WO2018160056A2

WO2018160056A2 - System for continuous extraction of pericarp liquid and method thereof

Info

Publication number: WO2018160056A2
Application number: PCT/MY2018/050007
Authority: WO
Inventors: Gregory L FOSTER; Robiah Yunus
Original assignee: Foster Gregory L; Robiah Yunus
Priority date: 2017-03-03
Filing date: 2018-02-28
Publication date: 2018-09-07
Also published as: WO2018160056A3

Abstract

The present invention relates to a system and method for continuous extraction of liquid from pericarp of fruit like oil palm fruit. The system comprises a first compression conveyor screw (100) configured for processing the pericarp along a feeding and compression zone defined thereof comprising a conical shaft (101) and a plurality of helical screw flights (102) formed thereon, wherein each of the plurality of helical screw flights (102) has a variable pitch and a variable flight depth that decreases in a proximal direction extending along the conical shaft (100); a second compression conveyor screw (200) configured for processing the pericarp conveyed from the first compression conveyor screw (100) along a compression and metering zone defined thereof comprising a disk-shaped member (201) and a perforated pressure plate (202) coupled to the disk-shaped member (201) for releasing the liquid from the pericarp compressed thereof therethrough.

Description

SYSTEM FOR CONTINUOUS EXTRACTION OF PERICARP LIQUID AND

METHOD THEREOF

FIELD OF THE INVENTION

The present invention relates generally to arrangement for processing fruits that comprised of kernel nuts and the pericarp. More particularly, the present invention relates to a system and a method for extracting liquid from the pericarp surrounding the kernel nut of a fruit, especially the oil palm fruitlets.

BACKGROUND OF THE INVENTION

The mass of a fruit is comprises of seed or nut and a pericarp which is usually made up of three distinct layers, namely the epicarp which is the outermost layer, the mesocarp which is the middle layer and the endocarp which is the inner layer surrounding the ovary of the seed. The extraction of liquids namely water, juice or oil are typically removed from the fleshy pericarp by way of applying pressure on a batch or continuous basis. Several methods including, spinning, batch hydraulic pressing and continuous screw pressing are used commercially to mechanically rupture the cell wall and liberate the liquid from the pericarp.

Figure 1 shows a typical continuous pressing which remains as a preferred method, where it relies on a single or double longitudinally rotating helical screw to convey, compress and meter the agricultural mass input to squeeze the oil entrapped within the pericarp. The screw is typically divided into three zones: feeding, compression and metering. This continuous process can be used for removing oil from oil-accumulating fruit, beans and seeds such as oil palm fruit, olive fruit and soybeans. Oil residing within the fleshy pericarp tissue accumulates in accordance with the morphology unique to the mass and can be efficiently removed by applying pressure. However, the presence of a nut or seed in the fruit directly affects the parameters of the process vis-a-vis throughput, oil residue on fibre and nut/seed breakage. The effectiveness of continuous screw pressing for extracting palm oil is limited because the "mash" (a mixture of oil, water, fibre and kernel nut produced in a digester) is fed to the screw press inclusive of the kernel nut. The digested mash enters the press at the feeding zone. At the point of entry to the feeding zone, the volume ratio pericarp to nuts is approximately 1 .5:1 . As the screw helix causes the mash to progress to the compression zone and then on to the metering zone, oil water and non-oil-solids (NOS) are expelled due to the pressure exerted by the screw flight face and the reduction in volume due as the depth of the screw flight as illustrated in Figure 2 which progressively reduce through the compression zone.

However, the presence of kernel nuts in the digested mash limits the amount of pressure that can be applied at the metering zone and demands that the volume or space between successive flight pitches of the screw is sufficient to allow for the mesocarp fibre to be compressed to expel oil before kernel nuts begin to break due to the applied pressure. The volume of mash between successive screw flights is determined by the screw helix, i.e. the distance the mesocarp and kernel nuts can be conveyed in one revolution, times the depth of the flight, i.e. the distance between the root radius and the outer radius of the screw, times the width of the screw flight, see Figure 3.

The throughput volume of one revolution can only be increased by increasing one or several of the parameters, i.e. screw flight depth, screw width, screw helix and/or rotation per minute (RPM). The efficiency of the continuous screw press is limited by the constraints of the described parameters. A variation of one parameter may positively affect one condition but adversely affect another. None the less, it is possible to increase throughput by increasing the RPM, helix angle, pitch, flight depth or any combination described but any variation from the optimum condition causes excessive oil loss on dry fibre - as high as 1 % of fresh fruit bunches (FFB) throughput tonnes. For example, restricting the force exerted on the fibre reduces nut breakage but causes excessive crude palm oil loss due to a lack of compression on the mesocarp fibre. Increasing the RPM results in a higher throughput but allows insufficient residency time for the oil to find its way through the flight depth to the perforated outer cage. To illustrate the point, when manufacturers doubled the screw flight depth from 50mm to 90mm to achieve a throughput capacity from 9 tonnes of FFB/h to 15 tonnes of FFB/h, it is well documented in sales literature and research material that this increase in flight depth concurrent with an increase in RPM negatively impacted the oil lost on dry fibre from 4% to 8%.

