AU732606B2 - Improved sugarcane milling system - Google Patents

Description

rr I P/00/011 28/5/91 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Name of Applicant: Actual Inventor(s): Address for service is: Invention Title: BAPUSAHEB BHAURAO NIKAM BAPUSAHEB BHAURAO NIKAM WRAY ASSOCIATES 239 Adelaide Terrace Perth, WA 6000 Attorney code: WR "Improved Sugarcane Milling System" The following statement is a full description of this invention, including the best method of performing it known to me:-

I.

FIELD OF INVENTION The present invention relates to improvements in sugar cane milling system having at least one toothed feeder roller with Juice, drainage means, provided in singular, in addition, and adjacent to one or more conventional two or three roll mill tandem without using the conventional, closed stationery pressure chute, for increasing the fedability of prepared cane/bagasse in order to increase the cane crushing capacity and juice extraction efficiency of the mill with reduced power consumption and..

moisture of the bagasse.

BACKGROUND OF THE INVENTION In prior art, sugar cane crushing mill comprises a two roll mill module consisting of a top roll and a feed roll or a three roll mill module consisting of a top roll, a feed roll and a discharge roll. These rolls are made of cast iron or cast steel and are provided with peripheral grooves. A plurality of these main crushing mill modules are provided in tandem forming the cane crushing mill.

Main drawbacks of these cane crushing mills are 1. The bulk density of, the prepared cane/bagasse being fed to the mills, is very low which results into very low cane crushing rate of the mill.

2. There is a slippage between cane/bagasse and rolls, resulting into higher frictional losses and thus besides low cane crushing rate, power consumption is more.

3. Feed to discharge operating opening ratio is to be kept more, due to low bulk density and slippage of cane/bagasse, resulting into lower juice extraction and higherjuice reabsorption.

(Feed to discharge operating opening ratio means the ratio of the gap between top roll and feed roll to the gap between top roll and discharge roll in operating position of the mill i.e. in lifted/shifted position of the rolls against the hydraulic pressure) In the prior art, to increase the bulk density of the cane/bagasse, feeding equipment in the form of over/under feeder roller provided above or below the prepared cane mat, being fed through a conveyer and/or Donnelly chute, is incorporated with the crushing mill module. The over or under feeder roller is having peripheral grooves or axial or helical ribs.

These feeding equipments are also not able to provide any significant relief to the drawbacks, of the prior art cane crushing mill, described herein before, due to its inherent limitations of developing pressure.

Further in the prior art, a pair of grooved feeder rollers or a pair of toothed feeder 20 rollers is incorporated in front of the feed and top rolls of the main crushing mill S"module, nearly in a parallel plane and in-line i.e. having approximately same central axis. A closed stationary diverging pressure chute, having wider opening towards the main mill rolls, is required to be connected between the pair of feeder rollers "and the main crushing mill rolls.

The main draw-back of this arrangement is that the speed of the cane in comparison with the mill rolls surface speed is very low, which results into more frictional losses, more wear and tear and chocking in the cane feeding systemthere *by developing undue pressure leading to damage of various parts and hence there is frequent breakdown of the mill, resulting into low milling capacity besides high power consumption and maintenance cost. Additionally, skilled personnel are required for maintenance and operation of these mills.

Furthermore, in the prior art sugar cane crushing mills, the cush-cush soaked with juice in the strainer is fed into the mill module, under the strainer, for milling along with the bagasse.

The main drawback of this system is that the high purity of the juice in the cush-cush is recirculated through the mill module. This creates extra slippage, juice overloading and poor juice drainage and results in lower capacity and efficiency of milling.

Disclosure of the Invention It is therefore a primary object of this invention to provide a new and improved sugar cane milling system in which the bulk density of the cane/bagasse mat is increased and feed to discharge operating opening ratio is decreased by providing at least one toothed feeder roller with juice drainage means in addition to and adjacent to two/three roll mill modules. This will result in increased cane feedability, i.e. increased cane crushing capacity of a mill, along with higher juice extraction efficiency and lower power consumption.

oooo Accordingly this invention provides a sugar cane milling system comprising at least one toothed feeder roller with juice drainage means, the or each toothed feeder roller being provided in addition to and adjacent to a corresponding tandem mill module having at least two crushing rolls, the or each toothed feeder roller adapted to feed, when in use, a compact mat of prepared cane/bagasse directly to the nip of the crushing rolls of the module at S: substantially the same speed as the surface speed of the crushing rolls of the o: 25 module and without a sharp change in direction.

