A method and device for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant

Abstract

The present invention provides a method and device for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant, including: S1: obtaining the equipment structure parameters of the deaerator of a given unit and the real-time operation data of the unit; S2: calculating the extraction steam specific enthalpy entering the deaerator according to the obtained real-time operation data; S3: solving the steam space steady-state enthalpy balance model in the deaerator model to obtain the simulation value of the steam condensation rate in the steam space; S4: solving the water space model in the deaerator model to obtain the simulation value of the deaerator water level; S5: solving the steam space model in the deaerator model to calculate the extraction steam mass flow rate and the steam condensation rate in the steam space; S6: iterating S4-S5 until the difference between the extraction steam mass flow rates calculated in two adjacent times is less than a given threshold to obtain the simulation value of the deaerator water level and the real-time calculated value of the extraction steam mass flow rate. The present invention can realize the real-time estimation of the extraction steam mass flow rate of the deaerator in a nuclear power plant and solve the problem that the extraction steam mass flow rate cannot be measured in real time.

Description

Technical Field

[0001] The present invention belongs to the technical field of operation optimization control of nuclear power plants. Specifically, it relates to a method and device for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant. Background Art

[0002] The deaerator is an important auxiliary equipment in the power plant. It uses the extraction steam of the steam turbine to heat the feed water to the saturation temperature, removes gases such as oxygen in the feed water, and prevents equipment corrosion. At the same time, as a mixing heat exchanger, the deaerator heats the feed water, increases the specific enthalpy of the feed water, and improves the thermal cycle efficiency of the power plant. In addition, the deaerator water tank also provides a certain storage capacity, which can provide a buffer for the phase mismatch between the steam generator and the condenser.

[0003] According to the spatial position and aggregation state of the working medium, the working medium can be divided into two parts: the steam space and the water space. After the feed water at the inlet of the deaerator is mixed with the drain water of the high-pressure feed water heater and the drain water of the steam-water separation reheater, it forms a divergent conical water film through the high-pressure nozzle and sprays downward. The water film fully contacts the upward steam in this area, quickly heats the water to the saturation temperature under the pressure of the deaerator, and causes most of the oxygen to precipitate from the water and be discharged to the surrounding environment through the exhaust ports around the nozzle. The preliminarily deaerated water droplets flow into the water space, and the extraction steam of the steam turbine is sent from underwater through the drain pipe and mixed and heat-exchanged with the water in the water space to achieve deep deaeration.

[0004] The extraction steam flow rate of the steam turbine is of great significance for monitoring the operation state of the deaerator, but there is no real-time flow measurement point. The existing technology generally calculates the extraction steam flow rate by establishing an enthalpy balance equation for the working medium at the inlet and outlet of the deaerator. However, the enthalpy balance equation only considers the temperature and flow rate of the working medium at the inlet and outlet, and ignores the dynamic characteristics inside the deaerator, resulting in low time accuracy and poor anti-interference ability of the calculation results.

[0005] After retrieving the existing technology, it is found that the Chinese invention patent "Data Calibration Method and System for the Digital Twin Model of a Deaerator Based on Adaptive Cubature Kalman Filter" with the application number CN202110027193.X and the application date of January 9, 2021, established a digital twin model of the deaerator and an adaptive cubature Kalman filter observer, which can be used for real-time calculation of the extraction steam flow rate of the deaerator. The key extraction steam flow rate of the deaerator is solved by using the Bernoulli differential pressure-flow formula. However, due to the long extraction steam pipeline, the frictional pressure drop and local pressure drop are large and cannot be quantitatively calculated, so the calculation result of the Bernoulli formula is not accurate.

[0006] In summary, none of the existing publicly reported technologies involve a real-time determination method for the extraction steam flow rate based on the mechanism model of the deaerator in a nuclear power plant, and this gap needs to be filled. Summary of the Invention

[0007] In view of the deficiencies of the prior art, the present invention provides a method and device for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant.

[0008] In a first aspect of the present invention, there is provided a method for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant, specifically including:

[0009] S1: Obtain the equipment structure parameters of the deaerator of a specified nuclear power unit and the real-time operation data of the unit;

[0010] S2: Calculate the extraction steam specific enthalpy entering the deaerator based on the real-time operation data of the nuclear power plant obtained in S1;

[0011] S3: Based on the extraction steam specific enthalpy obtained in S2, solve the steam space steady-state enthalpy balance model in the deaerator mechanism model to obtain the simulation value of the steam condensation rate in the steam space;

[0012] S4: According to the simulation value of the steam condensation rate in the steam space obtained in S3 or S5, solve the water space model in the deaerator mechanism model to obtain the deaerator water level simulation value;

[0013] S5: According to the deaerator water level simulation value obtained in S4, solve the steam space model in the deaerator model to calculate the extraction steam mass flow rate and the simulation value of the steam condensation rate in the steam space;

[0014] S6: Substitute the simulation value of the steam condensation rate in the steam space calculated in S5 back into S4, and iteratively calculate S4 - S5 until the difference between the extraction steam mass flow rates obtained from two adjacent calculations is less than a given threshold, to obtain the real-time calculation value of the extraction steam mass flow rate.

