RT-LAB based semi-physical simulation system for furnace water wall

Abstract

The application discloses a furnace water-cooled wall simulation system based on RT-LAB and mechanism modeling, relates to the technical field of coal-fired furnace simulation, and is a coal-fired boiler furnace simulation system with high precision, strong adaptability and good predictability, which can simulate the adverse effects of the DCS boiler control system abnormality on the operation of the boiler water-cooled wall through real-time simulation and test research, solves the problem that the current coal-fired boiler cannot accurately simulate the working condition of a major abnormal accident, and provides platform support and theoretical basis for the information security protection of the DCS control system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal-fired furnace simulation, in particular to a furnace water-cooled wall simulation system based on RT-LAB and mechanism modeling. BACKGROUND

[0002] The coal-fired boiler is a boiler that uses coal as fuel, which is a heat energy power equipment that heats the heat medium water or other organic heat carriers (such as heat conducting oil, etc.) to a certain temperature (or pressure) through the heat released by the combustion of coal in the furnace.

[0003] In the coal-fired boiler, the heat of coal is converted into steam or hot water, but not all of the heat is effectively converted, and a part of the heat is consumed without work, so there is an efficiency problem. Generally, larger coal-fired boilers have higher efficiency, between 60% and 80%. Coal-fired boilers are mainly classified according to their uses, which include coal-fired water boiler (for supplying boiled water), coal-fired hot water boiler (for heating and bathing), coal-fired steam boiler (for supplying steam), coal-fired heat conducting oil boiler (for cooking and drying), etc.

[0004] The water-cooled wall is the main heated part of the boiler, which is composed of several rows of steel pipes distributed around the boiler furnace. Its interior is flowing water or steam, and the outside receives the heat of the boiler furnace flame. It mainly absorbs the radiant heat of the high-temperature combustion products in the furnace, and the working medium rises in it and is heated and evaporated. The main monitoring method of the heat absorption of the working medium in the water-cooled wall of the coal-fired power plant is to reverse the total heat release of the furnace through the unit load and the coal-electricity conversion efficiency, and then to convert the total heat release into the heat absorption of the working medium in the water-cooled wall according to a certain proportion (usually 45-50%), that is, the efficiency of the water-cooled wall is the key to guarantee the normal operation of the boiler.

[0005] There are also some technical solutions in the prior art for studying the efficiency of the boiler water cooling wall and related problems based on model simulation, such as the Chinese patent for invention with the publication number CN104122291A, the publication date of October 29, 2014, and the name of "Real-time identification method for heat transfer rate of water cooling wall of ultra-supercritical thermal power unit to working medium", which provides a real-time identification method for heat transfer rate of water cooling wall of ultra-supercritical thermal power unit to working medium. The specific steps of the method include: 1: According to the boiler operation design regulation, the structure parameter database of the water cooling wall is established, and the related real-time data is read from the real-time database of the plant-level monitoring information system; 2: According to the working medium property parameter library, the property parameters of the working medium in the water cooling wall at a given time are calculated in real time combined with the server information of the field plant-level monitoring information system; 3: The heat transfer rate of each segment of the water cooling wall to the working medium is obtained from the water cooling wall working medium mass, energy and momentum dynamic balance calculation model, and the total heat transfer rate of the water cooling wall to the working medium is obtained after adding. The water cooling wall heat transfer rate is an important representation of the combustion condition and the coking degree in the furnace, which can be used for combustion state monitoring, low-nitrogen combustion and intelligent blowing control, and can also be used for online identification of the calorific value of the coal entering the furnace and online estimation of the boiler efficiency. However, the prior art still lacks a high-precision, high-adaptability and good-predictability coal-fired boiler water cooling wall simulation system, so as to realize accurate simulation of the coal-fired boiler and study the influence of various abnormal conditions on the operation of the coal-fired boiler in industrial application. SUMMARY

[0006] The purpose of the present application is to provide a high-precision, high-adaptability and good-predictability coal-fired boiler furnace simulation system, which can simulate the abnormal conditions of the DCS boiler control system in real time and test the possible adverse effects on the operation of the boiler water cooling wall, solve the problem that the major abnormal accident conditions of the coal-fired boiler cannot be accurately simulated at present, and provide platform support and theoretical basis for the information security protection of the DCS control system.

