| 摘要 |
In a spray-evaporating process, the drying gas is sent through the drying chamber with so great an axial velocity of flow (V metres per sec.) that the expression <FORM:0712746/III/1> is at least equal to 5, where ti is the inlet temperature and tu is the outlet temperature of the drying gas (in DEG C.) and G is the quantity of water (kgs. per sec.). The velocity is greater than that previously employed, enabling the dimensions of the drying chamber to be reduced and effecting economies in heat. In an example ti is 160 DEG C., tu is 80 DEG C. and V is 0.67 metres/sec. evaporated per unit of time. The diameter of the chamber is 2.5 metres and its <PICT:0712746/III/1> height 3 metres whereby a particle is in the chamber for 4.5 secs. As described milk is introduced into a drying chamber 1 through an atomiser 4 driven by a motor in a housing 5. Drying gas is supplied through a chamber 7 communicating with the drying chamber 1 through an annular opening 8 provided with adjustable guide blades 9 adapted to be turned about vertical axes whereby the gas may be directed more or less inwardly towards the central portion of the drying chamber 1. The gas flows through the chamber in helical paths and escapes through an outlet 11 also having guide blades 12 which are adjustable into different angular positions for separating dried solids from gases. Dried particles are removed through apertures 13 in the bottom of the drying chamber by a rotating scraper 14.
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