174 CONTINUOUS PROCESS EVAPORATORS 



so as to prevent the blades from running over the dry heating sur- 

 face, cutting the copper. Simultaneously with the starting of the 

 agitator the steam is turned into the jacket and then the milk 

 intake valve is opened. 



The steam pressure on the jacket is kept uniform, preferably 

 at 40 to 50 Ibs. of steam. This machine evaporates the milk at 

 atmospheric pressure. The temperature of the milk in the con- 

 centrator therefore, is practically the same as that of boiling 

 water 212 degrees F. at the sea level and varies only with the 

 altitude of the location. The ratio of concentration is regulated 

 by the rate of the mjilk inflow. As the milk inflow is increased, 

 the ratio of concentration is reduced, because the amount of 

 evaporation being constant, a smaller proportion of the water is 

 taken out of the milk. 



The density is determined by the use of the Beaume hydro- 

 meter. If the density is greater than desired, more milk is 

 allowed to flow into the machine. If the density is lower than 

 desired the inflow of milk is reduced. 



Cooling of Condensed Milk. From the discharge spout the 

 condensed milk is run over a continuous cooler from which it 

 escapes ready for packing in whatever form it is intended for. 

 The disc continuous cooler has proven very suitable for this 

 purpose. 



No subsequent superheating of the concentrated milk is 

 necessary. This product can be made of any consistency desired, 

 regardless of concentration, according to the thickness of the 

 film that is allowed to form in the concentrator, and this in turn 

 depends on the distance of the discharge from the periphery of 

 the machine. 



THE RUFF CONDENSING EVAPORATOR. 



Principle of Machine and Process. In the "Ruff Condensing 

 Evaporator," similar as in the "Continuous Concentrator/' the 

 condensing is accomplished by the film principle, but in the Ruff 

 machine the heating surface consists of one or more steam-heated, 

 revolving drums, and atmospheric air is blow r n through the milk. 

 This machine is applicable both, for continuous evaporation 

 and for condensing in batches. 