[0015] In a second aspect of the present invention, there is provided a readable medium, on which instructions are stored, and when the instructions are executed on an electronic device, the electronic device is caused to execute the above-mentioned deaerator model and extraction steam mass flow rate determination method.

[0016] In a third aspect of the present invention, there is provided an electronic device, including a memory, a processor, and a computer program stored on the memory and capable of running on the processor, and when the processor executes the program, it is used to execute the above-mentioned method for real-time determination of the extraction steam flow rate of a nuclear power saturated steam steam turbine.

[0017] Compared with the prior art, the embodiments of the present invention have at least one of the following beneficial effects:

[0018] The present invention provides a method for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant. According to the real-time data of the DCS in the nuclear power plant, the extraction steam specific enthalpy and mass flow rate entering the deaerator can be calculated, solving the problem that the extraction steam flow rate cannot be measured in real time. Compared with the prior art, the method provided by the present invention has the advantages of accurate calculation results, strong anti-interference ability, high real-time performance, etc. The method provided by the present invention is of great significance for the evaluation of the thermal economy of the secondary loop of the nuclear power plant and the development of the digital twin system.

[0019] In the above method of the present invention, the measuring point data required for the real-time calculation of the deaerator model and the inlet extraction steam mass flow rate are all provided by the DCS real-time database. There is no need to additionally add measuring points or other expensive hardware on site. Only a corresponding software module needs to be added to the existing control system, and the cost is low. Description of the Drawings

[0020] By reading the detailed description of the non-limiting embodiments with reference to the following drawings, other features, objects, and advantages of the present invention will become more apparent.

[0021] Figure 1 is the structural diagram of the deaerator in an embodiment of the present invention;

[0022] Figure 2 is the flowchart of the method for real-time determination of the extraction steam mass flow rate of the deaerator in a nuclear power plant in an embodiment of the present invention;

[0023] Figure 3 is the output power change diagram of the nuclear power unit in an embodiment of the present invention;

[0024] Figure 4 is the comparison between the calculated value of the extraction steam flow rate at the inlet of the deaerator and the calculation results of the existing method in an embodiment of the present invention;

[0025] Figure 5 is the calculation result and verification of the deaerator water level in an embodiment of the present invention. Detailed Embodiments

[0026] The present invention will be described in detail below with reference to specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that those of ordinary skill in the art can make several deformations and improvements without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0027] Figure 1 is the structural diagram of the deaerator in an embodiment of the present invention. This embodiment is applied to a 1000MW-class nuclear power unit. The deaerator used in this embodiment is a horizontal headless spray deaerator. According to the spatial position and aggregation state of the working medium, the deaerator can be divided into a steam space and a water space.

[0028] In the embodiment of the present invention, a method for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant constructs a mechanism model of the deaerator in the nuclear power plant. Solving this model can obtain the real-time value of the extraction steam mass flow rate entering the deaerator. Specifically, the method is based on the deaerator mechanism model, and the deaerator mechanism model includes a steam space steady-state enthalpy balance model, a water space model, and a steam space model. Among them: the steam space steady-state enthalpy balance model is used to provide an initial value for subsequent calculations, the water space model calculates the water level according to the extraction steam mass flow rate, and the steam space model calculates the extraction steam mass flow rate according to the water level. The extraction steam mass flow rate of the deaerator is obtained through iterative calculation of the water space model and the steam space model.

[0029] Figure 2 is a flowchart of the method for real-time determination of the extraction steam mass flow rate of a deaerator in a nuclear power plant in an embodiment of the present invention. Referring to Figure 2 as shown, the method in this embodiment includes the following steps:

[0030] S1: Obtain the equipment structure parameters of the deaerator of the nuclear power unit and the real-time operation data of the unit.

[0031] S2: Calculate the specific enthalpy of the extraction steam entering the deaerator according to the real-time operation data of the nuclear power plant obtained in S1.

[0032] S3: Solve the steam space steady-state enthalpy balance model in the deaerator mechanism model according to the specific enthalpy of the extraction steam of the deaerator obtained in S2 to obtain the condensation rate of the steam in the steam space.

[0033] S4: Solve the water space model in the deaerator mechanism model according to the steam space steam condensation rate obtained in S3 or S5 to obtain the simulated value of the deaerator water level.

[0034] S5: Solve the steam space model in the deaerator model according to the simulated value of the deaerator water level obtained in S4, and calculate the extraction steam mass flow rate and the simulated value of the steam space steam condensation rate.

