FIELD OF INVENTION

The invention generally relates to a system and method for extraction of liquid from drupe fruits. Particularly, the system and method disclosed in the present invention is to extract palm oil from oil palm fruitlets in an effective and cost and energy-saving manner.

BACKGROUND OF THE INVENTION

Palm oil has been very popular lately in view of its advantages over the other vegetable oil. When palm oil is compared to vegetable oils obtained from crops such as sunflower, soybean or rapeseed, palm oil is the highest-yielding oil crop, as it only needs half the land required by the other crops to produce the same amount of oil. Apart from its high yield, it is also known to be widely used in the preparation of food and cosmetic products due to its health benefits. The well- known advantages have attracted tremendous demand for palm oil over the years, which has in turn increased the research and developments on the plantation of oil palm trees and the production of palm oil. However, despite incremental technical changes to the milling process, processing equipment has remained relatively unchanged.

Antecedent to the extraction process, fresh fruit bunches, FFB, are subjected to a sterilization process which causes the fruitlets to separate from the fruit rachis or stalk. This is a consequence of temperature and/or pressure water induced hydrolysis and a moderate mechanical threshing operation. What remains after the mechanical threshing is defined as empty fruit bunch, EFB, and is generally used as a source of fertiliser or boiler fuel once residual oil is removed from the mechanical shredding and pressing. Crude palm oil, CPO, is obtained from the mesocarp and palm kernel oil, PKO, is obtained from the kernel nut of the fruitlet.

The fruitlets removed from the rachis after sterilization and mechanical threshing are comprised of mesocarps and kernel nuts. The mesocarp contains oil entrapped within alpha cellulosic carbohydrates surrounded by hemi-cellulosic carbohydrates, rigid lignin fibre and water. During sterilization, hemi-cellulosic carbohydrates are broken down to simple sugars such as pentose and hexose from the water and heat-induced hydrolysis. Subsequent extraction of oil and isolation of kernel nuts rely on a combination of digestion and pressing to recover the oil and kernel nuts. However, current digesters and press combinations have several limitations and caused significant palm kernel, PK, and crude palm oil, CPO, losses. These limitations are both idiosyncratic to digestion and pressing or in combination but require analysis as parts to fully comprehend the limitations of the prior art.

Generally, the digestion process is the beginning of the oil extraction process and occurs prior to the pressing process. The digestion process traditionally relies on a number of rotating blades, usually 8 units, in which they are set equally along a central rotating drive shaft to macerate the fruitlet to liberate oil, separate the palm kernel nut from the pericarp fibre and allow sufficient time for oil to leach out of the ruptured cells and for water to enter the void space left behind by the escaping oil. However, the fruitlets arriving at the digester are mostly desiccated due to long sterilisation cycles which cause water to evaporate from the cells surrounding the oil cells. This changes the pressure dynamic between the inside of the unbroken oil cells and the surrounding cells causing water to flow from the vacuole of oil cells due to an effect known as plasmolysis, as shown in figure 1.

