Bi-Fuel Engines Reduce Operating Costs and Extend Run-Time

Posted on August 19, 2013 by

Many operators of diesel engines are installing equipment to reduce fuel costs by converting their engines for bi-fuel operation with natural gas.  Substitution rates of up to 80% can be achieved, leading to substantially lower fuel expense due to the lower price of natural gas.  Operating hours possible without re-supply of diesel fuel can be extended as well.

Several companies are on the market offering bi-fuel conversions.  Operators should take care to select the technology that best suits their engine operating requirements to protect their engine from damage due to excessive combustion temperatures.

There are two basic technology choices for bi-fueling a diesel engine.   The most common,  and less expensive alternative is known as “fumigation”.  With this technology, a gas mixer is added to blend natural gas into the combustion air intake prior to the engine turbocharger.  A controller monitors gas pressure, manifold pressure and exhaust temperature, as well as engine “knock” or detonation, controlling gas volume within safe limits.  No modifications to the engine’s diesel fuel injection system are required.  This technology has proven reliable and successful for engines operating under a relatively steady load.

For engines operating in variable load conditions, it is recommended that the bi-fuel system use direct injection technology.  In this method, very precise, fast acting magnetically operated valves are installed on each cylinder head, or on the intake manifold close to each cylinder head.  The right dosage of gas is introduced for each cylinder, enabling excellent load response,  with adjustment of gas volume from cylinder to cylinder enabling an optimized substitution rate, and better margin of safety from overheating the cylinder heads.  Because no mixture of air and gas is in the manifold, the risk of backfire is eliminated.

A vital safety component to any bi-fuel application is a very reliable and fast acting detonation control system.  This device must continuously monitor vibration signatures from each combustion cylinder in order to detect pre-ignition of fuel, and reduce gas volume before the engine is damaged.

As a leading manufacturer of gas and diesel engine controls selected by engine manufacturers worldwide, Heinzmann offers both fumigation and direct injection bi-fuel systems.  The Heinzmann Ariadne Knock Control unit monitors each cylinder on a cycle by cycle basis, enabling the engine to be safely run near the knock limit and thereby increasing efficiency and fuel substitution rate.   A complete engine management solution can be offered to suit specific client requirements.  Kraft Power offers turn-key bi-fuel conversions with Heinzmann controls.  Please contact us for further information!

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