【作者】 黄恒波；

【导师】 余兆祥；

【作者基本信息】 同济大学 ， 应用化学， 2008， 硕士

【摘要】 本研究根据圆筒型管式加热炉自身的特点和结构,结合四角切圆和旋流的燃烧方式,提出一种在螺旋向上的,旋流中央增加锥形的辐射墙来强化辐射传热的燃烧方式。通过搭建小型的圆筒型管式炉的小试装置进行了单直喷,四小直喷,旋喷的热态传热对比试验,在无换热介质的传热实验中,发现无论是大石油液化气流量还是小石油液化气流量,旋流燃烧的效果明显好于其它燃烧方式。在以水为换热介质的有载荷传热实验中,旋流燃烧方案仍然好于其它方案,水管的出水温度更高,排烟温度更低。通过对单直喷,四小直喷以及旋喷三种流动方式的冷态数值模拟,得到了三种不同流动方式的速度场,发现旋流喷射器的4个燃烧器以45°倾斜向上的布置,形成了旋转的涡旋,增强了燃料助燃空气的混合,同时稳定了气流,增加燃料和助燃气在炉膛内的停留时间。旋流燃烧器中辐射锥的设置起到了导流的作用,使得流体由中心向周围扩展,锥形的设计使得流体扩展的直径逐渐变大,同样起到增加流体在炉膛内停留时间的作用。通过对四小直喷和旋喷两种燃烧方式的热态三维数值模拟,发现试验测得炉膛内的不同位置设置测温点测得的温度垂直分布曲线与数值模拟得到的相同位置的温度分布曲线,曲线变化的趋势接近,出口烟气的温度值误差较小。通过对比两种不同燃烧方式的数值模拟结果,发现旋喷燃烧的温度场分布比短焰直喷的直流燃烧方式均匀,炉膛底部辐射锥的导流作用明显,火焰既没有舔到炉管,又使得高温烟气更接近四周的炉管,直接强化了炉膛中下部的传热。而旋流燃烧由于旋流产生的涡旋作用,不仅增加了燃料和助燃空气在炉膛中下部的停留时间,并且增加了高温烟气在炉膛内的停留时间,降低了排烟温度。更多还原

【Abstract】 A new way of swirling combustion was presented in this paper. A radiant tapered wall was placed in the center of the swirl in order to enhance the heat transfer.A compare experiment was made between traditional combustion method and the swirl combustion method. The result showed that the swirl played a more effective part in combustion. The heat transfer was improved in the middle and at the bottom of furnace and the temperature of outer smoke drops. The same result was also got using water as the heat transfer fluid.This paper also presented numerical simulation results of traditional and new swirling fluid flow. The velocity field showed that mixing homogeneity were improved, retention time of the fuel and air were extended by the swirl. The flow-guide characteristics of the tapered wall showed its superiority.Three dimensional numerical simulations of the four direct bottom up combustion and swirling combustion method were made for the radiant section of furnace. The results with the models were in well agreement with the measurements of temperature from top to down. The different methods were comparable. It was showed that temperature field distribution of the swirling method was much better.. The radiant tapered wall not only keep proper distance to the pipe, but also guide the high temperature gas around the pipe, so the heat transfer in the middle and at the bottom of the furnace was directly improved. The swirl also extend the high temperature smoke’s retention time at the top of the furnace, enhanced the heat transfer without question, and dropped the temperature of outer smoke.更多还原