CN1005760B - Separator for particulate material - Google Patents

Abstract

A sorter for sorting particulate material suspended in a conveying gas into coarse and fine particles has a rotor (1) with two sets of blades (9,10). The adjustment plates (13, 14) in the fine particle output pipe adjust the relative flow rate of the air flow through the two-blade device, thereby controlling the particle size of fine particles and coarse particles, and the coarse particles are thrown outward by the centrifugal force of the blades and fall in the casing (3) .

Description

Separator for particulate material

The invention relates to a separator for separating particulate material suspended in a transport gas into fine and coarse particles, comprising a rotor with blades, a housing enclosing the rotor, a feed duct leading to one end of the rotor for transporting unsorted material and a discharge duct leading from the other end of the rotor for discharging the separated fine particles. Such a sorter will be described hereinafter.

In such a classifier, the material, i.e. the suspension in the gas, passes through rotating blades, in which the coarser particles are thrown towards the inner wall of the casing under the influence of centrifugal force. Because the velocity of the gas stream near the inner wall is insufficient to entrain coarser particles, the particles fall along the inner wall to the bottom of the classifier, while finer particles continue to follow the gas stream through the bladed rotor and are discharged through the output duct of the classifier, whereupon the finer particles are separated from the gas by means such as a precipitator.

The separated fines are composed almost entirely of smaller particles smaller than a certain size, called first particles, while the coarse particles are composed almost entirely of larger particles larger than a certain size, called second particles. In addition, there is a medium particle distribution between the first and second particle sizes in both the fine and coarse particles. The distribution of medium size particles is due to the fact that it is not possible for the classifier to have a precise particle size separation cut-off, so that all particles smaller than a certain size are made to pass through the rotor and all particles larger than this size are thrown towards the inner wall of the housing.

The size difference between the first and second particles indicates the sorting accuracy, and the sorting accuracy and cut-off size of the sorter, i.e. the required particle size from coarse to fine, are special requirements for the design of the blade rotor. With ｃA rotor such as that known from figure 1 of european patent EP- ｃA-0073567, it is only possible to vary the particle size distribution of the finished product (fines) by varying the characteristics of the separator as described above, by adjusting the speed of rotation of the rotor and the speed of the suspension through the classifier.

Another known method of varying the characteristics of the classifier, i.e. the particle size distribution of the classified fine-grained product, is to use two or more of the above-mentioned classifiers simultaneously, for example in parallel or in series.

The object of the invention is to improve the ability to vary the characteristics of the classifier, which according to the invention is achieved in that, firstly, the rotor comprises at least two sets of blades having different classification characteristics, and, secondly, control means are provided for adjusting the relative proportions of the conveying gas passing through the different rotor blades.

With this classifier, the particle size distribution of the sorted product can be changed to a degree not currently possible with other devices. By controlling the flow velocity of the suspension through the blades, the rotor blades have different sorting characteristics, and there is the further advantage that the control of the sorter and the quality of the product can be controlled during operation.

The simple and compact rotor configuration of the classifier makes the classifier particularly suitable for use as a built-in classifier installed on top of a vertical mixer and greatly increases the range of applicability of the machine.

Advantageously, the classifier is constructed in such a way that each set of vane means has a separate outlet channel connected to the output duct of the classifier and the flow control means is mounted in the outlet channel.

In another arrangement, the control means may comprise an extension of the outlet duct which is adjustable relative to the other end of the rotor.

Several examples of sorters constructed in accordance with the present invention are illustrated by the accompanying drawings as follows:

FIG. 1 is an axial cross-sectional view through a classifier with two sets of rotor blades in the preferred position;

FIG. 2 is a similar illustration but with the second set of rotor blades in another position;

FIG. 3 is a view similar to FIG. 1 but showing another airflow control device.

The sorter of fig. 1 has a rotor 1 which is driven in rotation about a vertical axis by a motor (not shown) via a shaft 2. The rotor is enclosed by a cylindrical casing 3, the lower part of which constitutes an inlet duct 4 for the unsorted material suspended in the conveying gas to the lower end of the rotor 1.

At the top of the housing 3 is an outlet pipe 5, through which fine particles of the material separated by the rotor are carried away.

The rotor has an integral bottom plate 6 and a top plate 7. the plate 7 has a central outlet opening 8 which leads to the tube 5.

Between the bottom plate 6 and the top plate 7 of the rotor there is a first set of substantially radially distributed blades 9, to which a second set of substantially radially distributed blades 10 is fixed on the top plate 7 of the rotor.

