A REVIEW OF INFORMATION RELEVANT TO TUBE CORROSION IN A GAS-COOLED, COAL-FIRED, ATMOSPHERIC-PRESSURE, FLUIDIZED-BED FURNACE

摘要

The fluidized-bed combustion unit being developed for the coal-fired Modular Integrated Utility System (MIUS) will drive a gas turbine in a Brayton cycle and is characterized by a large surface area operating at a high metal tempera¬ture and at low heat fluxes. For the generation of about 350 kW(e), 47.4 m2 (510 ft2) of metal surface in the form of 560 13-mm (1/2-in.) tubes will be in contact with the bed and will operate at about 844°C (1550°F). The tube wall will be on the order of 1.8 mm (70 mils), and the tubes must be sufficiently strong to withstand the normal body forces from the fluidized bed. It is desirable for the tubes to survive at least ten years of operation, which requires penetration rates not more than 0.08-0.13 mm/year (3-5 mils/year).nA large and diverse amount of material has been reviewed in a quest for definitive information relevant to corrosion in hopes for guidance in selecting an optimum material. A review was made of conventional coal-fired power plant boil¬ers, turbine bucket corrosion, corrosion work directed toward materials selection for coal gasification, and the informat on available from experience in the operation of other coal-filed fluidized-bed combustors. In each case it was found that important differences between our intended application and the" conditions under which the corrosion data were accumulated make translations of significance dubious. Through the rationale of qualitatively analyzing the most probable mechanism for corrosion in our system, the conclusion that the specified attack rates will not be exceeded for several practical materials was found reasonable.