136 CONTINUOUS PROCESS EVAPORATORS 



the upper part of the tubes at a very high speed, and is thrown 

 with great force against the ribs of the baffle plate which extends 

 across the Avhole cylindrical length of the vapor body. 



The liquid or condensed milk returns through the down- 

 take to the lower part of the steam chest where it escapes from 

 the machine. The vapor passes at both ends of the baffle plate 

 into the vapor space above and from there through the entrain- 

 ment separator for reclaiming escaping milk, and then to the 

 condenser attached to the outlet of the vapor body. 



The upper part of the tubes becomes covered with a climbing 

 film of milk. This together with the high speed of the milk in the 

 tubes (100 feet per second or more) increases the capacity of the 

 heating surface, and the small amount of milk in circulation, 

 together with the low level of the milk in the tubes, reduces the 

 possibility of foaming, confining the foam to and breaking it up 

 in the upper part of the tubes where film evaporation takes place. 



The escape of the condensed milk is continuous and the 

 degree of concentration is controlled by a valve regulating the 

 outlet. The condensed milk runs by gravity from the steam 

 chest into a reservoir located under the evaporator. In this case 

 the reservoir must be under the same vacuum as the evaporator. 

 In some cases it is recommended to have an intermediate storage 

 tank removing the condensed milk from the evaporator by a spe- 

 cially constructed steam pump. 



THE CONTINUOUS CONCENTRATOR 



The inflow of the fluid milk and the outflow of the condensed 

 milk are continuous. The milk is condensed under atmospheric 

 pressure at 212 F. A rapidly revolving agitator throws the milk 

 in a thin film against the steam-heated and continuously polished 

 periphery of a jacketed copper drum. By keeping the heating 

 surface clean and bright, and the milk rapidly moving, the power 

 of the milk to absorb and utilize heat is greatly augmented and 

 the rapidity of evaporation increased. 



