Performance of a vacuum formed chopped ceramic fiber filter in a reducing environment

A laboratory-scale apparatus has been used for unattended, long duration co ntinuous flow through testing of a vacuum formed chopped ceramic fiber filt er under reducing conditions at atmospheric pressure. Four candle specimens were exposed from 150 to 3550 h to 600 degreesC gas containing 4 percent C O, 11 percent H-2, 12 percent CO2, 14 percent H2O, 59 percent N-2, 1 ppmv N aCl, 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 pr essure and pulse duration for maintaining a stable saw-tooth profile of pre ssure drop across the filter element. Data are obtained to characterize the effect of chemical and thermal aging on the apparent bulk density of the f ilter, pore size distribution, fast fracture strength, and microstructure. It is suggested that the compliant filter undergoes a slow process of rigid ization upon exposure to the test environment.