138 CONTINUOUS PROCESS EVAPORATORS 



the milk to feed the concentrator by gravity, without necessitat- 

 ing inconveniently high elevation of the forewarmer, the intake 

 is located at the bottom. 



In the front head, in close proximity to the periphery of the 

 concentrator is located the outlet of the condensed milk. Its 

 distance from the inside wall of the concentrator determines the 

 thickness of the film of condensed milk that is allowed to form 

 on the heating surface, and the amount of milk that is retained 

 in the concentrator. According to the amount of superheating 

 intended, this film may vary from J to ^ inch in thickness and 

 the amount of milk retained in the machine may vary from 6 

 to 12 quarts. 



The front head is equipped with a cover which is fastened 

 to the rim with screw bolts and which carries a spy glass through 

 which the operator may watch the process. At the conclusion 

 of the operation this cover is removed and the dasher and blades 

 are taken out, so that both the shell and the dasher can be readily 

 washed. Over the top of the concentrator extends the steam 

 line, a 3 inch pipe, with H inch laterals, supplying the steam 

 jacket, and insuring uniform distribution of heat. The steam 

 line is also equipped with regulator and steam gauge. At the 

 bottom of the concentrator is located the exhaust and regulating 

 drip valve. 



The continuous concentrator is constructed of diverse sizes 

 and capacities, the most common of these sizes are the following: 



Capacity when Boiler Capacity 



Diameter Length Concentrating required 



at the ratio H. P. 



Speed of Agitator. The proper speed of the continuous 

 concentrator is expressed in terms of rim speed, that is the 

 distance which the blades travel per minute. It has been 

 found that the rim speed which is sufficient to move the film 



