Evaluation of Zero Compressor Wash Routine in RN Service

In order to maintain engine performance and prevent the build up of airborne particles within compressor systems, the Royal Navy (RN) has traditionally employed a compressor cleaning routine on all marine gas turbines. This routine consists of turning the engine using the starter motor whilst spraying the cleaning medium (water or water and detergent) into the intake. The cleaning medium is driven through the engine, cleaning the compressor as it goes. The wash effluent is then drained away via the engine drains. Although most gas turbine users use similar routines, the harsh, salt laden marine environment presents a unique challenge to the Naval operator. In order to evaluate the current level of compressor washing, ascertain effects on performance and corrosion and investigate potential cost savings, the RN initiated a trial whereby 2 Rolls-Royce SM1C marine Spey’s were subject to a zero wash routine. The two ships involved, HMS Richmond & HMS Northumberland, accumulated approximately 750 and 1500 unwashed operating hours respectively. As the Original Equipment Manufacturer (OEM), Rolls-Royce was closely involved with the project and inspected the engines throughout the trial. The trial concluded that significant operational benefits could be gained by modifying the existing wash routine, adopting a new cleaning medium and extending the wash periodicity. In addition, the report concluded that engine performance and cleanliness would not be affected by altering the wash routine. The paper will discuss the background to the trial, explain the methodology used, explore the conclusions and discuss the benefits derived from the trial, including applicability to other marine gas turbines.