MATERIALS EXPOSURE TEST-RESULTS AND POSTTEST EXAMINATION OF CONSTRUCTION MATERIALS USED IN HYCOL COAL-GASIFICATION PILOT-PLANT

This paper describes the corrosion test results obtained from the fiel d exposure test of commercial alloys for about 2100 hours. Post-test e xamination of various construction materials used in HYCOL coal gasifi cation pilot plant was also included. Materials exposure tests were ca rried out in the heat recovery boiler section with uncooled coupons lo cated at four different temperature zones from 400 to 700 degrees C. A lloys with Cr contents greater than 12% performed best in the all test conditions. Corrosion losses of the specimens used in tests with freq uent downtime were found to be higher regardless of their Cr contents. Various pilot plant components were inspected at the site from the ma terial standpoint of view after the completion of the planned performa nce tests, some of which were cut out and analysed in the laboratory. The major causes of damages of the metallic materials observed by post -test examination were sulfidation-oxidation of the heat exchanger tub es during high temperature operation, and dew point or downtime corros ion such as intergranular cracking and pitting. Refractory materials f or the gasifier had been deteriorated by dissociation related with mol ten slag penetration.