Hydrated lime injection system

Flue gas desulfurization is a process to reduce SOX, NOX emissions from industrial combustion, especially coal fired power plant. FGD could be classified into wet, dry or semi-dry process.

Dry sorbent injection is a method by introducing an alkaline material (usually limestone, hydrated lime, dolomite, sodium bicarbonate) into flue gas stream. By chemical reaction with acid gases, these alkaline matters will turn SO2, SO3 into gypsum finally. Injection location could be boiler furnace, ducts or individual reactor. Chemical sorbent in dry powder form could avoid dew point corrosion in wet FGD process. This process has advantages like no wastewater, no secondary pollution, etc.

As circulating fluidized bed boiler could burn sufficiently and keep combustion temperature stably around 800-900℃, which is optimal for the reaction of limestone/dolomite, injection into CFB boiler furnace could effectively remove 90% sulfur. For other boilers, injection into furnace could achieve only 25-35%. To improve sulfur removal, wetting process at ducts by spraying water to increase flue gas humidity could increase it to 75%. Plus the circulation of slurry, total could be 85%.