280 



MANUFACTURE OF MILK POWDER 



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. 



. 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, F Vermicelli-machine, n hopper, o cylindrical chamber, p piston, q 

 spiral screw, q' worm-wheel, o' small holes, .r* 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 a thin film which dries rapidly. The 

 film of dried milk so formed is atomatically removed with each 

 revolution of trie 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 



