SCREENING APPARATUS

Abstract

A basket (1) for a shale shaker includes a front, solids discharge end (34) and a rear, feed end (36) spaced apart by opposed first and second sides (2,4). The first and second sides mount a drive mechanism (7). The drive mechanism includes a first eccentrically weighted shaft (12), mounted to the first side (2) of the basket for rotation about an axis transverse to the front to rear direction of the basket; a first shaft drive, coupled to the first shaft (12) and to a corresponding second eccentrically weighted shaft (12a), which is mounted to the second side of the basket (4) for rotation about an axis transverse to the front to rear direction of the basket. A drive module (48, 50) comprising two eccentrically weighted shafts mounted on bearings in a single housing (52) is also described.

Claims

1. A basket for a shale shaker, the basket comprising a front, solids discharge end and a rear, feed end spaced apart by opposed first and second sides; wherein the first and second sides mount a drive mechanism comprising: a) a first eccentrically weighted shaft, mounted to the first side of the basket for rotation about an axis transverse to the front to rear direction of the basket; b) a first shaft drive, coupled to the first shaft and to; c) a corresponding second eccentrically weighted shaft, mounted to the second side of the basket for rotation about an axis transverse to the front to rear direction of the basket; wherein at least the first shaft drive includes at least one coupling accommodating misalignment between the first and second eccentrically weighted shafts.

2. The basket according to claim 1 wherein the drive mechanism further comprises: d) a third eccentrically weighted shaft, mounted to the first side of the basket for rotation about an axis transverse to the front to rear direction of the basket; e) a second shaft drive, coupled to the third shaft and to; f) a corresponding fourth eccentrically weighted shaft, mounted to the second side of the basket for rotation about an axis transverse to the front to rear direction of the basket.

3. The basket according to claim 1 wherein the eccentrically weighted shafts are each mounted for rotation about a horizontal axis transverse to the front to rear direction of the basket.

4. The basket according to claim 1 wherein the eccentrically weighted shafts are each mounted so as to have the eccentric weighting in the plane of the corresponding first or second basket side.

5. The basket according to claim 4 wherein the eccentrically weighted shafts are each mounted so as to have the centre of mass of the eccentrically weighted shaft in the plane of the corresponding first or second basket side.

6. The basket according to claim 1 wherein further comprising a motor configured to drive the first shaft and which is mounted to the first side of the basket.

7. The basket according to claim 2 wherein further comprising a motor configured to drive the first shaft and which is mounted to the first side of the basket and a second motor configured to drive the fourth shaft and which is mounted to the second side of the basket.

8. (canceled)

9. The basket according to claim 2 wherein both the first and second shaft drives each have at least one coupling accommodating misalignment between the respective first and second pair and third and fourth pair of shafts.

10. The basket according to claim 2 wherein: a) the first shaft drive comprises a first drive shaft coupling at a first end to the first shaft and at a second end to the second shaft; wherein the couplings are universal joints or constant velocity joints; and b) the second shaft drive comprises a second drive shaft coupling at a first end to the third shaft and at a second end to the fourth shaft; wherein the couplings are universal joints or constant velocity joints.

11. The basket according to claim 1 wherein the shafts of the shaft drive or drives are tubes.

12. The basket according to claim 1 wherein the eccentrically weighted shafts are each in a respective housing.

13. The basket according to claim 2 wherein the first and third eccentrically weighted shafts are mounted for rotation in a common housing or to a common base; and wherein the second and fourth eccentrically weighted shafts are mounted for rotation in a second common housing or to a second common base.

14. The basket according to claim 1 wherein the shafts of the shaft drive or drives are provided with housings.

15. The basket according to claim 1 wherein the eccentrically weighted shafts are mounted for rotation in bearings to either side of the respective shaft.

16. The basket according to claim 1 wherein eccentric weighting for an eccentrically weighted shaft is provided by a radially extending arm on the shaft.

17. The basket according to claim 16 wherein the radially extending arm carries a weight or weights, distal to the eccentrically weighted shaft.

18. The basket according to claim 16 wherein the weighting of the radially extending arm extends axially.

19. The basket according to any one of claim 16 wherein the eccentrically weighted shaft is mounted for rotation in bearings to either side of the radially extending arm.

20. The basket according to claim 1 wherein the first and second sides of the basket each comprise a platform for mounting a base or a housing for an eccentrically weighted shaft.

21.-25. (canceled)

26. The basket according to claim 20 wherein the platform is sloped from the horizontal.

27. The basket according to claim 26 wherein the platform is V shaped, with each arm of the V providing an upwards facing surface for supporting or locating a base or a housing.

28. The basket according to claim 1 wherein the first shaft drive comprises a relatively lighter weight material than the material of the first and second eccentrically weighted shafts.

29. The basket according to claim 13, wherein the common housing is modular and configured for location on either side of the basket.

30. A drive mechanism for the basket of a shale shaker comprising: a) a first shaft, eccentrically weighted and mountable in use to a first side of a shale shaker basket, for rotation about an axis transverse to the front to rear direction of the basket; b) a first shaft drive, coupled to the first shaft and to; c) a corresponding second eccentrically weighted shaft, mountable in use to a second side of the shale shaker basket, opposite the first side, for rotation about an axis transverse to the front to rear direction of the basket, wherein at least the first shaft drive includes at least one coupling accommodating misalignment between the first and second shafts.

31. The drive mechanism of claim 30 further comprising: d) a third eccentrically weighted shaft, mountable in use to the first side of the shale shaker basket for rotation about an axis transverse to the front to rear direction of the basket; e) a second shaft drive, coupled to the third shaft and to; a corresponding fourth eccentrically weighted shaft, mountable in use to the second side of the basket for rotation about an axis transverse to the front to rear direction of the basket.

32. A drive module for a basket of a shale shaker, the drive module comprising two eccentrically weighted shafts mounted on bearings in a single housing and configured for mounting to the first side or the second side of a shale shaker basket so as to provide either the first and third, or the second and fourth, eccentrically weighted shafts of a drive mechanism in accordance with claim 31.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] FIGS. 1a, 1b, 1c, 1d and 1e show various aspects of prior art shale shaker baskets with prior art drive mechanisms;

[0042] FIGS. 2a and 2b show in schematic views a shale shaker basket and a drive mechanism of the invention;

[0043] FIGS. 3a and 3b show in schematic views the sides of a shale shaker basket fitted with a drive mechanism of the invention;

[0044] FIGS. 4a and 4b show in schematic perspective views a shale shaker basket fitted with a drive mechanism of the invention;

[0045] FIG. 5a shows in schematic perspective a shale shaker basket fitted with a drive mechanism of the invention;

[0046] FIG. 5b is a side elevation of the basket of FIG. 5a;

[0047] FIG. 5c is a schematic cross section of a module housing showing an eccentrically weighted shaft of a drive module within; and

[0048] FIG. 5d shows the interior of the module of FIG. 5c in side elevation, showing the two eccentrically weighted shafts of a drive module within.

DESCRIPTION OF SOME EMBODIMENTS BY WAY OF EXAMPLE

[0049] FIG. 1a shows in schematic end elevation parts of a prior art basket 1 of a shale shaker. The first and second sides 2,4 of the basket 1 are shown viewed from the front solids discharge end (not shown in this figure). The sides 2,4 are supported on springs 5 in the usual way to allow vibratory motion.

[0050] Mounted to the sides of the basket by bolts 6 is a drive mechanism 7 for imparting vibratory motion to the basket 1. The drive mechanism 7 includes supporting end plates 8 with a pair of casing tubes 10 forming a bridge from one basket side 2 to the other 4. Within each casing tube 10 is a shaft 12,13 that has an eccentric weight 14 provided along its length. See cross section of shaft and weight in FIG. 1c. Only one casing tube 10 and its contents is visible in FIG. 1a as, in this example, the shafts are at the same height. FIG. 1b shows mechanism 7 as viewed from direction X.

[0051] Shafts 12 are mounted in bearings 16. An electric motor 18 drives the shaft 12 visible in FIG. 1a by belt 20. A corresponding motor 22 at the other side of the drive 7 powers the second shaft 13. The drive mechanism 7 is substantial in weight with casings 10 and end plates 8 constructed of metal (steel) to support the masses and forces involved.

[0052] In use rotation of shafts 12,13 imparts vibratory motion, for example elliptical vibratory motion to the basket 1 by virtue of the motion of the eccentric weights 14. The direction and type of vibratory motion imparted to the basket 1 depends on factors including: the spacing between shafts 12,13; the mass and relative angular displacement of weights 14; the rotational speeds of the shafts; and the rotational direction of the shafts. As suggested by double headed arrow Y in FIG. 1a the rotation of eccentric weight 14 imparts significant bending force on shaft 12 and hence stress on bearings 16.

