Method for analyzing operation performance of nuclear power feed water heater

Abstract

The invention relates to the technical field of feed water heater operation performance analysis, and provides a nuclear power feed water heater operation performance analysis method which comprises the following steps: calculating a pipe side state according to pipe side measuring point data of a feed water heater, calculating states of a feed water heater shell side and a drain outlet pipeline, and calculating heat exchange performance of a condensation zone. Comprising condensation zone heat transfer efficiency and condensation heat transfer coefficient. The operation performance and the interface thermodynamic state of the nuclear power plant feed water heater can be efficiently and accurately analyzed.

Description

Technical Field

[0001] The present invention relates to the technical field of feedwater heater operation performance analysis, and in particular to a method for analyzing the operation performance of a nuclear power feedwater heater. Background Art

[0002] The feedwater heater is an important part of the secondary circuit system. It uses the heat of the steam turbine extraction to heat the feedwater, increase the feedwater temperature, and thus improve the overall thermal efficiency of the secondary circuit. The hot medium, i.e. saturated steam, flows in from the steam extraction port, condenses into drain water through the heat transfer tube bundle in the condensation zone, and the drain water flows into the drain outlet pipeline after passing through the tube bundle in the drain cooling zone; at the same time, the cold medium, i.e. feedwater, flows into the feedwater inlet water chamber, enters each heat transfer tube to absorb heat, and finally converges and flows out in the outlet water chamber. Good heat transfer performance of the feedwater heater, i.e. thermodynamic state including feedwater temperature rise, shell side pressure and water level, is crucial to the safe and efficient operation of the system.

[0003] In recent years, with the demand for digital nuclear power and digital operation and maintenance, the development of technologies such as operation status analysis and fusion of operation data and simulation models has been promoted. The operation status analysis and data and model fusion technology for large secondary circuit equipment has become an important research. However, there are few measurement points in the unit and the lack of measurement points for important status parameters such as equipment pressure and temperature, which makes it difficult to obtain equipment operation status and performance information, and such overly simplified operation data is also difficult to use in other technical fields. Therefore, it is necessary to study the operation performance analysis method of nuclear power feedwater heaters, and to mine the thermodynamic and performance status parameters of feedwater heaters based on power plant data to support digital technologies such as operation status analysis and operation data and model fusion. Summary of the invention

[0004] The object of the present invention is to provide a method for analyzing the operating performance of a nuclear power feedwater heater, which can efficiently and accurately analyze the operating performance and interface thermodynamic state of a nuclear power plant feedwater heater.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A method for analyzing the operating performance of a nuclear power feedwater heater, comprising:

[0007] Step 1: Calculate the tube side status based on the tube side measurement point data of the feedwater heater;

[0008] Step 2: Calculate the status of the shell side and drain outlet pipeline of the feedwater heater;

[0009] Step 3: Calculate the heat transfer performance of the condensation zone, including the heat transfer efficiency of the condensation zone and the condensation heat transfer coefficient;

[0010] Step 4: Calculate the status of the steam extraction pipeline and upstream drain pipeline.

[0011] In some embodiments, step 1 specifically includes:

[0012] Step 1.1: Use the pipeline resistance model to calculate the flow value G based on the pipe side inlet and outlet pressure measurement results t :

[0013]

[0014] In the formula, a t is the pipeline conductivity value, p t,i is the inlet pressure on the tube side, p t,o is the outlet pressure on the tube side;

[0015] Step 1.2: Calculate the tube side heat transfer coefficient h using the forced convection heat transfer mechanism in the tube t :

[0016]

[0017] Where k and n are empirical heat transfer coefficients;

[0018] Step 1.3: Calculate the increment of fluid energy on the tube side based on the inlet and outlet pressure and temperature measurement results on the tube side to obtain the total heat transfer capacity Q of the heat transfer tube. st :

[0019] Q st =G t *[H(T t,o )-H(T t,i )];

[0020] In the formula, H(T t,o ) is the specific enthalpy value calculated based on the tube side outlet temperature, H(T t,i ) is the specific enthalpy calculated based on the tube side inlet temperature.

[0021] In some embodiments, step 2 specifically includes:

[0022] Step 2.1: Calculate the estimated saturation temperature of the feedwater heater and start iterative calculation;

[0023] Step 2.2: Calculate the drain outlet flow rate;

[0024] Step 2.3: Calculate the total heat transfer coefficient of the feedwater heater drain zone;

[0025] Step 2.4: Calculate the heat transfer area of ​​the feedwater heater heat transfer tube;

[0026] Step 2.5: Calculate the heat transfer of the feedwater heater drain area;

[0027] Step 2.6: Correct the feedwater heater saturation temperature.

