Heat supply system based on water supply-supply mixing device

Abstract

The invention discloses a heat supply system based on a supply-supply water mixing device, which relates to the field of central heat supply and comprises a heat exchanger, a make-up pump, a circulating pump, a water mixing unit and a heat utilization unit, the water mixing unit comprises a secondary network mixing water pump and a tertiary network mixing water pump; the pipeline between the heat exchanger and the water mixing unit is a secondary pipe network, and the pipeline between the water mixing unit and the heat utilization unit is a tertiary pipe network; an outlet of the heat exchanger 1 is connected with an inlet of a secondary pipe network of the water mixing unit, and an outlet of a tertiary pipe network of the water mixing unit is connected to an inlet of the heat utilization unit; an outlet of the heat utilization unit is connected with an inlet of a tertiary pipe network of the water mixing unit, and an outlet of a secondary pipe network of the water mixing unit is connected with an inlet of the circulating pump. By means of intelligent cooperative management of the control system on starting, stopping and operation parameters of the water pump, safe, stable, efficient and intelligent control of the heat supply system under multi-mode operation is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of central heating, in particular to a heating system based on a supply-supply water mixing device. BACKGROUND

[0002] In the field of central heating, water mixing heating technology is widely used in urban area heating by mixing high-temperature hot water in the primary network with low-temperature return water in the secondary or tertiary network to adjust the water supply temperature to meet different heating load requirements. To improve operational flexibility, some systems are designed to switch between intermittent heating and water mixing heating modes, especially suitable for complex climate conditions such as high-cold regions. The system usually configures components such as heat exchangers, circulating pumps, and water mixing pumps to realize the conversion of heat transfer modes by controlling the start and stop of different water pumps, while ensuring heating quality and optimizing energy efficiency.

[0003] In existing systems with switchable modes, when switching from intermittent heating to water mixing heating, the system pressure distribution changes due to changes in water pump operating state and water flow path. To ensure that the high point of the system is not empty and the low point is not over-pressurized after switching, the set pressure value of the water supply pump usually needs to be reset, increasing the complexity of control and the need for manual intervention, which is not conducive to the automatic operation and rapid response of the system. Especially in winter, frequent load fluctuations require frequent adjustment of the set pressure value, which affects system stability. SUMMARY

[0004] In view of the above existing problems, the present application is proposed.

[0005] Therefore, the present application provides a heating system based on a supply-supply water mixing device to solve the problem of existing systems that require adjustment of the water supply set pressure value during mode switching, resulting in complex control and poor stability.

[0006] To solve the above technical problems, the present application provides the following technical solutions: The present application provides a heating system based on a supply-supply water mixing device, which includes a heat exchanger, a water supply pump, a circulating pump, a water mixing unit, and a heat utilization unit. The water mixing unit includes a secondary network water mixing pump and a tertiary network water mixing pump. The pipeline between the heat exchanger and the water mixing unit is the secondary pipe network, and the pipeline between the water mixing unit and the heat utilization unit is the tertiary pipe network. The outlet of the heat exchanger is connected to the inlet of the secondary pipe network of the water mixing unit, and the outlet of the tertiary pipe network of the water mixing unit is connected to the inlet of the heat utilization unit. The outlet of the heat utilization unit is connected to the inlet of the tertiary pipe network of the water mixing unit, and the outlet of the secondary pipe network of the water mixing unit is connected to the inlet of the circulating pump. The outlet of the circulating pump is connected to the inlet of the heat exchanger. The water supplement pipe of the water supplement pump is connected to the inlet of the circulating pump.

[0007] As a preferred scheme of the heat supply system based on the supply-supply water mixing device, the secondary network water mixing pump is arranged on the water supply pipeline of the secondary pipe network, and is used for pressurizing the high-temperature primary network hot water from the outlet of the heat exchanger and sending the high-temperature primary network hot water into the water mixing unit for mixing; and the tertiary network water mixing pump is arranged on the water supply pipeline of the tertiary pipe network, and is used for pressurizing the mixed warm water and sending the mixed warm water to the heat utilization unit.

