WO2015114135A1 - Annular cascade classifier with downstream rod-cage classifier - Google Patents

Abstract

An installation (1) for classifying feedstock (10), comprising at least one cascade classifier (2) for classifying feedstock (10) into a coarse-grade material fraction of coarse-grade material (14) and a first middle-grade material fraction of first middle-grade material (13) and at least one rod-cage classifier (3), which is arranged downstream of the at least one cascade classifier (2) in the direction of classifying air and is intended for separating the first middle-grade material (13) into a fine-grade material fraction of fine-grade material (20) and a second middle-grade material fraction of second middle-grade material (21). The at least one cascade classifier (2) is of an annular design, wherein classifying cascades (5) are arranged in the manner of a spiral staircase in a hollow cylinder (6), bounded by an inner cylinder and by an outer cylinder. This has the result of increasing the classifying performance while at the same time reducing the amount of space required.

Description

 Ring-shaped cascade classifier with downstream rod basket sifter

The invention relates to a system for sifting feedstock, comprising at least one cascade sifter for sifting a feedstock into a coarse material fraction of coarse material and a first middlefork fraction from first middlecrop, at least one rodcassifier arranged downstream of the at least one cascade sifter in view airflow for separating the first middleware into one Fines from fine material and a second middle fraction from second medium.

For the sighting of granular material, such as in the production of raw meal for cement production or for the production of fine cement clinker meal for the production of cement flour, it is known to subject the granular material in a continuous grinding plant a repeated crushing process and the circulating Good by a sifter or to remove fines from successive classifiers. In the process, the still granular material remains in circulation until it corresponds to the visual process through comminution and is screened.

The type of switching of different classifiers and the type of comminution have a great influence on the grinding result. The grinding result is characterized by the fineness, but above all by the particle size distribution. There are grinding results with a broad grain distribution and grinding results with a very narrow particle size distribution. In the production of cement, the grain size itself and also the particle size distribution has a great influence on the achievable cement strength. This is usually explained by the fact that ner with a smaller diameter have a larger surface area in relation to the volume and also that the grains can take an ideal spherical packing at a certain particle size distribution. The particle size distribution depends on a variety of parameters and a plant produces different grinding results for different ores, minerals or cement clinker. The skilled person is endeavoring to select by empirical observation, the ideal interconnection of classifiers and crushing devices with different ways of circulating material to get to a desired grain size distribution of the material to be ground.

In addition to the grinding result, the space and the volume of a sighting system for use as a unit of a grinding plant is of increased interest. The person skilled in the art endeavors here to design systems that are as small as possible in order to optimize the energy-intensive circulation of the ground material as far as possible. The necessary height difference to be overcome within the plant is the cause of the required lifting energy of the ground material in circulation. In addition to the pure grinding energy, the lifting energy for the grinding material in circulation is the main reason for the high energy consumption of a grinding plant. With grinding capacities of up to 3,000 l per day, each saved height meter means a considerable saving in energy that can not be recycled back into the process, which is necessary for circulating transport.

A small, compact system also makes it possible to retrofit into existing systems in which, due to structural reasons, only a small amount of space is available at the desired location to set up the system.

European Patent EP 1 287 91 1 B1 discloses a cascade classifier whose visual floods are designed to be adjustable in order to allow the visual gas velocity for setting the visual result.

European Patent Specification EP 1 506 058 B1 teaches a classifying plant for use in the cement industry, in which a roller press is used for crushing is arranged vertically between the output device of a rod basket sifter and the entry opening of a cascade sifter. In this case, the straightened material of the cascade classifier below the roller press is conveyed pneumatically from below the roller press into the rod basket sifter arranged above the roller press.

International patent application WO2008 / 022778 A2 discloses a cascade classifier consisting of nested conical rings, wherein the cascade classifier has a cylindrical symmetry. This cascade classifier offers a comparatively large number of cascades or visual floods in a confined space over which the material to be cultivated can roll and thereby deagglomerate.

German Offenlegungsschrift DE 10 2008 018 488 A1 discloses a sighting system in which an overhead, central rod cage sifter is supported by lateral, pneumatic ascending channels and offers a space for the accommodation of roller presses. The cascade classifiers are arranged for deagglomerating pressed slugs from the roller presses below the roller presses and form with the one common rod basket sifter a system similar to that taught in the European patent specification EP 1 506 058 B1.

A sighting system with several roller presses and a central riser shaft is disclosed in WO2009 / 068465 A1. On the central riser shaft sits a central rod basket sifter, which is surrounded by dedusting cyclones. Also in this classifier several roller presses are arranged around the central riser shaft, with several cascade classifiers feeding their fines into the central riser shaft, which is further spotted in the overhead rod sifter.

