Conceptual Design Of Coke-oven Gas Assisted Coal Gasification To Methanol Process

Methanol is one of the most important products in chemical industry. Among the manysources of methanol syngas, coal gasification gas, coke-oven gas and natural gas are of greatvalue. China is abundant in coal, less in oil and lean in gas, so the development of natural gasto methanol is is limited. Coal gasification gas is the main source of methanol feed gas.The ratio between hydrogen and carbon monoxide (H/C) of coal gasification gas rangesfrom0.2to1.0because of carbon-rich coal. In order to get the perfect performance ofmethanol synthesis, the suitable ratio should be around2.0, which makes it necessary forwater gas shift (WGS) unit to adjust the ratio in coal to methanol process. WGS needs energyinput, and produces a large amount of carbon dioxide leading to carbon resource waste.China is a big exporter of coke and there is a great deal of coke-oven gas during cokingprocess. The main components of coke-oven gas are hydrogen and methane,60%and26%respectively, with a H/C ratio6.5.This paper proposed a new process of coal to methanol, in which the coal gasificationgas and coke-oven gas are integrated based on the complementation of hydrogen and carbon.Besides, the tri-reforming reaction of methane (TRM) is implemented so that the methane incoke-oven gas and the carbon dioxide in coal gasification gas are converted to hydrogen andcarbon monoxide.Based on Aspen Plus software, the process units of coal to methanol were modeled andsimulated. Coupled with TRM, the coal gasification to methanol process assisted withcoke-oven gas was built by applying the thought of process system engineering. Then, thispaper analyzed the effect of coal gasification and coking capacity and CO conversion rate onH/C ratio of the product gas and efficiency of the whole process.For construction of old factories, when the capacity of coking factory is6million tonneper year, the gasification factory is2million tonne per year, the carbon utilization efficiencyof the whole process increases from40%to65%, and the carbon dioxide emission decreasedby two-thirds. For planned coking factories or industry zone, when the capacity is14million tonne peryear, the WGS installation can be canceled with less cluttering process and less investment. Inthat case, the emission reduction is highlighted.