IMPROVEMENTS IN OR IN RELATION TO SUGARCANE PROCESSING

Abstract

A slotted conveyor floor 16 in milling tandem, slots 34 extend across the direction of liquid flow shown by arrow 35 which is against the flow of fibre. The slots are cut through the material of floor 16 on the vertical as depicted by centre-line 35 taken relative to the inclination of floor 16. Thus the centre-line corresponds to gravity feed for the liquid. Rather than being directly across the floor 16, the slots are inclined in the direction of flow. The fibre is in the opposite flow relation to the liquid, in this example, the slots are across the line of the fibre and are about 6 mm wide and 180 mm long with about 60 mm spacing. Adjacent lines of slots are set interdigital in the direction of travel. This arrangement minimises fibre being trapped in the slots as the fibre is being carried by the rakes up the floor.

Claims

1. A slotted anti-clog conveyor floor for use in a sugar factory, the floor having a liquid flow direction and spaced apart anti-clog slots extending downstream and laterally across the floor.

2. A slotted anti-clog conveyor floor according to claim 1, the anti-clog slots being vertically oriented when the floor is in its operative position for liquid falling freely through the slots under the influence of gravity.

3. A slotted anti-clog conveyor floor according to claim 1, the anti-clog slots comprising vertically walled slots when the floor is in its operative position.

4. A slotted anti-clog conveyor floor according to claim 1 wherein the slots are cut through the floor along a centre-line inclined to the plane of the floor in the region of the floor adjacent the said slot.

5. A slotted anti-clog conveyor floor according to claim 1 wherein the slots are arranged in rows.

6. A slotted anti-clog conveyor floor according to claim 1 wherein the slots are evenly spaced.

7. A slotted anti-clog conveyor floor according to claim 1 wherein adjacent slots are set in interdigital relation across the floor.

8. A sugar mill having at least one inclined conveyor having a lower end and an upper end and a direction of travel for movement of fibre from the lower end to the upper end, the conveyor being set above an inclined conveyor floor running along and under the conveyor, the conveyor floor being perforated or having spaced slots extending across the conveyor floor, the perforations or slots having a hydraulic efficiency for liquid falling freely through the slots under the influence of gravity.

9. A sugar mill according to claim 8 wherein the hydraulic efficiency is defined by walls of the perforations or slots being set to promote juice flow while inhibiting fibre clogging.

10. A sugar mill according to claim 8 wherein the perforations or slots are set substantially vertical.

11. A sugar mill according to claim 8 wherein the slots are set to have a widest cross-section when viewed vertically in order to promote flow through the slots.

12. A sugar mill according to claim 8 wherein the slots extend across and down the floor in order to promote movement of fibre along the floor and inhibit fibre passing through the slots or clogging the slots.

13. A sugar mill according to claim 8 comprising a milling tandem of the type having at least two inter-mill conveyors with fibre moving up along the conveyors in a downstream direction, the improvement comprising: (i) a pressure feeder downstream and fed by a said conveyor, the pressure feeder leading into mill rolls; (ii) juice from the pressure feeder being delivered to the lower end of a conveyor upstream of the pressure feeder; (iii) juice from mill rolls following the said pressure feeder being combined with juice from further downstream and the combined juice also being fed to the lower end of the conveyor referred to in (ii); (iv) at least one of the said conveyors having a said conveyor floor adapted to promote juice flow through the floor while inhibiting fibre passage through the floor.

14. A sugar mill according to claim 8 wherein the conveyor has tines, paddles, or rakes spaced along the conveyor and these travel in closely spaced relation to the floor.

15. A sugar mill according to claim 8 wherein each inter-mill conveyor comprises a said floor.

16. A sugar mill according to claim 8 wherein, in (ii), juice from the said pressure feeder attached to a said preceding mill is delivered to a weir at a lower end of a said conveyor leading to the preceding mill.

17. A sugar mill according to claim 8 wherein, in (iii) juice from the mill rolls following the pressure feeder are combined with juice drained from a drainage tray under the conveyor which juice is pumped to a second weir on the conveyor preceding the mill directly in front and upstream.

18. A sugar mill according to claim 8 wherein, in (iv) each conveyor has a slotted conveyor floor adapted to promote juice flow through the floor while inhibiting fibre passage through the floor.

19. A sugar mill according to claim 8 wherein the floor comprises a slotted anti-clog conveyor floor having a liquid flow direction and spaced apart anti-clog slots extending downstream and laterally across the floor.

