Some Factors Influencing the Capacity of the Atmospheric Drum Drier

Abstract

Summary Some of the possible factors responsible for variations in the capacity of atmospheric drum driers are suggested. A standardized method of procedure was set forth for the operation of the drier. The influence on the capacity of the drier on variations from this procedure are reported. Under standardized or normal operation it was stated that the capacity of the drier was from 58 to 60 pounds per hour. Drying of cold milk (50 to 60° F.) resulted in a decrease of 8 per cent in the capacity of the machine. By preheating skimmilk to 185° F., an increase in the capacity of the machine of 18 per cent was secured. It was noted that 26 to 28 per cent more dry skimmilk resulted per hour when skimmilk was applied to the drums at 180 to 185° F. than when skimmilk was applied on the machine in a cold (50 to 60° F.) state. The level at which the skimmilk is maintained over the drums was shown to materially affect the capacity of the drier. In one instance the capacity of the machine was reduced to 32 pounds per hour when a low level was maintained, and in another, when a high level was used, there was a yield of 72 pounds of dry skimmilk per hour, a difference of 40 pounds per hour. The influence on capacity of the steam pressure in the drums and the speed of the machine was studied. With an increase in speed of drums to 36 r. p. m. and an increase in steam pressure in the drums to 85 pounds, the capacity of the machine was 85 pounds of dry skimmilk per hour. Regardless of the temperature of the milk when applied to the drums, the increased speed and steam pressure resulted in increased capacity of the machine. The greatest capacity was secured, however, when the temperature of the milk was applied at the higher temperature (185° F.) using a high speed of machine and high (85 pounds) steam pressure. The most marked influence on the capacity of the drier was noted when concentrated skimmilk containing 30 per cent solids was dried. When cold (40° F.) concentrated skimmilk was applied to the drums operated at 34 r. p. m. a capacity of 70.2 pounds of dry skimmilk per hour resulted. By reducing the speed of the machine to 20 r. p. m. and applying milk at 180° F. to the drums, a capacity of but 73.2 pounds of dry skimmilk resulted. By using the same steam pressure, increased speed of drums up to 36 r. p. m., and applying concentrated milk at 180° F., the capacity of the machine was increased to 130 pounds per hour, or 116 per cent increase over that secured under the standardized method adopted. Though some variation was observed in the moisture content of dry milks produced on the drum drier, it was not possible to correlate variations in moisture of dry milk with the rate at which dry milk was produced from the dryer. With milk of uniform freshness it was evident that variance of the capacity of the drier had no effect on the amount of dispersion of dry milk when reconstituted with water.