阅读说明：本技术 燃煤锅炉尾部对流换热器积灰在线监测系统及监测方法 (Dust deposition on-line monitoring system and monitoring method for convection heat exchanger at tail of coal-fired boiler ) 是由 周俊波 高林 李军 马俊喜 鲍教旗 安建军 贾国栋 王明坤 于 2019-09-16 设计创作，主要内容包括：本发明公开了一种燃煤锅炉尾部对流换热器积灰在线监测系统及监测方法,该系统包括DCS服务器、串口服务器、PLC和工控机,运行于DCS服务器上的虚拟DPU程序通过动态链接通讯接口程序与串口服务器相互间进行TCP/IP通讯,串口服务器另一端与积灰监测PLC通过MODBUS通讯连接；PLC包含电源模块、通讯模块和处理器模块,通讯模块与串口服务器相连,通过MODBUS协议进行数据间通讯,处理器模块与工控机通过网线连接,实现数据通讯,电源模块用于给PLC设备供电；工控机用于积灰监测程序调试和存储数据；处理器模块用于实时计算锅炉尾部对流换热器的积灰程度；本发明通过实时监测锅炉尾部对流换热器传热过程的强弱程度来表征换热器积灰程度。(The invention discloses an on-line monitoring system and a monitoring method for dust deposition of a convection heat exchanger at the tail part of a coal-fired boiler, wherein the system comprises a DCS (distributed control system) server, a serial server, a PLC (programmable logic controller) and an industrial personal computer, a virtual DPU (distributed data Unit) program running on the DCS server is in TCP/IP (transmission control protocol/Internet protocol) communication with the serial server through a dynamic link communication interface program, and the other end of the serial server is in communication connection with the dust deposition monitoring PLC through an MODBUS; the PLC comprises a power supply module, a communication module and a processor module, wherein the communication module is connected with the serial server and is used for carrying out data communication through an MODBUS protocol, the processor module is connected with the industrial personal computer through a network cable to realize data communication, and the power supply module is used for supplying power to the PLC equipment; the industrial personal computer is used for debugging the dust deposition monitoring program and storing data; the processor module is used for calculating the dust deposition degree of the convection heat exchanger at the tail part of the boiler in real time; the invention characterizes the dust deposition degree of the heat exchanger by monitoring the strength degree of the heat transfer process of the convection heat exchanger at the tail part of the boiler in real time.)

1. Coal fired boiler afterbody convection heat exchanger deposition on-line monitoring system, its characterized in that: the system comprises a DCS server, a serial server, a dust deposition monitoring PLC and an industrial personal computer which are connected in sequence;

The virtual DPU program running on the DCS server is in TCP/IP communication with the serial port server through a dynamic link communication interface program, and the DCS server transmits real-time process data of the running of the coal-fired thermal power generating unit to the soot monitoring PLC;

the system comprises a serial server, a DCS server, an MODBUS, a dust accumulation monitoring PLC and a communication gateway, wherein the serial server serves as a communication gateway from a serial interface to the Ethernet to realize bidirectional data transmission between the serial interface and the Ethernet interface;

the dust deposition monitoring PLC comprises a power supply module, a communication module and a processor module, wherein the communication module is connected with a serial server and is used for carrying out data communication through an MODBUS protocol, the processor module is connected with an industrial personal computer through a network cable to realize data communication, and the power supply module is used for supplying power to the dust deposition monitoring PLC;

The industrial personal computer is connected with a processor module of the dust deposition monitoring PLC and is used for debugging a dust deposition monitoring program and storing historical data;

The processor module is used for calculating the dust deposition degree of the convection heat exchanger at the tail of the coal-fired boiler in real time.