[0008] As a preferred scheme of the heat supply system based on the supply-supply water mixing device, when the system is in the intermittent-continuous heat supply operation mode, the secondary network water mixing pump and the tertiary network water mixing pump are closed, and the circulating pump is opened; the high-temperature primary network hot water sequentially flows through the heat exchanger, the secondary pipe network, the tertiary pipe network and the heat utilization unit, is returned to the inlet of the water mixing unit after heat release through the tertiary network return water pipe, and is returned to the inlet of the circulating pump through the secondary network return water pipe. The actual head of the circulating pump The expression is satisfied: ; Among them, is the pressure drop caused by the flow resistance inside the heat exchanger, is the total pressure drop of the pipe network of the secondary pipe network and the tertiary pipe network, is the pipe pressure drop of the tertiary pipe network return water section, is the pipe pressure drop of the secondary network return water section.

[0009] As a preferred scheme of the heat supply system based on the supply-supply water mixing device, in the intermittent-continuous heat supply operation mode, the pressure at the water supplement pump access point is P , and the pressure at the inlet of the heat utilization unit is The expression is: = P + H −Δ P −Δ P ; The pressure value needs to ensure that the highest point of the system is not empty and the end is not overpressure, and the constant water supplement pressure P2 maintained by the water supplement pump realizes the constant pressure of the system.

[0010] As a preferred scheme of the heat supply system based on the supply-supply water mixing device, when the system is switched to the secondary-supply-tertiary-supply water mixing heat supply operation mode, the circulating pump is closed, and the secondary network water mixing pump and the tertiary network water mixing pump are opened; The high-temperature primary network hot water is heated by the heat exchanger, enters the secondary pipe network water supply pipe, is pressurized by the secondary network water mixing pump, and is sent into the water mixing unit; Low-temperature return water from the heat-using unit enters the mixing unit through the tertiary pipeline return water pipe, where it is mixed with high-temperature supply water to cool down and form hot water at a suitable temperature. The mixed hot water is pressurized by the tertiary network mixing pump and then transported to the heat-using unit through the tertiary network water supply pipe; The actual head of the secondary network mixing pump is The actual head of the tertiary network mixing pump is .

[0011] As a preferred embodiment of the heating system based on a supply-supply mixing device described in this invention, in the two-supply-three-supply mixing heating operation mode, the system satisfies the energy conservation condition, that is, the total head provided by the secondary network mixing pump and the tertiary network mixing pump is approximately equal to the head required by the original circulating pump, expressed as: ; Assuming the pipeline layout, equipment configuration, and flow rate remain essentially unchanged, the pressure drop in each section... ~ Keep relatively constant. Established.

[0012] As a preferred embodiment of the heating system based on a supply-supply mixing device described in this invention, wherein: in the two-supply-three-supply mixing heating operation mode, the pressure at the inlet of the heat-using unit is... The expression is: ; Associativity Substituting into the above equation, we get: If the pressure at the water replenishment point is maintained If it remains unchanged, then use the inlet pressure of the thermal unit. Basically constant.

[0013] As a preferred embodiment of the heating system based on the supply-supply mixing device described in this invention, the constant pressure setting value of the water supply pump remains unchanged when switching between the intermittent heating operation mode and the two-supply-three-supply mixing water heating operation mode.

[0014] As a preferred embodiment of the heating system based on the supply-supply mixing device described in this invention, the mixing unit adopts an integrated design with a built-in mixing chamber to ensure that the high-temperature secondary network supply water and the low-temperature tertiary network return water are fully mixed, and the outlet water temperature is uniform and controllable.

[0015] As a preferred embodiment of the heating system based on the supply-supply mixing device described in this invention, it further includes a control system, which is electrically connected to the secondary network mixing pump, the tertiary network mixing pump, and the circulating pump. The control system automatically starts and stops the corresponding pumps according to the heating mode command, monitors the system pressure and temperature parameters, and performs intelligent switching of the heating mode and safe operation.

