| 摘要 |
PROBLEM TO BE SOLVED: To perform spray drying operation with good accuracy by measuring the near- infrared spectrum of the spray-dried granular particles, calculating the content of each of the surfactants in the spray-dried granular particles with a prescribed arithmetic operation and controlling the spray drying conditions corresponding to the deviation of the measured/ calculated content value from a set content value of each of the surfactants, at the time of producing spray-dried granular particles contg. surfactants. SOLUTION: This production comprises: producing plural synthetic surfactants each usually used in a synthetic detergent; thereafter, evaporating water in the surfactants by spray drying to produce a granular synthetic detergent, wherein a highly concentrated slurry 14 to be dried is sprayed from the upper part of a drying column 1 through a spray nozzle 11 and concurrently, hot air is blown up from the lower part of the drying column 1 through a hot air nozzle 7; then, measuring the equivalent value to the content of each of the plural surfactants in granular particles withdrawn from the bottom of the drying column 1 by using a near-infrared spectrometer 8; and subsequently, correcting the content of each of the surfactants in the slurry corresponding to the deviation of the measured content equivalent value from a set content equivalent value of the surfactant in the spray-dried granular particles by changing the feed rate of the surfactant, while determining a new set value of the surfactant content in the slurry, corrected with respect to the deviation, by using e.g. a programmed arithmetic operation circuit.
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