Power plant boiler sootblower operation optimization and condition monitoring system and method

Abstract

This invention provides a system and method for optimizing the operation and monitoring the status of a sootblower in a coal-fired power plant boiler. The system includes a thermal measurement system, a physical isolation device, a server, a data conversion device or controller, and an operator station. The server is equipped with a data communication module, a database, and a sootblower operation optimization and monitoring system module. The thermal measurement system is connected to a DCS or SIS system via its data bus, or directly to the server. The DCS or SIS system is connected to the server via the physical isolation device. Through a communication protocol and communication module, thermal measurement data and data from the DCS or SIS system are transmitted to the database. The sootblower operation optimization and monitoring system module reads data from the database and stores the optimization calculation results. The operator station interacts with the database on the server for client-side monitoring. The data conversion device or controller communicates with both the server and the DCS system to implement sootblower operation optimization commands for controlling the sootblower and monitoring its operating status.

Description

Technical Field

[0001] This invention relates to the field of energy-saving retrofitting and information control of coal-fired boilers, specifically a system and method for optimizing the operation and monitoring the status of soot blowers in coal-fired power plant boilers. Background Technology

[0002] Ash and slag buildup is a common problem in coal-fired power plant boilers during operation. This buildup not only affects heat exchange and operating efficiency but also leads to high-temperature and low-temperature corrosion, increasing the risk of tube rupture on heating surfaces, reducing boiler lifespan, and compromising safe operation. Currently, pulverized coal power plant boilers are equipped with numerous soot blowers, and soot blowing is performed periodically based on operational experience or on a shift basis. However, this can easily result in over- or under-blowing of the heating surfaces. In recent years, with the development of information technology, pollution monitoring and intelligent soot blowing have been applied to pulverized coal power plant boilers. Based on the ash and dirt levels on different heating surfaces, targeted soot blowing is implemented: heavily soiled surfaces receive more frequent soot blowing, while lightly soiled surfaces receive less frequent or no soot blowing. In current power plant boiler sootblower operation optimization technologies, the optimization technologies for sootblowers located at the boiler furnace outlet or top (radiative heating surface, convective / semi-convective heating surface, and convective heating surface in the tail flue) are relatively mature. However, the optimization technology for sootblowers located in the furnace water-cooled wall area still has unscientific problems. Existing pollution monitoring and sootblower operation optimization technologies for large-capacity furnace water-cooled walls are based on Soviet empirical calculation formulas and methods for furnaces with an evaporation capacity of less than 400 t / h. For current large-capacity boilers with an evaporation capacity of 1000 t / h or more, errors introduced by the "dual ash body" model in the furnace, inadequate consideration of the non-uniformity of the furnace temperature field, and the influence of furnace geometry lead to inaccurate and unscientific calculations in existing publicly available sootblower operation optimization technologies for the furnace area. Furthermore, the corresponding sootblower operation status monitoring technology also needs continuous improvement. This invention addresses the above problems and situations by proposing a power plant boiler sootblower operation optimization and status monitoring system and method. Summary of the Invention

[0003] Technical Problem: This invention addresses the problems of inaccurate and unscientific calculations in existing technologies for monitoring pollution in the water-cooled walls of large-capacity coal-fired power plant boilers and optimizing the operation of sootblowers, as well as the need for improvement in sootblower operation status monitoring technology. It provides a solution that can better solve the problems of monitoring pollution in the water-cooled walls of large-capacity coal-fired power plant boilers and optimizing and monitoring the operation and status of sootblowers.

[0004] The technical solution of this invention to solve the technical problem is as follows:

[0005] This invention provides a system and method for optimizing and monitoring the operation of a sootblower in a coal-fired power plant boiler. The system includes a thermal measurement system, a physical isolation device, a server, a data conversion device or controller, and an operator station. The server is equipped with a data communication module, a database, and a sootblower operation optimization and monitoring system module. The sootblower operation optimization and monitoring system module includes a boiler heating surface contamination monitoring and sootblower operation optimization module and a sootblower operation status monitoring module. The thermal measurement system is connected to a DCS or SIS system via its data bus, or directly to the server. The DCS or SIS system is connected to the server via the physical isolation device. Through a communication protocol and communication module, thermal measurement point data and DCS or SIS system data are transmitted to the database. The sootblower operation optimization and monitoring system module reads data from the database and stores the optimization calculation results. The operator station interacts with the database on the server for client-side monitoring. The data conversion device or controller communicates with both the server and the DCS system to implement sootblower operation optimization commands for controlling the sootblower and monitoring its operation status.

[0006] A system and method for optimizing the operation and monitoring the condition of soot blowers in coal-fired power plant boilers were developed. The established thermal measurement system includes flue gas temperature measuring devices, steam and water temperature measuring devices, steam temperature measuring devices, flue gas pressure measuring and transmitting devices, steam pressure measuring and transmitting devices, acoustic wave measuring and sensing devices, data acquisition devices, communication cables, and a data bus. The flue gas temperature measuring devices and flue gas pressure measuring and transmitting devices are fixed to the boiler membrane wall or water-cooled wall, respectively, and arranged at the inlet and outlet of each heating surface, economizer, and air preheater, as well as the furnace outlet. These devices measure the flue gas temperature and pressure parameters at the inlet and outlet of each heating surface and the furnace outlet. The flue gas temperature measuring devices can employ thermocouples, far-infrared thermometers, or acoustic wave thermometers, and are evenly distributed in a multi-point or grid-like arrangement. The steam and water temperature... Measuring devices are respectively arranged on the inlet and outlet steam-water headers or collection boxes of each heating surface and economizer to measure the steam-water temperature parameters of each heating surface and economizer inlet and outlet. Three types of measuring devices, or one or two of them, including steam temperature measuring device, steam pressure measuring and transmitting device, and acoustic wave measuring and sensing device, are respectively installed on the straight pipe section after the sootblower valve to measure the steam temperature, pressure, and sound parameters in the sootblower. The flue gas temperature measuring device, steam-water temperature measuring device, steam temperature measuring device, and acoustic wave measuring and sensing device are respectively connected to the data acquisition device via compensating cables. The data acquisition device is connected to the data bus. The flue gas pressure measuring and transmitting device and the steam pressure measuring and transmitting device are connected to the data bus to realize the transmission of thermal measurement parameters.

