Does anyone have experience with a rapid buildup of a light, fluffy, gray, slightly magnetic deposit on the tube side (reaction furnace exhaust gases) of an HRSG? We have sent it to the lab for analysis but don’t have the results back yet. This material was found in both the hot pass and cold pass of the HRSG, with slightly more deposit density in the cold pass. We just retubed this steam generator and replaced the refractory in the reaction furnace in June 2009. Any ideas?
I have heard of at least 2 other plants with loss of heat recovery (i.e. increased temperature at the WHB outlet). No definitive explanation since both are still operating. Is this a common problem? Is it refractory-related? Dry-out/cure of refractory? Improper refractory?
Your other post mentions water-side fouling in the WHB. A good cleaning to remove surface scale and rust is essential before startup. See my post there.