2. the real-time online monitoring method for the accumulated dust of the online monitoring system of the coal-fired boiler tail convection heat exchanger is characterized by comprising the following steps of: the method comprises the following steps:

step 1: the ash deposition monitoring PLC reads real-time process data from the DCS server, wherein the real-time process data comprises load of the coal-fired thermal power generating unit, water supply flow, inlet working medium temperature of the convection heat exchanger, inlet working medium pressure of the convection heat exchanger, outlet working medium temperature of the convection heat exchanger, outlet working medium pressure of the convection heat exchanger, inlet flue gas temperature of the convection heat exchanger, outlet flue gas temperature of the convection heat exchanger, main steam flow G of the boiler and reheating steam flow D;

step 2: the ash deposition monitoring PLC preprocesses the data of the coal-fired power generating unit in real time during operation, eliminates abnormal data and removes noise:

the dust deposition monitoring PLC selects m times of normal signals x for a certain real-time process data variable x read from the DCS server₁,x₂,…，x_mFor sample data, calculating an average value of the sample dataand standard deviation of

Reading current operation data x₀According to the discriminantjudging whether the current operation data is an abnormal value, if the judgment formula is true, taking x₀＝x_0-1+(x_0-1-x_0-2) Replacing the current value as the current normal operation data and storing; beta is an error coefficient, x_0-1、x_0-2Normal operation data stored in the previous two calculation periods;

GetPerforming next calculation as the smoothed data;

and step 3: calculating the enthalpy value i' of the working medium at the inlet of the heat exchanger and the enthalpy value i of the working medium at the outlet of the heat exchanger according to the working medium and the pressure at the inlet and the outlet of the heat exchanger;

and 4, step 4: and the processor module of the dust deposition monitoring PLC calculates a cleanliness characterization index CF of the convection heat exchanger at the tail of the coal-fired boiler based on the following formula.

c_metaland c_steamis the average specific heat capacity, m, of the metal tube of the heat exchanger and the working medium in the heat exchanger_metalAnd m_steamIs the mass of the metal tube of the heat exchanger and the working medium in the heat exchanger, T_metalis the average temperature of the metal tube wall of the heat exchanger, P_steamis the working medium pressure in the heat exchanger, t is the time, s; delta t is the heat transfer temperature and pressure of the heat exchanger, DEG C; d is the flow of the working medium in the heat exchanger, kg/s; i' is the enthalpy value of the working medium at the inlet of the heat exchanger, which is checked according to the temperature and the pressure of the working medium inlet, and kJ/kg; i' is the enthalpy value of the working medium at the outlet of the heat exchanger, which is checked according to the temperature and the pressure of the working medium outlet, kJ/kg; f is the area of the heat exchanger, m²；K_idealIs the ideal heat transfer coefficient of the heat exchanger, W/(m)²·℃)；

The quick load lifting of the unit causes deviation between the actual heat transfer capacity and the working medium heat absorption capacity of the convection heat exchanger at the tail of the coal-fired boiler, the first two items of the formula denominator consider the change of the heat storage of the heat exchanger caused by the metal temperature change of the heat exchanger and the change of the heat storage of the working medium caused by the steam pressure change, and a and b are corresponding correction coefficients respectively;

And 5: and (4) sending the result of the cleanliness characterization index calculation of the convection heat exchanger at the tail of the coal-fired boiler obtained in the step (4) to a DCS server through a communication module of the dust deposition monitoring PLC through a serial server for operators to perform dust blowing reference.

3. The real-time online monitoring method for the ash deposition according to claim 2, characterized in that: in the step 2, the sample data is selected to cover the main operation condition of the coal-fired thermal power generating unit, and the value m is more than or equal to 300.

Technical Field

the invention relates to the technical field of operation monitoring and optimization of coal-fired power station boilers, in particular to an online monitoring system and an online monitoring method for accumulated dust of a convection heat exchanger at the tail of a coal-fired boiler.

background

the boiler heat exchanger of the power station boiler has serious ash deposition and slag bonding phenomena easily caused by the poor quality of non-designed coal or power coal for combustion, and particularly the unit which combusts Xinjiang east Junggar coal faces serious ash deposition problems in the operation process. The ash and dirt deposited on the heat exchanger can block the heat on the smoke side from being transferred to the working medium side, so that the smoke temperature of the boiler is increased, and the efficiency of the boiler is reduced. Thicker ash can also form a flue gas corridor, which not only aggravates the local wear of the heat exchanger, but also causes steam temperature deviation, and brings a series of boiler operation problems.

at present, most of domestic coal-fired boilers are mainly provided with soot blowers such as steam soot blowers and sound wave soot blowers, and operators generally purge all heat exchangers in sequence according to a timing and quantitative principle so as to avoid serious soot deposition of the heat exchangers. The soot blowing mode assumes that the soot deposition and slag bonding degree of each heat exchanger of the boiler is linearly related to the operation time, and the difference of the actual soot growth of each heat exchanger is not considered, so that the soot blowing deficiency of the heat exchanger with serious soot deposition is probably caused, and the cleaner heat exchanger is excessively blown. The insufficient soot blowing causes a serious soot deposition problem, excessive blowing not only wastes soot blowing steam, but also causes blowing loss of the heat exchanger, and the service life of the heat exchanger is shortened.