[0007] A system and method for optimizing and monitoring the operation of sootblowers in coal-fired power plant boilers are disclosed. The system module includes a boiler heating surface contamination monitoring and sootblower operation optimization module, used to monitor the contamination status of the boiler furnace, various heating surfaces within the boiler, the economizer, and the air preheater, calculate the optimal economic frequency of sootblowing, and achieve optimized sootblower operation. Currently, the calculation methods for the convective heating surfaces located in the tail flue of the boiler, the radiative heating surfaces located above the furnace outlet, and the half-width heating surfaces located behind the flue gas flow of the radiative heating surfaces are publicly available technologies and will not be described further in this specification. This invention primarily focuses on the furnace contamination monitoring and sootblower operation optimization of large-capacity boilers, providing a feasible method and performing multi-method or combined calculations on the furnace outlet flue gas temperature upon which the model calculations depend.

[0008] The boiler heating surface contamination monitoring and sootblower operation optimization module includes the following steps:

[0009] Step 1: Calculate the average flue gas temperature at the furnace outlet.

[0010] In one embodiment, for the sectioning of the furnace outlet and the addition of flue gas temperature measuring devices, the flue gas temperature parameter θ of each section is measured. i Then, a weighted average of the flue gas circulation area is adopted, based on the formula...

[0011]

[0012] Find Alternatively, first determine the functional relationship between the flue gas temperature θ at the furnace outlet and the cross-sectional area of ​​the furnace outlet. (s) =f(S), based on the formula Solving by integration

[0013] The furnace outlet cross-sectional area can be divided into 4 to 16 zones according to its size, where N represents the number of furnace outlet zones; ΔS i For the area of ​​section i corresponding to the furnace outlet cross section, m 2 ;θ i The flue gas temperature corresponding to section i at the furnace outlet, in °C.

[0014] Where, θ (s) Let θ be the flue gas temperature at the furnace outlet cross-section (°C). (s) =f(s); ds is the cross-sectional area of ​​the infinitesimal element at the furnace outlet, m 2 ;

[0015] In one implementation, for calculations based on the heat balance between the boiler water-cooled walls and the flue gas in the furnace,

[0016] According to the formula

[0017]

[0018] Seeking Based on the formula

[0019] And based on the corresponding fuel flue gas temperature-enthalpy relationship chart, calculate

[0020] Among them, B j To calculate fuel consumption, kg / h, the calculation is publicly available technology; Q1 is the effective heat utilized per kg of fuel fed into the furnace, kJ, and Q1 calculation is publicly available technology; D slr h slr The heat at the inlet of the water-cooled wall, kJ; D fcq h″ represents the heat of steam outlet from the steam-water separator, in kJ; D fcq =D slr -D fcs D is the steam flow rate at the separator outlet, in kg / h. fcs h′ represents the heat of water separated by the steam-water separator, in kJ; D fcs The flow rate at the separator outlet, expressed in kg / h, can be measured using a flow meter installed at the separator outlet; D slr The feedwater flow rate at the furnace water-cooled wall inlet, in kg / h, can be determined by the economizer inlet water flow rate D. gs With desuperheating water flow rate D jwhsmc The enthalpy of steam at the outlet of the steam-water separator is obtained through flow balance calculation; h″ is the enthalpy of steam at the outlet of the steam-water separator, kJ / kg, which can be obtained by referring to the steam-water enthalpy-temperature table at the corresponding saturation pressure; h′ is the enthalpy of water after separation by the steam-water separator, kJ / kg, which can be obtained by referring to the steam-water enthalpy-temperature table at the corresponding saturation pressure; h slr The enthalpy of the feedwater at the inlet of the furnace water-cooled wall is kJ / kg, which is obtained from the steam-water enthalpy temperature table based on the feedwater temperature and feedwater pressure. The average flue gas enthalpy at the furnace outlet, kJ / kg; The average isobaric specific heat capacity of the flue gas at the furnace outlet, kJ / (kg·k), can be obtained from the table of isobaric specific heat capacity of flue gas; The furnace insulation coefficient is calculated based on heat loss and is a publicly available technology.

[0021] In one implementation, the heat exchange balance between steam / water and flue gas is calculated for each of the multiple heat-receiving surfaces in the flue gas duct between the economizer outlet and the furnace outlet, against the direction of flue gas flow. This allows the derivation of the furnace outlet flue gas temperature.

[0022] Average flue gas temperature at furnace outlet Based on the above methods and considering the specific conditions of the power plant's coal-fired boiler unit, any one, two, or three methods can be used to obtain the desired result. They can be mutually verified.

[0023] Step 2, calculate the average fouling coefficient ζ of the water-cooled wall. pj :

[0024] Based on the formula for calculating the outlet flue gas temperature of a large-capacity furnace

[0025]

[0026] We can obtain:

[0027] Substituting into the equation ζ=ψ / χ, we can obtain the fouling coefficient of the water-cooled wall:

[0028]

[0029] Among them, T a K represents the theoretical combustion temperature, and K is the adiabatic combustion enthalpy of the flame, determined by the effective heat input into the furnace, which can be calculated from the corresponding fuel flue gas temperature-enthalpy relationship chart; M is a constant related to the furnace structure, representing the position of the flame center; a l Furnace emissivity is a hypothetical emissivity representing the effective radiation of a flame; q F The unit heat load of the water-cooled wall heating surface, in kJ / m². 2 F1 is the furnace wall area, in meters. 2 The value is obtained from boiler structure calculations; χ is the angle coefficient of the water-cooled wall, which is 1 for large-capacity furnace membrane water-cooled walls.

