煤颗粒对化学热回收二段式煤气化工艺的影响

Effect of coal particle-diameter on chemical heat recovery two-stage coal gasification

基于碳和水蒸气、CO2气化的吸热化学反应原理,开发出回收煤气显热的高效化学热回收二段式煤气化工艺,可有效提高现有气流床气化技术的热效率。文中在实验室规模的热态反应平台上,对二段气化床层内煤颗粒粒径对二段床层内的温度分布、二段气化效率及煤渣层残炭率的分布规律进行了实验。研究优选出二段气化炉内煤颗粒粒径范围为10—15 mm。在此条件下,一段炉出口含体积分数34.87%的CO2经二段气化后,出口合成气中的CO2体积分数降为28.64%;二段出口合成气热值比一段出口增加719 kJ/m3,提高了9.16%。实验结果表明:此二段式气化工艺能有效利用一段炉煤气中的显热,提高气化炉的冷煤气效率,同时减少CO2的排放量,具有良好的环境效益。

Based on the principle of endothermic reactions of carbon with H2O and CO2,the two-stage coal gasification process with highly-efficient chemical heat recovery was exploited to recycle the heat.This process can make up the deficiency of the existing entrained-flow gasification process.On a laboratory-scale hot testing installation of heat reaction,the influence of particle-diameter on reaction efficiency,the temperature profile of the second stage gasifier,and the distribution of carbon residue yield in slag layer were studied.The results show that for the second stage gasification the optimized coal particle diameter is 10-15 mm.Under the optimal operating conditions,and compared with CO2 volume fraction in the first stage gasification section outlet,CO2 volume fraction in second stage gasification section can be reduced from 34.87% to 28.64% and the outlet gas thermal value increases by 719 kJ/m^3,and the yield increases by about 9.16%.The results show that this two-stage gasification process can improve the cold gas efficiency of syngas,while reducing carbon dioxide emissions,and it shows that this two-stage gasification process has good environmental benefits.