Pressure and Temperature.
—To obtain the temperature above mentioned a pressure of 150 pounds should be carried, and late practice introduces a superheater for reheating the steam to insure high temperature by adding 100° to 150° F. to the steam temperature.
FIG. 156.—SECTION OF BOTTOM OF DEODORIZING TANK.
Bleaching Process.
—As soon as the oil is deodorized it is drawn off and allowed to cool. It is pumped into the treating kettle, or what is known in refineries as the “dirt” kettle. There it is brought up to a temperature of 160° F., when the fullers earth is added, generally using from one to two percent of earth with this bleach, following an agitation of about ten minutes. It should then be pumped through the filter press into the receiving tank, where it is held until used. After going through this process the oil is known to the trade as “water white.”
FIG. 157.—SECTION THROUGH EXHAUST HOOD OF DEODORIZING TANK.
Mixing.
—Refined tallow or oleo stearine melted and clarified by pumping through a filter press without the use of fullers earth is added to the cotton seed oil so prepared, and the mixed substance, containing proportions previously described, are ready for passing over the cooling roll.