[0028] In some embodiments, in step 2.1, the upper and lower limits Tmax and Tmin of the saturation temperature of the feed water heater are set, and the upper and lower limits Tmax and Tmin of the saturation temperature of the feed water heater are set. max and T min , set the saturation temperature convergence error η, according to Calculate the estimated saturation temperature TT of the feedwater heater sat , start iterative calculation.

[0029] In some embodiments, in step 2.2, the estimated value TT is calculated based on the saturation temperature. sat Query the saturated water and steam properties table to obtain the saturated pressure and the shell side pressure P s :

[0030] P s =f Psat (TT sat );

[0031] Where P s is the average pressure on the shell side, f Psat This is the relationship between temperature and pressure in the saturated water properties table;

[0032] The shell side pressure is superimposed on the water level pressure head to obtain the drain outlet pressure P do :

[0033] P do =P s +ρ liq *g*level;

[0034] Where P do is the pressure value at the drain outlet, ρ liq According to TT sat The liquid density value obtained by querying the saturated water property table, g is the gravity constant, and level is the measured value of the shell side water level;

[0035] The pipeline resistance model (resistance characteristics include valve characteristics) is used according to the valve position measurement results, the pressure measurement results of the downstream deaerator and condenser, and the drain outlet pressure P do Calculate the drain outlet flow value G do :

[0036]

[0037] In the formula, a do is the value of pipeline conductivity, which is calculated by pipeline structure and friction coefficient mechanism, f(vp) is valve characteristic, which is determined by valve pressure drop-flow experimental relationship curve, ΔP is feedwater heater drain outlet pressure P do The difference between the pressure measurements of the downstream deaerator and condenser.

[0038] In some embodiments, in step 2.5, the heat transfer Q of the drain area of ​​the feedwater heater is calculated based on the tube side inlet temperature and flow rate, the shell side saturation temperature and drain flow rate, the total heat transfer coefficient of the drain area, and the heat transfer area of ​​the drain area. d :

[0039] Q d =cp liq *eff*G t *(TT sat -T t,i );

[0040] Where eff is the heat transfer efficiency of the hydrophobic area, T t,i is the tube inlet temperature.

[0041] In some embodiments, in step 2.6, H do =f Hpt (P do ,T do ) Calculate the specific enthalpy value Hdo of the drain outlet,

[0042] Where, T do is the temperature measurement value on the drain outlet pipeline, f Hpt Represents the relationship between specific enthalpy, pressure and temperature in the table of physical properties of water.

[0043] According to the heat transfer Q d and drain flow G do Calculate the saturation specific enthalpy H at the feedwater heater liquid level sat , as shown below:

[0044]

[0045] According to H sat Query the saturated water properties table to obtain the saturation temperature T sat After that, the estimated saturation temperature TT sat For comparison, see:

[0046] T sat =f Tsat (H sat );

[0047] dT=T sat -TT sat ;

[0048] Where dT is the error value of the estimated temperature, f Tsat Represents the relationship between specific enthalpy and temperature in the physical properties table of saturated water.

[0049] If the error dT between the two is less than the value of η, it is considered that the saturation temperature of the feedwater heater is calculated correctly, and the iterative calculation is exited and the step 3 is entered; otherwise, the maximum saturation temperature T in step 2.1 is used. max and minimum saturation temperature T min As the estimated temperature TT sat Calculation of temperature error dTT max and dTT min ; According to dT, dTT max and dTT min Update the iteration range, i.e. T max and T min ,use Update estimated temperature TT sat After iterating again, the method for updating the iteration range is as follows:

[0050] If dT and dTT max If the signs of T max Get TT sat Value, similarly if dT and dTT min If the signs of T min Get TT sat value.

[0051] In some embodiments, step 3 specifically includes:

[0052] Step 3.1: The heat transfer Q of the hydrophobic area calculated in step S2 d and pipe side flow G t , calculate the outlet temperature of the drain zone tube side, and obtain the inlet temperature T of the condensation zone tube side ti,con :

[0053]

[0054] Step 3.2: The total heat transfer Q of the heat transfer tube calculated according to step 1 t Subtract the heat transfer Q of the hydrophobic area calculated in step 2 d Get the total heat transfer Q of the heat transfer tube in the condensation zone con ;

[0055] Step 3.3: Calculate the heat transfer efficiency Eff in the condensation zone con and condensation heat transfer coefficient h con ,as follows:

[0056]

[0057] In the formula, Q con is the heat transfer in the condensation zone, Tsat is the saturation temperature, A con is the heat transfer area, T ti,con is the inlet temperature of the tube side of the condensation zone, G t is the tube side flow rate, hw is the heat transfer coefficient of the tube wall, h d is the total heat transfer coefficient of the feedwater heater drain area, h t is the tube side convective heat transfer coefficient, h s is the total heat transfer coefficient of shell-side steam and tube-side feed water.

