A method for analyzing the operation performance of a nuclear power water feeder heater

Abstract

The present application relates to the technical field of water heater operation performance analysis, and provides a nuclear power water heater operation performance analysis method, which calculates the tube side state according to the tube side measuring point data of the water heater, calculates the shell side and the drain outlet pipeline state of the water heater, calculates the condensation zone heat exchange performance, including the condensation zone heat transfer efficiency and the condensation heat exchange coefficient, and calculates the extraction pipeline and the upper drain pipeline state. The present application can efficiently and accurately analyze the operation performance and interface thermodynamic state of the nuclear power plant water heater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water heater operation performance analysis, and particularly relates to a nuclear power water heater operation performance analysis method. BACKGROUND

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

[0003] In recent years, with the proposal of digital nuclear power and digital operation and maintenance requirements, the development of operation state analysis, operation data and simulation model fusion technologies has been promoted. The operation state analysis, data and model fusion technology for large-scale equipment in the secondary circuit has become an important research. However, the unit has fewer measuring points and lacks important state parameters such as equipment pressure and temperature measuring points, making it difficult to obtain the equipment operation state and performance information, and such overly brief operation data is also difficult to use in other technical fields. Therefore, it is necessary to study the nuclear power water heater operation performance analysis method, to mine the thermodynamic and performance state parameters of the water heater based on the power plant data to support the operation state analysis, operation data and model fusion digital technologies. SUMMARY

[0004] The present application aims to provide a nuclear power water heater operation performance analysis method, which can efficiently and accurately analyze the operation performance and interface thermodynamic state of the water heater in the nuclear power plant.

[0005] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A nuclear power water heater operation performance analysis method, comprising:

[0007] Step 1: calculating the tube side state according to the tube side measuring point data of the water heater;

[0008] Step 2: calculating the shell side and drain outlet pipeline state of the water heater;

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

[0010] Step 4: calculating the extraction pipeline and upper drain pipeline state.

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

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

[0013]

[0014] Where a t is the pipeline conductivity coefficient, 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 inside 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 measured pressure and temperature on the tube side, and 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] Where, 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 area;

[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 drain area of ​​the feedwater heater;

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

[0028] In some embodiments, in step 2.1, the upper and lower limits of the saturation temperature of the feedwater heater, Tmaxand Tmin, are set, and the upper and lower limits of the saturation temperature of the feedwater heater, Tmaxand Tmin, are set max and T min , the saturation temperature convergence error η is set, and the saturation temperature estimate TT sat of the feedwater heater is calculated according to , and the iterative calculation is started.

[0029] In some embodiments, in step 2.2, the saturation pressure is obtained by querying the saturated water and steam property table according to the saturation temperature estimate TT sat , and the shell side pressure P s is obtained:

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

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

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

[0033] P do = P s + ρ liq *g*level;

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

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

[0036]

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

[0038] In some embodiments, in step 2.5, the heat exchange amount Q of the water heater's water side is calculated according to the water side inlet temperature and flow rate, the shell side saturation temperature and the water flow rate, the total heat exchange coefficient of the water side, and the water side heat exchange area. d :

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

[0040] In the formula, eff is the heat exchange efficiency of the water side, and T t,i is the water side inlet temperature.

[0041] In some embodiments, in step 2.6, the water outlet specific enthalpy Hdo is calculated by H do = f Hpt (P do , T do );

[0042] In the formula, T do is the temperature measurement on the water outlet pipeline, and f Hpt represents the relationship between the specific enthalpy and the pressure and temperature in the water property table.

[0043] The saturation specific enthalpy H d at the liquid level of the water heater is calculated according to the heat exchange amount Q do and the water flow rate G sat , as shown in the following formula:

[0044]

[0045] The saturation temperature T sat is obtained by querying the saturated water property table according to H sat , and is compared with the estimated saturation temperature TT sat , as follows:

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

[0047] dT = T sat -TT sat ;

[0048] In the formula, dT is the error value of the estimated temperature, and f Tsat represents the relationship between the specific enthalpy and the temperature in the saturated water property table.

