Liquefied petroleum gases (LPG) are produced from associated petroleum gas. These are pure gases or special mixtures that can be used to heat buildings, to produce petrochemicals and as a motor fuel.
NGL in GFU
Liquefied gases are made from natural gas liquids (NGL), which are in turn recovered from associated petroleum gas (APG).
NGLs are separated into components – individual hydrocarbons – in gas fractionation units (GFU). The separation process is similar to that of APG. However, in this case separation must be conducted more accurately. Various products can be made from NGL during the gas fractionation process. These might be propane, butane or a propane-butane mixture (it is called TPBM, or technical propane-butane mixture). TPBM is the most common type of liquefied gases. This is a particular form, in which the product is supplied to people, industrial plants, and for export. Thus, 42 per cent of 1.762 million tons of LPG sold by Gazprom Gazenergoset in 2010 fell on the propane-butane mixture, one-third of supplies fell on butane, and about 14 per cent – on propane.
Technical propane, technical butane, motor fuel propane (MFP) and a motor fuel propane-butane (MFPB) mixture are produced in the same way by NGL fractionation.
There are also other components extracted by NGL processing. These are isobutene, isobutylene, pentane and isopentane.
How are liquefied gases used?
Liquefied petroleum gases can be used in a number of ways. Probably, everyone knows bright red cylinders signed “propane” since the Soviet times. They are used for cooking on stove plates or for heating country houses.
Liquefied petroleum gas can also be used in lighters: these are usually filled with either propane or butane.
Liquefied gases are used to heat industrial plants and residential buildings in the regions with no pipeline gas. In this case, LPG is stored in gasholders, which are special tanks that can be installed above or under ground.
Propane-butane is second best after natural gas delivered via trunklines in terms of efficiency. Besides, the use of LPG is more eco-friendly as compared to diesel fuel or fuel oil.
Gas into motors and for bags
Liquefied gases are used as an alternative motor fuel.
Natural gas vehicles are up-to-date as the domestic vehicle fleet of over 34 million units annually emits 14 million tons of pollutants with exhaust gases into the ambient air. This is 40 per cent of all industrial air emissions. Exhaust gases of liquefied gas fired motor vehicles are several times less harmful.
Exhaust gases of motors vehicles contain 2 to 3 times less carbon oxide (CO) and 1.2 times less nitrogen oxide. At the same time, the cost of LPG is about 30 to 50 per cent that of petrol.
The NGV fuel market is growing fast. To date, there are over 3,000 gas filling stations and more than 1 million NGVs in Russia.
Finally, liquefied petroleum gases are a feedstock for the petrochemical industry. LPGs undergo a very complex process called pyrolysis, taking place at very high temperatures. The resulting products are called olefins – ethylene and propylene. These are subsequently polymerized and transformed into polymers or plastic, such as polyethylene, polypropylene, or other products. Thus, the polyethylene bags, disposable dishware, food packing and wrapping materials we use in everyday life are produced from liquefied gases.