Spray drying apparatus for dehydrated filtrate and air pollution control system

A spray drying apparatus for dehydrated filtrate from which gypsum from desulfurization wastewater from a desulfurizer is separated, comprising:

• a spray nozzle for spraying the dehydrated filtrate into a spray drying apparatus body via a dehydrated filtrate feed line;
• an introducing port provided in the spray drying apparatus body, for introducing flue gas to dry the dehydrated filtrate sprayed from the spray nozzle;
• a drying region formed in the spray drying apparatus body, for drying the sprayed dehydrated filtrate with the flue gas;
• a discharge port for discharging the flue gas contributed to the drying;
• and
• a wash nozzle for supplying the dehydrated filtrate via a washing liquid feed line so as to wash the spray nozzle and the inside of the apparatus body, the washing liquid feed line being branched from the dehydrated filtrate feed line, wherein
• when it is determined to be spray failure or dry failure of the spray nozzle, the supplying of the flue gas into the spray drying apparatus is stopped, the spraying from the spray nozzle is stopped, and the washing for the apparatus body by the wash nozzle is performed.