[0049] If the error dT between the two is less than the value of η, the saturation temperature of the feedwater heater is considered to be calculated correctly, and the iterative calculation is exited and the process is entered into step 3; 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 Calculate the temperature error dTT max and dTT min ; According to dT, dTT max and dTT min Update iteration range, i.e. T max and T min ,use Update estimated temperature TT sat After iterating again, the update iteration range method is as follows:

[0050] If dT and dTT max If the signs of T are consistent max Get TT sat Value, similarly if dT and dTT min If the signs of T are consistent 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 hydrophobic 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] Where 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 htube is the tube wall heat transfer coefficient d h is the total heat transfer coefficient of the drain area of the feedwater heater t htube is the tube side convective heat transfer coefficient s htot is the total heat transfer coefficient of the steam on the shell side and the feedwater on the tube side.

[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 property table with the drain outlet pressure calculation result and the temperature measurement result; and the drain flow rate is calculated according to the valve position and the pressure value by using a pipe resistance model. Step 4 is to calculate the thermodynamic state of the shell side inflow interface, i.e., the specific enthalpy and the flow rate value.

[0059] In some embodiments, in step 4, the drain pressure estimation value and the specific enthalpy estimation value are obtained by querying the saturated water property table according to the drain temperature measurement result; and the drain flow rate value is calculated according to the pressure and the valve position by using a pipe resistance model.

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

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

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

[0063] The application can find the correct thermodynamic state of the feedwater heater by pre-estimation correction based on limited unit measurement data, skillfully use high-reliability and high-precision mechanism models, realize the mining of the operation performance of the feedwater heater, and provide key data support for technologies such as operation state analysis and data fusion models. The performance analysis results of a certain feedwater heater based on full-range simulation machine data show that the method has good calculation accuracy, and the relative errors of the heat exchange performance, the tube side flow rate and other related thermal hydraulic parameters obtained by calculation are within 1%.

[0064] The measurement points of the feedwater heater of the nuclear power plant are less, and the measurement of the thermodynamic state such as pressure and temperature of the equipment itself is lacking, which not only leads to difficulty in monitoring the running state of the equipment, but also limits the application of the running data in the development of artificial intelligence models and the optimization of simulation models. The method establishes a mapping relationship from a small amount of measurement values to the detailed running performance of the equipment, enriches the dimension of the running information, and can not only be used for monitoring the running state of the feedwater heater, but also can support the development of artificial intelligence models and the optimization of simulation models and other applications. BRIEF DESCRIPTION OF DRAWINGS

[0065] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the technical description.

[0066] Figure 1 The flow chart of the nuclear power feedwater heater running performance analysis method provided by the present application;

[0067] Figure 2 The feedwater heater measurement point arrangement schematic diagram provided by the present application;

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

[0069] Figure 4 The steam outlet pipeline flow calculation error change curve provided by the present application, wherein the horizontal axis is the sample point number. DETAILED DESCRIPTION

[0070] The following will be further described in detail through specific embodiments.

[0071] As shown in the Figure 1 The present application provides a nuclear power feedwater heater running performance analysis method, which first calculates the total heat transfer amount according to the tube side measurement results, then calculates the shell side temperature and other thermodynamic state parameters through iterative correction calculation by estimating the upper and lower limit ranges of the shell side temperature and using the steam zone heat transfer mechanism, and finally further calculates the feedwater heater heat transfer performance and the thermodynamic state of each pipeline based on the shell side thermodynamic state.

[0072] The present application can efficiently and accurately analyze the running performance and interface thermodynamic state of the feedwater heater of the nuclear power plant, and calculate the tube side state, the shell side steam outlet state, the equipment itself performance and state, and the upstream interface state including steam extraction, upstream feedwater heater steam and upstream steam tank steam.

[0073] The method specifically includes the following steps:

[0074] Step 1: According to the tube side measurement point data of the feedwater heater, the tube side state is calculated. The inlet and outlet pipelines of the tube side of the feedwater heater are usually provided with pressure and temperature measurement points, and the specific calculation process is as follows:

[0075] Step 1.1: Calculate the flow rate G using the existing pipe resistance model according to the inlet and outlet pressure measurements of the tube side t .

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

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

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

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

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

[0081] According to the estimated value TT sat of the saturation temperature, query the saturated water and steam property table to obtain the saturation pressure, which is the shell side pressure P s . The shell side pressure plus the water level reposition pressure head can obtain the drain outlet pressure P do . The drain outlet flow rate value G do is calculated using the pipe resistance model according to the valve position measurement result, the downstream equipment pressure measurement result, and the drain outlet pressure P do . When the downstream equipment state only has a temperature sensor, the saturation pressure value obtained by querying the saturated water and steam property table can be used for calculation.