[0016] The application has the advantages that: by setting the secondary network water mixing pump at the secondary pipe network water supply side and the tertiary network water mixing pump at the tertiary pipe network water supply side, a two-supply-three-supply water mixing structure is formed, the pressure characteristics of the user end in different heating modes are highly consistent, the pressure fluctuation caused by the switching of the water pump operation state is avoided, so that the system high point is not empty and the low point is not over-pressured without adjusting the water supply pressure value, and the automation degree and operation stability of mode switching are improved; further combining the time-sharing start-stop control of the circulating pump and the water mixing pump and the energy head matching design, smooth conversion between the intermittent heating and the water mixing heating modes is realized, not only the operation process is simplified, but also the adaptability of the system to load changes is enhanced, the integrated water mixing unit ensures the mixing uniformity and temperature controllability, and through the intelligent collaborative management of the control system to the water pump start-stop and operation parameters, the safety, stability, efficiency and intelligent control of the heating system in multiple modes are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creating labor.

[0018] Fig. 1 It is a schematic diagram of the system that can switch between intermittent supply and water mixing.

[0019] Fig. 2 It is a two-return-three-supply water mixing system diagram.

[0020] Fig. 3 It is a two-supply-three-supply water mixing system diagram.

[0021] In the figure, 1 is a heat exchanger, 2 is a water supply pump, 3 is a circulating pump, 4 is a secondary network water mixing pump, 5 is a tertiary network water mixing pump, and 6 is a heat using unit. DETAILED DESCRIPTION

[0022] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the drawings.

[0023] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0024] Second, the "one embodiment" or "an embodiment" referred to herein can include a particular feature, structure, or characteristic. The various embodiments are not mutually exclusive, but a single embodiment can be selected from a plurality of mutually exclusive or alternative embodiments.

[0025] Referring to Figs. 1-3 For one embodiment of the present application, the embodiment provides a heat supply system based on a supply-supply water mixing device, comprising the following steps: The secondary network water mixing pump 4 is arranged on the water supply pipeline of the secondary pipe network, and is used for pressurizing the high-temperature primary network hot water from the outlet of the heat exchanger 1 and sending the high-temperature primary network hot water into the water mixing unit for mixing. The tertiary network water mixing pump 5 is arranged on the water supply pipeline of the tertiary pipe network, and is used for pressurizing and delivering the mixed warm water to the heat using unit 6.

[0026] Further, the secondary network water mixing pump 4 is installed on the water supply pipeline of the secondary pipe network between the outlet of the heat exchanger 1 and the water mixing unit, and is used for pressurizing the high-temperature primary network hot water from the outlet of the heat exchanger 1, so that the high-temperature primary network hot water has enough dynamic pressure head to enter the water mixing unit. Inside the water mixing unit, the pressurized high-temperature primary network hot water is mixed with the low-temperature return water from the outlet of the heat using unit 6 and returned through the tertiary pipe network return water pipe, to form a heat supply medium with a suitable temperature. The tertiary network water mixing pump 5 is installed on the water supply pipeline of the tertiary pipe network between the outlet of the water mixing unit and the inlet of the heat using unit 6, and is used for pressurizing the mixed warm water again, so that the mixed warm water can overcome the flow resistance of the tertiary pipe network water supply section and the heat using unit 6 itself, and be stably delivered to the inlet of the heat using unit 6 to meet the heat supply demand of the remote user.

[0027] When the system is in the intermittent-continuous heat supply operation mode, the secondary network water mixing pump 4 and the tertiary network water mixing pump 5 are closed, and the circulating pump 3 is opened. The high-temperature primary network hot water flows through the heat exchanger 1, the secondary pipe network, the tertiary pipe network, and the heat using unit 6 in sequence, and is returned to the inlet of the water mixing unit after heat release, and then is returned to the inlet of the circulating pump 3 through the secondary pipe network return water pipe.

[0028] The actual head of the circulating pump 3 satisfies the expression.

[0029] ; wherein, is the pressure drop caused by the flow resistance inside the heat exchanger 1, is the total pressure drop of the pipe sections of the secondary pipe network and the tertiary pipe network water supply section, is the pipe pressure drop of the tertiary pipe network return water section, is the pipe pressure drop of the secondary pipe network return water section.

