heat exchange system is connected in series to the primary pipe network, and the condensation side of the multi-stage countercurrent heat exchange system is connected in series to the secondary pipe network, and the multi-stage countercurrent heat exchange system absorbs the return water heat of the primary pipe network and heats the return water of the secondary pipe network;

[0005] Among them, the multi-stage countercurrent heat exchange system includes N heat exchange units connected by pipelines, each heat exchange unit includes an evaporator, a condenser, at least one compressor and at least one throttling device, the evaporator, the condenser, the compressor and the throttling device are connected by pipelines to form a refrigerant circulation loop, the evaporator water outlet of the m-1th heat exchange unit is connected to the evaporator water inlet of the m-th heat exchange unit through a pipeline, and the condenser water outlet of the m-1th heat exchange unit is connected to the condenser water inlet of the m-1th heat exchange unit through a pipeline, wherein m is any integer greater than or equal to 2 and less than or equal to N, and N is an integer greater than or equal to 2.

[0006] The beneficial effects of this embodiment are: the multi-stage countercurrent heat exchange system absorbs the heat of the primary pipe network return water and heats the secondary pipe network return water, thereby improving the utilization rate of the primary pipe network heat; reducing the primary pipe network return water temperature, which is conducive to fully utilizing the waste heat of the power plant; the multi-stage countercurrent heat exchange system as a whole has a high thermal efficiency.

[0007] In some embodiments, a primary heat exchanger is further included, and the primary heat exchanger is connected in series with the multi-stage countercurrent heat exchange system. The beneficial effects of this embodiment are: it is applicable to the case where there is a heat exchange station, the multi-stage countercurrent heat exchange system absorbs the heat of the primary pipe network return water, and heats the secondary pipe network return water, thereby improving the utilization rate of the primary pipe network heat; reducing the primary pipe network return water temperature, which is conducive to fully utilizing the waste heat of the power plant.

[0008] In certain embodiments, a flow regulating device is provided upstream of the evaporation side of the multi-stage countercurrent heat exchange system, and the flow regulating device allows the return water of the primary pipe network to enter the evaporation side of the multi-stage countercurrent heat exchange system at a set flow rate.

[0009] In certain embodiments, water flowing out of the evaporation side of the multi-stage countercurrent heat exchange system flows back to the upstream of the evaporation side of the multi-stage countercurrent heat exchange system through a branch pipe. This loop can adjust the inlet water temperature of the evaporation side of the multi-stage countercurrent heat exchange system.

[0010] In some embodiments, the primary pipe network is provided with a flow regulating valve, which is used to regulate the water flow in the primary pipe network.

[0011] According to another aspect of the present disclosure, there is provided a distributed heating system, comprising a multi-stage countercurrent heat exchange system, a primary heat exchanger, a primary pipe network, and a secondary pipe network;

[0012] The return water from the primary pipe network enters the evaporation side of the multi-stage countercurrent heat exchange system;

[0013] The return water from the secondary pipe network is divided into two paths, one of which enters the condensing side of the multi-stage countercurrent heat exchange system, and the other enters the primary heat exchanger. The two return water paths are heated separately and then merged. A water supply temperature control valve is installed at the merging point.

[0014] Among them, the multi-stage countercurrent heat exchange system includes N heat exchange units connected by pipelines, each heat exchange unit includes an evaporator, a condenser, at least one compressor and at least one throttling device, the evaporator, the condenser, the compressor and the throttling device are connected by pipelines to form a refrigerant circulation loop, the evaporator water outlet of the m-1th heat exchange unit is connected to the evaporator water inlet of the m-th heat exchange unit through a pipeline, and the condenser water outlet of the m-1th heat exchange unit is connected to the condenser water inlet of the m-1th heat exchange unit through a pipeline, wherein m is any integer greater than or equal to 2 and less than or equal to N, and N is an integer greater than or equal to 2.

