Evaluation of slag and refractory compatibility for low-Btu gasification of coal for electric power generation. [22 refractories

Abstract

Bench scale evaluation tests were made on candidate refractory materials considered for use within Combustion Engineering's atmospheric pressure, entrained bed, 5-ton-per-hour coal gasification Process Development Unit (PDU). Bench-scale dynamic slag tests, found to be comparative within a given test, produced relative wastage rates of 1 x 10/sup -3/ in./sup 3//in./sup 2/ hr for the best alumina--chromia refractories to 225 in./sup 3//in./sup 2/ hr for a 70 percent alumina firebrick. Alumina--chromia refractories with all types of bond schemes did well; fusion cast refractories gave best results. Basic refractories (magnesio--chromite) showed good corrosion resistance, however, uncombined magnesia was dissolved by the coal ash slag. Tests showed that the simulated product gas (without the presence of slag), did not degrade the physical integrity of phosphate-bonded, high-alumina refractories after exposure at 1700 to 2200/sup 0/F for 100 hr nor at 2600/sup 0/F for 50 hr despite phosphorus loss. Tests with dry (dew point approximately -60/sup 0/F) 8 percent hydrogen-92 percent argon showed phosphorus was lost by reduction of P/sub 2/O/sub 5/ and volatilization of elemental phosphorus at the test temperatures with subsequent deposition of the elemental phosphorus in cool components down stream. Similar tests with wet (dew point approximately +85/sup 0/F) 8 percent hydrogen-92 percent argon also caused a phosphorus loss with condensation of phosphoric acid upon cooling. Recommendations were made that the findings of this study be correlated with results obtained from a post operative examination of the refractories exposed to the actual environment established in the PDU. This correlation would aid in establishing future laboratory procedures for selecting refractories.