[0058] In some embodiments, in step 4, the drain outlet pressure is calculated according to the pressure and water level measurement results; the drain specific enthalpy is calculated by querying the water and steam physical property table using the drain outlet pressure calculation result and the temperature measurement result; the drain flow is calculated according to the valve position and pressure value using the pipeline resistance model. Step 4 is to calculate the thermodynamic state of the shell side inflow interface, that is, the specific enthalpy and flow value.

[0059] In some embodiments, in step 4, the saturated water physical property table is queried according to the hydrophobic temperature measurement result to obtain the estimated value of the hydrophobic pressure and the estimated value of the specific enthalpy; and the pipeline resistance model is used to calculate the hydrophobic flow value according to the pressure and valve position.

[0060] Compared with the prior art, the nuclear power feedwater heater operation performance analysis method provided by the present invention has the following beneficial effects:

[0061] The present invention realizes the function of calculating the thermodynamic and performance status parameters of the feedwater heater based on the power plant data, thereby meeting the data requirements of digital technologies such as operation status analysis, operation data and model fusion, etc.

[0062] The present invention can efficiently and accurately analyze the operating performance and interface thermodynamic state of the feedwater heater of a nuclear power plant. The operating performance includes the heat transfer efficiency and heat transfer coefficient of the feedwater heater. The interface thermodynamic state includes the flow rate and specific enthalpy value of the feedwater side inlet and outlet, the shell side drain inlet and outlet, and the shell side steam extraction inlet.

[0063] Based on limited unit measurement data, the present invention can cleverly use the high-reliability and high-precision mechanism model to find the correct thermodynamic state of the feedwater heater through estimation and correction, thereby realizing the mining of the feedwater heater's operating performance and providing key data support for technologies such as operating status analysis and data fusion models. The performance analysis results of a feedwater heater based on full-range simulator data show that this method has good calculation accuracy, and the relative error of the calculated heat exchange performance, tube-side flow and other related thermal hydraulic parameters is within 1%.

[0064] There are few measurement points in the feedwater heater of a nuclear power plant, and the lack of measurement of the thermodynamic state of the equipment itself, such as pressure and temperature, not only makes it difficult to monitor the operating status of the equipment, but also limits the application of operating data in the fields of artificial intelligence model development and simulation model optimization. This method establishes a mapping relationship from a small number of measurement values ​​to the detailed operating performance of the equipment, enriching the dimension of operating information, which can not only be used to monitor the operating status of the feedwater heater, but also support the development of artificial intelligence models and optimization simulation models and other applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for the technical description.

[0066] Figure 1 A flow chart of a method for analyzing the operating performance of a nuclear power feedwater heater provided by the present invention;

[0067] Figure 2 A schematic diagram of the arrangement of measuring points for the feedwater heater provided by the present invention;

[0068] Figure 3 The condensation heat exchange efficiency calculation error change curve provided by the present invention, wherein the horizontal axis is the sample point number;

[0069] Figure 4 This is a curve of the error variation in flow calculation of the drain outlet pipeline provided by the present invention, wherein the horizontal axis is the sample point number. DETAILED DESCRIPTION

[0070] The following is further explained in detail through specific implementation methods.

[0071] like Figure 1 As shown, the present invention provides a method for analyzing the operating performance of a nuclear power feedwater heater. First, the total heat transfer amount is calculated based on the measurement results on the tube side. Then, the upper and lower limits of the shell side temperature are estimated and iterative correction calculations are performed using the heat exchange mechanism of the hydrophobic area to obtain thermodynamic state parameters such as the shell side temperature. Finally, based on the thermodynamic state of the shell side, the heat transfer performance of the feedwater heater and the thermodynamic state of each pipeline are further calculated.

[0072] The present invention can efficiently and accurately analyze the operating performance and interface thermodynamic state of a nuclear power plant feedwater heater, and calculate respectively: tube side state; shell side drain outlet state; equipment performance and state; upstream interface state, including steam extraction, upstream feedwater heater drain and upstream drain tank drain.

[0073] The method specifically comprises the following steps:

[0074] Step 1: Calculate the status of the tube side according to the data of the tube side measuring points of the feedwater heater. Usually, the inlet and outlet pipelines of the feedwater heater are equipped with pressure and temperature measuring points. The specific calculation process is as follows:

[0075] Step 1.1: Use the existing pipeline resistance model to calculate the flow value G based on the pipe side inlet and outlet pressure measurement results t .

