Abstract
This paper describes and analyzes recent utility operating experience with materials of construction in full-scale wet FGD systems on boilers burning eastern or western coals. The systems include mainly limestone, lime, and alkaline fly ash wet scrubbing, but there is also representation by double alkali, non-recovery soda ash, and Wellman-Lord wet scrubbing processes. Information on field performance of construction materials was collected primarily by visits to FGD installations, but also by contacts with FGD process and materials suppliers. Information was collected for the following FGD system components: prescrubbers, absorbers, spray nozzles, mist eliminators, reheaters, fans, ducts, expansion joints, dampers, stacks, storage silos, ball mills and slakers, pumps, piping and valves, tanks and thickeners, agitators and rakes, vacuum filters and centrifuges, sludge pond and landfill linings, and regeneration equipment. Materials description and analysis includes successes, failures, reasons for success or failure, failure mechanisms, and relative costs of various materials.
Outlet ducts downstream from the outlet dampers and stack linings have a significant history of materials problems and are critical components in that failures may require complete boiler shutdown and loss of generating capacity for lengthy periods. Prescrubbers, absorbers, reheaters, outlet ducts upstream of the outlet dampers, dampers, pumps, piping and valves, and thickeners have a moderate history of materials problems but failures may not require complete boiler shutdown. Spray nozzles, mist eliminators, fans, inlet and bypass ducts, expansion joints, storage silos, ball mills and slakers, tanks, agitators and rakes, vacuum filters and centrifuges, sludge pond and landfill linings, and regeneration equipment have a relatively low history of materials problems and/or are amenable to rapid repair or replacement.