[0007] The purpose of the present application is achieved by the following technical solutions:

[0008] By connecting part of the real object in the system, the semi-physical simulation system can test the components in an environment that meets the overall performance indicators of the system, which is a necessary means to improve the reliability and development quality of the system design. The semi-physical simulation system of the coal-fired furnace based on RT-LAB includes an RT-Lab simulation platform, a DCS control system of the coal-fired furnace, and a host computer with a Simulink soft simulation model. The RT-Lab simulation platform is connected to the host computer data through TCP / IP protocol, and the DCS control system is connected to the RT-Lab simulation platform data through a data interface as the real part of the semi-physical simulation system.

[0009] The host is connected with the RT-Lab simulation platform data through TCP / IP protocol, the Simulink soft simulation model includes a zero-dimensional water cooling wall model, a one-dimensional water cooling wall model and an output result switching module; the RT-Lab simulation platform includes a model compilation module, a real-time simulation module and an interface module, the model compilation module receives model data from the host, and generates a program suitable for the RT-LAB simulation platform running after adding an opal series module, compiling and loading, the real-time simulation platform carries out real-time simulation after receiving the program generated by the model compilation module, realizes the rapid control prototype and the hardware-in-the-loop, meanwhile, the real-time simulation module is connected with the DCS control system through the interface module, the real-time simulation module receives logic signals and data signals from the DCS control system, and the DCS control system receives water cooling wall pressure, steam-water separator pressure and steam-water separator outlet temperature signals from the RT-Lab simulation platform.

[0010] Preferably, the logic signals include model switching signals, and the data signals include coal supply amount, primary air pressure, secondary air pressure and induced draft fan air pressure signals.

[0011] Further, the DCS control system includes a field control level subsystem, a process control level subsystem and a process management level subsystem; the field control level subsystem is used for data acquisition and pretreatment of process non-controlled variables; the process control level subsystem realizes the adjustment of the field production process by implementing various control logics, and is a core part of the DCS system; the process management level subsystem is a core display, operation and management device of the DCS control system, and is used for information input and acquisition, that is, a platform for information exchange between the operator and the DCS control system.

[0012] More specifically, after receiving the water cooling wall pressure, steam-water separator pressure and steam-water separator outlet temperature signals from the RT-Lab simulation platform, the process control level subsystem controls the water cooling wall temperature by adjusting the coal supply amount and air pressure through PID negative feedback control on one hand, and judges the change rate and accuracy requirement of the water cooling wall pressure, steam-water separator pressure and steam-water separator outlet temperature signals on the other hand.

[0013] If the change rate of the signals is fast and exceeds the set threshold value, the output result switching module switches the output result to the signal of the zero-dimensional water cooling wall model and outputs to the RT-Lab simulation platform; if the simulation software needs to output a result with high accuracy and in accordance with the set accuracy threshold value, the output result switching module switches the output result to the signal of the one-dimensional water cooling wall model and outputs to the RT-Lab simulation platform.

[0014] And, the one-dimensional water-cooled wall model is based on the phase change rule of the working medium in the pipe of the once-through boiler water-cooled wall during operation, and the water-cooled wall is divided into a hot water section, an evaporation section and a micro-superheating section with the phase change points as the demarcations, and each section is modeled based on the lumped parameter method;

[0015] The energy conservation equation of the hot water section is ,

[0016] The energy conservation equation of the evaporation section is ,

[0017] The momentum conservation equation of the micro-superheating section is ,

[0018] In the formula, A is the inner surface area of the water-cooled wall per unit length; l is the length; , h , u , D , T respectively represent density, enthalpy, thermodynamic energy, flow rate, temperature, and the subscript a , b , c respectively represent the hot water section, the evaporation section and the micro-superheating section, and the numerical subscript "0", "1", "2" and "3" respectively represent the 1, 2, 3 and 4 phase change point nodes in Figure 2 , Q represents heat, and the subscript n represents the heat transfer amount of the metal pipe wall to the working medium, represents time.

