A heat supply unit and method for reducing return water temperature

Abstract

The application discloses a kind of reduce return water temperature heating unit and reduce return water temperature method, it is related to heating ventilation air conditioning technical field, this reduce return water temperature heating unit mainly includes unit controller, room temperature sensor, heat exchanger, electric regulating valve, electric on-off valve and secondary network circulating pump;When operation data indicates that secondary network circulating pump is operated in 100% design flow condition and electric on-off valve is in on condition, the parameter of secondary network water supply temperature regulator is set, and according to the parameter of secondary network water supply temperature regulator, the valve position action of electric regulating valve is controlled, so that the deviation of actual value and target value of secondary network water supply temperature is within the set range;Simultaneously according to operation data and electric on-off valve on-off mode, regulate and control secondary network return water temperature, and then regulate and control primary network return water temperature.The application can realize the effect of low return water temperature at low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the HVAC (Heating, Ventilation and Air Conditioning) technical field, in particular to a heating unit for reducing return water temperature and a method for reducing return water temperature. BACKGROUND

[0002] The lower the return water temperature of the primary network is, the higher the heat network delivery efficiency is; if the heat source is from cogeneration, more waste heat can be utilized to increase the power generation efficiency of the cogeneration heat source; if the heat source is a gas boiler, flue gas waste heat can be recovered to improve the boiler efficiency, so the low return water temperature is very important for the heating unit and the heat source.

[0003] However, in practice, it is very difficult to reduce the return water temperature of the heating unit, and the currently available methods are as follows:

[0004] (1) The method of using an absorption heat pump to reduce the return water temperature of the primary network, in which the absorption heat pump is expensive, occupies a large area, and is difficult to operate and maintain, so it is difficult to be widely promoted.

[0005] (2) The method of using an electric heat pump to reduce the return water temperature of the primary network, in which the electric heat pump needs to use electricity, and the cost of the electric heat pump is also high, and it is a complex device with high operation and maintenance difficulty.

[0006] (3) The method of increasing the area of the heat user radiator to reduce the return water temperature of the primary network, in which the radiator has been installed in the heat user's home, and it is difficult to increase the heat dissipation area, and the pipeline has been arranged, so it is difficult to replace, and therefore this method is not feasible in practice.

[0007] (4) The method of reducing the flow of the secondary network to reduce the return water temperature of the secondary network, and then reducing the return water temperature of the primary network, in which reducing the flow of the secondary network will cause hydraulic imbalance, so this method is difficult to use in practice.

[0008] (5) The method of using a cascade heat exchange mode to reduce the return water temperature of the primary network, in which the primary outlet water of the terminal heat exchanger for heating is used as the primary inlet water of the terminal heat exchanger for floor heating, so that the return water temperature of the primary network is close to the return water temperature of the floor heating system, and the return water temperature of the primary network is reduced, but this method often causes interference between the floor heating system and the heating system, and it is also necessary to have both the heating system and the floor heating system in one heat exchanger, which is a complex method with high operation and maintenance difficulty. SUMMARY

[0009] The application aims to provide a heating unit with reduced return water temperature and a method for reducing return water temperature, which can achieve the effect of low return water temperature without increasing radiator area, without needing absorption heat pump, without using electric heat pump, without reducing secondary network user flow, and without using cascade heat exchange.

[0010] To achieve the above-mentioned purpose, the application provides the following solutions.

[0011] The application provides a heating unit with reduced return water temperature, which comprises a unit controller, a room temperature sensor, a heat exchanger, an electric regulating valve and an electric on-off valve arranged at the primary network of the heat exchanger, and a secondary network water supply temperature transmitter, a secondary network return water temperature transmitter and a secondary network circulating pump arranged at the secondary network of the heat exchanger.

[0012] The room temperature sensor is used to collect an actual value of a user end room temperature.

[0013] The unit controller is internally provided with a secondary network water supply temperature regulator, and is connected with the room temperature sensor, the electric regulating valve, the electric on-off valve, the secondary network water supply temperature transmitter, the secondary network return water temperature transmitter and the secondary network circulating pump.

[0014] The unit controller is used to:

[0015] acquire unit operation data.

[0016] When the operation data indicates that the secondary network circulating pump operates at 100% design flow condition and the electric on-off valve is in an on condition, parameters of the secondary network water supply temperature regulator are set, and the valve position of the electric regulating valve is controlled to act according to the parameters of the secondary network water supply temperature regulator, so that the deviation between an actual value of the secondary network water supply temperature and a target value of the secondary network water supply temperature is within a set range.

[0017] According to the operation data and the on-off mode of the electric on-off valve, the secondary network return water temperature is regulated, and then the primary network return water temperature is regulated.

