Novel multi-functional energy system for cogeneration of coke, methanol and power

A novel polygeneration system was integrated in this paper, which co-generates coke, methanol and power, based on coal gas produced by a gasifier and coke oven gas (COG). In conventional coke-making processes, the COG with high quality is burned directly to provide coking heat. However, in coke-making processes of the new system, we burned Coal with low quality rather than COG. According to the whole system analyses, and the character of Coal gas rich in CO and COG rich in H2, we combined these two kinds of gases to make synthesis gases, eliminated the shift and reforming reaction, and adopted the part-recycle scheme in methanol synthesis unit. The new system integrated the processes of coke-making, chemical production and power generation, along with cascade utilization of thermal energy and material. In this manner, both chemical energy of fuel and thermal energy can be used more effectively. Compared to the conventional systems, the primary energy saving ratio is about 22%. The exergy analyses showed that: the coal is transformed into the COG indirectly only by being burnt, through supplying the coking heat by coal instead of COG; the elimination of reforming reaction and the combination of coal gas and COG is the key processes for the high performance of the new system, too. In a word, this new system will provide a new way to utilize coal and COG more efficiently, and a new choice for the clean coal technology.