我国发展煤制天然气误区分析

从煤炭中的C转化成CH4,需要进行煤气化、脱硫、CO变换、脱除CO2,然后甲烷化反应。在这一生产过程中,碳的利用率和热能转换率均约为1/3,制取1000m3的CH4要放出约3.34t的二氧化碳。按照我国拟建和在建的煤制天然气规模360×108m3/a、碳的利用率1/3计,将浪费煤炭5664×104t标煤,排放二氧化碳1.2×108t,总投资需2100亿元。据测算,煤制天然气生产成本约为3元/m3CH4,与管输进口天然气相比,价格上没有竞争性,并带来环境污染。由于煤制天然气投资费用高(1000m3/a天然气的投资费用约合5833元)、碳与热能利用率低、污染源处理费用高,所以煤制天然气不应该是煤清洁利用的发展方向。我国常规天然气储量和产量迅速增加,预计到2020年天然气产量将达到2000×108m3(约合2×108t油当量),而有关机构预测我国2020年天然气消费量为1.46×108t油当量,国产常规天然气产量就可满足国内燃料消费需求,为此我国完全没有必要大规模建煤制天然气项目。

Analysis of Misunderstandings in Developing Coal Gasification in China

To convert C in coal to CH4,some procedures are necessary including coal gasification,desulfurization,CO conversion,CO2 removal and methanation reaction.During the whole process,both the utilization rate and heat conversion rate of carbon are about 1/3 and producing 1000m3 of CH4 will discharge about 3.34t of carbon dioxide.If calculations are based on the coal gasification capacity of 360×108m3/a planned and under construction in China and a carbon utilization rate of 1/3,5664×104t of coal equivalent of coal would be wasted and carbon dioxide emissions would reach 1.2×108t.Investment required would total 210 billion yuan.On rough calculations,the cost of gasifying coal is about 3 yuan per m3 of CH4.The price of such gas would not be competitive as compared to imported natural gas by pipeline and these projects would cause environmental pollution.As coal gasification projects require high investment（about 5833 yuan needed for 1000m3/a coal gasification capacity）,the utilization rates of carbon and heat are low and the costs of treating polluting sources are high,coal gasification should not be the direction of clean coal utilization.China′s reserves and production of conventional natural gas are growing rapidly.The country′s natural gas production is expected to reach 2000×108m3（about 2×108t of oil equivalent） by 2020 and some institutions have predicted that China′s natural gas consumption will stand at 1.46×108t of oil equivalent in 2020.Therefore,domestic production of conventional natural gas would be capable of meeting domestic fuel demand.For this reason,there is no need for China to build coal gasification capacity on a large scale.