Method and system for determining backpressure of condenser based on unit power and circulating water temperature

Abstract

The invention discloses a method and system for determining the backpressure of a condenser based on unit power and circulating water temperature, and is suitable for the technical field of power generation. The method comprises the steps of firstly calculating circulating water outlet temperature according to current load, condenser thermal load and circulating water flow; then, the saturation pressure and the circulating water density are determined through the temperature; calculating the flow velocity in the cooling pipe by combining the condenser cooling pipe parameters, and determining the total heat transfer coefficient by considering the correction coefficient; the condenser end difference is calculated according to the circulating water temperature rise, the total heat transfer coefficient and the like; and finally, determining the backpressure of the condenser and controlling the circulating pump to operate according to the backpressure. By accurately calculating the back pressure of the condenser, the economical efficiency of unit operation is effectively improved, the production cost and the power supply coal consumption are reduced, and technical support is provided for energy conservation and consumption reduction of power generation enterprises. The method has the advantages of being accurate in calculation, high in practicability and the like, and sustainable development of the power generation industry is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power generation, in particular to a method and system for determining condenser back pressure based on unit power and circulating water temperature. BACKGROUND

[0002] At present, the situation of power production and operation is becoming increasingly severe, and continuous cost reduction and efficiency improvement and operation efficiency improvement are important indicators for power enterprises. Therefore, how to reduce production cost, reduce power supply coal consumption, enhance competitiveness and obtain maximum profit while ensuring safety production is increasingly important.

[0003] The problem of turbine cold-end circulating water optimization operation is very prominent in all power generation enterprises. At the same time, the optimization operation of turbine cold-end circulating water is an application technology with significant energy saving and consumption reduction, which has less investment, short construction and technical improvement period and fast effective income. The optimization operation of circulating water system is essentially to find the relationship among back pressure, condensate water temperature and condenser circulating water flow of the unit operation according to the load and circulating water inlet temperature of the unit, and reasonably configure the operation mode of circulating pump, so as to improve the economy of the unit, which has great significance for realizing energy saving and consumption reduction of power plant. SUMMARY

[0004] In view of the problems in the prior art, the present application provides a method and system for determining condenser back pressure based on unit power and circulating water temperature, which can determine the corresponding relationship between the back pressure and different unit power and circulating water inlet temperature, improve the accuracy of back pressure calculation, reasonably configure the operation mode of circulating pump, and improve the economy of the unit.

[0005] The present application is realized by the following technical solutions: The method and system for determining condenser back pressure based on unit power and circulating water temperature comprise the following steps: Step 1, determining the circulating water outlet temperature according to the condenser heat load under the current load, the measured circulating water flow of the condenser and the set constant pressure ratio heat of the unit; Step 2, determining the saturation pressure according to the circulating water outlet temperature, and determining the density of circulating water outlet according to the saturation pressure and the circulating water outlet temperature; Step 3, determining the condenser cooling pipe flow velocity according to the condenser cooling water density, the set condenser flow number of the unit, the measured circulating water flow of the condenser, the condenser cooling pipe number and the condenser cooling pipe inner diameter; Step 4, determining the total heat transfer coefficient according to the condenser cooling pipe flow velocity and the correction coefficient of the unit; Step 5, determining the condenser end difference according to the circulating water temperature rise, the total heat transfer coefficient, the condenser cooling area, the set constant pressure ratio heat of the unit and the measured circulating water flow of the condenser; Step 6, determine the condenser back pressure according to the condenser terminal difference and the circulating water temperature rise, and control the operation mode of the circulating pump of the unit according to the condenser back pressure.

[0006] Preferably, the method for determining the condenser heat load under the current load is as follows: Determine the condenser heat load under the current load according to the rated power of the unit and the rated condenser heat load. Condenser heat load = current load / rated power of the unit * rated condenser heat load.

[0007] Preferably, the method for calculating the circulating water temperature rise is as follows: Circulating water temperature rise = condenser heat load / specific heat at constant pressure set for the unit / measured circulating water flow rate of the condenser * 1000 / 3.6.

[0008] Preferably, the method for determining the circulating water outlet temperature is as follows: Determine the circulating water temperature rise according to the condenser heat load under the current load, the measured circulating water flow rate of the condenser, and the specific heat at constant pressure set for the unit. Determine the circulating water outlet temperature according to the circulating water temperature rise and the circulating water inlet temperature.