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

[0083] The total heat transfer coefficient of the drain area is composed of the tube side convective heat transfer coefficient h t , the tube wall heat transfer coefficient h w , and the shell side convective heat transfer coefficient h sdComposition. Where the tube wall heat transfer coefficient h w Can be calculated according to the tube wall thickness and thermal conductivity. sd Then according to the single-phase fluid across the tube bundle heat transfer mechanism is calculated.

[0084] Step 2.4: Calculate the feedwater heater heat transfer pipe heat transfer area. The nuclear power feedwater heater heat transfer pipe heat transfer area is usually divided into condensation heat transfer area and drain heat transfer area according to the different heat transfer modes. Among them, the drain heat transfer area corresponds to the heat transfer pipe area submerged by the drain, which can be calculated according to the water level measurement results and the feedwater heater heat transfer pipe arrangement height to calculate the heat transfer area of the drain area and the condensation area.

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

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

[0087] First, according to the drain outlet temperature measurement results and the drain pressure P do of step 2.2, the drain outlet specific enthalpy H do is calculated by querying the water and steam property table.

[0088] Then, according to the energy conservation principle, combined with the heat transfer quantity Q d of step 2.5 and the drain flow G do of step 2.2, the saturation specific enthalpy H sat at the liquid level of the feedwater heater is calculated. According to H sat , the saturation temperature T sat is obtained by querying the saturated water property table. Then, compared with the pre-estimated saturation temperature TT sat of step 2.1, the correction error dT = T sat -TT sat is calculated. If the error is less than η value, it is considered that the saturation temperature calculation of the feedwater heater is correct, and the iteration calculation is exited to enter step 3. Otherwise, the maximum saturation temperature T max and the minimum saturation temperature T min in step 2.1 are used as the pre-estimated temperature TT sat to calculate the temperature error dT Tmax and dT Tmin .

[0089] Finally, update the upper and lower limit values T max and T min of the saturation temperature of the feedwater heater, and return to step 2.1 to start the iteration calculation again. If dT and dTTmax If the same, then use TT sat Replace T max , and for the same reason if dT and dT Tmin are the same, then use TT 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 ti,con of the condensation zone heat transfer tube.

[0092] According to the energy conservation principle, the heat transfer Q d of the drain zone calculated in step 2 and the specific enthalpy value of the tube side inlet and the tube side flow G t calculated in step 1, the outlet temperature of the tube side of the drain zone, that is, the inlet temperature T ti,con of the condensation zone tube side is calculated.

[0093] Step 3.2: Calculate the total heat transfer Q con of the condensation zone heat transfer tube. According to the total heat transfer Q t of the heat transfer tube calculated in step 1, subtract the heat transfer Q d of the drain zone calculated in step 2 to get.

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

[0095] Using the heat transfer efficiency method, according to the condensation zone heat transfer Q con , the saturation temperature T sat , the heat transfer area, the condensation zone tube side inlet temperature T ti,con , the tube side flow G t , calculate Eff con and h con .

[0096] Step 4: Calculate the state of the steam extraction pipeline and the upper drain pipeline. The steam extraction pipeline and the upper drain pipeline include: the steam extraction pipeline (flowing in), the drain pipeline of the upper drain tank (flowing in), and the drain pipeline of the upper feed water heater (flowing in).

[0097] (1) The steam extraction pipeline usually has a pressure and temperature sensor, and the temperature sensor has higher reliability and accuracy. The pressure value is obtained by querying the saturated steam property table with the temperature measurement result, and the steam extraction flow value is calculated according to the steam extraction pressure calculation result and the feed water heater saturation pressure using the steam extraction pipeline resistance model.

[0098] (2) Normally, a valve position sensor is provided in the drain line of the upper drain tank, and the upper drain tank is provided with pressure, temperature and water level sensors. First, the drain outlet pressure is calculated according to the pressure and water level measurement results. Then, the drain specific enthalpy is calculated by using the drain outlet pressure calculation result and the temperature measurement result to query the water and steam property table. Finally, the drain flow rate is calculated according to the valve position and pressure value by using the pipe resistance model.

[0099] (3) Normally, a valve position sensor and a drain temperature sensor are provided in the drain line of the upper feedwater heater. First, the drain pressure estimation value and the specific enthalpy estimation value are obtained by querying the saturated water property table according to the drain temperature measurement result. Then, the drain flow rate value is calculated according to the pressure and valve position by using the pipe resistance model.