[0018] Optionally, the parameters of the secondary network water supply temperature regulator comprise a regulation period, a valve opening increment and a regulation water supply temperature dead zone.

[0019] Optionally, the unit controller is further used to:

[0020] set an upper target value and a lower target value of the secondary network return water temperature.

[0021] set an upper target value and a lower target value of the room temperature.

[0022] Optionally, the operation data at least comprises an actual value of the room temperature and an actual value of the secondary network return water temperature, and in terms of regulating the secondary network return water temperature according to the operation data and the on-off mode of the electric on-off valve, the unit controller is used to:

[0023] when the actual value of the room temperature is higher than the upper limit target value of the room temperature,

[0024] If the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature, the electric on-off valve is turned off and the secondary network circulating pump is kept running to regulate the secondary network return water temperature until the actual value of the secondary network return water temperature is lower than the lower limit target value of the secondary network return water temperature.

[0025] If the actual value of the secondary network return water temperature is lower than the lower limit target value of the secondary network return water temperature, the electric on-off valve is turned on and the secondary network circulating pump is kept running to regulate the secondary network return water temperature until the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature.

[0026] Optionally, the operating data at least includes the actual value of the room temperature and the actual value of the secondary network return water temperature, and in terms of regulating the secondary network return water temperature according to the operating data and the on-off mode of the electric on-off valve, the unit controller is configured to:

[0027] change the lower limit target value of the secondary network return water temperature when the actual value of the room temperature is lower than the upper limit target value of the room temperature;

[0028] If the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature, the electric on-off valve is turned off and the secondary network circulating pump is kept running to regulate the secondary network return water temperature until the actual value of the secondary network return water temperature is lower than the changed lower limit target value of the secondary network return water temperature.

[0029] If the actual value of the secondary network return water temperature is lower than the changed lower limit target value of the secondary network return water temperature, the electric on-off valve is turned on and the secondary network circulating pump is kept running to regulate the secondary network return water temperature until the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature.

[0030] Optionally, in terms of changing the lower limit target value of the secondary network return water temperature when the actual value of the room temperature is lower than the upper limit target value of the room temperature, the unit controller is configured to:

[0031] when the actual value of the room temperature is lower than the lower limit target value of the room temperature, the changed lower limit target value of the secondary network return water temperature is determined as thxj-Δth; thnj is the set lower limit target value of the secondary network return water temperature, thxj is the set upper limit target value of the secondary network return water temperature, and Δth is the difference value of the return water temperature.

[0032] when the actual value of the room temperature is higher than the lower limit target value of the room temperature and lower than the upper limit target value of the room temperature, the changed lower limit target value of the secondary network return water temperature is determined as thxj-2×Δth.

[0033] Optionally, the heat exchanger is further provided with a primary network water supply pipe and a primary network return water pipe connected with the heat exchanger; wherein a primary network water supply temperature transmitter, an electric regulating valve and an electric on-off valve are arranged in the primary network water supply pipe, and a primary network return water temperature transmitter is arranged in the primary network return water pipe.

[0034] Optionally, the heat exchanger is further provided with a secondary network water supply pipe and a secondary network return water pipe connected with the heat exchanger; wherein a secondary network water supply temperature transmitter is arranged on the secondary network water supply pipe; a secondary network circulating pump, a secondary network return water temperature transmitter and a secondary network return water pressure transmitter are arranged on the secondary network return water pipe.

[0035] Optionally, the application further comprises a host computer; the host computer is used for acquiring operation data collected by the unit controller and various instructions transmitted by the unit control.

[0036] The application further provides a method for reducing return water temperature of a heating unit, comprising the following steps:

[0037] acquiring operation data of the unit;

[0038] when the operation data indicates that the secondary network circulating pump is operated at 100% design flow condition and the electric on-off valve is in an on condition, setting parameters of a secondary network water supply temperature regulator, and controlling a valve position of an electric regulating valve according to the parameters of the secondary network water supply temperature regulator, so that the deviation between an actual value of the secondary network water supply temperature and a target value of the secondary network water supply temperature is within a set range;

[0039] controlling the secondary network return water temperature according to the operation data and the on-off mode of the electric on-off valve, and then controlling the primary network return water temperature.

[0040] According to the specific embodiments of the application, the following technical effects are achieved:

[0041] (1) The application is simple, effective and low in cost; the required low return water temperature can be obtained by modifying the unit structure of an existing heating unit according to the application and installing a unit controller according to the application.

[0042] (2) According to the method of the application, the secondary network return water temperature is reduced, the primary network return water temperature is also reduced, and the primary network temperature difference is increased, so that the heating area can be increased without changing the primary network flow.

