As an investor in LPG, it is necessary to know how LPG "came" and "didn't come". In the global liquefied gas supply, 10% is associated gas from oil fields, 52% is from non-associated gas fields, and 38% is from petroleum refining. The supply of LPG in China is mainly divided into two parts: imported gas and domestic gas. Imported gas is purchased through the coastal liquefied petroleum gas import terminal, and most of it is imported through the freezing ship in the form of pure propane and pure butane, stored in the freezing tank, and sold as fuel after mixing. Domestic gas is a by-product of oil refining process. Because of its complex composition, it needs to be stored in a pressure vessel.
In addition, part of the tail gas after deep processing of LPG is also used as the supply source of LPG. The composition of household liquefied petroleum gas is relatively complex and varies greatly. 1. Hydrocarbon gases carried in crude oil during oil field exploitation or other hydrocarbon gases carried in natural gas during gas field exploitation are sent to gas separation unit for treatment after preliminary separation, and finally propane and butane are obtained respectively. Propane and butane are liquefied or frozen to a certain temperature under a certain pressure and packed in different storage tanks.
2. The liquefied petroleum gas produced by the refinery is a by-product of the petroleum refining process, which will be produced in the processing of various process devices, such as atmospheric and vacuum distillation, thermal cracking, catalytic cracking, catalytic reforming, hydrocracking and delayed coking. After these gases are absorbed and stabilized, dry gas and rich gas are separated under a certain pressure. Generally speaking, this gas will be sent directly to the gas holder for concentration, and then distributed to the heating furnace of the refinery as fuel. The liquefied petroleum gas produced by China Refinery mainly comes from catalytic cracking unit.
3. LPG components will also be produced in the cracking process of light oil or light hydrocarbon in ethylene plant of refinery. This kind of liquefied petroleum gas is of poor quality and usually contains high C4 content. If the refinery and ethylene plant belong to the same plant, it is usually possible to properly mix these two different sources of liquefied petroleum gas to obtain liquefied petroleum gas that meets the national standards.
4. After the C4 component in LPG tail gas produced by deep processing of LPG passes through the deep processing device, some unused components also constitute an important source of LPG. At present, the deep processing of C4 mainly includes alkylation unit, isomerization unit, aromatization unit, methyl ethyl ketone unit and sec-butyl acetate unit.