This is the nineteenth Technical Progress Report submitted to the Department of Energy (DOE) in connection with the cooperative agreement between the DOE and Ohio Power Company for the Tidd PFBC Hot Gas Clean Up Test Facility. During this quarter, the Tidd Hot Gas Clean Up System operated for 444 continuous hours (including 15 hours at the end of the first quarter) during Test Run 18. The system was shut down on April 18, 1994, and remained out of service for the remainder of the quarter. Highlights of this period are summarized below: operated HGCU for 444 continuous hours which was the longest run so far in 1994; completed Hazardous Air Pollutant testing; inspected Advanced Particle Filter (APF) following testing and found 28 broken filter candles; cleaned and reassembled the APF without the inner rows of candles in the upper and middle plenums since ash bridging between these candles and the center support pipe caused the candle failures; installed 30 new filter candles of different materials for testing in the APF; and installed additional air piping and valves to permit the primary cyclone to be totally spoiled in service and thereby direct all of the ash into the filter.