[0043] (3) The total flow of the primary network is fluctuant, because the number of on-off of the electric on-off valves of all heating units is variable; due to the regulating effect of the electric regulating valve of the primary network, the hydraulic balance between the heating units in the on state of the electric on-off valve can be ensured.

[0044] (4) The secondary network water supply temperature is fluctuant, but the secondary network flow is stable, so the secondary network hydraulic disorder does not occur.

[0045] (5) The room temperature data is directly collected, and a room temperature feedback control scheme is adopted; the room temperature is somewhat fluctuant, but the thermal inertia of the building is very large, so the slight room temperature fluctuation does not affect the thermal user comfort. BRIEF DESCRIPTION OF DRAWINGS

[0046] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description only constitute some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0047] Figure 1 A structural block diagram of a low-return-temperature heat supply unit is provided for the embodiments of the present application;

[0048] Figure 2 A flowchart of a low-return-temperature method applied to a low-return-temperature heat supply unit is provided for the embodiments of the present application;

[0049] Figure 3 A structural diagram of a centralized heat source indirect heat supply unit with low-return-temperature is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments only constitute some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0051] The present application provides a low-return-temperature heat supply unit and a low-return-temperature method, which have the characteristics of reducing the return water temperature of the primary network, improving the transmission capacity of the primary network, improving the system efficiency, and reducing the heat supply cost, and have the characteristics of low cost and simple operation.

[0052] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0053] Embodiment One

[0054] The embodiments of the present application provide a low-return-temperature heat supply unit, which can realize low-return-temperature operation of the heat supply unit in a low-cost manner, effectively improve the transmission efficiency of the primary network, and improve the heat source operation efficiency.

[0055] The reduced return water temperature heating unit is configured with a unit controller according to the system characteristics where the unit is located, the unit controller controls the heating unit to operate in a reduced return water temperature mode, the function of the unit controller is to collect real-time operation data of the heating unit, set operation parameters of the heating unit, control a secondary network circulating pump, a primary network electric regulating valve, or a primary network electric on-off valve, or a primary network distributed pump, the unit controller also communicates with an upper computer of a heating monitoring system, and transmits real-time operation data and linkage information required by all heating units to the upper computer.

[0056] As shown in Figure 1 A reduced return water temperature heating unit provided by the embodiment of the present application, comprising: a unit controller, a room temperature sensor, a heat exchanger, an electric regulating valve and an electric on-off valve arranged at a primary network of the heat exchanger, and a secondary network water supply temperature transmitter, a secondary network return water temperature transmitter and a secondary network circulating pump arranged at a secondary network of the heat exchanger;

[0057] The room temperature sensor is used to collect an actual value of a user end room temperature; the unit controller is internally provided with a secondary network water supply temperature regulator; the unit controller is connected with the room temperature sensor, the electric regulating valve, the electric on-off valve, the secondary network water supply temperature transmitter, the secondary network return water temperature transmitter and the secondary network circulating pump respectively.

[0058] The unit controller is used to:

[0059] acquire unit operation data.

[0060] When the operation data indicates that the secondary network circulating pump operates at 100% design flow condition and the electric on-off valve is in an on condition, parameters of the secondary network water supply temperature regulator are set, and according to the parameters of the secondary network water supply temperature regulator, a valve position action of the electric regulating valve is controlled, so that the actual value of the secondary network water supply temperature deviates from a target value of the secondary network water supply temperature within a set range; the parameters of the secondary network water supply temperature regulator include a control period, a valve opening increment and a control water supply temperature dead zone.

[0061] According to the operation data and an on-off mode of the electric on-off valve, the secondary network return water temperature is controlled, and then the primary network return water temperature is controlled.

[0062] Preferably, the unit controller in the embodiment of the present application is also used to:

[0063] set an upper limit target value and a lower limit target value of the secondary network return water temperature, and set an upper limit target value and a lower limit target value of the room temperature.

[0064] Further, the operation data at least includes an actual value of room temperature and an actual value of secondary network return water temperature, and the unit controller is used for:

[0065] when the actual value of room temperature is higher than the upper limit target value of room temperature,

[0066] if the actual value of secondary network return water temperature is higher than the upper limit target value of secondary network return water temperature, the secondary network return water temperature is regulated by adopting the mode that the electric on-off valve is off and the secondary network circulating pump keeps running until the actual value of secondary network return water temperature is lower than the lower limit target value of secondary network return water temperature;

[0067] if the actual value of secondary network return water temperature is lower than the lower limit target value of secondary network return water temperature, the secondary network return water temperature is regulated by adopting the mode that the electric on-off valve is on and the secondary network circulating pump keeps running until the actual value of secondary network return water temperature is higher than the upper limit target value of secondary network return water temperature.