[0030] Step 3: Calculate the economical soot blowing frequency and the optimal soot blowing time for the water-cooled wall.

[0031] Based on the formula:

[0032]

[0033] Among them, Q Fll The theoretical heat absorption by radiation in the furnace, kJ; Q Fsj For actual heat absorption, kJ; q Fll The theoretical heat load of the furnace radiant heating surface is given in kJ / m². 2 H l Furnace radiant heating surface area, m 2 ;

[0034] Under the condition that the coal composition is stable and the operating conditions are the same, ζ pj Average flue gas temperature at the furnace outlet The function, and It is a function of time;

[0035] During the time interval from t = τ0 to t = τ0 + Δτ, when the sootblower is not blowing soot, the actual radiative heat absorption in the furnace is:

[0036]

[0037] During the nth soot blowing operation in the time interval t = τ0 to t = τ0 + Δτ, the actual radiative heat absorption in the furnace is:

[0038]

[0039] The total cost of all n blows by the soot blowers is Q. chzc =nτ1mz(I ch -I0),

[0040] Benefits from n attempts to blow away dust:

[0041]

[0042] Q sy To find the maximum value, let Q... sy Since ′=0, the optimal number of blowing operations n can be calculated. Determine the optimal time for soot blowing in the water-cooled wall.

[0043] τ1 is the time (min) required for one operation of each sootblower, m is the steam flow rate (kg / min) consumed in the process, and z is the number of sootblowing guns in the furnace; I ch I0 is the source enthalpy of the soot blowing steam, kJ / kg; I0 is the enthalpy at the condenser inlet, kJ / kg.

[0044] Step 4, Calculation and setting of constraints:

[0045] Based on α=α″1-Δα1-Δα zf , Calculate the rate of change of the excess air coefficient in the furnace over a certain period of time; based on Calculate the boiler load change rate over a certain period of time;

[0046] The time period can be set to 3 minutes, 5 minutes, 10 minutes, or 15 minutes; α is the excess air coefficient in the furnace; α″1 is the excess air coefficient at the furnace outlet; Δα1 is the furnace air leakage coefficient; and Δα... zf ε0 represents the air leakage coefficient of the pulverizing system; N represents the boiler operating load (MW); ΔN represents the change in boiler operating load (MW); ε0 and μ0 are determined through big data optimization or experimentation for different coal qualities and are used as limiting conditions. These conditions are then input into the sootblower operation optimization and monitoring system module to ensure accurate judgment of the water-cooled wall contamination status under relatively stable boiler load and excess air coefficient, thereby achieving sootblower operation optimization.

[0047] A system and method for optimizing and monitoring the operation and condition of sootblowers in coal-fired power plant boilers, comprising a sootblower operation condition monitoring module:

[0048] Implementation method one involves using acoustic wave measurement and sensing devices to measure the sound intensity level of the steam flowing through the steam valve of the sootblower, thereby monitoring the operating status of the sootblower.

[0049] The soot blower's operating status signal is "running," and when t≤t0 and L≥L1, it is determined to be normal soot blowing.

[0050] The soot blower operating status signal is negative, and when t ≥ t 0，同时 When L≤L0, it is determined that the sootblower is not blowing soot; when the sootblower operating status signal is negative, and when t≥t0, and L0≤L≤L1, it is determined that the sootblower steam valve is leaking.

[0051] If the sootblower's operating status signal is "running" and t≥t0, and L≥L1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running" and t≥t0, and L≤L0, the sootblower is determined to be blocked.

[0052] Where L is the steam sound intensity level after the steam valve of the sootblower, in dB, which is measured by sound wave measurement and sensing devices; L1 is the lower limit sound intensity level during steam sootblowing, in dB, which is obtained through optimization of historical data or experiments; L0 is the upper limit sound intensity level when there is no steam flow after the steam valve of the sootblower is closed, in dB, which is obtained through optimization of historical data or experiments.

[0053] Implementation method two involves using a steam pressure measuring and transmitting device to measure the steam pressure flowing through the steam valve of the sootblower, thereby monitoring the operating status of the sootblower.

[0054] The soot blower's operating status signal is "running," and when t≤t0 and p≥p1, it is determined to be normal soot blowing.

[0055] If the sootblower operating status signal is negative, and t≥t0 and p≤p0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 and p0≤p≤p1, it is determined that the sootblower steam valve is leaking.

[0056] If the sootblower's operating status signal is "running", and t≥t0 and p≥p1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running", and t≥t0 and p≤p0, the sootblower is determined to be blocked.

[0057] Where p is the steam pressure after passing through the steam valve of the sootblower, in MPa. a The pressure is measured by a steam pressure measuring and transmitting device; p1 is the lower limit pressure during steam soot blowing, in MPa. a The pressure is obtained through optimization based on historical data or through experimentation; p0 is the upper limit pressure value when there is no steam flow after the sootblower steam valve is closed, in MPa. a Obtained through optimization or experimentation using historical data;

[0058] Implementation method three involves using a steam temperature measuring device to measure the steam temperature after it flows through the steam valve of the sootblower, thereby monitoring the operating status of the sootblower.

[0059] The soot blower's operating status signal is "running," and when t≤t0 and T≥T1, it is determined to be normal soot blowing.

