Large pieces of rock, over 5 inches (125mm) in diameter, were mixing with the fuel at a Midwest United States power plant. With no crusher in the fuel handling system and the mills unable to crush the rock, the plant was experiencing mill outages regularly due to wear and damage from these large rocks. The numerous forced outages and de-rates were severely impacting the operational efficiency of the plant.
To address the problem of oversized, dense material causing unnecessary mill trips, Benetech engineered an advanced flow design chute with a stationary screening system incorporated as a replacement for one of the transfer points. The new screen system incorporated an additional, new chute leg to discharge the oversize material for inspection and disposal. In addition, the Benetech team worked with the plant to redesign and install a chute conveyor access system that needed to be relocated in support of this advanced screen system.
Screen Theory of Operation
The material discharged from the head pulley is concentrated through a flow deflector in the headbox, directing the concentrated flow towards the screen. Once engaged at the screen, the oversized material is separated and flows into the oversized containment chute. The undersized material continues through the normal coal path to the plant. The process of engaging the concentrated flow onto the screen is designed to help promote self-cleaning, minimizing build-up. The screen is flanged to allow for easy inspection and maintenance access. Inspection doors integrated into the design allow for ease of maintenance and removal of screen for maintenance.
Since start-up with the advanced screening system, the plant has had ZERO instances of pass through rock, causing forced outages or de-rates. This has been a major success for the plant and allows them to operate efficiently as expected.