[0068] or,

[0069] when the actual value of room temperature is lower than the upper limit target value of room temperature, the lower limit target value of secondary network return water temperature is changed;

[0070] if the actual value of secondary network return water temperature is higher than the upper limit target value of secondary network return water temperature, the secondary network return water temperature is regulated by adopting the mode that the electric on-off valve is off and the secondary network circulating pump keeps running until the actual value of secondary network return water temperature is lower than the changed lower limit target value of secondary network return water temperature;

[0071] if the actual value of secondary network return water temperature is lower than the changed lower limit target value of secondary network return water temperature, the secondary network return water temperature is regulated by adopting the mode that the electric on-off valve is on and the secondary network circulating pump keeps running until the actual value of secondary network return water temperature is higher than the upper limit target value of secondary network return water temperature.

[0072] wherein, when the actual value of room temperature is lower than the upper limit target value of room temperature, the lower limit target value of secondary network return water temperature is changed, and the unit controller is used for:

[0073] when the actual value of room temperature is lower than the lower limit target value of room temperature, the changed lower limit target value of secondary network return water temperature is determined as thnj-Δth; thnj is the set lower limit target value of secondary network return water temperature, and Δth is the difference value of return water temperature;

[0074] when the actual value of room temperature is higher than the lower limit target value of room temperature and lower than the upper limit target value of room temperature, the changed lower limit target value of secondary network return water temperature is determined as thxj-2×Δth; thxj is the set upper limit target value of secondary network return water temperature.

[0075] Further, in the example of the present application, the heat exchanger primary net is further provided with a primary net water supply pipe and a primary net return water pipe connected with the heat exchanger; wherein a primary net water supply temperature transmitter, an electric regulating valve and an electric on-off valve are arranged in the primary net water supply pipe, and a primary net return water temperature transmitter is arranged in the primary net return water pipe.

[0076] The heat exchanger secondary net is further provided with a secondary net water supply pipe and a secondary net return water pipe connected with the heat exchanger; wherein a secondary net water supply temperature transmitter is arranged on the secondary net water supply pipe; a secondary net circulating pump, a secondary net return water temperature transmitter and a secondary net return water pressure transmitter are arranged on the secondary net return water pipe.

[0077] Preferably, the example of the present application further comprises a host computer; the host computer is used to acquire the operation data collected by the unit controller and the instructions transmitted by the unit control.

[0078] Example Two

[0079] As shown in Figure 2 The example of the present application provides a method for reducing return water temperature of a heat supply unit, which comprises the following steps:

[0080] Step 100: acquiring unit operation data.

[0081] Step 200: when the operation data indicates that the secondary net circulating pump is running at 100% design flow condition and the electric on-off valve is in the on condition, setting the parameters of the secondary net water supply temperature regulator, and controlling the valve position of the electric regulating valve according to the parameters of the secondary net water supply temperature regulator, so that the deviation between the actual value of the secondary net water supply temperature and the target value of the secondary net water supply temperature is within the set range.

[0082] Step 300: according to the operation data and the on-off mode of the electric on-off valve, regulating and controlling the secondary net return water temperature, and then regulating and controlling the primary net return water temperature.

[0083] The method for reducing return water temperature provided by the example of the present application can be used for centralized heat source indirect heat supply units, centralized heat source distributed pump indirect heat supply units, centralized heat source mixed water direct heat supply units, gas boiler indirect heat supply units, etc. Each heat supply unit is provided with a unit controller and corresponding hydraulic conveying equipment and instruments. The method for reducing return water temperature described in the example of the present application will be described taking the centralized heat source indirect heat supply unit with reduced return water temperature as an example.

[0084] The structure of the centralized heat source indirect heat supply unit with reduced return water temperature is shown in Figure 3As shown, the primary network water supply pipe 12 is sequentially connected with a primary network water supply pressure transmitter 11, a primary network water supply temperature transmitter 13, an electric regulating valve 17 and an electric on-off valve 18; the primary network return pipe 15 is connected with a primary network return pressure transmitter 14 and a primary network return temperature transmitter 16; the secondary network water supply pipe 23 is sequentially installed with a secondary network water supply temperature transmitter 25 and a secondary network water supply pressure transmitter 27; the secondary network return pipe 24 is sequentially installed with a secondary network circulating pump 21, a heat meter 22, a secondary network return temperature transmitter 26 and a secondary network return pressure transmitter 28, and the secondary network water supply pipe 23 and the secondary network return pipe 24 are connected with a heat user building 29; and the heat exchanger 19 is connected between the primary network and the secondary network.