[0060] If the sootblower operating status signal is negative, and t≥t0 while T≤T0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 while T0≤T≤T1, it is determined that the sootblower steam valve is leaking.

[0061] If the sootblower's operating status signal is "running", and when t≥t0 and T≥T1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running", and when t≥t0 and T≤T0, the sootblower is determined to be blocked.

[0062] Where T is the steam temperature after passing through the steam valve of the sootblower, in K, and is obtained by measuring the steam temperature; T1 is the lower limit steam temperature value during steam sootblowing, in K, and is obtained through optimization of historical data or experimentation; T0 is the upper limit temperature value when there is no steam flow after the steam valve of the sootblower is closed, in K, and is obtained through optimization of historical data or experimentation.

[0063] Wherein, t0 is the upper limit of the time required for one action of each sootblower, in minutes (min), and is determined based on the operating speed of the sootblower during the long blowing, short blowing, and semi-long blowing periods and the stroke of the sootblower.

[0064] The positive and beneficial effects of this invention are as follows: by implementing the system and method for optimizing the operation and monitoring the status of soot blowers in coal-fired power plant boilers, the problems existing in the monitoring of furnace pollution and intelligent soot blowing in existing large-capacity coal-fired power plant boilers are overcome, the level of existing intelligent soot blowing technology and the level of soot blower operation status monitoring are improved, and the operation optimization and status monitoring of soot blowers in coal-fired power plant boilers are realized, which is conducive to realizing the scientific and safe operation of soot blowers in power plant boilers. Attached Figure Description

[0065] Figure 1 This is a system schematic diagram of the present invention.

[0066] Figure 2 This is a schematic diagram illustrating the principle of calculating the flue gas temperature at the furnace outlet in one embodiment of the present invention.

[0067] Figure 3 This is a diagram showing the arrangement of the thermal measurement devices in the thermal measurement system of the present invention.

[0068] Figure 4 This is a diagram showing the arrangement of some thermal measurement devices in a thermal measurement system according to an embodiment of the present invention.

[0069] Figure 5 This is a diagram showing the arrangement of some thermal measurement devices in a thermal measurement system according to another embodiment of the present invention.

[0070] Figure 6 Two embodiments of the present invention Figure 4 , Figure 5 A-direction (B-direction) diagram. Detailed Implementation

[0071] The following embodiments of the present invention are provided to enhance understanding of this patent. These embodiments are merely illustrative of the invention and do not limit its scope.

[0072] The present invention will be further described with reference to the accompanying drawings of the embodiments of the present invention.

[0073] This invention provides a system and method for optimizing and monitoring the operation of a sootblower in a coal-fired power plant boiler. The system includes a thermal measurement system, a physical isolation device, a server, a data conversion device or controller, and an operator station. The server is equipped with a data communication module, a database, and a sootblower operation optimization and monitoring system module. The sootblower operation optimization and monitoring system module includes a boiler heating surface contamination monitoring and sootblower operation optimization module and a sootblower operation status monitoring module. The thermal measurement system is connected to a DCS or SIS system via its data bus, or directly to the server. The DCS or SIS system is connected to the server via the physical isolation device. Through a communication protocol and communication module, thermal measurement point data and DCS or SIS system data are transmitted to the database. The sootblower operation optimization and monitoring system module reads data from the database and stores the optimization results. The operator station interacts with the database on the server for client-side monitoring. The data conversion device or controller communicates with both the server and the DCS system to implement sootblower operation optimization commands for controlling the sootblower and monitoring its operation status.

[0074] A system and method for optimizing the operation and monitoring the condition of soot blowers in coal-fired power plant boilers were developed. The established thermal measurement system includes: flue gas temperature measuring devices 3, 6, 14, 17, 29, 40, and 42; steam and water temperature measuring devices 5, 16, 25, and 26; steam temperature measuring devices 10, 21, 30, and 35; flue gas pressure measuring and transmitting devices 2, 7, 13, 18, 28, 41, and 43; steam pressure measuring and transmitting devices 11, 22, 31, and 36; and acoustic wave measurement and sensing. Devices 12, 23, 32, and 37, data acquisition devices, communication cables, and data buses are included. The flue gas temperature measurement device and the flue gas pressure measurement and transmission device are fixed to the boiler water-cooled wall 1 and the membrane wall, respectively, and arranged at the inlet and outlet of each heating surface inside the boiler, the economizer, the air preheater, and the furnace outlet. These devices are used to measure the flue gas temperature and pressure parameters at the inlet and outlet of each heating surface inside the boiler and at the furnace outlet. The flue gas temperature measurement device can be a thermocouple, a far-infrared thermometer, or an acoustic temperature measurement device. The equipment is arranged in a multi-point or grid pattern. Steam and water temperature measuring devices 25, 26 and 5, 16 are respectively located on the inlet steam and water headers or collection boxes 27 and 24 of each heating surface and economizer, and on the outlet steam and water headers or collection boxes 4 and 15, used to measure the steam and water temperature parameters at the inlet and outlet of each heating surface and economizer. Three measuring devices—steam temperature measuring device, steam pressure measuring and transmitting device, and acoustic wave measuring and sensing device—or one or two of them, are installed on the straight pipe sections after the sootblower valves 9, 20, 33, and 38, respectively, used to measure the steam temperature, pressure, and sound parameters inside the sootblower, where 8, 9, 34, and 39 are sootblowers. The flue gas temperature measuring device, steam and water temperature measuring device, steam temperature measuring device, and acoustic wave measuring and sensing device are connected to the data acquisition device via compensating cables. The data acquisition device is connected to the data bus, and the flue gas pressure measuring and transmitting device and the steam pressure measuring and transmitting device are connected to the data bus to realize the transmission of thermal measurement parameters.

