Study on emissions of volatile organic compounds from a typical coking chemical plant in China

Coking chemical industry associated with high energy consumption and high pollution emits significant amount of volatile organic compounds (VOCs) to atmosphere, but is often ignored. This article reports a new study on emissions of VOCs from a typical coking chemical plant. Results show that about 70 species of VOCs including alkanes, alkenes, alkynes, aromatic hydrocarbons, halogenated hydrocarbons and oxygenates are detected, naphthalene and benzene could be used as the emission markers. Compared to coking stage, gas purifying stage is found to have 4 times more total concentrations of VOCs, in which condensing and blasting process is found to be the largest contributor with 77% ozone formation potential (OFP) contribution. Emission control measures currently used are insufficient and inefficient to reduce VOCs to meet regulatory emission standards. Further, by using a proposed integrated emission factor of 2.652 g/kg coke, the coking chemical industry in China was estimated to account for about 7.8-20% of total historical industrial VOCs emissions, and about 1241 Gg of VOCs were emitted in 2019. A large proportion is emitted from the northern China with a distinctive spatial distribution. Shanxi, Hebei, Shandong, and Shannxi provinces are the top four emitters. It is suggested that more stringent and efficient measures should be taken on the coking chemical industry, not just on the coking processes, but also on the gas purifying processes.