A double air stage downdraft fixed-bed gasification system with the capacity of 25 kg/h, including the type, construction, size of the gasifier, and the device of tar sampling, the key parameter of blower fan, draft fan and the char discharge system were designed. The height and inner diameter of the gasifier was 2 683 mm and 350 mm, respectively. The designed flow rate of draft fan and blower fan were both 60 m3/h. Based on the result of cold and hot state experiments, this designed gasification system was well established and could totally reached the design goal. Compared to the result from the single air stage gasification, the temperature inside the gasifier was remarkably increased, and the content of the combustible gas component in the producer gas and the lower heating value of producer gas was increased, while the tar content in the producer gas was decreased by the double air stage gasification method.%开发了一套原料处理量为25 kg/h的两步进气下吸式固定床气化系统,并对两步进气直筒形(stratified)下吸式固定床气化炉的炉型、结构和主体尺寸以及焦油检测系统进行了设计.对鼓风机、引风机、出炭螺旋等关键部件的参数进行了计算.气化炉整体高度为2 683 mm,气化炉有效内径为350 mm,所需引风量和鼓风量都是60 m3/h.采用木片为原料,通过冷态实验和热态实验对气化系统进行验证,验证了该气化系统完全满足设计和实验需要.通过对比两步进气和一步进气实验结果,发现两步进气法可有效提升炉体温度,显著提高可燃气中可燃气体组分含量和热值,并有效降低可燃气中焦油含量.
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