[0075] A system and method for optimizing and monitoring the operation of sootblowers in coal-fired power plant boilers are disclosed. The system module includes a boiler heating surface contamination monitoring and sootblower operation optimization module, used to monitor the contamination status of the boiler furnace, various heating surfaces within the boiler, the economizer, and the air preheater, calculate the optimal economic frequency of sootblowing, and achieve optimized sootblower operation. Currently, the calculation methods for the convective heating surfaces located in the tail flue of the boiler, the radiative heating surfaces located above the furnace outlet, and the half-width heating surfaces located behind the flue gas flow of the radiative heating surfaces are publicly available technologies and will not be described further in this specification. This invention primarily focuses on the furnace contamination monitoring and sootblower operation optimization of large-capacity boilers, providing a feasible method and performing multi-method or combined calculations on the furnace outlet flue gas temperature upon which the model calculations depend.

[0076] The boiler heating surface contamination monitoring and sootblower operation optimization module includes:

[0077] Step 1: Calculate the average flue gas temperature at the furnace outlet.

[0078] In one embodiment, a flue gas temperature measuring device is added at the furnace outlet to measure the flue gas temperature parameter θ. i Then, the weighted average of the flue gas flow area or the integral of the function relationship between the furnace outlet flue gas temperature and the outlet cross-sectional area is used to obtain the result. The smoke temperature measuring device can be a thermocouple, a far-infrared thermometer, or an acoustic temperature measuring device, and can be evenly distributed in a multi-point or grid-like manner for online measurement.

[0079] If the cross-sectional area of ​​the furnace outlet can be divided into 4 to 16 zones according to its size, N represents the number of furnace outlet zones; ΔS i For the corresponding furnace outlet cross section i Zone area, m 2 ;θ i Corresponding furnace outlet cross section i Smoke temperature of the zone, °C.

[0080] Calculate according to formula (1)

[0081]

[0082] Or calculate according to formula (2)

[0083]

[0084] Where, θ (s) Let θ be the flue gas temperature at the furnace outlet cross-section (°C). (s) =f(s); ds is the cross-sectional area of ​​the infinitesimal element at the furnace outlet, m 2 ;

[0085] In one implementation, based on the heat balance calculation of the boiler water-cooled wall and the flue gas in the furnace, and the temperature-enthalpy relationship of the fuel flue gas, the following is determined:

[0086] That is, according to formula (3), we first obtain

[0087]

[0088] Then, based on formula (4) and the corresponding fuel flue gas temperature-enthalpy relationship chart, the following can be calculated:

[0089]

[0090] Among them, Bj To calculate fuel consumption, kg / h, the calculation is publicly available technology; Q1 is the effective heat utilized per kg of fuel fed into the furnace, kJ, and Q1 calculation is publicly available technology; D slr h slr The heat at the inlet of the water-cooled wall, kJ; D fcq h″ represents the heat of steam outlet from the steam-water separator, in kJ; D fcq =D slr -D fcs D is the steam flow rate at the separator outlet, in kg / h. fcs h′ represents the heat of water separated by the steam-water separator, in kJ; D fcs The flow rate at the separator outlet, expressed in kg / h, can be measured using a flow meter installed at the separator outlet; D slr The feedwater flow rate at the furnace water-cooled wall inlet, in kg / h, can be determined by the economizer inlet water flow rate D. gs With desuperheating water flow rate D jwhsmc The enthalpy of steam at the outlet of the steam-water separator is obtained through flow balance calculation; h″ is the enthalpy of steam at the outlet of the steam-water separator, kJ / kg, which can be obtained by referring to the steam-water enthalpy-temperature table at the corresponding saturation pressure; h′ is the enthalpy of water after separation by the steam-water separator, kJ / kg, which can be obtained by referring to the steam-water enthalpy-temperature table at the corresponding saturation pressure; h slr The enthalpy of the feedwater at the inlet of the furnace water-cooled wall is kJ / kg, which is obtained from the steam-water enthalpy temperature table based on the feedwater temperature and feedwater pressure. The average flue gas enthalpy at the furnace outlet, kJ / kg; The average isobaric specific heat capacity of the flue gas at the furnace outlet, kJ / (kg·k), can be obtained from the table of isobaric specific heat capacity of flue gas; The furnace insulation coefficient is calculated based on heat loss and is a publicly available technology.

[0091] In one embodiment, multiple heating surfaces are arranged in the flue between the economizer outlet and the furnace outlet. The heat exchange calculation can be performed by working backwards from the heat balance calculation between steam / water and flue gas for each heating surface. Flue gas temperature at the furnace outlet.

[0092] Average flue gas temperature at furnace outlet Based on the above methods and considering the specific conditions of the power plant's coal-fired boiler unit, any one, two, or three methods can be used to obtain the desired result. They can be mutually verified.

[0093] Calculation step 2: Calculate the average fouling coefficient ζ of the water-cooled wall. pj :

[0094] According to the corrected calculation formula (5) for the flue gas temperature at the furnace outlet,

[0095]

[0096] We can obtain:

[0097] ζ=ψ / χ (7)

[0098] Substituting equation (6) into equation (7), we can obtain the fouling coefficient of the water-cooled wall:

[0099]

[0100] Among them, T a K represents the theoretical combustion temperature, and K is the adiabatic combustion enthalpy of the flame, determined by the effective heat input into the furnace, which can be calculated from the corresponding fuel flue gas temperature-enthalpy relationship chart; M is a constant related to the furnace structure, representing the position of the flame center; a l Furnace emissivity is a hypothetical emissivity representing the effective radiation of a flame; q F The unit heat load of the water-cooled wall heating surface, in kJ / m². 2 F1 is the furnace wall area, in meters. 2 The value is obtained from boiler structure calculations; χ is the angle coefficient of the water-cooled wall, which is 1 for large-capacity furnace membrane water-cooled walls.