[0100] Embodiment

[0101] As shown in the following, the specific implementation process of the present application is described by taking a certain pressurized water reactor No. 6 high-pressure feedwater heater as an example. The relevant measurement point arrangement of the feedwater heater is shown in the following table 1: Figures 2 to 4 Figure 2

[0102] Table 1: Measurement point summary of No. 6 high-pressure feedwater heater

[0103]

[0104]

[0105] Step 1: Calculate the tube side state according to the tube side measurement point data of the feedwater heater. Specifically as follows:

[0106] Step 1.1: Calculate the flow rate value G according to the tube side inlet and outlet pressure measurement results by using the following pipe resistance model t . The formula is as follows:

[0107]

[0108] Wherein, a t is the pipe flow conductance coefficient value, which is calculated by the pipe structure and friction coefficient mechanism; p t,i is the tube side inlet pressure; p t,o is the tube side outlet pressure.

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

[0110]

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

[0112] ​​Step 1.3: Based on the principle of energy conservation, the enthalpy rise value of the tube side fluid, i.e. the total heat transfer amount Q of the heat transfer tube, is calculated using the following formula st . The formula is as follows:

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

[0114] Wherein, H(T t,o ) is the specific enthalpy value calculated according to the outlet temperature of the tube side; H(T t,i ) is the specific enthalpy value calculated according to the inlet temperature of the tube side.

[0115] Step 2: Calculate the state of the feedwater heater shell side and the drain outlet pipeline. Specifically as follows:

[0116] Step 2.1: Set the upper and lower limit values of the feedwater heater saturation temperature T max = the measured value of the drain outlet temperature + 100 and T min = the measured value of the drain outlet temperature + 0.01, and set the saturation temperature convergence error η = 1.0e-8.

[0117] Calculate the estimated value of the feedwater heater saturation temperature TT sat , and then start the iterative calculation.

[0118]

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

[0120] According to the saturation temperature T sat , query the saturated water and steam property table to obtain the saturation pressure, i.e. the shell side pressure Ps:

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

[0122] Wherein, f Psat represents the relationship between temperature and pressure in the saturated water property table;

[0123] The shell side pressure plus the water level pressure head obtains 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 steam outlet flow value G according to the valve position measurement result, the pressure measurement result of the downstream deaerator and condenser and the steam outlet pressure P do The steam outlet flow value G is calculated do .

[0126] The pipeline resistance model with a valve is shown in the following formula:

[0127]

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

[0129] Step 2.3: Calculate the total heat transfer coefficient h of the steam outlet area of the feedwater heater d The total heat transfer coefficient of the steam outlet area is composed of the tube side convective heat transfer coefficient h t , the tube wall heat transfer coefficient h w and the shell side convective heat transfer coefficient h sd :

[0130]

[0131] Wherein, the tube wall heat transfer coefficient h w can be calculated according to the tube wall thickness and the thermal conductivity coefficient. λ is the thermal conductivity coefficient of the tube wall, and k is the tube wall thickness. h sd is calculated according to the Zhuka relationship.

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

[0133] According to the water level measurement result and the arrangement height of the heat transfer tube of the feedwater heater, the heat transfer area A d of the steam outlet area and the heat transfer area A con of the condensation area are calculated.

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

[0135] The heat transfer quantity is calculated by the heat transfer efficiency method according to the tube side inlet temperature and flow, the shell side saturation temperature and steam flow, the total heat transfer coefficient of the steam outlet area, and the heat transfer area of the steam outlet area. The heat transfer quantity calculation formula is shown in the following formula, wherein 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 saturation temperature Tsat of the feedwater heater.

[0138] Firstly, according to the measured temperature of the steam outlet T do and the steam pressure P do of Step 2.2, the specific enthalpy H do of the steam outlet is obtained by consulting the steam property table.

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

[0140] Then, the energy conservation principle is used to calculate the specific enthalpy H sat at the liquid level of the feedwater heater, combined with the heat transfer Q d of Step 2.5 and the steam flow G do of Step 2.2, as shown in the following formula:

[0141]

[0142] Finally, according to H sat , the saturation temperature T sat is obtained by consulting the saturated water property table, and compared with the estimated saturation temperature TT sat of Step 2.1.

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

[0144] dT = TT sat -TT sat

[0145] (1) If the error dT is less than the value of η, it is considered that the saturation temperature of the feedwater heater is calculated correctly, and the iteration calculation is exited to enter Step 3.

