THE PREPARATION OF CORN" OIL. 23 



operations in a refinery like the one under consideration is such that 

 the two workmen have ample time to deodorize the oil in two batches. 



The principle involved in deodorization is that of blowing live steam 

 through the oil for several hours at temperatures above 400° F. under 

 a very high vacuum. For the most effective results the steam must 

 be brought into very intimate contact with the oil, which is accom- 

 plished by introducing the steam into the deodorizer through numer- 

 ous minute perforations in a series of pipes emanating from a header. 



In the industrial application of this principle several different 

 procedures are followed. In some plants the oil is heated by closed 

 steam coils to as high a temperature as is possible with the regular 

 factory boiler steam and is then blown, either with some of the 

 same steam or with a separate line of superheated steam. Others 

 heat the oil with ordinary factory steam or with superheated steam 

 in closed coils until nearly the required temperature is reached and 

 then turn in the open steam, likewise superheated. The tendency 

 seems to be to use open steam at as low a pressure as is practicable. 



The great difficulty in heating the oil by superheated steam is that 

 it is practically impossible to attain the desired temperature by such 

 means. Since it is entirely feasible to carry superheated steam at a 

 temperature of 600° F. it would appear to be a simple matter to use 

 it to maintain oil at a temperature of 400° to 440° F. As a matter 

 of fact, however, it is almost impossible to accomplish this. Con- 

 sequently, the oil is often heated in a direct-fired furnace, designed 

 very much like a direct-fired ordinary steam superheater, substituting, 

 however, the oil stream for that of the steam. Any desired temper- 

 ature can be attained by such an arrangement, the control is good, 

 and the performance satisfactory. 



It has been calculated that the consumption of coal in a direct- 

 heat deodorizer is about one-fifth of that used in one heated by super- 

 heated steam, which, in a batch of the above size (25,000 pounds), 

 amounts to more than one-third of a cent per pound of oil. Of course 

 if other uses can be found for the heat of the steam after it leaves the 

 coils of the deodorizer there must be a credit entered against the coal 

 charged to deodorization. But in a small refinery the intermittent 

 character of this additional use precludes any serious attempt at its 

 utilization. Expedition and skill are required in handling such direct- 

 fired equipment, and great care must be exercised or a batch of oil 

 will be burned. -The pumping capacity for forcing the oil through 

 the heater must be ample in order to prevent scorching, and there 

 must be protection against mishap, such as stoppage of flow, since 

 this would result in ruining the entire batch. 



In a large refinery it may be more practicable to locate the oil 

 heater near the boiler room of the plant, so that one crew of firemen 

 and the coal and ash handling equipment can take care of all the fires; 



