Analysis of a Failed Separation Cyclone from the Dow Chemical Corporation Slagging Coal Gasification Plant

摘要

A failed Type 310 stainless steel cyclone separator from Dow Chemical's 12-ton-per-day slagging air-blown gasifier pilot plant located near Plaquemine, LA has been analyzed. Samples of material from the upper portion of the cyclone were found to be deformed, heavily oxidized at the inner surface, and extensively perforated by flaws and cracks which had initiated at the inner surface. The sample from the lower portion of the cyclone was not significantly deformed, was less heavily oxidized, and was not perforated. A three-layer oxide was found on the inner surface of the cyclone, with the top-most layer containing ash particles embedded in Fe sub 3 O sub 4 , the intermediate layer consisting of mixed iron and chromium oxides, and the bottom layer consisting almost entirely of chromium oxide. The failure is attributed to the combined effects of high-temperature oxidation and erosive wear at the inner surface, with no significant contribution to failure by sulfidation. It is recommended that for increased life the cyclone be lined with a high-alumina castable refractory lining of the sort used for erosive-wear resistance in petrochemical plants and other coal gasifiers. (ERA citation 09:009220)