焦炉煤气-甲醇产业链延伸技术方案的经济分析

摘要

与煤制甲醇和天然气制甲醇工艺相比，焦炉煤气制甲醇不仅可以有效利用焦炉煤气中的氢，而且具有低成本的优势。在焦炉煤气制甲醇工艺基础上，文中提出了3种具有发展潜力的焦炉煤气综合利用方案：①气化煤气-焦炉煤气制甲醇生产方案；②焦炉煤气-乙炔-甲醇下游产品方案；③气化煤气-焦炉煤气-乙炔-甲醇下游产品方案。以200×104 t焦炭的生产规模分析了3种方案经济性，其毛利润分别为24.21亿元，18.92亿元和28.74亿元；内部收益率分别为28.29%、24.34%和27.11%。气化煤气-焦炉煤气-乙炔-甲醇下游产品方案充分发挥了规模效应和产品高附加值的特点，具有明显的经济优势；系统灵活性高，抵御市场风险能力强。%Production cost of methanol from abundant and cheap coke oven gas (COG) is about 800-1000 CNY·t-1 lower than that from coal or natural gas. With expansion of international methanol production capacity and production scale, methanol market competition becomes more intense and cost advantage of coke oven gas to methanol is reduced evidently. It is significant to improve technology and extend industrial chains to use coke oven gas and obtain maximal benefits on the basis of coke oven gas to methanol production. One technical solution is combining coke oven gas with coal gasified gas (CGG) to produce methanol. CH4/CO2 reforming technology is used to convert CO2+CH4 into H2+CO, and adjust H2/CO ratio of syngas in this scheme. With this scheme, methanol production can increase by 30%. Another option is to extend methanol industrial chain to obtain high-value-added downstream products, such as vinyl acetate, polyvinyl alcohol, and 1,4-butanediol. In this design, CH4 is separated from COG to make acetylene, which is used to synthesize methanol downstream products by methane partial oxidation technology. However, 0.07 billion m3 H2 surplus and small scale of methanol production are the disadvantage of this design. Concerning scale effect and industrial chain extension simultaneously, to make full use of the unused H2 resource, dual-gas (COG and CGG)-acetylene-methanol system is proposed based on the above scheme. In this solution, an appropriate proportion of the CGG is supplied to mix with surplus H2 to obtain syngas with H2:CO = 2:1, which is used to synthesize methanol. With the scale of 2 million ton coke per year, gross profits of the above three systems are 2.421, 1.892 and 2.874 billion CNY, respectively, and the internal rates of return for these schemes are 28.29%, 24.34%and 27.11%accordingly. The dual-gas-acetylene-methanol system is found to be the highest profitable system. Meanwhile, dual-gas-acetylene-methanol system is highly flexible;methanol and methanol downstream product production, as well as production technology can be adjusted according to market requirement, production capacity and resource distribution.