The object of the invention is to provide a compact system for sifting granular material available, which allows for short transport paths different circuits of present in the plant classifiers. The object underlying the invention is achieved in that the at least one cascade classifier is designed annular, wherein visual cascades are arranged helically in a hollow cylinder limited by an inner cylinder and an outer cylinder. Further advantageous embodiments are specified in the subclaims to claim 1.

According to the invention, it is provided that a cascade classifier is arranged in a hollow cylinder limited by an inner cylinder and by an outer cylinder, which is bounded from the inner cylinder to the inside and from the outer cylinder to the outside. Instead of constructing the Cascade classifier in a typical V-shape, with one leg of the V being the visual cascades and the opposite leg the visual floods is provided according to the invention, the vision cascades substantially helical, like a cylindrical helix within the walls of two nested cylinders to arrange. Since the cavity between two cylinders arranged inside one another can not be subdivided into two spaces by a helical shape, it is important that the two spaces which are separated from one another by the helically arranged visual cascades still have an additional wall between the beginning of the helically arranged visual cascades and the end of the helically arranged visual cascades is present, which prevents a Sichtluftkurzschluss. Because the pressure drop of the classifying air as it flows through the air gaps between the individual view cascades is greater than a pressure drop in the flow of the classifying air wendeiförmig along the boundary of the cascades view and at the end of the view cascades in the upper annulus.

The idea of the invention is to geometrically adapt the task of the sighted feed material of the cascade sifter to an annular task of a bar cage sorter. Due to the annular task of the medium from the feed material through the annular cascade classifier onto the rod basket sifter, this also changes its known mode of operation. In known Stabkorbsichtern the average is usually at one point in tangential Added direction outer annular space, which forms a cyclonic, spiral flow around the rotating rod basket. In this case, it is important to optimize the flow of the medium, so that the entire surface of the rotating bar basket is uniformly flowed by the good to be seen. Due to the annular task of the medium, the rod cage sifter is uniformly flowed over the entire circumference, except for differences in flow due to the different vertical distance of the view cascades from the rod basket. As a result, the visual performance, the throughput, the rod basket is larger, because the entire Stabkorboberfläche is flown and not only part of the circumference of the rotating rod basket.

Therefore, according to a preferred embodiment of the invention, it is provided that the hollow cylinder is limited by an inner cylinder and an outer cylinder by the spiral staircase arranged view cascades and a partition in two helically interlocking, superimposed annular spaces is divided, wherein the feed material by a corresponding to the arranged outer wall disposed feeding device in an upper annulus, and wherein classifying air passes through a corresponding arranged on the outer wall feeder in a lower annulus, for viewing the view air flows through gaps between the spiral staircase arranged cascades and thereby easily entrains suspendable medium in the classifying air ,

In principle, it is sufficient if the diameter of the annular cascade sensor and the outer task of the bar basket are approximately the same. With different diameters, it is possible to adapt the two diameters to one another by means of a cone. But it is preferred if the inner and outer diameter and thus the gap width of the hollow cylinder limited by an inner cylinder and an outer cylinder with the inner and outer diameter and thus the gap width of an annular material task for the rod basket sifter corresponds. This eliminates a cone-shaped adjustment between the annular cascade classifier and the annular task to the bar basket, whereby the pressure drop of the classifying air is reduced and the flow is ensured evenly around the circumference of the bar basket.

In order to be able to use the plant in a Kreislaufmahlanlage, a discharge device for coarse material at the lower end of the upper annulus is arranged through which rolls not suspendable in the classifying air coarse material and passes back to a crushing device.

In the plant for sifting different Sichtgutfraktionen are formed. From the feed material, the first coarse material is discharged through the cascade classifier at the end of the cascade classifier. The sighted gui of the cascade sifter is fed as the first medium fraction to the rod basket sifter. This rod basket sifter screens a fine material fraction from the first medium, which is discharged from the system for sifting with the classifying air. The fraction falling back from the rod cage sifter as the second middle fraction can now be eliminated from the plant for sifting or run in a circle in the plant.

In a first preferred configuration, provision is made for the rod cage sifter to have an inner, annular annular gap as a discharge device for the second middle fraction, the second middle fraction flowing out of the system through a discharge device and flowing outside the system to the feedstock or to a comminuting device.

In a second preferred configuration, it is provided that the rod basket sifter has an inner, annular annular gap as a discharge device for the second middle fraction, the second middle fraction flowing through a discharge device into the upper annulus of the cascade sifter and flowing within the system to the feedstock.

There is space in the interior of the sifting system for a drive of the rod cage sensor, so that in a preferred embodiment of the invention a drive for the rod basket in the inner, free of Umlaufgut cylinder of the annular cascade classifier is arranged.

