Alfa Laval Fuel Oil Cleaning Unit Solutions (FOCUS) are automated modular systems for purifying the liquid fuel oils used in gas turbine power plants.
The fuel cleaning process is designed to prevent the potentially harmful effects of contaminants often found in fuel oil, using a complete, pre-configured system with all sub-systems integrated effectively.
The liquid fuels used in gas-turbine power plants vary substantially in their physical properties and the amounts and types of contaminants they contain. The trace metals sodium and potassium are often present, as well as water and a range of solid particles. Such contaminants cause high-temperature corrosion, the formation of ash deposits and clogging of the fuel supply system, resulting in costly operating problems and downtime that affects revenue earning in the power plant.
However, with correct treatment prior to use, it is possible to employ a wide range of liquid fuels in any modern gas turbine power plant. By ensuring consistent compliance with specific fuel oil purification requirements, an Alfa Laval FOCUS (Fuel Oil Cleaning Unit Solutions) unit helps ensure extended turbine service life as well as a significant reduction in operating costs via less maintenance and downtime.
A FOCUS installation contains all the equipment necessary for cleaning fuel oil effectively and at low cost in a straightforward, compact and robust modular unit that provides automatic, unattended operation, if required. Using a FOCUS unit for fuel oil cleaning makes it possible to do away with pre-filtration and problems with disposing of contaminated filter cartridges, and ensure reliable operation and exceptional separation efficiency at all times.
How it works
Alfa Laval centrifugal separator technology is the heart of the FOCUS modular cleaning installation. It provides a reliable, consistent way to remove both solids and water from fuel oils, at the same time.
A continuous flow of untreated fuel oil is fed via suction strainers to the separator, where any water and solids are separated from the fuel oil by the action of centrifugal force. This separation takes place in a rotating bowl. When the water seal has been established, the feed is introduced to the bowl inlet. This special Optiflow inlet is equipped with a system of circular discs that accelerate the feed before it enters the disc stack, to improve the efficiency of the centrifugal separation.
The oil is forced towards the centre of the bowl through the disc stack. A built-in paring disc pump discharges cleaned oil in a continuous flow. Separated water rises along the outside of the disc stack and is continuously discharged by a paring disc in the water outlet. The sludge and solid particles removed from the fuel accumulate around the periphery of the bowl and are discharged at intervals, before they build up to a point where they would interfere with separation. This discharge cycle is determined either manually from the control panel or automatically via the electronic control system once a pre-set time cycle has been completed.
The water and sludge removed by the centrifugal separators collect in the sludge tank and are transferred to the waste treatment system by a pneumatic pump controlled by level switches. An oil and water monitor in the purified fuel oil discharge line checks the quality of the oil leaving the centrifugal separators. This system is specifically designed to determine the exact amount of water left in the oil stream, with exceptional accuracy.
All aspects of FOCUS operations are controlled and monitored from one central console using a state-of-the-art PLC-based control panel.