In the petroleum refining process, the exhaust gas components mainly include six major categories: sulfides, alkanes, olefins, halogenated hydrocarbons, benzene series, and oxygen-containing organic substances. Quantitative test results show that the overall level of odor contaminant concentration in the main processing unit from high to low ranks as follows: gas separation processing device> sewage tank processing device> gasoline and diesel processing device.

The major pollutants of the main processing units of a petroleum refinery are as follows: gas pollutants in gas separation processing device include acetone, 2-butene, butane, ethanethiol, dimethyl sulfide, and methyl mercaptan. Gas pollutants in the gas and diesel processing device include acetone, propylene, isobutane, n-pentane and p-diethylbenzene; and gas pollutants in the sewage tank processing device include 1-butene, 2-butene, 1-pentene, acetone, propylene and ethanethiol.