GB2185904A - A cleaning device for a filter press - Google Patents

Abstract

A cleaning device for a filter press comprises a spray tube (27), mounted for pivotting about an axis (28) between a horizontal position above the filter press plates and a vertical position between separated plates. The spray tube is moved along the press from one pair of separated plates to the next on a carriage (4), while in its horizontal position, then pivotted to the vertical position and moved across the press between two plates on a second carriage (20), which runs on rails across the carriage (4). The carriages and spray tube may be lifted from rails (9) along one filter press and mounted on corresponding rails on another press, as required, so that one cleaning device serves several presses. When tube (27) is horizontal it lies within the width and height of carriage (4). <IMAGE>

Description

SPECIFICATION Cleaning Devices for Filter Presses The present invention relates to cleaning devices for filter presses, the presses comprising a series of cloth covered filter plates which in use are held together when wet slurry material is pumped between the plates thereby tending to urge water from the material. In repeated use the filter cloths tend to remain at least partially covered with material after the treatment is completed and the pressing action is removed from the plates.

It is well known in various industrial processes, for example in Coal Preparation, to filter a slurry in a recessed plate filter press. Such a press comprises a stack of filter plates which are held in a vertical plane and which may be compressed together by a hydraulic or mechanically operated ram or rams between a fixed end plate, known as a 'king plate', and a moving end plate. The support structure for the press consists of two end supports which are connected by side bars on which the moving plates slide. The king plate forms an integral part of one of the end supports. The major surfaces of each plate are recessed below the edge flange and are covered with filter cloths so that adjacent plates form a chamber between them when the edge flanges are pressed together. The plates and filter cloths have a hole through which slurry can be pumped into the press chambers.Drainage channels behind the cloths allow filtrate which passes through the cloths to escape from the press through ports in the edges of the plates.

When filtration is to take place the plates are closed up against the king plate by a ram or rams so that they form a solid pack with the fixed king plate.

Slurry is pumped under pressure through the feed holes in the plates so that it fills each of the press chambers. The slurry pressure forces filtrate through the cloths and solids are trapped on the cloth surface where they build-up and form a filter cake. When the filtration is considered to be complete the slurry pumping ceases. To remove the filter cake from the press, the moving end plate is withdrawn from the pack of plates so that the filter cake between the moving end plate and the adjacent plate can fall out of the end chamber. Each subsequent plate is then moved separately towards the moving end plate so that each filter cake can drop out in its turn. When all the filter cakes have been discharged, the whole pack of plates is located against the moving end plate and there is a gap between the plate pack and the king plate.The ram or rams are then operated to close the press by moving the moving end plate and the other plates, as a pack, up against the fixed king plate sothatthe filtration cycle may be repeated.

Because of the nature of the coal and clays contained in the slurry it is necessary to periodically wash the filter cloths so that efficient filtration is maintained. Washing of the filter cloths is normally carried out in situ and is either a manual operation with a hand held water spray lance or is performed automatically by a device supplied as an integral part of the filter press construction. The filter cloth washing operation is activated at the end of a filtration cycle when all the plates have been withdrawn towards the moving end plate and a gap exists between the plate pack and the fixed king plate. Each plate is then moved separately towards the king plate with one pair of filter cloths being cleaned before the next plate is moved forward.This operation continues until all the plates contained in the plate pack have been moved towards the king plate and a gap exists between the last plate and the moving end plate. A known automatic device to perform the cloth washing operation comprises of a spray tube provided with a plurality of spray nozzles for directing cleaning sprays towards the filter cloths. Movement of the spray arm across the face of each pair of filter cloths is activated once the spray tube has been located between a pair of plates. Movement of the spray tube as each plate is transferred towards the fixed king plate position is either incorporated with the plate movement mechanism or separately sensed.

It is known to provide cleaning devices for the plates comprising spray tubes provided with a plurality of spray nozzles for directing cleaning sprays towards the plates. On completion of the treatment process neighbouring plates are separated and the spray tube is traversed between neighbouring separated plates. With one such known cleaning device the spray tube is pivotally mounted to pivot vertically downwards towards the gap between the separated plates. Unfortunately, with the prior known cleaning devices the spray tube when in its pivotally lowered position does not reach down to the bottom regions of the separated plates and further lowering mechanism is required to lower the spray tube into a position in which all the adjacent surface area of the two separated plates can be sprayed.Two examples of such prior known cleaning devices are disclosed in British patent specification No. GB 2 154 460A.

