KANSAS CITY POWER & Light (KCPL) needed to upgrade the feeders at its La Cygne and Itan coal-fired power plants. At La Cygne, one surge bin supplied three vibratory feeders delivering coal to three crushers. When the coal was wet or frozen, operators had to turn up the feeders, and impact and shock literally tore the feeders apart. Also, the increased noise level was deemed unacceptable.
The utility chose Roberts & Schaefer, engineering contractors, to supply an upgrade. “KCPL hired us to upgrade the entire coal handling operations including the crusher building at the La Cygne station. The building was an early target for an upgrade,” said Chuck Tulley of Roberts & Schaefer. “We quickly realized that elimination of the vibratory feeders would substantially reduce the exorbitant amount of dollars spent on maintenance, repair and downtime. A new crusher configuration with the two belt feeder conveyor system was the answer to easily handle the utility’s required throughput.”
Now, at La Cygne, 15 percent local and 85 percent Powder River Basin coal is dumped into a huge surge bin. New 10-ft. wide feeder belt conveyors, installed tail-pulley end to tail-pulley end are positioned under the surge bin. This arrangement keeps a steady supply of pre-screened coal-up to 1,000 tons/hour-flowing to two hammer mill crushers. “Key to the success of the feeder belt conveyor system is an outboard tail pulley/belt tensioner combination that narrows the gap between tail-pulleys. The full dump capability of the surge bin is used to maintain a constant and uniform flow of coal without concern for spillage in the tail-pulley gap,” Tulley said. KCPL used 300 and 400 series Telescopers, greatly reduce tensioning problems while breaking in new belts. They also speed bearing changes.
The feeder belt speed is slow, but adjustable to regulate the amount of coal needed to meet power demand at the baseload station. Each crusher can handle 600 tons/hour of coal.
Conventional feeder belt conveyors were dismissed early in the design effort because the metal frame and pillow block arrangement interfered with the design and occupied too much space at the tail pulley end. “Our recommendation to install Telescopers solved a tail pulley clearance dilemma. The take-up’s telescoping tube design eliminates the need for conveyor frames that extend beyond the pulley. In the new design, pillow block bearings are mounted directly onto the slider tube’s bearing plate,” Tulley said.
The success of this upgrade convinced KCPL to duplicate the system, on a smaller scale, at its Itan generating station.
KCPL’s La Cygne station is a coal-fired baseload facility serving more than a million residents in 23 counties of northwestern Missouri and northeastern Kansas.