AU2015201927B2 - A High Extraction Sugar Cane Crushing Mill - Google Patents

Abstract

A system for extracting juice from sugar cane or bagasse, the system including a pair of counter rotating pre-extraction rolls for crushing sugar cane or bagasse to form pre-crushed fibre and extract juice; and a pair of counter rotating extraction rolls for crushing pre-crushed fibre to extract a further amount of juice; wherein at least one of the counter rotating rolls in each pair has at least one peripheral juice channel extending about the roll and into which extracted juice can flow upon crushing; and, wherein the pre-crushed fibre formed by the pair of pre compression rolls is fed to the extraction rolls compressing the fibre to minimise fibres entering the at least one peripheral juice channel on the at least one of the counter rotating rolls. JUICE JUICE 24 DISCHARGE DISCHARGE JUICE JUICE DISCHARGE DISCHARGE BAGASSE DISCHARGE Figure 5

Description

A HIGH EXTRACTION SUGAR CANE CRUSHING MILL

TECHNICAL FIELD [0001] The present invention relates to an apparatus for crushing sugar cane to improve the drainage and separation of the sugar juice from the cane or bagasse.

BACKGROUND ART [0002] Sugar juice is removed from sugar cane by crushing the cane between crushing rollers. The cane is initially chopped into short lengths of about 20 - 50cm (called billets), or is shredded into a finely divided form. The billet or shredded cane is then crushed in a number of spaced apart mills.

[0003] A known type of mill is a three roll mill which consists of two bottom rolls next to each other and a top roll, the arrangement being that the centres of the roll shafts form a triangle. In this arrangement, a blanket of sugar cane or bagasse passes through the rolls in a generally horizontal or slightly inclined manner and juice is extracted during the crushing process.

[0004] Another known mill employs a pair of counter rotating rollers, one above each other such that the sugar cane moves horizontally between the rolls.

[0005] Sometimes, the mill has one or more additional rolls in front of the main crushing or primary rolls. The additional rolls are there to push a blanket of compressed sugar cane or bagasse to the main crushing rolls. In doing this, the additional rolls usually crush some juice from the cane or bagasse. Historically, this additional juice extraction was incidental and the primary function of these rolls is to force the cane or bagasse to the crushing rolls.

[0006] When sugar cane is crushed in a factory, the cane passes through a number of separate mills. Each mill consists of the above mentioned two, three, four or more roller arrangement. The sugar cane is conveyed from one mill to the next mill for further crushing.

[0007] A common feature of all current conventional mills is that the lower roll functions to drain most of the sugar juice from the feed material. This is primarily because of gravity effects causing the extracted sugar juice to move under the influence of gravity to the bottom roll. However, the top roll is also a crushing roll and extracted sugar juice also accumulates on top of the substantially horizontally moving blanket of cane of bagasse.

[0008] To remove this juice, openings are sometimes present in the top roll through which

2015201927 16 Apr 2015 the sugar juice can pass and drain from each end face of the roll. Such rolls are known as lotus rolls.

[0009] To improve the crushing efficiency of the cane or bagasse, it is known to groove both the top roll and the bottom roll to form a meshing-type effect.

[0010] For the bottom roll, it is known to cut additional juice grooves to a depth of about 25mm in each or every second or third groove in the roll to facilitate juice drainage. The juice grooves provide a path for the juice to flow away from the crush.

[0011] A disadvantage with established mill geometries is that the juice flows backwards against the direction of the roll. This counterflow of sugar juice against the roll surface movement is deleterious to the efficiency of juice removal. The forward flow of sugar cane or bagasse and the frictional resistance of the roll surface in contact with the juice retards the flow of juice. The retardation effect increases as roll surface speed increases. Therefore the possible benefits of juice grooves are limited by flow retardation and may be cancelled out altogether as surface speed increases to the point that counter flow of juice ceases and the juice is carried forward with the roll.

[0012] This effect also severely limits the capacity of the mill, as capacity is directly related to the roll length, roll diameter and roll speed ceteris paribus.

[0013] Increasing roll speed in conventional mills to above about 300mm per second can result in a sharp decline in extraction efficiency.

[0014] Attempts have been made to place deep penetrating scrapers into the grooves of the roll in order to remove bagasse, but this has the unfortunate consequence of encouraging the juice to be discharged with and reabsorbed by the bagasse which again results in a decline in extraction efficiency.