[0076] Step 1.2: Calculate the tube side heat transfer coefficient h using the existing flow heat transfer mechanism in the tube t .

[0077] Step 1.3: Calculate the increment of fluid energy on the tube side according to the measured results of the inlet and outlet pressure and temperature on the tube side, which is the total heat transfer capacity Q of the heat transfer tube. st The fluid energy is characterized by the specific enthalpy value obtained by consulting the water and steam property table based on pressure and temperature.

[0078] Step 2: Calculate the status of the feedwater heater shell side and the drain outlet pipeline. Usually, the feedwater heater shell side includes the drain outlet temperature and water level measurement points, and the drain outlet pipeline includes the drain valve position, drain outlet temperature and downstream equipment status measurement sensors, among which the downstream equipment status sensors are divided into temperature and pressure sensors. The details are as follows:

[0079] Step 2.1: Set the upper and lower limits of the saturation temperature of the feedwater heater T max and T min , set the saturation temperature convergence error η, according to the formula (T max +T min ) / 2Calculate the estimated saturation temperature TT of the feedwater heater sat , start iterative calculation.

[0080] Step 2.2: Calculate the drain outlet flow rate G do .

[0081] Estimated TT based on saturation temperature sat The saturated pressure obtained by querying the saturated water and steam properties table is the shell side pressure P s The shell side pressure plus the water level pressure head can be obtained by adding the drain outlet pressure P do The pipeline resistance model is used according to the valve position measurement results, downstream equipment pressure measurement results and drain outlet pressure P do Calculate the drain outlet flow value G do When the downstream equipment status only has a temperature sensor, the saturated water and steam physical property table can be queried to obtain the saturated pressure value for calculation.

[0082] Step 2.3: Calculate the total heat transfer coefficient of the feedwater heater drain area.

[0083] The total heat transfer coefficient of the drain zone is determined by the tube side convective heat transfer coefficient h t , tube wall heat transfer coefficient h w and shell side convection heat transfer coefficient h sdComposition. The heat transfer coefficient of the tube wall h w It can be calculated based on the pipe wall thickness and thermal conductivity. sd It is calculated based on the heat transfer mechanism of single-phase fluid across the tube bundle.

[0084] Step 2.4: Calculate the heat exchange area of ​​the feedwater heater heat transfer tube. The heat exchange area of ​​the nuclear power feedwater heater heat transfer tube can usually be divided into a condensation heat exchange area and a hydrophobic heat exchange area according to the different heat exchange modes. The hydrophobic heat exchange area corresponds to the area of ​​the heat transfer tube submerged by the hydrophobic zone. The heat exchange area of ​​the hydrophobic zone and the condensation zone can be calculated based on the water level measurement results and the layout height of the feedwater heater heat transfer tube.

[0085] Step 2.5: Calculate the heat transfer Q of the feedwater heater drain area d .Q d The heat transfer efficiency method can be used to calculate the heat transfer efficiency based on the tube side inlet temperature and flow rate, shell side saturation temperature and drain flow rate, total heat transfer coefficient of the drain zone, and heat transfer area of ​​the drain zone.

[0086] Step 2.6: Correct the feedwater heater saturation temperature T sat .

[0087] First, according to the measured results of the drain outlet temperature and the drain pressure P in step 2.2 do Query the water and steam properties table to calculate the drain outlet specific enthalpy value H do .

[0088] Then, the energy conservation principle is combined with the heat transfer Q in step 2.5. d and the hydrophobic flow rate G in step 2.2 do Calculate the saturation specific enthalpy H at the feedwater heater liquid level sat According to H sat Query the saturated water properties table to obtain the saturation temperature T sat Then, the saturation temperature TT estimated in step 2.1 is sat Compare and calculate the correction error dT = T sat -TT sat If the error between the two is less than the value of η, it is considered that the saturation temperature of the feedwater heater is calculated correctly, and the iterative calculation is exited and the step 3 is entered. Otherwise, the maximum saturation temperature T in step 2.1 is used respectively. max and minimum saturation temperature T min As the estimated temperature TT sat Calculate the temperature error dT Tmax and dT Tmin .

[0089] Finally update the upper and lower limits of the saturated temperature of the feedwater heater T max and T min Then return to step 2.1 and restart the iterative calculation. During the update process, if dTTmax If the same number is used, TT is used. sat Replace T max Similarly, if dT and dT Tmin If the same number is used, TT is used. sat Replace T min .

[0090] Step 3: Calculate the heat transfer performance of the condensation zone. The specific calculation process is as follows:

[0091] Step 3.1: Calculate the inlet temperature T of the heat transfer tube in the condensation zone ti,con .