[0009] Preferably, the method for determining the density of the circulating water outlet is as follows: Determine the saturation pressure according to the saturationPressureT function and in combination with the circulating water outlet temperature. Determine the density of the circulating water outlet according to the saturation pressure, the circulating water outlet temperature, and in combination with the densityPT function.

[0010] Preferably, the method for determining the total heat transfer coefficient according to the flow rate in the condenser cooling pipe and the correction coefficient of the unit comprises: The correction coefficient comprises a pipe diameter correction coefficient, a cleaning coefficient, a cooling water temperature correction coefficient, and a wall thickness correction coefficient.

[0011] Preferably, the method for calculating the total heat transfer coefficient sngKHEI is as follows: Total heat transfer coefficient sngKHEI = pipe diameter correction coefficient * cleaning coefficient * cooling water temperature correction coefficient * wall thickness correction coefficient * square root of the flow rate in the condenser cooling pipe.

[0012] Preferably, the method for determining the condenser back pressure according to the condenser terminal difference and the circulating water temperature rise comprises: Determine the condensate temperature according to the condenser terminal difference and the circulating water temperature rise, and determine the condenser back pressure according to the saturationPressureT function and the condensate temperature.

[0013] The method and system for determining the condenser back pressure based on the unit power and the circulating water temperature comprise: a circulating water outlet temperature module for determining the circulating water outlet temperature according to the condenser heat load under the current load, the measured circulating water flow of the condenser and the set constant pressure specific heat of the unit; a circulating water density module for determining the saturated pressure according to the circulating water outlet temperature, and determining the density of the circulating water outlet according to the saturated pressure and the circulating water outlet temperature; a cooling pipe flow rate module for determining the condenser cooling pipe flow rate according to the condenser cooling water density, the set condenser flow number of the unit, the measured circulating water flow of the condenser, the condenser cooling pipe number and the condenser cooling pipe inner diameter; a heat transfer coefficient module for determining the total heat transfer coefficient according to the condenser cooling pipe flow rate and the correction coefficient of the unit; a condenser terminal temperature difference module for determining the condenser terminal temperature difference according to the circulating water temperature rise, the total heat transfer coefficient, the condenser cooling area, the set constant pressure specific heat of the unit and the measured circulating water flow of the condenser; a condenser back pressure module for determining the condenser back pressure according to the condenser terminal temperature difference and the circulating water temperature rise, and controlling the operation mode of the circulating pump of the unit according to the condenser back pressure.

[0014] An electronic device comprises: a memory for storing a computer program; a processor for implementing the steps of the method for determining the condenser back pressure based on the unit power and the circulating water temperature when executing the computer program.

[0015] Compared with the prior art, the present application has the following beneficial technical effects: The method and system for determining the condenser back pressure based on the unit power and the circulating water temperature provided by the present application determine the circulating water outlet temperature according to the condenser heat load under the current load, the measured circulating water flow of the condenser and the set constant pressure specific heat of the unit, and then derive the saturated pressure, the density of the circulating water outlet, the condenser cooling pipe flow rate, the total heat transfer coefficient, the condenser terminal temperature difference and finally the condenser back pressure. The whole calculation process is logically rigorous, ensuring the accuracy and reliability of the back pressure calculation. The method not only comprehensively considers the two key factors of the unit power and the circulating water temperature, but also introduces a correction coefficient to further optimize the calculation result, so that the determination of the back pressure is more close to the actual operation, improving the accuracy and practicability of the calculation. In addition, the scheme reasonably configures the operation mode of the circulating pump, effectively improves the unit economy, helps to reduce the production cost and the power supply coal consumption, thereby enhancing the market competitiveness of the power enterprise.

[0016] The application also provides a method and system for determining condenser back pressure based on unit power and circulating water temperature, an electronic device and a computer storage medium, which have all the advantages of the method for determining condenser back pressure based on unit power and circulating water temperature. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0018] Figure 1 Flow chart for obtaining condenser cooling water density sngrou of the present application; Figure 2 Flow chart for obtaining condenser back pressure sngPs of the present application. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all. The components of the embodiments of the present application described and shown in the drawings can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0021] The method and system for determining condenser back pressure based on unit power and circulating water temperature comprises the following steps: Step 1, determining condenser heat load sngQ under current load according to unit rated power and rated condenser heat load; The calculation method of condenser heat load sngQ under current load is as follows: Condenser heat load sngQ = current load / unit rated power * rated condenser heat load.

