本文選題：切圓燃煤鍋爐　切入點：NO_x排放　出處：《華北電力大學》2015年碩士論文

【摘要】：煤炭是我國最主要的一次能源,然而煤的燃燒對環(huán)境造成了極大的破壞,燃燒過程中產(chǎn)生的粉塵、硫氧化物和氮氧化物是我國大氣污染主要來源。電站鍋爐燃煤占我國總煤炭消耗的一半以上,為此,電站鍋爐清潔高效燃燒就成為我國節(jié)能減排工作的重中之重。我國在“十五”期間基本解決了電站鍋爐煤粉低負荷穩(wěn)定燃燒問題;“十一五”期間集中解決煙氣脫硫、點火啟動節(jié)油問題;“十二五”期間將重點解決氮氧化物排放問題。目前已經(jīng)有很多種電站鍋爐降低NO_x排放的技術(shù),包括低NO_x燃燒技術(shù)和催化還原脫硝技術(shù)等。從綜合改造費用、脫硝效率和后期運行維護費用對比可以看出低NO_x燃燒技術(shù)在控制NO_x方面的優(yōu)勢,是電廠鍋爐脫硝應該初步采用的措施。本文就是在這樣的背景下,以某電廠300MW四角切圓貧煤鍋爐為研究對象,運用Fluent數(shù)值計算軟件對低氮燃燒改造前后爐內(nèi)的流動、傳熱和燃燒進行預測,以期對電廠實際改造及改造后運行提供指導。首先,簡單介紹了國內(nèi)外低氮燃燒技術(shù)的發(fā)展,分析比較得出針對本臺鍋爐改造可能的方案。其次,介紹數(shù)值計算方法在本文改造應用中所用到的數(shù)學模型。然后,運用Fluent軟件對鍋爐改造前和和改造后100%負荷、80%負荷和60%負荷工況進行數(shù)值模擬計算,研究爐內(nèi)流場、溫度場和組分場的分布變化,驗證改造方案的可行性,并通過初步驗收試驗結(jié)果與計算結(jié)果對比分析。研究結(jié)果表明:數(shù)值計算結(jié)果與初步性能試驗結(jié)果基本吻合。低NO_x燃燒改造后,鍋爐燃燒效率偏低、飛灰含碳量偏高及NO_x排放濃度高均得到極大改善。同時,改造后容易產(chǎn)生的過熱汽溫不穩(wěn)和減溫水量增加等負面影響不明顯。最后,對改造后鍋爐300MW負荷下不同運行工況進行數(shù)值計算,計算結(jié)果表明,不同磨煤機組合運行時,鍋爐均能實現(xiàn)穩(wěn)定運行,縮腰型配風方式是鍋爐改造后運行較優(yōu)的配風方式,過量空氣系數(shù)為1.2,SOFA風率為18%時,鍋爐運行較好。
[Abstract]:Coal is the most important primary energy in China. However, the combustion of coal has caused great damage to the environment. Dust, sulfur oxide and nitrogen oxide are the main sources of air pollution in China.The coal-burning of utility boilers accounts for more than half of the total coal consumption in China. Therefore, clean and efficient combustion of utility boilers has become the most important task of energy saving and emission reduction in China.China has basically solved the problem of low load and stable combustion of pulverized coal from utility boilers during the 10th Five-Year Plan period; it has concentrated on solving the problem of flue gas desulphurization and fuel saving by igniting fire during the 11th Five-Year Plan period; and it will focus on solving the problem of nitrogen oxide emission during the 12th Five-Year Plan period.At present, there are many technologies for reducing NO_x emission from utility boilers, including low NO_x combustion technology and catalytic reduction denitrification technology.From the comparison of comprehensive renovation cost, denitrification efficiency and later operation and maintenance cost, it can be seen that low NO_x combustion technology has advantages in controlling NO_x, which is a preliminary measure to be adopted in power plant boiler denitrification.In this paper, the flow, heat transfer and combustion in the boiler before and after the transformation of low nitrogen combustion are predicted by using the Fluent numerical calculation software, taking the 300MW tangential lean coal boiler of a power plant as the research object.The aim is to provide guidance for the actual retrofit and operation of the power plant after revamping.Firstly, the development of low nitrogen combustion technology at home and abroad is briefly introduced.Secondly, the mathematical model used in this paper is introduced.Then, using Fluent software to simulate the working conditions of 80% load and 60% load of 100% load before and after revamping, to study the distribution change of flow field, temperature field and component field in the furnace, and to verify the feasibility of the retrofit scheme.The results of preliminary acceptance test and calculation are compared and analyzed.The results show that the numerical results are in good agreement with the experimental results.After low NO_x combustion, the boiler combustion efficiency is low, the carbon content of fly ash is on the high side, and the high NO_x emission concentration is greatly improved.At the same time, the unsteady superheated steam temperature and the increase of cooling water are not obvious.Finally, the numerical calculation of the boiler under different operating conditions under 300MW load shows that the boiler can operate stably under the combined operation of different coal mills.The reduced waist type air distribution mode is the best way for boiler operation after retrofit. When the excess air coefficient is 1. 2 and the sofa air ratio is 18, the boiler runs better.
【學位授予單位】：華北電力大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TM621.2

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本文編號：1693627