The most significant limitation of the conventional continuous horizontal screw press for extracting palm oil from sterilised fruit is not the volumetric throughput capacity of the press but the high Crude Palm Oil (CPO) losses and Palm Kernel Oil (PKO) losses due to the presence of kernel nuts. Once the mesocarp fibre is compressed by the screw to equal the volume occupied by the kernel nuts (the equilibrium point), marginal pressure increases thereafter in pursuit of maximising oil extraction will result in the destruction of kernel nuts.

Continuous pressing is therefore limited by these two extremes. On one hand, too much pressure results in nut breakage (as high as 15% of fruit throughput), while on the other hand, too little applied pressure results in too much oil (as high as 1 % of the total FFB processed) being discarded with the mesocarp fibre. However, despite the high oil losses associated with the traditional continuous pressing method the process remains as the preferred method.

A number of post-processing methods have been explored to reduce the losses associated with the continuous pressing method. These include, adding mesocarp fibre to the digested mash to increase the ratio of fibre relative to nuts to change the equilibrium point as described or washing the mesocarp fibre expelled from the mesocarp after the kernel nut have been separated in hot water or removing the kernel nuts from the expelled mesocarp fibre or subjecting the expelled mesocarp to a second pressing. However, all of the described post processing methods have limitations. For example, adding mesocarp fibre has recorded incremental improvements in oil extraction but the process slows the rate of throughput and is cumbersome to execute. Washing the fibre in hot water does recover some of the lost oil but has failed to find traction as a process due to the handling and capital cost. Double pressing involves re-pressing the mesocarp fibre after separating the mesocarp fibre from the kernel nuts. Trials conducted on second pressing of mesocarp conclusively reduced the oil remaining on the fibre, however double pressing is not widely practiced because of the additional material handling involved and separating small fragments of solid mesocarp, i.e. NOS which also break away and enter the oil due to the severe torsional stresses imposed on the fibre by the co-axial press requires an additional centrifuge operation.

A need therefore exists for an improved system and method that is suitable where the fruit, nut or bean volume is entirely made up of pericarp, i.e. the absence of a nut or seed or where the nut or seed occupies a volume less than 15% of the total fruit volume and/or where the destruction of the nut or seed during the process is irrelevant to the commercial effectiveness of the extraction process and/or the quality of the extracted end product thereby overcoming the problems and shortcomings of the prior art. Although there are systems and methods for the same in the prior art that have grown tremendously, for many practical purposes, there is still considerable room for improvement.

SUMMARY OF THE INVENTION

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.

It is an object of the present invention to provide an improved system and method for continuous extraction of liquid from the pericarp of fruit, more particularly in the absence of a kernel nut or seed or where the nut or seed occupies a volume less than 15% of the total fruit volume and/or where the destruction of the nut or seed during the process is irrelevant to the commercial effectiveness of the extraction process and/or the quality of the extracted end product.

Accordingly, the present invention provides a system for continuous extraction of liquid from the pericarp of fruit. The system of the present invention can be characterized by a first compression conveyor screw configured for processing the pericarp along a feeding and compression zone defined thereof, comprising a conical shaft having a proximal end, a distal end and a plurality of helical screw flights formed thereon, wherein each of the plurality of helical screw flights has a variable pitch and a variable flight depth that decreases in a proximal direction extending from the proximal end to the distal end of the conical shaft, wherein the first compression conveyor screw increasingly compresses, using the plurality of helical screw flights, the pericarp as progressing therealong; and a second compression conveyor screw configured for processing the pericarp conveyed from the first compression conveyor screw along a compression and metering zone defined thereof, comprising a disk-shaped member comprising a central hub and an annular rim having a plurality of apertures formed thereon; and a perforated pressure plate coupled to the disk-shaped member for releasing the liquid from the pericarp compressed thereof therethrough, wherein the second compression conveyor screw directs the pericarp towards the central hub through the plurality of apertures and thereby to the perforated pressure plate prior to a final compression. Preferably, the system further comprises a mandrel rotatably extending through the first compression conveyor screw via the conical shaft and the second compression conveyor screw via the disk-shaped member and the perforated pressure plate. Preferably, the mandrel and the central hub of the disk-shaped member form a gap therebetween to define an exit orifice, through which the pericarp is subject to the final compression and is discharged.

