Nuclear power plant secondary loop steam humidity on-line measuring device and method based on big data

Abstract

The present application relates to the technical field of heat system monitoring and control, and particularly relates to a nuclear power secondary loop steam humidity online measuring device and method based on big data. The device comprises a measuring unit and a big data coupled adaptive control system. The measuring unit comprises a sampling steam inlet section, a steam heating section and a steam outlet section connected in sequence. An inlet temperature sensor is arranged at the inlet of the steam sampling inlet section. The steam heating section is configured with a spiral electric heating sheet for uniform heating, which is connected with a power meter, an outlet temperature sensor and a pressure sensor. The steam outlet section is connected with a mass flow meter and an exhaust valve. The big data coupled adaptive control system collects and processes data of each sensor, the power meter and the mass flow meter, controls the electric heating sheet and calculates the humidity measurement result, which comprises a big data processing unit and an adaptive PID controller. The present application introduces big data technology to improve the accuracy, sensitivity and real-time performance of humidity measurement, so as to effectively cope with the influence of humidity change on system stability and efficiency during the operation of a nuclear power plant.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal system monitoring and control, and particularly relates to a nuclear power two-loop steam humidity online measurement device and method based on big data. BACKGROUND

[0002] Nuclear power is one of the representatives of clean energy, and its stability and safety of operation are directly related to the reliability of energy supply. The turbine inlet of a nuclear power plant usually uses saturated steam, and the presence of humidity is the main cause of blade water erosion, which not only threatens the safe operation of the turbine, but also reduces the efficiency of the flow-through part. During the operation of a nuclear power plant, accurate measurement of steam humidity is crucial for maintaining the stability of the reactor and improving efficiency. Currently, nuclear power plants mainly rely on traditional humidity measurement methods, including thermodynamic method, chemical method, optical method, ultrasonic wave method, microwave resonant cavity perturbation method, capacitance method, Bragg fiber grating method and surface plasmon resonance method. Although these methods can provide reliable measurement results under certain conditions, they have problems such as measurement accuracy being easily affected by environmental conditions, response speed being relatively slow, and real-time monitoring of system humidity changes being difficult to achieve. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a nuclear power two-loop steam humidity online measurement device and method based on big data, which improves the accuracy, sensitivity and real-time performance of humidity measurement by introducing big data technology, to effectively cope with the influence of humidity changes on system stability and efficiency during the operation of a nuclear power plant.

[0004] The present application provides a nuclear power two-loop steam humidity online measurement device based on big data, comprising: a measurement unit and a big data coupled adaptive control system.

[0005] The measurement unit comprises a sampling steam inlet section, a steam heating section and a steam outlet section connected in sequence.

[0006] An inlet temperature sensor is arranged at the inlet of the steam sampling inlet section.

[0007] A spiral-shaped electric heating sheet with uniform heating is arranged in the steam heating section, which is connected to a power meter, an outlet temperature sensor and a pressure sensor.

[0008] A mass flow meter and an exhaust valve are connected in the steam outlet section.

[0009] The big data coupled adaptive control system collects and processes data of each sensor, power meter and mass flow meter, controls the electric heating sheet and calculates the humidity measurement result, which comprises a big data processing unit and an adaptive PID controller.

[0010] In one specific embodiment of the present invention, the measuring unit is made of heat-insulating pipe material.

[0011] In one specific embodiment of the present invention, the steam heating section is covered with a layer of silica aerogel felt.

[0012] In one specific embodiment of the present invention, the inner diameter of the steam heating section is 2-3 times the inner diameter of the sampling steam inlet section.

[0013] In one specific embodiment of the present invention, the outlet temperature sensor and pressure sensor of the steam heating section are disposed on the pipe wall near the tail of the spiral electric heating plate and are located at the two ends of the same cross-sectional circle diameter.

[0014] In one specific embodiment of the present invention, the big data processing unit stores historical operating data of wet steam, trains the steam humidity and temperature distribution model, establishes the steam humidity and temperature distribution model of the unit under different loads and in different equipment, and expands and updates the database and filters out bad points as the number of uses increases; the big data processing unit has the function of online retrieval of real-time data, and obtains the current real-time operating load data of the power system through the corresponding interface or communication protocol.

