What does "Dual-Fuel" mean?
Dual-Fuel can be defined as the simultaneous combustion of two fuels. In the case of the Dual-Fuel System, natural gas is utilized in conjunction with diesel fuel to operate the engine. After conversion, the engine is able to operate on either 100% diesel fuel, or alternately, on a mixture of diesel fuel and natural gas. At no time is the engine able to operate on natural gas exclusively.
On which fuel does the engine start?
During initial startup, the engine operates on 100% diesel fuel. After certain permissive criteria are satisfied the automatic control system commences dual fuel operation. When idling, the engine operates on 100% diesel.
Does the conversion de-rate the engine power?
No. CNG Techs/APG Dual Fuel does not de-rate an engine. Full power is maintained by providing the necessary BTU energy to the engine as needed. The Dual Fuel System maintains OEM compression ratio values, peak horsepower and efficiency levels of the converted engine to remain at par with 100% diesel operation. In some circumstances, the engine may be de-rated in Dual-Fuel mode due to shortcomings in gas supply composition and / or quality. The combined combustion of natural gas and pilot ignition diesel fuel provides superior energy efficiencies when compared to each fuel individually.
What happens to the engine operation, if gas supply is lost?
It automatically changes over from Dual fuel to Diesel Operation. CNG TECHS/APG Dual 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 Dual Fuel, uninterrupted.
What happens when there is a fault condition that merits gas supply shut off:
The gas supply will be stopped automatically for safety, if any limits are exceeded. The diesel engine will not be stopped when the dual fuel system is shut off. The gas supply to the engine will cut off slowly at each trip signal. This is done to prevent the sudden load drop. The closing time of the gas control valve will be adjusted during commissioning so that governor action is matched with the closing of the gas control valve. It is also understood that if engine trips the gas supply to the engine is also stopped
Does the CNG Techs/APG Conversion change anything on the Engine?
CNG Techs/APG Dual Fuel system does not interfere with the Engine integrity. The conversion technology has been designed to allow for in-field retrofit of diesel engines without the need to change or modify the design of the engine. The conversion hardware is mounted externally on the engine and does not require modification of the engine or alteration of any critical engine parameter.
Is there any possibility of explosion due to the presence of natural gas into the engine?
The pre-ignition temperature for the air after the power stroke, is reported in the process calculations matrix submitted in the proposal, and they are about 600o C at the most. Self-ignition of the Natural Gas takes place at temperatures greater than 1000 o C. At worst when there is leakage it should not ignite for this reason and for the fact that the natural gas is a small fraction of the intake air volume - well below the threshold. In addition, from our experience in hundreds of engines converted to dual fue,l we have not experienced any such thing.
Does CNG Techs/APG Dual Fuel system change the Governor timings/settings?
No, CNG Techs/APG Dual Fuel system does not interfere with the normal governor operation.
Will my engine run hotter on Dual-Fuel?
The Dual-Fuel technology has been designed to maintain OEM specifications of all engine temperatures including engine coolant temperature, oil temperature, exhaust gas temperature and intake air temperature. The Dual-Fuel System replaces diesel fuel normally consumed by the engine with an equivalent quantity of natural gas, relative to the heat value of each fuel. As such, engine air-fuel ratios during Dual-Fuel operation remain largely equivalent to 100% diesel operation, resulting in normal peak exhaust gas temperatures and associated peak engine thermal loads.
What effect will the System have on the durability of my engine?
Generally speaking, operation in Dual-Fuel mode has no negative effects on engine wear rates and durability. As explained above, because engine thermal loads are equivalent to 100% diesel operation, no excess wear of combustion chamber components (pistons, rings, valves, injectors, etc.) occurs. In addition, many users of Dual-Fuel have reported positive benefits relative to engine wear including extended oil change intervals and extended time between overhauls. This is primarily the result of the cleaner burning characteristics of natural gas compared to diesel fuel.
Can the engine be converted back to diesel?
Yes. As there are no changes in the engine compression ratio, cylinder heads, or basic operation as diesel cycle engine and the sophisticated computer controlled dual fuel system is as a bolt on technology, the engine can be converted back to dedicated diesel engine if necessary.
Is there a need for auxiliary power to run dual-fuel system:
No. The dual fuel system does not have an engine power requirement in order to run.
The dual-fuel system requires very little maintenance and thus significantly reducing related costs.
Why is Computational Fluid Dynamics (CFD) necessary to convert an engine to dual fuel:
Without the above – a conversion to dual fuel cannot be performed to meet the safety and performance requirements.