超低热值燃气多孔介质燃烧器燃烧特性的研究

发布时间：2018-10-17 14:03

【摘要】：本文是在原有的超低热值燃气多孔介质燃烧器的基础上进行优化改进。着重研究不同热值时,多孔介质积木式排列结构对燃烧器稳定燃烧的极限以及极限工况所对应的污染物排放的影响,力求通过对比不同的积木式排列结构所对应的燃烧极限来找到一种在热值适应性和低污染排放等方面综合性能比较突出的结构。本文的研究成果为超低热值气体的高效清洁利用提供了一条新的途径。本文通过数值模拟的方法依次探索了三种积木式内芯结构,分别为CAPM-A型、CAPM-B型和CAPM-C型。针对CAPM-A型内芯结构,我们还进行了试验研究并与相应的模拟结果进行了对比验证。在CAPM-A型内芯结构中,多孔介质的孔径从上游到下游成逐渐变小的趋势而CAPM-B型内芯结构与此正好相反。研究结果表明:CAPM-B型内芯结构的热值适应性较好,其能够燃烧最小热值为1.2MJ/Nm3的气体,而CAPM-A型内芯结构对应的最小热值为1.4MJ/Nm3;此外在稳定燃烧区域的范围和低污染排放方面,CAPM-B型内芯结构的性能也都优于CAPM-A型内芯结构。以上结论进一步说明了积木式排列的多孔介质内芯结构在孔径上应该遵循从上游到下游逐渐变大的趋势。考虑到贴近内筒壁面侧的多孔介质的孔径会影响到对内外筒间新鲜燃气的预热效果,我们在CAPM-B型内芯结构的基础上又探索了CAPM-C型内芯结构,其与CAPM-B型内芯结构的区别在于贴近壁面处的多孔介质要比相应的CAPM-B型的多孔介质的孔密度小5PPI。研究结果表明:CAPM-C型内芯结构的热值适应性较差,其能够燃烧最小热值为1.5MJ/Nm3的气体;此外在稳定燃烧区域的范围和低污染排放方面,CAPM-B型内芯结构的性能也都优于CAPM-C型内芯结构。对于各个内芯结构而言:不论是回火极限还是脱火极限,极限工况的功率随着热值的增大而增大;热值一定时,脱火极限的功率大于相应的回火极限;介于脱火极限和回火极限之间的稳定燃烧区域的范围随着热值的提高而变大;热值一定时,回火极限对应的CO排放量大于脱火极限时的CO排放量;CO的排放量随着燃气热值的减小而大大增加。对比各个内芯结构的结果表明:在其它条件一致时,CAPM-B型在热值适应性、稳定燃烧区域的范围和低污染排放上综合性能优于其它排列结构。采用CAPM-B型内芯结构时,超低热值燃气多孔介质燃烧器稳定燃烧对应的最小热值为1.2MJ/Nm3,相应的能够满足稳定燃烧的的最小燃烧强度为61.15 kW/m2,对于燃烧强度大于61.15 kW/m2的工况只要选用合适热值的气体就都能在此多孔介质燃烧器中实现稳定燃烧。
[Abstract]:This paper is based on the original ultra-low calorific value gas burner in porous media. The influence of the building block arrangement structure of porous media on the combustion limit of the burner and the pollutant emission corresponding to the limit condition are studied. By comparing the combustion limits of different building block arrangement structures, we try to find a structure with outstanding comprehensive performance in the aspects of heat adaptability and low pollution emission. The results of this paper provide a new way for the efficient and clean utilization of ultralow calorific gases. In this paper, three kinds of building block core structures, CAPM-A type, CAPM-B type and CAPM-C type, are explored by means of numerical simulation. For the inner core structure of CAPM-A, we have also carried out the experimental research and compared with the corresponding simulation results. In CAPM-A core structure, the pore size of porous media decreases gradually from upstream to downstream, whereas CAPM-B core structure is the opposite. The results show that the heat value of CAPM-B core structure is good, and it can burn gas whose minimum calorific value is 1.2MJ/Nm3. The minimum calorific value of CAPM-A core structure is 1.4MJ / Nm3.In addition, the performance of CAPM-B core structure is better than that of CAPM-A core structure in terms of stable combustion region and low pollution emission. The above conclusion further indicates that the core structure of the porous media with block arrangement should follow the trend of increasing from upstream to downstream in pore size. Considering that the pore size of porous media close to the wall of the inner cylinder will affect the preheating effect of fresh gas between the inner and outer cylinders, we have explored the CAPM-C core structure on the basis of the CAPM-B inner core structure. The difference between it and the core structure of CAPM-B is that the pore density of the porous media near the wall is 5 PPI less than that of the corresponding CAPM-B type. The results show that the heat adaptability of CAPM-C core structure is poor, and the minimum calorific value of 1.5MJ/Nm3 gas can be burned. In addition, the performance of CAPM-B core structure is better than that of CAPM-C core structure in terms of stable combustion region and low pollution emission. For each core structure, whether it is tempering limit or de-tempering limit, the power of limit condition increases with the increase of calorific value, the power of de-tempering limit is larger than corresponding tempering limit when calorific value is fixed. The range of stable combustion region between tempering limit and tempering limit increases with the increase of calorific value. The CO emissions corresponding to the tempering limit are larger than the CO emissions at the de-tempering limit, and the CO emissions increase with the decrease of the gas calorific value. The results of comparison of each inner core structure show that when other conditions are the same, the comprehensive performance of CAPM-B type is superior to that of other arrangement structures in the adaptability of calorific value, the range of stable combustion region and the low pollution emission. When adopting the inner core structure of CAPM-B, The minimum calorific value corresponding to the steady combustion of ultralow calorific value gas porous medium burner is 1.2 MJ / Nm ~ (3), and the corresponding minimum combustion intensity is 61.15 kW/m2, when the combustion intensity is greater than 61.15 kW/m2 if the appropriate calorific value is selected. The gas can be burned stably in this porous medium burner.
【学位授予单位】：河北工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ052.73

【相似文献】