SThe toothed feeder roller may have its teeth projecting out of the roller shell in any manner, such as straight rows, zig-zag, helical, or any other staggered manner.

i -4- The teeth of the toothed feeder roller may be of any contour and shape.

The juice drainage means may comprise radial holes, slots or openings provided in the toothed feeder roller shell, in between the teeth forming perforated toothed feeder roller.

In another arrangement, the juice drainage means may comprise a scraper cum short deflector, provided against the said toothed feeder roller at a desired gap, between the said scraper and the tip, root and sides of the tooth of the toothed feeder roller. The scraper cum short deflector may be adjustably provided against the said toothed feeder roller permitting the said gap to be adjusted as per requirement.

The invention will be better understood by reference to the following description of several specific embodiments thereof as shown in the accompanying drawings in which: Figure 1 is a schematic end view of improved sugar cane milling system 15 according to an embodiment of the present invention, showing one oooo additional toothed feeder roller with scraper.

Figure 2 is a schematic end view of improved sugar cane milling system, according to another embodiment of the present invention, showing one additional toothed and perforated feeder roller with scraper.

20 Figure 3 is a perspective view of the toothed and perforated roller used in ***the system shown in Figure 2.

Figure 4 is part elevational view of the toothed and perforated feeder roller, seen in the direction of arrow marked in Figure 2.

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I.

Figure 5 is a sectional view along line y-y marked in Figure 4, showing the perforated toothed feeder roller with scraper of the system shown in Figure 2.

Figure 6 is a sectional view, along line z-z marked in Figure Figure 7 is a schematic end view of improved sugar cane milling system according to a further embodiment of present invention, showing two additional toothed feeder rollers with scrapers.

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Fig.8 is a schematic end view of improved sugar cane milling system, according to a further embodiment of this invention, showing three additional toothed and perforated feeder rollers with scrapers.

Fig.9 is a schematic end view of improved sugar cane milling system according to a further embodiment of the present invention showing one additional toothed feeder roller with scraper connected to a pilot feeder provided at the exit of Donnelly chute.

Fig. 10 is a schematic plan view of pressurized cush-cush juice extracting conveyor, used in the improved sugar cane milling system, according to present invention.

Fig. 11 is sectional and view along line X' marked in fig. Fig. 12 is sectional end view along line marked in fig. Fig. 13 is a schematic view indicating the juice extraction in the cone/taper portion of the conveyor shown in fig. Fig. 14. is a schematic plan view of the pressurised cush-cush juice extracting conveyor, according to another embodiment of the present invention.

In all the above figures, supporting/mounting and driving arrangements of the main mill rolls as well as additional feeder roller/s are not shown for the sake of simplicity and clarity of the inventive features of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Referring to Figs. 1 to 9 the improved sugar cane milling system of present invention comprises two or three roll mill modules provided in tandem. The two roll mill comprises a top roll 1 and a bottom (Discharge) roll 3. The three roll mill comprises a top roll 1, a feed roll 2 and a discharge roll 3. These rolls are made of cast iron or cast steel and are provided with peripheral grooves. Sometimes one or two of these rolls may be lotus rolls i.e. the rolls having radial holes provided at the periphery and connected to axial holes. The top roll is applied with hydraulic pressure for maintaining compression for juice extraction. For increasing the cane/bagasse fedability according to the present invention, at least one toothed feeder roller 4, as shown in fig. 1, is provided in addition to and adjacent to the main cane crushing rolls i.e. the top roll 1 and feed roll 2.

In fig. 7, two additional toothed feeder rollers 4 and 5 are shown and in fig. 8, three additional toothed feeder rollers 4,5 and 6 are shown.

The additional toothed feeder roller/s is adjustably provided with a scraper-cumshort defector 7 to scrap the cane/bagasse mat, stuck to the toothed feeder roller surface and to divert it towards the crushing mill module in the compact form. At the same time/simultaneously the scraper 7 also serves as a juice drainage means and removes the free juice in the prepared cane through the gap 8, between the scraper 7 and the toothed feeder roller the gap 8 is clearly seen in figs. 5 and 6) which comes out before going to mill and thus reducing juice load on the mill as well as reabsorption-absorption of the juice by the cane/bagasse.