[0015] When sugar cane is conveyed from one mill to the next mill, the cane blanket tends to expand as it is discharged from one mill and before it gets compressed and crushed by the next mill.

[0016] In order to improve the efficiency of the sugar juice extraction in the next mill, it is known to add water, or dilute juice to the sugar cane blanket as it expands, this process being known as imbibition or “maceration”.

[0017] A disadvantage with adding water, or dilute juice at this stage in a two roll mill is

2015201927 16 Apr 2015 that the sugar cane blanket is also required to be in a semi-compressed form. Pressure chutes are therefore positioned between each crushing stage. The pressure chutes maintain the sugar cane blanket or bagasse in a semi-compressed form as a consequence of the driving force necessary to transfer the bagasse to the next stage where the bagasse is transferred horizontally.

[0018] However, by maintaining the bagasse in a semi-compressed form, it does not fully expand and therefore imbibition is not totally successful.

[0019] When imbibition liquid is added to the semi-compressed bagasse, not only does the bagasse not absorb as much liquid as is possible if the bagasse was not maintained in a semicompressed system, but because the bagasse is conveyed along a horizontal or slightly inclined angle, the imbibition liquid is sprayed or added to the top of the bagasse blanket and does not easily permeate through the blanket. It is generally not possible to spray or apply liquid to the bottom of the bagasse blanket as gravity effects will cause the spray or liquid to simply fall away and not be absorbed.

[0020] Another disadvantage with existing mills is the deleterious effect of upflow of sugar juice against the downflow movement of the sugar cane. For example, in the conventional three roll mills or the two roll mills where one roll is above the other roll, the sugar cane or bagasse moves along a generally horizontal pathway (although the pathway may be slightly inclined in particular areas) . With the large pressures being exerted on the sugar cane between the crushing rolls, it is found the sugar juice has a tendency to move upward on to the face of the rolls and is therefore not efficiently separated from the cane. The upflow of juice also reduces the grip of the rolls on the bagasse by making the rolls slippery. The effect is a result of the substantially horizontal movement of the sugar cane or bagasse through the mill.

[0021] Another disadvantage with the current mill arrangement is that if any pair of rolls has a mechanical fault, the entire crushing unit must stop operating as the defective stage cannot be bypassed.

[0022] Another disadvantage with existing mill arrangements is that the supply end of a pair of rolls has a fairly small feed zone which is the cross-section area where the bagasse begins to be pulled in by the rolls. It is desirable to have the feed zone as large as possible over which sugar cane or bagasse will self-feed into the rolls. Feed rolls are known to increase the crosssectional area of the feed zone but add significantly to the cost of the equipment.

[0023] Another disadvantage with conventional mills is their high power consumption due to the large number of rolls required to provide an acceptable level of juice extraction along with

2015201927 16 Apr 2015 the stationary plates and chutes used to convey material from one pair of rolls to the next.

[0024] Much attention has also been given to the design and manufacture of the crusher roll used in crushing sugar cane.

[0025] Crusher rolls are extremely well-known in the sugar cane industry and are widely used in sugar cane crushing mills to extract sugar cane juice from sugar cane, prior to clarification, evaporation and crystallisation of the sugar from the juice.

[0026] Much research and development has been undertaken to improve the efficiency of sugar juice extraction from the cane. The efficiency is measured in the power consumption required to drive the crusher rolls, the throughput of the sugar cane, and the extraction efficiency of the sugar juice from the cane.

[0027] It is known that the extraction efficiency can be improved by grooving the periphery of the crusher rolls, and by providing juice discharge channels behind the periphery. Examples of such rolls are found in the patent literature and the following patent documents exemplify the current rollers - Australian Patent Applications 74784/81, 84046/82, 34686/84, 10914/88; U.S. Patents 3,536,002, 4,077,316, 4,220,288, 4,378,253, 4,168,660, 4,420,863, 4,804,418; United Kingdom Patent Application 2,025,260; French Patents 2,251,622, 2,569,608; German Patents 2,716,666, 2,657,232, 3,427,418.

[0028] The juice channels extend longitudinally inside the roll and just behind the peripheral or crushing surface of the roll. The juice channels are normally relatively small diameter tubes formed in the roll. These tubes are in fluid communication with the surface of the roll as is known in the art, and the function of the juice channels is to improve the separation of the liquid from the material to be crushed. The juice channels do not join each other and a fairly large number of parallel extending separating juice channels extend entirely around the roll.