[0085] The touch screen on the unit controller 4 is connected with the touch screen 1 and the gateway 2 through the gateway interface 3; the first analog input interface 8 is connected with the primary network water supply pressure transmitter 11, the primary network water supply temperature transmitter 13, the primary network return pressure transmitter 14 and the primary network return temperature transmitter 16; the second analog input interface 5 is connected with the secondary network water supply temperature transmitter 25, the secondary network water supply pressure transmitter 27, the secondary network return temperature transmitter 26 and the secondary network return pressure transmitter 28; the analog output interface 9 is connected with the secondary network circulating pump frequency converter 20, the electric regulating valve 17 and the electric on-off valve 18; the RS485 interface 10 is connected with the heat meter 22; and the room temperature and outdoor temperature interface 30 is connected with the room temperature sensor 6 and the outdoor temperature sensor 7. The secondary network circulating pump frequency converter 20 is also connected with the secondary network circulating pump 21.

[0086] The upper computer 31 in the dispatching room is used to acquire the operation data collected by the unit controller and perform remote monitoring.

[0087] The main function of the unit controller 4 is to acquire operation data, communicate with the upper computer 31, control the valve position of the electric regulating valve 17 and the electric on-off valve 18, and the unit controller 4 has a secondary network water supply temperature regulator inside, which can regulate the actual secondary network water supply temperature value according to the given secondary network water supply temperature target value, ensure that the actual secondary network water supply temperature value is equal to the secondary network water supply temperature target value, and realize the hydraulic balance of the primary network when the electric on-off valve 18 is in the on state.

[0088] A method for reducing return water temperature applied to the above-mentioned heat supply unit, comprising:

[0089] (1) After the normal operation of the above-mentioned heat supply unit, the unit controller acquires real-time operation data of the above-mentioned heat supply unit.

[0090] After the above heating unit is in normal operation, the real-time operation data collected by the unit controller includes primary network pressure, secondary network pressure, primary network water supply temperature, secondary network water supply temperature, primary network return water temperature, secondary network return water temperature, cumulative heat, cumulative flow, instantaneous heat, instantaneous flow, secondary network circulating pump frequency, valve opening of the electric regulating valve, valve state of the electric on-off valve, indoor temperature and outdoor temperature, etc.

[0091] (2) According to the real-time operation data, the primary network return water temperature of the above heating unit is reduced, specifically including:

[0092] S1: Set the parameters of the secondary network water supply temperature regulator inside the unit controller.

[0093] When the secondary network circulating pump is in 100% design flow condition, and the state of the electric on-off valve 18 is in the on state, the secondary network water supply temperature regulator controls the valve position of the electric regulating valve 17 to ensure that the actual value tgs of the secondary network water supply temperature of the heat exchanger is consistent with the target value tgj of the secondary network water supply temperature. The parameters of the secondary network water supply temperature regulator under the condition that the target value tgj of the secondary network water supply temperature is consistent are: control period Ti (range 0-300s, preferably 60s), valve opening increment ΔF (1%-5%, preferably 2%), and control water supply temperature dead zone ΔT (range ±3℃, preferably ±1℃).

[0094] Here, the value range of the target value tgdj of the secondary network water supply temperature of the floor heating is 50-60℃, and the preferred value is 55℃; the value range of the target value tggj of the secondary network water supply temperature of the wall heating is 60-70℃, and the preferred value is 65℃.

[0095] When the state of the electric on-off valve 18 is in the off state, the secondary network water supply temperature regulator does not act, and the valve position of the electric regulating valve 17 does not change.

[0096] S2: Set the upper limit target value thxj and the lower limit target value thnj of the secondary network return water temperature; wherein the value range of the upper limit target value thdxj of the secondary network return water temperature of the floor heating is 25-35℃, and the value range of the lower limit target value thdnj is 20-30℃, and the preferred values are thdxj=30℃ and thdnj=25℃; the value range of the upper limit target value thgxj of the secondary network return water temperature of the wall heating is 30-40℃, and the value range of the lower limit target value thgnj is 20-30℃, and the preferred values are thgxj=35℃ and thgnj=25℃.

[0097] S3: Set the target room temperature; wherein the value range of the upper limit target value tnxj of the room temperature is 18-24℃, and preferably the upper limit target value is 20℃; the value range of the lower limit target value tnnj of the room temperature is 18-22℃, and preferably the lower limit target value is 18℃.

[0098] S4: The electric on-off valve 18 regulates the secondary network return water temperature in on-off mode.

[0099] If the secondary network return water temperature actual value ths is higher than the upper limit target value thxj of the secondary network return water temperature, the state of the electric on-off valve 18 is controlled to be off, and the secondary network return water temperature actual value ths is waited to be lower than the lower limit target value thnj of the secondary network return water temperature.

