LPG is short for Liquefied Petroleum Gas, is a gas produced during the refining of crude oil, or volatilized from oil or natural gas extraction. The main components of liquefied petroleum gas are propane and butane, and may contain a small amount of hydrocarbons composed of propylene and butene. In practical applications, liquefied petroleum gas exists in two forms: one is pure gas, that is, the gas contains (basically) only a single component of propane or butane; the other is mixed gas, that is, propane and butane are used as Mainly mixed with a small amount of olefin in the form of a mixture. It is worth mentioning that LPG is mainly in the form of pure gas internationally.
There are four sources to get LPG:
1) Production from oil and gas field exploitation. The hydrocarbon gas carried in the crude oil or other hydrocarbons carried in the natural gas when the oil field is exploited is initially separated and processed, and then sent to the gas separation plant for processing, and finally propane is obtained separately. and butane. The propane and butane are liquefied under a certain pressure or frozen to a certain temperature, and then packed in different storage tanks. Manufacturers can sell propane and butane separately, or they can mix propane and butane in a certain proportion into LPG that meets quality standards for sale.
2) By-products in the petroleum refining process. Usually crude oil will generate hydrocarbon gas during the processing of atmospheric and vacuum distillation, thermal cracking, catalytic cracking, catalytic reforming, hydrocracking and delayed coking and other process units. After these gases are absorbed and stabilized, under a certain pressure Dry gas and rich gas are separated. The main components of dry gas are methane and non-hydrocarbon gases, as well as a small amount of ethane and ethylene. Usually, this kind of gas is directly sent to the gas tank for concentration, and then distributed to the heating furnace of the refinery as fuel; the main components of the rich gas are propane, propylene, butane, butene, and a small amount of pentane, pentane and pentane. Olefins and non-hydrocarbon compounds, such gases become LPG mainly composed of propane, propylene, butane and butene under certain pressure. It is worth mentioning that the LPG produced by refineries in my country is mainly obtained from catalytic cracking units.
3) Produced from refinery ethylene units. In the process of cracking light oil or light hydrocarbons to produce ethylene, LPG components will also be produced; such LPGs are of poor quality and generally contain high carbon four components. If the refinery and the ethylene plant belong to the same unit, the LPG from the two different sources can usually be properly blended in order to obtain the LPG that meets the national standard.
4) LPG deep processing exhaust. At present, for the carbon four components in LPG, after the deep processing device, some unused components also constitute an important source of LPG. At present, the deep processing of C4 mainly includes the main large-scale mass production process routes such as alkylation unit, isomerization unit, aromatization unit, methyl ethyl ketone unit, and sec-butyl acetate unit. Among them, the alkylation unit uses n-butene and isobutane in the carbon four components, and about 20% of the LPG tail gas is by-product; the isomerization unit mainly uses the n-butene component, and about 20% of the LPG tail gas is by-product; Aromatization utilizes the n-butene component, and about 60% of the LPG tail gas is produced as a by-product.