[0092] The heat transfer Q of the hydrophobic area calculated according to step 2 using the principle of energy conservation d And the tube side inlet specific enthalpy and tube side flow rate G calculated in step 1 t , calculate the outlet temperature of the drain zone tube side, that is, the inlet temperature of the condensation zone tube side T ti,con .

[0093] Step 3.2: Calculate the total heat transfer Q of the heat transfer tube in the condensation zone con The total heat transfer amount Q of the heat transfer tube calculated according to step 1 t Subtract the heat transfer Q of the hydrophobic area calculated in step 2 d get.

[0094] Step 3.3: Calculate the heat transfer efficiency Eff in the condensation zone con and condensation heat transfer coefficient h con .

[0095] The heat transfer efficiency method is used to calculate the heat transfer Q in the condensation zone. con , saturation temperature T sat , heat exchange area, condensation zone tube side inlet temperature T ti,con , pipe side flow G t Calculate Eff con and h con .

[0096] Step 4: Calculate the status of the steam extraction pipeline and the upstream drain pipeline. The steam extraction pipeline and the upstream drain pipeline include: the steam extraction pipeline (inflow), the drain pipeline of the upstream drain tank (inflow), and the drain pipeline of the upstream feedwater heater (inflow).

[0097] (1) Usually, the steam extraction pipeline has pressure and temperature sensors, and the temperature sensor has higher reliability and accuracy. The temperature measurement result is used to query the saturated steam property table to obtain the pressure value. The steam extraction pipeline resistance model is used to calculate the steam extraction flow value based on the extraction pressure calculation result and the saturated pressure of the feedwater heater.

[0098] (2) Usually, the drain pipeline of the upper drain tank is equipped with a valve position sensor, and the upper drain tank is equipped with pressure, temperature and water level sensors. First, the drain outlet pressure is calculated based on the pressure and water level measurement results. Then, the water and steam physical properties table is used to calculate the drain specific enthalpy using the drain outlet pressure calculation results and temperature measurement results. Finally, the pipeline resistance model is used to calculate the drain flow rate based on the valve position and pressure values.

[0099] (3) Usually, valve position and drain temperature sensors are installed in the drain pipeline of the upstream feedwater heater. First, the saturated water physical property table is queried according to the drain temperature measurement result to obtain the estimated value of the drain pressure and specific enthalpy, and then the pipeline resistance model is used to calculate the drain flow value according to the pressure and valve position.

[0100] Example

[0101] like Figures 2 to 4 As shown, the following takes a PWR 6 high-pressure feedwater heater as an example to illustrate the specific implementation process of the present invention. The relevant measurement points of the feedwater heater are arranged as follows: Figure 2 The meaning of each measuring point number is shown in Table 1 below:

[0102] Table 1 Summary of measurement points of No. 6 high pressure feedwater heater

[0103]

[0104]

[0105] Step 1: Calculate the tube side status based on the tube side measurement point data of the feedwater heater. The details are as follows:

[0106] Step 1.1: Use the following pipeline resistance model to calculate the flow value G based on the pipe side inlet and outlet pressure measurement results t The formula is as follows:

[0107]

[0108] Among them, a t is the value of pipeline conductivity, which is calculated based on the pipeline structure and friction coefficient mechanism; p t,i is the inlet pressure on the tube side; p t,o is the pipe side outlet pressure.

[0109] Step 1.2: Calculate the tube side heat transfer coefficient h using the DB formula t The formula is as follows:

[0110]

[0111] Among them, k and n are empirical heat transfer coefficients.

[0112] Step 1.3: Based on the principle of energy conservation, use the following formula to calculate the enthalpy rise of the fluid on the tube side, that is, the total heat transfer capacity of the heat transfer tube Q st The formula is as follows:

[0113] Q st =G t *[H(T t,o )-H(T t,i )]

[0114] Among them, H(T t,o ) is the specific enthalpy value calculated based on the tube side outlet temperature; H(T t,i ) is the specific enthalpy calculated based on the tube side inlet temperature.

[0115] Step 2: Calculate the status of the feedwater heater shell side and drain outlet pipeline. The details are as follows:

[0116] Step 2.1: Set the upper and lower limits of the saturation temperature of the feedwater heater T max = Drain outlet temperature measurement result + 100 and T min =Drain outlet temperature measurement result + 0.01, set the saturation temperature convergence error η = 1.0e-8.

[0117] Calculate the estimated saturation temperature TT of the feedwater heater according to the following formula sat Then, the iterative calculation begins.

[0118]

[0119] Step 2.2: Calculate the drain outlet flow rate G do .