[0029] The juice channels in turn communicate with an outlet such that juice can flow through the channel and into the outlet where in turn it is carried away for further processing. The outlet can be associated with a valve if desired. Outlets can be provided on both side faces of the roller, or on only one side face. The outlets are in sliding but sealing engagement with the side face of the roller such that as the roller rotates, the separate juice channels pass along the outlet to drain the juice. It is possible for the outlet to extend entirely around the roller, but it is more common for the outlet to extend only along a portion of the side face of the roller, this portion of course being where the juice passes into the juice channels.

2015201927 16 Apr 2015 [0030] It is known that crushing efficiency is improved by increasing the diameter of the rolls. However, the design and geometry of conventional 3, 4, 5 and 6 roll mills constrains the diameter of the rolls to about one half the length of the roll. This diameter to length ratio has been found to offer a reasonable compromise between capacity, strength, extraction efficiency and roll weight.

[0031] The conventional thinking and teaching to improve the efficiency of the roller is by changing the peripheral groove shape, providing drainage channels in the roller, providing back pressure to the roller, and reducing the gap between the rollers.

[0032] The Applicant has had some previous success increasing the crushing efficiency in this way by way of the invention described in Australian Patent No. 1997026281. Australian Patent No. 1997026281 discloses an apparatus for extracting juice from sugar cane having a pair of counter rotating rolls between which the cane is crushed. At least one of the rolls having a peripheral juice channel extending about the roll and into which sugar juice can flow. The channel being configured such that in use a sealing plug of bagasse forms in an upper portion of the channel with a lower portion of the channel left free for holding the juice. The apparatuses further including a bagasse plug removing means to remove the plug of bagasse to allow the juice to drain from the channel at a position where the juice does not contact the crushed cane blanket. However, further increases in efficiency in crushing sugar cane are continuously desired.

[0033] It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.

SUMMARY OF INVENTION [0034] The present invention is directed to an apparatus for crushing sugar cane or bagasse to extract the juice therefrom, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice.

[0035] With the foregoing in view, the present invention in one form, resides broadly in a system for extracting juice from sugar cane or bagasse, the system including:

at least a pair of counter rotating pre-extraction rolls for crushing sugar cane or bagasse to form pre-crushed fibre and extract juice; and at least a pair of counter rotating primary extraction rolls for crushing pre-crushed fibre to extract a further amount of juice;

2015201927 16 Apr 2015 wherein at least one of the counter rotating rolls in each pair has at least one peripheral juice channel extending about the roll and into which extracted juice can flow upon crushing; and wherein the pre-crushed fibre formed by the pair of pre-extraction rolls is fed to the primary extraction rolls further compressing the fibre to minimise fibres entering the at least one peripheral juice channel on the at least one of the counter rotating rolls.

[0036] The pre-extraction rolls can be of various diameters and lengths, and can be made from various materials, a typical material being cast iron. Hard facing or one or more wear resistant formations may be provided on one or both rolls. Preferably, the pre-extraction rolls are cylindrical in shape and of similar diameter and length to one another.

[0037] The pre-extraction rolls are typically in a side by side relationship with the axis of rotation being horizontal such that the sugar cane or bagasse passes between the pre-extraction rolls in a substantially vertical direction.

[0038] Each pair of pre-extraction rolls typically rotates in a counter rotating motion. Preferably, each pre-extraction roll rotates inward towards the other pre-extraction roll such that the sugar cane or bagasse is moved towards and through the middle of each pair of the preextraction rolls.

[0039] Each of the pre-extraction rolls is optionally driven by a separate drive arrangement. Alternatively, a pair of pre-extraction rolls is driven by a single drive arrangement.

[0040] The pre-extraction rolls are typically spaced apart such that the pre-extraction roll surfaces can crush sugar cane or bagasse in a crushing region between the rolls as the preextraction rolls counter rotate. One or both of the pre-extraction rolls may be grooved or have other formations to facilitate or improve crushing or crushing efficiency. Preferably, the grooves of one pre-extraction roll are offset from the groove of the other pre-extraction roll in each pair of rolls.

[0041] Preferably, the sugar cane or bagasse enters the crushing region between the preextraction rolls from a supply end located above the pre-extraction rolls and exits at a discharge end located below the pre-extraction rolls and adjacent a crushing region between the primary extraction rolls. Preferably, the pre-crushed fibres are discharged in a semi-compressed sheet in which the fibres, particularly smaller fibres, are already at least partially contained in a mat form.