[0035] S6: Substitute the simulated value of the steam space steam condensation rate calculated in S5 back into S4, and iteratively calculate S4 - S5 until the difference between the extraction steam mass flow rates obtained in two adjacent times is less than a given threshold, and obtain the real-time calculated value of the extraction steam mass flow rate.

[0036] This embodiment can realize the real-time value of the extraction steam mass flow rate of the deaerator in the nuclear power plant, and solves the problem that the extraction steam mass flow rate cannot be measured in real time.

[0037] As a preferred embodiment, in S1, the deaerator can be divided into a steam space and a water space according to the aggregation state of the working medium. Specifically, querying the deaerator manual to obtain the equipment structure parameters of the deaerator includes: the length L of the deaerator water tank d , the radius R of the water tank d ; the real-time operation data of the unit obtained through the DCS includes: the pressure p of the working medium in the deaeratord 、The feed water mass flow rate D at the inlet of the deaerator fw,in and specific enthalpy h fw,in 、The feed water mass flow rate D at the outlet of the deaerator fw,out 、The mass flow rate D of the drain water of the steam-water separator reheater dw,msr and specific enthalpy h dw,msr 、The mass flow rate D of the drain water at the outlet of the high-pressure feed water heater dw,hr and specific enthalpy h dw,hr 、The main steam pressure p ms and specific enthalpy h ms 。

[0038] As a preferred embodiment, in S2, calculate the specific enthalpy h es of the extraction steam entering the deaerator, and calculate it using the following formula:

[0039]

[0040]

[0041] Where:

[0042]

[0043]

[0044] In the formula, h es is the specific enthalpy of the extraction steam at the inlet of the deaerator, kJ / kg; h ms is the specific enthalpy of the main steam, kJ / kg; x es and x ms are the humidities of the extraction steam and the main steam at the inlet of the deaerator respectively, dimensionless; η dry and α are the dry-base internal efficiency and the Baumann coefficient of the steam turbine respectively, which are constants obtained according to the steam turbine regulations, dimensionless; Δh s is the isentropic enthalpy drop of the steam turbine stage group, kJ / kg; p d is the working fluid pressure in the deaerator, MPa; h L (p d ) and h V (p d ) are the specific enthalpies of the saturated water and saturated dry steam corresponding to the deaerator pressure respectively, kJ / kg; κ is the logarithmic mean adiabatic index of the stage group, dimensionless; ρ es and ρ ms are the densities of the extraction steam and the main steam at the inlet of the deaerator respectively, kg / m 3 。

[0045] In the above preferred embodiment of the present invention, the above formula is used to solve the problem that the specific enthalpy of the extraction steam of the saturated steam turbine cannot be measured online.

[0046] As a preferred embodiment, in S3, the working medium at the inlet of the deaerator steam space includes: inlet feed water, desuperheater drain water from the steam separator, drain water from the high-pressure feedwater heater, and steam extraction from the steam turbine. The mass flow rate of the steam extraction is D e There are no measured data. The steady-state enthalpy balance model in the deaerator's steam space is the mass and energy balance relationship of the working medium at the inlet and outlet of the deaerator's steam space. Based on this steady-state enthalpy balance model of the steam space, the mass flow rate of the steam extraction can be roughly calculated to provide an initial value for the calculations in S4 - S5:

[0047] D c = D es

[0048] D fw,in + D dw,msr + D dw,hr + D es - D s = 0

[0049] D fw,in h fw,in + D dw,msr h dw,msr + D dw,hr h dw,hr + D es h es - D s h L (p d ) = 0

[0050] In the formula, D c is the steam condensation rate in the deaerator steam space, kg / s; D fw,in is the mass flow rate of the inlet feed water to the deaerator, kg / s; h fw,in is the specific enthalpy of the inlet feed water to the deaerator, kJ / kg; D dw,msr is the mass flow rate of the drain water from the outlet of the desuperheater of the steam separator, kg / s; h dw,msr is the specific enthalpy of the drain water from the outlet of the desuperheater of the steam separator, kJ / kg; D dw,hr is the mass flow rate of the drain water from the outlet of the high-pressure feedwater heater, kg / s; h dw,hr is the specific enthalpy of the drain water from the outlet of the high-pressure feedwater heater, kJ / kg; D es is the mass flow rate of the steam extraction at the inlet of the deaerator, kg / s; h es is the specific enthalpy of the steam extraction at the inlet of the deaerator, kJ / kg; D s is the mass flow rate of the saturated water entering the water space from the deaerator steam space, kg / s; h L (p d ) is the specific enthalpy of the saturated water corresponding to the deaerator pressure, kJ / kg.