[0015] In one specific embodiment of the present invention, the electric heating element is heated by a heating power supply, and the adaptive PID controller determines the predicted humidity and heating power range by combining the operating load data, controls and adjusts the voltage of the heating power supply to perform controlled heating, collects data from various sensors after heating, and calculates the humidity.

[0016] In one specific embodiment of the present invention, the big data coupled adaptive control system further includes a fault early warning and diagnosis module, a data display module, and an intelligent report generation module.

[0017] This invention also provides a method for online measurement of steam humidity in the secondary loop of nuclear power plants based on big data, including the following steps:

[0018] Step 1: The sampled wet saturated steam enters the inlet section of the device, and the inlet temperature T1 is measured at the inlet.

[0019] Step 2: The big data coupled adaptive control system retrieves real-time operating load data for analysis, identifies the possible working equipment of the steam to be tested, calculates and predicts the humidity and heating power range based on the historical operating data of the working equipment, obtains the average power and the maximum power within the range, and uses the power supply voltage to adjust the control heating; by analyzing the temperature and pressure of the steam after heating, it is determined whether the steam has reached a superheated state under the two voltage adjustment heating conditions.

[0020] If both of the two steam are not superheated, then the predicted humidity and heating power range are calculated again according to the historical operation data of the working device, the heating is adjusted, and the comparison result is calculated;

[0021] If both of the two steam are superheated, then whether the humidity results under the two voltages are consistent is calculated respectively;

[0022] If consistent, the humidity result is output and the database is updated;

[0023] If inconsistent, within the calculation upper limit times, other possible working devices are re-locked, the historical operation data is recalled to predict the data again and adjust the heating power to calculate and compare; when the upper limit of the calculation times is reached, the superheat degree of 10℃ is set by default to heat, and the controller judges whether the steam is superheated according to the data after heating to execute heating or calculate the humidity result command.

[0024] In a specific embodiment of the present application, the calculation method of the humidity in step S2 is:

[0025] 1) According to the inlet temperature T1 measured at the inlet, the saturated gas phase enthalpy h" and the saturated liquid phase enthalpy h' are obtained, and the mass flow rate G is calculated to obtain the inlet enthalpy value of the saturated steam:

[0026]

[0027] In the formula: is the inlet enthalpy value of the saturated steam, kW; y is the humidity to be solved; h' is the saturated liquid phase enthalpy; h" is the saturated gas phase enthalpy; G is the mass flow rate of the steam;

[0028] 2) According to the temperature T2 and the pressure P of the superheated steam, the specific enthalpy h2 of the superheated steam is obtained, and the enthalpy value of the superheated steam is calculated:

[0029]

[0030] In the formula: is the enthalpy value of the superheated steam; h2 is the specific enthalpy of the superheated steam; G is the mass flow rate of the steam;

[0031] 3) Since the heat absorption process of the steam in the heating section satisfies the following energy conservation:

[0032]

[0033] In the formula: is the heat absorption amount of the steam, kW; is the heat dissipated by the wet steam to the outside in this process; is the change amount of the enthalpy value of the wet steam; MgΔh is the potential energy of the wet steam; is the work done by the wet steam to the outside before and after heating; is the kinetic energy of the wet steam;

[0034] 4) Since in the device, the wet steam heat absorption process can be regarded as zero heat loss, zero external work, zero potential energy change, so:

[0035]

[0036] The energy conservation equation can be simplified as:

[0037] That is

[0038] 5) The above formula is substituted into:

[0039] h2G=[yh'+(1-y)h”]G+UI

[0040] The humidity y of the wet steam is calculated:

[0041]

[0042] In the formula: h2 is the specific enthalpy of superheated steam, kJ / kg; G is the mass flow of steam; y is the humidity to be solved; h' is the enthalpy of saturated liquid phase; h'' is the enthalpy of saturated gas phase; UI is the heating power. Compared with the prior art, the nuclear power two-loop steam humidity online measurement device and method based on big data have the following beneficial effects:

[0043] (1) By integrating big data technology, a large amount of historical data and operation data are used for pattern recognition and prediction, and the measurement accuracy is improved;