An object of the present invention is to provide a cleaning device for a filter press which does not require the further spray tube lowering mechanism and which thereby tends to be less complicated and more compact in its construction.

According to the present invention a cleaning device for a filter press including a framework and a plurality of substantially vertical filter plates movably mounted with respect to the framework, comprises a spray tube, a carrier arrangement for traversing the spray tube along and across the filter press, and pivotal mounting means on the carrier arrangement for pivoting the spray tube for movement between two operational mode positions, in the first mode of which the spray tube is substantially horizontal and located above the filter plates and substantially within the vertical dimensions of the carrier arrangement, and in the second mode of which the spray tube is substantially vertical and located between neighbouring separated filter plates.

Preferably, the spray tube is located substantially within the horizontal dimensions of the carrier arrangement.

Preferably, the pivot axis for the spray tube lies substantially inline with or below a substantially horizontal plane including the uppermost edges of the filter plates.

Preferably, the carrier arrangement comprises two carriages, the first carriage in use being traversable to and fro along a track extending along the filter press, and the second carriage being traversable to and fro along a further track provided on the first carriage, the further track extending in a direction across the filter press.

Advantageously, the second carriage is traversable along the further track when the spray tube is in the second operational mode extending downwardly between separated filter plates.

Advantageously, the first carriage is removable from the track extending along the filter press.

Preferably, the spray tube is cranked comprising a linear spray tube element and a pivot arm extending transversely to the spray tube element, and pivot arm being pivotally connected to the pivotal mounting means.

According to another aspect, the present invention provides a filter press including a framework, a plurality of substantially vertical filter plates movably mounted with respect to the framework, and a cleaning device for the filter plates, the cleaning device comprising a spray tube, a carrier arrangement for traversing the spray tube along and across the filter press, and pivotal mounting means on the carrier arrangement for pivoting the spray tube for movement between two operational mode positions, in the first mode of which the spray tube is substantially horizontal and located above the filter plates and substantially within the vertical dimensions of the carrier arrangement, and in the second mode of which the spray tube is substantially vertical and located between neighbouring separated filter plates.

By way of example, one embodiment of the present invention now will be described with reference to the accompanying drawings, in which:~ Figure 1 is a perspective view of a cleaning device for a filter press, the cleaning device being shown in an operational position mounted on the filter press, only a sketchy detail of the filter press is shown; Figure 2 is a front elevation of the cleaning device of Figure 1; Figure 3 is a side elevation of the cleaning device of Figure 2; Figure 4 is a plan of the cleaning device of Figure 2; and Figure 5 is a plan of a detail of Figure 3.

The drawings show a cleaning device for a filter press including an elongate horizontal supporting framework (not shown) and a series of stack of substantially vertical cloth covered filter plates 1 arranged face to face (for the sake of clarity only sketchy details of the filter press is shown and parts of some of the filter plates are indicated in broken lines). The filter plates 1 are movably mounted with respect to the framework along supporting guide rails 2 (see Figures 1 and 2) extending longitudinally along the framework. Each filter plate is provided with supporting side brackets 3 (see Figure 1) slidably engaging the guide rails 2.

In use, prior to wet slurry being introduced into the filter press the plates are held together by rams (not shown) so that when the wet slurry is pumped into the chambers provided between neighbouring plates excess water is urged to flow through the filter cloths. Upon the water content of the slurry material being reduced to a desired amount the pressurising reaction is removed and the filter plates separated to allow the treated material to fall to the base of the framework from where it is conveyed. The treatment process then is repeated for the next batch of wet slurry treatment.

After a preselected number of treatments the filter plates are cleaned to remove material adhered to the cloths covering the plates.

