【摘要】：煤炭資源一直在我國的工業(yè)發(fā)展中扮演很重要的角色,無煙煤以及貧煤在煤炭總量中所占比例很大,因此近些年我國電廠陸續(xù)采用W型火焰燃燒技術的相關鍋爐,專門用于燃燒無煙煤。W型火焰鍋爐雖然有燃燒效率高等一系列優(yōu)點,但是暴露出的結構復雜、NO_x排放量高、燃燒穩(wěn)定性差等問題一直制約和影響W型火焰鍋爐的發(fā)展。引入復合燃燒技術以及復合鍋爐改造技術的方案是改進W型火焰鍋爐的不錯的選擇。本文針對某廠350MW亞臨界W型火焰鍋爐進行復合鍋爐技術改造,采用調整冷灰斗傾角,在下方續(xù)接鼓泡流化床的方案,充分利用流化床的穩(wěn)定燃燒、脫硫效率高、負荷調節(jié)范圍大等優(yōu)勢彌補W型火焰鍋爐不足。由于時間和資金問題,現階段只針對復合鍋爐進行數值模擬計算,研究分析W型煤粉-流化床復合鍋爐的流場特性以及異相反應的燃燒特性。本文使用歐拉-歐拉雙流體等模型,在原W型火焰鍋爐配風不變的情況下,模擬選取3個不同流化速度,研究流化床中不同大小流化速度對W型煤粉-流化床復合爐的流場特性的影響。通過分析不同工況的中心截面的流場和濃度場分布,流化速度可以影響到“W”型氣流的形成、空間位置的高低以及流場的對稱性。通過觀察三次風口橫截面空氣、小顆粒的速度云圖,可以更直觀地分析“W”型氣流的位置變化;通過在不同高度截線分析,研究空氣、不同粒徑的顆粒的濃度分布和速度分布,從而推出合理工況以及不同流化速度對整個流場的影響;在流場合理的工況中,截選多個橫截面,觀察分析整個復合爐的流場特性。選取流化床流化速度為1.3m/s的工況,保持配風風率不變,只改變三次風下傾角度,模擬選擇下傾角度為0°、15°、30°、45°和60°一共五個工況,研究分析三次風傾角對復合爐流場的影響。通過對比五個工況中心截面上的濃度、速度分布,得出流場分布左右對稱的三次風傾角。通過分析下行速度衰減曲線以及不同高度截線上的速度分布,進一步研究三次風傾角對復合爐流場的影響。針對W型煤粉-流化床復合爐內燃燒模擬計算,先是對燃燒反應模型的簡化和設計,簡化之后的燃燒過程主要是碳顆粒與氧氣、二氧化碳進行的異相反應,并編寫UDF控制化學反應速率。選用流化速度為1.3m/s的工況,設置合理的邊界條件進行燃燒模擬計算。選取爐膛中心截面研究分析流場、溫度場和濃度場的分布。三次風中心截面上的速度和溫度分布反映出三次風口的流場分布和燃燒狀況。選取三個不同截面上的中軸線上點的數據分析爐內溫度、速度和濃度分布。同時又在復合爐三個不同區(qū)域選取不同高度的截線,分別研究W型火焰鍋爐、流化床以及兩者之間的過渡區(qū)域內的速度和溫度分布。
[Abstract]:Coal resources have been playing a very important role in the industrial development of our country, anthracite and lean coal account for a large proportion of the total coal, so in recent years, power plants in China have adopted W-type flame combustion technology of related boilers. Although it has a series of advantages, such as high combustion efficiency and so on, the problems such as high NOx emission and poor combustion stability have been restricted and affected the development of W-type flame boiler. It is a good choice to improve W type flame boiler by introducing compound combustion technology and retrofitting technology of composite boiler. In this paper, the 350MW subcritical W type flame boiler of a certain factory is reformed with composite boiler technology. The scheme of adjusting the inclination of the cold ash bucket and connecting the bubbling fluidized bed below is adopted to make full use of the steady combustion of the fluidized bed and the desulfurization efficiency is high. The wide range of load regulation makes up for the shortage of W-type flame boiler. Due to the problem of time and fund, numerical simulation is carried out only for the composite boiler at this stage, and the characteristics of the flow field and the combustion characteristics of the heterogeneous reaction of the W-type coal-fluidized bed composite boiler are studied and analyzed. In this paper, Euler-Euler two-fluid model is used to simulate three different fluidization velocities under the condition that the distribution of air for the original W-type flame boiler is invariable. The effect of different fluidization rates on the flow field characteristics of W-type coal-fluidized bed composite furnace was studied. By analyzing the distribution of the flow field and concentration field of the central section under different working conditions, the fluidization velocity can affect the formation of "W" type airflow, the height of the space position and the symmetry of the flow field. By observing the velocity cloud diagram of the cross section of the third tuyere and the small particles, the position change of the "W" type airflow can be analyzed more intuitively, and the air can be studied by the section analysis at different heights. The distribution of concentration and velocity of particles with different particle sizes is used to deduce the influence of reasonable working conditions and different fluidization rates on the whole flow field, and in the reasonable working condition of the flow field, several cross-sections are intercepted and the flow field characteristics of the whole composite furnace are observed and analyzed. The fluidized bed fluidization velocity is selected as 1.3m/s condition, the air distribution rate is kept constant, and the downdip angle of the tertiary air is changed only. The downdip angle of 0 擄15 擄30 擄30 擄45 擄and 60 擄is selected in the simulation. The influence of the third air inclination angle on the flow field of the composite furnace is studied and analyzed. By comparing the concentration and velocity distribution on the central section of the five working conditions, the symmetrical distribution of the flow field and the third wind inclination angle are obtained. By analyzing the downlink velocity attenuation curve and the velocity distribution on different height sections, the influence of the third air inclination angle on the flow field of the composite furnace is further studied. In view of the combustion simulation calculation in W-type coal-fluidized bed composite furnace, the combustion reaction model is simplified and designed, and the combustion process after simplification is mainly the heterogeneous reaction of carbon particles with oxygen and carbon dioxide. The chemical reaction rate was controlled by UDF. The fluidization velocity is selected as 1.3m/s, and reasonable boundary conditions are set to simulate combustion. The distribution of flow field, temperature field and concentration field is analyzed by selecting the central section of furnace. The velocity and temperature distribution on the section of the tertiary air center reflects the distribution of the flow field and the combustion state of the tertiary air outlet. The temperature, velocity and concentration distribution in the furnace were analyzed by selecting the data of three points on the axis of three different sections. At the same time, the velocity and temperature distribution in the W-type flame boiler, fluidized bed and the transition zone between them were studied by selecting different section lines in three different regions of the compound furnace.
【學位授予單位】：哈爾濱工業(yè)大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TM621.2

