CN-121977197-A - Full-load air leakage on-line monitoring system and method based on air preheater and tail flue

Abstract

The invention discloses a full-load air leakage on-line monitoring system and method for a boiler air preheater and a tail flue thereof, and belongs to the technical field of thermal energy engineering. The system comprises a full-section automatic back-blowing stable inspection system, a data preprocessing module, a full-load air leakage rate calculation module, a sealing characteristic analysis module and a closed-loop maintenance and optimization module. The method comprises the steps of continuously collecting key section oxygen parameters in a full load interval of a boiler through a patrol system, inputting an air leakage rate model covering the full load to calculate real-time air leakage rate after temperature dust compensation pretreatment, generating an air leakage rate-load characteristic curve based on multi-load air leakage rate data, analyzing load adaptation characteristics of a sealing system, and realizing air leakage early warning, overhaul guidance and closed-loop operation of operation correction of a draught fan according to real-time air leakage rate and characteristic analysis results. The invention solves the problems of low operation energy efficiency and high energy consumption caused by insufficient dynamic capture capability of air leakage and loss of full load monitoring.

Inventors

• GUO KAI
• WANG DONG
• ZHOU JING
• JIN LIMEI
• YANG ZUWANG
• ZHANG JIAN
• LI YANSEN
• LIU KAI
• LIU QI
• WANG QINGXUAN
• LI MENG
• ZHANG SHUN
• WANG YALIN
• FU DONGJIE
• ZHANG JINGSHUAI

Assignees

• 华电淄博热电有限公司
• 华电国际电力股份有限公司技术服务分公司
• 西安格瑞电力科技有限公司

Dates

Publication Date

20260505

Application Date

20260204

Claims (10)