Preferably, the gap of the exit orifice thereof is adjustable by way of a mandrel nut that holds the mandrel.

Preferably, the system further comprises a perforated cylindrical cage that houses the first compression conveyor screw. Preferably, the perforated cylindrical cage comprises a tubular body having a side wall provided with perforations, through which the liquid from the pericarp compressed in the feeding and compression zone is expelled and collected. Preferably, the liquid collected thereof is decanted to, through a drain pipe, a liquid sump of which collects the liquid of the pericarp as released from the perforated pressure plate thereof.

Preferably, the system further comprises a drive assembly configured for causing rotational movement of the first compression conveyor screw and the second compression conveyor screw, comprising a slewing ring gear driven by a pinion gear; a drive plate mounted to the slewing ring gear; and a hydraulic motor coupled to the pinion gear. Preferably, the system further comprises a cylindrical lid attachable to a system casing, wherein the cylindrical lid comprises an entry port for receiving the pericarp of fruit and for directing the same to the first compression conveyor screw; and a cam ring disposed on and for holding the cylindrical lid thereof. Preferably, the plurality of helical screw flights is arranged radially on the conical shaft.

Preferably, the plurality of apertures of the disk-shaped member is an arc- shaped aperture.

In accordance with another aspect of the present invention, a method for continuous extraction of liquid from pericarp of fruit is provided.

The method of the present invention can be characterized by the steps of subjecting the pericarp to a feeding and compression zone, wherein the pericarp is increasingly compressed by a first compression conveyor screw as progressing along a plurality of helical screw flights having a variable path and a variable flight depth that decreases in a proximal direction extending from a proximal end to a distal end of a conical shaft; collecting the liquid of the pericarp compressed in the feeding and compression zone; subjecting the pericarp conveyed from the feeding and compression zone to a compression and metering zone, wherein the pericarp is directed by a second compression conveyor screw to a central hub of a disk- shaped member through a plurality of apertures formed thereon and thereby to a perforated pressure plate; collecting the liquid of the pericarp as released from the perforated pressure plate; subjecting the pericarp gathered at the central hub to an exit orifice for a final compression, wherein the exit orifice is a gap defined between a mandrel and the central hub, wherein the pericarp is discharged once the final compression is completed; and combining the liquid of the pericarp from the feeding and compression zone and the compression and metering zone.

If the processing losses due to continuous pressing are to be reduced, the kernel nuts must be removed from the digested mash, either before the digestion process or during the digestion process. By removing the kernel nuts, it is therefore an advantage of the present invention that reduces the flight depth and therefore the distance and time needed for the liquid to travel from the conical shaft's root radius to the outer shaft diameter. Moreover, with the kernel nuts removed, the size of the first and the second compression conveyor screws can be reduced by an amount previously occupied by the kernel nuts. The present invention, advantageously, results in a significantly smaller screw and press configuration to achieve an equivalent throughput capacity. Considerably, more pressure can be applied to the pericarp (in excess of 50kg/cm²) thereby causing more oil to be extracted without fear of kernel nuts breaking. However, if kernel nuts are removed from the digested mash, the configuration of the screw also has to change to avoid conflict between the throughput objectives and the machine configuration. When the volume of the digested mash is reduced by the volume previously occupied by the kernel nuts, the volume of material conveyed by the helix is reduced considerably. The reduction in volume can be achieved by reducing the depth of the screw. However, if the throughput is to remain the same, the screw outside diameter must be maintained. This means that the root radius of the screw is increased due to the reduction in screw depth. This represents an inefficient use of material resulting in a heavier screw and a lost opportunity to reconfigure the screw press. If the outside diameter of the screw is reduced proportionately with the root diameter, the throughput is significantly compromised because the mean diameter, i.e. the root diameter plus one flight depth will result in a reduced circumference and therefore screw flight volume.

The foregoing and other objects, features, aspects and advantages of the present invention will become better understood from a careful reading of a detailed description provided herein below with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendant advantages thereof will be readily as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

Figure 1 illustrates a prior art of a horizontal axially rotating helical screw;

Figure 2 illustrates the compression effect of the prior art axially helical screw shown in Figure 1 ;

Figure 3 illustrates the compression taking place at the metering zone of the prior art axially helical screw shown in Figure 1 ;

Figure 4 shows an isometric view of an assembly comprising the feeding and compression zone a first compression conveyor screw, a second compression conveyor screw and a drive assembly according to one embodiment of the present invention;

Figure 5 shows an exploded view of an assembly in Figure 4 according to one embodiment of the present invention;

