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 FUMIGATION:
Fumigation
is the process of having the natural gas blended with the combustion
air before entering the engine. This mixing takes place before the
turbo charger or air intake for naturally aspirated engines. Most
major manufacturer’s concept of bi-fuel is to inject the natural
gas into the engine under high pressure, an expensive procedure.
ITG
BI-FUEL:
A
fuel balance is maintained by controlling and reducing the normal
flow of diesel fuel so that it now becomes the pilot ignition source
for the enriched gas/air mixture. Natural gas has higher ignition
temperature (1200 degrees) than diesel fuel (500 degrees).
NO
SPARK PLUGS:
The
basic diesel engine design is not changed. Conversion expenses are
lower by not changing compression, heads, pistons, etc….. In principle
the engine remains to be a diesel engine fuel on mainly natural
gas.
GAS/DIESEL
RATIOS:
The
average substitution of gas to diesel range is 80-50% natural gas
and the diesel is reduced to 20-50% of normal. For example, an engine
burning 100 gallons an hour of diesel fuel might be reduced to 20
gallons per hour.
The
displaced 80 gallons is now natural gas. One gallon of diesel fuel
is approximately 139 standard cubic feet of gas so 80 x 139 yields
11, 120 SCF (11.12 therms) of gas consumed per hour. Natural gas
has an average high heat value of 1000 BTU per SCF. One gallon of
#2 diesel is approximately 139,000
BTU per gallon.
 POWER:
ITG
bi-fuel does not derate an engine. Full power is maintained by providing
the necessary BTU energy to the engine as needed. The combined combustion
of natural gas and pilot ignition diesel fuel provides superior
energy efficiencies when compared to each fuel individually.
TEMPERATURES:
Bi-fuel,
unlike dedicated natural gas engines, does not run hotter. In many
cases engines actually run a few degrees cooler.
SWITCHING
FUELS:
A
bi-fuel engine can switch to full 100% diesel fuel operation as
it runs without loss of power. When natural gas pressure is restored,
the process is reversed back to bi-fuel, uninterrupted.
MAINTENANCE:
Bi-fuel
engines need fewer oil changes, they run quieter, do not wet stack
and generally last longer than straight diesel engines.
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