Abstract: A method and system for preventing exclusions in an air quality control system (AQCS) of a type having a scrubber, either a circulating fluidized bed (CFB), transport reactor (TR) or spray-dryer absorber SDA, and in all three cases with a flue gas recirculation FGR system. The invention automatically pre-heats flue gas recirculated to the input of the CFB/TR/SDA scrubber during periods of low temperature operation. The system supplements the “traditional” gas recirculation scheme with heater(s) that are used during periods of low temperature. During periods of low load conditions, the system monitors the SDA/TR/CFB inlet temperature and, when it falls below a setpoint, the control system increases the heat input of the pre-heater(s) in the FGR system in order to maintain a minimum inlet temperature.

Abstract: A method and system for automated control of the operating temperature setpoint of a circulating fluidized bed (CFB) scrubber within a pre-determined range of approach temperatures to the adiabatic saturation temperature of the CFB scrubber exhaust stream to maintain an optimal operating temperature, thereby reducing low temperature sulfuric acid corrosion and deposition of wet materials, and high temperature excess reagent use. A Dewcon® Moisture Analyzer (or equivalent) is connected in the exhaust stream of the CFB scrubber. The Dewcon® Moisture Analyzer transmits adiabatic saturation temperature data of the exhaust stream to the CFB scrubber system controller. Based on pre-programmed parameters, the system controller adjusts the CFB scrubber temperature setpoint.

Abstract: A method and system for automated control of the operating temperature setpoint of a circulating fluidized bed (CFB) scrubber within a pre-determined range of approach temperatures to the adiabatic saturation temperature of the CFB scrubber exhaust stream to maintain an optimal operating temperature, thereby reducing low temperature sulfuric acid corrosion and deposition of wet materials, and high temperature excess reagent use. A Dewcon® Moisture Analyzer (or equivalent) is connected in the exhaust stream of the CFB scrubber. The Dewcon® Moisture Analyzer transmits adiabatic saturation temperature data of the exhaust stream to the CFB scrubber system controller. Based on pre-programmed parameters, the system controller adjusts the CFB scrubber temperature setpoint.