[0120] According to the saturation temperature T sat The saturated pressure obtained by querying the saturated water and steam properties table is the shell side pressure Ps:

[0121] P s =f Psat (TT sat )

[0122] Among them, f Psat Represents the relationship between temperature and pressure in the table of physical properties of saturated water;

[0123] The shell side pressure is superimposed on the water level pressure head to obtain the drain outlet pressure P do :

[0124] P do =P s +ρ liq *g*level

[0125] The pipeline resistance model is used to calculate the pressure of the downstream deaerator and condenser according to the valve position measurement results, the pressure measurement results of the downstream deaerator and condenser, and the drain outlet pressure P do Calculate the drain outlet flow value G do .

[0126] The pipeline resistance model with valve is as follows:

[0127]

[0128] Among them, a do is the value of the pipeline conductivity coefficient, which is calculated by the pipeline structure and friction coefficient mechanism. f(vp) is the valve characteristic, which is determined by the valve pressure drop-flow experimental relationship curve; ΔP is the feedwater heater drain outlet pressure P do The difference between the pressure of the downstream deaerator and condenser.

[0129] Step 2.3: Calculate the total heat transfer coefficient h of the feedwater heater drain area d The total heat transfer coefficient of the hydrophobic zone is determined by the tube side convective heat transfer coefficient h t , tube wall heat transfer coefficient h w and shell side convection heat transfer coefficient h sd composition:

[0130]

[0131] Among them, the heat transfer coefficient of the tube wall h w It can be calculated based on the tube wall thickness and thermal conductivity. λ is the thermal conductivity of the tube wall, and k is the tube wall thickness. sd It is calculated according to the Rocard relationship.

[0132] Step 2.4: Calculate the heat transfer area of ​​the feedwater heater heat transfer tube.

[0133] Calculate the heat exchange area A of the drain zone based on the water level measurement results and the layout height of the heat transfer tubes of the feedwater heater. d and the heat exchange area A of the condensation zone con .

[0134] Step 2.5: Calculate the heat transfer Q of the feedwater heater drain area d .

[0135] The heat transfer efficiency method is used to calculate the heat transfer efficiency based on the tube side inlet temperature and flow rate, shell side saturation temperature and drain flow rate, drain area total heat transfer coefficient, and drain area heat transfer area. The heat transfer calculation formula is as follows, where eff is the heat transfer efficiency, which is calculated by the heat transfer efficiency method.

[0136] Q d =cp liq *eff*G t *(TT sat -Tt,i )

[0137] Step 2.6: Correct the feedwater heater saturation temperature Tsat.

[0138] First, according to the drain outlet temperature measurement result T do and the hydrophobic pressure P in step 2.2 do Query the water and steam properties table to calculate the drain outlet specific enthalpy value H do .

[0139] H do =f Hpt (P do ,T do )

[0140] Then, the energy conservation principle is combined with the heat transfer Q in step 2.5. d and the hydrophobic flow rate G in step 2.2 do Calculate the saturation specific enthalpy H at the feedwater heater liquid level sat , the details are as follows:

[0141]

[0142] Finally, according to H sat Query the saturated water properties table to obtain the saturation temperature T sat Then, the saturation temperature TT estimated in step 2.1 is sat for comparison.

[0143] T sat =f Tsat (H sat )

[0144] dT=T sat -TT sat

[0145] (1) If the error dT between the two is less than the value of η, it is considered that the saturation temperature of the feedwater heater is calculated correctly, and the iterative calculation is exited and the process goes to step 3.

[0146] (2) Otherwise, use the maximum saturation temperature T in step 2.1 respectively max and minimum saturation temperature T min As the estimated temperature TT sat Calculate the respective estimation error dT Tmax and dT Tmin Finally update the upper and lower limits of the saturated temperature of the feedwater heater T max and T min Then return to step 2.1 and restart the iterative calculation. During the update process, if dT and dT Tmax If the same number is used, TT is used. sat Replace T maxSimilarly, if dT and dT Tmin If the same number is used, TT is used. sat Replace T min .

[0147] Step 3: Calculate the heat transfer performance of the condensation zone. The details are as follows:

[0148] Step 3.1: Calculate the inlet temperature T of the heat transfer tube in the condensation zone ti,con .

[0149] The heat transfer Q of the hydrophobic area calculated according to step S2 using the energy conservation principle d and pipe side flow G t , calculate the outlet temperature of the drain zone tube side, that is, the inlet temperature of the condensation zone tube side T ti,con .

[0150]

[0151] Step 3.2: Calculate the total heat transfer Q of the heat transfer tube in the condensation zone con .

[0152] The total heat transfer Q of the heat transfer tube calculated according to step 1 t Subtract the heat transfer Q of the hydrophobic area calculated in step 2 d get.