[0051] As a preferred embodiment, in S4, the simulated value of the deaerator water level is obtained by solving the deaerator water space model. Specifically, the water space model describes the changes in the mass and energy of the water in the deaerator caused by steam condensation, including:

[0052] (a) Calculate the total mass M of the working medium in the deaerator water space according to the condensation rate D of the steam in the deaerator steam space c and the feed water mass flow rate D at the deaerator outlet fw,out : w :

[0053]

[0054] In the formula, M w is the total mass of the working medium in the deaerator water space, kg; D fw,out is the feed water mass flow rate at the deaerator outlet, kg / s;

[0055] (b) Calculate the total energy E of the working medium in the deaerator water space w and the average specific enthalpy h w :

[0056]

[0057]

[0058] In the formula, E w is the total energy of the working medium in the deaerator water space, kJ; p d is the pressure of the working medium in the deaerator, Mpa; h L (p d ) is the specific enthalpy of saturated water corresponding to the deaerator pressure, kJ / kg; h w is the average specific enthalpy of the working medium in the water space, kJ / kg;

[0059] (c) According to the total mass M of the working medium in the deaerator water space obtained in (a) w and the average specific enthalpy h of the working medium in the water space obtained in (b) w , calculate the volume V of the deaerator water space w and the simulated value L of the deaerator water level w :

[0060]

[0061]

[0062] In the formula, V w is the volume of the deaerator water space, m 3 ; ρ w (p d ,h w ) is the working medium pressure p d, specific enthalpy h w corresponding density, kg / m 3 ; L d is the length of the deaerator tank, m; R d is the radius of the deaerator tank, m; L w is the simulated value of the deaerator water level, m.

[0063] As a preferred embodiment, in S5, the steam condensation rate D c in the steam space and the extraction steam mass flow rate D es are obtained by solving the deaerator steam space model. The steam space model describes the change in the extraction steam mass flow rate caused by the volume and energy changes in the steam space, takes into account the dynamic process inside the deaerator, and solves the problem that the steam condensation rate in the steam space cannot be measured. Specifically, the steam space model includes:

[0064] (a) According to the simulated value L w of the deaerator tank water level calculated in S4, calculate the volume V v of the deaerator steam space:

[0065]

[0066] In the formula, V v is the volume of the deaerator steam space, m 3 ; L w is the simulated value of the deaerator tank water level, m; L d is the length of the deaerator tank, m; R d is the radius of the deaerator tank, m;

[0067] (b) According to the volume of the deaerator steam space calculated in (a), calculate the total mass M v and the total energy E v of the deaerator steam space:

[0068] M v = V v ρ V (p d )

[0069] E v = M v h V (p d )

[0070] In the formula, M v is the total mass of the working fluid in the deaerator steam space, kg; E v is the total energy of the working fluid in the deaerator steam space, kJ; p d is the pressure of the working fluid in the deaerator, MPa; ρ V (p d ) is the saturated steam density corresponding to the deaerator pressure, kg / m3 ; h V (p d ) is the specific enthalpy of saturated steam corresponding to the deaerator pressure, kJ / kg;

[0071] (c) Calculate the extraction steam mass flow rate D es and the steam condensation rate D in the steam space c :

[0072]

[0073]

[0074] D c = D s - D fw,in - D dw,msr - D dw,hr

[0075] In the formula, D fw,in is the feed water mass flow rate at the deaerator inlet, kg / s; h fw,in is the specific enthalpy of the feed water at the deaerator inlet, kJ / kg; D dw,msr is the mass flow rate of the drain water at the outlet of the steam-water separation and reheater, kg / s; h dw,msr is the specific enthalpy of the drain water at the outlet of the steam-water separation and reheater, kJ / kg; D dw,hr is the mass flow rate of the drain water at the outlet of the high-pressure feed water heater, kg / s; h dw,hr is the specific enthalpy of the drain water at the outlet of the high-pressure feed water heater, kJ / kg; D es is the extraction steam mass flow rate at the deaerator inlet, kg / s; D c is the steam condensation rate in the deaerator steam space, kg / s; h es is the specific enthalpy of the extraction steam at the deaerator inlet, kJ / kg; D s is the mass flow rate of the saturated water entering the water space from the deaerator steam space, kg / s; h L (p d ) is the specific enthalpy of saturated water corresponding to the deaerator pressure, kJ / kg.

[0076] As a preferred embodiment, in S6, iterate S4 - S5 several times, and terminate the calculation when the difference between the results of two adjacent times is less than the threshold. The termination condition is:

[0077] ||D es (i) - D es (i - 1)||2 < ε es

[0078] In the formula, D es (i) represents the extraction steam mass flow rate obtained from the i-th iterative calculation, kg / s; ε es is a pre-set threshold, kg / s.

[0079] In an embodiment of the method for real-time determination of the extraction steam mass flow rate of the deaerator in a nuclear power plant according to the present invention, it is first necessary to obtain the actual measured data of the DCS of the nuclear power unit. Among them, the output power of the unit is shown in Figure 3 .