[0101] Step 3: Calculate the economical soot blowing frequency and the optimal soot blowing time for the water-cooled wall.

[0102] According to the furnace theory, radiative heat absorption

[0103] Actual heat absorption

[0104] and basis

[0105] Where, q Fll The theoretical heat load of the furnace radiant heating surface is given in kJ / m². 2 H1 Furnace radiant heating surface area, m 2 ;

[0106] Under the condition that the coal composition is stable and the operating conditions are the same, ζ pj Average flue gas temperature at the furnace outlet The function, and It is a function of time;

[0107] During the time interval t = τ0 to t = τ0 + Δτ, if the sootblower does not blow soot, the actual radiative heat absorption in the furnace is:

[0108]

[0109] When n soot blowing cycles are performed during the time interval from t = τ0 to t = τ0 + Δτ

[0110] The actual radiative heat absorption of the furnace is

[0111] The total cost of all n blows by the soot blowers is Q. chzc =nτ1mz(I ch -I0)

[0112] Benefits from n attempts to blow away dust:

[0113]

[0114] Q sy To find the maximum value, let Q... sy Since ′=0, the optimal number of blowing operations n can be calculated. Determine the optimal time for soot blowing in the water-cooled wall.

[0115] τ1 is the time (min) required for one operation of each sootblower, m is the steam flow rate (kg / min) consumed in the process, and z is the number of sootblowing guns in the furnace; I ch I0 is the source enthalpy of the soot blowing steam, kJ / kg; I0 is the enthalpy at the condenser inlet, kJ / kg.

[0116] Step 4: Calculation and setting of limiting conditions:

[0117] The rate of change of the excess air coefficient in the furnace over a certain period of time is calculated based on α = α″1 - Δα1 - Δα. zf ,

[0118] Calculation of boiler load change rate over a certain period of time.

[0119] A specific time period can be set to 3 minutes, 5 minutes, 10 minutes, or 15 minutes.

[0120] Where α is the excess air coefficient in the furnace, α″1 is the excess air coefficient at the furnace outlet, Δα1 is the air leakage coefficient in the furnace, and Δα zf ε0 represents the air leakage coefficient of the pulverizing system; N represents the boiler operating load (MW); ΔN represents the change in boiler operating load (MW); ε0 and μ0 are determined through big data optimization or experimentation for different coal qualities and are used as limiting conditions. These conditions are then input into the sootblower operation optimization and monitoring system module to ensure accurate judgment of the water-cooled wall contamination status under relatively stable boiler load and excess air coefficient, thereby achieving sootblower operation optimization.

[0121] A system and method for optimizing and monitoring the operation and condition of sootblowers in coal-fired power plant boilers, comprising a sootblower operation condition monitoring module:

[0122] Implementation method one: Utilizing acoustic wave measurement and sensing devices to measure the sound intensity level of the steam flowing through the steam valve of the sootblower, thereby monitoring the operating status of the sootblower.

[0123] The soot blower's operating status signal is "running," and when t≤t0 and L≥L1, it is determined to be normal soot blowing.

[0124] If the sootblower operating status signal is negative, and t≥t0 and L≤L0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 and L0≤L≤L1, it is determined that the sootblower steam valve is leaking.

[0125] If the sootblower's operating status signal is "running" and t≥t0, and L≥L1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running" and t≥t0, and L≤L0, the sootblower is determined to be blocked.

[0126] Where L is the steam sound intensity level after the steam valve of the sootblower, in dB, which is measured by sound wave measurement and sensing devices; L1 is the lower limit sound intensity level during steam sootblowing, in dB, which is obtained through optimization of historical data or experiments; L0 is the upper limit sound intensity level when there is no steam flow after the steam valve of the sootblower is closed, in dB, which is obtained through optimization of historical data or experiments.

[0127] Implementation method two involves using a steam pressure measuring and transmitting device to measure the steam pressure flowing through the steam valve of the sootblower, thereby monitoring the operating status of the sootblower.

[0128] The soot blower's operating status signal is "running," and when t≤t0 and p≥p1, it is determined to be normal soot blowing.

[0129] If the sootblower operating status signal is negative, and t≥t0 and p≤p0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 and p0≤p≤p1, it is determined that the sootblower steam valve is leaking.

[0130] If the sootblower's operating status signal is "running", and t≥t0 and p≥p1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running", and t≥t0 and p≤p0, the sootblower is determined to be blocked.

[0131] Where p is the steam pressure after passing through the steam valve of the sootblower, in MPa. a The pressure is measured by a steam pressure measuring and transmitting device; p1 is the lower limit pressure during steam soot blowing, in MPa. a The pressure is obtained through optimization based on historical data or through experimentation; p0 is the upper limit pressure value when there is no steam flow after the sootblower steam valve is closed, in MPa. a Obtained through optimization or experimentation using historical data;

[0132] Implementation method three involves using a steam temperature measuring device to measure the steam temperature after it flows through the steam valve of the sootblower, thereby monitoring the operating status of the sootblower.

[0133] The soot blower's operating status signal is "running," and when t≤t0 and T≥T1, it is determined to be normal soot blowing.

[0134] If the sootblower operating status signal is negative, and t≥t0 while T≤T0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 while T0≤T≤T1, it is determined that the sootblower steam valve is leaking.

[0135] If the sootblower's operating status signal is "running", and when t≥t0 and T≥T1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running", and when t≥t0 and T≤T0, the sootblower is determined to be blocked.

[0136] Where T is the steam temperature after passing through the steam valve of the sootblower, in K, and is obtained by measuring the steam temperature; T1 is the lower limit temperature value during steam sootblowing, in K, and is obtained through optimization of historical data or experimentation; T0 is the upper limit temperature value when there is no steam flow after the steam valve of the sootblower is closed, in K, and is obtained through optimization of historical data or experimentation.