[0100] If the secondary network return water temperature actual value ths is lower than the lower limit target value thnj of the secondary network return water temperature, the state of the electric on-off valve 18 is controlled to be on, and the secondary network return water temperature actual value ths is waited to be higher than the upper limit target value thxj of the secondary network return water temperature.

[0101] S5: If the room temperature actual value tns is lower than the lower limit target value tnnj of the room temperature, the lower limit target value thnj of the secondary network return water temperature is to be lowered (thdnj is the lower limit target value of the floor heating, and thgnj is the lower limit target value of the wall-mounted heating), where thdnj = thdxj - Δth (floor heating), and thgnj = thgxj - Δth (wall-mounted heating). Here, the difference Δth of the return water temperature is in the range of 2-5°C, and the preferred value is 3°C.

[0102] If the room temperature actual value tns is higher than the upper limit target value tnxj of the room temperature, the lower limit target value thnj of the secondary network return water temperature is kept unchanged.

[0103] If the room temperature actual value tns is higher than the lower limit target value tnnj of the room temperature and lower than the upper limit target value tnxj of the room temperature, the lower limit target value thnj of the secondary network return water temperature is thxj - 2 x Δth.

[0104] Example: A central heat source indirect heating system has 60 indirect heating units, a heating area of 3 million square meters, and the end heat dissipater is wall-mounted heating. In order to ensure the primary network delivery efficiency, the primary network return water temperature needs to be lowered and the system needs to be operated below 40°C. The difference between the secondary network supply water temperature and the secondary network return water temperature of these indirect heating units is between 5-8°C, and the room temperature is required to be between 18-20°C. According to the requirements, all the existing indirect heating units in the heating system are to be modified into indirect heating units with the function of lowering the return water temperature, and the corresponding unit control cabinet is configured, and the low return water temperature operation is realized according to the following method.

[0105] 1. Obtain the secondary network supply water temperature of each heat exchanger under the balanced working condition of the primary network.

[0106] First, make the secondary network circulating pump operate under the 100% design flow condition, and set the parameters of the secondary network supply water temperature regulator under the on condition of the electric on-off valve, i.e. the control period Ti = 60s, the valve opening increment ΔF = 2%, and the control supply water temperature dead zone ΔT = ±1°C.

[0107] Then, set the secondary network supply water temperature target value of all the heating heat exchangers as tgj=65℃, and the secondary network supply water temperature regulator of the unit controller automatically controls the secondary network supply water temperature actual value tgs of the heating heat exchangers to be consistent with the secondary network supply water temperature target value, so as to realize the hydraulic balance among the heat exchangers in the open state of the electric on-off valve.

[0108] 2, set the upper and lower limit target values of the secondary network return water temperature: the upper limit target value of the secondary network return water temperature of the heating is thgxj=38℃, and the lower limit target value is thgnj=25℃; the difference Δth is 3℃.

[0109] 3, set the upper limit target value of the room temperature as tnxj=20℃, and the lower limit target value of the room temperature as tnnj=18℃.

[0110] 4, the electric on-off valve 18 controls the return water temperature in an on-off manner

[0111] (1) if the room temperature actual value tns is higher than the upper limit target value of the room temperature tnxj=20℃, keep the lower limit target value of the secondary network return water temperature thgnj=25℃:

[0112] if the secondary network return water temperature actual value ths is higher than the upper limit target value of the secondary network return water temperature thgxj=38℃, the electric on-off valve is off, the secondary network circulating pump is normally operated, and then wait for the secondary network return water temperature actual value ths to be lower than the lower limit target value of the secondary network return water temperature thgnj=25℃.

[0113] if the secondary network return water temperature actual value ths is lower than the lower limit target value of the secondary network return water temperature thgnj=25℃, the electric on-off valve is on, and then wait for the secondary network return water temperature actual value ths to be higher than the upper limit target value of the secondary network return water temperature 38℃.

[0114] (2) if the room temperature actual value tns is lower than the lower limit target value of the room temperature tnnj=18℃: change the lower limit target value of the secondary network return water temperature, thgnj=38℃-3℃=35℃, here Δth takes the value range of 3℃.

[0115] if the secondary network return water temperature actual value ths is higher than the upper limit target value of the secondary network return water temperature thgxj=38℃, the electric on-off valve is off, and then wait for the secondary network return water temperature actual value ths to be lower than the changed lower limit target value of the secondary network return water temperature thgnj=35℃.

