Process and an apparatus for producing a powdered product by spin flash drying
AssigneeAPV Anhydro AS
InventorJens Getler
Life of this patent
Estimating the term…
Abstract
A process and an apparatus for drying of a material in the form of a paste or a filter cake in a spin flash dryer. Particles are separated by a classifier (6) in the chamber (1) in such a way that oversize fraction is withheld in the chamber (1) and the desired fraction is removed (3, 9). A possible undesired undersize fraction is strained off and recycled (4, 10, 11) externally back to the dryer chamber (1). The spent drying gas is recycled to the dryer chamber (1). In either, the energy in the spent drying gas may be made use of in a heat exchanger and there is no or only little emission to the environment. Products preferably dried according to the invention are fruit and beet pulps, destillers residues, pesticides, pigments, dyes, ceramics, active coal, sludge and zeolites.
Claims21
A process for producing a powder by spin flash drying, thereby drying a paste or a filter cake comprising the steps of,
- feeding the material to be dried to a dryer chamber (1),
- contacting said material with a stream of drying gas to obtain dry particles,
- adjusting the amount of introduced material with the amount and drying capacity of introduced drying gas thereby controlling to a desired moisture content and size of the particles leaving the dryer chamber (1),
- subjecting said particles to a size classification into at least two fractions in a classifier (6),
- which first fraction comprises particles with the predetermined particle size distribution, which is withdrawn as product, suspended in a first exit gas stream,
- and which second undersize fraction is withdrawn from the classifier (6) as an entrained suspension in a second exit gas stream and is returned to the dryer chamber (1) as solid particles.
An apparatus comprising,
- a spin flash dryer with a vertical, cylindrical dryer chamber (1), having a rotating coaxial placed stirrer, with a variable speed drive screw feeder (5) and with apertures (2) for supply of hot drying gas and for the removal of the spent drying gas and removal of the dried material,
- a first classifier means (7) in the upper part of the dryer chamber (1),
- a second classifier means (8) in the upper part of the dryer chamber (1),
- means (9) for separating suspended desired particles from drying gas,
- means (10, 11) for separating and recycling undersize particles to the dryer chamber (1).
Dependencies are inferred from the claim text.