[0019] The zero-dimensional water-cooled wall model is a single-node model simplified from the water-cooled wall model, and the energy conservation equation is .

[0020] In the formula, is the derivative of the water-cooled wall pressure with respect to time; is the inlet feed water flow rate of the water-cooled wall; is the outlet steam flow rate of the water-cooled wall; is the inlet feed water enthalpy; is the saturated steam enthalpy; is the heat absorption amount of the water-cooled wall; is the saturated steam density; is the derivative of the saturated steam pressure with respect to density; is the derivative of the saturated steam enthalpy with respect to pressure; A is the cross-sectional area of the water-cooled wall; l is the equivalent length of the water-cooled wall.

[0021] The output result switching module is used for determining the one-dimensional water cooling wall model result or the zero-dimensional water cooling wall model result output by the simulation software according to the model switching signal output by the hardware system.

[0022] Compared with the prior art, the technical scheme has the following innovative points and beneficial effects (advantages):

[0023] 1. The coal-fired boiler water cooling wall semi-physical simulation system based on the RT-LAB technology and mechanism modeling provided by the application combines the RT-LAB technology, divides the water cooling wall mechanism modeling into one-dimensional and zero-dimensional models, selects the mechanism model with the optimal comprehensive calculation time and calculation precision for simulation, and ensures the real-time performance and accuracy of the simulation system.

[0024] 2. The coal-fired boiler water cooling wall semi-physical simulation system based on the RT-LAB technology and mechanism modeling provided by the application is connected between the RT-LAB semi-physical simulation basic platform and the DCS control system of the coal-fired boiler to be tested through a hard-wired mode, the RT-LAB technology with strong real-time performance is applied for the first time, and a simulation test system is designed for the harm caused by the abnormal DCS control system to the actual coal-fired boiler water cooling wall operation.

[0025] 3. The simulation system of the coal-fired boiler water cooling wall based on the RT-LAB technology provided by the application simulates abnormal working conditions and accident working conditions that can occur in the coal-fired boiler through parameter abnormality, the data signal of the DCS control system of the coal-fired boiler in the actual process is used in the acquisition module, the result of the simulation system is closer to the actual conclusion, and the test result is helpful for improving the engineering design scheme. DETAILED DESCRIPTION

[0026] The foregoing and subsequent specific description of the application becomes clearer when read in conjunction with the following drawings, in which:

[0027] Figure 1 Fig. 1 is a schematic diagram of a water cooling wall model framework of the application;

[0028] Figure 2 Fig. 2 is a schematic diagram of a two-phase heated pipe physical model of the application with a moving boundary. DETAILED DESCRIPTION

[0029] The technical scheme for achieving the object of the application is further illustrated below through specific examples, and it should be noted that the technical scheme claimed by the application includes but is not limited to the following examples.

[0030] Fig. 1 is a schematic diagram of a water cooling wall model framework of the application; Figure 1As shown, the RT-LAB-based hardware-in-the-loop simulation system for coal-fired furnaces provided in this embodiment allows components to be tested in an environment that meets the overall performance indicators of the system by integrating a hardware-in-the-loop simulation system containing some physical components. Specifically, it includes an RT-Lab simulation platform, a DCS control system for the coal-fired furnace, and a host computer with a Simulink soft simulation model. The RT-Lab simulation platform is connected to the host computer via TCP / IP protocol, while the DCS control system, as the physical component of the hardware-in-the-loop simulation system, is connected to the RT-Lab simulation platform via a data interface.

[0031] The Simulink water-cooled wall model established by the host mainly includes a one-dimensional water-cooled wall model, a zero-dimensional water-cooled wall model, and an output switching module.

[0032] The design steps of the one-dimensional water-cooled wall model are as follows: based on the phase change phenomenon of the working fluid inside the tube of the once-through boiler water-cooled wall during operation, the water-cooled wall is divided into three sections: hot water section, evaporation section and micro-superheating section, with the phase change point as the boundary, and each section is modeled based on the lumped parameter method.