[0030] Furthermore, in the intermittent heating operation mode, the secondary network mixing pump 4 and the tertiary network mixing pump 5 are in the off state, while the circulating pump 3 is in the on state; high-temperature primary network hot water flows out from the outlet of heat exchanger 1, flows through the secondary network and tertiary network in sequence, and enters the heat-using unit 6 to release heat; the low-temperature return water after heat release flows out from the outlet of heat-using unit 6, enters the tertiary network inlet of the mixing unit through the tertiary network return water pipe, and then returns to the inlet of the circulating pump 3 through the secondary network return water pipe; the circulating pump 3 pressurizes the return water, causing it to re-enter the heat exchanger 1 to complete the closed-loop circulation; the actual head required by the circulating pump 3 is... This is equal to the sum of the pressure drop caused by the internal flow resistance of heat exchanger 1, the total pressure drop of the secondary and tertiary water supply sections, the pressure drop of the tertiary water return section, and the pressure drop of the secondary water return section. .

[0031] In the indirect heating operation mode, the pressure at the connection point of the water supply pump 2 is set as follows: P 2. Then use the pressure at the inlet of heating unit 6. The expression is: = P 2+ H 3−Δ P 1−Δ P 2; The pressure value must ensure that the system does not run dry at its highest point and that there is no overpressure at the end, and the water supply pump 2 maintains a constant water supply pressure. P 2. Achieve constant system pressure.

[0032] Furthermore, in the intermittent heating operation mode, the pressure at the connection point of the make-up water pump 2 is... The actual head of circulating pump 3 is The flow resistance inside heat exchanger 1 causes a pressure drop Δ P 1. The total pressure drop of the secondary and tertiary water supply sections is: Pressure at the inlet of heating unit 6 equal to the pressure at the connection point of water pump 2 In addition to the actual head provided by circulating pump 3 Subtract the pressure drop Δ of heat exchanger 1 P 1. The total pressure drop of the water supply pipeline, i.e. = P 2+ H 3−Δ P 1−Δ P 2; This pressure value must ensure that no emptying occurs at the highest point of the heating network where heat unit 6 is located during operation, and that no overpressure leakage occurs at the lowest point. The pressure at the connection point is maintained by the water supply pump 2. Constant pressure is achieved, enabling static pressure control across the entire network.

[0033] When the system switches to the secondary-tertiary mixed water heating operation mode, the circulating pump 3 is turned off, and the secondary network mixed water pump 4 and the tertiary network mixed water pump 5 are turned on.

[0034] Furthermore, when switching from the intermittent heating operation mode to the secondary-tertiary mixed water heating operation mode, the circulating pump 3 is in the off state, while the secondary network mixing pump 4 and the tertiary network mixing pump 5 are in the on state. After being heated by heat exchanger 1, the hot water from the primary network enters the secondary network water supply pipe, and is then pressurized by the secondary network mixing pump 4 before being sent to the mixing unit.

[0035] Furthermore, after being heated by heat exchanger 1, the high-temperature primary network hot water flows out from the outlet of heat exchanger 1 and enters the secondary network water supply pipe. It then flows through the secondary network water supply pipe to the inlet of the secondary network mixing pump 4, where the secondary network mixing pump 4 pressurizes the high-temperature primary network hot water to give it sufficient dynamic head to enter the mixing unit.

[0036] Low-temperature return water from heat-using unit 6 enters the mixing unit through the tertiary pipeline return water pipe. In the mixing unit, it mixes with high-temperature supply water to cool down and form hot water at a suitable temperature.

[0037] Furthermore, the low-temperature return water from the outlet of the heat-using unit 6 is transported to the inlet of the tertiary network of the mixing unit via the tertiary network return water pipe. Inside the mixing unit, the high-temperature primary network hot water, pressurized by the secondary network mixing pump 4, is mixed with the low-temperature return water to form a mixed hot water with a suitable temperature.

