Performance of Hot Gas Clean-Up Devices Tested at the NYU DOE-PFBC Facility

Abstract

Three hot gas clean up units namely, the Screenless Granular Bed Filter (GBF), Ceramic Cross-flow Filter (CXF) and High Temperature, High Pressure Electrostatic Precipitator (ESP) designed for PFBC combined cycle power applications were tested at the New York University (NYU) DOE-PFBC facility located at Westbury, New York using a 780 mm ID pressurized fluidized bed combustor. The combustor was operated up to 10 atma and 870 °C. With the exception of the ESP whose performance was hampered by persistent electrode bushing failure, the particulate capturing efficiencies of the GBF and the CXF were predominantly in the upper 90 % range. The dust loading leaving the filters was consistently lower than the NSPS particulate emission limit. The results also indicate that the filter exit gas stream may meet the gas turbine particulate tolerance limit. None of the three high temperature, high pressure (HTHP) gas clean up units tested emerges as a favorite for use in cleaning PFBC exhaust stream because, each has mechanical design as well as operational flaws which could be corrected. The Cross-flow filter suffered from filter element cracking or delamination or gasket failure during its short test program. The backpulse cleaning system also needs to be optimized. The GBF is susceptible to media bubbling and granule flow problems through its lower seal leg. The Electrostatic Precipitator tested at NYU failed because its electrode bushings cracked due to overheating and could not hold their designed voltage. Further HTHP filter testing at the sub-pilot plant scale is necessary to optimize filter design and develop effective operational procedures for the hot gas clean up systems that will make them viable for commercial PFBC application.