Industrial gas turbines are used in plants throughout the power industry. While these turbines can be very effective in generating power, fouling on the compressor blades of a gas turbine can diminish performance of the turbine and reduce the power output of the plant. The cause of fouling comes principally from dust and lubricating oil leakage from the compressor’s main bearings. This results in a buildup of oily dirt and dust that causes increased surface roughness that can result in pitting of the blades. Performance gains of 2 to 4 percent are often achieved by regular cleaning. Using a turbine and compressor wash can help achieve a cleaner system.
Plant operators are increasingly configuring their wash units as modular skid systems in order to reduce site disruption and simplify the process. This post discusses level solutions for turbine and compressor wash skids and is part of an occasional Magnetrol® blog series on modular skid systems.
Turbine and Compressor Wash Skids
Online/offline wash skids are used to store, pump and heat solutions for cleaning turbine blades and vanes. Skids range from small, wheeled carts to large, fixed-skid installations that clean multiple generators.
Turbine and compressor wash skids typically consist of an electric heater, cleaning solution, mixing and storage tanks, wastewater tanks, control system, pumps, instrumentation, valves and interconnects. Updated water wash pumping systems use a variable frequency drive (VFD) to accurately control high-pressure water flow.
1. Cleaning Solution Mix Tank
Mixing and blending the detergent concentrate with water is essential to the cleaning operation. An impeller in the mixing vessel accomplishes the blending of water and concentrates. Level controls monitor the mix tank and trigger alarms in the event of tank underfill or overfill incidents.
Continuous Level: Eclipse® Model 706 Guided Wave Radar Transmitter; Pulsar® Model RX5 Radar Transmitter or Model R82 Radar Transmitter
Point Level: Model B35 External Cage Float Switch; or Echotel® Model 940/941 Ultrasonic Switch
2. Detergent Concentrate Storage
To create the turbine wash solution, precise quantities of detergent concentrates are injected into the mix tank by a metering pump system. Concentrate storage tanks require stringent level monitoring in order to maintain continuous availability of the cleaning solution.
Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter; E3 Modulevel® Displacer Transmitter; PULSAR Model R96 Radar Transmitter or Model R82 Radar Transmitter
Point Level: Tuffy® II Float Level Switch or ECHOTEL Model 910 Ultrasonic Switch
3. Cleaning Solution Storage Tank
The process-ready cleaning solution is stored in a metal or plastic tank. Tank level controls actuate tank-filling operations and protect against underfill and overfill conditions.
Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter; E3 MODULEVEL Displacer Transmitter; PULSAR Model R96 Radar Transmitter; Model R82 Radar Transmitter or ECHOTEL Model 355 Non-Contact Ultrasonic Transmitter
Point Level: TUFFY II Float Level Switch or ECHOTEL 910 Ultrasonic Switch
4. Spent Wash Solution Tank
Spent water wash is collected in a dedicated collection tank and is periodically discharged as wastewater. Level monitoring will actuate fill valves and trigger an alarm in the event of an overfill incident.
Continuous Level: ECLIPSE Model 706 Guided Wave Radar Transmitter; PULSAR Model R96 Radar Transmitter; Model R82 Radar Transmitter or ECHOTEL Model 355 Non-Contact Ultrasonic Transmitter
Point Level: TUFFY II Float Level Switch or ECHOTEL Model 961/962 Ultrasonic Switch