[0053] FIGS. 1d and 1 e illustrate schematically two other prior art arrangements.

[0054] In FIG. 1d each side 2, 4 of the basket 1 has a drive mechanism 7 attached to its outer side. The mechanisms 7 have moving members such as eccentrically weighted, shafts driven by electric motor, to impart vibratory motion. As suggested by double headed arrows B, the location of the relatively massive drive mechanisms 7 can impart significant bending motion to the basket sides 2,4.

[0055] In FIG. 1e a bridge 23 between basket sides 2, 4 carries a drive mechanism 7. The mechanism 7 has a moving member or members such as eccentrically weighted, shafts driven by electric motor, to impart vibratory motion. The location of the mechanism 7 mid way between the basket sides 2,4 can impart significant bending motions B to the basket sides.

[0056] FIG. 2a shows a basket 1 in a similar schematic view to that of FIG. 1a but provided with a drive mechanism 7 in accordance with an embodiment of the invention. Drive mechanism 7 includes housings 24, 24a connected by tubing 26 and coupling housings 28, 28a. As shown in partial detail schematic FIG. 2b the housing 24 mounted to basket side 2 contains a short shaft 12 mounted on bearings 16 to either side and carrying an eccentric weight 14. Eccentrically weighted shaft 12 is coupled by a universal joint (not shown) inside coupling housing 28 to a tubular drive shaft 30 inside tubing 26 that acts as its housing. The drive shaft 30 connects to a corresponding eccentrically weighted shaft 12a in housing 24a mounted to basket side 4 via a further universal joint in the coupling housing 28a. The pair of eccentrically weighted shafts 12 and 12a are coupled by the shaft drive including shaft 30 and the universal joints. The arrangement is driven by electric motor 18 via belt drive 20.

[0057] As suggested by double headed arrows D the vibratory motion provided by each eccentrically weighted shaft acts directly on the basket sides 2,4 as the mass of shafts 12, 12a and associated weights 14 is positioned above respective basket sides. The eccentrically weighted shafts are each mounted so as to have the eccentric weighting in the plane of the corresponding first or second basket side as indicated by lines Z. In this example the centre of mass of each eccentrically weighted shaft is in the plane of the corresponding basket side.

[0058] The short shafts 12, 12a tend to produce less wear on bearings 16 as they are less prone to significant bending. Drive shaft 30 and associated universal joints provide a shaft drive arrangement that can be lightweight as it is not heavily loaded. Similarly housings 26 and 28 are not bearing a significant load and can be light, providing only separation of moving parts from an operator, for safety.

[0059] FIGS. 3a and 3b show in schematic elevation first and second sides 2, 4 of a shale shaker basket including a drive system 7 incorporating two of the drive arrangements of the type illustrated in FIGS. 2a and 2b.

[0060] In this example the housings 24 of drive system 7 sit on (are bolted to) a lowered edge or platform 32 of each basket side 2,4 which in this example is towards the front, solids discharge end 34 of the basket, and somewhat further away from the rear, feed end 36. A first drive arrangement 37 has housings 24, 24a including eccentrically weighted shafts and coupled via a drive shaft in the same way as illustrated in FIGS. 2a and 2b. Drive is provided by electric motor 18 and belt drive 20 located on basket side 4.

[0061] The second drive arrangement 37a has housings 24b and 24c including eccentrically weighted shafts and coupled via a drive shaft in the same way as illustrated in FIGS. 2a and 2b. Drive is provided by electric motor 22 and belt drive 20 located on basket side 2. In this example the second drive arrangement 37a is elevated by being mounted to the basket sides via platforms 38. Changing the relative positions of the drive arrangements along lowered edges 32 and/or their heights relative to each other can be used to adjust the vibratory motion (type and direction) imparted to the basket 1.

[0062] FIGS. 4a and 4b show in more detailed perspective views from either side; a basket and drive system of the type depicted in FIGS. 3a and 3b, to illustrate further the arrangements in a shale shaker basket 1.

[0063] In FIG. 4a a first drive arrangement 37 of drive system 7 has housings 24, 24a including eccentrically weighted shafts and coupled via a drive shaft in tubular housing 26. Drive is provided by electric motor 18 and belt drive 20 (located in a housing 40) on basket side 4.