The fines discharge of the bar basket can be directed upwards, so that the fines discharge with the Sichtkluft flows upward away. Preferably, it is accordingly provided that a fine material discharge device is arranged above the rod basket sifter.

Since the entry of the classifying air by means of visual cascades of the classifying air arranged in a spiral staircase with the first medium of the cascade classifier imposes a helical flow direction, it is advantageous if the angle of the plane of the class of cascades is adjustable. In addition, it is advantageous if the number of revolutions of the rod cage classifier is adjustable independently of the air pressure of the classifying air in order to meet the different flow requirements of the various combined classifiers in the sighting system.

The invention will be explained in more detail with reference to the following figures. It shows:

Fig. 1 is a sketch of a broken view of an inventive

 Plant for sifting,

2a shows a sketch to illustrate the annular spaces of the cascade classifier,

FIG. 2b shows the sketch from FIG. 2a with the annular spaces of the cascade classifier drawn apart vertically and the tracing air flows drawn

FIG. 1 shows a plant 1 according to the invention for sifting in a partially open view. Annex 1 for sifting consists of a combination of two different classifiers, wherein a lower, annular cascade classifier 2 and an upper rod basket classifier 3 are interconnected via a common cylindrical jacket surface 4. The cascade classifier 2 has spiral-like arranged viewing cascades 5, which are arranged in a hollow cylinder 6, wherein in the context of this description The helical staircases arranged view cascades 5 divide the hollow cylinder 6 in an upper annular space 7 and in a lower annular space 8. To the two annular spaces, namely upper annular space 7 and lower annular space 8 completely an additional wall 9 is provided for sifting of feed material 10, this is fed via a feeder 1 1 in the upper annular space 7, where the feed material 10 falls over the helical staircase arranged view cascade 5 and thereby deagglomerated, if it is in the The coarse material 10 experiences through the gaps 5a between the sight cascade 5 a significant Sichtluftquerströmung 12, wherein the Sichtluft entrains a first Mittelgut 13 as the first Mittelgutfraktion from the feed material 10 via a pneumatic transport remaining coarse t 14 is removed as coarse material fraction via a discharge device 15 at a lower end 16 of the upper annulus 7 from the plant 1 for sifting again and if the plant 1 is for sifting in a Kreislaufmahlanlage, returned to the grinding circuit. The entrained with the classifying air Mittelgutfraktion is transported with the classifying air upwards and there is approximately uniformly distributed around the circumference on the circumference 17 of a rotating rod basket 18, wherein the classifying air through the regularly distributed along the circumference 17 turbo elements 19 of the rod basket 18 flows through and while a fines 20 entrains. In contrast, from the first Mittelgutfraktion a second medium 21 as the second Mittelgutfraktion that does not flow through the rotating rod basket 18, dropped into an inner hollow cylinder 22, where the second medium 21 can take different paths, depending on the desired system configuration. In a first system configuration, the second medium 21 is collected in the inner hollow cylinder 22 and fed back to the upper annular space 7. In order to avoid that an internal stream from a second medium fraction is accumulated in the plant, it is provided in a further configuration of the plant 1 that the second middle fraction of the hollow cylinder 22 via a Austragsvorrich- tion, which is not shown here, through the upper annular space 7 or through the lower annulus 8 through out of the plant 1 for sifting out, this discharged second average fraction is combined with the coarse material 14 and fed into the circulation of a crushing device, not shown, before after being passed through the comminution device, it is fed again as feed material 10 of the system 1 for sifting. The fines 20 leaves the inner rod basket 18 upwards via a discharge device 23, where the fines 20 leave the plant 1 for sighting with the classifying air.

As in the interior of the two annular spaces, upper annular space 7 and lower annular space 8, provides space for a drive of the rod basket 18, an electric motor 24 with a gear 25 is arranged there.

In order to illustrate the geometry of the two annular spaces, upper annular space 7 and lower annular space 8, the approximate volume of the two annular spaces 7, 8 is shown in the figures FIG. 2a and FIG. 2b in a sketch, the two annular spaces 7 in FIG. 8 are shown as they are interleaved in Appendix 1 for sifting. As indicated by the downward arrow 26 in FIG. 2a, the lower annulus 8 is moved downwards for clarity in FIG. 2b. The lower annular space 8 has a helical structure, wherein visual floods 5 are arranged helically along the helix 27 in the hollow cylinder 6. Through an existing between two visual floods 5 air gap 28 classifying air 29 flows into the upper annular space 7, which entrains a first middle goods 13 from the feed material 10. The first middling material 13 is carried approximately uniformly with the classifying air 29 up to the upper edge of the upper annular space 7, where it is approximately evenly distributed around the circumference and impinges on the rotating rod basket 18, which is no longer shown in FIGS. 2a and 2b.