[0015] The beneficial effects of this embodiment are: the multi-stage countercurrent heat exchange system absorbs the return water heat of the primary pipe network and heats the return water of the secondary pipe network, thereby improving the utilization rate of the heat of the primary pipe network; reducing the return water temperature of the primary pipe network, which is conducive to making full use of the waste heat of the power plant; the water supply temperature control valve adjusts the flow distribution between the multi-stage countercurrent heat exchange system and the primary heat exchanger, thereby adjusting the water supply temperature of the secondary heat network.

[0016] In certain embodiments, a flow regulating device is provided upstream of the evaporation side of the multi-stage countercurrent heat exchange system, and the flow regulating device allows the return water of the primary pipe network to enter the evaporation side of the multi-stage countercurrent heat exchange system at a set flow rate.

[0017] In certain embodiments, water flowing out of the evaporation side of the multi-stage countercurrent heat exchange system flows back to the upstream of the evaporation side of the multi-stage countercurrent heat exchange system through a branch pipe. This loop can adjust the inlet water temperature of the evaporation side of the multi-stage countercurrent heat exchange system.

[0018] In some embodiments, the primary pipe network is provided with a flow regulating valve, which is used to regulate the water flow in the primary pipe network.

[0019] According to another aspect of the present disclosure, there is provided a distributed heating system, comprising a multi-stage countercurrent heat exchange system, a primary pipe network, a primary heat exchanger, and a secondary pipe network;

[0020] The evaporation side of the multi-stage countercurrent heat exchange system is connected in series to the secondary pipe network, and the return water of the secondary pipe network flows into the evaporation side of the multi-stage countercurrent heat exchange system. The multi-stage countercurrent heat exchange system absorbs the heat of the return water of the secondary pipe network and heats the water on the condensation side of the multi-stage countercurrent heat exchange system.

[0021] Among them, the multi-stage countercurrent heat exchange system includes N heat exchange units connected by pipelines, each heat exchange unit includes an evaporator, a condenser, at least one compressor and at least one throttling device, the evaporator, the condenser, the compressor and the throttling device are connected by pipelines to form a refrigerant circulation loop, the evaporator water outlet of the m-1th heat exchange unit is connected to the evaporator water inlet of the m-th heat exchange unit through a pipeline, and the condenser water outlet of the m-1th heat exchange unit is connected to the condenser water inlet of the m-1th heat exchange unit through a pipeline, wherein m is any integer greater than or equal to 2 and less than or equal to N, and N is an integer greater than or equal to 2.

[0022] The beneficial effect of this embodiment is that the return water heat of the secondary pipe network 500 is further utilized through the multi-stage countercurrent heat exchange system to supply heat to heat users, and conditions are created for reducing the return water temperature of the primary pipe network. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of a distributed heating system according to Embodiment 1 of the present disclosure.

[0024] Figure 2 Schematic diagram of a heat exchange unit of a multi-stage countercurrent heat exchange system in an embodiment of the present disclosure.

[0025] Figure 3 Schematic diagram of a multi-stage countercurrent heat exchange system in an embodiment of the present disclosure.

[0026] Figure 4 This is a schematic diagram of a distributed heating system according to Embodiment 2 of the present disclosure.

[0027] Figure 5 This is a schematic diagram of a distributed heating system according to Embodiment 3 of the present disclosure.

[0028] Figure 6 This is a schematic diagram of a distributed heating system according to Embodiment 4 of the present disclosure. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0030] Example 1

[0031] Please refer to Figure 1 The distributed heating system includes a multi-stage countercurrent heat exchange system 100, a primary pipe network 300 and a secondary pipe network 500.

[0032] The multi-stage countercurrent heat exchange system 100 includes N heat exchange units 1 connected by pipelines, wherein N is an integer greater than or equal to 2, for example, N is 2, 3, 4 or 5. Figure 2 The heat exchange unit 1 includes an evaporator 11, a condenser 12, at least one compressor 13 and at least one throttling device 14. The evaporator 11, the condenser 12, the compressor 13 and the throttling device 14 are connected by pipelines to form a refrigerant circulation loop. The evaporator 11 can be a shell and tube evaporator or a plate evaporator. The condenser 12 can be a shell and tube condenser or a plate condenser. The evaporator 11 has an evaporator water inlet 111 and an evaporator water outlet 112. The condenser 12 has a condenser water inlet 121 and a condenser water outlet 122.