[0116] If the secondary network return water temperature actual value ths is lower than the changed lower limit target value of the secondary network return water temperature thgnj = 35℃, the electric on-off valve (18) is on, and then the secondary network return water temperature actual value ths is waited to be higher than the upper limit target value of the secondary network return water temperature thgxj = 38℃.

[0117] (3) If the room temperature actual value tns is higher than the lower limit target value of the room temperature tnnj = 18℃ and lower than the upper limit target value of the room temperature tnxj = 20℃, the lower limit target value of the return water temperature thgnj = 38℃ - 3℃ * 2 = 32℃ is changed, where the value range of Δth is 3℃. The subsequent steps are the same as step (2).

[0118] Further explanation is as follows:

[0119] (1) Process of increase of room temperature actual value of hot user

[0120] When the room temperature actual value tns is lower than the lower limit target value of the room temperature tnnj = 18℃ and the secondary network return water temperature actual value ths is lower than the lower limit target value of the secondary network return water temperature thgnj = 35℃, the electric on-off valve is on, the secondary network circulating pump is run, and the secondary network supply water temperature tgj = 65℃ hot water is sent to the user end; then after a period of time, the secondary network return water temperature actual value starts to rise, and when it exceeds the upper limit target value of the secondary network return water temperature thgxj = 38℃, the electric on-off valve is off; then the secondary network supply water temperature and the secondary network return water temperature tend to be consistent, and continue to circulate in the secondary network, the actual secondary network return water temperature continuously decreases, and when it is lower than the lower limit target value of the secondary network return water temperature thgnj = 35℃, the above process is continued until the room temperature actual value is higher than the upper limit of the room temperature 20℃.

[0121] (2) Process of decrease of room temperature actual value of hot user

[0122] When the room temperature actual value tns is higher than the upper limit target value of the room temperature tnxj = 20℃ and the secondary network return water temperature actual value ths is lower than the lower limit target value of the secondary network return water temperature thgnj = 25℃, the electric on-off valve is on, the secondary network circulating pump is run, and the secondary network supply water temperature tgj = 65℃ hot water is sent to the user end; then after a period of time, the secondary network return water temperature actual value starts to rise, and when it exceeds the upper limit target value of the secondary network return water temperature thgxj = 38℃, the electric on-off valve is off; then the secondary network supply water temperature and the secondary network return water temperature tend to be consistent, and continue to circulate in the secondary network, the actual secondary network return water temperature continuously decreases, and when it is lower than the lower limit target value of the secondary network return water temperature thgnj = 35℃, the above process is continued until the room temperature actual value is lower than the lower limit target value of the room temperature 18℃.

[0123] (3) It can be seen that the fluctuation range of the secondary network return water temperature during the temperature rising process of the heat user room is 35-38℃, and the average return water temperature is 36.5℃; while during the temperature decreasing process of the heat user room, the fluctuation range of the secondary network return water temperature is 25-38℃, and the average return water temperature is 33℃, that is, when the actual value of the room temperature is lower than 18℃, a temperature rising process is started; when the actual value of the room temperature is higher than 20℃, a temperature decreasing process is started. Therefore, the room temperature fluctuates between 18-20℃.

[0124] (4) In order to avoid the room temperature from fluctuating too fast, an intermediate process is added, in which the actual value of the room temperature tns is greater than 18℃ and less than 20℃, during which the fluctuation range of the secondary network return water temperature is 32-38℃, and the average return water temperature is 35℃.

[0125] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0126] The principles and implementation manners of the present application are described by using specific examples in the specification. The above description of the embodiments is only for helping to understand the method of the present application and its core idea; meanwhile, for the general technical personnel in the field, the specific implementation manners and application range of the present application can be changed according to the idea of the present application. In conclusion, the content of the specification should not be understood as the limitation of the present application.

Claims

1. A heating unit for reducing return water temperature, characterized in that, include: The unit controller, room temperature sensor, heat exchanger, electric regulating valve and electric on / off valve installed at the primary network of the heat exchanger, and secondary network supply water temperature transmitter, secondary network return water temperature transmitter and secondary network circulation pump installed at the secondary network of the heat exchanger. The room temperature sensor is used to collect the actual room temperature value at the user end; The unit controller is equipped with a secondary network water supply temperature regulator; the unit controller is connected to a room temperature sensor, an electric regulating valve, an electric on / off valve, a secondary network water supply temperature transmitter, a secondary network return water temperature transmitter, and a secondary network circulation pump. The unit controller is used for: Obtain unit operating data; When the operating data indicates that the secondary network circulation pump is operating at 100% of its design flow rate and the electric on / off valve is in the on / off state, the parameters of the secondary network water supply temperature regulator are set, and the valve position action of the electric regulating valve is controlled according to the parameters of the secondary network water supply temperature regulator to ensure that the deviation between the actual value of the secondary network water supply temperature and the target value of the secondary network water supply temperature is within the set range; the parameters of the secondary network water supply temperature regulator include the control cycle, valve opening increment, and control water supply temperature dead zone; Based on the operating data and the on / off mode of the electric on / off valve, the return water temperature of the secondary network is adjusted, thereby adjusting the return water temperature of the primary network. The operating data includes at least the actual room temperature value and the actual return water temperature of the secondary network.

