WO1997046473A1

WO1997046473A1 - Horizontal fluid bed for powder transportation and distribution

Info

Publication number: WO1997046473A1
Application number: PCT/NO1997/000143
Authority: WO
Inventors: Odd E. BJARNÖ
Original assignee: ABB Flaekt AB; Flaekt AB
Current assignee: ABB Technology FLB AB
Priority date: 1996-06-06
Filing date: 1997-06-05
Publication date: 1997-12-11
Anticipated expiration: 1998-12-06
Also published as: NO962365D0; AR007501A1; AU3109497A; NO962365L; NO307042B1

Abstract

Horizontal fluid bed for transportation and distribution of powder, the bed thereby comprising several connected fluid bed sections, each section comprising underneath an air manifold having air supply and having an upper limitation in the form of a fabric, the fabric providing the bottom in the transportation channel of the section and that at least some of the sections comprising a dosing aperture (3) for discharge of powder.

Description

Horizontal fluid bed for powder transportation and distribution

The present invention is related to a horizontal fluid bed for transportation and distribution of powder.

Transportation and distribution of aluminium oxide to every single one of a number of filter devices in a plant for dry cleaning and fluorine recovery for the aluminium industry normally is performed by the use of different types of distribution boxes to distribute aluminium oxide and thereafter to transport the single portions to separate fluidized gutters or through fluidized gutters comprising several chambers. These systems comprise many different parts and a great number auxiliary devices for the supply of fluidizing air, exhaust fluidizing air through exhaust pipes and supports.

Fluidized gutters as described above must have an inclination of approximately 4-6° to provide a secure transpor¬ tation. For large plants this means a height difference between the end points of the gutter of several meters which again means that admittance at several levels must be provided to ensure inspection and maintenance.

The reliability of the systems may be influenced negativ¬ ely if large and heavy particles are not removed before they are brought into the system, such as by means of sieves. Therefore some plants have flow controllers at each single injection point.

Object for the present invention is to avoid the above described disadvantages by known embodiments. This is achieved with the device according to the present invention as defined with the features stated in the claims.

As air for the fluid bed is supplied under controlled conditions in each section, it is ensured that the fluid bed as such is maintained homogeneous along its entire length. As some of the stations are connected with each other by flanges where the fabric through which the air is brought into the fluid bed, is bent in junctions between two sections, there will exist a minimum area without supply of air. This area is so little that there will not be built up a not fluidized mass between the sections. As each section ensures maintenance of the fluid bed, a minimum inclination of the powder in the fluid bed is necessary to achieve transportation of the powder. For example may the inclination of the powder in the fluid bed be as little as some few millimetres on several meters of length. This provides significant advantages for the building of the plant and savings in the height as well as inspection of the plant during operation.

The drawing discloses in figure 1 a side view of a section of a fluid bed according to the invention, figure 2 discloses a ground view of the section in figure 1, figure 3 discloses a section III-III in figure 3, figure discloses a section IV-IV in figure 3, figure 5 discloses a side view of a fluid bed comprising several sections, figure 6 discloses a ground view of the fluid bed in figure 5, figure 7 discloses a section VII-V I in figure

1 and figure 8 discloses a section through a joint between sections.

As figures 5 and 6 disclose, the fluid bed comprises several connected sections as disclosed in figure 1. The fluid bed comprises vertical slots at each discharging point. Of practical reasons a bed with large capacity as a cross section of 200 x 500 mm. This bed is normally filled with aluminium oxide up to approximately 300 mm above the fluidizing fabric 1 along the entire length of the bed which typically may be between 10 and 50 m, and which provides a fluidized transportation bed.

Normally the aluminium oxide is brought in at one end of the bed and transported along the bed. By specific intervals the aluminium oxide is discharged through vertical slots and down to the feeding points. To avoid separate adjustments for uniform flow at each slot it is important that height differences between the fluidized aluminium oxide in the bed approximately is zero. This is achieved with a structure having very low friction.

The bed very easily may be fluidized and comprises flanges

2 for connection of sections as well as gables at the ends. All walls are vertical and the cross section of the bed is large enough to provide low horizontal transportation speed. The fluidizing speed is maintained high to make it possible that also coarse and heavy particles may be fluidized and mixed into the aluminium oxide thereby ensuring that these leave the bed together with the aluminium oxide. The advantages achieved with the invention are especially a reliable and simple structure claiming little space. Furthermore, the claims for necessary control and calibration of the single points are low. Dead points were heavy particles may fall out, especially also by the flanges, are avoided. Further a proportional distribution of the aluminium oxide at each point is achieved independently of the total flow. Due to the fact that airing is performed together with the aluminium oxide, the need for separate airing points is illuminated.

Furthermore it is an advantage that a possible discharging of the bed may be performed within few minutes without special tools.

As disclosed in figure 5 the plant is comprising several sections as disclosed in figure 1. The single sections are connected to each other by flanges 2. Each section comprises an outlet for the powder in the shape of a vertical slot opening 3 in the side of the section. Of the amount of powder flowing by, a part therefore will come through the slot 3 and be brought further to the independent station for further treatment.

The independent sections are connected to each other with the flanges 2 and the fabric 1 is bent in the joints, substantially abutting against the fabric of the adjacent section. With such a design it is achieved that the area between the two sections which is not provided with supply of air through the fabric, is minimum and it is therefore avoided that powder is collected on such places which is significant for the functioning and mainte¬ nance of the plant.

Claims

P a t e n t C l a i m s

1. Horizontal fluid bed for transportation and distribu¬ tion of powder, CHARACTERIZED IN the bed comprising several connected fluid bed sections, each section comprising underneath an air manifold having air supply and having an upper limitation in the form of a fabric, the fabric providing the bottom in the transportation channel of the section and that at least some of the sections comprising a dozing aperture (3) for discharge of powder.

2. Fluid bed according to previous claim, CHARACTERIZED IN the dozing aperture being a vertical slot leading out to a dozing channel for the dozed amount of powder, and that the dozing channel being able to assume the amount of air brought into the air manifold.

3. Fluid bed according to previous claims, CHARACTERIZED IN the individual sections being connected with each other by flanges (2) and that the fabric (1) being bent against an acute end surface on each section, the fabric thereby being connected with clamping devices (4, 5).