[0033] The refrigerant circulation loop has a circulating refrigerant, and the refrigerant can be selected from refrigerants known to those skilled in the art, such as R134a refrigerant, which does not damage the ozone layer and has good safety performance. Hot water enters the evaporator 11 from the evaporator water inlet 111 of the evaporator 11, and cooling water enters the condenser 12 from the condenser water inlet 121 of the condenser 12. When the compressor 13 is working, the compressor 13 sucks the low-pressure gaseous refrigerant from the evaporator 11, and the temperature and pressure of the refrigerant are increased after being compressed by the compressor 13, and is sent to the condenser 12. In the condenser 12, the high-temperature and high-pressure gaseous refrigerant transfers heat to the water in the condenser 12 and heats the water, and the gaseous refrigerant condenses into liquid refrigerant. The liquid refrigerant becomes a low-pressure liquid refrigerant after flowing through the throttling device 14, and is sent to the evaporator, wherein the throttling device 14 is a throttle valve. In the evaporator, the low-temperature and low-pressure liquid refrigerant absorbs the heat of the water in the evaporator 11, thereby completing the refrigeration cycle. The heat of the water on the evaporation side is exchanged to the water on the condensation side through the refrigeration cycle.

[0034] In the multi-stage countercurrent heat exchange system 100 provided in this embodiment, the evaporator water outlet 112 of the m-1th heat exchange unit 1 is connected to the evaporator water inlet 111 of the m-1th heat exchange unit 1 through a pipeline, and the condenser water outlet 122 of the m-1th heat exchange unit 1 is connected to the condenser water inlet 121 of the m-1th heat exchange unit 1 through a pipeline, where m is any integer greater than or equal to 2 and less than or equal to N. For a specific description taking N=3 as an example, please refer to Figure 3 , the three heat exchange units 1 are named heat exchange unit 1a, heat exchange unit 1b and heat exchange unit 1c respectively. The heat exchange unit 1a includes an evaporator 11a and a condenser 12a, the evaporator 11a includes an evaporator water inlet 111a and an evaporator water outlet 112a, and the condenser 12a includes a condenser water inlet 121a and a condenser water outlet 122a. The heat exchange unit 1b includes an evaporator 11b and a condenser 12b, the evaporator 11b includes an evaporator water inlet 111b and an evaporator water outlet 112b, and the condenser 12b includes a condenser water inlet 121b and a condenser water outlet 122b. The heat exchange unit 1c includes an evaporator 11c and a condenser 12c, the evaporator 11c includes an evaporator water inlet 111c and an evaporator water outlet 112c, and the condenser 12c includes a condenser water inlet 121c and a condenser water outlet 122c. The evaporator water outlet 112a is connected to the evaporator water inlet 111b through a pipeline, and the evaporator water outlet 112b is connected to the evaporator water inlet 111c through a pipeline. The condenser water outlet 122c is connected to the condenser water inlet 121b through a pipeline, and the condenser water outlet 122b is connected to the condenser water inlet 121a through a pipeline. The spatial layout of the N heat exchange units 1 is not limited to Figure 3 The straight shape shown can also be reasonably arranged according to the space limitations of the use site, for example, it can be arranged in a straight shape, L shape, square shape, etc., but it is not limited to the listed layout forms.