According to another embodiment of this invention, as shown in figs. 3 to 6, the toothed feeder roller 4 can be replaced by a toothed and perforated feeder roller 9.

The roller 9 is provided with teeth 10, projecting out of its shell 11. Radial holes, slots or openings 12 are provided in the shell 11 in between the teeth 10. The teeth may have any contour or shape and are disposed of on the shell 11 in any manner i.e. in straight rows or Zig-Zag or helical or any other staggered manner.

The teeth 10 may be hard surfaced for more durability.

The teeth 10 may be hard surfaced for more durability.

I The radial holes, 12 serves as a juice drainage means and are able to remove free juice in the cane/bagasse while the toothed and perforated feeder roller 9 feeds the cane/bagasse, by compacting it, to the crushing mill module.

The scraper 7 may also be adjustably provided with the toothed and perforated feeder roller 9 to scrap the stuck cane/bagasse mat from the roller surface and to divert it towards the crushing mill module in the compact form and at the same time to remove the free juice, from the cane/bagasse being fed to the mill, through the gap 8 between the scraper 7 and the tip, root and sides of the tooth 10, thus the free juice in the cane/bagasse is removed through the radial holes 12 as well as through the gap 8 and is taken out without passing to the crushing mill, thus reducing juice load on the mill as well as juice reabsorption by the cane/bagasse being fed to the mill.

The free juice coming out through holes 12 and gap 8, being superficial juice is of low brix and low pol which is collected and recirculated over the same mill to absorb more sugar contents from the bagasse by efficiently using the same as maceration/ imbibition liquid.

The superficial juice may be passed over a strainer for separating out the cush-cush before recirculating over the mill.

The tip face of the scraper 7 is preferably hard faced and lined with stainless steel for better workability.

The feeder roller 4 or 9 is preferably driven by the top roll 1, with the help of known transmissioa means, like gear train or chain and sprocket drive (not shown) oo or if required it can be driven individually in a known manner.

In figs. 1,7 and 8 there are provided one, two and three additional toothed feeder rollers in addition to and adjacent to one or more three roll mill modules. Similarly further more toothed feeder rollers may also be provided for further compacting the prepared cane/bagasse, to further increase the cane crushing capacity.

These feeder rollers may have any combination out of toothed feeder roller and perforated toothed feeder roller and with or without scrapper.

Preferably the scrappers are adjustably provided keeping a desired gap between the scrapper and the roller shell and also work as a short deflector. The whole arrangement being such that the thickness 13 of the cane/bagasse mat 14 goes on successively reduced along its feed path 15 and the free superficial juice goes on extracting out at each successive stage so as to achieve much compacted cane mat without superficial juice to be fed into crushing mill module (see fig.8).This typical arrangement results into tremendous increase in milling capacity with increased juice extraction efficiency.

It is clear from figs. 7 and 8, that the typical arrangements of the additional toothed feeder rollers, do not require any closed stationary pressure chute, and very short S. 20 scrapper-cum-deflectors are used to divert the cane/bagasse directly into the nip of successive feeder rollers/mill rolls.

The feeder roller 4 in fig. 7 and each of the feeder rollers 4 and 5, in fig.8 acts at 25 two places/zones along the feed path of the cane/bagasse to compact the same 25 twice. As there is a limitation to provide a large number of additional toothed feeder rollers to the mill modules, alternatively, as shown in fig.9 a pilot feeder 16 is provided at the exit end 17 of the Donnelly chute 18 which in turn feeds the compacted cane/bagasse mat to the additional feeder roller modules of figs..1,2,7 or 8.

''It The pilot feeder 16 may be a toothed or ribbed roller (not shown) provided at one side of the exit end of the Donnelly chute or two toothed or ribbed rollers not shown provided at two opposite sides of the exit end of the Donnelly chute.

