Process design and analysis of coal-based methanol to aromatics integrated with light hydrocarbons conversion

Methanol to aromatics is gradually becoming mature with years of research and development, which provides possibility for industrialization of coal to aromatics. However, methanol aromatization results in a quite low aromatics yield of about 40 % on the dry basis. In addition to aromatics, considerable light hydrocarbons are produced in methanol aromatization. Focusing on these light hydrocarbons, this paper proposes a novel process design that integrates coal to aromatics with steam reforming of light hydrocarbons in order to increase the yield of aromatics. First, a simulation model for producing aromatics from coal via methanol is developed and the mass and energy balances are obtained through rigorous simulation. Next, light hydrocarbon byproducts are considered to produce hydrogen-rich syngas via steam reforming, which is used as raw material to the methanol synthesis unit with syngas from coal gasification. Based on this idea, a novel process design where coal to aromatics is integrated with light hydrocarbons conversion is proposed. Such a novel design not only reduces the load of the water gas shift unit, but also simplifies the product separation unit. Based on rigorous simulation, the two processes are analysed in terms of mass balance, energy consumption, and economy. The results show that the aromatics yield of the integrated process increases by 146 %, the mass flow of products increases by 3.9 %, while CO2 emission of the acid gas removal unit decreases by 12 %. Besides, the integrated process results in 87 % higher net present value than that of the non-integrated process.