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The Department of Energy established a program at Battelle's Columbus Laboratories to obtain engineering data on the durability of candidate heat-transfer and structural support materials operating in an atmospheric-pressure fluid-bed combustor burning high-sulfur coal in the presence of limestone as a sulfur oxide getter. The research was done in Battelle's 24-in. dia fluid-bed combustor operating at 1620/sup 0/F, 8 ft/sec superficial velocity, 25% excess air, and 0.1 lb/MM Btu SO/sub 2/ in the flue gas (1.2 lb/MM Btu SO/sub 2/ is EPA's new source standard for large combustion equipment). Candidate heat-transfer materials investigated were FSX 414, 310, 304, 18-18-2, 347 stainless steels, IN 671, P9, and two coatings featuring Al and Cr; they were tested for 10,500 and 1500 h at 1100 to 1580/sup 0/F. Candidate support structure materials studied were 304, 310, 347 stainless steels, aluminized 304 and 310 stainless steels, and Alloy 825, all tested at 1620/sup 0/F for 1080 h. Results indicated FSX 414 and 310 SS as best for heat-transfer service, with Alloy 825 and 310 SS best for support structures. The severe erosion of several 316 SS bed-cooling tubes demonstrated the vulnerability of metal to erosion at temperatures too low for formation of protective oxidemore » scales. The results of a short supplemental program run with lower metal temperatures (400 to 910/sup 0/F) indicated a maximum in the observed metal loss (thickness) for several alloys, this occurring at 700 to 860/sup 0/F for 316 SS, 840/sup 0/F for E-Brite and 820/sup 0/F for P9. Individual particle velocity measurements in the bed showed 10% had velocities more than twice the superficial velocity with some five times that value.« less |