[0042] At least one of the pre-extraction rolls includes at least one juice channel to collect

2015201927 16 Apr 2015 the juice as the sugar cane or bagasse is crushed between the pre-extraction rolls. Preferably, both pre-extraction rolls include a plurality of spaced apart, substantially parallel juice channels over their length for collecting juice. Preferably, the juice channels of one pre-extraction roll are offset from the juice channels of the other pre-extraction roll.

[0043] It is preferred that the juice channels extend circumferentially around the preextraction roll to facilitate entry of juice into the juice channel and discharge of juice from the channel.

[0044] The juice channel may be of any cross-section shape. One type of juice channel may be bottle-shaped having a narrower necked portion in the base of the groove in the roll, opening up into a larger channel portion. The necked portion may facilitate in restricting or preventing cane or cane fibre from passing into the juice channel.

[0045] Preferably, the juice channel may be substantially U-shaped with parallel side walls, the channel having a depth larger than the grooves in a conventional roll. Sugar cane may pass over the top or partially into the channel but does not entirely fill the channel to form a partially compressed mat formation.

[0046] Preferably, at least one of the pre-extraction rolls may be grooved in a conventional manner with apertures being formed in the bottom of the groove. The apertures communicating with an internal juice channel to convey juice away from the crush zone between the preextraction rolls.

[0047] Similar to the pre-extraction rolls, the primary extraction rolls can be of any diameters and lengths, and can be made from any material(s), a typical material being cast iron. Hard facing or one or more wear resistant formations may be provided on one or both rolls. Preferably, the primary extraction rolls are cylindrical in shape and of similar diameter and length to one another and/or the pre-extraction rolls.

[0048] The primary extraction rolls are typically in a side by side relationship with one another with the axis of rotation being horizontal such that the pre-crushed fibre passes between the primary extraction rolls in a substantially vertical direction. Preferably, the pre-crushed fibres enter a crushing zone or region between the primary extraction rolls at an upper, supply end and are discharged at a lower discharge end.

[0049] The primary extraction rolls are located relatively below the pre-extraction rolls. Preferably, the axes of rotation of the primary extraction rolls vertically align with the axes of

2015201927 16 Apr 2015 rotation of the pre-extraction rolls above such that the pre-crushed fibre passes from the discharge end of the pre-extraction rolls to the supply end of the primary extraction rolls. Advantageously, in this arrangement, the pre-extraction rolls crush the sugar cane or bagasse into pre-crushed fibre and further, preferably at least partially compact the fibre into a mat or plug which minimises the number of stray fibres available to enter the juice channels located on the primary extraction rolls.

[0050] Similar to the pre-extraction rolls, the primary extraction rolls typically rotate in a counter rotating motion. Preferably, each primary extraction roll rotates inward towards the other primary extraction roll such that the pre-crushed fibre is moved towards and through the middle of the pair of the primary extraction rolls. Preferably, the primary extraction rolls rotate at the same revolutions per minute as the pre-extraction rolls. Alternatively, the primary extraction rolls rotate at the same angular velocity as the pre-extraction rolls. Alternatively again, the primary extraction rolls may rotate at a faster or slower revolutions per minute or angular velocity in comparison to the pre-extraction rolls.

[0051] Each of the primary extraction rolls is optionally driven by a separate drive arrangement. Alternatively, a pair of primary extraction rolls is driven by a single drive arrangement.

[0052] Similar to the pre-extraction rolls, the primary extraction rolls are typically spaced apart such that the primary extraction roll surfaces can crush the pre-crushed fibre as the primary extraction rolls counter rotate. Preferably, the primary extraction rolls are spaced apart at a distance smaller than the spaced apart distance of the pre-extraction rolls in order to facilitate further compression of the pre-crushed fibre and to facilitate further juice extraction.

[0053] One or both of the primary extraction rolls may be grooved to facilitate crushing and/or juice collection.

[0054] At least one of the primary extraction rolls includes at least one juice channel to collect the juice as the pre-crushed fibre is crushed between the primary extraction rolls. Preferably, both primary extraction rolls include a plurality of circumferentially extending, substantially parallel juice channels.

[0055] Preferably, the shape of each primary extraction roll juice channel is similar to the shape of each juice channel of the pre-extraction rolls. Alternatively, the primary extraction roll juice channel(s) may be of a larger depth in order to facilitate extraction of a larger quantity of juice.