The cleaning device shown in the accompanying drawings comprises a first carriage 4 including a framework having two side plates 5 and three cross members consisting of an upper tubular cross member 6 and two open sided lower channel cross members 7. The first carriage also has two pairs of wheels 8 engaged on two rails 9 and a pair of toothed drive sprockets 10 fixedly mounted on one pair of wheels 8 for rotation with the wheels, the drive sprockets 10 drivably engage a toothed rack 11 fixed to the rails 9 by connectors 12. The rails 9 and racks 11 are fixedly mounted across the supporting framework of the filter press.

The driven sprockets 10 are driven by a motor 13 drivably connected via gearing 14 including a belt drive to one axle 15 of the carriage. A trailing water hose 16 is connected to a swivel coupling 17 provided on the first carriage, the swivel coupling also being hydraulically connected to a flexible water hose 18 extending to a second swivel coupling 19 provided in a second carriage 20 arranged to travel across the first carriage. The trailing hose 16 is supported in pulleys 21 (see Figure 2) secured to one of the rails 9.

The second carriage 20 comprises a supporting framework including two interconnected side plates 22 supporting two pairs of wheels 23 (only one of which is shown in Figure 4) which are captivated inside to open sided channel cross members 7. The second carriage 20 also comprises a compressed air driven piston arrangement 24 (see Figure 4) mounted within the aforementioned tubular cross member 6 provided on the first carriage, the piston arrangement including a connector link 25 (see Figure 2) extending through a longitudinal slot (not shown) in the base of the tubular cross member 6 to the second carriage framework. The slot is sealed closed on both sides of the piston ensuring compressed air fed into the tubular member acts on the piston to move the carriage across the filter press. Thus, activation of the piston arrangement drive the second carriage to and fro along the open sided channel across members 7 and thereby to and fro across the width of the filter plates. Movement of the flexible hose 18 due to cross travel of the second carriage is indicated by 18' in Figure 4.

The second carriage supports pivotal mounting means 26 for a spray tube 27 such that, in use, the spray tube is pivotally moved between two operational mode positions, in the first of which the spray tube is substantially horizontal and located above the filter plates and substantially within the vertical dimensions of the first carriage, and in the second operational mode of which the spray tube is substantially vertical and located between neighbouring separated filter plates. The spray tube is indicated in its first mentioned operational mode by reference number 27' in Figures 2 and 3, and is indicated in its second mentioned operational mode by reference number 27 in all the Figures.

As indicated in Figure 3 the spray tube is located substantially within the horizontal dimensions of the first carriage. As indicated in Figure 2 the pivot axis 28 for the spray tube lies substantially inline with or below a substantially horizontal plane including the uppermost edges of the filter plates 1.

Also as indicated in Figure 2 the spray tube 27 is cranked and comprises a linear spray tube element 29 and a pivot arm member 30 extending transversely to the spray tube element, the pivot arm member 30 being pivotally connected to the pivotal mounting means 26. The pivotal mounting means 26 comprises two downwardly extending arms 31 interconnected by a pivot pin 42 upon which two limbs of the pivot arm members 30 are mounted. The arms 31 are formed integral with the side plates 22.

The spray tube is pivoted between its two operational modes by a compressed air drive 32 including rams driving toothed racks to rotate a driven sprocket (details of the drive are not shown).

The driven sprocket is drivably mounted on a rotary shaft 33 drivably supporting two arms 34 which are drivably connected to the two limbs of the pivot arm member 30 by connecting link rods 43. Thus, in use, when a suitable compressed air supply is fed to the drive 32 the shaft 33 is rotated to raise or lower the spray tube between its two operational modes.

As indicated in Figure 1 the linear spray tube element is provided with a plurality of spray nozzles 35 arranged to spray water towards the separated filter plates 1 on both sides of the cleaning device.

(For the sake of clarity most of the spray nozzles are not shown in some drawings).

As indicated in Figures 1 and 5 the spray nozzles are inclined to the filter plates in order to assist scouring of the cloth covering the filter plate surfaces to remove any slurry material adhering to the cloth surface after the preselected number of treatments.

It will be appreciated that the construction of cleaning device enables a low head filter press to be achieved and thereby assists in housing the press in plants with restricted head room. It also enables the cleaning device to be fitted to many existing filter press plants.