Preferably the pilot feeder 16 comprises a pair of belt conveyers 19 provided at the exit end 17 of the Donnelly chute 16, and converging towards toothed feeder roller/s 4,5, or 6. The belt surface is provided with projections 20 for gripping the cane/bagasse. Guide plate/s 21, may also be provided at the lower end of the belt conveyors 19.

The belts may be provided with perforations for separating out the superficial juice while compacting the well prepared cane/bagasse.

S. Juice extracted in various mill modules contains very fine particles of bagasse S* 15 known as cush-cush. The juice before being taken to boiling or further processing for making sugar is strained for separating out the cush-cush by passing over an in line strainer. The cush-cush soaked with juice alongwith over flow juice from the strainer, is fed into the mill module under the strainer for milling alongwith the bagasse. This high purity juice coming with cush-cush and recirculated through the 20 mill. creates extra slippage, juice over loading and poor juice drainage problem resulting into lower milling capacity and juice extraction efficiency.

Therefore, it was felt to separate out this rich juice from the cush-cush for further increasing the milling capacity and juice extraction efficiency with less power 25 consumption.of the improved cane crushing system of the present invention.

Now referring to figs. 10 to 14 the pressurized cush- cush juice extracting conveyor incorporated in the improved sugar cane milling system of the present invention comprises an open trough 22 having perforations 23 in its bottom. The open sides of the trough 22 are provided with support flanges 24. A screw 25 is InI provided inside the trough 22 and rotatably supported at two ends 26 27. The end 27 is provided with power transmission means such as gear 28. The perforated trough 22, at its bottom, is encased by a tray 29, having an outlet 30 for draining out the juice. The open trough 22 converges and forms an enclosed frustum of cone 31 towards the drive end 27 of the conveyor. The diameter of the screw 25 is also reduced according to the size of the frustum of cone 31.

The cush cush strained by the strainer (not shown), provided out of the center line of the mill tandem, is fed into the trough 22 of the conveyor as shown by arrow in fig. 14. The extra unabsorbed juice in the cush cush drips out through the perforated trough bottom into the tray 29, when the cush cush moves along the straight portion of the trough 22. Now when this cush -cush having absorbed juice only, enters the frustum of cone/converging portion 31 of the trough 22, it is pressed by the screw 25 against the enclosed trough casing and 15 most of the absorbed juice is also extracted out from the cush-cush which comes .out through the perforations provided all around in the frustum of cone portion 31 of the trough and the juice is collected in the tray 29 which is then drained out through the outlet 20 The screw'25 may also have reduced pitch alongwith reduced diameter in the converging portion 31 of the trough, The cush-cush having a little bit residual juice coming out of the cone portion 31 through its outlet .32 is fed to the mill module through the bottom opening 33 i25 provided towards the end 27,fig 14.

In case, fig 10, when the strainer is provided in-line with the center line of the mill tandem, the cush-cush with little bit residual juice, coming out of the cone portion 31, through its outlet 32 is fed to another screw conveyor 34 provided side by side of the first pressurized conveyor, described herein before. The lead of the screw of the second conveyor 34 is kept in opposite direction to the lead of screw and is rotated in the same direction with the help of pinion 36 and gear 37.

The second conveyor 34 brings back the cush-cush discharged from the first conveyor and feeds it in the mill module through the bottom opening 33 towards the end 26. The second conveyer 34 is having an open casing/trough 38 with support flanges 39 and without having any perforations in its trough 38.

The rich juice extracted out of the cush-cush according to the present invention described above, is collected from the outlet 30 of the tray 29 and is taken out without permitting it for recirculation through the mill module.

The main advantages of this are high purity juice re-circulation through the mill is avoided which reduces juice loading and slippage of mill module rolls.

It is clear from the above description that according to the present invention even a single toothed feeder roller with or without perforations and/or with or without scraper, provided in addition to and adjacent to one or more two or three roll mill modules in tandem, feeds the prepared cane/bagasse in compact form, without S 20 using a closed stationary pressure chute, almost at the same speed as of mill rolls and without sharp change in direction. The free superficial juice from the cane/bagasse is also removed when the toothed feeder roller is used with scraper or when toothed feeder roller is also provided with radial holes.

••25 The main advantages achieved by this invention are as follows I) The bulk density of cane/bagasse being fed to the mill is increased due to the positive grip of toothed feeder roller on cane/bagasse mat, giving significant increase in crushing rate with simple construction.