[0022] Step 2, determining circulating water temperature rise sngdeltaT according to condenser heat load sngQ under current load, condenser measured circulating water flow sngW and unit set constant pressure specific heat sngCw; The calculation method of the circulating water temperature rise sngdeltaT is as follows: Circulating water temperature rise sngdeltaT = condenser heat load / unit set specific heat at constant pressure / measured circulating water flow of condenser * 1000 / 3.6.

[0023] Step 3, according to the circulating water temperature rise sngdeltaT and the circulating water inlet temperature t, the circulating water outlet temperature sngt2 is determined; The calculation method of the circulating water outlet temperature sngt2 is as follows: Circulating water outlet temperature sngt2 = circulating water temperature rise + circulating water inlet temperature.

[0024] Step 4, according to the circulating water outlet temperature sngt2, the condenser cooling water density sngrou is calculated; The calculation method of the condenser cooling water density sngrou is as follows: According to the saturationPressureT function and combined with the circulating water outlet temperature sngt2, the saturation pressure p is determined; According to the saturation pressure p, the circulating water outlet temperature sngt2 and combined with the densityPT function, the density of the circulating water outlet (sngrou) is determined.

[0025] According to the saturationPressureT function in IAPWS-IF97 (industrial standard formulated by International Association for the Properties of Water and Steam), the circulating water outlet temperature sngt2 obtained above is calculated to obtain the saturation pressure (p), that is, the circulating water outlet temperature sngt2 corresponds to the saturation pressure p = saturationPressureT (sngt2).

[0026] According to the densityPT function in IAPWS-IF97 (industrial standard formulated by International Association for the Properties of Water and Steam), the saturation pressure (p) calculated above and the circulating water outlet temperature sngt2 obtained above are calculated to obtain the density of the circulating water outlet (sngrou), that is, the condenser cooling water density sngrou obtained in step 4 is densityPT (p, sngt2).

[0027] Step 5, according to the condenser cooling water density sngrou and the unit set condenser flow number sngZ, the measured circulating water flow of condenser sngW, the condenser cooling pipe number sngN and the condenser cooling pipe inner diameter sngd2, the condenser cooling pipe inner flow velocity sngV is determined; The calculation method of the condenser cooling pipe inner flow velocity sngV is as follows: The flow rate in the condenser cooling pipe sngV = the number of condenser flow processes * the measured circulating water flow rate of the condenser / the density of the condenser cooling water / the number of condenser cooling pipes / the inner diameter of the condenser cooling pipe.

[0028] Step 6, according to the flow rate in the condenser cooling pipe sngV and the correction coefficient of the unit, determine the total heat transfer coefficient sngKHEI.

[0029] The correction coefficient includes the pipe diameter correction coefficient sngC1, the cleaning coefficient sngC2, the cooling water temperature correction coefficient sngC3 and the wall thickness correction coefficient sngC4.

[0030] The calculation method of the total heat transfer coefficient sngKHEI is as follows: The total heat transfer coefficient sngKHEI = the pipe diameter correction coefficient * the cleaning coefficient * the cooling water temperature correction coefficient * the wall thickness correction coefficient * the square root of the flow rate in the condenser cooling pipe.

[0031] Step 7, according to the circulating water temperature rise sngdeltaT, the total heat transfer coefficient sngKHEI, and the condenser cooling area sngA, the specific heat at constant pressure set by the unit sngCw and the measured circulating water flow rate of the condenser sngW, determine the condenser terminal difference sngT; The calculation method of the condenser terminal difference sngT is as follows: According to the total heat transfer coefficient sngKHEI * the condenser cooling area / the specific heat at constant pressure set by the unit / the measured circulating water flow rate of the condenser, calculate the value N; According to the circulating water temperature rise sngdeltaT and the value N, determine the condenser terminal difference sngT, as follows: Condenser terminal difference sngT = circulating water temperature rise sngdeltaT / (e^N - 1) Where e^N is the Nth power of the natural constant e.