[0033] Specifically, the energy conservation equation for the hot water section is as follows:

[0034] ,

[0035] The energy conservation equation for the evaporation section is as follows:

[0036] ,

[0037] The momentum conservation equation for the micro-superheated section is as follows:

[0038] ,

[0039] In the formula, A The area of ​​the inner surface of the water-cooled wall tube per unit length; l For length; , h , u , D , T These represent density, enthalpy, thermodynamic energy, flow rate, and temperature, respectively, with subscripts. a , b , c These represent the hot water section, evaporation section, and slightly superheated section, respectively. The subscripts "0", "1", "2", and "3" indicate... Figure 2 The 1st, 2nd, 3rd, and 4th phase transition nodes in the diagram. Q Indicates heat, subscript n This indicates the heat transfer from the metal tube wall to the working fluid. Indicates time.

[0040] The zero-dimensional water cooling wall mechanism model design step is to simplify the water cooling wall model into a single node model, and an energy conservation equation is

[0041] ;

[0042] wherein is a derivative of the water cooling wall pressure with respect to time; is a water cooling wall inlet feed water flow; is a water cooling wall outlet steam flow; is an inlet feed water enthalpy value; is a saturated steam enthalpy value; is a water cooling wall heat absorption amount; is a saturated steam density; is a derivative of the saturated steam pressure with respect to density; is a derivative of the saturated steam enthalpy value with respect to pressure; A is a water cooling wall cross-sectional area; is a water cooling wall equivalent length.

[0043] The model switching module design step is that the simulation software determines the results of the one-dimensional water cooling wall model or the results of the zero-dimensional water cooling wall model according to a model switching signal output by a hardware system.

[0044] Further, the RT-LAB simulation platform includes a model compiling module, a real-time simulation module and an interface module, the model compiling module mainly receives model data from a host, and generates a program that can be run by the RT-LAB simulation platform through adding an opal series module after compiling and loading, the real-time simulation platform performs real-time simulation after receiving the program generated by the model compiling module, realizes the rapid control prototype and the hardware-in-the-loop, and the real-time simulation module transmits data with a DCS control system through the interface module, the real-time simulation module receives a logic signal and a data signal from the DCS control system, the logic signal includes a model switching signal, the data signal includes a coal feed amount, a primary air pressure, a secondary air pressure and an induced draft fan air pressure signal, and the DCS control system receives a water cooling wall pressure, a steam-water separator pressure and a steam-water separator outlet temperature signal from the RT-Lab simulation platform.

[0045] The DCS control system includes a field control level subsystem, a process control level subsystem and a process management level subsystem, the field control level subsystem mainly performs data acquisition and preprocessing on process non-controlled variables, the process control level subsystem adjusts a field production process by implementing various control logics, is a core part in the DCS system, and the process management level subsystem is a platform for an operator to exchange information with the DCS, and is a core display, operation and management device of the DCS.

[0046] And specifically, the process control level of the DCS control system mainly processes information that, after receiving the water wall pressure, the steam-water separator pressure and the steam-water separator outlet temperature signals from the RT-Lab simulation platform, on one hand, through PID negative feedback control, the water wall temperature is controlled by adjusting the coal supply amount and the air supply pressure, on the other hand, the change rate and the accuracy requirement of the water wall pressure, the steam-water separator pressure and the steam-water separator outlet temperature signals are judged, if the change rate of the signals is fast, the model switching processing module outputs the switching zero-dimensional water wall model signal to the RT-Lab simulation platform, if the simulation software needs to output high-precision results, the model switching processing module outputs the switching one-dimensional water wall model signal to the RT-Lab simulation platform.

[0047] The mechanism modeling in the embodiment is based on MATLAB Simulink software, and the model conversion is performed through Artemis software of RT-LAB, so as to realize the data transmission between the RT-LAB semi-physical simulation basic platform and the mechanism model of the water wall of the coal-fired boiler. The RT-LAB semi-physical simulation basic platform is connected with the DCS control system of the boiler to be tested through hard wiring, so as to realize the output of the control signal.