The effect of plasmolysis significantly increases the burden of the digesters and challenges the capabilities of the present digesters in a number of significant ways. Firstly, existing digester would commonly include slowly rotating impeller blades that are extremely inefficient at providing sufficient friction to induce cell rupture within the residence time created by the inconsistent arrival of fruitlet and/or the volumetric capacity of the prior arts. Secondly, when maceration is occurring, the mixture of oil, fibre, kernel nuts and water created is not sufficiently hypotonic for water to rehydrate the cells due to osmosis or for water to occupy the void left by escaping oil from ruptured cells. This is illustrated in figure 2. When water is absorbed into unbroken cells it increases the turgid pressure within the cell to enhance the effectiveness of the subsequent pressing operation. Similarly, water occupying the void spaces left behind by escaping oil helps to purge ruptured cell of residual oil during the pressing operation. Thirdly, the volume of the prior arts does not allow sufficient residence time for oil to escape from ruptured cells and separate due to buoyancy and the force of gravity. However, regardless of the limitations of the prior arts, by the end of the digestion process, the fruitlets are converted to a digested mash of sorts, a mixture of kernel nuts, cellulosic fibre material, water, crude oil and debris mainly silica sand. Due to the limitations described, the digestion process only partially achieves the intended objective. At the end of the process, the digested mash is expelled to the screw press, as illustrated in figure 3, which is a conventional apparatus for the extraction of oil from palm fruits. Those familiar with the oil palm industry know that the Tenera species is the most commonly used species for commercial cultivation. Tenera is a hybrid cross between Dura and Pisifera palms. As compared to its parents, Tenera is different because of its high mesocarp to kernel shell nut ratio. The continuous pressing to extract oil from Tenera fruit results in trade-off between either maximising CPO or PK. This is due to the volume of mesocarp fibre to kernel ratio, as shown in figure 4. In fact, when too much pressure is applied to the digested mash, a high PK loss is inevitable, whereas too little pressure applied to the digested mash results in a high CPO loss. In the pressing operation, CPO is pressed from the mesocarp thereby reducing the volume of the mesocarp till it equals that of the volume of the kernel nuts. This is defined as the equilibrium point and regardless of attempts to remove more CPO by increasing the pressure, a significant volume of oil remains in or on the mesocarp. Adding more pressure to remove this oil fraction from the mesocarp simply sacrifices more kernel nuts without removing additional oil which remains attached to fibre and residing within the void spaces of the remaining nuts.

Beyond the equilibrium point where nut breakage intersects oil recovery, as shown in figure 5, the rate of nut breakage slows significantly regardless of incremental pressure increases as does the rate of oil recovery. Beyond 8MPa, the rate of CPO recovery decreases significantly resulting in as much as 1.0% on FFB weight remaining in or on the fibre and as much as 0.5% of kernel on FFB weight being lost. Research previously conducted at a mill in Sabah confirmed that on average 1.5% of FFB tonnes remained on or in mesocarp fibre after pressing. Further, on average of 0.5% of FFB tonnes as PK was lost as a result of nut breakage during pressing.

Apart from the above limitation, the inefficiency of the conventional digester and screw press combination is further limited by the inability of the system to accommodate variations to the arrival rate of fruitlets to the extraction system due to output inconsistencies from the threshing station. While some prior arts weigh the mass of fruitlets loaded into the digester and opens and closes chute doors automatically to allow or prevent more or less fruitlets being fed into the digester, the control logic fails to slow or stop the feed of fruitlet to the screw press or slow or stop the screw press. Moreover, the downstream cake breaker conveyor and depericarper continues to function when no fruitlets are available resulting in further power being consumed unnecessarily. Since the efficiency of the conventional system is highly dependent on the residence time of the fruitlets in the digester, there is no logic in the conventional system to determine that the fruitlet has resided in the digestion chamber for sufficient duration thereby limiting the conventional digester for its intended purpose Furthermore the sequence of process events which follow, including the screw press are not processor-controlled to slow, switch on/off based on the digested mash entering the screw press from the digester. Moreover, as kernel nuts and fibre expressed from the screw press are fed to the depericarper cyclone, additional kernel nuts are lost as there is no processor-logic to vary cyclone speeds to induce adequate separation of fibre and kernel nuts.

US patent 5,039,455 A discloses a process of producing palm oil, in particular a continuous milling process for extracting palm oil. More specifically, the said patent discloses a process for continuous sterilization, stripping, and pressurized digestion of fruit bunches during the palm oil extraction stages. One of the embodiments of the patent discloses that the process includes continuously conveying fruitlets to a surge bin before being received by a steam pressurized digester. In the surge bin, the fruitlets are kept under a particular retention period so as to control and regulate the flow of fruitlets to the digester. The patent document only emphasizes on the need for the fruitlets to be kept in retention for a specific amount of time. No part of the patent document discloses the size or volume of the retention area, which may not be sufficient in providing residence time for oil to escape from ruptured cells and separate due to buoyancy and the force of gravity.

