【摘要】：我國目前的W火焰鍋爐燃燒技術(shù)均是從國外引進(jìn)，哈爾濱工業(yè)大學(xué)在對四個主要W火焰鍋爐燃燒技術(shù)深入研究后提出了“多次引射分級燃燒技術(shù)”，該技術(shù)在工業(yè)示范后取得了不錯的成果，，作為我國具有自主知識產(chǎn)權(quán)的Ｗ火焰鍋爐燃燒技術(shù)有著較高的研究價值。 本文以一臺350MW超臨界W火焰鍋爐作為研究對象，以其為原型搭建了1:13的冷態(tài)模化試驗臺。在試驗臺上進(jìn)行煙霧示蹤試驗優(yōu)化燃燒器噴口布置方式，還利用熱線風(fēng)速儀測量爐內(nèi)的空氣動力場，試驗研究得到以下結(jié)論： 當(dāng)乏氣噴口前置時，一次風(fēng)氣流不對稱，乏氣氣流在爐膛深度方向劇烈擺動，且出現(xiàn)了嚴(yán)重短路現(xiàn)象，爐內(nèi)流場不夠穩(wěn)定，將乏氣風(fēng)速提高以后，流場沒有明顯改善。當(dāng)乏氣與一次風(fēng)集中布置時，拱上氣流沒有出現(xiàn)短路現(xiàn)象，拱上乏氣和一次風(fēng)氣流較穩(wěn)定，前后墻氣流對稱分布，但是氣流的剛性較強(qiáng)，下射深度大，有可能會沖刷冷灰斗。當(dāng)一次風(fēng)、乏氣間隔布置時，爐內(nèi)的拱上氣流對稱性和穩(wěn)定性都較好，下沖深度合適，沒有沖刷冷灰斗的現(xiàn)象。綜合考慮采用多次引射分級引射燃燒理念的一次風(fēng)、乏氣間隔排列的燃燒器布置是較為合理的。 通過二次風(fēng)和三次風(fēng)風(fēng)量配比的冷態(tài)調(diào)整試驗可以發(fā)現(xiàn)，在前后墻三次風(fēng)水平噴入爐膛內(nèi)的情況下，爐內(nèi)流場極易出現(xiàn)偏斜，在二次風(fēng)風(fēng)率為15%和25%時，爐內(nèi)的流場在冷灰斗拐角上部區(qū)域以及冷灰斗區(qū)域都是偏斜的，后墻氣流占據(jù)主導(dǎo)地位，對W火焰鍋爐的燃燒和安全運行是極其不利的；增大二次風(fēng)風(fēng)率到28.35%時可以減輕流場的偏斜，只在冷灰斗區(qū)域出現(xiàn)輕微流場偏斜；當(dāng)二次風(fēng)風(fēng)率增大到35%時，流場偏斜基本消除。 通過三次風(fēng)下傾工況下的爐內(nèi)空氣動力場試驗表明，三次風(fēng)下傾角度為0o時下爐膛流場呈現(xiàn)明顯的不對稱性，后墻側(cè)的氣流占據(jù)了主導(dǎo)地位，將使前墻側(cè)煤粉氣流燃燒行程變短，煤粉在爐內(nèi)停留時間短，飛灰含碳量升高，從而降低了鍋爐效率；當(dāng)三次風(fēng)下傾角度為20o和30o時，爐內(nèi)呈現(xiàn)出規(guī)則的W型流場，前后墻側(cè)氣流在下行過程中遇到三次風(fēng)，兩股氣流混合后繼續(xù)下行一段到冷灰斗中部位置后轉(zhuǎn)折上行，延長了煤粉顆粒的燃盡行程，這對提高鍋爐效率是有利的。從爐內(nèi)水平截面的速度分布來看，三次風(fēng)下傾角度為20o的工況速度的對稱性好于三次風(fēng)下傾角度為30o的工況，因此建議三次風(fēng)下傾角度為20o。
[Abstract]:At present, the combustion technology of W-flame boiler in China is imported from abroad. Harbin University of Technology has put forward the "multi-ejection staged combustion technology" after deeply studying the combustion technology of four main W-flame boilers. The technology has achieved good results after industrial demonstration. As a W flame boiler combustion technology with independent intellectual property rights in China, it has high research value. In this paper, a 350MW supercritical W flame boiler is taken as the research object, and the 1:13 cold model test bench is built with it as the prototype. The smoke tracer test was carried out on the test bench to optimize the burner nozzle layout, and the aerodynamic field in the furnace was measured by using a hot wire anemometer. The primary air flow is asymmetrical, and the flow field is not stable enough because of the severe short circuit and the sharp swing of the air flow in the furnace depth. The flow field does not improve obviously after the increase of the air velocity of the spent gas. There is no short circuit in the air flow on the arch when the air is concentrated with the primary air, the air flow on the arch is stable and the air flow on the front and back wall is symmetrical, but the air flow is more rigid and the depth of the downfire is large, so the cold ash bucket may be washed away. When the primary air and the spent air interval are arranged, the airflow symmetry and stability of the arch in the furnace are better, the depth of the downflow is suitable, and there is no phenomenon of scouring the cold ash bucket. Considering the primary air with multiple ejection stages, the arrangement of burner with spent gas interval is reasonable. Through the cold state adjustment test of the ratio of secondary air and tertiary air volume, it can be found that the flow field in the furnace is prone to skew when the horizontal air of the front and rear walls is injected into the furnace, and the secondary air rate is 15% and 25%, respectively. The flow field in the furnace is skewed in the upper area of the corner of the cold ash hopper and the area of the cold ash bucket, and the air flow on the back wall occupies the dominant position, which is extremely unfavorable to the combustion and safe operation of the W-flame boiler. When the secondary air rate is increased to 28.35, the deflection of the flow field can be alleviated, only a slight deflection of the flow field appears in the area of the cool ash hopper, and when the secondary air rate increases to 35, the deflection of the flow field is basically eliminated. The experimental results of aerodynamic field in the furnace under the condition of triple-air downdip show that the flow field of the furnace shows obvious asymmetry when the downdip angle of the third air is 0 o, and the airflow on the back wall occupies the dominant position. The combustion stroke of pulverized coal flow on the front wall side will be shortened, the residence time of pulverized coal in the furnace will be shorter, the carbon content of fly ash will be increased, and the boiler efficiency will be reduced. When the downdip angle of the third air is 20 o and 30 o, the regular W-shaped flow field will appear in the furnace. The front and rear wall side air encountered three times air in the downgoing process, and the two airflow mixing continued to the middle of the cold ash bucket and then turned upward, which prolonged the burnout stroke of pulverized coal particles, which was beneficial to improve the boiler efficiency. According to the velocity distribution of horizontal section in the furnace, the symmetry of the velocity of the third air downdip angle is better than that of the third air downdip angle of 30 o, so it is suggested that the third air downdip angle should be 20 o.
【學(xué)位授予單位】：哈爾濱工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TK229.2;TK226.1

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