600MW旋流对冲锅炉不同负荷下的优化模拟

发布时间：2018-10-22 20:28

【摘要】：在相当长的时间内,煤电仍是全球的主力电源。随着环境和能源问题的日益突出,国家出台严格的环保标准,燃煤电厂遭遇到前所未有的技术挑战。煤电企业在满足环保要求的巨大代价下如何寻找经济性,节能运行技术就显得尤为重要。本文以国电大同二电厂600MW对冲燃烧锅炉作为研究对象,通过燃烧数值模拟分析其燃烧特性,寻找不同负荷下的最优操作量,以提高锅炉的运行经济性。通过前处理软件Gambit建立几何模型并划分网格,采用计算流体力学商用软件Fluent进行模拟计算,生成煤粉颗粒报告,并采用CFD-POST进行后处理分析,获取各工况下速度场、温度场、各组分场。首先,通过现场试验获取各负荷下运行参数,以550MW工况为对比工况,验证模型的正确性。在燃烧模拟验证基础上,研究锅炉燃烧优化。不同负荷下的燃烧优化变量有:燃烬风率、上下层燃烬风比、燃烬风内外风比。燃烧优化研究基于各变量单因素变化下进行。结果表明:当燃烬风率增大时,主燃区欠氧加剧,不完全燃烧程度增加,使煤粉燃烬率降低,同时也会减少NO_x的生成;上、下层燃烬风比增大时,使燃烬风混入主烟气晚,未燃碳在燃烬区不能充分燃烬,使颗粒燃烬率降低,同时空气分级的加强,使得NO_x生成量减少;当燃烬风内外风比变小时,因为其对燃烬风与主烟气混合的影响,燃烬率会先变高后变小。基于各个负荷下的燃烧优化模拟,综合考虑燃烬效率与NO_x生成量之间的相互制约性,本文给出了各操作变量在相应负荷下的优化区间。
[Abstract]:For quite a long time, coal power is still the main power supply in the world. With the increasingly prominent environmental and energy problems and strict environmental standards, coal-fired power plants face unprecedented technical challenges. It is very important for coal power enterprises to find the economy under the huge cost of meeting the environmental protection requirements. In this paper, the 600MW combustion boiler of Datong No.2 Power Plant is taken as the research object. The combustion characteristics of the boiler are analyzed by numerical simulation of combustion, and the optimal operating quantity under different loads is found to improve the operation economy of the boiler. The geometric model is built up by pre-processing software Gambit, and the mesh is divided into meshes. The simulation calculation is carried out by using the commercial software Fluent of computational fluid dynamics, and the report of pulverized coal particles is generated. The velocity field and temperature field under various working conditions are obtained by using CFD-POST for post-processing analysis. Each part of the field. First, the operation parameters under each load are obtained by field test, and the correctness of the model is verified by comparing the 550MW working conditions. On the basis of combustion simulation and verification, the combustion optimization of boiler is studied. The combustion optimization variables under different loads are as follows: cinder rate, the ratio of upper and lower layer to air, and the ratio of internal and external air to cinder. The combustion optimization is based on the single variable variation. The results show that when the cinder air ratio increases, the oxygen deficiency in the main combustion zone increases, and the incomplete combustion degree increases, which results in the decrease of the pulverized coal cinder rate and the decrease of NO_x formation, and when the upper and lower combustion / air ratio increases, the cinder air will be mixed into the main flue gas later. The unburned carbon can not fully burn the embers in the burning embers, which reduces the burn-out rate of the particles, and at the same time, with the enhancement of the air grading, the amount of NO_x is reduced; when the ratio of the internal and external air to the cinder becomes smaller, because of its effect on the mixture of the cinder and the main smoke, The cinder rate increases first and then decreases. Based on the combustion optimization simulation under each load and considering the interaction between the burning efficiency and the NO_x yield, the optimal interval of each operating variable under the corresponding load is given in this paper.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM621.2

【参考文献】