[0137] Wherein, t0 is the upper limit of the time required for one action of each sootblower, in minutes (min), and is determined based on the operating speed of the sootblower during the long blowing, short blowing, and semi-long blowing periods and the stroke of the sootblower.

Claims

1. This invention provides a method for optimizing and monitoring the operation of a sootblower in a coal-fired power plant boiler. The method includes a thermal measurement system, a physical isolation device, a server, a data conversion device or controller, and an operator station. The server is equipped with a data communication module, a database, and a sootblower operation optimization and monitoring system module. The sootblower operation optimization and monitoring system module includes a boiler heating surface contamination monitoring and sootblower operation optimization module and a sootblower operation status monitoring module. The thermal measurement system is connected to a DCS system or SIS system via its data bus, or directly to the server. The DCS system or SIS system is connected to the server via a physical isolation device. Through a communication protocol and communication module, thermal measurement point data and DCS system or SIS system data are transmitted to the database. The sootblower operation optimization and monitoring system module reads data from the database and stores the optimization calculation results. The operator station interacts with the database on the server for client-side monitoring. The data conversion device or controller communicates with both the server and the DCS system to implement sootblower operation optimization commands for controlling the sootblower and monitoring its operation status. The thermal measurement system includes flue gas temperature measuring devices, steam and water temperature measuring devices, steam temperature measuring devices, flue gas pressure measuring and transmitting devices, steam pressure measuring and transmitting devices, acoustic wave measuring and sensing devices, data acquisition devices, communication cables, and data buses. The flue gas temperature measuring devices and flue gas pressure measuring and transmitting devices are fixed to the boiler membrane wall or water-cooled wall, respectively, and arranged at the inlet and outlet of each heating surface inside the boiler, the economizer, the air preheater, and the furnace outlet. They are used to measure the flue gas temperature and pressure parameters at the inlet and outlet of each heating surface inside the boiler and at the furnace outlet. The flue gas temperature measuring devices can use thermocouples, far-infrared thermometers, or acoustic wave thermometers, and are evenly distributed in a multi-point or grid-like arrangement. The steam and water temperature measuring devices are arranged at each heating surface... On the inlet and outlet steam-water headers or collection boxes of the hot surface and economizer, steam and water temperature parameters of each heating surface and economizer inlet and outlet are measured; three measuring devices, or one or two of them, namely steam temperature measuring device, steam pressure measuring and transmitting device, and sound wave measuring and sensing device, are installed on the straight pipe section after the sootblower valve, respectively, to measure the steam temperature, pressure, and sound parameters in the sootblower; the flue gas temperature measuring device, steam and water temperature measuring device, steam temperature measuring device, and sound wave measuring and sensing device are connected to the data acquisition device via compensating cables, the data acquisition device is connected to the data bus, and the flue gas pressure measuring and transmitting device and the steam pressure measuring and transmitting device are connected to the data bus to realize the transmission of thermal measurement parameters; Its features are, The boiler heating surface contamination monitoring and sootblower operation optimization module includes the following steps: Step 1: Calculate the average flue gas temperature at the furnace outlet. For furnace outlet partitioning and the addition of flue gas temperature measurement devices, the flue gas temperature parameter θ for each partition should be measured. i Then, a weighted average of the flue gas circulation area is adopted, based on the formula... Find Alternatively, first determine the functional relationship between the flue gas temperature θ at the furnace outlet and the cross-sectional area of ​​the furnace outlet. (s) =f(S), based on the formula Solving by integration The furnace outlet cross-sectional area can be divided into 4 to 16 zones according to size, N 代 Number of furnace outlet zones; ΔSi 为对 The area of ​​the furnace outlet section i is given in m. 2 ;θ i The flue gas temperature corresponding to section i at the furnace outlet, in °C; Where, θ (s) Let θ be the flue gas temperature at the furnace outlet cross-section (°C). (s) =f(s); ds is the cross-sectional area of ​​the infinitesimal element at the furnace outlet, m 2 For calculations based on the heat balance between the boiler water-cooled wall and the flue gas in the furnace, the formula should be used. Seeking Based on the formula And based on the corresponding fuel flue gas temperature-enthalpy relationship chart, calculate Among them, B j Fuel consumption is calculated in kg / h; Q1 is the effective heat utilized per kg of fuel fed into the furnace, kJ; D slr h slr The heat at the inlet of the water-cooled wall, kJ; D fcq h″ represents the heat of steam outlet from the steam-water separator, in kJ; D fcq =D slr -D fcs D is the steam flow rate at the separator outlet, in kg / h. fcs h′ represents the heat of water separated by the steam-water separator, in kJ; D fcs D is the separator outlet water flow rate, kg / h; slr h″ is the inlet feedwater flow rate of the furnace water-cooled wall, kg / h; h′ is the steam enthalpy at the outlet of the steam-water separator, kJ / kg; h″ is the enthalpy of the water after separation by the steam-water separator, kJ / kg; h slr The enthalpy of the feedwater at the inlet of the furnace water-cooled wall is kJ / kg; The average flue gas enthalpy at the furnace outlet, kJ / kg; The average isobaric specific heat capacity of the flue gas at the furnace outlet is given in kJ / (kg·k). The furnace insulation coefficient; For the heat exchange calculation of steam-water and flue gas heat balance between multiple heating surfaces in the flue gas duct between the economizer outlet and the furnace outlet, against the direction of flue gas flow, the flue gas temperature at the furnace outlet can be deduced. Average flue gas temperature at furnace outlet It can be obtained by using any one, two, or three methods described above. They can be mutually verified; Step 2, calculate the average fouling coefficient ζ of the water-cooled wall. pj : According to the formula: ζ=ψ / χ The fouling coefficient ζ of the water-cooled wall can be calculated. pj Among them, T a K represents the theoretical combustion temperature, with the effective heat input into the furnace as the adiabatic combustion enthalpy of the flame; M is a constant related to the furnace structure, representing the position of the flame center; a l Furnace emissivity is a hypothetical emissivity representing the effective radiation of a flame; q F The unit heat load of the water-cooled wall heating surface, in kJ / m². 2 F1 is the furnace wall area, in meters. 