Fluidised-Bed Combustion. IEA Grimethorpe Pressurized Fluidised-Bed Test Facility Back-End Valves: History and Modification

摘要

The pressure of the combustor freeboard is controlled by one of three back-end pressure control valves. The back-end valves are so called as they are situated at the back end of the exhaust gas system at the outlet of the main exhaust gas heat exchanger. In normal operation one of the valves is on pressure control duty, another on pressure relief duty, and the third is shut and available for operation on control or relief duty. These valves are subjected to a very arduous duty: temperatures of up to 350 exp 0 C to 375 exp 0 C with pressure drops of approximately 8 bar, and an estimated solids content of up to 400 ppM in the exhaust gases. Severe erosion on the valves seats, shafts, seals and upstream and downstream pipework has occurred and a large amount of remedial work has been carried out on the valves and adjacent pipework. This report describes the history of the valve erosion, the maintenance/remedial work carried out, and the steps being taken to attempt to solve the problem for future tests. (ERA citation 08:041968)