Based on the reasons, the boiler heat exchanger ash and dirt real-time monitoring system and the monitoring method are established, the heat exchanger is blown in a targeted mode according to the real-time ash and dirt degree of the boiler heat exchanger, and it is important to blow ash as required.

The inside operating mode of operation boiler is abominable, adopts hardware equipment to monitor heat exchanger dirt degree such as heat-flow meter, high temperature imager not only hardware installation investment cost is high, and the later maintenance expense is big moreover to equipment failure can't be restoreed generally during the boiler operation. Based on the existing measuring points of the boiler or a small number of conventional measuring points, the real-time online monitoring of the dust and dirt of the heat exchangers of the boiler is realized by deeply excavating the operation data of the unit, and the realization of the 'dust blowing as required' of each heat exchanger of the boiler is an important link for realizing the visualization, digitization and intellectualization of the operation of the boiler.

disclosure of Invention

Aiming at the problems in the prior art, the invention provides an on-line monitoring system and a monitoring method for the dust deposition of a convection heat exchanger at the tail part of a coal-fired boiler, wherein the dust deposition degree of the heat exchanger is represented by monitoring the strength degree of the heat transfer process of the convection heat exchanger at the tail part of the boiler in real time.

In order to achieve the purpose, the invention adopts the following technical scheme:

The on-line monitoring system for the accumulated dust of the convection heat exchanger at the tail part of the coal-fired boiler comprises a DCS server, a serial server, an accumulated dust monitoring PLC and an industrial personal computer which are connected in sequence;

The virtual DPU program running on the DCS server is in TCP/IP communication with the serial port server through a dynamic link communication interface program, and the DCS server transmits real-time process data of the running of the coal-fired thermal power generating unit to the soot monitoring PLC;

The system comprises a serial server, a DCS server, an MODBUS, a dust accumulation monitoring PLC and a communication gateway, wherein the serial server serves as a communication gateway from a serial interface to the Ethernet to realize bidirectional data transmission between the serial interface and the Ethernet interface;

The dust deposition monitoring PLC comprises a power supply module, a communication module and a processor module, wherein the communication module is connected with a serial server and is used for carrying out data communication through an MODBUS protocol, the processor module is connected with an industrial personal computer through a network cable to realize data communication, and the power supply module is used for supplying power to the dust deposition monitoring PLC;

The industrial personal computer is connected with a processor module of the dust deposition monitoring PLC and is used for debugging a dust deposition monitoring program and storing historical data;

The processor module is used for calculating the dust deposition degree of the convection heat exchanger at the tail of the coal-fired boiler in real time.

The real-time online monitoring method for the accumulated dust of the on-line monitoring system of the convection heat exchanger at the tail of the coal-fired boiler comprises the following steps:

Step 1: the ash deposition monitoring PLC reads real-time process data from the DCS server, wherein the real-time process data comprises load of the coal-fired thermal power generating unit, water supply flow, inlet working medium temperature of the convection heat exchanger, inlet working medium pressure of the convection heat exchanger, outlet working medium temperature of the convection heat exchanger, outlet working medium pressure of the convection heat exchanger, inlet flue gas temperature of the convection heat exchanger, outlet flue gas temperature of the convection heat exchanger, main steam flow G of the boiler, reheating steam flow D and the like;

step 2: the ash deposition monitoring PLC preprocesses the data of the coal-fired power generating unit in real time during operation, eliminates abnormal data and removes noise:

The dust deposition monitoring PLC selects m times of normal signals x for a certain real-time process data variable x read from the DCS server₁,x₂,…，x_mFor sample data, calculating an average value of the sample dataand standard deviation of

reading current operation data x₀According to the discriminantJudging whether the current operation data is an abnormal value or not, if the judgment formula is true,Get x₀＝x_0-1+(x_0-1-x_0-2) Replacing the current value as the current normal operation data and storing; beta is an error coefficient, x_0-1、x_0-2Normal operation data stored in the previous two calculation periods;