Claims

1. A coal-fired furnace semi-physical simulation system based on RT-LAB, characterized in that: The RT-Lab simulation platform is connected with the host computer through a TCP / IP protocol, and the DCS control system is connected with the RT-Lab simulation platform through a data interface. The host computer is connected with the RT-Lab simulation platform through a TCP / IP protocol, and the Simulink soft simulation model comprises a zero-dimensional water wall model, a one-dimensional water wall model and an output result switching module; the RT-Lab simulation platform comprises a model compiling module, a real-time simulation module and an interface module; the model compiling module receives model data from the host computer, and generates a program suitable for the RT-LAB simulation platform after adding an opal series module, compiling and loading; the real-time simulation platform performs real-time simulation after receiving the program generated by the model compiling module; meanwhile, the real-time simulation module is connected with the DCS control system through the interface module; the real-time simulation module receives logical signals and data signals from the DCS control system, and the DCS control system receives water wall pressure, steam-water separator pressure and steam-water separator outlet temperature signals from the RT-Lab simulation platform.

2. The RT-LAB based coal-fired furnace semi-physical simulation system of claim 1, wherein: The logical signals comprise a model switching signal, and the data signals comprise coal supply amount, primary air pressure, secondary air pressure and induced draft fan air pressure signals.

3. The RT-LAB based coal-fired furnace semi-physical simulation system according to claim 1 or 2, characterized in that: The DCS control system comprises a field control level subsystem, a process control level subsystem and a process management level subsystem; the field control level subsystem is used for data acquisition and preprocessing of process non-controlled variables; The process control level subsystem adjusts the field production process by implementing control logic; The process management level subsystem is a core display, operation and management device of the DCS control system, and is used for information input and acquisition.

4. The RT-LAB based coal-fired furnace hardware-in-the-loop simulation system of claim 3, wherein: After receiving the water wall pressure, steam-water separator pressure and steam-water separator outlet temperature signals from the RT-Lab simulation platform, the process control level subsystem controls the water wall temperature by PID negative feedback control through adjusting the coal supply amount and air pressure; on the other hand, the process control level subsystem judges the change rate and accuracy requirement of the water wall pressure, steam-water separator pressure and steam-water separator outlet temperature signals.

5. The RT-LAB based coal-fired furnace hardware-in-the-loop simulation system of claim 3, wherein: If the change rate of the signals exceeds a set threshold value, the output result switching module switches the output result to the signal of the zero-dimensional water wall model and outputs the signal to the RT-Lab simulation platform; If the output precision of the simulation software needs to meet the set precision threshold value, the output result switching module switches the output result to the signal of the one-dimensional water wall model and outputs the signal to the RT-Lab simulation platform.

6. The RT-LAB based coal-fired furnace hardware-in-the-loop simulation system of claim 1, wherein: The one-dimensional water wall model is based on the phase change rule of the working medium in the water wall of the once-through boiler during operation, and divides the water wall into a hot water section, an evaporation section and a slightly superheated section according to the phase change point; and each section is modeled based on the lumped parameter method. The energy conservation equation of the hot water section is , The energy conservation equation for the evaporation section is , The momentum conservation equation of the micro-superheat section is , wherein is the inner surface area of the water wall tube per unit length; is the length; , , , , denote density, enthalpy, thermodynamic energy, flow rate, temperature, respectively, and the subscript , , denote the hot water section, the evaporation section, the slightly superheated section, respectively, and the numerical subscript "0", "1", "2", "3" denote each phase change point node, denotes heat, and the subscript denotes the heat transfer amount from the metal tube wall to the working medium, denotes time.

7. The RT-LAB based coal-fired furnace hardware-in-the-loop simulation system of claim 3, wherein: The zero-dimensional water-cooled wall model is a single-node model, and an energy conservation equation is , wherein is a derivative of water-cooled wall pressure with respect to time; is a water-cooled wall inlet feedwater flow rate; is a water-cooled wall outlet steam flow rate; is an inlet feedwater enthalpy value; is a saturated steam enthalpy value; is a water-cooled wall heat absorption amount; is a saturated steam density; is a derivative of saturated steam pressure with respect to density; is a derivative of saturated steam enthalpy value with respect to pressure; is a water-cooled wall cross-sectional area; and is a water-cooled wall equivalent length.

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