[0032] Step 8, according to the condenser terminal difference sngT obtained in step 7 and the circulating water temperature rise sngdeltaT obtained in step 2, calculate the condensate temperature sngtc; The calculation method of the condensate temperature sngtc is as follows: Condensate temperature sngtc = circulating water inlet temperature + circulating water temperature rise + condenser terminal difference Step 9, according to the condensate temperature sngtc obtained in step 8, calculate the condenser back pressure sngPs; The calculation method of the condenser back pressure sngPs is as follows: According to the saturationPressureT function and the condensate temperature sngtc, determine the condenser back pressure sngPs.

[0033] The condenser back pressure sngPs is calculated according to the saturationPressureT function in IAPWS-IF97 (industrial standard formulated by the International Association for the Properties of Water and Steam) and the condensing water temperature sngtc, and the condensing water temperature sngtc corresponds to the condenser back pressure sngPs=saturationPressureT(sngtc).

[0034] The method for determining the condenser back pressure based on the unit power and the circulating water temperature comprehensively considers the load of different units and the circulating water inlet temperature, and combines the relationship between the measured circulating water flow of the condenser, reasonably configures the operation mode of the circulating pump and the overall angle of the condenser, improves the economy of the unit, is more practical and comprehensive, has better guidance for the optimal circulating pump mode pushed by actual operation, and can effectively reduce the operation cost of the gas turbine combined cycle heating unit. The method not only can be used for the above-mentioned actual operation scene, but also can provide corresponding ideas and methods for other optimization scenes, so as to obtain certain economic benefits in actual operation and complete the target of reducing cost and increasing benefit.

[0035] Embodiment 1 Taking the current load (Load) as 800 MW, the circulating water inlet temperature (t) as 16℃, the rated power of the unit (W_G_ED) as 1000 MW, the rated condenser heat load (sngQe) as 3207600 MJ / h, the set constant pressure ratio heat (sngCw) of the unit as 4183 J / (kg℃), the measured circulating water flow (sngW) of the condenser as 43855 kg / s, the set condenser flow number (sngZ) of the unit as 1, the condenser cooling pipe number (sngN) of the unit as 42508, the condenser cooling pipe inner diameter (sngd2) of the unit as 24 mm, the pipe diameter correction coefficient (sngC1) of the unit as 2706, the cleaning coefficient (sngC2) of the unit as 0.85, the cooling water temperature correction coefficient (sngC3) of the unit as 0.91, the wall thickness correction coefficient (sngC4) of the unit as 0.83, and the condenser cooling area (sngA) of the unit as 38000㎡ as examples. Based on the above working condition, the method and system for determining the condenser back pressure based on the unit power and the circulating water temperature according to the application include the following steps: Step 1, the condenser heat load sngQ under the current load is calculated as follows: The condenser heat load sngQ=the current load / the rated power of the unit*the rated condenser heat load.

[0036] Then, the condenser heat load under the current load is as follows according to the above example data: sngQ=800 / 1000*3207600=2566080 MJ / h Step 2, the calculation method of the circulating water temperature rise sngdeltaT is as follows: Circulating water temperature rise sngdeltaT = condenser heat load / unit set specific heat at constant pressure / condenser measured circulating water flow * 1000 / 3.6.

[0037] Then, according to the example data above, the circulating water temperature rise is as follows: sngdeltaT = 2566080 / 4183 / 43855 * 1000 / 3.6 = 3.89℃ Step 3, the calculation method of the circulating water outlet temperature sngt2 is as follows: Circulating water outlet temperature sngt2 = circulating water temperature rise + circulating water inlet temperature.

[0038] Then, according to the example data above, the circulating water outlet temperature sngt2 = 3.89 + 16 = 19.89℃ Step 4, the calculation method of the condenser cooling water density sngrou is as follows: The circulating water outlet temperature sngt2 calculated in the above "Step 3" is used to calculate the saturation pressure (p), and then the circulating water outlet temperature sngt2 corresponds to the saturation pressure p = saturationPressureT(sngt2).