[0080] Figure 4 Figure 8 is a comparison between the extraction steam mass flow rate value at the deaerator inlet and the results of the existing method in an embodiment of the present invention: Compared with the widely used enthalpy balance calculation method, the calculation result of the method in the embodiment of the present invention is stable and has strong anti-interference ability; compared with the Bernoulli equation, the method in the embodiment of the present invention calculates correctly and will not cause the accumulation of errors.

[0081] Figure 5 Figure 12 is a comparison between the simulation result and the measured value of the deaerator water level in an embodiment of the present invention, and the average error of the water level calculation is about 5.2 mm. The water level of the deaerator is an important coupling variable between the steam space model and the water space model of the deaerator constructed in the embodiment of the present invention. According to the consistency between the simulated value and the measured value of the water level, the correctness of the deaerator model and the extraction steam mass flow rate determination method in the embodiment of the present invention can be indirectly verified.

[0082] In another embodiment of the present invention, a readable medium is further provided, on which instructions are stored, and when the instructions are executed on an electronic device, the electronic device is caused to execute the deaerator model and the extraction steam mass flow rate determination method in any one of the above embodiments.

[0083] In another embodiment of the present invention, an electronic device is further provided, including a memory, a processor, and a computer program stored on the memory and capable of running on the processor. When the processor executes the program, it is used to execute the method for real-time determination of the extraction steam flow rate of the nuclear power saturated steam steam turbine in any one of the above embodiments.

[0084] Next, taking Figure 1 the structure of the deaerator as an example, the implementation of the technical solution of the present invention will be described in combination with the detailed equipment structure and its operation conditions:

[0085] S1, query the deaerator manual to obtain the equipment structure parameters of the deaerator: the length L of the deaerator water tank d is 50 m, and the radius R of the water tank d is 2.57 m;

[0086] At a certain moment, obtain the real-time operation data of the unit through the DCS: the working medium pressure p in the deaerator d is 0.8944 MPa, the feed water mass flow rate D at the deaerator inlet fw,in is 1012 kg / s and the specific enthalpy h fw,in is 579.3 kJ / kg, the feed water mass flow rate D at the deaerator outlet fw,outis 1561 kg / s, the mass flow rate D of the drain water of the steam-water separator reheater dw,msr is 169.6 kg / s and the specific enthalpy h dw,msr is 756.3 kJ / kg, the mass flow rate D of the drain water at the outlet of the high-pressure feedwater heater dw,hr is 255.6 kJ / kg and the specific enthalpy h dw,hr is 751.9 kJ / kg, the main steam pressure p ms is 6.762 MPa and the specific enthalpy h ms is 2769 kJ / kg.

[0087] S2, calculate the specific enthalpy h of the extraction steam entering the deaerator es , and calculate it using the following formula:

[0088]

[0089]

[0090] Where:

[0091]

[0092]

[0093] In the formula, h ms is the specific enthalpy of the main steam, 2769 kJ / kg; x es and x ms are the moisture contents of the extraction steam at the inlet of the deaerator and the main steam respectively, which are 0.8586 and 0.9953; η dry and α are the dry-base internal efficiency and the Baumann coefficient of the steam turbine, which are 0.8744 and 1.3 respectively according to the steam turbine regulations; Δh s is the isentropic enthalpy drop of the steam turbine stage group, and the calculated result is 358.6 kJ / kg; h L (p d ) and h V (p d ) are the specific enthalpies of the saturated water and saturated dry steam corresponding to the deaerator pressure, which are 744.3 kJ / kg and 2773 kJ / kg respectively; κ is the logarithmic mean adiabatic index of the stage group, and the calculated result is 1.0759; ρ es and ρ ms are the densities of the extraction steam at the inlet of the deaerator and the main steam respectively, which are 35.30 kg / m 3 and 5.460 kg / m 3 .

[0094] According to the above steps, the specific enthalpy h of the extraction steam entering the deaerator es is 2487 kJ / kg.

[0095] S3, Solve the steam space steady-state enthalpy balance model in the deaerator mechanism model:

[0096] D c = D es

[0097] D fw,in + D dw,msr + D dw,hr + D es - D s = 0

[0098] D fw,in h fw,in + D dw,msr h dw,msr + D dw,hr h dw,hr + D es h es - D s h L (p d ) = 0

[0099] In the formula, D fw,in is the feed water mass flow rate at the deaerator inlet, which is 1012 kg / s; h fw,in is the specific enthalpy of the feed water at the deaerator inlet, which is 579.3 kJ / kg; D dw,msr is the mass flow rate of the drain water at the outlet of the steam-water separation reheater, 169.6 kg / s; h dw,msr is the specific enthalpy of the drain water at the outlet of the steam-water separation reheater, 756.3 kJ / kg; D dw,hr is the mass flow rate of the drain water at the outlet of the high-pressure feed water heater, 255.6 kg / s; h dw,hr is the specific enthalpy of the drain water at the outlet of the high-pressure feed water heater, 751.9 kJ / kg; h es is the specific enthalpy of the extraction steam entering the deaerator obtained in S2, 2487 kJ / kg; h L (p d ) is the specific enthalpy of the saturated water corresponding to the deaerator pressure, 741.6 kJ / kg.

