Abstract
As a part of the on-going long-term materials testing program in the TVA 20-MW AFBC Pilot Plant, the Kentucky Energy Cabinet Laboratory has exposed corrosion test racks containing test samples of several engineering materials to the impingement environment of fuel/sorbent mixture feed and the recycle feed within the bed region of the combustor. The racks were located there in order to simulate the erosion-corrosion conditions that might exist if the feed jet were to impinge upon a tube bundle support structure member. After approximately 3,000 hours of exposure, the samples of type 304 ss, type 309 ss, RA 253 MA, chromized type 304 ss and aluminized type 304 ss, were analyzed for weight loss and corrosion microstructure. The results show that the weight loss suffered by the test materials subjected to the two feed jets [~ 0.38 m (15") from the feed point] was comparable to that observed elsewhere in the combustor at a similar exposure time. In both cases, corrosion microstructure observed in the uncoated alloys was typical of the well developed advanced stages of sulfidation/oxidation attack. Even though the combustor operations involved nearly 2 times more recycle material feed than the fuel/sorbent feed, corrosion was more severe in samples exposed to the fuel/ sorbent mixture impingement than in the samples exposed to the recycle.
