氧化铁对煤流化床热解特性影响的实验研究

Experiments on the effects of Fe_2O_3 on coal during fluidized bed pyrolysis process

为了分析Fe_2O_3对煤热解特性的影响,以准格尔烟煤为原料,在小型流化床反应器上,温度范围为500～800℃内,对添加Fe_2O_3质量分数分别为0%、5%、10%、20%的煤样进行热解,并对其热解产物产率和气体组分进行分析。结果表明:Fe_2O_3在整个温度范围内会明显降低焦油产率,却促进热解水的产生。Fe_2O_3对半焦和气体的影响特性与温度有关:在低温区,Fe_2O_3会催化胶质体的芳构化作用和缩聚反应,抑制胶质体的裂解反应,从而增加半焦产率,减小挥发分(热解气体和焦油)产率;而在高温区,半焦会和Fe_2O_3发生反应,使得CO和CO_2产率上升;另外,Fe_2O_3会明显改变热解气组分。温度较低时,Fe_2O_3会促进煤中的含氧自由基重新结合,抑制CO和CO_2的生成,随着温度的升高,Fe_2O_3与多种还原性气体(CO、H_2、CH_4)发生氧化还原反应,多种反应竞争下,使得Fe_2O_3对各气体的促进程度不同。

Zhungeer bituminous coal was selected as experimental materials in order to study the effect of Fe 2O 3 on pyrolysis characteristic of coal. The pyrolysis experiments of the raw coal loaded mass fraction of 0%, 5%, 10%, 20% of Fe 2O 3 were carried out in a small fluidized bed reactor, within the temperature range from 500 ℃ to 800 ℃.The results showed that, at the temperature range from 500 ℃ to 800 ℃,Fe 2O 3 could obviously reduce tar yield, but increase water yield. The effects of Fe 2O 3 on char and gas were relative to temperature. At the temperature between 500℃ and 600 ℃, Fe 2O 3 would catalyze the aromatization and polycondensation of the colloid and inhibit the cracking reaction of the colloid, thus increasing the char yield and reduce the volatiles(including gas and tar) yield. At the temperature between 700℃ and 800℃, the semi coke reacts with Fe 2O 3, therefore increasing CO and CO 2 yield. In addition, Fe 2O 3 would significantly change the pyrolysis gas components. When the temperature was low, Fe 2O 3 would promote the recombination of oxyradical, so the formation of CO and CO 2 was suppressed. And with temperature increasing, Fe 2O 3 would react with some kinds of reducing gas, such as CO、H 2 and CH 4, so the degree of promotion varied.