煤加压富氢热解及半焦气化特性研究 - -

为研究加压固定床气化过程中热解区和气化区的反应,模拟固定床富氢气氛热解与半焦气化过程,利用加压富氢热解装置考察了压力、加热终温以及富氢比例对煤热解的影响,分析了各因素对热解影响的机理,以富氢气氛热解半焦为原料,通过加压热重分析仪进行试验研究,研究不同温度和不同热解半焦原料的条件下碳转化率与CO_2反应速率随时间的变化规律,分析富氢比例对气化反应活性的影响。结果表明:常压富氢气氛热解试验中,随着富氢比例的升高,提供大量H,H浓度增大,煤在热解过程中自由基会不断与H结合生成稳定组分,其中包括大量小分子的挥发物以及部分焦油析出,使半焦中挥发分降低0.69%,半焦收率降低4.8%;加压条件下半焦收率较高,半焦收率随压力的增大变化幅度不大,且没有明显规律,挥发分总体逐渐降低,但变化较小;随着终温的升高,挥发分析出量逐渐升高,伴随着挥发分析出,富氢氛围中的H将与自由基结合生成小分子结构而逸出,半焦收率与挥发分均逐渐降低;增加富氢比例能提高半焦的成熟程度,富氢比例由0增加到35%,H浓度增大,煤中小分子可迅速加氢生成挥发物,同时大分子也会加氢变为稳定结构,半焦挥发分降低了1.46%,半焦收率降低了2.50%;富氢热解能明显促进CO和CH_4的生成,在35%H_2时产量分别达到91.2和63.8 mL/g。由气化特性试验可知:提高气化反应温度,有助于提高富氢半焦与CO_2的气化反应性;富氢气氛与惰性气氛下热解半焦的气化反应活性相近,表明加氢热解能够提高焦油产率与焦油品质,同时对半焦的气化活性影响不大。 In order to study the reaction between the pyrolysis zone and the gasification zone in the pressurized fixed bed gasificationprocess,the pyrolysis and semi-coke gasification process of the fixed bed hydrogen-rich atmosphere was simulated,and the influence ofpressure,heating temperature and hydrogen-rich ratio on coal pyrolysis were investigated by the pressurized hydrogen-rich pyrolysis de-vice. The mechanism of the influence of various factors on pyrolysis was analyzed. The pyrolysis of semi-coke in hydrogen-rich atmospherewas used as raw material. The experimental study was carried out by pressurized thermogravimetric analyzer. The change of carbon conver-sion rate and CO_2 reaction rate with time under different temperature and different pyrolysis raw materials and the effect of hydrogen-richratio on gasification reaction activity were analyzed. The results show that in the atmospheric pressure hydrogen-rich atmosphere pyrolysistest,with the proportion of hydrogen rich increasing,a large amount of H are provided and the concentration of H is increased. During the pyrolysis process,the free radicals will continuously combine with H to form stable components. Including a large number of small mole-cules of volatiles and some tar precipitation,the volatiles in the semi-coke decrease by 0.69%,the semi-coke yield decreases by 4.8%.The semi-coke yield under the pressurized conditions is higher. The semi-coke yield with the increase of pressureis not obvious law. Thevolatile matter gradually decreases,but the change is small. With the increasing of the final temperature,the volatile yield gradually increa-ses in the hydrogen-rich atmosphere. H in hydrogen rich atmospherewill combine with free radicals to form a small molecular structure andescape,and the semi-coke yield and volatile matter will gradually decrease. Increasing the proportion of hydrogen richcan increase the ma-turity of the semi-coke,the proportion of