Figure 6 shows an isometric view of a perforated cylindrical cage according to one embodiment of the present invention; Figure 7 shows an isometric view of a first compression conveyor screw according to one embodiment of the present invention;

Figure 8 shows an isometric view of a disk-shaped member belonging to a second compression conveyor screw according to one embodiment of the present invention;

Figure 8a shows an isometric view of a perforated pressure plate belonging to a second compression conveyor screw according to one embodiment of the present invention;

Figure 9 shows a cross sectional view of a system for continuous extraction of liquid from pericarp of fruit according to one embodiment of the present invention; Figure 10 shows a cross sectional view of a system casing suitable for the system in Figure 9 according to one embodiment of the present invention; and

Figures 1 1 a and 1 1 b show an isometric view of the extended central hub exit orifice comprised of the central round shaft, conical mandrel, perforated bleeder flutes extending radially towards perforated plate inserts at the periphery of the extended cylindrical hub compression zone.

It is noted that the drawings may not be to scale. The drawings are intended to depict only typical aspects of the invention, and therefore should not be considered as limiting the scope of the invention. In the drawings, like numberings represent like elements between the drawings.

DETAILED DESCRIPTION OF THE INVENTION The present invention describes a system and a method for continuous extraction of liquid from pericarp of fruit, more particularly, to extraction of liquid (i.e. water, juice and oil) from an agricultural mass but relies on the fruit, nut or bean consisting entirely of pericarp or where the nut or seed occupies a volume less than 15% of the fruit volume or where the destruction of the nut or seed during the process is irrelevant to the commercial effectiveness and/or end product quality of the extraction process or where the nut or seed has been removed from the fruit before pressing. Ideally, if the volume of the nut or seed is greater than 15% of the total fruit volume, the pericarp which consists of epicarp, mesocarp and endocarp should first be separated from the nut or seed before pressing to ensure sufficient pressure can be applied to extract the liquid. While the present invention has broad applications as discussed, it offers specific and significant potential for the extraction of crude palm oil from oil palm fruit mesocarp and this will be discussed in detail. Oil palm fruit mesocarp contains oil entrapped within alpha cellulosic carbohydrates which are surrounded by hemi-cellulosic carbohydrates, rigid lignin fibre and water. As a result of efficient sterilisation and subsequent digestion some oil is released as virgin oil during digestion process and much of the hemi cellulosic carbohydrates (polysaccharides) are broken down to more simple sugars, Pentose and Hexose by water and heat induced hydrolysis while the lignin, kernel nut and alpha cellulosic carbohydrate entrapping the remaining oil rely on a subsequent processing method (pressing or centrifuging) to extract oil.

According to one preferred embodiment of the present invention, the system comprises a first compression conveyor screw 100 and a second compression conveyor screw 200, an assembly view of which is shown by Figure 4. This assembly of compression conveyor screws 100 and 200 is further engaged to a perforated cylindrical cage 400 and to a drive assembly 600. The first compression conveyor screw 100 is preferably housed or encased by the perforated cylindrical cage 400. The second compression conveyor screw 200 will be attached to one end of the perforated cylindrical cage 400 to make this one end closed as opposed to its free or open end. The second compression conveyor screw 200 is attached to one end of the perforated cylindrical cage 400 the first compression screw 100 to facilitate the smooth continuous flow of pericarp from the feeding zone of the first screw 100 to the end of the metering zone of the second screw 200. The axial rotational movement of the first compression conveyor screw 100 and the radial movement of the second compression conveyor screw 200 is caused and driven by the drive assembly 600 which is coupled or plugged appropriately to this end. An exploded view of this assembly is shown in Figure 5. The perforated cylindrical cage 400, as shown in Figure 6, comprises a tubular body 401 that has a side wall 402 with perforations and/or vertical bars. Along the tubular body 401 , reinforcing ribs may be deployed to reinforce its structure. At one of its two free ends, a flange for engaging with the other parts of the system such as a system casing 701 may be provided.

A mandrel 300, preferably a tapered cylindrical mandrel, is deployed to the system of the present invention. The mandrel 300 is secured to a shaft 101 which extends through the first compression conveyor screw 100 and the second compression conveyor screw 200, the central hub 201 a, i.e the final ompression zone of the second compression conveyor screw 200, the perforated pressure plate part 202 and an extended compression zone. The mandrel 300 is preferably secured to the shaft 101 by a mandrel nut 302 and it may facilitate rotational movement as required by the system of the present invention.

The extended compression zone cylindrical wall is comprised of six plate inserts that when they are all inserted form a perforated cylinder. The shaft 101 that secures the conical mandrel 300 and facilitates raising or lowering of the conical mandrel 300 has been extended and slotted along its axis to accommodate six perforated bleeder flutes. The purpose of the extended compression zone is to remove residual oil from the exiting fibre. The perforated bleeder flutes shorten the path for the oil to travel by enabling the oil to bleed into the bleeder flutes from the side as well as radially to the perforated plate 202 inserts which form the wall of the extended compression zone.