The arrangement according to the invention leads to a different flow behavior of the visible air stream which flows into the rod basket sifter 3. In known Stabkorbsichtern the air is blown in tangentially, where the Sichtluft forms a spiral flow in the plane and flows with a half, maybe a quarter of a turn into the rotating rod basket. As a result of the tangential inflow, larger particles are thrown outward from the visual material entrained with the classifying air and less large particles follow the classifying air through the rotating rod basket. In the present rod basket sifter 3, the classifying air 29 with a tangential and with an axial direction component distributed from below to the periphery on the rod basket 18 give up. The tangential component also leads to the prospect of the coarser material. Due to the approximately uniformly distributed around the circumference of classifying air 29 with Sichtgut 13, the performance of the rod basket sifter 3 is increased because the entire surface of the rod basket 18 is uniformly flowed and not just a part thereof. At the same time increased performance due to the better surface use and the space requirement of the plant 1 for sifting is smaller. The lower space requirement in turn has the consequence that the energy-consuming transport cost of the classifying air stream 29 is less with the visual material suspended therein and therefore increases the performance of this system compared to conventional configurations by the same number of causes simultaneously.

E N G L I S H E N C 1 S T E

Annex 16 lower end

Cascade classifier 17 Scope

 Stabkorbsichter 18 Stabkorb

cylindrical surface 19 Turboelement

Sight cascade 20 fines

 Air gap 21 second medium

Hollow cylinder 22 Inner hollow cylinder Upper annular space 23 Discharge device lower annular space 24 Electric motor

Wall 25 gearbox

 Feed 26 Arrow

 Feeding device 27 helix

 Visible air flow 28 Air gap

first medium 29

 oversize

 discharge

Claims

Ring-shaped cascade classifier with downstream rod basket sizer PATENT CHECK 1 . Plant (1) for sifting feed (10) comprising - at least one cascade classifier (2) for sifting a feed stock (10) into a coarse feed fraction from coarse material (14) and a first middle fraction from first middle goods (13), at least one rod cage sifter (3) arranged downstream of the at least one cascade sifter (2) in the visible air flow for separating the first middle product (13) into a fine material fraction (20) and a second middle product fraction from second middle product (21), characterized in that the at least one cascade classifier (2) is of annular design, wherein visual cascades (5) are arranged helically in a hollow cylinder (6) limited by an inner cylinder and by an outer cylinder. 2. Installation according to claim 1, characterized in that the inner and outer diameter and thus the gap width of the hollow cylinder (6) with the inner and outer diameter and thus the gap width of an annular material task for the at least one rod basket sifter (3) corresponds. 3. Plant according to claim 1 or 2, characterized in that the hollow cylinder (6) by the helical staircase-like view cascades and a partition in two helically interlocking, superimposed annular spaces (7, 8) is divided, wherein the feed material (10) a corresponding arranged on the outer wall feed device (1 1) in an upper annular space (7) passes, and wherein classifying air (12) passes through a corresponding arranged on the outer wall feed device in a lower annular space (8), wherein for sifting the Sichtluft (12) flows through column (5a) between the scroll cascades arranged view cascades (5) and thereby more easily entrained in the classifying air suspendable medium (13). 4. Installation according to one of claims 1 to 3, characterized in that a Austragsvornchtung for coarse material (14) at the lower end (16) of the upper annular space (7) is arranged, through which not suspendable in the classifying air Grobgut (14) rolls. 5. Plant according to one of claims 1 to 4, characterized in that the at least one Stabkorbsichter (3) has an inner annular annular gap in the form of a wooden cylinder (22) as Austragsvornchtung for the second Mittelgutfraktion from second Mittelgut (21), wherein the second Mittelgutfraktion from second medium (21) by a Austragsvornchtung from the plant (1) flows and outside the plant to the feed material (10) or to a crushing device flows. 6. Installation according to one of claims 3 to 4, characterized in that the at least one Stabkorbsichter (3) has an inner, annular annular gap in the form of a hollow cylinder (22) as Austragsvornchtung for the second Mittelgutfraktion from second Mittelgut (21) wherein the second middle fraction of second medium (21) flows through a discharge device into the upper annular space (7) of the cascade classifier and flows within the plant (1) to the feed material (10). 7. Installation according to one of claims 1 to 6, characterized in that a drive (24) for the at least one rod basket sifter (3) in the inner, free of Umlaufgut cylinder of the annular cascade classifier (2) is arranged. 8. Installation according to one of claims 1 to 7, characterized in that a discharge device (23) for fines (20) above the at least one rod basket sifter (3) is arranged. 9. Installation according to one of claims 1 to 8, characterized in that the angle of the plane of the visual cascades (5) is adjustable. 10. Installation according to one of claims 1 to 9, characterized in that the number of revolutions of the rod basket sifter (3) is independent of the air pressure of the classifying air adjustable.