Method for replacing return coal gas in semi-coke process with desorbed gas hydrogen production and fuel system

The invention provides a method for replacing return coal gas in a semi-coke process with desorbed gas in hydrogen production. The method comprises the following steps: step 1, carrying out pressure reduction treatment on primary byproduct desorbed gas so as to obtain low-pressure desorbed gas; step 2, conveying the low-pressure desorbed gas and air into a carbonization furnace flame path of a semi-coke device; step 3, outputting all coal gas generated by coal pyrolysis or destructive distillation in the carbonization furnace to a purification system for purification treatment; and step 4, sequentially conveying the purified coal gas to a pressure swing adsorption hydrogen production device for treatment so as to obtain the primary byproduct desorbed gas and 99.99% of hydrogen. The invention further provides a fuel system applied to the above-mentioned method. The fuel system comprises the semi-coke device, a hydrogen production system and a fuel treatment device, wherein the fuel treatment device comprises a