分解炉内燃烧与NO_x生成的数值模拟研究

发布时间：2018-01-20 10:10

本文关键词： 分解炉 NO_x 分级燃烧数值模拟三次风　出处：《西南科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：分解炉是新型干法水泥生产工艺中重要的热工设备,也是预分解窑技术中一个承前启后的工艺节点。预热器下来的生料、回转窑内的烟气、三次风、煤粉以及送煤风均要进入分解炉,这一方面直接体现出分解炉操作的复杂性,另一方面也说明分解炉是否运转良好与它们息息相关。分解炉内生成的NO在水泥生产污染物NOx排放中占比较大,因此能否显著降低分解炉内NO生成量就显得尤为重要。分解炉内有三次风、窑气以及送煤风等气流进入,而且它们的进口大多集中在分解炉下部,这就造成了分解炉局部流场的复杂。此外,分解炉内燃料燃烧产生的烟气以及生料分解释放的二氧化碳也会加强分解炉内流场的复杂性。这直接表明研究分解炉内生成NO过程中客观存在较多变量。本文在总结前人分解炉内燃烧与NO生成研究的基础上进行进一步研究。对分解炉三次风等重要工艺参数进行研究,研究发现:随着三次风风速越来越大,分解炉NO生成量越来越高;随着三次风温度越来越高,分解炉NO生成量越来越低;分解炉NO生成量在三次风氧含量为19%最高,到分解炉出口时五种三次风氧含量的分解炉NO含量相差不大。本文对分解炉喷煤管不同安装方位进行研究,研究发现:喷煤管中心线与YZ面夹角越大,在分解炉锥部形成气流交汇区越大;喷煤管安装方位与YZ面夹角为51°和68°时送煤风气流会在分解炉锥部形成环流区,且68°时形成的环流区较大。喷煤管安装方位与YZ面夹角为17°时有较高的燃料燃烧强度,较高的NO浓度。夹角为51°不利于燃料燃烧,夹角为34°附近时,有良好的燃料燃烧强度以及较低的NO浓度。本文对分解炉燃料分级进行分析研究,研究发现:分解炉喷煤管分煤比例为1:9时,燃料主燃区内,窑气含氧量越低分解炉内NO生成量越高;分解炉喷煤管分煤比例为2:8时,窑气氧含量为0.3%时在燃料主燃区内温度较高;分解炉燃料主燃区内NO含量在窑气氧含量为0.6%时最高;分解炉喷煤管分煤比例为3:7时,分解炉内氧含量在燃料余燃区内窑气氧含量为0.6%时较高,分解炉内NO生成量在窑气氧含量为0.6%时在燃烧主燃区内较高,在三种喷煤管分煤比例中不同窑气氧含量下的分解炉出口NO含量相差不大。分解炉加入生料会通过影响燃料燃烧强度来影响分解炉内NO生成。通过本文对分解炉三次风主要工艺参数、分解炉喷煤管安装方位以及分解炉燃料分级燃烧对分解炉生成NO的研究为预分解窑技术领域提供了较多的实验样本,同时也为节能减排分解炉类型设计及改造提供了实用的参考价值。
[Abstract]:Calciner is an important thermal equipment in the new dry cement production process, and it is also a process node in precalciner technology, raw material from preheater, flue gas from rotary kiln, and tertiary air. Pulverized coal and coal air must enter the calciner, which on the one hand directly reflects the complexity of the operation of the calciner. On the other hand, it also shows that whether the calciner works well is closely related to them. No produced in the calciner accounts for a large proportion of the NOx emission from cement production. Therefore, it is very important to reduce the production of no in the calciner. There are three air flow in the calciner, kiln gas and coal feed air, and most of their imports are concentrated in the lower part of the calciner. This results in the complexity of the local flow field in the calciner. Flue gas produced by combustion of fuel in calciner and carbon dioxide released by decomposition of raw materials will also enhance the complexity of flow field in calciner, which directly indicates that there are many variables in the process of no formation in calciner. On the basis of summing up the previous researches on combustion and no generation in calciner, some important technological parameters, such as tertiary air of calciner, were studied. It is found that with the increasing of the third wind speed, the no production of the calciner becomes higher and higher. With the increase of tertiary air temperature, no production of calciner becomes lower and lower. The no content of the calciner is the highest at the third air oxygen content of 19%, and the no content of the five kinds of decomposition furnace with the three air oxygen content at the outlet of the calciner is not different. The different installation orientation of the coal injection tube of the calciner is studied in this paper. It is found that the greater the angle between the central line of the coal injection pipe and the YZ plane, the larger the air flow intersection area formed in the cone of the calciner. When the angle between the installation orientation of the coal injection pipe and the YZ plane is 51 掳and 68 掳, the air flow will form a circulation area in the cone of the calciner. The fuel combustion intensity is higher and no concentration is higher when the angle between the installation azimuth of the coal injection pipe and the YZ plane is 17 掳, and the angle is 51 掳is not good for the fuel combustion. When the angle is about 34 掳, there is good fuel combustion intensity and low no concentration. In this paper, the fuel classification of calciner is analyzed and studied. It is found that the coal separation ratio of coal injection pipe of calciner is 1: 9. In the fuel main combustion zone, the lower the oxygen content of kiln gas, the higher the no production in calciner. When the coal injection pipe of calciner is 2: 8, and the oxygen content of kiln is 0.3, the temperature is higher in the fuel main combustion zone. The content of no in the main combustion zone of calciner is the highest when the oxygen content of kiln gas is 0.6; When the coal injection pipe of the calciner is 3: 7, the oxygen content in the calciner is higher when the oxygen content in the kiln is 0.6 in the fuel residual combustion zone. The production of no in the calciner is higher in the main combustion zone when the oxygen content in the kiln is 0.6. The no content at the outlet of the calciner under different kiln gas and oxygen content has little difference among the three kinds of coal injection pipe. Adding raw material to the calciner will influence the no formation in the calciner by influencing the burning intensity of the fuel. Main technological parameters of tertiary air in pyrolysis furnace. The research on the installation orientation of the coal injection tube of the calciner and the formation of no from the calciner by staged combustion of the calciner fuel provides more experimental samples for the technical field of the precalciner kiln. At the same time, it also provides practical reference value for the type design and transformation of energy saving and emission reduction calciner.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ172.6

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