Operating changes control scale in wet ash transport systems

Calcium carbonate scaling can result in an almost total blockage of the flow in a coal-fired power plant's recirculating wet ash transport system. Without sufficient flow, ash cannot be transported from the hoppers to the storage lagoons and eventually the plant must be derated or shut down. Improved monitoring and operating practices can often solve scaling problems better than costly treatment systems or new hardware. Examples are given to show how conventional operating policy decisions can affect scale formation. 8 refs, 3 figs.