Gilbert P, Ryu C, Sharifi V, Swithenbank J
Tyndall Centre, Department of Mechanical, Aerospace and Civil Engineering, University of Manchester, Manchester M60 1QD, UK.
Bioresour Technol. 2009 Dec;100(23):6045-51. doi: 10.1016/j.biortech.2009.06.041. Epub 2009 Jul 14.
The behaviour of pyrolysis vapours over char was investigated in order to maximise tar conversion for the development of a new fixed bed gasifier. Wood samples were decomposed at a typical pyrolysis temperature (500 degrees C) and the pyrolysis vapours were then passed directly through a tar cracking zone in a tubular reactor. The product yields and properties of the condensable phases and non-condensable gases were studied for different bed lengths of char (0-450 mm), temperatures (500-800 degrees C), particle sizes (10 and 15 mm) and nitrogen purge rates (1.84-14.70 mm/s). The carbon in the condensable phases showed about 66% reduction by a 300 mm long char section at 800 degrees C, compared to that for pyrolysis at 500 degrees C. The amount of heavy condensable phase decreased with increasing temperature from about 18.4 wt% of the biomass input at 500 degrees C to 8.0 wt% at 800 degrees C, forming CO, H(2) and other light molecules. The main mode of tar conversion was found to be in the vapour phase when compared to the results without the presence of char. The composition of the heavy condensable phase was simplified into much fewer secondary and tertiary tar components at 800 degrees C. Additional measures were required to maximise the heterogeneous effect of char for tar reduction.
为了开发新型固定床气化炉以实现焦油转化率最大化，研究了热解蒸汽在焦炭上的行为。木材样品在典型热解温度（500摄氏度）下分解，然后热解蒸汽直接通过管式反应器中的焦油裂解区。针对不同的焦炭床层长度（0 - 450毫米）、温度（500 - 800摄氏度）、粒径（10和15毫米）以及氮气吹扫速率（1.84 - 14.70毫米/秒），研究了可冷凝相和不可冷凝气体的产物产率及性质。与500摄氏度热解相比，在800摄氏度下，300毫米长的焦炭段使可冷凝相中的碳减少了约66%。随着温度升高，重可冷凝相的量从500摄氏度时约占生物质输入量的18.4重量%降至800摄氏度时的8.0重量%，生成了一氧化碳、氢气和其他轻分子。与不存在焦炭的结果相比，发现焦油转化的主要方式是在气相中进行。在800摄氏度时，重可冷凝相的组成简化为更少的二次和三次焦油成分。需要采取额外措施以最大化焦炭对减少焦油的非均相作用。
