本文選題：負荷變動　切入點：NO_x波動　出處：《浙江大學》2017年碩士論文　論文類型：學位論文

【摘要】：鍋爐風煤匹配特性對鍋爐的經濟、環(huán)保燃燒有著重大的影響。隨著發(fā)電行業(yè)政策逐漸向新能源發(fā)電的傾斜,在AGC的控制下,火電廠需要頻繁的調整負荷,而在AGC指令下負荷變動時,由于燃燒控制系統(tǒng)參數響應的滯后性,入爐的風煤比往往偏離最佳風煤比,導致爐內燃燒不良,表現為燃燒氧量、NO_x大幅波動。針對電廠330MW燃煤機組在變負荷過程中出現的NO_x波動問題,主要從風煤匹配的角度切入,考慮實際入爐風煤相對于調節(jié)機構存在一定的滯后性,對機組運行過程中風煤量的控制過程進行優(yōu)化,以改善變負荷過程中入爐風煤的匹配性,達到降低燃燒NO_x的目的,實現清潔、高效的負荷調節(jié)。首先,對大量機組日常運行的DCS數據進行統(tǒng)計,選取出20個具有代表性的變負荷工況,對變負荷過程中機組各參數進行分析,提出風煤匹配在機組變負荷運行過程中具有重要的意義,直接導致負荷變動時NO_x出現大幅度波動。接著,進行變負荷過程中的磨煤機試驗,對調節(jié)過程中的風煤量數據進行在線監(jiān)測,分析數據研究入爐風煤量的滯后特性。考慮到分析過程對大量試驗數據的嚴重依賴性,在線監(jiān)測數據的準確度直接影響分析結果,故對風量與煤粉濃度的測量設備和在線監(jiān)測系統(tǒng)進行設計優(yōu)化,為試驗數據的測量奠定基礎。對試驗結果的分析顯示入爐風量對控制系統(tǒng)的響應速度較快,而入爐煤量則相對于給煤機存在較長滯后時間,升負荷時大概為7 min,降負荷時大概為9 min。然后根據入爐風煤的時間模型,結合機組實際參數及AGC條件下復雜的工況特性,對試驗結果進行數學分析,得出入爐風煤的平均變化速率,制定鍋爐運行的調整策略:升負荷時二次風量滯后1 min開始調節(jié),以7.5t/min的速率增加至目標風量;降負荷時二次風進行超前1 min開始,以9t/min的速率線性減少至目標風量。并對比機組良好運行的工況數據,驗證了調整方案的可行性。最后,利用試驗數據對鍋爐總風煤匹配特性和制粉系統(tǒng)匹配特性進行分析,研究煤量調節(jié)幅度、調節(jié)基準、風機壓力以及風門特性對風煤匹配特性的影響,為鍋爐燃燒系統(tǒng)的優(yōu)化提供依據。
[Abstract]:The matching characteristics of boiler air and coal have a great influence on boiler economy and environmental protection combustion. With the policy of power generation gradually tilting towards new energy generation, under the control of AGC, the power plant needs to adjust the load frequently. However, when the load changes under the AGC instruction, because of the lag of the parameter response of the combustion control system, the air-coal ratio in the furnace often deviates from the optimum air-coal ratio, which leads to the bad combustion in the furnace. In view of the NO_x fluctuation of 330MW coal-fired units in power plant during the process of changing load, mainly from the angle of air-coal matching, considering the lag of actual blast coal with respect to the regulating mechanism, it is shown that the combustion oxygen quantity is greatly fluctuating. The control process of apoplectic coal is optimized in order to improve the matching of blast coal in the process of variable load, to reduce the NO_x of combustion, and to realize clean and efficient load regulation. The DCS data of daily operation of a large number of units are statistically analyzed, 20 representative variable load conditions are selected, and the parameters of the units are analyzed in the process of variable load. It is pointed out that the matching of air and coal is of great significance in the process of variable load operation of the units. The NO_x fluctuates greatly when the load changes directly. Then, the coal mill test in the process of changing load is carried out, and the data of air and coal quantity in the process of adjustment are monitored on line. Considering the heavy dependence of the analysis process on a large number of test data, the accuracy of on-line monitoring data directly affects the analysis results. Therefore, the design and optimization of the measuring equipment and on-line monitoring system for air volume and pulverized coal concentration are carried out, which lays a foundation for the measurement of test data. The analysis of test results shows that the response speed of air volume into furnace to the control system is relatively fast. Compared with the coal feeder, the coal quantity in the furnace has a long lag time, which is about 7 mins when the load is raised and 9 mins when the load is reduced. Then, according to the time model of the blast coal into the furnace, combined with the actual parameters of the unit and the complex operating conditions under the AGC condition, Through mathematical analysis of the test results, the average rate of change of the blast coal into the furnace is obtained, and the adjustment strategy of boiler operation is made: the secondary air volume is adjusted by 1 min lag at the time of increasing load, and the rate of 7.5 t / min increases to the target air volume; When the load is lowered, the secondary air starts 1 min ahead, and the speed of 9 t / min is reduced linearly to the target air volume. The feasibility of the adjustment scheme is verified by comparing the operating condition data of the unit with good operation. Based on the test data, the matching characteristics of the total air coal and the pulverized coal production system are analyzed, and the influence of the coal quantity adjustment amplitude, the regulating datum, the fan pressure and the air valve characteristics on the air coal matching characteristics are studied. It provides the basis for the optimization of boiler combustion system.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM621

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