20. A sugar mill according to claim 8 comprising a milling tandem having five mills, each mill has six rolls, with fibre moving from a first mill through to an outlet downstream of the fifth mill, each mill having a pressure feeder followed by mill rolls, intermill conveyors comprising rake elevators, at least one of the elevators having a said conveyor floor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order that the present invention may be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein:—

[0031] FIGS. 1A and 1B together illustrate a schematic of a five mill tandem sugar mill incorporating the present invention;

[0032] FIG. 2 is an enlarged schematic of part of the milling tandem of FIGS. 1A and 1B;

[0033] FIG. 3 is a further enlargement side section of a conveyor floor used in the present invention approximating the section 3-3 of FIG. 4; and

[0034] FIG. 4 is a top view of a slotted conveyor floor pattern applied to the present invention and corresponding to the section of FIG. 3.

METHOD OF PERFORMANCE

[0035] Referring to FIGS. 1A and 1B, FIG. 1B is to an enlarged scale, and is a continuation of FIG. 1A. This means FIGS. 1A and 1B together represent a milling tandem. In this case, there are five mills, each mill has six rolls; thus there is a mill 1 through 5 illustrated. The number of mills in the tandem may vary as may the form of each mill. Relatively dry bagasse exits mill 5 at a downstream end at 10. Each mill has a pressure feeder at 11 followed by mill rolls at 12. The portion shown in the solid outline may be considered generally conventional. The conveyors may be conventional rake elevators. The dotted portions in FIGS. 1A and 1B correspond, in combination with conventional elements, to a preferred form of an improved mill according to the present invention.

[0036] Thus there is at an upstream end, a conventional feed chute 13 leading to a shredder 14 and then on to a first conveyor 15. Dotted is an improved conveyor floor at 16. This form of conveyor floor is repeated at each inter-mill conveyor 17, 18, 19 and 20 and will be described further in relation to FIGS. 3 and 4. Fibre is moved upward along this floor. Low pol juice is delivered at the lower end of each conveyor via pairs of weirs as will be described below.

[0037] In use the various liquid flows between the mills are depicted in the long dash lines in FIGS. 1A and 1B, The liquid generally travels in the opposite direction to the fibre.

[0038] Water is initially delivered at 21 on to fibre carried on conveyor 20 to macerate the fibre prior to the final mill. Subsequent low pol liquid flows through the conveyor floor 16 in the final conveyor and is collected via a drainage tray to flow along line 22. This liquid is combined with liquid from the fifth mill, mill rolls 10, and together this liquid is delivered to conveyor 19 of the second last mill along line 23 via an upstream weir at 24 where it is spread over fibre entering onto the floor 16 of conveyor 19.

[0039] Liquid collected from the pressure feeder 11 of mill 5 is fed to the bottom end of the conveyor 20 to a weir at 25 which flows onto fibre moving onto floor 16 of the conveyor 20. This process effectively repeats for mill 4 and conveyor 19 except there are two weirs. Liquid passing through the conveyor floor 16 of conveyor 19 flows along line 26 where that liquid is combined with liquid from the mill rolls of mill 4 and is delivered to a slightly upstream weir 27 of conveyor 18. It is applied over the fibre on the floor of conveyor 18. Liquid from the pressure feeder of mill 4 is applied to an upstream weir at 28 just below the weir 27. The weirs deliver liquid as near as practicable to the lower end of the conveyors to increase maceration time. In FIG. 2 they are slightly higher than shown in FIGS. 1A and 1B.

[0040] This process is repeated again for conveyors 16 and 17 and mills 1 and 2. Ultimately, the juice is delivered to process along line 29 via a rotary juice screen assembly 30 after being collected from the conveyor 15 through drainage tray 31 and the first mill roll set at 12 and along lines 32 and 33. The preceding description outlines the basic operation of the mill.

[0041] Important conveyor details are in FIGS. 3 and 4 which show the slotted conveyor floor used at 16.

[0042] Slots 34 in the pattern shown in FIG. 4 extend across the direction of liquid flow shown by arrow 35. The slots are cut through the material of floor 16 on the vertical as depicted in FIG. 3 by centre-line 35 taken relative to the inclination of floor 16. Thus the centre-line corresponds to gravity feed for the liquid. Rather than being directly across the floor 16, the slots are inclined in the direction of flow. The fibre is in the opposite flow relation to the liquid. In this example, the slots are across the line of the fibre and are about 6 mm wide and 180 mm long with about 60 mm spacing. Adjacent lines of slots are set interdigital in the direction of travel. This arrangement minimises fibre being trapped in the slots as the fibre is being carried by the rakes up the floor.

[0043] The vertical or gravity preferred cut improves hydraulic efficiency while the inclination in the flow direction and the narrow slots improves fibre filtration while also promoting the continued movement of fibre above and across the slots along the floor 16 rather than through the slots and also at the same time inhibiting fibre from blocking the slots.

[0044] Whilst the above has been given by way of illustrative example many variations and modifications will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as herein set out in the appended claims.