[0146] (2) Otherwise, the maximum saturation temperature T max and the minimum saturation temperature T min in Step 2.1 are used as the estimated temperature TT sat to calculate the respective estimated errors dT Tmax and dT Tmin . Finally, the upper and lower limits of the saturation temperature of the feedwater heater T max and T min are updated, and the iteration calculation is restarted from Step 2.1. If dT and dT Tmax are of the same sign during the updating process, TT sat is used to replace T max, similarly if dT and dT Tmin If the number is the same, use TT 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 rate Q of the hydrophobic area calculated according to step S2 using the principle of energy conservation is d and pipe side flow G t , calculate the outlet temperature of the hydrophobic 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 tubes in the condensation zone con .

[0152] The total heat transfer heat 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 amount 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 state of the drain line of the upper drain tank. First, calculate the drain outlet pressure according to the pressure and water level measurement results. Then, use the drain outlet pressure calculation result and the temperature measurement result to query the water and steam property table to calculate the drain specific enthalpy. Finally, use the pipe resistance model to calculate the drain flow according to the valve position, the drain tank drain outlet pressure value and the feedwater heater saturation pressure.

[0160] (3) Calculate the state of the drain line of the No. 7 high-pressure feedwater heater. Similarly, first, use the drain temperature measurement result to query the saturated water property table to obtain the drain pressure estimation value and the specific enthalpy estimation value, and then use the pipe resistance model to calculate the drain flow value according to the pressure and the valve position.

[0161] In order to verify the calculation effect of the method, simulation data is generated by using a nuclear power plant full-range simulator, and the simulation data is used as the No. 6 high-pressure feedwater heater measurement point and the operation performance sample library. The measurement point data in the sample library is processed by using the method, and the calculation result is compared with the operation performance reference value. The relative error change curve is shown in FIG. 2 and FIG. 3. Figure 3 and Figure 4 As shown in the curves, the relative error is far less than 1%, which indicates that the method has good calculation accuracy.

[0162] The above merely describes the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily thought by those skilled in the art, and should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to 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 feedwater heater shell side and drain outlet pipeline; Step 3: Calculate the heat transfer performance of the condensation zone, including the heat transfer efficiency and condensation heat transfer coefficient of the condensation zone. Step 3 specifically includes: Step 3.1: The heat transfer Q of the hydrophobic area calculated in step 2 d and pipe side flow G t , calculate the outlet temperature of the hydrophobic zone tube side, and obtain the inlet temperature T of the condensation zone tube side ti,con : Where, T t,i is the tube side inlet temperature, cp liq is the specific heat value of liquid phase at constant pressure; 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: Where Q con is the heat transfer in the condensation zone, T sat 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 t is the tube side convective heat transfer coefficient, h s is the total heat transfer coefficient between shell-side steam and tube-side feed water; 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 rate value G based on the pipe side inlet and outlet pressure measurement results t : Where a t is the pipeline conductivity coefficient, p t,i is the measured value of the pipe side inlet pressure, p t,o is the measured value of the pipe side outlet pressure; Step 1.2: Calculate the tube-side heat transfer coefficient h using the forced convection heat transfer mechanism inside 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 measured pressure and temperature on the tube side, and 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 )]; Where, 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 Calculated 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 area; Step 2.4: Calculate the heat transfer area of ​​the feedwater heater heat transfer tube; Step 2.5: Calculate the heat transfer of the drain area of ​​the feedwater heater; Step 2.6: Calibrate 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 saturation 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 physical 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 phase density value is obtained by querying the saturated water physical 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 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 : Where a do is the pipeline conductance value, which is calculated based on 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 measurement values ​​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 estimated value TT sat The heat transfer efficiency eff of the hydrophobic zone is calculated to obtain the heat transfer Q of the hydrophobic 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 liquid phase constant pressure specific heat value, T t,i is the tube side 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, 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 liquid level of the feedwater heater 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 physical properties table of saturated water; If the error dT between the two is less than the value of η, the saturation temperature of the feedwater heater is considered to be calculated correctly, and the iterative calculation is exited and the process is entered into step 3; 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 Calculate the temperature error dTT max and dTT min ; According to dT, dTT max and dTT min Update iteration range, i.e. T max and T min ,use Update estimated temperature TT sat After iterating again, the update iteration range method is as follows: If dT and dTT max If the signs of T are consistent max Get TT sat Value, similarly if dT and dTT min If the signs of T are consistent 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: 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 rate is calculated based on the valve position and pressure value using the pipeline resistance model.

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

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