Spray drying apparatus for dehydrated filtrate and air pollution control system

Abstract

A gas introducing port provided in a portion of a side wall near a top (lid) of a spray drying apparatus body, for introducing flue gas to dry spray liquid of dehydrated filtrate; a spray nozzle hung down from the top (lid) of the spray drying apparatus body, for spraying the dehydrated filtrate; a drying region formed in the spray drying apparatus body, for drying the sprayed dehydrated filtrate with the flue gas; a gas discharge port provided in a portion of the side surface near the bottom of the spray drying apparatus body, for discharging the flue gas contributed to the spray drying toward a gas feed line, which is a main flue gas duct; and a wash nozzle, which is a washing unit for washing the spray nozzle and the inside of the apparatus body with washing liquid are included.

1 . 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.   
     
     
         2 . The spray drying apparatus for dehydrated filtrate according to  claim 1 , comprising:
 a detection unit for detecting spray failure in the spray nozzle or dry failure;   a determination unit for determining whether spraying and drying states of the dehydrated filtrate are good or bad on the basis of a detection result from the detection unit; and   a control unit for suggesting or instructing washing of the spray nozzle and the inside of the apparatus body by the wash nozzle when it is determined to be the spray and dry failure as a result of the determination made by the determination unit.   
     
     
         3 . The spray drying apparatus for dehydrated filtrate according to  claim 1 , wherein
 the detection unit is any one of, or a combination of, a differential pressure gauge, a gas thermometer, a gas moisture meter, and a thermometer on a surface of the apparatus body.   
     
     
         4 . The spray drying apparatus for dehydrated filtrate according to  claim 1 , comprising:
 a cooling unit for cooling the inside of the apparatus body heated by air blow of the flue gas.   
     
     
         5 . The spray drying apparatus for dehydrated filtrate according to  claim 1 , wherein
 the discharge port is provided in a lower portion of the spray drying apparatus body and inclined toward an upper side of the spray drying apparatus body from a horizontal direction.   
     
     
         6 . The spray drying apparatus for dehydrated filtrate according to  claim 1 , wherein
 the washing liquid is any one of, or a combination of, the dehydrated filtrate, water, and steam.   
     
     
         7 . The spray drying apparatus for dehydrated filtrate according to  claim 1 , comprising:
 a washing liquid discharge line for discharging washing effluent from the wash nozzle.   
     
     
         8 . An air pollution control system comprising:
 a boiler for combusting a fuel;   an air heater for recovering heat of flue gas discharged from the boiler through a flue gas duct;   a precipitator for removing ash dust in the flue gas after the heat recovery;   a desulfurizer for removing sulfur oxides contained in the dust-removed flue gas with an absorbent;   a dehydrator for recovering gypsum from absorber slurry discharged from the desulfurizer;   the spray drying apparatus according to  claim 1  for spraying dehydrated filtrate from the dehydrator;   a flue gas introducing line branched from the flue gas duct for introducing part of the flue gas into the spray drying apparatus;   a flue gas supply line for returning the flue gas contributed to drying in the spray drying apparatus to the flue gas duct; and   a damper unit interposed in the flue gas introducing line and the flue gas supply line to stop the introduction and restart the returning of the flue gas, respectively.