204
Alternative Fuels for Transportation
the possibility to obtain the same power output from the engine fueled with
diesel oil and LPG. Also, the high octane number allows compressing of the
propane–butane with air in CI engines with low-compression ratio without
apprehension of self-ignition appearance and enables nonknocking combustion of the mixture. This is in addition to improved exhaust gas composition
and lower cost per energy unit from LPG in comparison with diesel oil.
Literature analysis shows the fueling of IC engines with lean homogeneous mixtures is more and more common. There are systems with spark
ignition (SI) of the mixture and systems where the mixture is ignited by pilot
diesel oil dose. The first solution seems to be more advantageous because
one fuel is used for fueling the engine. But the ignition of lean mixture by
spark is more difficult, so such systems require special solutions of ignition.
This problem disappears in CI engines. Of course, application of two fuels
simultaneously is necessary.
7.2 LPG Production
LPG is formed naturally, interspersed with deposits of petroleum and natural gas. Natural gas contains LPG, water vapor, and other impurities that
must be removed before it can be transported in pipelines as a salable product. LPG can be produced from natural gas purification or from crude oil
refining. It consists of hydrocarbons that are vapors, rather than liquids, at
normal temperatures and pressures, but that turn to liquid at moderate pressures; its main constituent is propane, and it is sometimes referred to by that
name.
7.2.1 Natural gas and Oil extraction
When natural gas and crude oil are drawn from the earth, a mixture of
several different gases and liquids are in fact extracted, with LPG typically
accounting for roughly 5% of the whole. Before natural gas and oil can be
transported or used, the gases that make up LPG, which are slightly heavier
than methane, are separated out.
7.2.2 Crude Oil refining
The process of refining oil is complex and involves many stages. LPG is produced from oil at several of these stages including atmospheric distillation,
reforming, cracking, and others. It is produced because the gases of which it
is composed (butane and propane) are trapped inside the crude oil. In order
to stabilize the crude oil before pipeline or tanker distribution, these “associated” or natural gases are further processed into LPG.
Alternative Fuels for Transportation
the possibility to obtain the same power output from the engine fueled with
diesel oil and LPG. Also, the high octane number allows compressing of the
propane–butane with air in CI engines with low-compression ratio without
apprehension of self-ignition appearance and enables nonknocking combustion of the mixture. This is in addition to improved exhaust gas composition
and lower cost per energy unit from LPG in comparison with diesel oil.
Literature analysis shows the fueling of IC engines with lean homogeneous mixtures is more and more common. There are systems with spark
ignition (SI) of the mixture and systems where the mixture is ignited by pilot
diesel oil dose. The first solution seems to be more advantageous because
one fuel is used for fueling the engine. But the ignition of lean mixture by
spark is more difficult, so such systems require special solutions of ignition.
This problem disappears in CI engines. Of course, application of two fuels
simultaneously is necessary.
7.2 LPG Production
LPG is formed naturally, interspersed with deposits of petroleum and natural gas. Natural gas contains LPG, water vapor, and other impurities that
must be removed before it can be transported in pipelines as a salable product. LPG can be produced from natural gas purification or from crude oil
refining. It consists of hydrocarbons that are vapors, rather than liquids, at
normal temperatures and pressures, but that turn to liquid at moderate pressures; its main constituent is propane, and it is sometimes referred to by that
name.
7.2.1 Natural gas and Oil extraction
When natural gas and crude oil are drawn from the earth, a mixture of
several different gases and liquids are in fact extracted, with LPG typically
accounting for roughly 5% of the whole. Before natural gas and oil can be
transported or used, the gases that make up LPG, which are slightly heavier
than methane, are separated out.
7.2.2 Crude Oil refining
The process of refining oil is complex and involves many stages. LPG is produced from oil at several of these stages including atmospheric distillation,
reforming, cracking, and others. It is produced because the gases of which it
is composed (butane and propane) are trapped inside the crude oil. In order
to stabilize the crude oil before pipeline or tanker distribution, these “associated” or natural gases are further processed into LPG.