[0153] Q con =Q t -Q d

[0154] Step 3.3: Calculate the heat transfer efficiency Eff in the condensation zone con and condensation heat transfer coefficient h con .

[0155] The heat transfer efficiency method is used to calculate the heat transfer Q in the condensation zone. con , saturation temperature T sat , heat exchange area A con , condensation zone tube side inlet temperature T ti,con , pipe side flow G t Calculate Eff con and h con ,as follows:

[0156]

[0157] Step 4: Calculate the status of the steam extraction pipeline and upstream drain pipeline.

[0158] (1) The temperature measurement result is used to query the saturated steam property table to obtain the pressure value, and the extraction steam flow value is calculated based on the extraction steam pressure calculation result and the saturated pressure of the feedwater heater using the extraction steam line resistance model.

[0159] (2) Calculate the status of the upstream drain tank drain pipeline. First, calculate the drain outlet pressure based on the pressure and water level measurement results. Then, use the drain outlet pressure calculation results and temperature measurement results to query the water and steam physical property table to calculate the drain specific enthalpy. Finally, use the pipeline resistance model to calculate the drain flow rate based on the valve position, drain tank drain outlet pressure value and feedwater heater saturation pressure.

[0160] (3) Calculate the status of the No. 7 high-pressure feedwater heater drain pipeline. Similarly, first query the saturated water physical property table based on the drain temperature measurement results to obtain the estimated drain pressure and specific enthalpy values, and then use the pipeline resistance model to calculate the drain flow value based on the pressure and valve position.

[0161] In order to verify the calculation effect of this method, a full-range simulator of a nuclear power plant was used to generate simulation data, and the simulation data was used as the measurement point and operation performance sample library of No. 6 high-pressure feedwater heater. This method was used to process the measurement point data in the sample library, and the calculation results were compared with the operating performance reference values. The relative error change curve is shown in Figure 2. Figure 3 and Figure 4 As shown, the relative errors in the curves are much less than 1%, indicating that this method has good calculation accuracy.

[0162] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for analyzing the operating performance of a nuclear power feedwater heater, characterized in that: include: Step 1: Calculate the tube side status based on the tube side measurement point data of the feedwater heater; Step 2: Calculate the status of the shell side and drain outlet pipeline of the feedwater heater; Step 3: Calculate the heat transfer performance of the condensation zone, including the heat transfer efficiency of the condensation zone and the condensation heat transfer coefficient; Step 4: Calculate the status of the steam extraction pipeline and upstream drain pipeline.

2. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 1, characterized in that: Step 1 specifically includes: Step 1.1: Use the pipeline resistance model to calculate the flow value G based on the pipe side inlet and outlet pressure measurement results t : In the formula, a t is the pipeline conductivity value, p t,i is the measured value of the inlet pressure on the tube side, p t,o is the measured value of the outlet pressure on the tube side; Step 1.2: Calculate the tube side heat transfer coefficient h using the forced convection heat transfer mechanism in the tube t : Where k and n are empirical heat transfer coefficients; Step 1.3: Calculate the increment of fluid energy on the tube side based on the inlet and outlet pressure and temperature measurement results on the tube side to obtain the total heat transfer capacity Q of the heat transfer tube. st : Q st =G t *[H(T t,o )-H(T t,i )]; In the formula, H(T t,o ) is the measured value of the tube side outlet temperature T t,o The calculated specific enthalpy, H(T t,i ) is the measured value of the tube side inlet temperature T t,i Calculate the specific enthalpy.

3. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 1, characterized in that: Step 2 specifically includes: Step 2.1: Calculate the estimated saturation temperature of the feedwater heater and start iterative calculation; Step 2.2: Calculate the drain outlet flow rate; Step 2.3: Calculate the total heat transfer coefficient of the feedwater heater drain zone; Step 2.4: Calculate the heat transfer area of ​​the feedwater heater heat transfer tube; Step 2.5: Calculate the heat transfer of the feedwater heater drain area; Step 2.6: Correct the feedwater heater saturation temperature.

4. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 3, characterized in that: In step 2.1, set the upper and lower limits of the saturated temperature of the feedwater heater T max and T min , set the saturation temperature convergence error η, according to Calculate the estimated saturation temperature TT of the feedwater heater sat , start iterative calculation.

5. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 3, characterized in that: In step 2.2, estimate TT based on the saturation temperature sat Query the saturated water and steam properties table to obtain the saturated pressure and the shell side pressure P s : P s =f Psat (TT sat ); Where P s is the average pressure on the shell side, f Psat This is the relationship between temperature and pressure in the saturated water properties table; The shell side pressure is superimposed on the water level pressure head to obtain the drain outlet pressure P do : P do =P s +ρ liq *g*level; Where P do is the pressure value at the drain outlet, ρ liq According to TT sat The liquid density value obtained by querying the saturated water property table, g is the gravity constant, and level is the measured value of the shell side water level; The pipeline resistance model is used to calculate the pressure of the downstream deaerator and condenser according to the valve position measurement results, the pressure measurement results of the downstream deaerator and condenser, and the drain outlet pressure P do Calculate the drain outlet flow value G do : In the formula, a do is the value of pipeline conductivity, which is calculated by pipeline structure and friction coefficient mechanism, f(vp) is valve characteristic, which is determined by valve pressure drop-flow experimental relationship curve, ΔP is feedwater heater drain outlet pressure P do The difference between the pressure measurements of the downstream deaerator and condenser.

6. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 3, characterized in that: In step 2.5, according to the measured value of the tube side inlet temperature T t,i and flow G t , shell side saturation temperature estimate TT sat The heat transfer efficiency of the drain zone is calculated to obtain the heat transfer Q of the drain zone of the feedwater heater. d : Q d =cp liq *eff*G t *(TT sat -T t,i ); Where eff is the heat transfer efficiency of the hydrophobic zone, which is calculated based on the unit efficiency method from the hydrophobic flow rate, the total heat transfer coefficient of the hydrophobic zone, and the heat transfer area of ​​the hydrophobic zone. liq is the specific heat value of liquid phase at constant pressure, T t,i is the tube inlet temperature.

7. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 3 or 4, characterized in that: In step 2.6, H do =f Hpt (P do ,T do ) Calculate the specific enthalpy value H at the drain outlet do ; Where, T do is the temperature measurement value on the drain outlet pipeline, f Hpt Represents the relationship between specific enthalpy and pressure and temperature in the table of physical properties of water; According to the heat transfer Q d and drain flow G do Calculate the saturation specific enthalpy H at the feedwater heater liquid level sat , as shown below: According to H sat Query the saturated water properties table to obtain the saturation temperature T sat After that, the estimated saturation temperature TT sat For comparison, the formula is as follows: T sat =f Tsat (H sat ); dT=T sat -TT sat ; Where dT is the error value of the estimated temperature, f Tsat Represents the relationship between specific enthalpy and temperature in the table of physical properties of saturated water; If the error dT between the two is less than the value of η, it is considered that the saturation temperature of the feedwater heater is calculated correctly, and the iterative calculation is exited and the step 3 is entered; otherwise, the maximum saturation temperature T in step 2.1 is used. max and minimum saturation temperature T min As the estimated temperature TT sat Calculation of temperature error dTT max and dTT min ; According to dT, dTT max and dTT min Update the iteration range, i.e. T max and T min ,use Update estimated temperature TT sat After iterating again, the method for updating the iteration range is as follows: If dT and dTT max If the signs of T max Get TT sat Value, similarly if dT and dTT min If the signs of T min Get TT sat value.

8. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 1, characterized in that: Step 3 specifically includes: Step 3.1: The heat transfer Q of the hydrophobic area calculated in step S2 d and pipe side flow G t , calculate the outlet temperature of the drain zone tube side, and obtain the inlet temperature T of the condensation zone tube side ti,con : Step 3.2: The total heat transfer Q of the heat transfer tube calculated according to step 1 t Subtract the heat transfer Q of the hydrophobic area calculated in step 2 d Get the total heat transfer Q of the heat transfer tube in the condensation zone con ; Step 3.3: Calculate the heat transfer efficiency Eff in the condensation zone con and condensation heat transfer coefficient h con ,as follows: In the formula, Q con is the heat transfer in the condensation zone, Tsat is the saturation temperature, A con is the heat transfer area, T ti,con is the inlet temperature of the tube side of the condensation zone, G t is the tube side flow rate, h w is the heat transfer coefficient of the tube wall, h d is the total heat transfer coefficient of the feedwater heater drain area, h t is the tube side convective heat transfer coefficient, h s is the total heat transfer coefficient of shell-side steam and tube-side feed water.

9. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 1, characterized in that: In step 4, the drain outlet pressure is calculated based on the pressure and water level measurement results; the drain specific enthalpy is calculated by querying the water and steam physical property table using the drain outlet pressure calculation result and the temperature measurement result; and the drain flow is calculated based on the valve position and pressure value using the pipeline resistance model.

10. The method for analyzing the operating performance of a nuclear power feedwater heater according to claim 1, characterized in that: In step 4, the saturated water physical property table is queried according to the measurement result of the drain temperature to obtain the estimated value of the drain pressure and the estimated value of the specific enthalpy; the pipeline resistance model is used to calculate the drain flow value according to the pressure and valve position.

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