[0044] (2) According to the continuously updated big data information, the control strategy of steam humidity measurement can be dynamically adjusted, so that the measurement device can automatically optimize the operation under various working conditions, and the measurement precision is improved;

[0045] (3) Real-time online monitoring of nuclear power plant two-loop steam humidity is realized, and the operator can timely understand the change of steam quality, which is crucial for maintaining the operation efficiency of the steam turbine and avoiding the corrosion problem caused by high steam humidity. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 Fig. 1 shows a schematic diagram of a nuclear power two-loop steam humidity online measurement device based on big data;

[0047] Figure 2 Fig. 3 shows a control flow diagram of a big data coupling adaptive control system of a nuclear power two-loop steam humidity online measurement device based on big data;

[0048] In the figure, 1, steam inlet section; 2, steam heating section; 3, heat-insulating pipe material; 4, silica aerogel felt pad; 5, spiral electric heating sheet; 6, waterproof insulating bolt; 7, outlet temperature sensor; 8, steam outlet section; 9, mass flow meter; 10, exhaust valve; 11, inlet temperature sensor; 12, heating power supply; 13, power meter; 14, big data coupling adaptive control system; 15, adaptive PID controller; 16, big data processing unit; 17, pressure sensor. DETAILED DESCRIPTION

[0049] In order to further understand the present application, the embodiments of the present application are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, but not for limiting the present application.

[0050] The embodiments of the present application disclose a big data-based nuclear power secondary loop steam humidity online measurement device, as shown in the figure, comprising a measurement unit and a big data coupling adaptive control system 14; Figure 1

[0051] The measurement unit comprises a sampling steam inlet section 1, a steam heating section 2 and a steam outlet section 8 connected in sequence;

[0052] The measurement unit adopts a heat-insulating pipe material 3;

[0053] The steam heating section 2 is wrapped with a layer of silica aerogel felt pad 4;

[0054] The inner diameter of the steam heating section 2 is 2-3 times of the inner diameter of the sampling steam inlet section 1;

[0055] An inlet temperature sensor 11 is arranged at the inlet of the steam sampling inlet section 1;

[0056] A spiral electric heating sheet 5 for uniform heating is arranged in the steam heating section 2, which is connected with a power meter 13, an outlet temperature sensor 7 and a pressure sensor 17;

[0057] Both ends of the spiral electric heating sheet 5 are connected with a heating power supply 12 and fixed by a waterproof insulating bolt 6 on the pipe wall.

[0058] The spiral electric heating sheet 5 can provide high-efficiency heating effect. The spiral structure can strengthen the heat exchange disturbance, help to increase the heat exchange area, improve the heating efficiency, reduce the heating loss, so as to realize the change of steam heat absorption by adjusting the electric heating power, and more effectively realize the measurement of steam humidity.

[0059] The outlet temperature sensor 7 and the pressure sensor 17 of the steam heating section 2 are arranged on the pipe wall close to the tail of the spiral electric heating sheet 5 and located at both end points of the same cross-sectional circle diameter. ​

[0060] A mass flow meter 9 and an exhaust valve 10 are connected in the steam outlet section 8;

[0061] The big data coupling adaptive control system 14 collects and processes data of each sensor, the power meter 13 and the mass flow meter 9, realizes control of the electric heating sheet 5 and calculates humidity measurement results, which includes a big data processing unit 16 and an adaptive PID controller 15.

[0062] The big data processing unit 16 includes a database, a data processing module, a data acquisition module, a steam humidity and temperature distribution model;

[0063] The database stores historical operation data of wet steam, trains the steam humidity and temperature distribution model, establishes the steam humidity and temperature distribution model of the unit under different loads and in different equipment, and updates and filters out bad points as the number of uses increases; the big data processing unit 16 has the function of online retrieval of real-time data, and obtains real-time operation load data of the current power system through a corresponding interface or communication protocol. The data processing module reads and processes the implementation data to obtain data that can be trained / calculated.

[0064] The electric heating sheet is controlled by a heating power source, the adaptive PID controller determines the predicted humidity and the heating power range in combination with the operation load data, controls and adjusts the voltage of the heating power source to control the heating, collects the data of each sensor after heating, and calculates the humidity.