GetPerforming next calculation as the smoothed data;

And step 3: calculating the enthalpy value i' of the working medium at the inlet of the heat exchanger and the enthalpy value i of the working medium at the outlet of the heat exchanger according to the working medium and the pressure at the inlet and the outlet of the heat exchanger;

and 4, step 4: and the processor module of the dust deposition monitoring PLC calculates a cleanliness characterization index CF of the convection heat exchanger at the tail of the coal-fired boiler based on the following formula.

c_metalAnd c_steamIs the average specific heat capacity, m, of the metal tube of the heat exchanger and the working medium in the heat exchanger_metalAnd m_steamis the mass of the metal tube of the heat exchanger and the working medium in the heat exchanger, T_metalis the average temperature of the metal tube wall of the heat exchanger, P_steamIs the working medium pressure in the heat exchanger, t is the time, s; delta t is the heat transfer temperature and pressure of the heat exchanger, DEG C; d is the flow of the working medium in the heat exchanger, kg/s; i' is the enthalpy value of the working medium at the inlet of the heat exchanger, which is checked according to the temperature and the pressure of the working medium inlet, and kJ/kg; i' is the enthalpy value of the working medium at the outlet of the heat exchanger, which is checked according to the temperature and the pressure of the working medium outlet, kJ/kg; f is the area of the heat exchanger, m²；K_idealis the ideal heat transfer coefficient of the heat exchanger, W/(m)²·℃)；

The quick load lifting of the unit causes deviation between the actual heat transfer capacity and the working medium heat absorption capacity of the convection heat exchanger at the tail of the coal-fired boiler, the first two items of the formula denominator consider the change of the heat storage of the heat exchanger caused by the metal temperature change of the heat exchanger and the change of the heat storage of the working medium caused by the steam pressure change, and a and b are corresponding correction coefficients respectively;

And 5: and (4) sending the result of the cleanliness characterization index calculation of the convection heat exchanger at the tail of the coal-fired boiler obtained in the step (4) to a DCS server through a communication module of the dust deposition monitoring PLC through a serial server for operators to perform dust blowing reference.

In the step 2, the sample data is selected to cover the main operation condition of the coal-fired thermal power generating unit, and the value m is more than or equal to 300.

Compared with the prior art, the invention has the following beneficial effects:

the invention can be used for monitoring the dust deposition pollution degree of the convection heat exchanger at the tail part of the coal-fired power station boiler and providing reference and guidance for the operation of the boiler soot blower.

The DCS server and the dust deposition monitoring PLC realize stable data communication between the serial port and the Ethernet by combining the virtual DPU program and the serial port server, and save the cost investment of directly adopting a hardware DPU.

The invention emphasizes the consideration of the deviation between the actual heat transfer capacity and the working medium heat absorption capacity of the boiler heat exchanger caused by the quick load lifting of the unit, introduces the change of the metal heat storage capacity and the working medium heat storage capacity of the heat exchanger, and improves the accuracy of the diagnosis of the dust deposition pollution of the boiler convection heat exchanger.

According to the invention, the final monitoring result corresponds to the operation of the soot blower, so that the soot blowing of the boiler convection heat exchanger can be realized according to the requirement, the boiler efficiency is improved, and the maintenance workload of the soot blower is reduced.

drawings

FIG. 1 is a schematic structural diagram of an online monitoring system for ash deposition of a convection heat exchanger at the tail of a coal-fired boiler according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

As shown in FIG. 1, the system for online monitoring of ash deposition of the convection heat exchanger at the tail of the coal-fired boiler comprises a DCS server, a serial server, an ash deposition monitoring PLC and an industrial personal computer which are connected in sequence;

the virtual DPU program running on the DCS server is in TCP/IP communication with the serial port server through a dynamic link communication interface program, and the DCS server transmits real-time process data of the running of the coal-fired thermal power generating unit to the soot monitoring PLC;

the system comprises a serial server, a DCS server, an MODBUS, a dust accumulation monitoring PLC and a communication gateway, wherein the serial server serves as a communication gateway from a serial interface to the Ethernet to realize bidirectional data transmission between the serial interface and the Ethernet interface;

The dust deposition monitoring PLC comprises a power supply module, a communication module and a processor module, wherein the communication module is connected with a serial server and is used for carrying out data communication through an MODBUS protocol, the processor module is connected with an industrial personal computer through a network cable to realize data communication, and the power supply module is used for supplying power to the dust deposition monitoring PLC;

The industrial personal computer is connected with a processor module of the dust deposition monitoring PLC and is used for debugging a dust deposition monitoring program and storing historical data;

The processor module is used for calculating the dust deposition degree of the convection heat exchanger at the tail of the coal-fired boiler in real time.