【參考文獻】

相關期刊論文 前10條

1 呂太;王奇;;W火焰鍋爐狹縫式燃燒器燃燒特性研究[J];熱力發(fā)電;2014年06期

2 楊晨;趙麗;何航行;;600MW超臨界W火焰鍋爐燃燒特性及水冷壁分布參數混合模擬[J];熱科學與技術;2014年02期

3 楊麗;;中國煤炭科技發(fā)展現狀及展望[J];潔凈煤技術;2012年03期

4 吳貴輝;;我國能源形勢及發(fā)展對策[J];中國工程科學;2011年04期

5 劉炯天;;關于我國煤炭能源低碳發(fā)展的思考[J];中國礦業(yè)大學學報(社會科學版);2011年01期

6 趙劍峰;;低碳經濟視角下煤炭工業(yè)清潔利用分析及政策建議[J];煤炭學報;2011年03期

7 曹湘洪;;實現我國煤化工、煤制油產業(yè)健康發(fā)展的若干思考[J];化工進展;2011年01期

8 ;Drag models for simulating gas solid flow in the turbulent fluidization of FCC particles[J];Particuology;2009年04期

9 裴西平;;中國無煙煤生產、消費及進出口分析[J];中國煤炭;2009年06期

10 周建軍;王炯;冉景煜;蒲舸;張力;唐強;;在CFB鍋爐中煤粉不同噴入位置對爐內固相運動特性的影響[J];動力工程;2007年05期

相關博士學位論文 前2條

1 況敏;斗巴W火焰鍋爐及多次引射分級燃燒技術研究[D];哈爾濱工業(yè)大學;2012年

2 李清海;層燃—流化復合垃圾焚燒爐燃燒與排放研究[D];清華大學;2007年

相關碩士學位論文 前2條

1 徐鵬飛;煤粉—流化床復合燃燒數值模擬[D];哈爾濱工業(yè)大學;2013年

2 郭玉泉;W火焰鍋爐燃燒及運行特性試驗研究[D];山東大學;2006年

，

本文編號：2170053