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Liquefied Petroleum Gas
In crude oil refining, the gases that make up LPG are the first products
produced on the way to making the heavier fuels such as diesel, jet fuel,
fuel oil, and gasoline. Roughly 3% of a typical barrel of crude oil is refined
into LPG although as much as 40% of a barrel could be converted into LPG.
Although tied to the production of natural gas and crude oil, LPG has its
own distinct advantages and can perform nearly every fuel function of the
primary fuels from which it is derived.
7.3 Properties of LPG
While LPG is stored as a liquefied gas under pressure at ambient temperature, it is usually used in the liquid form for internal combustion engines,
being directly injected into the engine by the fuel injection system. The term
“LPG” covers a range of mixtures of propane and butane stored as liquids
under pressure, but it is propane that is mostly used to fuel vehicles.
An LPG-derived refinery can differ from its refinery counterpart. However,
whether refinery or natural gas origin, a mixture of liquefied saturated and
unsaturated hydrocarbons in the range of C3–C4 is considered boiling.
Commercially, LPG is sold to domestic and industrial customers in four
grades.
• LPG propane consisting mainly of propane and/or propylene
• LPG butane consisting mainly of n-butane, isobutene, and/or
butylenes
• LPG mixture consisting of C3 and C4 hydrocarbons
• High purity propane containing about 95% propane
Table 7.1 also shows the composition of LPG for different countries as butane
is mixed with propane at ratios varying from 0% (pure propane used) to 75%.
Moreover, LPG contains traces of hydrocarbon impurities such as ethane, ethylene, hexanes, pentanes, and methyl acetylene; sulfur compounds such as
hydrogen sulfide, mercaptanes and elemental sulfur and traces of ammonia,
nitrogen, and sodium. These sulfur compounds and particularly elemental
sulfur in LPG are corrosive toward copper and other metals. Though the
present gas compressors and liquid transfer pumps are the nonlubricated
type, some compressors used in the system are lubricating oil pumps and
there is a chance of leakage of lubricating oil into the LPG. Water is present
in LPG naturally when it is produced from natural gas, whereas in refinery LPG, caustic washing generates water. If LPG is to be stored under lowtemperature conditions, LPG has to pass through a bed of alumina before
it is stored. The correct amount of water dissolved in LPG depends on its
Liquefied Petroleum Gas
In crude oil refining, the gases that make up LPG are the first products
produced on the way to making the heavier fuels such as diesel, jet fuel,
fuel oil, and gasoline. Roughly 3% of a typical barrel of crude oil is refined
into LPG although as much as 40% of a barrel could be converted into LPG.
Although tied to the production of natural gas and crude oil, LPG has its
own distinct advantages and can perform nearly every fuel function of the
primary fuels from which it is derived.
7.3 Properties of LPG
While LPG is stored as a liquefied gas under pressure at ambient temperature, it is usually used in the liquid form for internal combustion engines,
being directly injected into the engine by the fuel injection system. The term
“LPG” covers a range of mixtures of propane and butane stored as liquids
under pressure, but it is propane that is mostly used to fuel vehicles.
An LPG-derived refinery can differ from its refinery counterpart. However,
whether refinery or natural gas origin, a mixture of liquefied saturated and
unsaturated hydrocarbons in the range of C3–C4 is considered boiling.
Commercially, LPG is sold to domestic and industrial customers in four
grades.
• LPG propane consisting mainly of propane and/or propylene
• LPG butane consisting mainly of n-butane, isobutene, and/or
butylenes
• LPG mixture consisting of C3 and C4 hydrocarbons
• High purity propane containing about 95% propane
Table 7.1 also shows the composition of LPG for different countries as butane
is mixed with propane at ratios varying from 0% (pure propane used) to 75%.
Moreover, LPG contains traces of hydrocarbon impurities such as ethane, ethylene, hexanes, pentanes, and methyl acetylene; sulfur compounds such as
hydrogen sulfide, mercaptanes and elemental sulfur and traces of ammonia,
nitrogen, and sodium. These sulfur compounds and particularly elemental
sulfur in LPG are corrosive toward copper and other metals. Though the
present gas compressors and liquid transfer pumps are the nonlubricated
type, some compressors used in the system are lubricating oil pumps and
there is a chance of leakage of lubricating oil into the LPG. Water is present
in LPG naturally when it is produced from natural gas, whereas in refinery LPG, caustic washing generates water. If LPG is to be stored under lowtemperature conditions, LPG has to pass through a bed of alumina before
it is stored. The correct amount of water dissolved in LPG depends on its