AU3531300A - Cyclone - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): VOEST-ALPINE INDUSTRIEANLAGENBAU GmbH Invention Title:

CYCLONE

The following statement is a full description of this invention, including the best method of performing it known to me/us:

IA

Cyclone The invention relates to a cyclone for separating solids particles out of a gas flow, having a separating chamber, a dust-laden-gas feed which opens into the separating chamber, a clean-gas discharge line leading away from the separating chamber, and a solids discharge line leading away from the separating chamber.

Cyclones are widely used in industry for cleaning off-gases from, for example, ore-reduction plants, sintering plants or in the cement-producing sector, and are also employed in fluidized-bed reactors for separating out fine material which has been discharged with the fluidizing gas.

o00 The important criteria for the operation of a cyclone are, firstly, the degree of separation achieved and, in addition, the energy required to operate the cyclone, which for a specific cyclone and a given 20 amount of gas and solids loading, is dependent on the pressure loss between dust-laden-gas feed and clean-gas discharge line.

Therefore, the aim of cyclone manufacturers and operators is to achieve degrees of separation which are as high as possible and pressure losses which are as low as possible. While the degree of separation which can be achieved is dependent upon a large number of factors, such as the geometry of the cyclone, the grain-size range of the solids to be separated out, and the amount and velocity of gas, for a given geometry the pressure loss can only be varied by a change in the gas velocity. However, this also changes the degree of separation, which at least in general should remain constant.

Therefore, the object of the present invention is to provide a cyclone which exhibits a considerably reduced pressure loss compared to the prior art, while the degree of separation, however, is to remain substantially constant.

2 The object which is set according to the invention is achieved by the fact that at least part of the inner surface of the separating chamber is provided with a structure which increases the wall roughness of the surface and is formed by a multiplicity of structure elements which are at short distances from one another.

Surprisingly, it has been found that this measure enables the pressure loss between dust-laden- 10 gas feed and clean-gas discharge line to be reduced by S•up to 37%, while the degree of separation remains entirely constant or decreases only to an insignificant S• extent.

Advantageously, the entire inner surface of the 15 separating chamber is provided with the structure which increases the wall roughness of the surface, so that the effect of the reduction in the pressure loss is **.particularly strongly emphasized.

According to one advantageous embodiment, in addition the inner surfaces of the dust-laden-gas feed and/or the clean-gas discharge line and/or the solids discharge line are provided with the structure. This further enhances the effect of the reduction in pressure loss.

According to a preferred embodiment, a metal sheet, which bears substantially flat against the length of the corresponding surface or is arranged at a short distance from and parallel to the corresponding surface, is provided with the structure. This embodiment is particularly simple to achieve in design terms. Such a metal sheet is easy to replace during maintenance of the cyclone.

According to a further embodiment, the base material of the corresponding inner surface is provided with the structure.

For this purpose, the individual structure elements are rolled into the base material of the corresponding component, for example the separating chamber or the metal sheet, prior to final assembly. Of 3 course, it is also possible for the structure to be applied by manufacturing steps other than rolling, for example by milling or by welding on individual structure elements.

Individual structure elements may be formed by grooves, webs, polygonal or rounded plates or platelets or depressions or recesses.

According to a further embodiment, the structure is formed by a metal mesh, i.e. the 10 individual structure elements are formed by holes and webs, i.e. the individual perforations in the metal mesh.

According to a further preferred embodiment, the structure is formed by expanded metal. Expanded D 15 metal is initially formed by a metal sheet into which rows of slots are cut or punched, the individual rows being offset from one another by approximately half a slot length. Stretching of the metal sheet imparts the typical mesh-like structure to the latter.

20 Advantageously, the dimensions of individual structure elements are selected in such a way that their dimensions with the separating chamber having a substantially circular horizontal cross section measured parallel to the surface and in the circumferential direction of the cross section of the separating chamber amount to up to 5 cm.

The novel effect of the reduction in the pressure drop brought about by the increased wall roughness occurs up to a level of 5 cm.

According to a further advantageous feature, the dimensions of individual structure elements perpendicular to the surface of the separating chamber, i.e. their height or depth, are up to 1 cm.

A cyclone according to the invention is explained in more detail below with reference to the drawing, Fig. 1.

Fig. 1 diagrammatically depicts a cyclone according to the invention in cross section, having a separating chamber i, having a dust-laden-gas feed 2 4 opening substantially tangentially into the separating chamber i, having a clean-gas discharge line 3 leading away from the separating chamber 1, and having a solids discharge line 4 leading away from the separating chamber i.

The inner surface 5 of the separating chamber is provided with a structure 6 which increases its wall roughness and in this case is formed by a metal mesh.

For the purposes of this specification it will be clearly understood that the word "comprising" means "including but not limited to", and that the word "comprises" has a corresponding meaning.

o *o o* *o

Claims (10)

1. 2. Cyclone according to Claim 1, characterized in that substantially the entire inner surface of the *.":separating chamber is provided with the structure
2. 3. Cyclone according to one of Claims 1 and 2, 20 characterized in that in addition the inner surfaces of the dust-laden-gas feed and/or the clean-gas discharge line and/or the solids discharge line (4) are provided with the structure (6)
3. 4. Cyclone according to one of Claims 1 to 3, characterized in that a metal sheet, which bears substantially flat against the length of the corresponding surface or is arranged at a short distance from and parallel to the corresponding surface, is provided with the structure (6)
4. 5. Cyclone according to one of Claims 1 to 3, characterized in that the base material of the corresponding inner surface is provided with the structure (6)
5. 6. Cyclone according to one of Claims 1 to characterized in that the structure is formed by structure elements which are made, preferably by rolling or milling, in the base material of the corresponding surface or of the metal sheet. 6
6. 7. Cyclone according to one of Claims 1 to 6, characterized in that the structure is formed by structure elements which are applied, preferably by welding, to the base material of the corresponding surface or of the metal sheet.
7. 8. Cyclone according to one of Claims 1 to 4, characterized in that the structure is formed by a metal mesh.
8. 9. Cyclone according to one of Claims 1 to 4, 10 characterized in that the structure is formed by 0 expanded metal.
9. 10. Cyclone according to one of Claims 1 to 9, in which the separating chamber has a substantially circular horizontal cross section, characterized in Q.O 15 that the dimensions of individual structure elements, e*SS measured parallel to the surface and in the circumferential direction of the cross section of the separating chamber are up to 5 cm.
10. 11. Cyclone according to one of Claims 1 to 20 characterized in that the dimensions of individual structure elements, measured perpendicular to the surface of the separating chamber are up to 1 cm. Dated this 15th day of May 2000 VOEST-ALPINE INDUSTRIEANLAGENBAU GMBH By their Patent Attorneys GRIFFITH HACK Fellows Institute of Patent and Trade Mark Attorneys of Australia