Electric Motor Conversion of 2-Stroke & 4-Stroke Integral Engines
Other options for extending the operating life of existing integral engines is conversion to electric motor drive. This type of retrofit consists of removing power end components while retaining and utilizing frame, running gear and compressor cylinders. A synchronous or induction motor is coupled to the engine crankshaft by direct coupling, flex coupling or for low horsepower applications belt drive. Where electric utility infrastructure exists, and electricity rates are cost effective, this type of retrofit may make sense. Factors that justify this conversion are elimination of exhaust emissions, reduced maintenance and operations costs, reuse of existing frame, running fear, compressor cylinders, pulsation vessels and process piping. Additional benefits are reuse of existing foundations building infrastructure and reduced overall installation costs. The first step is a feasibility study analyzing torsional vibration, crankshaft stress, unbalanced forces and moments, starting torque, general arrangement and engine layout. In some cases, space constraints and engine layout prevent the retrofit. A secondary issue is the ability of the engine crankshaft to handle stresses and torsional vibration from a motor drive. If the crankshaft is deemed unsuitable, a new crankshaft design can be developed. Three case studies will review the retrofits of HSRA, KVSR and XVG engine models.