Also the fact that the cleaning device can be dismounted from the rails 9 and rack 11 enables one cleaning device to be used with several filter presses, each press being provided with only a pair of rails 9 and racks 11.

In operation, when a preselected number of treatments have been completed the filter plates 1 are separated and the first carriage is driven until the spray tube is over the gap between the first two filter plates. The drive 30 then is activated to pivot the spray tube down from its first operational mode in which it was located horizontally over the filter plates into its second operational mode in which it is located vertically adjacent to one side of the associated filter plates. Control means then switch on the water to the outlet spray nozzles 35. Water is fed to the outlet spray nozzles from the aforementioned swivel coupling 19 via a series of rigid pipes 36 and a further swivel coupling 37. A rigid pipe 38 feeds water along one limb of the pivot arm member 30.

Upon water being discharged from the outlet spray nozzles the piston drive 24 is activated to urge the second carriage along the channel member 7, thereby the spray tube is moved relatively slowly across the filter plates 1 to clean the co-operating faces of the separated plates.

When the carriage reaches the end of its cross travel the control means reverse the travel of the second carriage until the spray tube arrives back at its original vertical position. The water then is turned off and the drive reactivated to pivot the spray tube upwards to its original operational mode located horizontally within the vertical dimension of the first carriage. The drive 13 then is activated to move the first carriage until the spray tube is directly overthegap between the next two previously separated filter plates and the whole cleaning process repeated. Upon the completion of each cleaning process the first carriage is moved to the next pair of previously separated filter plates and so on until all the filter plates have been cleaned. The filter press then is operated for a further preselected treatment before the cleaning operation is repeated.

As explained previously, when the cloths covering all the plates have been cleaned, if required the cleaning device can be removed from the rails 9 and rack 11 and mounted on another similar filter press.

Thus, only one cleaning device is required for several filter presses.

In a modified embodiment, resilient means are provided to urge the spray tube upwards to its original operational mode.

Claims (10)

1. A cleaning device for a filter press including a framework and a plurality of substantially vertical filter plates movably mounted with respect to the framework, comprising a spray tube, a carrier arrangement for traversing the spray tube along and across the filter press, and pivotal mounting means on the carrier arrangement for pivoting the spray tube for movement between two operational mode positions, in the first mode of which the spray tube is substantially horizontal and located above the filter plates and substantially within the vertical dimensions of the carrier arrangement, and in the second mode of which the spray tube is substantially vertical and located between neighbouring separated filter plates.

2. A device as claimed in claim 1, in which the spray tube is located substantially within the horizontal dimensions of the carrier arrangement.

3. A device as claimed in claim 1 or 2, in which the pivot axis for the spray tube lies substantially inline with or below a substantially horizontal plane including the uppermost edges of the filter plates.

4. A device as claimed in claim 1, 2 or 3, in which the carrier arrangement comprises two carriages, the first carriage in use being traversable to and fro along a track extending along the filter press, and the second carriage being traversable to and for along a further track provided on the first carriage, thefurthertrackextending in a direction across the filter press.

5. A device as claimed in claim 4, in which the second carriage is traversable along the further track when the spray tube is in the second operational mode extending downwardly between separated filter plates.

6. A device as claimed in claim 4 or 5, in which the first carriage is removable from the track extending along the filter press.

7. A device as claimed in any one of the preceding claims, in which the spray tube is cranked comprising a linear spraytube element and a pivot arm extending transversely to the spray tube element, the pivot arm being pivotally connected to the pivotal mounting means.

8. Afilter press including a framework, a plurality of substantially vertical filter plates movably mounted with respect to the framework, and a cleaning device for the filter plates, the cleaning device comprising a spray tube, a carrier arrangement for traversing the spray tube along and across the filter press, and pivotal mounting means on the carrier arrangement for pivoting the spray tube for movement between two operational mode positions, in the first mode of which the spray tube is substantially horizontal and located above the filter plates and substantially within the vertical dimensions of the carrier arrangement, and in the second mode of which the spray tube is substantially vertical and located between neighbouring separated filter plates.

9. A cleaning device substantially as described herein and substantially as shown in the accompanying drawings.

10. A filter press including a cleaning device substantially as claimed in any one of the preceding claims 1 to 7 or claim 8.