GB2121519A - Flap valve for a wet settling tank - Google Patents

Abstract

A flap valve for the working air of a settling tank used in the preparation of coal or other minerals has an electric drive. The drive may be e.g. a disc 1 with a linear motor arrangement 5, 6 at its periphery or any other electric drive e.g. a solenoid <IMAGE>

Description

SPECIFICATION Flap valve for a wet settling tank The invention relates to a flap valve, particularly a rotary flap valve with a central rocking shaft, forthe working air of a wet settling tank, which is preferably pulsated from below,forthe preparation of coal or other minerals.

Aflapofthe type in question is known from the FR-A1 2 480140,which which is moved by a double-acting cylinder. In this case, it is a disadvantage that the double-acting cylinder does not work without wear so that a constant supervision and maintenance is necessary. It is a further disadvantage that the cylinder must have control valves for its actuating air, which likewise do notworkwithoutwearand which likewise have to be supervised and serviced or replaced from timeto time. To this must be added the factthatthe double-acting cylinder has not inconsiderable space requirements.

The invention seeks to provide a driveforaflap valve, particularly for a rotary flap valve with a central rocking shaft, which works without significant wear and at the same time can be controlled in a satisfactory manner not hitherto achieved. Furthermore, the drive should have onlyvery small space requirements and be able to be constructed so that it forms an assembly unit together with the flap valve.

According to the invention, there is provided a flap valve, forthe working air of a settling tank, for the preparation of coal or other minerals, wherein the flap valve has an electric drive.

An electrical drive has the advantage that its individual parts are only in communication with one anotherthrough air gaps and so no wear takes place.

Thus reliable operation without servicing is possible for a long time, as with every electric motor. The main disadvantages ofthe known drive are completely avoided.

The electrical drive may be constructed in the form of a direct drive. Thus a trouble-free construction resultswith a minimum of moving parts which can, moreover, easily be connected to the flap valve to form a complete assembly unit. The space requirements are reduced and as a result of the possibility of the complete pre-assembly ofthe assembly unit in a specialized workshop combined with the field test device available there, an elimination of assembly errnrsalso results.

Thedrive may be constructed in the form of a disc.

Asa result of a disc-shaped form ofthe drive, the possibilityof producing largetorques in an electrical direct drive and of transmitting them reliably to the rocking shaft, results particularly advantageously. At the same time, a particularly short structural length in the direction of the axis of the rocking shaft can be achieved. The diameter of the electrical direct drive may correspond substantially to the size oftheflap valve housing.

The drive may be constructed in theform of a disc-shaped linear motor. The above advantages are combined in a disc-shaped linear motor.

The drive may be of multi-part construction and the individual partsofthe drive may comprise power control devices. Power control devices, preferably thyristor control devices, permit defined acceleration and braking curves which may possibly also be non-linearand which lead to a favourable pulse characteristic of the settling tank controlled via the flap valves, such as has not hitherto been achieved. Thus the mode of operation of the settling tank equipped with the flap valves according to the invention can surprisingly be still further improved.

The drive may comprise inductances in the form of parallel flat stacks of laminated metal sheets, in which windings are embedded and which are preferably completely cast integrally in plastics material. As a result ofthe use of parallel flat stacks of laminated metal sheetsforthe inductances, a particularly compact and space-saving drive device results which, in addition, is completely insensitive to environmental influences as a result ofthe embedding ofthe windings and laminated metal sheets in plastics material. Thus, in conjunction with the contactless operation, a drive resu its which is completelyfree of servicing and which cannot be harmed by moist air, dust, oil mist etc.Thus the use of the drive according to the invention is possible without problems even in an environment in which a corrosive attack on the individual partsoftheflap-valve drive unittakes place, as isfrequentlythe case in preparation plantsforcoal and other minerals.

The drive may be constructed in the form of a direct-current rotary magnet. In this alternative embodiment it is possible to use mass-produced parts which are cheaper than single-piece production.

Nevertheless, the structural size oftheflap-valve drive unit is not too large and the advantages of operation without wear in a unit which can be completely enclosed are retained with a control capacity which is still adequate.

The drive may comprise a driving dise which preferably runs at a constant speed of rotation and which has at least one controllable driving electromagnet. By this means, a construction results which likewise works without wear and which is particularly energy-saving. The driving disc needs only a small drive motor because it rotates at a constant speed, and the driving magnets, which are in communication with the rocking shaft, likewise need only a little electrical energy. They are disposed with spacing from the driving disc so that the whole arrangement works without contact and without wear.

The drive comprises a lifting magnet acting axially with a lifting rod acting on the shaft of the flap. This construction is particularly easy for the average conservative thinking expert in coal preparation to accept because it only goes one step in thought beyond the known double-acting pneumatic or hydraulic cylinder.

Furthermore, this construction makes the conversion of known rotary flap valves to an electrical version which works with little wear and can be controlled very satisfactorily, easily possible.

Finally, the drive may comprise brake and damping magnets which can be controlled individually and/or resilient stops. The movement behaviour of the valve according to the invention can be still further improved by brake and dampingmagnetsand likewise by resilient stops. This applies in particularto the embodiment in which no use is made ofthe directcurrent lineartechnique.

The invention will now be described in greater detail, byway of example, with reference to the drawings, in which: Figure 1 shows a linear-motorversion of a drive in accordance with the invention; Figure 2 shows a version with a driving disc and two driving magnets; and Figure 3 shows a version with a double-stroke magnet.

