After being cooled in the final gas cooler of the coke oven gas from the ammonium sulfate section, the gas enters the bottom of the benzene scrubber and comes into countercurrent contact with lean oil sprayed down from the top of the tower. The gas overflows from the top of the tower and is delivered to various gas-consuming units. The rich oil, which has absorbed the aromatic hydrocarbons in the gas, is pumped by the rich oil pump to the condenser cooler, oil-to-oil heat exchanger, and tubular furnace for heating before entering the benzene stripping tower. In the stripping tower, the absorbed aromatic hydrocarbons are removed through steam stripping. The lean oil, after being cooled by the oil-to-oil heat exchanger and the first and second-stage lean oil coolers, is pressurized by the lean oil pump and recycled for benzene scrubbing.