Spin flash dryer for producing a powder by spin flash drying

Abstract

Herein is disclosed a spin flash dryer further comprising a waste outlet arranged in a chamber bottom of the spin flash dryer for removal of a residual organic waste material from a spin flash dryer during spin flash operation and a method of operating a such spin flash dryer to remove residual organic waste material from said spin flash dryer during operation.

Claims

1. A spin flash dryer comprising: a drying chamber enclosed by at least a chamber wall and a chamber bottom; thereby defining an exterior and an interior of said drying chamber, a rotating stirrer, said rotating stirrer arranged in said drying chamber near said chamber bottom, said rotating stirrer being provided with a plurality of stirring blades; members for supply of a material to be dried, said members arranged in said chamber wall to permit passage of a material to be dried from the exterior of said drying chamber to the ulterior of said drying chamber; apertures for supply and removal of a medium for fluidization and drying and for removal of a dried product, said aperture for supply of said fluidization and drying medium, being positioned in said drying chamber wall between said chamber bottom and said aperture for removal of a dried product in said drying chamber; said spin flash dryer further comprising: a waste outlet arranged in said chamber bottom of said spin flash dryer; and wherein said waste outlet is arranged for continuous removal of residual organic waste material, which residual organic waste material cannot be spin flash dried due to a density of said residual organic waste material being higher than a lifting power of said medium for fluidization and drying of said spin flash dryer; wherein said waste outlet is a valve which forms a sluice; and wherein removal is caused by said rotating stirrer moving said residual organic waste material into said waste outlet during spin flash dryer operation upon which said residual organic waste material is removed via said waste outlet in a sluicing operation, wherein said sluice comprises a rotating arrangement of openings and closures adapted to maintain an essentially fluid tight seal between the interior of said drying chamber and the exterior of said drying chamber during operation of said sluice and said spin flash dryer.

2. A spin flash dryer according, to claim 1, wherein said waste outlet is arranged at or near the bottommost point, line, or plane of said chamber bottom.

3. A spin flash dryer according to claim 1, wherein said waste outlet is adapted for connecting to an arrangement for transporting waste material from the interior of said drying chamber to the exterior of said drying chamber.

4. A spin flash dryer according to claim 3, wherein said arrangement for transporting waste material from the interior of said drying chamber to the exterior of said drying chamber comprises a re-attachable lid for covering said waste outlet during operation of said spin flash dryer, which lid can be detached from said waste outlet during an intermission of operation of said spin flash dryer to remove any waste material accreted at or near said waste outlet on said chamber bottom manually.

5. A spin flash dryer according to claim 4, wherein said arrangement for transporting waste material is spaced below said waste outlet by an intersection, said intersection being a length of a conduit or pipe.

6. A spin flash dryer according to claim 1, wherein said chamber bottom is a conical chamber bottom which extends conically tapering upwards inside said drying chamber.

7. A spin flash dryer according to claim 1, further comprising an annular distributor for distributing said fluidization and drying medium, said annular distributor surrounding a lower region of said chamber wall, whereby said fluidization and drying medium is led into the drying chamber in an evenly manner.

8. A spin flash dryer according to claim 1, wherein the organic materials feed materials are selected from organic waste materials comprising food waste products, fruit and beet pulps, distillers' residues, waste products comprising animal blood, slaughterhouse animal waste, proteins, carbohydrates, sugars, starches, fatty waste, and/or non-caking permeates.

9. A method of removing residual organic waste material from an interior of a spin flash dryer during spin flash dryer operation, wherein removal is caused by a rotating stirrer moving said residual organic waste material into a waste outlet during spin flash dryer operation upon which, said residual organic waste material is removed via said waste outlet in a sluicing operation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: Exemplary spin flash dryer with waste outlet.

DETAILED DESCRIPTION

(2) Spin flash dryers for fluid bed drying, particularly for simultaneous drying and disintegration of a material in the form of a paste or a filter cake are commonly known.

(3) An exemplary spin flash dryer according to the invention is shown in FIG. 1, wherein a prior art spin flash dryer (100) has been mounted with a waste outlet (200) according to the invention.

(4) In FIG. 1 a spin flash dryer (100) of the prior art is shown, wherein the spin flash dryer further comprises a waste outlet (200) of the invention. Spin flash dryers (100) of the prior art are in general constructed with a drying chamber (1) enclosed by a chamber wall (2), and having a chamber bottom (3) in fixed connection therewith. A rotating stirrer (9, 10) will usually be arranged coaxially in the drying chamber (1) near its chamber bottom (3) on a shaft (7) which transfers a rotation from a rotor (6) to the stirrer (9). Usually, the stirrer (9) is provided with a plurality of stirring blades (10). The blades (10) of the stirrer (9) are normally arranged in parallel to the chamber bottom (3), but depending on function, modifications to stirrer (9) and stirrer blades (10) are known.