[0065] The big data coupling adaptive control system 14 further includes a fault early warning and diagnosis module, a data display module, and an intelligent report generation module.

[0066] The fault early warning and diagnosis module can use big data analysis to find the trend of abnormal change of steam humidity in advance, realize fault early warning, shorten the fault response time, reduce unplanned downtime, and prolong the service life of the equipment.

[0067] The data display module and the intelligent report generation module provide clear decision-making basis for maintenance personnel through data visualization and intelligent reports, simplify the operation and maintenance process, reduce operation and maintenance costs, and improve the overall management level.

[0068] The specific working process of the big data coupled adaptive control system 14 is as follows: the inlet temperature sensor 11 transmits the inlet temperature of the wet steam to be measured to the adaptive PID controller 15, the adaptive PID controller 15 determines the predicted humidity and the heating power range in combination with the real-time operating load data provided by the big data processing unit 16, and adjusts the voltage of the heating power supply 12 to control the heating according to the average power and the maximum power in the range; the collected sensor data after heating is compared to determine whether the actual humidity results calculated under the two voltages are consistent to correct the heating power supply 12 until the adaptive PID controller 15 calculates the accurate result.

[0069] In the big data coupled adaptive control system 14, the humidity of the working steam in different devices has a certain range value respectively, when the load changes, the working steam temperature of each device will change correspondingly, and the humidity range is relatively stable, therefore, the big data processing unit 16 determines the working device of the steam to be measured according to the established steam temperature and humidity distribution model, so as to determine the humidity change range for reasonable prediction; if the calculation result does not meet the output condition all the time and has exceeded the upper limit of system calculation, the heating power supply 12 heats according to the default superheat degree of 10 DEG C of the inlet temperature of the steam to be measured, and the adaptive PID controller 15 judges whether the steam is overheated according to the data after heating to execute heating or calculate the humidity result command.

[0070] The present application can accurately identify the working device of the steam to be measured by establishing the humidity and temperature distribution model of the steam under different loads, so as to more accurately predict the humidity change range, and the result calculated by the controller each time is compared with the calculation result under the maximum heating power, so as to realize the real-time online monitoring and checking of the humidity, and improve the efficiency and precision of the humidity measurement.

[0071] The big data processing unit used in the present application has the function of online retrieval of real-time data, which can more accurately determine the prediction range of humidity by obtaining the real-time operating load data of the current power system, realize real-time regulation and control of heating power, and update the database with the increase of the use frequency, so that the system can better adapt to different working conditions and load changes.

[0072] The embodiment of the present application also discloses a big data-based online measurement method for the steam humidity in the secondary loop of a nuclear power plant, as shown in the figure, comprising the following steps: Figure 2 The specific working process of the big data coupled adaptive control system 14 is as follows: the inlet temperature sensor 11 transmits the inlet temperature of the wet steam to be measured to the adaptive PID controller 15, the adaptive PID controller 15 determines the predicted humidity and the heating power range in combination with the real-time operating load data provided by the big data processing unit 16, and adjusts the voltage of the heating power supply 12 to control the heating according to the average power and the maximum power in the range; the collected sensor data after heating is compared to determine whether the actual humidity results calculated under the two voltages are consistent to correct the heating power supply 12 until the adaptive PID controller 15 calculates the accurate result.

[0073] Step 1: The sampled wet saturated steam enters the inlet section of the device, and the inlet temperature T1 is measured at the inlet;

[0074] Step 2: The big data coupling adaptive control system calls real-time operating load data for analysis, locks the possible working equipment of the steam to be measured, calculates the predicted humidity and heating power range according to the historical operating data of the working equipment, obtains the average power and the maximum power in the range for adjusting the power supply voltage to control the heating; by analyzing the temperature and pressure of the steam after heating, it is judged whether the steam reaches the superheated state under the condition of two voltage adjustment heating;

[0075] If neither of the two steam is superheated, then recalculate the predicted humidity and heating power range according to the historical operating data of the working equipment, adjust the heating and calculate the comparison results;

[0076] If both of the two steam are superheated, then calculate whether the humidity results under the two voltages are consistent;

[0077] If consistent, output the humidity result and update the database;

[0078] If inconsistent, within the calculation upper limit, re-lock other possible working equipment, recalculate the data and adjust the heating power to calculate and compare the results; if the calculation upper limit is reached, the default heating is set to 10℃ superheat degree, and the controller judges whether the steam is superheated after heating to execute heating or calculate the humidity result command.

