GRAIN DIAMETER CONTROL METHOD OF GRANULATED SLUDGE

PROBLEM TO BE SOLVED: To provide a grain diameter control method of granulated sludge in which grain diameter adjustment of granulated sludge is automated without spending an equipment cost to contribute to reduction of a labor cost and a stable operation.SOLUTION: There is provided the grain diameter control method of granulated sludge in a granulating and drying system 10 that dries granulated sludge which is formed by kneading dewatered sludge and recycled pellets and granulating them by a mixer 12, by a drying drum 13, uses a part of dried granulated sludge as a product, supplies granulated sludge other than the product to the mixer 12 as recycled pellets. In the method, an impulse signal is input to a recycling feeder 16 which supplies recycled pellets pooled in a recycling hopper 15 to the mixer 12 to measure a temperature change of dry air at an outlet of the drying drum 13, an average grain diameter of dried granulated sludge is estimated based on correlation between average grain diameter of dried granulated sludge and the temperature change of the of dry air at the outlet of the drying drum 13, and an amount of recycled pellets to be supplied to the mixer 12 is adjusted based on an estimated average grain diameter.SELECTED DRAWING: Figure 1 【課題】造粒汚泥の粒径調整を設備費を掛けることなく自動化して、人件費の削減及び安定操業に寄与する造粒汚泥の粒径制御方法を提供する。【解決手段】脱水汚泥とリサイクルペレットとをミキサー１２で混練して造粒した造粒汚泥を乾燥ドラム１３で乾燥させ、乾燥させた造粒汚泥の一部を製品とし、製品以外の造粒汚泥をリサイクルペレットとしてミキサー１２に供給する造粒乾燥システム１０における造粒汚泥の粒径制御方法であって、リサイクルホッパ１５に貯留されているリサイクルペレットをミキサー１２に供給するリサイクルフィーダ１６にインパルス信号を入力して乾燥ドラム１３出口における乾燥空気の温度変化を測定し、乾燥させた造粒汚泥の平均粒径と乾燥ドラム１３出口における乾燥空気の温度変化との相関関係より、乾燥させた造粒汚泥の平均粒径を推定し、推定された平均粒径に基づいてミキサー１２に供給するリサイクルペレットの量を調節する。【選択図】図１