The first compression conveyor screw 100 is configured for receiving and processing the pericarp by virtue of causing the same to progress along a feeding and on to a compression zone. It is worth noting that this particular zone is a combination of feeding and compression zones. The structure of the first compression conveyor screw 100 defines and constitutes the feeding and compression zone. The first compression conveyor screw 100 preferably comprises a conical or tapered shaft 101 which has a proximal end and a distal end. The conical shaft 101 has a central hollow portion that is adopted to receive the mandrel 300 therethrough. The conical shaft 101 has a continuously increasing diameter extending from the proximal end to the distal end. A plurality of helical screw flights 102 is formed and arranged radially on the conical shaft 101 . Each of the plurality of helical screw flights 102 has a variable pitch and a variable flight depth that decreases in a proximal direction extending from the proximal end to the distal end of the conical shaft 101 . As the diameter of the conical shaft 101 is continuously increasing, the pitch and the flight depth of the helical screw flight 102 decreases. In other words, as the pericarp travels axially along the helical path of the first compression conveyor screw 100 that is the pericarp transport direction, the "tunnel" as confined by the enclosing surfaces, i.e. the flight surface, the shaft surface, the neighboring flight surface and the side wall 402 of the perforated cylindrical cage 400 is becoming relatively smaller and narrower from a beginning to an end of the helical path of one helical screw flight 102 that advantageously provides a continuous and increasing compression onto the pericarp along the way. Therefore, the liquid from the pericarp compressed thereof is continuously collected along the entire progression on the helical path as the conical shaft 101 rotates. At the feeding and compression zone, the liquid is preferably expelled via perforations formed on the side wall 402 of the tubular body 401 of the perforated cylindrical cage 400 (see Figure 6). The collected liquid will be channeled to a liquid reservoir on an upper part of the system before it is decanted to a liquid sump 501 through a drain pipe 500. The first compression conveyor screw 100 preferably increasingly compresses the pericarp progressing therethrough by virtue of reduced depth of the helical screw flights 102.aila

In one embodiment, the present invention adapts two helical screw flights 102 which are alternately arranged along the radial surface of the conical shaft 101 as shown in Figure 7. Each helical screw flight begins and ends at different points of the proximal end and the distal end, respectively, of the conical shaft 101 . The helical path of each of the three helical screw flights 102 is of a bigger surface area at the beginning and becoming narrower towards its end for compressing the pericarp travelling therethrough.

The second compression conveyor screw 200 is configured for processing the pericarp that is conveyed from the first compression conveyor screw 100, i.e. after an initial compression by the plurality of helical screw flights 102 thereof. The pericarp will be subject to a compression and metering zone. It is worth noting that this particular zone is a combination of compression and metering zones. The structure of the second compression conveyor screw 200 defines and constitutes the compression and metering zone. The second compression conveyor screw 200 preferably comprises a disc-shaped member 201 and a perforated pressure plate 202 as shown by Figure 8 and 8a, respectively. The perforated pressure plate 202 is positioned beneath, within the disk-shaped member 201 . The mandrel 300 which extends from the first compression conveyor screw 100 is further extended through the second compression conveyor screw 200 via the disk- shaped member 201 and the perforated pressure plate 202.

The disc-shaped member 201 has a main body with a central hub or cavity 201a (acts as the beginning of the extended of the extended central hub compression chamber) and extends through an annular rim 201 b surrounding the central hub 201a. The main body of the disc-shaped member 201 has a thickness forming a peripheral wall that may enclose the perforated pressure plate 202. A plurality of ribs may be disposed on the main body for the purpose of engagement with the first compression conveyor screw 100 or the drive assembly 600. On the main body, particularly on the area of the annular rim 201 b, there is provided a plurality of apertures 201 c formed thereon. The apertures 201 c are preferably an arc-shaped aperture as shown in Figure 8. Each of the apertures 201 c has a radius that is smaller than that of the main body, and that is larger than that of the central hub 201 a. It extends along the perimeter of the disk-shaped member 201 forming a curved figure or arc. The aperture 201 c is extended through the main body of the second compression conveyor screw 200 across the thickness thereof, giving access to the other side of the disk-shaped member 201 and to the perforated pressure plate 202. The aperture 201 c protrudes downwardly and helically through a tapering portion of the main body of the second compression conveyor screw 200 forming an angled trench. The first compression conveyor screw 100 and the second compression conveyor screw 200 are joined by a plurality of keys and screws. The combined screw 100 200 are engaged by a drive assembly 600 for transmitting the torque induced by the hydraulic motor 604 via the spur gear reduction. By combining both screw 100 200, a continuous and seamless spiral is formed comprising a conical shaft beginning at a proximal end, and ending distal at the final compression zone. The helical profile scribed by combining the screws 100 200 causes a plurality of arc shaped apertures 201 c the number of which is determined by the plurality of screw flights imposed on the disc-shaped of the second compression conveyor screw 200 through which the pericarp transitions from a vertical induced helical axial flow to a horizontal induced radial helical flow as the combined rotation of both vertical and horizontal helical profiles rotation compels the pericarp towards the central disc hub 201 a compression zone.