[0038] The mixed hot water is pressurized by the tertiary network mixing pump 5 and then transported to the heating unit 6 through the tertiary network water supply pipe.

[0039] Furthermore, the mixed hot water flows out from the outlet of the tertiary network of the mixing unit, enters the tertiary network water supply pipe, flows through the tertiary network mixing pump 5, pressurizes the mixed hot water to increase its energy level, and then delivers it to the inlet of the heat-using unit 6 through the tertiary network water supply pipe to complete the heat supply process.

[0040] The actual head of the secondary network mixing pump 4 is The actual head of the tertiary mixing pump 5 is .

[0041] Furthermore, the secondary network mixing pump 4 provides actual head during operation. The tertiary mixing pump 5 provides the actual head during operation. Both of them jointly undertake the energy transfer task originally performed by circulating pump 3.

[0042] Under the secondary-tertiary mixed water heating operation mode, the system meets the energy conservation condition, that is, the total head provided by the secondary network mixing pump 4 and the tertiary network mixing pump 5 is approximately equal to the head required by the original circulating pump 3, as expressed in the following expression: ; Assuming the pipeline layout, equipment configuration, and flow rate remain essentially unchanged, the pressure drop in each section... ~ Keep relatively constant. Established.

[0043] Furthermore, in the secondary-tertiary mixed water heating operation mode, the actual head provided by the secondary network mixing pump 4 is H4, and the actual head provided by the tertiary network mixing pump 5 is... The total head provided by the two together Used to overcome the pressure drop caused by the internal flow resistance of heat exchanger 1 Total pressure drop in the secondary and tertiary water supply sections Pipeline pressure drop in the return water section of the tertiary pipeline network and the pressure drop in the secondary network return water section Under the condition that the pipeline layout, equipment configuration and design flow remain basically unchanged, the pressure drop of the above sections is... to To maintain relative stability, the total head provided by the secondary network mixing pump 4 and the tertiary network mixing pump 5 together... + Approximately equal to the actual head required by circulating pump 3 under indirect heating operation mode. ,Right now .

[0044] Under the mixed water heating operation mode of secondary and tertiary supply, the pressure at the inlet of heating unit 6 The expression is: ; Associativity Substituting into the above equation, we get: If the pressure at the water replenishment point is maintained If it remains unchanged, then use the inlet pressure of the thermal unit. Basically constant.

[0045] Furthermore, in the mixed water heating operation mode of secondary and tertiary supply, the pressure at the inlet of heating unit 6... equal to the pressure at the connection point of water pump 2 Subtract the pressure drop of heat exchanger 1 In addition to the actual head H4 of the secondary network mixing pump 4 and the actual head of the tertiary network mixing pump 5 Subtract the total pressure drop of the secondary and tertiary water supply sections. ,Right now ;because Substituting into the pressure expression, we get This expression relates to the inlet pressure of heat unit 6 under the indirect heating operation mode. The calculation expression is consistent, therefore, when switching between the two operating modes, if the pressure at the connection point of the water supply pump 2 is maintained... If it remains unchanged, then use the pressure at the inlet of heat unit 6. It remains basically constant.

[0046] When switching between the intermittent heating operation mode and the mixed water heating operation mode of the secondary and tertiary supply, the constant pressure setting value of the water supply pump 2 remains unchanged.

[0047] Furthermore, when switching between the intermittent heating operation mode and the mixed water heating operation mode of the secondary and tertiary supply systems, the set pressure of the makeup water pump 2 remains unchanged, without the need to be reset according to the change of operation mode. The mixing unit adopts an integrated design with a built-in mixing chamber to ensure that the high-temperature secondary network water supply and the low-temperature tertiary network return water are fully mixed, and the outlet water temperature is uniform and controllable.

[0048] Furthermore, the mixing unit adopts an integrated structure with a mixing chamber inside. High-temperature primary network hot water is pressurized by the secondary network mixing pump 4 and enters the mixing chamber from the secondary network side. Low-temperature return water enters the mixing chamber from the heat-using unit 6 through the tertiary network return pipe. The two water flows are fully mixed in the mixing chamber. The reasonable flow guiding structure promotes heat and mass exchange, ensuring that the temperature distribution of the mixed hot water at the outlet is uniform and the fluctuation is small, thus meeting the subsequent heating demand.

