褐煤热解-气化-制油系统的CO_2减排策略

Strategies of lignite pyrolysis-gasification-oil system for CO_2 emission reduction

褐煤热解-气化-制油系统是现代煤化工发展的一个重要研究内容。来自系统多个单元产生的CH4和CO2如果发生重整反应,将重整得到H2/CO比值较高的合成气添加到制油流程中,可实现更多的C被固定到产品中而减少CO2的直接排放量。对CH4-CO2和CH4-H2O两种重整反应方式、来自煤热解和费托合成两股甲烷气和典型的干粉气化和水煤浆气化两种流程进行了组合研究。分析结果显示,来自热解和费托合成的甲烷重整后不足以提供调节合成气H2/CO比例所需的氢气,水煤气变换反应对于褐煤制油系统来说是必需的。从C转化成油的角度来看,采用干粉气化和CH4-H2O重整的方案是较好的选择。

CO2 emission reduction is an important aspect of advanced coal chemical engineering. The CH4-CO2 reforming is one of the important choices for CO2 cycling, while the CH4-H2O reforming is able to reduce the CO2 emission from the H2 production or the adjustment of the H/C ratio of syngas. The feedstock methane can be obtained from several units of the lignite-pyrolysis-gasification-oil system. Through CH4reforming, high ratio of H2/CO syngas can be obtained and applied into the oil production system, more carbon would be fixed into the product and less CO2 is thus emitted. Two reforming reactions, two methane sources and two types of gasifier, namely typical dry powder entrained-flow gasifier and coal-water slurry entrained-flow gasifier, were investigated in this work. Results showed that methane from pyrolysis and Fischer-Tropsch synthesis is deficient in adjusting H2/CO ratio in the syngas, and the water gas shift reaction is necessary for lignite to oil system. In terms of carbon conversion to oil, the dry powder gasification-CH4-H2O reforming is the better choice.