13- II) Feed to discharge operating opening ratio is reduced resulting in more juice extraction at the feed rolls and reduction in moisture percentage of the discharged bagasse which is used as fuel and thus achieves a high calorie value of fuel.

III) A higher rate of imbibition liquid, at higher temperature, to achieve extra sugar recovery from the bagasse, due to slip-free high grip over the bagasse mat.

IV) Lesser slippage allows reduction in mill speed thereby giving improved juice drainage and reduction in reabsorption of juice, further resulting in reduction of frictional losses and power consumption.

V) Fluent lifting of the top roll against hydraulic pressure due to reduction of feed to discharge operating opening ratio, brings the feed and discharge roll's resultant reaction near to vertical.

VI) Less wear and tear of various parts and hence low maintenance cost without needing very skilled personnel and low breakdown rates.

20 This problem troubled some closed stationary pressure chute, used ooo with a pair of toothed feeder rollers in poor art, has been dispensed with. The present invention gives trouble free continuous running for a longer time and gives high average output.

9 S: 25 It is therefore apparent that the present invention accomplishes the intended objects. The above description with reference to drawings is given just to understand the invention rather than to limit its scope.

9* Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims (2)

14- The Claims Defining the Invention are as Follows: 1. A sugar cane milling system comprising at least one toothed feeder roller with juice drainage means, the or each toothed feeder roller being provided in addition to and adjacent to a corresponding tandem mill module having at least two crushing rolls, the or each toothed feeder roller adapted to feed, when in use, a compact mat of prepared cane/bagasse directly to the nip of the crushing rolls of the module at substantially the same speed as the surface speed of the crushing rolls of the module and without a sharp change in direction. 2. A sugar cane milling system according to claim 1 wherein the or each toothed feeder roller comprises an outer shell and a plurality of individual teeth projecting from the outer shell in a desired pattern. 3. A sugar cane milling system according to claim 1 or claim 2 further comprising a scraper cum short deflector provided adjacent the outer shell of the or at least one of the toothed feeder rollers. 4. A sugar cane milling system according to claim 3 wherein the position of the scraper- cum short deflector is adjustable relative to the outer shell. t, A sugar cane milling system according to claim 3 or claim 4 wherein the juice drainage means comprises a gap between the scraper cum short deflector and the toothed feeder roller. A sugar cane milling system according to any one of claims 2 to claim 4 wherein the juice drainage means comprises radial holes or openings provided in the outer shell of the or each toothed feeder roller. 7. A sugar cane milling system according to claim 5 wherein the juice drainage 25 means further comprises radial holes or openings provided in the outer shell of the or each toothed feeder roller. 8. A sugar cane milling system according to any one of claims 1 to claim 7 comprising at least two toothed feeder rollers successively compacting the compact mat of prepared cane/bagasse being fed to the mill module. u S br~G 9. A sugar cane milling system according to any one of claims 1 to claim 8 further comprising a Donnelly chute having an exit end and positioned adjacent the feeder roller means for feeding the compact mat of prepared cane/bagasse to the feeder roller means and a pilot feeder means positioned in between the exit end of the Donnelly chute and the or the first toothed feeder roller for feeding the compact mat of prepared cane/bagasse to the or the first toothed feeder roller. A sugar cane milling system according to claim 9 wherein the pilot feeder means comprises a toothed or ribbed roller. 11. A sugar cane milling system according to claim 9 wherein the pilot feeder means comprises two toothed or ribbed rollers, positioned at opposing sides of the exit of the Donnelly chute. 12. A sugar cane milling system according to claim 9 wherein the pilot feeder means comprises a pair of belt conveyors provided at the exit end of the Donnelly chute, the pair of belt conveyors converging towards the feeder roller means. 13. A sugar cane milling system according to claim 12 wherein said pair of belts have perforations for separating out superficial juice while compacting the cane/bagasse. 14. A sugar cane milling system substantially as herein described.

15. A sugar cane milling system substantially as herein described with reference :o to the accompanying drawings. Dated this Twenty Second day of February 2001. BAPUSAHEB BHAURAO NIKAM Wray Associates Perth, Western Australia Patent Attorneys for the Applicant