[0049] It also includes a control system, which is electrically connected to the secondary network mixing pump 4, the tertiary network mixing pump 5 and the circulating pump 3. The control system automatically starts and stops the corresponding pumps according to the heating mode command, and monitors the system pressure and temperature parameters to perform intelligent switching of heating modes and safe operation.

[0050] Furthermore, the control system connects the secondary network mixing pump 4, the tertiary network mixing pump 5, and the circulating pump 3 via electrical lines. It receives external heating mode commands and automatically executes the start and stop operations of the corresponding pumps according to the commands. When switching to the intermittent heating operation mode, the control system sends a signal to shut down the secondary network mixing pump 4 and the tertiary network mixing pump 5, while simultaneously starting the circulating pump 3. When switching to the two-supply-three-supply mixed water heating operation mode, the control system sends a signal to shut down the circulating pump 3, while simultaneously starting the secondary network mixing pump 4 and the tertiary network mixing pump 5. The control system continuously collects pressure data at the connection point of the makeup water pump 2, temperature data at the inlet and outlet of the heating unit 6, and pressure and temperature parameters of other key nodes, monitors the operating status in real time, verifies whether the pressure is stable and whether the temperature reaches the set range during the pump switching process, and triggers a safety response when abnormal operating conditions are detected, thereby realizing automatic switching between different heating modes and ensuring operational safety.

[0051] In summary, this invention, by placing the secondary network mixing pump on the secondary network supply side and the tertiary network mixing pump on the tertiary network supply side, forms a two-supply-three-supply mixing structure. This achieves a high degree of consistency in user-end pressure characteristics under different heating modes, avoiding pressure fluctuations caused by pump operation state switching. Therefore, it ensures that the system does not run dry at high points or overpressure at low points without adjusting the makeup water pressure setting value, improving the automation level and operational stability of mode switching. Furthermore, by combining the time-sharing start-stop control and energy head matching design of the circulating pump and mixing pump, a smooth transition between indirect heating and mixing heating modes is achieved. This not only simplifies the operation process but also enhances the system's adaptability to load changes. Combined with the integrated mixing unit, it ensures mixing uniformity and temperature controllability. Finally, through the intelligent collaborative management of pump start-stop and operating parameters by the control system, it achieves safe, stable, efficient, and intelligent control of the heating system under multi-mode operation.

[0052] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A heating system based on a supply-supply mixing device, characterized in that: include: Heat exchanger (1), water supply pump (2), circulating pump (3), mixing unit and heat-using unit (6); The mixing unit includes a secondary network mixing pump (4) and a tertiary network mixing pump (5). The pipeline between the heat exchanger (1) and the mixing unit is a secondary pipeline network, and the pipeline between the mixing unit and the heat-using unit (6) is a tertiary pipeline network. The outlet of the heat exchanger 1 is connected to the inlet of the secondary pipe network of the mixing unit, and the outlet of the tertiary pipe network of the mixing unit is connected to the inlet of the heat-using unit (6). The outlet of the heat-using unit (6) is connected to the inlet of the tertiary pipeline of the mixing unit, and the outlet of the secondary pipeline of the mixing unit is connected to the inlet of the circulating pump (3). The outlet of the circulating pump (3) is connected to the inlet of the heat exchanger (1); The water supply pipe of the water supply pump (2) is connected to the inlet of the circulating pump (3).

2. The heating system based on a supply-supply mixing device as described in claim 1, characterized in that: The secondary network mixing pump (4) is installed on the water supply pipeline of the secondary network and is used to pressurize the high-temperature primary network hot water from the outlet of the heat exchanger (1) and send it to the mixing unit for mixing. The tertiary network mixing pump (5) is installed on the water supply pipeline of the tertiary network and is used to pressurize and transport the mixed warm water to the heat-using unit (6).