1. 1. The full-load air leakage on-line monitoring method based on the air preheater and the tail flue is characterized by comprising the following steps of: in a full-load operation interval of the boiler, continuously and real-time full-section patrol acquisition is carried out on oxygen parameters of an air conditioner inlet and outlet, an electric precipitator outlet and a tail flue by utilizing an oxygen sensor; Preprocessing the collected oxygen amount data to eliminate environmental interference; the pretreatment comprises temperature compensation, dust interference correction, real-time dust concentration acquisition, attenuation correction and dust shielding influence elimination, wherein the temperature compensation is used for acquiring the ambient temperature of an oxygen sensor in a boiler, compensating and correcting an original oxygen measurement value according to the corresponding relation between the ambient temperature and theoretical use temperature deviation of the oxygen sensor; The method comprises the steps of inputting preprocessed oxygen amount data, equipment structure parameters and real-time operation condition data into an air leakage rate calculation model together, and carrying out online calculation to obtain the real-time air leakage rate, wherein the air leakage rate calculation model is a model covering 0-100% of rated load, and comprehensively correcting by introducing an oxygen amount correction coefficient and a condition correction function according to the ratio of an oxygen amount difference value of an inlet and an outlet to a theoretical maximum oxygen amount difference value, and the condition correction function is constructed based on real-time flue gas pressure, flue gas temperature and a sealing gap actual measurement value; integrating real-time air leakage rate data under different loads, generating an air leakage rate-load characteristic curve, analyzing the adaptation characteristic and the change rule of the air preheater sealing system in a full load interval, and outputting a sealing characteristic analysis result; and based on the real-time air leakage rate and the sealing characteristic analysis result, executing the maintenance and optimization operation of a closed loop.
2. 2. The method for on-line monitoring of full-load air leakage based on an air preheater and a tail flue according to claim 1, wherein the step of constructing the air leakage rate calculation model comprises the steps of establishing a calculation equation containing a working condition correction function determined by real-time flue gas pressure, flue gas temperature and a sealing gap actual measurement value based on an oxygen balance principle, wherein the equation is as follows: ; Wherein, the In order to achieve the air leakage rate, For the amount of oxygen at the inlet of the plant, For the amount of oxygen at the outlet of the apparatus, As the amount of oxygen in the ambient air, For the correction coefficient of the oxygen amount, And correcting the function for the working condition.
3. 3. The full-load air leakage on-line monitoring method based on the air preheater and the tail flue according to claim 1 is characterized in that the step of analyzing the adaptation characteristic of the sealing system comprises the steps of calculating the air leakage rate change rates of different load sections according to the air leakage rate-load characteristic curve, identifying a load sensitive section, and combining sealing piece state data to locate weak links with serious abrasion or deformation.
4. 4. The method for on-line monitoring of full-load air leakage based on an air preheater and a tail flue according to claim 1, wherein the closed-loop maintenance and optimization operation comprises at least one of air leakage early warning, maintenance opinion generation or induced draft fan operation correction, and the early warning step comprises the steps of calling a corresponding air leakage rate threshold according to the current boiler load, comparing the real-time air leakage rate with the threshold and generating grading early warning information.
5. 5. An air preheater and tail flue based full-load air leakage online monitoring system, which is characterized by being used for implementing the method of any one of claims 1-4, and comprising the following steps: The full-section automatic back-blowing stable inspection system is used for continuously inspecting oxygen quantity parameters in real time on key sections of an inlet and an outlet of the air preheater, an outlet of the electric dust collector and a tail flue in a full-load operation interval of the boiler; the data preprocessing module is used for performing temperature compensation and dust interference correction on the oxygen quantity parameters acquired by the inspection system so as to eliminate measurement deviation caused by a high-temperature high-dust environment and obtain preprocessed oxygen quantity data which can be used for calculation; The full-load air leakage rate calculation module is internally provided with an air leakage rate calculation model covering 0-100% of rated load and is used for calculating and outputting the real-time air leakage rate of the equipment under the current load on line according to the preprocessed oxygen amount data, the equipment structure parameters and the real-time operation condition data; The sealing characteristic analysis module is used for generating a characteristic curve of the air leakage rate changing along with the load based on the real-time air leakage rate data under different loads output by the full-load air leakage rate calculation module, and analyzing the adaptation characteristic and the change rule of the air preheater sealing system in the full-load interval so as to output a sealing characteristic analysis result; and the closed-loop maintenance and optimization module is used for executing closed-loop maintenance and optimization operation based on the real-time air leakage rate and the sealing characteristic analysis result.
6. 6. The full-load air leakage on-line monitoring system based on the air preheater and the tail flue is characterized in that the full-section automatic back-blowing stable inspection system comprises a track, a movable oxygen sensor moving along the track and an automatic back-blowing module for removing dust deposit of a sensor probe, wherein the track is arranged on the section of an inlet and an outlet of the air preheater or an outlet flue of an electric dust collector, triggering of the automatic back-blowing module is based on dust concentration monitored in real time by a dust concentration sensor or a preset pressure difference threshold, and a back-blowing air source pipeline and a control valve of the automatic back-blowing module are arranged outside the flue, and a back-blowing nozzle of the back-blowing module penetrates through the wall of the flue and corresponds to the position of the probe of the oxygen sensor.
7. 7. The full-load air leakage on-line monitoring system based on the air preheater and the tail flue according to claim 5, wherein in the data preprocessing module, the temperature compensation is modified by a function based on the ambient temperature of a sensor, and the dust interference modification is modified by a function based on the concentration of dust in real time.
8. 8. The on-line monitoring system for full-load air leakage based on an air preheater and a tail flue according to claim 5, wherein the construction basis of the air leakage rate calculation model comprises: The equipment structure parameters are the design value of the sealing gap of the air preheater, the sectional area of the flue and the resistance coefficient of the air flow channel; Real-time operation condition data including boiler load, flue gas temperature, flue gas pressure and air flow; the air leakage rate calculation model is constructed based on the oxygen balance principle.
9. 9. The on-line monitoring system for full-load air leakage based on an air preheater and a tail flue according to claim 5, wherein the analysis logic of the seal characteristic analysis module comprises: Based on the air leakage rate-load characteristic curve, identifying a load sensitive interval in which the air leakage rate change rate exceeds a preset threshold value; And analyzing the state change of the sealing element in the load sensitive interval by combining the real-time monitoring data of the sealing gap, analyzing the relevance of the abrasion, deformation and load change of the sealing element, positioning the weak link of the sealing system and storing the analysis result.
10. 10. The full-load air leakage on-line monitoring system based on the air preheater and the tail flue according to claim 5, wherein the operation executed by the closed-loop maintenance and optimization module comprises the steps of generating an air leakage early warning signal, outputting seal overhaul guide information and generating a dynamic correction basis of operation parameters of a draught fan, and the early warning logic of the closed-loop maintenance and optimization module comprises the steps of presetting a multi-stage air leakage rate threshold value which is dynamically mapped with a load, and generating an early warning signal containing the position and degree of air leakage when the real-time air leakage rate exceeds the threshold value corresponding to the current load.

