BENCH-SCALE MEASUREMENTS OF REFRACTORY CORROSION BY FLOWING CORRODENTS

摘要

To reproduce flowing slag conditions that occur in coal-fired power systems, the University of North Dakota Energy & Environmental Research Center (EERC) has constructed a bench-scale test system. Named the Dynamic Slag Application Furnace, or DSAF, it can be used to measure the rates and mechanisms of flowing slag corrosion of refractory materials at up to 1600°C in air. The test is useful for directly predicting the lifetime performance of the materials in air-blown environments. Comparisons between static and flowing slag test results for silicon carbide- and alumina-based monolithic materials show that static tests give very poor indications of probable performance in an operating system because the initial slag charge often soaks into the refractory. In addition, static tests do not simulate the erosion processes that can greatly increase the loss rate. Using the DSAF, EERC researchers have been working with the Plibrico Company of Chicago to develop new types of castable refractories that are much more resistant to flowing slag corrosion than commercially available materials. Tests with both high-rank and low-rank coal slags show that it is not possible to choose one refractory composition that is universally resistant to all coal slags. However, if refractory composition is correctly matched to the slag composition, lifetimes can be dramatically extended. In addition, small amounts of coal additives can significantly reduce the corrosivity of the slag both by affecting the viscosity of the slag and the ability of the slag to dissolve the refractory. In this paper, we present a detailed description of the DSAF system and describe pertinent testing procedures. Comparisons between results obtained by static versus dynamic slag testing are reported, and the results of tests of monolithic refractories are described along with methods for reducing coal slag corrosion of refractories through the use of coal additives.