[0079] The calculation method of the humidity is:

[0080] 1) According to the measured inlet temperature T1 at the inlet, the saturated gas phase enthalpy h" and the saturated liquid phase enthalpy h' are obtained, and the mass flow rate G is calculated to obtain the inlet enthalpy value of the saturated steam:

[0081]

[0082] In the formula: is the inlet enthalpy value of the saturated steam, kW; y is the humidity to be solved; h' is the saturated liquid phase enthalpy, kJ / kg; h" is the saturated gas phase enthalpy, kJ / kg; G is the mass flow rate of the steam, kg / s;

[0083] 2) According to the temperature T2 and pressure P of the superheated steam, the specific enthalpy h2 of the superheated steam is obtained, and the enthalpy value of the superheated steam is calculated:

[0084]

[0085] In the formula: is the enthalpy value of the superheated steam, kW; h2 is the specific enthalpy of the superheated steam, kJ / kg; G is the mass flow rate of the steam, kg / s;

[0086] 3) The heat absorption process of the steam in the heating section satisfies the following energy conservation:

[0087]

[0088] In the formula: Q is the heat absorbed by the steam, kW; Q is the heat dissipated by the wet steam, kW; MgΔh is the potential energy of the wet steam, kW; W is the work done by the wet steam, kW; MgΔh is the potential energy of the wet steam, kW;

[0089] 4) Since the wet steam heat absorption process in the device can be regarded as zero heat loss, zero external work, and zero potential energy change, so:

[0090]

[0091] The energy conservation equation can be simplified as:

[0092] That is

[0093] 5) The above formula is substituted into:

[0094] h2G=[yh'+(1-y)h”]G+UI

[0095] Calculate the humidity y of the wet steam:

[0096]

[0097] In the formula, h2 is the specific enthalpy of the superheated steam, kJ / kg; G is the mass flow rate of the steam, kg / s; y is the humidity to be calculated; h' is the saturated liquid phase enthalpy, kJ / kg; h" is the saturated gas phase enthalpy, kJ / kg; and UI is the heating power, kW.

[0098] The present application has significant practical value, which not only improves the safety and reliability of the operation of the nuclear power plant, but also helps to realize more refined operation management, and meets the development trend of intelligent management of modern nuclear power plants.

[0099] The above examples are only used to help understand the method of the present application and its core idea. It should be noted that for ordinary skilled in the art, without departing from the principles of the present application, the present application can be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present application.

[0100] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A nuclear power plant secondary loop steam humidity online measurement device based on big data, characterized in that, include: Measurement unit and big data coupled adaptive control system (14); The measuring unit includes a sampling steam inlet section (1), a steam heating section (2), and a steam outlet section (8) connected in sequence; An inlet temperature sensor is installed at the inlet of the steam sampling inlet section (1); The steam heating section (2) is equipped with a spiral electric heating element (5) that heats uniformly, and is connected to a power meter, an outlet temperature sensor and a pressure sensor. A mass flow meter (9) and an exhaust valve (10) are connected inside the steam outlet section (8); The big data coupled adaptive control system (14) collects and processes data from various sensors, power meters and mass flow meters to control the electric heating element and calculate the humidity measurement result. It includes a big data processing unit (16) and an adaptive PID controller (15). The big data processing unit (16) stores historical operating data of wet steam, trains the steam humidity and temperature distribution model, establishes the steam humidity and temperature distribution model of the unit under different loads and in different equipment, and expands and updates the database and filters out bad points as the number of uses increases; the big data processing unit (16) has the function of online retrieval of real-time data, and obtains the current real-time operating load data of the power system through the corresponding interface or communication protocol; The electric heating element is heated by a heating power supply. The adaptive PID controller combines the operating load data to determine the predicted humidity and heating power range, controls and adjusts the voltage of the heating power supply to perform controlled heating, collects data from various sensors after heating, and calculates the humidity.