[0100] Obtain the steam condensation rate D c in the deaerator steam space to be 91.17 kg / s;

[0101] S4, Solve the deaerator water space model in the deaerator mechanism model:

[0102] (a) According to the steam condensation rate D c in the deaerator steam space and the feed water mass flow rate D fw,out at the deaerator outlet, calculate the total mass M w of the working medium in the deaerator water space:

[0103]

[0104] In the formula, D fw,out is the feed water mass flow rate at the outlet of the deaerator, which is 1561 kg / s;

[0105] The total mass M of the working medium in the water space of the deaerator is obtained w as 55310 kg;

[0106] (b) Calculate the total energy E of the working medium in the water space of the deaerator w and the average specific enthalpy h w :

[0107]

[0108]

[0109] The total energy E of the working medium in the water space of the deaerator is obtained w as 4.099×10 8 kJ; the average specific enthalpy h of the working medium in the water space is w 741.3 kJ / kg;

[0110] (c) According to the total mass M of the working medium in the water space of the deaerator obtained in (a) w and the average specific enthalpy h of the working medium in the water space obtained in (b) w , calculate the volume V of the water space of the deaerator w and the simulated value L of the deaerator water level w :

[0111]

[0112]

[0113] In the formula, V w is the volume of the water space of the deaerator, m 3 ; ρ w (p d , h w ) is the density corresponding to the working medium pressure p d , specific enthalpy h w , which is 892.2429 kg / m 3 ; L d is the length of the deaerator water tank, which is 50 m; R d is the radius of the deaerator water tank, which is 2.57 m;.

[0114] The volume V of the water space of the deaerator is obtained w as 619.8577 m 3 ; L w is the simulated value of the deaerator water level, which is 2.978 m.

[0115] S5, Solve the steam space model in the deaerator mechanism model:

[0116] (a) Calculate the simulated value L of the deaerator water tank level obtained according to S4 w , and calculate the volume V of the deaerator steam space v :

[0117]

[0118] Obtain the volume V of the deaerator steam space v is 417.6 m 3 ;

[0119] (b) Calculate the total mass M and total energy E of the deaerator steam space according to the volume of the deaerator steam space obtained in (a): v and total energy E v :

[0120] M v = V v ρ V (p d )

[0121] E v = M v h V (p d )

[0122] In the formula, ρ V (p d ) is the saturated steam density corresponding to the deaerator pressure, which is 4.621 kg / m 3 ; h V (p d ) is the saturated steam specific enthalpy corresponding to the deaerator pressure, which is 2773 kJ / kg;

[0123] Obtain the total mass M of the working medium in the deaerator steam space v is 1913 kg; the total energy E of the working medium in the deaerator steam space v is 5.305×10 6 kJ;

[0124] (c) Calculate the extraction steam mass flow rate D es and the steam condensation rate D c in the steam space:

[0125]

[0126]

[0127] D c = D s - D fw,in - D dw,msr - D dw,hr

[0128] Obtain D es is the extraction steam mass flow rate at the inlet of the deaerator, 91.08 kg / s;

[0129] S6. Iterate S4 - S5 for several times. When the difference between the results of two adjacent times is less than the threshold, terminate the calculation. The termination condition is:

[0130] ||D es (i) - D es (i - 1)||2 < ε es

[0131] where ε es is a pre - set threshold value, with a value of 0.01 kg / s.

[0132] Obtain the extraction steam mass flow rate D of the deaerator es is 91.01 kg / s.

[0133] The above embodiments of the present invention can realize the real - time estimation of the extraction steam mass flow rate of the deaerator in a nuclear power plant, solve the problem that the extraction steam mass flow rate cannot be measured in real time, and can also be used for the thermal economic evaluation of the secondary loop of a nuclear power plant and the digital twin system. The results of the above embodiments of the present invention have the advantages of stable and accurate calculation results, strong anti - interference ability, and high real - time performance compared with the existing methods. The results obtained in the embodiments of the present invention can be directly used for the real - time online monitoring of the deaerator in a nuclear power plant. Specifically, after obtaining the real - time value of the above - mentioned extraction steam mass flow rate of the deaerator, it can be compared with the set monitoring threshold. If it exceeds the set monitoring threshold, an alarm will be issued to achieve real - time online monitoring, which plays an important auxiliary role in the operation monitoring of the deaerator in a nuclear power plant.

