PURPOSE: To discharge ash through an ash hopper continuously to guarantee a stable boiler operation.

CONSTITUTION: An ash hopper 11 is installed in the high temperature section of a soda recovery boiler, and below the ash hopper 11 a discharger 12 is installed which has a cooling means in the lower section. Said cooling means injects water or air for cooling through a cooling piping 13 into said discharger 12 from the ceiling, side faces, and lower face of the discharger 12. With this arrangement molten ash that is received on a rotating table 14 provided in the discharger 12 is cooled and solidified by blowing water or air to it and it is discharged through an expansion joint 15, damper section 16, and discharge chute 17.