The invention relates to a real-time online monitoring method for accumulated dust of a coal-fired boiler tail convection heat exchanger online monitoring system, which comprises the following steps:

step 1: the ash deposition monitoring PLC reads real-time process data from the DCS server, wherein the real-time process data comprises load of the coal-fired thermal power generating unit, water supply flow, inlet working medium temperature of the convection heat exchanger, inlet working medium pressure of the convection heat exchanger, outlet working medium temperature of the convection heat exchanger, outlet working medium pressure of the convection heat exchanger, inlet flue gas temperature of the convection heat exchanger, outlet flue gas temperature of the convection heat exchanger, main steam flow G of the boiler, reheating steam flow D and the like;

step 2: the ash deposition monitoring PLC preprocesses the data of the coal-fired power generating unit in real time during operation, eliminates abnormal data and removes noise:

The dust deposition monitoring PLC selects m times of normal signals x for a certain real-time process data variable x read from the DCS server₁,x₂,…，x_mFor sample data, calculating an average value of the sample dataAnd standard deviation of

Reading current operation data x₀According to the discriminantJudging whether the current operation data is an abnormal value, if the judgment formula is true, taking x₀＝x_0-1+(x_0-1-x_0-2) Replacing the current value as the current normal operation data and storing; beta is an error coefficient, x_0-1、x_0-2Normal operation data stored in the previous two calculation periods;

GetPerforming next calculation as the smoothed data;

And step 3: calculating the enthalpy value i' of the working medium at the inlet of the heat exchanger and the enthalpy value i of the working medium at the outlet of the heat exchanger according to the working medium and the pressure at the inlet and the outlet of the heat exchanger;

And 4, step 4: and the processor module of the dust deposition monitoring PLC calculates a cleanliness characterization index CF of the convection heat exchanger at the tail of the coal-fired boiler based on the following formula.

c_metalAnd c_steamIs the average specific heat capacity, m, of the metal tube of the heat exchanger and the working medium in the heat exchanger_metalAnd m_steamis the mass of the metal tube of the heat exchanger and the working medium in the heat exchanger, T_metalis the average temperature of the metal tube wall of the heat exchanger, P_steamis the pressure of the working medium in the heat exchanger,t is time, s; delta t is the heat transfer temperature and pressure of the heat exchanger, DEG C; d is the flow of the working medium in the heat exchanger, kg/s; i' is the enthalpy value of the working medium at the inlet of the heat exchanger, which is checked according to the temperature and the pressure of the working medium inlet, and kJ/kg; i' is the enthalpy value of the working medium at the outlet of the heat exchanger, which is checked according to the temperature and the pressure of the working medium outlet, kJ/kg; f is the area of the heat exchanger, m²；K_idealis the ideal heat transfer coefficient of the heat exchanger, W/(m)²·℃)；

The quick load lifting of the unit causes deviation between the actual heat transfer capacity and the working medium heat absorption capacity of the convection heat exchanger at the tail of the coal-fired boiler, the first two items of the formula denominator consider the change of the heat storage of the heat exchanger caused by the metal temperature change of the heat exchanger and the change of the heat storage of the working medium caused by the steam pressure change, and a and b are corresponding correction coefficients respectively;

And 5: and (4) sending the result of the cleanliness characterization index calculation of the convection heat exchanger at the tail of the coal-fired boiler obtained in the step (4) to a DCS server through a communication module of the dust deposition monitoring PLC through a serial server for operators to perform dust blowing reference.

as a preferred embodiment of the invention, in the step 2, the selection of m needs to consider that the sample data covers the main operation condition of the coal-fired thermal power generating unit, and the value m is more than or equal to 300.

it will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.