2015201927 16 Apr 2015 [0056] Similar to the pre-extraction rolls, the primary extraction rolls may be grooved in a conventional manner with apertures being formed in the bottom of the groove the apertures communicating with an internal juice channel to convey juice away from the crush zone between the primary extraction rolls.

[0057] Optionally, the system further includes at least one additional pair of counter rotating rolls. Preferably, any additional pair of rolls is of the type described in relation to the preextraction rolls or primary extraction rolls above.

[0058] Preferably, the pre-extraction rolls, primary extraction rolls and any additional pairs of rolls form a tower arrangement. It is preferred that any additional pair of counter rotating rolls could act as a pair of pre-extraction rolls for a pair of following counter rotating primary extraction rolls and as a pair of primary extraction rolls for a pair of counter rotating preextraction rolls. In other words, a second pair of rolls may be primary extraction rolls in relation to a pair of pre-extraction rolls and may function as a pair of pre-extraction rolls for a following set of primary extraction rolls.

[0059] Optionally, each pair of rolls can be associated with feeder rolls, chutes, feeders or other devices which can increase the density of the pre-crushed fibre in the feed zone.

[0060] Optionally, juice guards can be associated with any one or more of the rolls in order to contain the extracted juice until the juice can exit the juice channel(s).

[0061] Optionally, juice groove scrapers can be associated with any one or more of the rolls. Preferably, scrapers are located relative to at least the rolls having juice channels. Preferably a scraper is provided for each channel. Advantageously, the scrapers remove the pre-crushed fibre from the juice channels of the rolls such that the juice contained within the juice channels can be drained away from the rolls.

[0062] Optionally, juice drains can be associated with any one or more of the rolls. Preferably, juice drains are located relative to rolls having juice channels. Advantageously, the extracted juice can be collected from the juice channels and moved away from the rolls.

[0063] Optionally, one or more chutes can be associated with each pair of rolls. Preferably, a pre-crushed fibre chute is located immediately after the discharge end of the pre-extraction rolls and extends toward the supply end of the primary extraction rolls in order to aid the transportation of the pre-crushed fibre from the pre-extraction rolls to the primary extraction rolls. In addition, an extraction chute may be located immediately after the discharge end of the ίο

2015201927 16 Apr 2015 primary extraction rolls in order to aid transportation of the crushed fibres away from the primary extraction rolls.

[0064] Any of the features described herein can be combined in any combination with any one or more of the other features described herein within the scope of the invention.

[0065] The reference to any prior art in this specification is not, and should not be taken as an acknowledgement or any form of suggestion that the prior art forms part of the common general knowledge.

BRIEF DESCRIPTION OF DRAWINGS [0066] Preferred features, embodiments and variations of the invention may be discerned from the following Detailed Description which provides sufficient information for those skilled in the art to perform the invention. The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

[0067] Figure 1 is a longitudinal cross-section of a mill roll according to a first embodiment.

[0068] Figure 2 is a longitudinal cross-section of a mill roll according to a second embodiment.

[0069] Figure 3 is a section view of a mill roll according to a third embodiment attached to a shaft.

[0070] Figure 4 is an end view of the mill roll of Figure 2.

[0071] Figure 5 is a schematic drawing of a preferred embodiment of the present invention.

[0072] Figure 6 is a front sectional view of a preferred embodiment of the invention.

[0073] Figure 7 is a front view of a preferred embodiment of the invention.

[0074] Figure 8 is a side sectional view of a preferred embodiment of the invention.

[0075] Figure 9 is a top view of a preferred embodiment of the invention.

DESCRIPTION OF EMBODIMENTS [0076] Referring to the figures and initially to Figures 1-3, there is shown a longitudinal

2015201927 16 Apr 2015 cross-section of a single roll in accordance with embodiments of the present invention.

[0077] Figure 1 illustrates a roll consists of parallel circular plates 1 mounted on a central shaft 2 by any conventional means. The plates are shaped to form an angled full circumference groove 8 which converges to a narrow full circumference slot 5 radially in and then diverges to a wider full circumference channel 6. The channel 6 intersects axial holes 9. A hard, rough coating 7 may be deposited on the tip and flank of the angled grooves. In operation, the juice-laden cane fibre is forced into the grooves by the opposing horizontal roll. Tightly compacted cane fibre is restricted to the angled groove portion 8. Juice is free to flow radially in and down through the full circumference channel and out through the radial holes. In practice the path of least resistance is down and virtually no juice flows through the axial holes.