[0064] The second drive arrangement 37a has housings 24b and 24c including eccentrically weighted shafts and coupled via a drive shaft in a second tubular housing 26. Drive is provided by electric motor 22 and belt drive 20 (located in a second housing 40a) on basket side 2.

[0065] The eccentrically weighted shafts of the drive arrangements 37, 37a are transverse to the front to rear direction of the basket suggested by arrow Y and also substantially horizontal.

[0066] In this example the second drive arrangement 37a is elevated by being mounted to the basket sides via platforms 38. Changing the relative positions of the drive arrangements along lowered edges 32 and/or their heights relative to each other can be used to adjust the vibratory motion (type and direction) imparted to the basket 1. In this example the drive arrangements 37, 37a are bolted to lowered edges 32 of basket 1.

[0067] Also shown in these views are the front, solids discharge end 34 of the basket, the rear, feed end 36; and a stack of three screen assemblies 42, one above the other.

[0068] The screen assemblies have screening surfaces 44 (only the topmost visible) for screening a drilling mud and drilling cuttings mixture applied at the rear, feed end 36.

[0069] The basket depicted has four mounts 46 for spring supports (not shown) on which it will sit to allow vibratory motion.

[0070] FIG. 5a shows in schematic perspective an alternative basket arrangement mounting modular drive arrangements. Basket 1 has sloping platforms 32 on each basket side 2, 4. In this example, platforms 32 have a generally V shape providing two upwards facing surfaces that are for supporting or locating bases or housings of modules 48, 50 mounted to respective basket sides 2,4.

[0071] The modules 48, 50 each have a main housing 52 that holds two eccentrically weighted shafts each mounted within the housing on bearings to either side of the eccentric weight as illustrated in FIGS. 5c,5d discussed below. On each module one of the eccentrically weighted shafts is driven by belts (inside belt housing 54) from electric motor 22. The other eccentrically weighted shaft in each module is driven by the drive shaft of a shaft drive inside one of the two tubings 26. The modules 48, 50 are identical and so can fit to either side 2, 4 of the basket 1.

[0072] The desired difference in height H and horizontal spacing S between the pairs of eccentrically weighted shafts within the housings of the modules 48,50 is determined by the slope of platform 32 and the spacing between the location of the shafts within main housing 52, as indicated in side elevation FIG. 5b.

[0073] Also visible in FIGS. 5a and 5b are a series of reinforcing ribs 56, 56a of sheet steel. The ribs are spaced apart and substantially parallel. The ribs 56a support platform 32, the ribs 56 support flanges 58 at the top edges of sides 2,4 towards feed end 36 of the basket.

[0074] The ribs slope downwards from the top edge of the basket side towards the bottom edge, in a direction towards the back (feed receiving end 36) of the basket. The downwards sloping angle, towards the back end 36 of the basket, approximates the typical angle of the vibratory motion that will be applied to the basket. Thus the ribs 56, 56a provide reinforcement to the basket sides.

[0075] FIG. 5c shows in schematic cross section a main housing 52 of a module to illustrate the mounting of one eccentrically weighted shaft 12. The shaft 12 is mounted in bearings 16 to either side. The bearings 16 are each themselves mounted in a housing 60 of the main housing 52 and protected by seals 61. Shaft 12 includes a radially extending arm 62 in between bearings 16 that mounts weights 64 to provide eccentric weighting. The weights 64 are distal to shaft 12 and extend axially from arm 62 (in the shaft direction). Each weight 64 extends to radially opposite the respective bearing 16.

[0076] The bearings 16 are close to and to either side of radially extending arm 62, providing a compact and durable arrangement.

[0077] The weights 64 can be unbolted from arm 62 and so replaced by different weights, to suit operational requirements. Drive to shaft 12 is by belts to pulley 66 mounted at one end. An electric motor (not shown in this figure) can provide the drive to the pulley. The opposite end 68 of shaft 12 will connect to a shaft drive, for example by a universal joint, in use.

[0078] FIG. 5d shows the main housing 52 of FIG. 5c in side elevation cross section showing the two eccentrically weighted shafts 12 within the housing 52. In this view the radially extending arms 62 on shafts 12 can be seen to be part circle in form, as are the weights 64. Bolts 70 hold the weights 64 on to arms 62. The two arms 62 extend radially from their corresponding shaft 12 at different angles, to provide the desired vibratory action in use.