Surface aerator

摘要

In a method of and apparatus for the surface aeration of liquids an agitator rotor consisting of a disc 10 with depending blades 12 on a vertical shaft 11 is rotated at such speed and at such distance S below the quiescent level L of the liquid that the upper surface of the rotor becomes free of liquid and a standing wave or hydraulic jump is formed without the formation of spray. Air is entrained in the turbulence of the hydraulic jump and is sucked under the edge of the rotor into the low pressure zones behind the blades. Air may be further admitted to these zones by slots or holes 15 or tubes 16; it must not be allowed to enter the centre of the rotor. The area of each hole must be at least 8% of the area of the associated blade. The distance between the outer edges of the blades is preferably 0.8 to 5.0 times their width; the distance S and the height of the blades is not more than 3/10 the peripheral velocity head, and the width of the blades is not more than 1/4 the diameter of the rotor, which is rotated with a peripheral velocity of 10-20 f.p.s. An additional mixer, not depicted, may be used in the bottom of the container. The method and apparatus may be applied to the purification of sewage.