A process for producing by spray powder from liquids of the type which by spray drying tend to give a voluminous powder, and the nebulizer for use in the practice of the method.

摘要

1439540 Spray drying and de-gassing liquids; spray-producers NIRO ATOMIZER AB 20 Aug 1973 [29 Aug 1972] 39361/73 Headings B1B, B1M and B2F Milk or similar liquid is spray dried using a rotating atomizer wheel by heating the liquid, prior to atomization into a drying chamber, to such a temperature that degasification occurs inside the atomizer wheel and removing the gas so released before atomizing the liquid. Heating may be by mixing with steam either before the liquid enters the atomizer wheel or inside the wheel. The drying chamber may be under reduced pressure. The atomizer comprises a wheel 102 which has two sets of ejection apertures 106, 107 in a mutually axially spaced relationship, each set communicating with its own of two annular supply compartments 104, 105, one supply compartment 104 only communicating with a feed pipe 156 for liquid to be spray dried and the two supply compartments 104, 105 intercommunicating by means of at least one aperture 150. The two sets of ejection apertures are so constructed that the upper set 107 has a greater fan effect than the lower set 106. The resultant pressure differential serves to remove the gas outgassed from the liquid in chamber 104 via aperture(s) 150 and chamber 105. As shown in Fig. 2 the liquid is heated by steam supplied by pipe 154 through annular duct 165, chambers 104, 105, aperture 150 and liquid supply duct 164 all being annular and concentric with shaft 101. The upper surface of the wheel 102 carries vanes 151 and is supplied with air via pipe 162 to prevent particles being drawn in to the space between the wheel and its support. In another embodiment (Fig. 1, not shown) the liquid and steam are mixed in a chamber 18 in the support for the wheel before delivery to the lower supply compartment 4 in the wheel.