[0078] Further, Figure 2 illustrates the longitudinal cross-section of a second form of a crusher roll that is less costly to manufacture, is easier to clean, and offers improved juice drainage. The roll may be made of one or more pieces 10 of solid cast iron, SG iron, steel or other suitable material in the form of a shell suitably fastened to a central shaft 12. Full circumference angled grooves 13 are formed in the shell. Full circumference parallel channels 14 are formed in the base of each groove. In operation, cane fibre is tightly compacted into the angled grooves 13 and the outer portion of the parallel channels 14 by the action of the horizontally opposed other roll. Juice is free to move radially in to and down through the parallel juice channels 14 and to exit from the base of the roll.

[0079] Furthermore, Figure 3, illustrates a mill roll 50 made from cast iron and which is mounted to a rotatable shaft 52. The roll is mounted for non-rotational movement relative to shaft 52.

[0080] The roll has a hub portion 51, an outwardly extending web portion 56 which has a thickness considerably less than hub portion 51, and a rim portion 57. Rim portion 57 is formed with grooves 53 of the type which are known in the art. Rim portion is formed with perforations and/or slots which communicate with a longitudinal juice channels 54 to carry away extracted juices.

[0081] It can be seen that the roll has two large weight-reducing annular voids 58 which exist because of the relative thin walled construction of web portion 56. These voids considerably reduce the weight of the roll which in turn allows the roll to be considerably longer than hitherto practical, or allows the roll to have a much larger diameter than hitherto practical.

[0082] Figure 4 illustrates the axial cross-section of roll 10 through the mid-plane of one of

2015201927 16 Apr 2015 the full circumference angled groove and parallel juice channels. The cross-section of scrapers and a juice collector is also shown. The scraper moves crushed fibres from the angled groove 13 and the outer portion of the parallel juice channel 14. Blades 15 are positioned so that the leading tips of the blades penetrate the parallel juice channel 14 deeper than the compacted cane fibre. As the roll and cane fibres move downwards, the blades 15 pushes a majority of the cane fibres out of the groove and into a discharge chute. Some tightly compacted cane fibres may be left behind. Juice is free to drain down the full circumference channel 14 to the base of the roll to discharge into juice collectors 16. The blades 15 are slightly thinner than the width of the parallel juice channel 14. The blades 15 are supported by a plate 17 that has an angled top to direct loose cane fibre into the cane fibre discharge chute.

[0083] Turing to Figure 5, Figure 5 shows a schematic drawing of the preferred embodiment of the present invention. Sugar cane billets, crushed cane, or shredded cane are fed into a pair of opposed counter rotating pre-extraction rolls 21, 22 via a feed arrangement. Juice and precrushed cane fibre are discharged separately. The pre-crushed cane fibre is then fed into a pair of opposed counter rotating primary extraction rolls 23, 24. Again, juice and crushed cane fibre are discharged separately. Preferably, the crushed cane is bagasse.

[0084] Referring to Figure 6, there is illustrated a mill 20 in accordance with an embodiment of the present invention. Mill 20 consists of a pair of upper opposing counter rotating preextraction rolls 21, 22 that define a width between which sugar cane or bagasse (not shown) passes and is crushed.

[0085] Each pre-extraction roll 21, 22 may be of varying types but preferably are the rolls of figures 1 to 3.

[0086] Each pre-extraction roll comprises a longitudinal axis. The longitudinal axis of each pre-extraction roll aligns with the other such that the pre-extraction rolls are located in horizontal alignment with one another.

[0087] Sugar cane billets, crushed cane, shredded cane or cane fibres are fed into the preextraction rolls 21, 22 by a conventional feed hopper (not shown) at an upper input end and exits at a lower discharge end as pre-crushed cane fibre.

[0088] Each pair of pre-extraction rolls 21, 22 is driven by a separate drive arrangement.

[0089] As best can be seen in Figure 9, the channels of each pre-extraction roll are offset from one another to facilitate crushing of the sugar cane.

2015201927 16 Apr 2015 [0090] Mill 20 further includes a pair of pre-extraction roll juice primary juice scrapers (not shown). The primary juice scrapers are located at the discharge end of the pre-extraction rolls 21, 22. The primary juice scrapers facilitate at least partially remove of the pre-crushed fibre from the surface of the pre-extraction rolls such that the pre-crushed fibre discharged by the preextraction rolls, feeds into chute 46 for transport to primary extraction rolls 23, 24 located below, as described in relation to Figure 4 above.

