To eliminate excessive addition of the incineration inhibitor when dewatered sludge is incinerated by a fluidized-bed incinerator at 840°C to 900°C, an adding amount of Ca compound acting as incineration agent is adjusted for preventing clogging, damage or the like from being generated through incineration of dust accompanied with exhaust gas at an exhaust gas flow passage, an adding amount of incineration inhibitor can be appropriately adjusted timely without generating any substantial delay in timing to eliminate any excessive addition of excessive incineration inhibitor.SOLUTION: A concentration of sulfur oxide contained in exhaust gas of a fluidized-bed incinerator either under a state in which Ca compound is not added in advance or a state in which a small amount of Ca compound is added is measured, that concentration is defined as a sulfur oxide reference concentration in advance, a concentration of sulfur oxide in the exhaust gas in the fluidized-bed incinerator is monitored when the dewatered sludge is incinerated at the fluidized-bed incinerator while Ca compound is being added, and an adding amount of incineration inhibitor agent is adjusted in response to a relative relation between the monitored sulfur oxide concentration and the sulfur oxide reference concentration.SELECTED DRAWING: Figure 1
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