The present invention provides improved boiler assemblies (10) with enhanced
pollution abatement properties through injection and recycling of particulate
sorbent materials including
sodium bicarbonate,
trona, and mixtures thereof. The assemblies (10) include a boiler (12),
economizer (14),
air heater (15), and recirculation reactor (16).Fresh
sorbent material is introduced via
assembly (60) into the boiler
assembly (10) at one or more injection locations, and serves to sorb
NOX, SOX, and other pollutants in the
flue gas. The
flue gas and entrained
sorbent material then pass through reactor (16) for separation of sorbent, which is then recycled for injection back into the
assembly (10) upstream of reactor (16). In another aspect, the invention provides
pollution abatement apparatus (110) and methods employing an upstream recirculation reactor (114), a supply of fresh sorbent (118), and a downstream collector (116). In the reactor (114), fresh sorbent reacts with incoming hot
flue gas (112) to generate a reduced
pollutant flue gas (128) and a solids fraction including reacted sorbent and pollutants, and unreacted sorbent. Recirculation apparatus (120) provided between the reactor outlet (126) and reactor (114) serves to generate a substantially constant
mass or volume flow rate of the reactor solids fraction, which minimizes the use of fresh sorbent and maximizes the
pollution abatement efficiency of the apparatus (110).