[0134] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above - mentioned specific embodiments, and those skilled in the art can make various deformations or modifications within the scope of the claims, which does not affect the essence of the present invention.

Claims

1. A real-time determination method for the extraction steam mass flow rate of a deaerator in a nuclear power plant, characterized in that, The method is based on a deaerator mechanism model, which includes a steam space steady-state enthalpy balance model, a water space model, and a steam space model; The method specifically includes: S1: Obtain the equipment structure parameters of the deaerator of the nuclear power unit and the real-time operation data of the unit; S2: Calculate the extraction steam specific enthalpy entering the deaerator according to the real-time operation data of the nuclear power plant obtained in S1; S3: Based on the extraction steam specific enthalpy obtained in S2, solve the steam space steady-state enthalpy balance model in the deaerator mechanism model to obtain the simulation value of the steam condensation rate in the steam space; S4: According to the simulation value of the steam condensation rate in the steam space obtained in S3 or S5, solve the water space model in the deaerator mechanism model to obtain the simulation value of the deaerator water level; S5: According to the simulation value of the deaerator water level obtained in S4, solve the steam space model in the deaerator model to calculate the extraction steam mass flow rate and the simulation value of the steam condensation rate in the steam space; S6: Substitute the simulation value of the steam condensation rate in the steam space calculated in S5 back into S4, and iteratively calculate S4 - S5 until the difference between the extraction steam mass flow rates obtained in two adjacent times is less than a given threshold, to obtain the real-time calculated value of the extraction steam mass flow rate; In S2, the extraction steam specific enthalpy h entering the deaerator es is calculated using the following formula: Wherein: where h es is the enthalpy of the extraction steam at the deaerator inlet, kJ / kg; h ms is the enthalpy of the main steam, kJ / kg; x es is the moisture content of the extraction steam at the deaerator inlet, x ms is the moisture content of the main steam at the deaerator inlet, dimensionless; η dry and α are respectively the dry-base internal efficiency and the Baumann coefficient of the steam turbine, which are constants obtained according to the steam turbine regulations, dimensionless; Δh s is the isentropic enthalpy drop of the steam turbine stage group, kJ / kg; p d is the pressure of the working fluid in the deaerator, MPa; h L (p d ) is the specific enthalpy of the saturated water corresponding to the deaerator pressure, h V (p d ) is the specific enthalpy of the saturated dry steam corresponding to the deaerator pressure, kJ / kg; κ is the logarithmic mean adiabatic index of the stage group, dimensionless; ρ es is the density of the extraction steam at the deaerator inlet, ρ ms is the density of the main steam at the deaerator inlet, kg / m 3 ; In S3, the steam space steady-state enthalpy balance model in the deaerator mechanism model is the mass and energy balance relationship of the working medium at the inlet and outlet of the deaerator steam space, specifically as follows: D c = D es D fw,in +D dw,msr +D dw,hr +D es -D s = 0 D fw,in h fw,in +D dw,msr h dw,msr +D dw,hr h dw,hr +D es h es -D s h L (p d ) = 0 where D c is the condensation rate of the steam in the deaerator steam space, kg / s; D fw,in is the feed water mass flow rate at the deaerator inlet, kg / s; h fw,in is the specific enthalpy of the feed water at the deaerator inlet, kJ / kg; D dw,msr is the mass flow rate of the drain water at the outlet of the moisture separator reheater, kg / s; h dw,msr is the specific enthalpy of the drain water at the outlet of the moisture separator reheater, kJ / kg; D dw,hr is the mass flow rate of the drain water at the outlet of the high-pressure feed water heater, kg / s; h dw,hr is the specific enthalpy of the drain water at the outlet of the high-pressure feed water heater, kJ / kg; D es is the mass flow rate of the extraction steam at the deaerator inlet, kg / s; h es is the specific enthalpy of the extraction steam at the deaerator inlet, kJ / kg; D s is the mass flow rate of the saturated water entering the water space from the steam space of the deaerator, kg / s; h L (p d ) is the specific enthalpy of the saturated water corresponding to the deaerator pressure, kJ / kg; In S4, solving the water space model in the deaerator mechanism model to obtain the simulation value of the deaerator water level includes: (a) Calculate the total mass M of the working medium in the water space of the deaerator based on the condensation rate D of the steam in the steam space of the deaerator c and the feed water mass flow rate D at the outlet of the deaerator fw,out : w ​ Where, M w is the total mass of the working medium in the water space of the deaerator, kg; D fw,out is the feed water mass flow rate flowing out of the deaerator, kg / s; (b) Calculate the total energy E of the working medium in the deaerator water space w and the average specific enthalpy h of the working medium in the water space w : where, E w is the total energy of the working medium in the water space of the deaerator, kJ; p d is the pressure of the working medium in the deaerator, Mpa; h L (p d ) is the specific enthalpy of saturated water corresponding to the deaerator pressure, kJ / kg; h w is the average specific enthalpy of the working medium in the water space, kJ / kg; (c) The total mass M of the working medium in the deaerator water space obtained from (a) w and the average specific enthalpy h of the working medium in the water space obtained from (b) w , calculate the volume V of the deaerator water space w and the simulated water level value L w : Where, V w is the volume of the deaerator water space, m 3 ; ρ w (p d , h w ) is the density corresponding to the working medium pressure p d and the average specific enthalpy h w of the working medium in the water space, kg / m 3 ; L d is the length of the deaerator water tank, m; R d is the radius of the deaerator water tank, m; L w is the simulated value of the deaerator water level, m; In S5, the steam space model in the deaerator model is solved to obtain the condensation rate D of the steam in the steam space c and the extraction steam mass flow rate D es , including: (a) The simulated value L of the deaerator water tank level obtained according to S4 w , calculate the volume V of the deaerator steam space v : Wherein, V v is the volume of the deaerator steam space, m 3 ; L w is the water level of the deaerator water tank, m; L d is the length of the deaerator water tank, m; R d is the radius of the deaerator water tank, m; (b) Calculate the total mass M and the total energy E of the deaerator steam space based on the volume of the deaerator steam space calculated in (a). v and total energy E v : M v = V v ρ V (p d ) E v = M v h V (p d ) Where M v is the total mass of the working medium in the deaerator steam space, kg; E v is the total energy of the working medium in the deaerator steam space, kJ; p d is the working medium pressure in the deaerator, MPa; ρ V (p d ) is the saturated steam density corresponding to the deaerator pressure, kg / m 3 ; h V (p d ) is the specific enthalpy of saturated dry steam corresponding to the deaerator pressure, kJ / kg; (c) Calculate the extraction steam mass flow rate D es and the steam condensation rate D in the steam space c : D c = D s - D fw,in - D dw,msr - D dw,hr where, D fw,in is the feed water mass flow rate at the inlet of the deaerator, kg / s; h fw,in is the specific enthalpy of the feed water at the inlet of the deaerator, kJ / kg; D dw,msr is the mass flow rate of the drain water at the outlet of the moisture separator reheater, kg / s; h dw,msr is the specific enthalpy of the drain water at the outlet of the moisture separator reheater, kJ / kg; D dw,hr is the mass flow rate of the drain water at the outlet of the high-pressure feed water heater, kg / s; h dw,hr is the specific enthalpy of the drain water at the outlet of the high-pressure feed water heater, kJ / kg; D es is the mass flow rate of the extraction steam at the inlet of the deaerator, kg / s; D c is the steam condensation rate in the steam space of the deaerator, kg / s; h es is the specific enthalpy of the extraction steam at the inlet of the deaerator, kJ / kg; D s is the mass flow rate of the saturated water entering the water space from the steam space of the deaerator, kg / s; h L (p d ) is the specific enthalpy of the saturated water corresponding to the pressure of the deaerator, kJ / kg.