US patent 9,862,911 B2 discloses a system and process for palm oil extraction integrally configured for processing entire fresh fruits including rachis, spikes and seeds or fruits by stages of cracking, threshing, dynamic sterilization and subsequent pressing. The patent aims to increase the percentage of oil extraction with less equipment and a smaller workspace compared to conventional systems and apparatuses. The patent also explained that the system and process require small amount of water and energy for the extraction. Whilst the system and process of the patent comprise a metering mechanism allowing dosed and controlled passage of the fruitlet through the hopper to the cracking apparatus, no part of the patent discloses the need to be more accurate in terms of the period of time the fruitlets are resident in particular parts of the system. In that case, it would not be possible to determine if there is sufficient time for oil to effectively be removed from the fruitlets before advancing to another stage of the process. In view of the above, there is therefore a need for the present invention to provide a system and method for effectively extracting palm oil from its fruitlets that addresses the disadvantages of the prior arts.

SUMMARY

The present invention discloses a system for extracting oil from drupe fruits, in which the system comprises a weigh hopper with an intermediate feeder chute for controlling feed of fruitlets to determine throughput variations and to facilitate mass balance calculations of the fruitlets, a first separation chamber for separating and compressing kernel nut and mesocarp fibres of the fruitlets liberating oil in the process, a second separation chamber for compressing, lacerating and macerating the fruitlets to extract oil, a third separation chamber for extricating mesocarp fibres of the fruitlets, washing and discharging kernel nuts, a first pressing chamber for compressing mesocarp fibres of the fruitlets to further recover oil, a hydration chamber for soaking and agitating the fibres in a boiling hypotonic solution to liberate oil and thereafter to remove fibres mechanically, a recycling and recovery tank for receiving and recycling the hypotonic solution from and to the hydration chamber and for further recovering oil leached into the hypotonic solution during hydration, a second pressing chamber for further compressing the fibres obtained from the hydration chamber to recover oil, and a fourth separation chamber for further separating oil and non-oily solids, NOS, from all extraction points and oil streams, a bucket elevator for receiving fibre discharged from the first pressing chamber as well as the fourth separation chamber for collecting discharged and suspended non-oily solids, NOS, fibres suspended in the oil from the various oil streams, wherein the system is capable of accommodating variations in the arrival of the fruitlets from a threshing station thereafter regulating the flow of fruitlets and controlling the durations and operations of the downstream processes of the system (1) in order to increase efficiency of the oil extraction from the fruitlets.

Also disclosed is a method for extracting oil from drupe fruits, the method is characterized by the steps of feeding fruitlets into a weigh hopper and intermediate feeder chute, to determine throughput variations and facilitate mass balance calculations of the fruitlets, wherein the weigh hopper is capable of regulating the flow of fruitlets and controlling the durations and operations of the downstream processes of the method in order to increase efficiency of the oil extraction from the fruitlets thereafter discharging the fruitlets into a first separation chamber, in which the first separation chamber separates and compresses kernel nut and mesocarp fibres of the fruitlets to partially remove oil, conveying the fruitlets into a second separation chamber, in which the second separation chamber further compresses, lacerates and macerates the fruitlets to further remove oil from the fruitlets, discharging the fruitlets into a third separation chamber, in which the third separation chamber extricates mesocarp fibres from the surroundings of the palm kernel nuts, feeding the mesocarp fibres into a first pressing chamber, in which the first pressing chamber compresses the mesocarp fibres, thereafter conveying the mesocarp fibres to a hydration chamber via the bucket elevator, in which the hydration chamber soaks the mesocarp fibres in a boiling hypotonic solution to further remove oil from the fibres due to the effect of gravity and mechanical agitation, after which the mesocarp fibres are directed to a second pressing chamber in which the second pressing chamber further compresses the mesocarp fibres to recover oil before the mesocarp fibre is finally discharged from the system as boiler fuel, while the hypotonic solution discharged from the hydration chamber is collected at the recycling and recovery tank and recycled back to the hydration chamber while oil clarified in the recycling and recovery tank is decanted. All oil streams from the various extraction points are directed to final separation chamber where non-oily solids, NOS, are separated from the collective oil streams. The oil is measured and discharged from the system for further treatment while the NOS are discharged to the bucket elevator along with the mesocarp fibres discharged from the first pressing station where both the NOS and the pressed mesocarp from the first pressing are lifted and discharged into the hydration chamber.