2. The online measurement device for steam humidity in the secondary loop of nuclear power plants based on big data as described in claim 1, characterized in that, The measuring unit uses heat-insulating pipe material.

3. The online measurement device for steam humidity in the secondary loop of nuclear power plants based on big data as described in claim 2, characterized in that, The steam heating section is covered with a layer of silica aerogel felt.

4. The online measurement device for steam humidity in the secondary loop of a nuclear power plant based on big data as described in claim 1, characterized in that, The inner diameter of the steam heating section (2) is 2-3 times the inner diameter of the sampling steam inlet section (1).

5. The online measurement device for steam humidity in the secondary loop of a nuclear power plant based on big data as described in claim 1, characterized in that, The outlet temperature sensor (7) and pressure sensor (17) of the steam heating section (2) are located on the pipe wall near the tail of the spiral electric heating element (5) and at the two ends of the same cross-sectional circle diameter.

6. The online measurement device for steam humidity in the secondary loop of nuclear power plants based on big data as described in claim 1, characterized in that, The big data coupled adaptive control system also includes a fault early warning and diagnosis module, a data display module, and an intelligent report generation module.

7. A method for online measurement of steam humidity in the secondary loop of a nuclear power plant based on big data, using the online steam humidity measurement device of any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: The sampled wet saturated steam enters the inlet section of the device, and the inlet temperature T1 is measured at the inlet. Step 2: The big data coupled adaptive control system retrieves real-time operating load data for analysis, identifies the possible working equipment of the steam to be tested, calculates and predicts the humidity and heating power range based on the historical operating data of the working equipment, obtains the average power and the maximum power within the range, and uses the power supply voltage to adjust the control heating; by analyzing the temperature and pressure of the steam after heating, it is determined whether the steam has reached a superheated state under the two voltage adjustment heating conditions. If neither type of steam is overheated, the predicted humidity and heating power range are recalculated based on the historical operating data of the equipment, the heating is adjusted, and the comparison results are calculated. If both types of steam are overheated, calculate whether the humidity results under the two voltages are consistent. If they match, output the humidity result and update the database; If there is a discrepancy, within the maximum number of calculations, other possible working equipment will be locked, historical operating data will be retrieved to re-predict the data, and the heating power will be adjusted for calculation and comparison; if the maximum number of calculations is reached, the superheat of 10°C will be set by default for heating, and the controller will determine whether the steam is overheated based on the data after heating and execute the heating or humidity calculation command.

8. The method for online measurement of steam humidity in the secondary loop of nuclear power plants based on big data, as described in claim 7, is characterized in that... In step S2, the humidity is calculated as follows: 1) Based on the inlet temperature T1 measured at the inlet, obtain the saturated gas phase enthalpy h″ and saturated liquid phase enthalpy h′, and the mass flow rate G, calculate the inlet enthalpy of saturated steam: In the formula: y is the inlet enthalpy of saturated steam (kW); h′ is the enthalpy of saturated liquid phase; h″ is the enthalpy of saturated gas phase; G is the mass flow rate of steam. 2) Obtain the specific enthalpy h2 of the superheated steam based on its temperature T2 and pressure P, and calculate the enthalpy value of the superheated steam: In the formula: h1 is the enthalpy of superheated steam; h2 is the specific enthalpy of superheated steam; G is the mass flow rate of steam. 3) The heat absorption process of steam in the heating section satisfies the following energy conservation principle: In the formula: The heat absorbed by steam, in kW; This refers to the heat lost by the wet steam to the outside during this process; MgΔh represents the change in enthalpy of wet steam; MgΔh represents the potential energy of wet steam. The work done by the wet steam before and after heating; The kinetic energy of the wet steam; 4) Since the heat absorption process of wet steam in the device can be considered as having zero heat loss, zero external work done, and zero potential energy change, therefore: The law of conservation of energy can be simplified to: Right now 5) Substituting the above equations into the equation, we get: h2G=[yh'+(1-y)h”]G+UI Calculate the humidity y of wet steam: In the formula: h2 is the specific enthalpy of superheated steam, kJ / kg; G is the mass flow rate of steam; y is the humidity to be calculated; h′ is the enthalpy of saturated liquid phase; h″ is the enthalpy of saturated gas phase; UI is the heating power.

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