The perforated pressure plate 202 which is fixed distally separated from the disc-shaped member 201 comprises perforations. The perforations allow the liquid from the pericarp to pass through multiple perforations due to the pressure induced by the central disc opposing the forces induced by the rotation of the respective helixes of the combined screws 100 200 and the tapering portion of the angled trench of the second compression conveyor screw 200. The intermediate compression, which is executed after the initial compression by the first compression conveyor screw 100, is achieved by virtue of subjecting the pericarp to move towards the central hub 201a through the apertures 201 c as the discshaped member 201 rotates, and thereby to arrive on the perforated pressure plate 202. The liquid from the pericarp as compressed in the compression and metering zone of the second compression conveyor screw 200 is forced through the perforated pressure plate 202 and is collected in the liquid sump 501 which also collects the liquid of the pericarp from the feeding and compression zone, i.e. from the first compression conveyor screw 100 (see Figure 9). While the liquid is being collected, the compressed pericarp progresses towards and accumulates at the central cylindrical hub 201a where the mandrel 300 is extending through. Between the mandrel 300 and the underside near the compression zone of the central cylindrical hub 201 a, there is a gap created by adjusting the nut 302.

This circular gap with a width defines an exit orifice 301 through which the pericarp from the compression and metering zone (i.e. after the intermediate compression) is subject to a final compression and thus is discharged. This circular gap creates the pressure by defining the restricted exit orifice 301 through which the pericarp exiting from the extended central hub 201a at the compression zone is discharged. The pressure created from the mandrel 300 at the exit orifice due to the restricted flow of pericarp through the exit orifice 301 exerts a force on the walls of the helix spirals and the walls of the central hub 201 a of the second compression conveyor screw 200. The gap of the exit orifice 301 may be adjustable by way of the mandrel nut 302 that holds the mandrel 300. Additional pressure is created by reducing the diameter of the exit orifice beneath the perforated plate at compression zone 201 a. By adjusting the mandrel nut 302, the area through which the pericarp can escape varies, thereby creating the back pressure against the apertures or flights 201 c of the first compression conveyor screw 100, the second compression conveyor screw 200, the bleeder flutes, the cylindrical wall pressure inserts of the central hub 201 a that is necessary to compress the pericarp to expel the liquid, i.e. water and oil. When the gap is small, the pressure is maximised because the volume of fibre discharged is reduced relative to that being continuously conveyed by the combined screw parts towards the central hub 201a compression zone chamber. By adjusting the pressure in the compression chamber, it is possible to determine the amount of oil and water which can be removed from the exiting pericarp/mesocarp fibre.

In accordance with another preferred embodiment, the perforated pressure plate 202 may comprise of vertical square bars equally spaced about its circumference so as to provide a space between each square bar for the liquid to be expelled and collected from the feeding and compression zone of the first compression conveyor screw 100.

Since the helix of the second compression conveyor screw 200 is at 90 degree to the axis of rotation, the length of the screw's compression face is significantly compacted, e.g. shorter and therefore the pressure area of the screw is reduced, without compromising the pressure exerted on the pericarp, i.e. the mesocarp fibre, due to the mechanical advantage induced by the second screw helix angle. Since the length of the screw's compression face is reduced so is the friction force effect acting on the same.

As the screw is at 90 degree to the axis of rotation, the pericarp is conveyed towards the pressure zone at the center of the second compression conveyor screw 200, i.e. the central hub 201 a instead of towards the end of the screw which is typical of a screw helix rotating and progressing material axially in a horizontal direction as opposed to forces created by the rotating disc-shaped screw part 200 which progresses the pericarp radially in a horizontal direction towards the compression zone. The shorter distance to the pressure zone ensures the pressure effect on the pericarp is not lost over successive screw flights along the screw axis which have the helix set axially to progress the material in a horizontal direction towards the pressure zone at the end of the horizontal parallel screws as charaterised by the prior art.