In figure 1, 1 designates the driving disc of the flap valve with a central rotaty shaft 13. The driving disc 1 is connected, via a carrier 2 of band-shaped construction, to the secondary part ofthe linear motor which is oftwo-part construction and consists of an iron armature part3 and an aluminium armature part 4.

The parts 3 and 4 of the linear motor are likewise of band-shaped construction. Without contact with the aluminium armature part4,which may be disposed radially outwards in the manner shown but may also be disposed laterally on the driving disc 1, the primary partcomprisesthe separate inductances 5 and 6 which may likewise also be disposed laterally. The inductances have the form of a parallel flat stack of laminated metal sheets in which the windings (not shown) are embedded.The inductances 5 and 6 ofthe primary part are preferabley completely cast in plastics material so that a unit results which is completely insensitive to humidity etc. The distance between the primary part and the secondary part may amountto 1 to 2.5 mm; thus it is so great that surface contamination etc. have no influence.

According to the particularcondtions underwhich the drive is used, the corrosion-resistant aluminium can be replaced by copper or brass which enable a better dissipation of heat.

Two thyristor controls 7 and 8, which comprise seperate setting devices 9 and 10 forthe working pulse magnitude ofthe inductances 5 and 6, serve to control the two inductances 5 and 6. The working pulses are controlled by a pulse control 11 which is preferably likewise constructed in the form of an electronic pulse control and can be adjusted in the milli-second range. The working pulses are amplified in controls 7 and 8so that the linear motor produces the torque necessaryforthe rotation of the driving disc 1, within the scope ofthe required acceleration and deceleration curves.

In Figure2,20 designatesthe drive motorwhich runs at a constant speed of rotation and which is connected to driving magnets 23 via a shaft 21 and a driving disc 22. The drive motor 20 can be selected to be very small, about 250 to 500watts, because the flywheel moment of the driving disc 22 with the magnet 23 is so greatthat on the response of the magnets 23 only a drop in speed which can scarcely be measured results.

Attheworking side of the driving magnets 23 is the driving disc 24 which is connected to the valve flap, not shown, via the shaft 25. For the better guiding of the driving disc24, this comprises an inner bearing 27 in a sleeve 26 and isthmus connected to the motor shaft 21 for rotation The magnets 23 are likewise controlled via power thyristor and the pulse control according to the arrangement in Figure 1 and cause the movement of the driving disc 24without contact. Thus a drive system for a flap valve is achieved which works without contact, which is easyto enclose and works with the expenditure of particularly little energy.

In Figure 3,30 designates a double lifting magnet, the operating coils ofwhich are likewise controlled by acontrol corresponding to the control in Figure 1.The lifting magnet 30 is mounted laterally in plates 31 which are disposed on a common base Plate 33. It comprises spring elementsordamping and brake magnets 32 at its under side and likewise at its top. The actuation of rocking shaft 37 is effected via a connecting rod 34 and a bearing 35 which preferably consists of resilient plastics material working without lubrication. The bearing 35 is disposed directly on the swivel arm 36 which is rigidlyconnected to the rocking shaft 37. The flap valve is indicated in diagrammaticformat the side and is not designated in detail.

The rotaryflapvalve drive according to the invention is intended, in particular, for use in settling tanks which are pulsated from below. Without departing from the scope ofthe invention, however, it may likewise be used in tanks which are pulsated at the side, which hitherto comprised rotary slide valves with considerably more unfavourable opening and closing behaviour, or in air settling tanks which hitherto worked with rotating throttle valves. In any case, the advantages of operation without wear and which can be satisfactorily controlled result, wherein any desired valve opening and closing characteristics can be set, aswell asthe compactform of construction with the possibility of complete enclosure.

Claims (13)

1. Aflap valve, forthe working air of a settling tank, forthe preparation of coal or other minerals, wherein the flap valve has an electric drive.

2. Avalve as claimed in Claim 1, wherein the electric drive is constructed as a direct drive.

3. Avalveasclaimed inClaim ? or2,whereinthe drive is constructed in the form of a disc.

4. Avalve as claimed in Claim 1,2 or3, wherein the drive is constructed as a disc-shaped linear motor.

5. Avalve as claimed in Claim 4, wherein the drive is of multi-part construction.

6. Avalve as claimed in Claim 4 or 5, wherein the individual parts ofthe drive include power control devices.

7. Avalve as claimed in Claim 4,5 or6, wherein the drive comprises inductances in the form of parallel flat stacks of laminated metal sheets in which the windings are embedded.

8. Avalve as claimed in Claim 7, wherein the lamination windings are completely enclosed in an integral plastics material.

9. Avalve as claimed in Claim 1,2 or3, wherein the drive is constructed in the form of adirect-current rotary magnet.

10. Avalve as claimed in Claim 1,2 or 3, wherein the drive comprises a driving disc which runs at a constant speed of rotation and has at least one controllable driving electromagnet.

11. Avalve as claimed inClaim 1, or3, wherein the drive comprises a lifting magnet acting axially, with a lifting rod acting on the shaft ofthe flap.

12. Avalveasclaimed inoneofthepreceding Claims, wherein the drive comprises brake and damping magnets which can be controlled individually, and/or resilient stops.

13. Aflap valve forthe working and of a settling tank substantially as described herein with reference to the drawings.