280 



MANUFACTURE: OF MILK POWDKR 



otherwise. This subdivided product is then placed on shelves 

 or trays and dried in a chamber heated to a temperature below 

 the coagulating point of the albumen. 



Pig-. 91. The Campbell milk drier 



I. A concentrating vessel, a outlet, b valve, c hot water jacket, c 1 hot 

 water pipe, c 2 discharge of jacket, B air pipe, e connecting hose, f stand pipe, 

 g air-distributing disc, t air chamber. II. E pug mill, i cylinder, j hopper, 

 k chute, 1 horizontal shaft, m blades for stirring, m' projections for scraping 

 blades, P Vermicelli-machine, n hopper, o cylindrical chamber, p piston, q 

 spiral screw, q' worm-wheel, o' small holes, .ri endless traveling apron, s tray 

 with perforated bottom. III. G drier, t body of drier, H blower, t' flue, u 

 opening to insert trays, u' opening for removing trays, vv endless chains with 

 projections for supporting trays, w coil heater, w' pipe circulating hot water. 



In the processes of the dough-drying principle of desiccation, 

 the dried product is reduced to a marketable powder by grinding 

 it and then bolting or or sifting it. 



2. Film-Drying Processes. 



To this group belong the numerous processes in which the 

 milk, with or without previous concentration, is dried on the 

 surface of one or more steam-heated, revolving drums. The 

 milk is either picked up by the revolving drums, or it is sprayed 

 onto these drums, forming aMhin film which dries rapidly. The 

 film of dried milk so formed is atomatically removed with each 

 revolution of the drum by means of a mechanical scraper. In 

 some of the processes of the film-drying type the drying cyl- 

 inders operate in the open, under atmospheric pressure, in others 