(5) Further the drying chamber (1) will comprise members (14, 15) for the supply of a material to be dried, apertures (5, 16) for supply (5) and removal (16) of a medium for fluidization and drying and for removal (16) of a dried product.

(6) In many spin flash dryers of the prior art, the chamber bottom (3) is a conical chamber bottom (3) which extends conically tapering upwards inside the chamber (1).

(7) Usually, the aperture for supply of the fluidization and drying medium (5) is positioned in the drying chamber wall (2) between the chamber bottom (3) and the aperture (16) for removal of a dried product in the drying chamber (1). Also customarily, an annular distributor (4) for distributing the fluidization and drying medium is surrounding the lower region of the chamber wall (2) whereby the fluidization and drying medium is led into the drying chamber (1) in an evenly manner.

(8) Usually in spin flash dryers of the prior art the blades (10) of the stirrer (9) are positioned at a relatively small distance from the chamber bottom (3). It is well known to add further stirrer elements (11, 12, 13) coaxially on the rotating shaft (7).

(9) Likewise it is commonly known in the prior art for the drying chamber (1) and the annular distributor (4) to have a stretch of common wall, which is heat insulated (17) on the side facing the distributor (4).

(10) Likewise commonly known in the prior art is for the drying chamber (1) to include at least one particle size classifier positioned inside the drying chamber (1) above the stirrer (9) but below the aperture (16) for removal of a dried product. Thereby the particle size of the dried product may advantageously be controlled. In such embodiments of the prior art comprising particle size classifiers, a plurality of apertures (16) may be comprised in the spin flash dryer of the prior art (100).

(11) To a spin flash dryer of the prior art (100), the present inventors suggest the addition of a waste outlet (200) positioned in the chamber bottom (3) of the spin flash dryer (100). A waste outlet (200) of the invention will be dimensioned according to the particular needs of the individual spin flash dryer into which it will be installed, but will often have a dimension between 30 mm to 1000 mm, usually between 100 mm to 300 mm.

(12) It is advantageous if a waste outlet (200) of the invention is positioned at or near the bottommost point, line, or plane of the chamber bottom (3). Thereby it is secured that gravitation and forces exerted by the stirrer (9) and blades (10) on the paste or filter cake mass contained in the drying chamber will drive any waste material towards and into the waste outlet (200), from where it may be removed at a time of an operator's choice. Preferentially waste material can be removed continuously during operation of the spin flash dryer.

(13) Advantageously, the waste outlet (200) is adapted for connecting to an arrangement for transporting waste material from the interior of the drying chamber (1) to the exterior of the drying chamber (1). Such an adaptation could e.g. be by a flange section on said waste outlet (200) and secured using nuts and bolts.

(14) In one embodiment of the waste outlet (200), said arrangement for transporting waste material comprises a re-attachable lid for covering the waste outlet (200) during operation of the spin flash dryer (100), which lid can be detached from the waste outlet (200) during an intermission of operation of the spin flash dryer (100) to remove any waste material accreted at or near the waste outlet (200) on the chamber bottom (3) of the spin flash dryer (100) manually.

(15) In another embodiment of the waste outlet (200), said arrangement for transporting waste material comprises a sluice adapted to permit the passage of waste material from the interior of the drying chamber (1) during operation of the spin flash dryer (100) in a sluicing operation. The sluice can e.g. be a check valve or any other type of non-return valves such as e.g. butterfly valves, double butterfly valves, or rotating valves. In a preferred embodiment the sluice comprises a revolving arrangement of openings and closures adapted to maintain an essentially fluid tight seal between the drying chamber (1) and the exterior of said drying chamber during operation of sluice and spin flash dryer. Preferably, said revolving arrangement of openings and closures is a rotating valve or sliding valve.

(16) In a further embodiment of the waste outlet (200), said arrangement for transporting waste material is spaced below said waste outlet by an intersection, said intersection e.g. being a length of a conduit or pipe. Thereby a calm zone is created below the chamber bottom which will facilitate efficient removal of waste material during operation without interfering with the drying process.

(17) Closing Comments

(18) The term comprising as used in the claims does not exclude other elements or steps. The term a or an as used in the claims does not exclude a plurality.

(19) Although the present invention has been described in detail for purpose of illustration, it is understood that such detail is solely for that purpose, and variations can be made therein by those skilled in the art without departing from the scope of the invention.