FAQ

Answer- 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.

Answer- No. Hallong International CNG/LNG/PNG 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. The combined combustion of natural gas and pilot ignition diesel fuel provides superior energy efficiencies when compared to each fuel individually.

Answer- 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.

Answer- It automatically changes over from Dual fuel to Diesel Operation. Hallong International CNG/LNG/PNG 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.

Answer- 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.

Answer- Hallong International Dual-Fuel Conversion 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.

Answer- The pre-ignition temperature for the air after the power stroke is reported in the process calculations matrix – they are about 600°C at the most. Self-ignition of the Natural Gas takes place at temps greater than 760°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 – Our experience in hundreds of engines converted to dual fuel, we have not experienced any such thing. Moreover, total gas entering into the engine is approximately 2.5% of the total Air Flow into the engine. The scavenging loss is around 15%, so the mixture entering the waste heat recovery combustion chamber will have 0.375% of Natural Gas. The mixture has to be 5% rich with gas to fall in the burning zone. Moreover; the temperature should be around 760°C degrees C to burn the gas.

Answer- No, Hallong International Dual Fuel system does not interfere with the normal governor operation.

Answer- Typical Lub-Oil for diesel/ HFO engines includes an alkaline additive package to compensate the formation of Sulphuric acid in the combustion process. Usage of Natural Gas will reduce the formation of sulphuric acid; hence the additive alkaline package is reformulated in accordance to engine use under dual fuel. We highly recommend that lube Oil analysis be conducted on regular basis to monitor changes- specifically the TBN number. As part of our service we request the clients to send in their lube oil analyses so that we can assist with the reformulation determination. Lube Oil used specifically for dedicated gas engines is not to be taken as the appropriate lube oil to be used in dual fuel applications.

Answer- Because of the very high ignition temperature of natural gas (approximately 760°C), sufficient heat is not generated during the diesel compression stroke to ignite 100% natural gas. As such, dedicated gas engines employ spark plugs and an ignition system to facilitate combustion of the air-natural gas mixture. In contrast, during Dual-Fuel operation, a reduced quantity of diesel fuel acts as the ignition source for the air-gas mixture; this process is often referred to as pilot ignition.

Answer- 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.

Answer- As explained above, the Dual-Fuel System replaces diesel fuel with an equivalent quantity of natural gas. This process results in the same net fuel burn vs. load as would be experienced during 100% diesel operation.

Answer- 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.

Answer- Fuel cost savings resulting from operation in Dual-Fuel mode will vary according to the respective cost of each of the fuels. If there is a significant cost differential between the cost of diesel fuel and the equivalent quantity of natural gas (heat value basis) in favor of the natural gas, significant fuel cost savings would result. The closer the fuels are in price, the lower the fuel cost savings will be during Dual-Fuel mode. In addition to fuel cost saving, engine maintenance savings (as explained above) may also contribute to the economic benefit of Dual-Fuel operation.

Answer- Yes. As there are no changes in the engine compression ratio, cylinder heads, or basic operation as diesel cycle engine and furthermore, the sophisticated PLC-controlled dual fuel system is a cutting-edge technology, where the air-gas mixer charge is port injected, and so can be converted back to dedicated diesel engine as needed.

Answer- The emissions from the engines after dual fuel conversion will be more environmentally friendly. The NOX, SOX and Particulate matter will drop drastically. The component of CO will increase but will remain within the allowed limits. In the event the CO goes up more than normal – a catalytic converter will be used to bring the CO levels to acceptable levels.

Answer- Because of the very high ignition temperature of natural gas (approximately 650 °C), sufficient heat is not generated during the diesel compression stroke to ignite 100% natural gas. As such, dedicated gas engines employ spark plugs and an ignition system to facilitate combustion of the air-natural gas mixture. In contrast, during Dual-Fuel operation, a reduced quantity of diesel fuel acts as the ignition source for the air-gas mixture; this process is often referred to as pilot ignition.

Answer- 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.

Answer- As explained above, the Dual-Fuel System replaces diesel fuel with an equivalent quantity of natural gas. This process results in the same net fuel burn vs. load as would be experienced during 100% diesel operation.

Answer- 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.

Answer- Fuel cost savings resulting from operation in Dual-Fuel mode will vary according to the respective cost of each of the fuels. If there is a significant cost differential between the cost of diesel fuel and the equivalent quantity of natural gas (heat value basis) in favor of the natural gas, significant fuel cost savings would result. The closer the fuels are in price, the lower the fuel cost savings will be during Dual-Fuel mode. In addition to fuel cost saving, engine maintenance savings (as explained above) may also contribute to the economic benefit of Dual-Fuel operation.

Answer- Yes. As there are no changes in the engine compression ratio, cylinder heads, or basic operation as diesel cycle engine and furthermore, the sophisticated PLC-controlled dual fuel system is a cutting-edge technology, that relates to the engine on fumigation process principle, and so can be converted back to dedicated diesel engine as needed.

Answer- Details of Gas Train: Details of the mechanical and instrumentation specifications of gas train will be explained through the corresponding PI& D’s upon order placement. Also, during commissioning a Guzil Natgas team will supervise the erection of the gas train.

Answer- Gas in Gas train section from low pressure regulator to the Dual Fuel diffuser will be at zero pressure thus reducing the risk of high-pressure leakage into engine room compartment and explosion. When the dual fuel system is deactivated, there will no gas in this section of the gas train.

Answer- The dual fuel system does not have an engine power requirement in order to run.

Answer- The dual-fuel system requires very little/minimum maintenance- thus significantly reducing related costs.

Answer- 1. To perform detailed simulation of the fuel combustion, engine performance and exhaust emissions. 2. To study the trends of the performance parameters at different engine load conditions with varying natural gas substitutions. 3. To determine the safe limit of natural gas substitution without excessive rate of increase of cylinder pressure rise, which might compromise the mechanical integrity of the engine. 4. Investigate the effect of injection timing for the exhaust emissions and maximum cylinder pressure. The afore-stated CFD is therefore required to meet the safety and performance requirements of dual fuel conversions.