关键词: 焦炉煤气, 气化煤气, 甲醇, 产业链, 经济分析

Abstract: 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.

Key words: coke oven gas, gasification gas, methanol, industrial chain, economic evaluation