Description

Full-load air leakage on-line monitoring system and method based on air preheater and tail flue Technical Field The invention relates to the technical field of thermal energy engineering, in particular to a full-load air leakage on-line monitoring system and method based on an air preheater and a tail flue. Background The air preheater is a core auxiliary machine of a large-scale power station boiler, and is used for heating air by recycling flue gas waste heat so as to improve combustion efficiency, and the operation state of the air preheater directly influences the heat efficiency, energy consumption and operation safety of a boiler system. However, in the long-term operation of the air preheater, the problems of air leakage and blockage caused by abrasion and deformation of a sealing element and condensation and adhesion of ammonium bisulfate in flue gas, such as reduction of hot air temperature, increase of energy consumption of a feeding and guiding air machine, increase of coal consumption for power generation and the like are easily caused, and particularly under the background of increasingly strict environmental protection requirements, the air leakage and blockage risk of the air preheater are further aggravated by the component change of flue gas after denitration and transformation. Most of the existing air preheater air leakage rate monitoring methods adopt a fixed point sampling mode in a high-temperature high-dust environment, full-section coverage cannot be realized, accurate data cannot be obtained continuously, air leakage change cannot be captured in real time, meanwhile, a monitoring model based on limited working conditions cannot construct continuous analysis capability for covering a 0-100% load interval, and the rule of air leakage characteristics along with load change is difficult to be revealed completely. The limitation of hysteresis distortion and model coverage of data acquisition commonly leads to that the existing system is difficult to provide a reliable real-time air leakage state, and is difficult to support equipment early warning, maintenance and operation optimization oriented to all working conditions, so that the operation economy of a unit is seriously influenced, the energy consumption is high, and even potential safety hazards exist. Disclosure of Invention The invention aims to provide an on-line monitoring system and method for full-load air leakage based on an air preheater and a tail flue, so as to solve the problems. The technical scheme of the invention is as follows: An on-line monitoring method for full-load air leakage based on an air preheater and a tail flue comprises the following steps: in a full-load operation interval of the boiler, continuously and real-time full-section patrol acquisition is carried out on oxygen parameters of an air conditioner inlet and outlet, an electric precipitator outlet and a tail flue by utilizing an oxygen sensor; preprocessing the collected oxygen amount data to eliminate environmental interference; The pretreatment comprises temperature compensation, dust interference correction, real-time dust concentration acquisition, attenuation correction and dust shielding influence elimination, wherein the temperature compensation is used for acquiring the ambient temperature of an oxygen sensor in a boiler, compensating and correcting an original oxygen measurement value according to the corresponding relation between the ambient temperature and theoretical use temperature deviation of the oxygen sensor; The method comprises the steps of inputting preprocessed oxygen amount data, equipment structure parameters and real-time operation condition data into an air leakage rate calculation model together, and carrying out online calculation to obtain the real-time air leakage rate, wherein the air leakage rate calculation model is a model covering 0-100% of rated load, and comprehensively correcting by introducing an oxygen amount correction coefficient and a condition correction function according to the ratio of an oxygen amount difference value of an inlet and an outlet to a theoretical maximum oxygen amount difference value, and the condition correction function is constructed based on real-time flue gas pressure, flue gas temperature and a sealing gap actual measurement value; integrating real-time air leakage rate data under different loads, generating an air leakage rate-load characteristic curve, analyzing the adaptation characteristic and the change rule of the air preheater sealing system in a full load interval, and outputting a sealing characteristic analysis result; and based on the real-time air leakage rate and the sealing characteristic analysis result, executing the maintenance and optimization operation of a closed loop. Further, the construction step of the air leakage rate calculation model comprises the steps of establishing a calculation equation containing a working condition correction function determined by