[0091] Mill 20 further includes a pair of pre-extraction roll juice secondary scrapers 30, 31. The secondary scrapers are located towards the outer side of each pre-extraction roll 21, 22 above respective juice collectors 34, 35 and facilitate removal of any remaining pre-crushed fibre from inside of the juice channels such that the remaining pre-crushed fibre and juice from the juice channels is discharged into the juice collector 34, 35 located below for collection.

[0092] Mill 20 further includes a pair of pre-extraction roll juice collectors 34, 35 and a pair of juice collection points 40, 41. Each juice collector includes a juice tray 36, 37 and a juice drain 38, 39. Each juice tray 36, 37 is conical in shape in order to facilitate draining juice away from the pre-extraction rolls 21, 22. Each juice tray 36, 37 comprises a large upper opening 34a, 35a for collecting extracted juice from the pre-extraction rolls and a smaller lower discharge end 34b, 35b to facilitate the flow of juice in a downward direction and towards the juice collection point 40, 41. Each juice drain 38, 39 is an elongate chute having an upper input end 38a, 39a and a lower output end 38b, 39b. Each upper input end 38a, 39a is located relative the lower discharge end of the juice tray 34b, 35b in order to further facilitate the flow of juice away from the pre-extraction rolls 21, 22 and towards the juice collection point 40, 41. Preferably, the juice collection points are located towards the bottom of mill 20.

[0093] Mill 20 further includes a pair of horizontal pre-extraction roll juice splash guards 42, 43. Each splash guard 42, 43 is typically an elongate shape. However, could be of any shape necessary. The splash guards 42, 43 are located on the outer side of each a pre-extraction roll 21, 22 such that juice being extracted from the juice channels is directed toward the associated preextraction roll juice collector 34, 35.

[0094] Mill 20 further includes an upper pre-crushed fibre chute 46 and a pair of lower opposing counter rotating lower primary extraction rolls 23, 24 to which the upper chute feeds the discharged pre-crushed fibre from the pre-extraction rolls.

[0095] The pre-crushed fibre chute 46 is located relative to the pre-extraction rolls 21, 22 and primary extraction rolls 23, 24. The pre-crushed fibre chute 46 includes an input end 46a

2015201927 16 Apr 2015 located relative to the discharge end of the pre-extraction rolls and a discharge end 46b located relative to an input end of the lower primary extraction rolls. Preferably, the pre-crushed fibre chute 46 is narrower at the input end and wider at the output end to allow expansion of the precrushed fibre prior to entering the primary extraction rolls and to facilitate flow of the precrushed fibre from the pre-extraction rolls 21, 22 toward the primary extraction rolls 23, 24.

[0096] Each primary extraction roll 23, 24 may be of varying types but preferably are the drainage rolls of figures 1 to 3. Preferably still, the primary extraction roll 23, 24 are of the same type as the pre-extraction rolls 21, 22. The primary extraction rolls 23, 24 are preferably of similar diameter and length to the pre-extraction rolls 21, 22 but maybe smaller or larger, or longer or shorter.

[0097] Each primary extraction roll 23, 24 includes juice channels for facilitating removal of juice from the crush cane fibres. As the primary extraction rolls rotate the pre-crushed cane fibre enters the primary extraction rolls via an upper inlet to be crushed. Mill 20 further includes a pair of juice guides 44, 45. Each juice guide is typically sloped downwardly in order to facilitate drainage of extracted juice away from the primary extraction rolls 23, 24 and towards the juice collection points 40, 41. Each juice guide includes guards either side to prevent juice from escaping the guide and a discharge end. Each juice guide is located relative to a primary extraction roll 23, 24 such that juice discharged from the primary extraction rolls drain into the juice guide.

[0098] Preferably, the discharge end of each juice guide 44, 45 is located relative to the juice collection point such that juice exits the juice discharge end and into the juice collection point.

[0099] Mill 20 further includes a pair of primary extraction roll juice primary scrapers (not shown). The primary scrapers are located at the discharge end of the primary extraction rolls. The primary scrapers scrape crushed cane fibre from the channels of the primary extraction rolls 23, 24 such that the crushed fibres drop down a lower chute for crushed cane fibre below, as described in relation to Figure 4 above.

