tanks had not been upgraded to retain reformulated gasoline. As a consequence,
tanks were leaking gasoline that contained MTBE into the ground and drinking
water systems. In the USA, ethanol is the primary oxygenate used for blending.
Diesel Fuel
The policies in place to control emissions from motive fuels have moved from
gasoline engines to diesel engines. Similar to the gasoline fuels, diesel has also
changed in composition to meet these environmental constraints while still
maintaining a required performance standard. These changes have imposed a
major impact on the refining industry at a time when the demand for diesel is
increasing. Again, as in the case of the gasoline fuel, reformulated diesel fuel
becomes part of the modern diesel specification and composition. These are
described and discussed in the following sections.
The Diesel Engine
Before dealing with the diesel fuel, it may be advantageous to review briefly the
principles of the diesel engine itself: diesel engines have historically been preferred
in many applications because of their simplicity of design, power, durability, and
higher fuel efficiency. Diesel engines fit into three categories and these are:
• Low-speed engines
• Medium-speed engines
• High-speed engines
Low-speed engines. These operate at less than 300 revolutions per min (rpm) and
are used for applications that require sustained heavy loads at constant engine
speed. Examples are the main propulsion engines in marine vessels and engines
used in electric power generation.
Medium-speed engines. These operate at speeds between 300 and 1,000 rpm and
are used for applications with fairly high loads and relatively constant speeds.
Engines used in auxiliary power plants on marine vessels and in smaller power
generation plants are examples of this type of diesel engine.
High-speed engines. Operate at speeds above 1,000 rpm and are designed for
frequent and wide variations in load and speed. This is the type of engine used for
road transport and diesel locomotives.
Almost all diesel engines use a standard four-stroke design which are intake,
compression, power, and exhaust. During the intake stroke, air alone enters the
cylinder, and during the compression stroke, the air is compressed by the upward
movement of the piston. The final temperature and pressure reached in the cylinder
is a function of the compression ratio, engine speed, and engine design. Pressures of
450 psig and temperatures of 500
F are typical. Shortly before the end of the
compression stroke, one or more jets of fuel are injected into the cylinder. The fuel
pump introducing these jets is usually cam-driven type and operates at pressures
76
D.S.J. Jones and S.A. Treese
tanks were leaking gasoline that contained MTBE into the ground and drinking
water systems. In the USA, ethanol is the primary oxygenate used for blending.
Diesel Fuel
The policies in place to control emissions from motive fuels have moved from
gasoline engines to diesel engines. Similar to the gasoline fuels, diesel has also
changed in composition to meet these environmental constraints while still
maintaining a required performance standard. These changes have imposed a
major impact on the refining industry at a time when the demand for diesel is
increasing. Again, as in the case of the gasoline fuel, reformulated diesel fuel
becomes part of the modern diesel specification and composition. These are
described and discussed in the following sections.
The Diesel Engine
Before dealing with the diesel fuel, it may be advantageous to review briefly the
principles of the diesel engine itself: diesel engines have historically been preferred
in many applications because of their simplicity of design, power, durability, and
higher fuel efficiency. Diesel engines fit into three categories and these are:
• Low-speed engines
• Medium-speed engines
• High-speed engines
Low-speed engines. These operate at less than 300 revolutions per min (rpm) and
are used for applications that require sustained heavy loads at constant engine
speed. Examples are the main propulsion engines in marine vessels and engines
used in electric power generation.
Medium-speed engines. These operate at speeds between 300 and 1,000 rpm and
are used for applications with fairly high loads and relatively constant speeds.
Engines used in auxiliary power plants on marine vessels and in smaller power
generation plants are examples of this type of diesel engine.
High-speed engines. Operate at speeds above 1,000 rpm and are designed for
frequent and wide variations in load and speed. This is the type of engine used for
road transport and diesel locomotives.
Almost all diesel engines use a standard four-stroke design which are intake,
compression, power, and exhaust. During the intake stroke, air alone enters the
cylinder, and during the compression stroke, the air is compressed by the upward
movement of the piston. The final temperature and pressure reached in the cylinder
is a function of the compression ratio, engine speed, and engine design. Pressures of
450 psig and temperatures of 500
F are typical. Shortly before the end of the
compression stroke, one or more jets of fuel are injected into the cylinder. The fuel
pump introducing these jets is usually cam-driven type and operates at pressures
76
D.S.J. Jones and S.A. Treese