Urea hydrolysis apparatus and control method thereof

A can suppress sticking of by-products upon hydrolysis of the urea, can also prevent a sudden drop in the surface temperature of the hydrolysis catalyst layer during excessive urea water supply, the discharge amount of gas from the ammonia spray nozzle provide a method which can be controlled constant. A by contacting the urea water U in a heating atmosphere and hydrolysis catalyst 1 to produce ammonia A, urea hydrolysis apparatus for reducing NOx in the combustion exhaust gas is blown into the combustion flue gas in the furnace 10 or the flue in a reactor 2 having a hydrolysis catalyst layer 1, a urea water supply line 3, the urea water supply pump 5, a urea water spray nozzle 6, the heated air supply line 7 for supplying heating air a ', blower 8, the heated air heater 9, the ammonia supply line 11, the ammonia spray nozzle 12, and an air bypass line 13, like the surface temperature of the hydrolysis catalyst layer 1 upon hydrolysis of the urea is 200 ° C. or higher operation of the urea hydrolysis apparatus for controlling the output of the air flow and the hot air heater 9 of the blower 8 in. .FIELD 1