Performance of a Vacuum Formed Chopped Ceramic Fiber Filter in a Reducing Environment

Abstract

A laboratory-scale apparatus has been used for unattended, long duration, continuous flow through testing of a vacuum formed chopped ceramic fiber filter under reducing conditions at atmospheric pressure. Four candle specimens were exposed from 150 to 3550 h to 600°C gas containing 4 percent CO, 11 percent H2, 12 percent CO2, 14 percent H2O, 59 percent N2, 1 ppmv NaCl, 50 ppmv H2S, and 1000–2000 ppmw ash from a transport reactor operated in gasification mode. A database was established on pressure drop of the as-received and exposed filter as a function of face velocity and temperature. Tests were conducted to investigate the effects of back-pulse parameters on filter regenerability. Results are reported on the critical reservoir pressure and pulse duration for maintaining a stable saw-tooth profile of pressure drop across the filter element. Data are obtained to characterize the effect of chemical and thermal aging on the apparent bulk density of the filter, pore size distribution, fast fracture strength, and microstructure. It is suggested that the compliant filter undergoes a slow process of rigidization upon exposure to the test environment.