[0035] N evaporators 11 constitute the evaporation side of the multistage countercurrent heat exchange system 100 of the present disclosure, and N condensers 12 constitute the condensation side of the multistage countercurrent heat exchange system 100 of the present disclosure. On the evaporation side of the multistage countercurrent heat exchange system 100, water enters the evaporation side from the evaporator water inlet 111 of the first heat exchange unit 1 of the multistage countercurrent heat exchange system 100, and flows out from the evaporator water outlet 112 of the Nth heat exchange unit 1; on the condensation side of the multistage countercurrent heat exchange system 100, water enters the condensation side from the condenser water inlet 121 of the Nth heat exchange unit 1 of the multistage countercurrent heat exchange system 100, and flows out from the condenser water outlet 122 of the first heat exchange unit 1. Continuing with N=3 as an example, when the multi-stage countercurrent heat exchange system disclosed in the present invention is applied, the water on the evaporation side enters from the evaporator water inlet 111a, is cooled step by step through the evaporator 11a, evaporator 11b and evaporator 11c, and flows out from the evaporator water outlet 112c, while the water on the condensation side enters from the condenser water inlet 121c, is heated step by step through the condenser 12c, condenser 12b and condenser 12a, and flows out from the condenser water outlet 122a. Therefore, the water flow direction on the evaporation side is opposite to that on the condensation side, forming a multi-stage countercurrent heat exchange system. Figure 3 In the embodiment shown, a three-stage heat exchange method is adopted, and each heat exchange unit is configured with a refrigerant circulation system. The inlet and outlet water on the evaporation side have a large temperature difference, and the evaporation side has a lower outlet water temperature.

[0036] Since the multi-stage countercurrent heat exchange system 100 adopts a multi-stage countercurrent method, the water on the evaporation side is cooled down step by step by the 1st, 2nd...N-1, Nth evaporators, while the water on the condensation side is heated up step by step by the Nth, N-1...2nd, 1st condensers. Therefore, each heat exchange unit 1 has a high thermal efficiency, and thus the multi-stage countercurrent heat exchange system 100 as a whole has a high thermal efficiency.

[0037] Please continue to refer to Figure 1 Many heating islands in urban areas are not far from the primary pipe network. Figure 1 The distributed heating system shown directly utilizes the return water heat of the primary pipe network 300. Figure 1 In the illustrated embodiment, the evaporation side of the multi-stage countercurrent heat exchange system 100 is connected in series to the primary pipe network 300 , and the condensation side of the multi-stage countercurrent heat exchange system 100 is connected in series to the secondary pipe network 500 .

[0038] A flow regulating device 600 is provided on the primary pipe network 300. Specifically, the flow regulating device 600 is arranged upstream of the multi-stage countercurrent heat exchange system 100. Usually, the return water temperature of the primary pipe network 300 is about 50°C. Before entering the evaporation side of the multi-stage countercurrent heat exchange system 100, the return water of the primary pipe network 300 is appropriately cooled. Specifically, part of the return water flowing out of the evaporation side of the multi-stage countercurrent heat exchange system 100 flows back to the upstream of the flow regulating device 600 through the branch pipe 900. The return flow of the branch pipe 900 is mixed with the return water of the primary pipe network 300 to adjust the inlet water temperature of the evaporation side of the multi-stage countercurrent heat exchange system 100. A flow regulating valve 700 is also provided on the primary pipe network 300 to adjust the flow of the primary pipe network 300.

[0039] On the primary pipe network side, the return water from the primary pipe network 300 is mixed with the return water from the branch pipe 900, and then passes through the flow control device 600 to enter the evaporation side of the multi-stage countercurrent heat exchange system 100 at the set flow rate and temperature, and flows out after cooling. On the secondary pipe network side, the return water from the secondary heat network 500 enters the condensation side of the multi-stage countercurrent heat exchange system 100, and flows out after heating to be supplied to heat users.

[0040] This embodiment absorbs the return water heat of the primary pipe network 300 through the multi-stage countercurrent heat exchange system 100, and heats the hot water of the secondary pipe network 500, and uses a small amount of compressor electricity to recover a large amount of return water heat of the primary pipe network 300. On the one hand, the return water heat of the primary pipe network 300 can be further utilized; on the other hand, the return water temperature of the primary pipe network 300 can be reduced (for example, the return water temperature of the primary pipe network 300 can be reduced from 50°C to 25°C), which helps to make full use of the waste heat of the power plant turbine.

