【作者】 李建中；

【导师】 周昊； 岑可法；

【作者基本信息】 浙江大学 ， 工程热物理， 2006， 硕士

【摘要】 锅炉燃烧系统是锅炉系统中最重要的部分，燃烧状态的好坏，直接影响电厂的经济效益。煤质煤灰熔点对锅炉结渣特性与热效率都有很大影响，很多国家都制定了以灰熔点来评判锅炉结渣特性的标准，国内有些电厂把灰熔点作为衡量煤质的重要指标。合理配比混煤的方法可以改变煤的灰熔点特性，对于保证锅炉的安全、经济运行具有重要意义。为了提高估算煤灰熔点的精度，采用支持向量机结合遗传算法对求解灰熔点问题进行了建模。将灰成分作为输入量，煤灰软化温度(ST)作为输出量，用试验数据对模型进行了校验，结果表明，支持向量机模型预测的最大相对误差和平均相对误差分别为：7.4％和0.678％，较精确的实现了对软化温度的预测。 煤粉分配器在运行中对空气和煤粉分配进行调节，实现了风粉分配由不可控制到有效控制，有效调整炉膛出口温度，避免或减轻炉内结渣，使锅炉在低负荷燃烧条件下的稳定燃烧能力大大加强。本文介绍了两相流的相关理论与知识，就气固多相流浓度测量技术进行了理论综述，并对现有的气固多相流浓度测量设备做了介绍。本文对本次试验中采用的光学波动法测量设备作了详细的介绍。本文运用fluent这个成熟的商业CFD软件，对入口段长度为1D，分叉管与弯管平行按装的工况进行气粉分配的数值模拟，并对模拟计算的结果进行了分析和评价。本文在大型两相流试验台架上进行了弯管出口管上的浓度分布试验及分又管内的的浓度分布试验，并对试验结果进行了分析与评价，指出当入口段小于5D时入口段长度对弯管与分叉管的平行按装的气粉分配的均匀性有很大的影响，但当分叉管与弯管垂直按装时，却能获得良好的分配效果。 最后，本文对本次研究进行了工作总结，得出了本次研究的结论，研究过程中可能存在的问题，并对今后工作的研究工作提出了要求。更多还原

【Abstract】 Combustion system is the most important part in boiler system. Economic benefit of power plant is affected by the state of boiler’s combustion. Coal ash fusion temperature has large influence on thermal efficiency and clinkering of boiler. Many countries constitute criterion with coal ash fusion temperature to judge propensity of clinkering. In our country, many power plants take coal ash fusion temperature as a very important parameter to estimate coal quality. Coal blending technology is helpful for boiler safe and economical operation. In order to improve the accuracy of the ash fusion temperature prediction. Support vector machine and genetic algorithms were combined to model the ash fusion temperature of coal blends. The chemical compositions of the coal ash were employed as inputs and the ash fusion temperature as output. The results show that the maximum and average relative predicting error were 7.4% and 0.678%, respectively. Support vector machine can find its application in the small sample training, its calculating speed is fast which can improve the real-time processing performance.Pulverized coal distributor effectively controls the distribution of pulverized coal and air, and adjusts the smoke temperature of the furnace outlet by adjusting the distribution of pulverized coal and air. Pulverized coal distributor also avoids or reduces propensity clinking, enhance the steady combustion ability under low load. This paper introduced the theory and knowledge about two phase flow, and summarized the techniques and instruments of measuring concentration of Gas-Solid multiphase flow. The instrument of optical wave method used in experiment was detailed introduced. A commercial CFD software fluent was used to numerical simulate the distribution of pulverized coal and air at the distance of 1D after the entrance under the condition of fork pipe and elbow are parallel installed. The result of this numerical simulate was analyzed and estimated in this paper. The experiments of testing concentration distribution in the fork pipe and in the export pipe of the fork pipe are carried out on large test board. The results of these experiments showed that distance has great influence on the even distribution of pulverized coal and air under the case of fork pipe and elbow are parallel installed when entrance shorter than 5D, but distribution of pulverized coal and air under the case of fork pipe and elbow are vertical installed is good.At last, this paper summarized the study works (include experiment and numerical simulate) and draw a conclusion, discussed some problems which may be existed in the research process, and give some advices on continual researches.更多还原