The drive assembly 600 may be configured to cause the axial rotational movement of the first compression conveyor screw 100 and the radial rotation of the second compression conveyor screw 200. The drive assembly 600 comprises a slewing ring gear 601 and a drive plate 603 as shown by Figure 5. The slewing ring gear 601 mounted to the drive plate 603 is preferably driven by a pinion gear 602 (see Figure 9). A hydraulic motor 304 may be employed at the drive assembly 600 for driving the pinion gear 602. As the first compression conveyor screw 100 and the second compression conveyor screw 200 are driven by the relatively large slewing ring gear 601 , the drive torque is increased by the ratio between the slewing ring gear 601 and the pinion gear 602. This reduces the size of the hydraulic motor or gearbox 604 needed to facilitate the torque. The system of the present invention further comprises a cylindrical lid 700 and a cam ring 703, see Figure 9 and 10. The cylindrical lid 700 is attachable to the system casing 701. The cylindrical lid 700 comprises an entry port 702 for receiving the pericarp of fruit and for directing or guiding the same to the feeding and compression zone of the first compression conveyor screw 100. The cam ring 703 is disposed on the cylindrical lid 700 thereof and it is primarily adapted for securely holding the cylindrical lid 700 to the system casing 701. When the cam ring 703 is rotated to an open position, the cylindrical lid 700 can be removed. Conversely, when the cam ring 703 is rotated to a close position, it exerts pressure on the cylindrical lid 700 to secure the same against the perforated cylindrical cage 400. The quick acting cam ring 703, advantageously, has allowed for removal of the lid 700 and enabling wear components to be quickly assessed for inspection and servicing.

Figure 9 provides the cross sectional view of the assembled system along with an indication of the feeding and compression zone of the first compression conveyor screw 100, and the compression and metering zone of the second compression conveyor screw 200. As it can be seen, the mandrel 300 is extending through the first compression conveyor screw 100, the second compression conveyor screw 200, the central screw hub of the second screw part, the extended central hub compression zone and the cylindrical opening at the underside of the extended central hub compression zone to create a discharge orifice 301 the size of which can be adjusted by the mandrel shaft 300 .

The drive assembly 600 is properly deployed into the system to correspondingly cause the combined rotational movement of the first compression conveyor screw 100 and the second compression conveyor screw 200. During its operation, the pericarp is introduced into the system via the entry port 702. The pericarp is guided towards the feeding zone of the first compression conveyor screw 100, particularly to the plurality of helical screw flights 102 and is subject to an initial feeding and compression induced by the first compression conveyor screw 100. The liquid from the pericarp is expelled through the perforated cylindrical cage 400 housing the first compression conveyor screw 100 and is collected in the liquid reservoir before being decanted to the liquid sump 501. After the initial compression, the pericarp seamlessly exits the first compression conveyor screw 100 and enters the second compression conveyor screw 200, particularly the disc-shaped member 201 of the second compression conveyor screw 200. At the transition point from the first screw 100 to the second screw 200, the advancement of the pericarp transitions from a vertical axial movement to a horizontal radial movement as it is conveyed seamlessly towards the central hub 201a through the plurality of arc-shaped apertures 201 c and thereby to the perforated pressure plate 202 towards the central cylindrical hub compression zone. As the pericarp is conveyed radially and compressed vertically along a plurality of helix flights towards the centralhub 201 a compression zone liquid contained within the pericarp is forced through the perforations of the perforated pressure plate 202 and is collected in the liquid sump 501 along with the liquid collected from the initial compression of the first screw 100. At the end of the second screw 100, i.e. the central cylindrical shaped compression zone the volume of the pericarp minus the liquid forced through the perforated plate 202 is forced to occupy the controlled volume of the central cylindrical hub 201 a and extended central pressure zone hub due to the gap set between the mandrel 300 and the exit orifice 301 thereby creating sufficient back-pressure along the plurality of screw flights of the second screw 200 to impose a force on the perforated plate 202 beneath the second screw 200 to expel liquid through the perforated openings of the pressure plate 202 and the perforated openings of the bleeder flutes to further expel liquid contained within the pericarp through the extended central hub compression zone. The liquid collected in the liquid sump 501 may be decanted to another container via the liquid discharge connected thereto.

Figure 10 illustrates the system casing 701 which is suitable for use in the present invention. The system casing 701 preferably encloses or houses most of the components that belongs to the system. The casing 701 may comprise of a number of parts attachable to each other by bolts and nuts, welds and the like. The system casing 701 preferably has an elevated tubular leg or stand to support the assembled system.

The terms "a" and "an," as used herein, are defined as one or more than one. The term "plurality," as used herein, is defined as two or more than two. The term "another," as used herein, is defined as at least a second or more. The terms "including" and/or "having," as used herein, are defined as comprising (i.e., open language).

