Petroleum Refining Gases

gas mixtures consisting primarily of low-molecular hydrocarbons formed at petroleum refining installations and during the thermal and catalytic refining processes of petroleum raw materials.

In contrast to natural gas fuels and petroleum by-product gases, most petroleum refining gases contain significant amounts of unsaturated hydrocarbons and hydrogen. Exceptions are those gases that are liberated during the straight-run distillation of petroleum, as well as catalytic reforming and hydroforming gases that consist of paraffin hydrocarbons (such as methane, ethane, and propane) and small quantities of impurities (such as nitrogen, oxygen, and carbon dioxide). A large quantity of unsaturated hydrocarbons is found in gases formed during the operation of high-temperature processes (for instance, the total unsaturated hydrocarbon content in petroleum refining gases under the rigid conditions of coking operations amounts to 50 percent by weight, and during the catalytic cracking of heavy raw materials it totals 56 percent by weight).

The yield of petroleum refining gases at cracking and pyrolysis installations amounts to 8.5-9.5 percent (for refined oil), including up to 2.5 percent unsaturated hydrocarbons. The hydrogen content in petroleum refining gases ranges from 0.2 percent in thermal cracking gases to 7 percent in reforming gases. The unsaturated hydrocarbons (ethylene, propylene, butylène, butadiene) making up petroleum refining gases constitute the raw materials for the petrochemical industry and for the high-octane components of motor fuels. Petroleum refining gases possess the high combustion heat of 52.3 megajoules per cu m (12,500 kilocalories per cu m) and are used as fuel.