To surely prevent the occurrence of white smoke by suppressing the humidity of the air discharged to the atmosphere, according to the atmospheric conditions.

This vessel is provided with a shutoff member 8 free of ascending and descending above a filler block. When outside air temperature is low, the shutoff member 8 is lowered, and the distribution to the circulation space 32a right below the shutoff member 8 of hot water sprinkled from sprinkler holes 12 is shut off. The hot water is distributed only to other circulation space 32b, and the air with low humidity which has passed the circulation space 32a and the air with high humidity which has passed the circulation space 32b are mixed, and is discharged to the atmosphere.