基于含碳废弃物与煤共气化的碳循环概念及碳减排潜力分析

Concept of carbon cycle based on co-gasification of carbon containing waste and coal and analysis of carbon emission reduction potential

我国是世界上最大的煤炭生产和消耗国,煤炭的开发利用导致了大量CO_(2)排放,为助力煤炭的清洁转化利用,基于含碳废弃物与煤共气化的碳循环概念及碳减排潜力进行分析。计算了燃煤发电过程和以煤气化为核心的煤制甲醇生产过程CO_(2)的排放,煤气化过程基于含碳废弃物与煤共气化提出了碳循环概念,利用气化炉协同处理各类含碳废弃物,实现跨系统的碳循环利用及原煤使用量下降,是一项非常有潜力的碳减排技术。以百万吨级的煤直接液化项目为例,实施了碳循环后,液化油渣中50%的碳被固定在沥青产品中,减少CO_(2)排放量约58万t;以油渣萃余物替代约10%的煤制氢的气化原料煤,CO_(2)减排量约30万t;避免油渣萃余物直接燃烧产生的CO_(2)排放量约35万t,即每年可以实现CO_(2)减排量达123万t。若基于含碳废弃物与煤共气化的碳循环概念得以推广,2019年我国煤化工行业可节约原煤用量2 391万t,碳减排潜力约3 710万t。

China has the largest coal production and consumption in the world. A large amount of CO_(2)is discharged due to the development and utilization of coal. In order to help realize the clean transformation and utilization of coal, the CO_(2)emissions of coal-fired power generation and coal gasification to methanol process was analyzed. The CO_(2)emissions from coal-fired power generation process and coal to methanol production process with coal gasification as the core were calculated. Through the analysis and calculation, in the coal gasification to methanol process, about 37% of carbon from the raw coal enters the product, which can achieve a certain proportion of "chemical carbon fixation". The CO_(2)concentration in the syngas produced in the coal gasification process is high. Coal gasification to methanol process is easier to achieve large-scale and low-cost carbon capture and storage than coal-fired power generation. Based on the co-gasification of carbon containing waste and coal, the concept of carbon cycle is put forward. It is a very potential carbon emission reduction technology to use gasifiers to deal with all kinds of carbon containing waste in a coordinated manner, so as to realize cross system carbon recycling and save the use of raw coal. Take 1 million t/a coal direct liquefaction project for example, the reduction of CO_(2)emission is about 1.23 million tons every year by the gasification of carbonaceous wastes. CO_(2)emission reduction consists of three parts. Part I is about 0.58 million tons, due to about 50% of carbon from the coal liquefaction residues are entered the asphalt product. Part II is about 0.30 million tons, due to 10% raw coal for hydrogen production is placed by coal direct liquefaction residues raffinate. Part III is about 0.35 million tons by avoiding the direct combustion of coal direct liquefaction residues raffinate. If this method extends to the coal chemical industry, it can save about 23.91 million tons of raw coal in China and reduce 37.10 million tons CO_(2)emission potentially in 2019.