Posted by Donald Ring on July 27, 2000 at 10:28:21:
We have a Foster Wheeler natural circulation boiler. It is a vintage 1950's boiler. Over the past year, we have been experiencing an unusually high number of short-term overheating failures in a localized area of the waterwall screen tubes. The tubes are in the convection pass of the boiler. We have done a number of things but have not been able to determine a root cause. There is no blockage in the tubes and no combustion problems. The only thing we have found is a 3-inch layer of deposits in the bottom of the steam drum. The deposits are under the girth baffles in crossover flues that connect the front and rear horizontal separator circuits of the steam drum. The girth baffles direct the steam/water mixture into the horizontal separator to provide steam-free water to the downcomers.
We also have tubes misaligned in the area of the short-term overheating failures.
Could these two problems together equate to short-term overheating failures ???
Has anyone experienced these type of failures with no tube blockage or combustion problems???
Any help would be greatly appreciated.