3. The heating system based on a supply-supply mixing device as described in claim 2, characterized in that: When the system is in the intermittent heating operation mode, the secondary network mixing pump (4) and the tertiary network mixing pump (5) are turned off, and the circulation pump (3) is turned on. The high-temperature primary network hot water flows through the heat exchanger (1), the secondary network, and the tertiary network to the heat-using unit (6) in sequence. After releasing heat, it returns to the mixing unit inlet through the tertiary network return water pipe, and then returns to the circulation pump (3) inlet through the secondary network return water pipe. Actual head of circulating pump (3) Satisfying the expression: ； in, The pressure drop is caused by the flow resistance inside the heat exchanger (1). The total pressure drop of the secondary and tertiary water supply networks. The pressure drop in the return water section of the tertiary pipeline network. Pressure drop in the secondary network return water section.

4. The heating system based on a supply-supply mixing device as described in claim 3, characterized in that: In the indirect heating operation mode, the pressure at the connection point of the water supply pump (2) is set as follows: P 2. The pressure at the inlet of the heat unit (6) is then used. The expression is: = P 2+ H 3−D P 1−D P 2; The pressure value must ensure that the system does not run dry at its highest point and that there is no overpressure at the end. The constant water supply pressure is maintained by the water supply pump (2). P 2. Achieve constant system pressure.

5. The heating system based on a supply-supply mixing device as described in claim 2, characterized in that: When the system switches to the secondary-tertiary mixed water heating operation mode, the circulating pump (3) is turned off and the secondary network mixed water pump (4) and the tertiary network mixed water pump (5) are turned on. After being heated by the heat exchanger (1), the hot water from the high-temperature primary network enters the secondary network water supply pipe and is pressurized by the secondary network mixing pump (4) before being sent to the mixing unit. Low-temperature return water from the heat-using unit (6) enters the mixing unit through the tertiary pipeline return water pipe, where it is mixed with high-temperature supply water to cool down and form hot water at a suitable temperature. The mixed hot water is pressurized by the tertiary network mixing pump (5) and then transported to the heat-using unit (6) through the tertiary network water supply pipe; The actual head of the secondary network mixing pump (4) is The actual head of the tertiary mixing pump (5) is .

6. The heating system based on a supply-supply mixing device as described in claim 5, characterized in that: Under the two-supply-three-supply mixed water heating operation mode, the system meets the energy conservation condition, that is, the total head provided by the secondary network mixed water pump (4) and the tertiary network mixed water pump (5) is approximately equal to the head required by the original circulating pump (3), as expressed in the following expression: ； Assuming the pipeline layout, equipment configuration, and flow rate remain essentially unchanged, the pressure drop in each section... ~ Keep relatively constant. Established.

7. The heating system based on a supply-supply mixing device as described in claim 6, characterized in that: In the two-supply-three-supply mixed water heating operation mode, the pressure at the inlet of the heat-using unit (6) The expression is: ； Associativity Substituting into the above equation, we get: If the pressure at the water replenishment point is maintained If it remains unchanged, then use the inlet pressure of the thermal unit. Basically constant.

8. The heating system based on a supply-supply mixing device as described in claim 7, characterized in that: When switching between the intermittent heating operation mode and the mixed water heating operation mode of the two-supply and three-supply systems, the constant pressure setting value of the water supply pump (2) remains unchanged.

9. A heating system based on a supply-supply mixing device according to any one of claims 1 to 8, characterized in that: The mixing unit adopts an integrated design with a built-in mixing chamber to ensure that the high-temperature secondary network water supply and the low-temperature tertiary network return water are fully mixed, and the outlet water temperature is uniform and controllable.

10. A heating system based on a supply-supply mixing device according to any one of claims 1 to 9, characterized in that: It also includes a control system, which is electrically connected to the secondary network mixing pump (4), the tertiary network mixing pump (5) and the circulating pump (3). The control system automatically starts and stops the corresponding pumps according to the heating mode command, and monitors the system pressure and temperature parameters to perform intelligent switching and safe operation of the heating mode.

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