2. The heating unit for reducing return water temperature according to claim 1, characterized in that, The unit controller is also used for: Set the upper and lower target values ​​for the secondary network return water temperature; Set the upper and lower target values ​​for room temperature.

3. A heating unit for reducing return water temperature according to claim 2, characterized in that, Regarding the regulation of the secondary network return water temperature based on operating data and the on / off mode of the electric on / off valve, the unit controller is used for: When the actual room temperature is higher than the upper limit target value, If the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature, the secondary network return water temperature is regulated by using an electric on / off valve to shut off the secondary network while the secondary network circulation pump continues to run, until the actual value of the secondary network return water temperature is lower than the lower limit target value of the secondary network return water temperature. If the actual value of the secondary network return water temperature is lower than the lower limit target value of the secondary network return water temperature, the secondary network return water temperature is regulated by using an electric on / off valve and keeping the secondary network circulation pump running until the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature.

4. A heating unit for reducing return water temperature according to claim 2, characterized in that, The operating data includes at least the actual room temperature and the actual secondary network return water temperature. Regarding the regulation of the secondary network return water temperature based on the operating data and the on / off mode of the electric on / off valve, the unit controller is used for: When the actual room temperature is lower than the upper limit target value, change the lower limit target value of the secondary network return water temperature. If the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature, the secondary network return water temperature is regulated by using an electric on / off valve to shut off the secondary network while the secondary network circulation pump continues to run, until the actual value of the secondary network return water temperature is lower than the lower limit target value of the modified secondary network return water temperature. If the actual value of the secondary network return water temperature is lower than the revised lower limit target value of the secondary network return water temperature, the secondary network return water temperature will be regulated by using an electric on / off valve and keeping the secondary network circulation pump running until the actual value of the secondary network return water temperature is higher than the upper limit target value of the secondary network return water temperature.

5. A heating unit for reducing return water temperature according to claim 4, characterized in that, Regarding changing the lower limit target value of the secondary network return water temperature when the actual room temperature is lower than the upper limit target value, the unit controller is configured to: When the actual room temperature is lower than the lower limit target value of the room temperature, the lower limit target value of the secondary network return water temperature is determined as thxj-Δth; thnj is the set lower limit target value of the secondary network return water temperature, thxj is the set upper limit target value of the secondary network return water temperature; Δth is the difference in return water temperature. When the actual room temperature is higher than the lower limit target value but lower than the upper limit target value, the lower limit target value of the secondary network return water temperature will be determined as thxj-2×Δth.

6. A heating unit for reducing return water temperature according to claim 1, characterized in that, The heat exchanger is also equipped with a primary water supply pipe and a primary water return pipe connected to the heat exchanger; wherein, the primary water supply temperature transmitter, the electric regulating valve and the electric on / off valve are installed in the primary water supply pipe, and the primary water return temperature transmitter is installed in the primary water return pipe.

7. A heating unit for reducing return water temperature according to claim 6, characterized in that, The heat exchanger is also equipped with a secondary network water supply pipe and a secondary network water return pipe connected to the heat exchanger; wherein, the secondary network water supply temperature transmitter is installed on the secondary network water supply pipe; the secondary network circulation pump, the secondary network water return temperature transmitter, and the secondary network water return pressure transmitter are installed on the secondary network water return pipe.

8. A heating unit for reducing return water temperature according to claim 1, characterized in that, It also includes a host computer; the host computer is used to acquire the operating data collected by the unit controller and various instructions transmitted by the unit control.

9. A method for reducing the return water temperature in a heating unit for reducing return water temperature as described in any one of claims 1-8, characterized in that, include: Obtain unit operating data; When the operating data indicates that the secondary network circulation pump is operating at 100% of the design flow rate and the electric on / off valve is in the on state, set the parameters of the secondary network water supply temperature regulator, and control the valve position action of the electric regulating valve according to the parameters of the secondary network water supply temperature regulator, so that the deviation between the actual value of the secondary network water supply temperature and the target value of the secondary network water supply temperature is within the set range. Based on the operating data and the on / off mode of the electric on / off valve, the return water temperature of the secondary network is adjusted, thereby adjusting the return water temperature of the primary network.

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