2 ; χ is the angular coefficient of the water-cooled wall. For large-capacity furnace membrane water-cooled walls, χ = 1; Step 3: Calculate the economical soot blowing frequency and the optimal soot blowing time for the water-cooled wall: Based on the formula: Among them, Q Fll The theoretical heat absorption by radiation in the furnace, kJ; Q Fsj For actual heat absorption, kJ; q Fll The theoretical heat load of the furnace radiant heating surface is given in kJ / m². 2 H1 Furnace radiant heating surface area, m 2 ; Under the condition that the coal composition is stable and the operating conditions are the same, ζ pj Average flue gas temperature at the furnace outlet The function, and It is a function of time; During the time interval from t = τ0 to t = τ0 + Δτ, when the sootblower is not blowing soot, the actual radiative heat absorption in the furnace is: During the nth soot blowing operation in the time interval t = τ0 to t = τ0 + Δτ, the actual radiative heat absorption in the furnace is: The total cost of all n blows by the soot blowers is Q. chzc =nτ1mz(I ch -I0), Benefits from n attempts to blow away dust: Q sy To find the maximum value, let Q... sy Since ′=0, the optimal number of blowing operations n can be calculated. Determine the optimal soot blowing time for the water-cooled wall; τ1 is the time (min) required for one operation of each sootblower, m is the steam flow rate (kg / min) consumed in the process, and z is the number of sootblowing guns in the furnace; I ch I0 is the source enthalpy of the soot blowing steam, kJ / kg; I0 is the enthalpy at the condenser inlet, kJ / kg. Step 4, Calculation and setting of constraints: Based on α=α″1-Δα1-Δα zf , Calculate the rate of change of the excess air coefficient in the furnace over a certain period of time; based on Calculate the boiler load change rate over a certain period of time; The time period can be set to 3 minutes, 5 minutes, 10 minutes, or 15 minutes; α is the excess air coefficient in the furnace; α″1 is the excess air coefficient at the furnace outlet; Δα1 is the furnace air leakage coefficient; and Δα... zf ε0 represents the air leakage coefficient of the pulverizing system; N represents the boiler operating load (MW); ΔN represents the change in boiler operating load (MW); ε0 and μ0 are determined through big data optimization or experimentation for different coal qualities and are used as limiting conditions, which are then input into the sootblower operation optimization and monitoring system module. The feature is that the sootblower operation status monitoring module includes: The operating status of the sootblower is monitored by measuring the sound intensity level of the steam flowing through the steam valve of the sootblower using sound wave measurement and sensing devices. The soot blower's operating status signal is "running," and when t≤t0 and L≥L1, it is determined to be normal soot blowing. If the sootblower operating status signal is negative, and t≥t0 and L≤L0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 and L0≤L≤L1, it is determined that the sootblower steam valve is leaking. If the sootblower's operating status signal is "running" and t≥t0, and L≥L1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running" and t≥t0, and L≤L0, the sootblower is determined to be blocked. Where L is the steam sound intensity level after the steam valve of the sootblower, in dB; L1 is the lower limit sound intensity level during steam sootblowing, in dB; and L0 is the upper limit sound intensity level when there is no steam flow after the steam valve of the sootblower is closed, in dB. The steam pressure after flowing through the steam valve of the sootblower is measured using a steam pressure measuring and transmitting device to monitor the operating status of the sootblower. The soot blower's operating status signal is "running," and when t≤t0 and p≥p1, it is determined to be normal soot blowing. If the sootblower operating status signal is negative, and t≥t0 and p≤p0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 and p0≤p≤p1, it is determined that the sootblower steam valve is leaking. If the sootblower's operating status signal is "running", and t≥t0 and p≥p1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running", and t≥t0 and p≤p0, the sootblower is determined to be blocked. Where p is the steam pressure after passing through the steam valve of the sootblower, in MPa. a p1 is the minimum pressure during steam soot blowing, in MPa. a p0 is the upper limit pressure value when there is no steam flow after the sootblower steam valve is closed, in MPa. a ; The operating status of the sootblower is monitored by measuring the steam temperature after it flows through the steam valve of the sootblower using a steam temperature measuring device. The soot blower's operating status signal is "running," and when t≤t0 and T≥T1, it is determined to be normal soot blowing. If the sootblower operating status signal is negative, and t≥t0 while T≤T0, it is determined that the sootblower is not blowing soot; if the sootblower operating status signal is negative, and t≥t0 while T0≤T≤T1, it is determined that the sootblower steam valve is leaking. If the sootblower's operating status signal is "running", and when t≥t0 and T≥T1, the sootblower is determined to be stuck; if the sootblower's operating status signal is "running", and when t≥t0 and T≤T0, the sootblower is determined to be blocked. Where T is the steam temperature after passing through the steam valve of the sootblower, in K; T1 is the lower limit temperature value during steam sootblowing, in K; and T0 is the upper limit temperature value when there is no steam flow after the steam valve of the sootblower is closed, in K. The above-mentioned t0 is the upper limit of the time required for one operation of each sootblower, in minutes (min), which is determined according to the operating speed of the sootblower during the long blowing, short blowing, and semi-long blowing periods and the stroke of the sootblower.

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