高灰熔点煤高温下煤焦CO_2/水蒸气气化反应特性的实验研究

Experimental Study on Gasification Reaction Characteristics of Chinese High Ash Fusion Temperature Coal With CO_2 and Steam at Elevated Temperature

我国煤炭年产量中,1400℃以上的高灰熔点煤约占50%以上。为探索固态排渣方式的高灰熔点煤气流床气化,文中选出具有代表性的3种高灰熔点煤种和1种低灰熔点煤种,在TGA-51H型高温热天平上进行了煤焦—CO2和煤焦—水蒸气气化反应特性的实验研究,并利用SEM考察了气化条件下煤焦及灰的微观结构。实验结果表明:在煤焦—CO2/H2O反应过程中,反应速度明显表现出高温区域的扩散反应和低温区域的化学反应;无论在1273～1573K的低温区域,还是在高于1573K的高温区域,反应速率随燃料比的增加而减小;低灰熔点煤在高温条件下,气化反应速率随温度的升高变化不大,有时甚至略有下降;对于高灰熔点煤种其气化反应速率随温度的升高仍继续升高。

The high ash fusion temperature coal with TFT〉1400℃ was accounted for above 50% of annual coal production in China. For the purpose of using this kind of coal with entrained flow coal gasification with dry ash out, four typical coals which were selected with three high ash fusion temperatures and one low ash fusion temperature were gasified with carbon dioxide or steam by using TGA-51H with high temperature range, 1373-1673K. The ash and char were also studied with SEM under gasification conditions. The results show that the characteristics of reaction rate of coal char are separated into two different zones according to temperatures, one is pore diffusion control zone with high temperature, another is reaction control zone with tow temperature. Whether at low or high temperature, the gasification reaction rate decreased with increasing of the ratio of fix carbon to volatile. For chars with low ash fusion temperatures the reaction rate leveled off or even decrease a little as temperature increase while for chars with high ash fusion temperature the reaction rate would continue increasing.