Above the second set of blades 10 is an outlet pipe 11 connecting an upper region 12 in the housing 3 with the pipe 5.

Both pipes 5 and 11 are equipped with control means, such as: in the form of adjustment plates 13 and 14, respectively.

Alternative mounting positions for the blade arrangement are indicated by dashed lines 10a, 10b, 10c and 10d in fig. 2.

The vane means 10c may further be mounted in an axially adjustable manner, i.e. an adjustment means is provided for the classifier on a ring 17 around the vanes 9.

The operation of the sorter is as follows. The material to be sorted in the sorter is first suspended in a conveying gas, which is then moved upwardly into the lower part 4 of the housing 3, from where the suspension gas flow enters the rotor, passes through a first set of vanes 9 as shown in figure 1, and then exits the rotor through a central hole 8 in the plate 7 into the tube 5 (as indicated by arrow 15), while the remainder of the suspension gas flow moves directly upwardly into a second set of vanes 10, passes through the space 12 and exits through the outlet duct 11 into the tube 5 (as indicated by solid arrow 16).

During the passage through the rotating blades 9 or 10, the heavier particles are thrown out in a known manner by the centrifugal force of the rotor 1 in the direction of the housing 3 (as indicated by the broken arrows) and fall along the inner wall of the housing towards the bottom for further processing, for example in a crusher placed below the classifier.

When the two sets of vanes 9 and 10 have different sorting characteristics, it is possible to control the air flow velocities through the two sets of vanes by means of the regulating plates 13 and 14 in the outlet ducts 5 and 11, respectively, so that, in operation of the sorter, the respective fine fractions emerging from the two sets of vanes can be combined appropriately, so that the finished product exiting the sorter via the outlet duct 5 has the desired particle size distribution.

The combined position of the two sets of vanes 9 and 10 shown in figure 1 constitutes a parallel sorting mode, i.e. two air streams 15 and 16 of suspension each pass through only one set of vanes.

Blades 10a and 10b in figure 2 operate in the same manner as blade 110 in figure 1 with respect to blade 9, i.e. in a parallel sorting mode, whereas blades 10c and 10d operate in a combination of parallel and series with respect to blade 9, i.e. a flow of aerosol can pass through both sets of blades.

Thus, for blade 10c, the first flow of suspension passes only through blade 9, while the second flow passes through blades 10c and 9 and the third flow passes only through blade 10 c.

In the case of the blades 10d, all the suspension passes through the blades 10d, the flow coming out of which generally also passes through the blades 9, while the remainder is directed to the outlet pipe 11.

Figure 3 shows an alternative arrangement of the control means which regulates the airflow through the second set of vanes 10 and thus the airflow velocity through both sets of vanes.

The control means are constituted by an extension 18 of the delivery pipe 5, which is axially adjustable with respect to the top plate 7 of the rotor 1.

Thus, the relative proportion of suspension passing through the two sets of different vanes is variable in all arrangements.

Claims (6)

1. A separator for separating particles suspended in a conveying gas into fine and coarse particles, comprising: a rotor with blades and a housing enclosing the rotor, and having an inlet pipe for leading unsorted material to one end of the rotor and an outlet pipe from the other end of the rotor for discharging sorted fine particles, wherein the rotor of the separator comprises at least two sets of blades having different sorting characteristics, and wherein a control device (13, 14, 18) is used to adjust the relative proportions of conveying gas passing through the different rotor blade devices. 2. A separator according to claim 1, characterized in that each set of blade means (9, 10) has a separate output channel (8, 11) connected to the separator output pipe (5), and the air flow control device (13, 14) is installed in the output channel. 3. A classifier according to claim 1, characterized in that the control means consists of an extension (18) of the outlet pipe (5) which is axially adjustable relative to the other end of the rotor. 4. A classifier according to any preceding claim, characterised in that the first set of blade means (9) is mounted between the end plates (6, 7) of the rotor (1) and the second set of blade means (10, 10a, 10b, 10c) is mounted on one of the end plates. 5. A classifier according to any one of claims 1 to 3, characterised in that the second set of blades (10c) is mounted so as to be axially adjustable relative to the first set of blades (9). 6. A classifier according to claim 5, characterised in that the second set of blades (10c) are mounted on a ring (17) which surrounds the outer ends of the first set of blades (9) and is slidable axially thereof.