[0041] Example 2

[0042] Please refer to Figure 4 For the existing heat exchange station, the distributed heating system includes a multi-stage countercurrent heat exchange system 100, a primary pipe network 300, a primary heat exchanger 400 and a secondary pipe network 500. The multi-stage countercurrent heat exchange system 100 refers to the multi-stage countercurrent heat exchange system 100 of Example 1. The multi-stage countercurrent heat exchange system 100 is connected in series with the primary heat exchanger 400 of the heat exchange station, that is, the primary pipe network 300 supplies water into the primary heat exchanger 400, flows into the evaporation side of the multi-stage countercurrent heat exchange system 100 after cooling, and flows out from the evaporation side of the multi-stage countercurrent heat exchange system 100 after cooling again; the return water of the secondary pipe network 500 enters the condensation side of the multi-stage countercurrent heat exchange system 100, flows into the primary heat exchanger 400 after heating, and flows out from the primary heat exchanger 400 after heating again.

[0043] The primary pipe network 300 is provided with a flow regulating device 600, specifically, the flow regulating device 600 is arranged upstream of the multi-stage countercurrent heat exchange system 100. Part of the return water flowing out of the evaporation side of the multi-stage countercurrent heat exchange system 100 flows back to the upstream of the flow regulating device 600 through the branch pipe 900, which is used to adjust the inlet water temperature of the evaporation side of the multi-stage countercurrent heat exchange system 100. The primary pipe network 300 is also provided with a flow regulating valve 700, which is used to adjust the flow of the primary pipe network 300.

[0044] On the primary pipe network side, the supply water of the primary pipe network 300 enters the primary heat exchanger 400, flows out of the primary heat exchanger 400 after cooling, and then mixes with the return flow of the branch pipe 900, and then passes through the flow regulating device 600, so that the return water of the primary pipe network 300 enters the evaporation side of the multi-stage countercurrent heat exchange system 100 at a set flow rate and temperature, and flows out after cooling. On the secondary pipe network side, the return water of the secondary pipe network 500 enters the condensation side of the multi-stage countercurrent heat exchange system 100, enters the primary heat exchanger 400 after heating, and is heated again as the supply water of the secondary pipe network 500 for use by heat users.

[0045] This embodiment absorbs the return water heat of the primary pipe network 300 through the multi-stage countercurrent heat exchange system 100, and heats the hot water of the secondary pipe network 500, and uses a small amount of compressor electricity to recover a large amount of return water heat energy of the primary pipe network 300. On the one hand, the return water heat of the primary pipe network 300 can be further utilized, and on the other hand, the return water temperature of the primary pipe network 300 can be reduced.

[0046] Example 3

[0047] Please refer to Figure 5 As shown, the distributed heating system includes a multi-stage countercurrent heat exchange system 100, a primary pipe network 300, a primary heat exchanger 400 and a secondary pipe network 500. The multi-stage countercurrent heat exchange system 100 refers to the multi-stage countercurrent heat exchange system 100 of Example 1.

[0048] The primary pipe network 300 is provided with a flow regulating device 600, specifically, the flow regulating device 600 is arranged upstream of the multi-stage countercurrent heat exchange system 100. Part of the return water flowing out of the evaporation side of the multi-stage countercurrent heat exchange system 100 flows back to the upstream of the flow regulating device 600 through the branch pipe 900, which is used to adjust the inlet water temperature of the evaporation side of the multi-stage countercurrent heat exchange system 100. The primary pipe network 300 is also provided with a flow regulating valve 700, which is used to adjust the flow of the primary pipe network 300.

[0049] The condensation side of the multi-stage countercurrent heat exchange system 100 and the primary heat exchanger 400 are heated in parallel. On the primary pipe network side, the water supply of the primary pipe network 300 enters the primary heat exchanger 400, flows out after cooling, and then mixes with the return flow of the branch pipe 900, and then passes through the flow regulating device 600, so that the return water of the primary pipe network 300 enters the evaporation side of the multi-stage countercurrent heat exchange system 100 at a set flow rate and temperature, and flows out of the evaporation side after cooling again. On the secondary pipe network side, the return water of the secondary pipe network 500 is divided into two paths, one of which enters the primary heat exchanger 400, and the other enters the condensation side of the multi-stage countercurrent heat exchange system 100, and then the two hot waters are heated and merged, and a water supply temperature control valve 800 is provided at the confluence.