[0100] Mill 20 further includes a pair of primary extraction roll juice secondary scrapers 48, 49. The secondary scrapers are located towards the outer side of each primary extraction roll 23, 24 above respective juice collectors and facilitate removal of any remaining crushed fibre from inside of the primary extraction roll juice channels such that the remaining crushed fibre and juice from the juice channels falls into the juice collector located below for collection.

[0101] Mill 20 further includes a lower crushed cane fibre chute 47 for facilitating the

2015201927 16 Apr 2015 transfer of crushed cane fibre away from the primary extraction rolls 23, 24 and towards a crushed cane fibre collection point below (not shown). The lower crushed cane fibre chute 47 comprises a localised converging section at the upper end for assisting the formation of a plug formation to prevent juice from draining out of juice channels and into the crushed cane fibre collection point.

[0102] In the present specification and claims (if any), the word ‘comprising’ and its derivatives including ‘comprises’ and ‘comprise’ include each of the stated integers but does not exclude the inclusion of one or more further integers.

[0103] Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0104] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Claims (19)

1. A system for extracting juice from sugar cane or bagasse, the system including:

at least a pair of counter rotating pre-extraction rolls for crushing sugar cane or bagasse to form pre-crushed fibre and extract juice; and at least a pair of counter rotating primary extraction rolls for crushing pre-crushed fibre to extract a further amount of juice;

wherein at least one of the counter rotating rolls in each pair has at least one peripheral juice channel extending about the roll and into which extracted juice can flow upon crushing;

wherein the pre-crushed fibre formed by the pair of pre-extraction rolls is fed to the primary extraction rolls compressing the fibre to minimise fibres entering the at least one peripheral juice channel on the at least one of the counter rotating rolls.

2. A system for extracting juice from sugar cane or bagasse as claimed in claim 1, wherein the pre-extraction rolls are arranged such that the cane fibre passes between each pre-extraction roll in a substantially vertical direction.

3. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the primary extraction rolls are arranged such that the pre-crushed fibre passes between each extractor roll in a substantially vertical direction.

4. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the width between the pre-extraction rolls is larger than the width between the primary extraction rolls.

5. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims wherein the at least one juice channel is substantially U-shaped with parallel side walls, the channel having a depth larger than the grooves in a conventional roll.

6. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims further including at least one scraper for removing fibre from the at least one juice channel such that the juice contained within the at least one juice channel can be drained from the roll.

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7. A system for extracting juice from sugar cane or bagasse as claimed in claim 6, wherein the at least one scraper further includes at least one blade.

8. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the system further includes at least one juice collector for collecting juice from the pre-extraction rolls.

9. A system for extracting juice from sugar cane or bagasse as claimed in claim 8, wherein the at least one juice collector includes a juice tray and a juice drain for facilitating the flow of juice away from the pre-extraction rolls and toward a collection point.

10. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the system further includes at least one juice guide for collecting and guiding juice away from the primary extraction rolls.

11. A system for extracting juice from sugar cane or bagasse as claimed in claim 10, wherein the at least one juice guide is sloped in a downward direction for draining juice away from the primary extraction rolls and toward a collection point.

12. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the system further includes at least one splash guard.

13. A system for extracting juice from sugar cane or bagasse as claimed in any one of claims 8 to 12, wherein the splash guard is located on an outer side of at least one pre-extraction roll.

14. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the system further includes an upper chute for facilitating the removal of pre-crushed fibre away from the pre-extraction rolls and directing that fibre towards the primary extraction rolls.

15. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the system further includes a lower chute for facilitating the removal of crushed fibre away from the primary extraction rolls.

16. A system for extracting juice from sugar cane or bagasse as claimed in claims 14 or claim 15, wherein at least one chute is narrower at an upper end and wider at a lower end of the chute.

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17. A system for extracting juice from sugar cane or bagasse as claimed in any one of claims 14 to 16, wherein at least one chute comprises a localised converging portion for assisting the formation of a plug formation.

18. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, wherein the crushed fibre is higher in bulk density than the pre-crushed fibre.

19. A system for extracting juice from sugar cane or bagasse as claimed in any one of the preceding claims, the system further including at least one additional pair of counter rotating rolls, wherein the additional pair of counter rotating rolls acts as a pair of pre-extraction rolls for a pair of counter rotating primary extraction rolls and acts as a pair of primary extraction rolls for a pair of counter rotating pre-extraction rolls.