Safety and reliability are critical considerations for all power plants, and an important part of the safety systems are the boiler feed pumps. Pumps must maintain continuous operation under the most difficult conditions. Even after long standby periods, pumps must be ready to immediately start and run up to full load as soon as an alarm is triggered.
In the typical process plant, the boiler feed water pump is a multistage, horizontally-split, between-bearings design that is heavily dependent upon the wear components for rotor stability. Short periods of run-dry as the pump starts can provoke corrosion. These issues decrease reliability of the pumps and increase repair and preventive maintenance costs. Hence, material selection becomes very important to ensure long-term reliability in this service.
ACB India Ltd., a private power plant operator supplying electricity to the main grid was facing the challenge of immediate stoppage of boiler feed pump due to tripping. During this period of dry run the pump is subjected to run dry situation for short periods. The metallic wear parts of the pump like rings, inter-stage bushings and balance disc, used to wear out within 3 to 4 months.
Over the years ACB was losing a lot of money due to frequent replacement of the wear parts. The increase in clearances at wear parts was also causing reduction in efficiency and corresponding increase in the motor input power.
DuPont collaborated with its challenge partner, Mascot Dynamics Pvt. Ltd., to replace metallic wear rings with DuPont™ Vespel® CR-6100 for boiler feed pumps at ACB India Ltd.
Vespel® CR-6100 is easily machinable and low wear rate, low coefficient of friction, low coefficient of thermal expansion, resistance to thermal shock and durability of vespel® CR-6100 are attributes in boiler feed pump wear ring and under pump operating conditions such as extreme cavitation and high vibration. This enabled zero breakdowns through improved operating efficiency, increased equipment reliability and avoid the seizing or galling problems encountered with metal components.
DuPont™ Vespel® CR-6100 bowl wear rings and column bushings for boiler feed pumps have been proven to provide reliable performance that platform engineers can trust. Because of its composite nature, low coefficient of friction and low wear, Vespel® CR-6100 components can withstand run dry operations which increased reliability and reduced maintenance costs.
Wear components such as wear rings, throat bushings and line shaft bearings manufactured from Vespel® CR-6100 exhibit: