O_2/CO_2煤炭地下气化模型试验

O_2/CO_2 underground coal gasification model test

利用O2/CO2作为气化剂进行煤炭地下气化,不仅能够提高煤气中有效组分的含量和CO/H2比例,而且煤气脱碳后适合用于合成甲醇或液化天然气（LNG）.为考察O2/CO2地下气化的可行性,通过模型试验在模拟煤层中进行不同O2/CO2比的气化试验,考察不同CO2浓度气化下的煤气组分特征、温度场分布、燃空区立体形状以及污染物析出情况.试验表明：CO2体积分数为40％～50％时,煤气中的CO和H2的含量均在25％左右,CO2的含量小于50％.与已有的富氧空气地下气化模型试验结果相比,在气化剂中的CO2能够抑制地下气化过程中CO2的生成,O2/CO2气化下的温度场相对较低,气化过程中煤层的最高温度也只有1 200℃,对煤气有效组分的生成比较有利.最终的燃空区3D形状符合一般燃烧扩展规律,试验过程中还监测了硫化氢、氨气和焦油等污染物的析出量.

Abstract：This paper investigated the O2/CO2 gasification technique used to gasify coal in the underground coal gasification model test. The O2/CO2 as gasifying agent for underground gasification can not only improve the content of effective components and the CO/H2 ratio in coal gas, but also make the coal gas after deearbonization more suitable for synthesis of methanol or liquefied natural gas （LNG）. In order to explore the feasibility of O2/CO2 underground gasification,the O2/CO2 gasification test with different carbon dioxide concentration were carried out in a simulated coal seam, the gas composition, temperature field, the 3 D shape of combustion zone, and contaminants release under differ- ent gasification conditions were studied. The results show that when the carbon dioxide concentration in the gasification agent ranges from 40% to 50% ,in the product gas, the concentration of CO or H2 is approximately 25%, the CO2 is less than 50%. Compared with the results of oxygen-enriched air underground coal gasification carried out, the O2/CO2 gasification process can inhibit the generation of CO2 during gasification process, the temperature of gasification zone is relatively low, the maximum temperature is only 1 200℃, which is beneficial for producing coal gas. The final 3 D cavity shape complies with the general combustion propagation law. Also, the amount of precipitation of hydrogen sulfide, ammonia, tar and other pollutants were monitored during the test. Key words： O2/CO2 ; underground coal gasification ; model test; CO2 concentration ; temperature field