Abstract: A humidity sensor and filter assembly are housed within a cylindrical barrel that is positioned in a process gas stream such as combustion flue gas. A portion of sample flue gas is conducted through the barrel and the filter assembly past the sensor located inside the filter so that accurate humidity measurements can be taken. Unwanted flue gas particulate matter accumulated on the outside surface of the filter is ejected by pulsed purge gas admitted into the filter to reverse the flow through the filter. In one embodiment a heat exchange chamber preheats the purge gas. In another embodiment the pulsed purge is supplied by a reciprocal piston contiguous with the internal volume of the filter that reverses the flow through the filter using the process gas.

Abstract: Recirculation of treated flue gas either independently or as a substitute for ambient air at specific points of ingress in a flue gas treatment system is provided to stabilize approach temperature and related parameters such as reagent consumption and pollution admission rate preventing both the accumulation of particulate matter and excessive corrosion associated with ambient air ingress. This recirculation provides a desired turbulence within remote regions of the flue gas treatment system to reduce the amount of particulate matter that may otherwise settle and accumulate in the absorber vessel or other areas of the system thereby causing particulate matter to be conveyed to the particulate removal device.

Abstract: Recirculation of treated flue gas either independently or as a substitute for ambient air at specific points of ingress in a flue gas treatment system is provided to stabilize approach temperature and related parameters such as reagent consumption and pollution admission rate preventing both the accumulation of particulate matter and excessive corrosion associated with ambient air ingress. This recirculation provides a desired turbulence within remote regions of the flue gas treatment system to reduce the amount of particulate matter that may otherwise settle and accumulate in the absorber vessel or other areas of the system thereby causing particulate matter to be conveyed to the particulate removal device.