[0039] Then, according to the example data above, the circulating water outlet temperature sngt2 is 19.89℃, and the corresponding saturation pressure p = saturationPressureT(19.89) = 0.023226 bar.

[0040] The saturation pressure (p) calculated above and the circulating water outlet temperature sngt2 calculated in the above "Step 3" are used to calculate the density of the circulating water outlet sngrou = densityPT(p, sngt2); Then, according to the example data above, the circulating water outlet temperature sngt2 is 19.89℃, and the corresponding saturation pressure p is 0.023226 bar, i.e. 2322.6 pa, so the density of the circulating water outlet sngrou = densityPT(0.023226, 293.04) = 998.56 kg / m3; Note: Here, 19.89℃ Celsius needs to be converted to Kelvin, i.e. 19.89 + 273.15 = 293.04 K Step 5, the calculation method of the condenser cooling pipe flow rate sngV is as follows: Condenser cooling pipe flow rate sngV = condenser flow number * condenser measured circulating water flow / condenser cooling water density / condenser cooling pipe number / condenser cooling pipe inner diameter.

[0041] Then, with the above example data, the flow rate in the condenser cooling pipe is as follows: sngV = 1 * 1.273 * 43855 / 998.56 / 42508 / 0.024 / 0.024 = 2.28 m / s Step 6, the calculation method of the total heat transfer coefficient sngKHEI is as follows: Total heat transfer coefficient sngKHEI = pipe diameter correction coefficient * cleanliness coefficient * cooling water temperature correction coefficient * wall thickness correction coefficient * square root of the flow rate in the condenser cooling pipe.

[0042] Then, with the above example data, the flow rate in the condenser cooling pipe sngKHEI = 2706 * 0.85 * 0.91 * 0.83 * sqrt(2.28) = 2625.65 W / (m2℃) Step 7, the calculation method of the condenser terminal difference sngT is as follows: The total heat transfer coefficient sngKHEI obtained by calculation in the above "Step 6" is multiplied by the condenser cooling area / the specific heat at constant pressure set by the unit / the measured circulating water flow rate of the condenser to calculate a value N; Then, with the above example data, the value N = 2625.65 * 38000 / 4183 / 43855 = 0.543; According to the circulating water temperature rise sngdeltaT obtained by calculation in the above "Step 2", the condenser terminal difference sngT in Step 7 is calculated as sngT = circulating water temperature rise sngdeltaT / (e^N - 1), where e^N is the Nth power of the natural constant e, and then sngT = 3.89 / (e^0.543 - 1) = 5.37℃; Step 8, the calculation method of obtaining the condensate temperature sngtc is as follows: Condensate temperature sngtc = circulating water inlet temperature + circulating water temperature rise ("Step 2" has been obtained) + condenser terminal difference ("Step 7" has been obtained), then with the above example data, condensate temperature sngtc = 16 + 3.89 + 5.37 = 25.26℃; Step 9, the calculation method of obtaining the condenser back pressure sngPs is as follows: The condensate temperature sngtc obtained by calculation in the above "Step 8" is used to calculate the condenser back pressure sngPs, and the condensate temperature sngtc corresponds to the condenser back pressure sngPs = saturationPressureT(sngtc) Then, with the example data above, the condensate water temperature sngtc is 25.26℃, and the corresponding back pressure sngPs=saturationPressureT(25.26)=3.21kPa; The method and system for determining the condenser back pressure based on the unit power and the circulating water temperature provided by the application are more practical and comprehensive, have better guidance for the optimal circulating pump mode pushed by the actual operation, and can effectively reduce the operation cost of the gas turbine combined cycle heat supply unit. The method can not only be used for the actual operation business processing scene as exemplified above, but also can provide corresponding ideas and methods for other optimization scenes.

