A Review of Gas Turbine Online Washing Systems

Abstract

The power and efficiency of gas turbines heavily depends on the state of the compressor. Being exposed to atmospheric conditions and pollution, fouling degrades the compressor in terms of the airflow passing and efficiency. Modern online compressor washing techniques prevent a large build up of debris by injecting washing fluid upstream of the compressor. For a satisfactory power recovery, washing methods and schemes have to be carefully adapted to the engine geometry, atmospheric and operating conditions. Therefore, the achievement of a universal cleaning procedure seems to be unlikely and only few general requirements and guidelines concerning compressor washing are available. There also is a variety of different washing systems in existence. These are either provided by the gas turbine manufacturer along with the gas turbine itself or designed by system suppliers as a retrofit for gas turbines of all makes. Based on a literature review and a patent search, a historical review of online washing systems was carried out. Different approaches and cleaning philosophies became apparent. The main influencing factors for the design of washing systems were summarized and basic categories of systems were elaborated to characterize the state-of-the-art in compressor washing equipment. A survey of installations and washing procedures used by European power plants and recommendations by major gas turbine manufacturers and system suppliers for retrofits complemented the existing data sets from the literature. The field data supported the introduced categories for online washing systems. In particular, the air/fluid ratio was shown to be a significant parameter to describe a washing system.