【作者】 秦岭；

【导师】 周俊虎； 杨卫娟；

【作者基本信息】 浙江大学 ， 热能工程， 2006， 硕士

【摘要】 能源与环境问题被公认为影响当今社会发展的两大问题。在能源的利用中，矿物燃料的燃烧要排放大量的污染物，如NOx和SO₂等，其中NOx是大气的主要污染物质之一。我国是一个燃煤大国，其中火电耗煤量占相当大一部分，控制好电站锅炉的燃烧与污染物排放对人类可持续发展有很重要的意义。 本论文以国华北京热电分公司410t／h四角切圆燃煤锅炉为研究对象，首先进行了锅炉低NOx优化运行的试验研究；并通过Fluent数值模拟对其进行了深入的研究，计算结果与实际情况吻合较好，同时提出将上一次风上移作为再燃的改造方案，并对改造后的情况进行模拟预测，得到改造后工况运行优于现行工况。 首先是锅炉的优化运行研究，它是在对锅炉的各种运行工况测试数据作了分析后得出的，结果显示：对于现有的锅炉，完全可以通过改变它的配风及给粉参数来优化锅炉的运行，在优化了的工况中，不但氮氧化物排放量有所降低，而且锅炉效率也有所提高。虽然对于每一台锅炉，燃用不同的煤粉都存在着相对较优的配风给粉方式，但文章中还是可以得到一种相对普遍的优化方式，或者说是优化思路。 其次主要涉及了锅炉现运行情况下的模拟计算，详细的研究了计算模型网格划分的问题，对网格的画法、生成的质量、以及网格形式对计算结果的影响等方面进行了研究，得出了一种对计算比较有利的网格形式。通过Fluent计算，将结果与锅炉运行试验数据进行对比，其结果与实际值具有可比性，因此采用数值计算的方法可以指导实际工作的进行。 最后从理论上阐述了设计的思路与方法，并提出具体的设计方案，即将锅炉上一次风喷口上移作为再燃喷口，而将上二次风喷口上移也作为燃尽风喷口。重点描述改造设计后的运行模拟情况，通过模拟的手段对炉内的流场、压力场、温度场、组分场，及NOx生成情况进行了分析。计算结果显示，改造后的锅炉运行稳定，流场实际切圆均在控制范围内，没有出现贴壁燃烧的情况；炉内温度场均匀连续，锅炉燃烧完全，从锅炉模型出口处检测得的可燃物完全燃尽，改造后预测锅炉燃烧状况较好；在采用了再燃技术后，NOx排放量有显著降低，脱硝率为51.07％，并且可以直观的看出采用再燃的效果，模拟计算显示锅炉改造设计比较成功。更多还原

【Abstract】 Energy and pollution were important factors affecting society development. The combustion of fuels generate SO₂ and NO_x emissions, which can lead to serious atmosphere pollution .Coal was the important fuel for china , and most of coal was used in power plant . Control of the combustion and pollution of power plant were important for the sustainable development of human society.A Corner-tangential-boiler of 410t/h in Guohua Beijing thermal powerplant was studied in the thesis. Firstly, optimizing operation was carried on boiler for de-NOx emission; secondly, numerical simulation was made by Fluent software, the calculation results were consistent with experiments. The retrofit scheme of reburn was put out which ascended the upper primary wind. The operation simulation of retrofit system revealed that conditions after reconstruction excelled than the old.Optimizing operation of boiler was studied by analyzing test data of several boiler conditions. The results revealed that adjustments of air distribution and feed powder could optimize the operation of boiler. After optimizing operation, the quantum of NOx decreased and the boiler efficiency increased, the most optimizing air distribution and feed powder was resist for every boiler. An optimizing method was put out in the thesis.The simulation calculation of boiler operation was discussed in detail. Numerical simulation is based on fine grid. The study focused on the aspects such as grid-build, grid quality and its influence on calculation. A fine grid was put out in thesis which could benefit the convergence. The calculation results were consistent with the experiments data. So the simulation results could guide the practical operation.Finally the thought and method of design were expatiated from theory. The feasible design was put out which ascended the upper primary wind as reburning-spout and ascended the upper secondary wind as OFA. The simulation results were discussed in detail about fluid flow, pressure field, temperature filed, the distribution of species, and the production of NOx. After retrofitting, the boiler operated stably and the circle radius was under control as there is not combustion sticking to the wall’s surface; the temperature field was uniformity; complete combustion was reached as the carbon in fly was not found in simulation results; the emission of NOx decreased obviously and the reduction efficiency was 43.3%. To sum up, the simulation results revealed that the retrofit system was successful.更多还原