[0043] Correspondingly, the application also provides a method and system for determining the condenser back pressure based on the unit power and the circulating water temperature, comprising: A circulating water outlet temperature module is configured to determine the circulating water outlet temperature according to the condenser heat load under the current load, the measured circulating water flow of the condenser, and the set constant pressure specific heat of the unit. A circulating water density module is configured to determine the saturated pressure according to the circulating water outlet temperature, and determine the density of the circulating water outlet according to the saturated pressure and the circulating water outlet temperature. A cooling pipe flow rate module is configured to determine the condenser cooling pipe flow rate according to the condenser cooling water density, the set condenser flow number of the unit, the measured circulating water flow of the condenser, the condenser cooling pipe number, and the condenser cooling pipe inner diameter. A heat transfer coefficient module is configured to determine the total heat transfer coefficient according to the condenser cooling pipe flow rate and the correction coefficient of the unit. A condenser terminal difference module is configured to determine the condenser terminal difference according to the circulating water temperature rise, the total heat transfer coefficient, the condenser cooling area, the set constant pressure specific heat of the unit, and the measured circulating water flow of the condenser. A condenser back pressure module is configured to determine the condenser back pressure according to the condenser terminal difference and the circulating water temperature rise, and control the operation mode of the circulating pump of the unit according to the condenser back pressure.

[0044] It should be noted that in the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can be implemented in other manners. For example, the division of the above-described apparatus embodiments is merely an example, and each module can be integrated into another module, or some features can be ignored, or not executed. The illustrated modules can be or can not be physically separate, and the modules illustrated as separate components can be or can not be physical units, i.e., can be located in one place or distributed to multiple places. According to actual needs, some or all of the modules can be selected to implement the purposes of the embodiments.

[0045] In addition, each module in the various embodiments of the present application can be integrated in a processing unit, or each module can be physically present separately, or two or more modules can be integrated in a unit. The above-mentioned integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0046] The electronic device provided in the embodiments of the present application includes a memory and a processor, the memory stores a computer program, and the processor implements the steps of the method for determining the condenser back pressure based on the unit power and the circulating water temperature according to any one of the above embodiments when executing the computer program.

[0047] The electronic device provided in another embodiment of the present application can further include: an input port connected to the processor, configured to transmit the multi-modal data collected by an external collection device to the processor; a display unit connected to the processor, configured to display the processing result of the processor to the outside world; and a communication module connected to the processor, configured to realize the communication between the electronic device and the outside world. The display unit can be a display panel, a laser scanning display, etc. The communication mode adopted by the communication module includes but is not limited to mobile high-definition link technology (HML), universal serial bus (USB), high-definition multimedia interface (HDMI), wireless connection (including wireless fidelity technology (WiFi), Bluetooth communication technology, low-power Bluetooth communication technology, and IEEE 802.11s-based communication technology).

[0048] The computer readable storage medium provided in the embodiments of the present application stores a computer program, and the computer program is executed by the processor to implement the steps of the method for determining the condenser back pressure based on the unit power and the circulating water temperature according to any one of the above embodiments.

[0049] The system for determining condenser back pressure based on unit power and circulating water temperature, the electronic device, and the related part of the computer readable storage medium provided in the embodiments of the present application are described in detail in the corresponding part of the method for determining condenser back pressure based on unit power and circulating water temperature provided in the embodiments of the present application, which will not be described here. In addition, the part of the above technical solutions provided in the embodiments of the present application that is consistent with the implementation principle of the corresponding technical solutions in the prior art is not described in detail, so as not to be too redundant.

[0050] The above is only an illustration of the technical idea of the present application, and cannot limit the protection scope of the present application. Any modification made according to the technical idea of the present application on the basis of the technical solutions falls within the protection scope of the claims of the present application.

Claims

1. A method and system for determining condenser back pressure based on unit power and circulating water temperature, characterized in that, The method comprises the following steps: Step 1, determining the outlet temperature of the circulating water according to the condenser heat load under the current load, the measured circulating water flow of the condenser and the set constant pressure ratio heat of the unit; Step 2, determining the saturation pressure according to the outlet temperature of the circulating water, and determining the density of the circulating water outlet water according to the saturation pressure and the outlet temperature of the circulating water; Step 3, determining the flow rate in the condenser cooling pipe according to the condenser cooling water density, the set condenser flow number of the unit, the measured circulating water flow of the condenser, the condenser cooling pipe number and the condenser cooling pipe inner diameter; Step 4, determining the total heat transfer coefficient according to the flow rate in the condenser cooling pipe and the correction coefficient of the unit; Step 5, determining the condenser terminal difference according to the circulating water temperature rise, the total heat transfer coefficient, the condenser cooling area, the set constant pressure ratio heat of the unit and the measured circulating water flow of the condenser; Step 6, determining the condenser back pressure according to the condenser terminal difference and the circulating water temperature rise, and controlling the operation mode of the circulating pump of the unit according to the condenser back pressure.