While this invention has been particularly shown and described with reference to the exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention as defined by the appended claims.

Claims

A system for continuous extraction of liquid from pericarp of fruit, characterized in that, the system comprising:

a first compression conveyor screw (100) configured for processing the pericarp along a feeding and compression zone defined thereof, comprising: a conical shaft (101 ) having a proximal end, a distal end and a plurality of helical screw flights (102) formed thereon, wherein each of the plurality of helical screw flights (102) has a variable pitch and a variable flight depth that decreases in a proximal direction extending from the proximal end to the distal end of the conical shaft (100),

wherein the first compression conveyor screw (100) increasingly compresses, using the plurality of helical screw flights (102), the pericarp as progressing therealong; and

a second compression conveyor screw (200) configured for processing the pericarp conveyed from the first compression conveyor screw (100) along a compression and metering zone defined thereof, comprising:

a disk-shaped member (201 ) comprising a central hub (201 a) and an annular rim (201 b) having a plurality of apertures (201 c) formed thereon; and

a perforated pressure plate (202) coupled to the disk-shaped member (201 ) for releasing the liquid from the pericarp compressed thereof therethrough,

wherein the second compression conveyor screw (200) directs the pericarp towards the central hub (201 a) through the plurality of apertures (201 c) and thereby to the perforated pressure plate (202) prior to a final compression.

The system according to Claim 1 further comprises a mandrel (300) rotatably extending through the first compression conveyor screw (100) via the conical shaft (101 ) and the second compression conveyor screw (200) via the disk- shaped member (201 ) and the perforated pressure plate (202).

The system according to Claim 2, wherein the mandrel (300) nd the central hub (201 a) of the disk-shaped member (201 ) form a gap therebetween to define an exit orifice (301 ), through which the pericarp is subject to the final compression and is discharged.

4. The system according to Claim 3, wherein the gap of the exit orifice (301 ) thereof is adjustable by way of a mandrel nut (302) that holds the mandrel

(300).

5. The system according to Claim 1 further comprises a perforated cylindrical cage (400) that houses the first compression conveyor screw (100).

6. The system according to Claim 5, wherein the perforated cylindrical cage (400) comprises a tubular body (401 ) having a side wall (402) provided with perforations, through which the liquid from the pericarp compressed in the feeding and compression zone is expelled and collected.

7. The system according to Claim 6, wherein the liquid collected thereof is decanted to, through a drain pipe (500), a liquid sump (501 ) of which collects the liquid of the pericarp as released from the perforated pressure plate (202) thereof.

8. The system according to Claim 1 further comprises a drive assembly (600) configured for causing rotational movement of the first compression conveyor screw (100) and the second compression conveyor screw (200), comprising: a slewing ring gear (601 ) driven by a pinion gear (602);

a drive plate (603) mounted to the slewing ring gear (601 ); and

a hydraulic motor (604) coupled to the pinion gear (602).

9. The system according to Claim 1 further comprises:

a cylindrical lid (700) attachable to a system casing (701 ), wherein the cylindrical lid (700) comprises an entry port (702) for receiving the pericarp of fruit and for directing the same to the first compression conveyor screw (100); and

a cam ring (703) disposed on and for holding the cylindrical lid (700) thereof.

10. The system according to Claim 1 , wherein the plurality of helical screw flights (1 02) is arranged radially on the conical shaft (1 01 ).

1 1 . The system according to Claim 1 , wherein the plurality of apertures (201 c) of the disk-shaped member (201 ) is an arc-shaped aperture.

12. A method for continuous extraction of liquid from pericarp of fruit, characterized in that, the method comprising the steps of:

subjecting the pericarp to a feeding and compression zone, wherein the pericarp is increasingly compressed by a first compression conveyor screw (1 00) as progressing along a plurality of helical screw flights (102) having a variable path and a variable flight depth that decreases in a proximal direction extending from a proximal end to a distal end of a conical shaft (101 );

collecting the liquid of the pericarp compressed in the feeding and compression zone;

subjecting the pericarp conveyed from the feeding and compression zone to a compression and metering zone, wherein the pericarp is directed by a second compression conveyor screw (200) to a central hub (201 a) of a disk- shaped member (201 ) through a plurality of apertures (201 c) formed thereon and thereby to a perforated pressure plate (202);

collecting the liquid of the pericarp as released from the perforated pressure plate (202);

subjecting the pericarp gathered at the central hub (201 a) to an exit orifice (301 ) for a final compression, wherein the exit orifice (301 ) is a gap defined between a mandrel (300) and the central hub (201 a), wherein the pericarp is discharged once the final compression is completed; and

combining the liquid of the pericarp from the feeding and compression zone and the compression and metering zone.