[0050] In this embodiment, the return water heat of the primary pipe network 300 is absorbed by the multi-stage countercurrent heat exchange system 100, and the hot water of the secondary pipe network 500 is heated, so the return water heat of the primary pipe network 300 is utilized and the return water temperature of the primary pipe network 300 is reduced. The water supply temperature control valve 800 distributes the flow of the multi-stage countercurrent heat exchange system 100 and the primary heat exchanger 400, and adjusts the water supply temperature of the secondary pipe network 500.

[0051] Example 4

[0052] Please refer to Figure 6 This embodiment provides a distributed heating system, which includes a multi-stage countercurrent heat exchange system 100, a primary pipe network 300, a primary heat exchanger 400 and a secondary pipe network 500. The multi-stage countercurrent heat exchange system 100 refers to the multi-stage countercurrent heat exchange system 100 of Embodiment 1.

[0053] The evaporation side of the multi-stage countercurrent heat exchange system 100 is connected in series to the secondary pipe network 500. On the primary pipe network side, the water supplied by the primary pipe network 300 enters the primary heat exchanger 400 and flows out of the primary heat exchanger 400 after cooling. On the secondary pipe network side, the return water of the secondary pipe network 500 enters the evaporation side of the multi-stage countercurrent heat exchange system 100, enters the primary heat exchanger 400 after cooling, and flows out of the primary heat exchanger 400 after heating.

[0054] The high-temperature water supply of the primary pipe network 300 heats the secondary pipe network 500 through the primary heat exchanger 400, and the heated hot water of the secondary pipe network 500 is supplied to heat users. The return water temperature of the secondary pipe network 500 is usually 40-45°C. In this embodiment, the multi-stage countercurrent heat exchange system 100 is used to absorb the heat of the return water of the secondary pipe network 500 again, and the refrigeration cycle is used to absorb the heat of the return water of the secondary pipe network 500 and heat the hot water on the condensation side of the multi-stage countercurrent heat exchange system 100. The hot water flowing out of the condensation side of the multi-stage countercurrent heat exchange system 100 can be supplied to other heat users. In this embodiment, the return water heat of the secondary pipe network 500 is further utilized by the multi-stage countercurrent heat exchange system 100. Since the return water temperature of the secondary pipe network 500 is reduced, conditions are created for the reduction of the return water temperature of the primary pipe network 300.

[0055] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A distributed heating system, characterized in that: It includes a multi-stage countercurrent heat exchange system, a primary heat exchanger, a primary pipe network and a secondary pipe network; The return water from the primary pipe network enters the evaporation side of the multi-stage countercurrent heat exchange system; The return water from the secondary pipe network is divided into two paths, one of which enters the condensing side of the multi-stage countercurrent heat exchange system, and the other enters the primary heat exchanger. The two return water paths are heated separately and then merged. A water supply temperature control valve is installed at the merging point. Wherein, the multi-stage countercurrent heat exchange system comprises N heat exchange units connected by pipelines, each heat exchange unit comprises an evaporator, a condenser, at least one compressor and at least one throttling device, the evaporator, the condenser, the compressor and the throttling device are connected by pipelines to form a refrigerant circulation loop, the evaporator water outlet of the m-1 heat exchange unit is connected to the evaporator water inlet of the m-1 heat exchange unit through a pipeline, and the condenser water outlet of the m-1 heat exchange unit is connected to the condenser water inlet of the m-1 heat exchange unit through a pipeline, wherein m is any integer greater than or equal to 2 and less than or equal to N, and N is an integer greater than or equal to 2; The water flowing out from the evaporation side of the multi-stage countercurrent heat exchange system flows back to the upstream of the evaporation side of the multi-stage countercurrent heat exchange system through a branch pipe, and the primary pipe network is provided with a flow regulating valve.

2. The distributed heating system according to claim 1, characterized in that: A flow regulating device is provided upstream of the evaporation side of the multi-stage countercurrent heat exchange system to adjust the temperature of water entering the evaporation side.

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