2. The method and system for determining condenser back pressure based on unit power and circulating water temperature as claimed in claim 1, wherein, The determination method of the condenser heat load under the current load is as follows: determining the condenser heat load under the current load according to the rated power of the unit and the rated condenser heat load; condenser heat load = current load / rated power of the unit * rated condenser heat load.

3. The method and system for determining condenser back pressure based on unit power and circulating water temperature as claimed in claim 1 wherein, The calculation method of the circulating water temperature rise is as follows: circulating water temperature rise = condenser heat load / set constant pressure ratio heat of the unit / measured circulating water flow of the condenser * 1000 / 3.

6.

4. The method and system for determining condenser back pressure based on unit power and circulating water temperature as claimed in claim 1, wherein, The determination method of the outlet temperature of the circulating water is as follows: determining the circulating water temperature rise according to the condenser heat load under the current load, the measured circulating water flow of the condenser and the set constant pressure ratio heat of the unit; determining the outlet temperature of the circulating water according to the circulating water temperature rise and the inlet temperature of the circulating water.

5. The method and system for determining condenser back pressure based on unit power and circulating water temperature as claimed in claim 1, wherein, The determination method of the density of the circulating water outlet water is as follows: determining the saturation pressure according to the saturationPressureT function and the outlet temperature of the circulating water; determining the density of the circulating water outlet water according to the saturation pressure, the outlet temperature of the circulating water and the densityPT function.

6. The method and system for determining condenser back pressure based on unit power and circulating water temperature as claimed in claim 1, wherein, The determination of the total heat transfer coefficient according to the flow rate in the condenser cooling pipe and the correction coefficient of the unit comprises: the correction coefficient comprises a pipe diameter correction coefficient, a cleaning coefficient, a cooling water temperature correction coefficient and a wall thickness correction coefficient.

7. The method and system for determining condenser back pressure based on unit power and circulating water temperature as claimed in claim 6 wherein, The calculation method of the total heat transfer coefficient is as follows: total heat transfer coefficient = pipe diameter correction coefficient * cleaning coefficient * cooling water temperature correction coefficient * wall thickness correction coefficient * square root of the flow rate in the condenser cooling pipe.

8. The method and system for determining condenser back pressure based on unit power and circulating water temperature of claim 1, wherein, determining the condenser back pressure according to the condenser terminal difference and the circulating water temperature rise comprises: determining the condensate temperature according to the condenser terminal difference and the circulating water temperature rise, and determining the condenser back pressure according to the saturationPressureT function and the condensate temperature.

9. A method and system for determining condenser back pressure based on unit power and circulating water temperature, characterized in that, comprise: a circulating water outlet temperature module, configured to determine the outlet temperature of the circulating water according to the condenser heat load under the current load, the measured circulating water flow of the condenser and the set constant pressure ratio heat of the unit; a circulating water density module, configured to determine the saturation pressure according to the outlet temperature of the circulating water, and determine the density of the circulating water outlet water according to the saturation pressure and the outlet temperature of the circulating water; The cooling pipe inner flow velocity module is used to determine the cooling pipe inner flow velocity of the condenser according to the condenser cooling water density, the condenser flow number set by the unit, the condenser measured circulating water flow, the condenser cooling pipe number and the condenser cooling pipe inner diameter; The heat transfer coefficient module is used to determine the total heat transfer coefficient according to the condenser cooling pipe inner flow velocity and the correction coefficient of the unit; The condenser terminal difference module is used to determine the condenser terminal difference according to the circulating water temperature rise, the total heat transfer coefficient, the condenser cooling area, the constant pressure specific heat set by the unit and the condenser measured circulating water flow; The condenser back pressure module is used to determine the condenser back pressure according to the condenser terminal difference and the circulating water temperature rise, and control the operation mode of the unit circulating pump according to the condenser back pressure.

10. An electronic device, comprising: The method comprises the following steps: a memory for storing a computer program; a processor for executing the computer program to realize the steps of the method for determining the condenser back pressure based on the unit power and the circulating water temperature according to any one of claims 1-8.

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