10-12-2012, 06:14 PM
The Dual-Fuel Engines
1The Dual-Fuel.docx (Size: 249.76 KB / Downloads: 48)
Engine working principle of dual-fuel (DF) engines
The dual-fuel engine utilizes a “lean-burn” otto combustion process when operating on gas.
Here, the gas is mixed with air before the intake valves during the air intake period.
After the compression phase, the gas/air mixture is ignited by a small amount of liquid pilot fuel (LFO).
After the working phase the exhaust gas valves open and the cylinder is emptied of exhaust gases.
The inlet air valves open when the exhaust gas valves close, and the process starts again.
The dual-fuel engine is also equipped with a backup fuel system.
In the event of a gas supply interruption, the engine transfers from gas to fuel oil operation (LFO, HFO) at any load instantaneously and automatically.
Engine working principle of gas-diesel (GD) engines
The GD engine utilizes the diesel combustion process in all operational modes.
In gas mode, the gas is injected at high pressure after the pilot fuel and is ignited by the flame from the pilot fuel injection.
The amount of pilot fuel is equivalent to approximately 5% of the fuel energy input at full engine load.
The gas-diesel engine can be switched over instantly to liquid fuel mode operation.
The liquid fuel can be light fuel oil, heavy fuel oil or crude oil. In this case, the process is the same as the conventional diesel process.
Dual Fuel Conversions
Dual fuel conversion is a very effective tool how to significantly reduce especially fuel costs with a relatively small investment.
The main principle of conversion is reduction of injecting dose of diesel up to 10% value of original diesel consumption. This amount is called "ignition dose" and missing chemical energy is then provided by mixture of air and gas fuel.