Process and a spray drying apparatus for producing an agglomerated powder
AssigneeNiro Holding A/S
InventorOve E. Hansen
Life of this patent
Estimating the term…
Abstract
In a spray drying and agglomerating process carried out in a spray drying chamber (1) having a conical lower section (3), in which chamber the liquid to be spray dried is atomized into a downward central stream of drying gas and the spent drying gas is withdrawn from non-central locations (5, 11) in the upper part of the drying chamber together with entrained fine particles, m the fine particles are recycled to the drying chamber by pneumatic injection thereof from a location in the lower part of the drying chamber and in one or more directions forming an angle of 0.degree.-90.degree. to the upward center axis of the chamber. An apparatus suitable for carrying out the process has the capability of performing the separation and recycling of the fine particles as specified.
Claims24
A process for producing an agglomerated powder by spray drying a liquid in a drying chamber of which the lower part is formed by a conical downward tapering section, including the steps of atomizing said liquid in the upper part of the chamber into at least one downward first stream of drying gas to produce particles, withdrawing a stream of spent drying gas from at least one non-central location in the upper part of the drying chamber together with entrained fine powder particles, thereby creating a drying gas flow having an outward and upward turning portion in the conical chamber section, collecting said fine powder particles from the thus withdrawn stream of spent drying gas, and recycling them to the drying chamber, and recovering an agglomerated powder product from the bottom of the chamber, characterized in that the recycling of said fine particles to the drying chamber is performed by pneumatic injection thereof from a location in the lower part of the drying chamber and in one or more directions forming an angle of 0.degree.-90.degree. to the upward center axis of the chamber, to utilize said outward and upward turning portion of the drying gas flow to introduce the fine particles evenly in a horizontal, annular zone near the wall of the conical section of the chamber.
A spray drying apparatus having a drying chamber (1), the lower part of which is formed by a conical downward tapering section (3), means (4) for atomizing a liquid into an atomizing zone in the upper part of the chamber, drying gas distributing means (6) for directing at least one first stream of drying gas downward around the atomizing means, means for withdrawing an agglomerated powder from the bottom of the chamber, outlet means (11) in the top of the chamber for withdrawing a stream of spent drying gas and entrained fine particles, and means for collecting said fine particles (12,13) and reintroduction thereof into the drying chamber, characterized in that said means for reintroducing said fine particles into the chamber comprises means (14) for pneumatic injection of the fine particles in the lower part of the drying chamber and in one or more directions forming an angle of 0.degree.-90.degree. C. to the upward center axis of the chamber (1) to introduce said fine particles evenly in a horizontal annular zone (A) near the wall of the conical section (3) of the chamber by utilizing an outward and upward drying gas flow existing in the lower part of the drying chamber during the operation of the apparatus.
Dependencies are inferred from the claim text.