高灰煤小型流化床混合气催化气化研究

Investigation on catalytic gasification of high-ash coal with mixing-gas in a small-scale fluidized bed

在内径28 mm流化床中,对阳泉高灰煤在碱性催化剂(固碱和黏胶废碱液)作用下进行了混合气(空气/水蒸气)催化气化研究,两种碱性催化剂的适宜添加量均为6%.不加催化剂,气化温度830 ℃～900 ℃与900 ℃～920 ℃下,气化反应的表观反应级数n分别约为2/3与1/3;有催化剂(3%固碱)时,表观反应级数有两个明显的温度段,在830 ℃～860 ℃,催化气化的表观反应级数n=1;在860 ℃～920 ℃,催化气化的表观反应级数为n=1/3.

The experimental study on the Yangquan high-ash coal catalytic gasification with mixing-gas （air/ steam） by using solid alkali （sodium hydroxide） or waste liquid of viscose fiber as the catalyst in a small-scale fluidized bed with 28 mm i. d. was carded out. The loading saturation levels （LSL） of two catalysts in Yangquan high-ash coal are about 6%. Under the gasification temperature ranging from 830 ℃ to 900 ℃ and from 900 ℃ to 920 ℃, the apparent reaction order of Yangquan high-ash coal with respect to the unreacted carbon fraction approximates to 2/3 and 1/3 for the non-catalyst case, respectively. Also, the different values of apparent reaction order in the two temperature ranges are presented for the case with 3 % solid alkali catalyst load- ed. At the low temperature ranging from 830 ℃ to 860 ℃, the apparent reaction order of catalytic gasification is 1 since enough active carbon sites on the coal surface are formed during the catalytic gasification by solid alkali. But at the high temperature ranging from 860 ℃ to 920 ℃, the sodium carbonate produced by the reaction of solid alkali with carbon dioxide can be easily fused, transferred and re-distributed, which affects the gasification reaction rate, and the apparent reaction order of catalytic gasification is reduced to 1/3.