2. The real-time determination method of the extraction steam mass flow rate of the deaerator in a nuclear power plant according to claim 1, characterized in that, In S1, the deaerator is divided into a steam space and a water space according to the aggregation state of the working medium; The equipment structure parameters of the deaerator include: the length L of the deaerator water tank d , the radius R of the water tank d ; The real-time operation data of the unit includes: the working medium pressure p in the deaerator d , the feed water mass flow rate D at the inlet of the deaerator fw,in and specific enthalpy h fw,in , the feed water mass flow rate D at the outlet of the deaerator fw,out , the drain water mass flow rate D at the outlet of the steam-water separation and reheater dw,msr and specific enthalpy h of the drain water at the outlet of the steam-water separation and reheater dw,msr , the drain water mass flow rate D at the outlet of the high-pressure feed water heater dw,hr and specific enthalpy h dw,hr , the main steam pressure p ms and specific enthalpy h ms .

3. The real-time determination method of the extraction steam mass flow rate of the deaerator in a nuclear power plant according to claim 1, wherein In S6, iteratively calculate S4 - S5 until the difference between the simulation values of the extraction steam flow rates obtained in two adjacent times is less than a preset threshold, and terminate the calculation. The termination condition is: ||D es (i)-D es (i - 1)||2 < ε es where D es (i) represents the extraction steam mass flow obtained from the i-th iterative calculation, kg / s; ε es is a pre-set threshold value, kg / s.

4. A readable medium, characterized in that, Instructions are stored on the readable medium, and when the instructions are executed on an electronic device, the electronic device executes the method for real-time determination of the extraction steam mass flow rate of the deaerator of a nuclear power plant according to any one of claims 1 to 3.

5. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it is used to execute the method for real-time determination of the extraction steam mass flow rate of the deaerator of a nuclear power plant according to any one of claims 1 to 3.

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