It is an object of the present invention to provide a system and method that utilize a combination of weigh hoppers to control the feed of fruitlets to determine throughput variations and to facilitate mass balance calculations of the fruitlets, thereby increasing the efficiency of the system since the amount of fruitlets as well as the duration of the processes in the system are controlled based on the throughput variations.

It is another object of the present invention to provide a system and method that process the fruitlets, including the processes of separating the kernel nut and mesocarp of the fruitlets and partially removing oil in the first separation chamber, compressing and lacerating the fruitlets to further remove oil in the second separation chamber, extricating the mesocarp and the palm kernel nuts of the fruitlets in the third separation chamber and compressing the mesocarp of the fruitlets in the first pressing chamber to further remove oil, before being soaked in the hydration chamber to further liberate oil, thereby allowing sufficient time and incremental mechanical force across all separation chambers and the hydration chamber to maximise the liberation of oil.

It is still an object of the present invention to provide a system and method that continue to process the fruitlets after the soaking of the fruitlets in the hydration chamber, particularly the second pressing chamber further compresses fibres collected from the hydration chamber and the recycling and recovering chamber, and the fourth separation chamber further separating oil and non-oily solids from the extraction, thereby maximising the effectiveness of the system.

It is further an object of the present invention to provide a system and method utilizing a weigh hopper to control the feed of fruitlets to determine throughput variations and to facilitate mass balance calculations of the fruitlets, thereby regulating the flow and amount of fruitlets in each stage and controlling the durations and operations of the downstream processes of the system, eventually saving the use of unnecessary power consumption.

BRIEF DESCRIPTION OF DRAWINGS

The invention will now be described with reference to the drawings wherein:

Figure 1 illustrates an example of sterilization induced plasmolysis.

Figure 2 illustrates an example of water rehydrating the cells due to osmosis upon the escape of oil from ruptured cells.

Figure 3 illustrates a conventional system for extracting oil from drupe fruit that comprises a digester and a twin screw press.

Figure 4 is a pie chart illustrating the Tenera fruit compositions in terms of percentages of fibre, water, oil and nut by volume of the fruit.

Figure 5 is a chart illustrating the amount of pressure applied to the fruits versus the percentages of broken nuts and oil loss.

Figure 6 illustrates a system for extracting oil from drupe fruits according to the present invention. Figure 7 illustrates a system for extracting oil from drupe fruits, where it is specifically constructed in a container structure assembly according to an embodiment of the present invention.

DETAILED DESCRIPTION

The following description is presented to enable a person of ordinary skill in the art to make and use the various embodiments. Descriptions of specific devices, techniques, and applications are provided only as samples. Various modifications to the examples described herein will be readily apparent to those of ordinary skill in the art, and the general principals defined herein may be applied to other examples and applications without departing from the scope of the various embodiments. Thus, the various embodiments are not intended to be limited to the examples described herein and shown, but are to be accorded the scope consistent with the claims.

The present invention discloses a system (1) and method for extracting oil from drupe fruits that results in cost and energy savings due to its operational efficiency. In particular, those features disclosed in the present invention which comprise a weigh hopper (11), an intermediate feeder chute (12), a first, second, third and fourth separation chambers (13, 14, 15, 20), a first and second pressing chambers (16, 18), a hydration chamber (17), a recycling and recovery tank (19), and a bucket elevator (21). The features are all electronically linked to monitor and control the parameters of the system (1). At the beginning of the extraction process, the drupe fruits are to be fed into a weigh hopper (11). According to one embodiment of the present invention, the weigh hopper (11) is preferably a "loss in weight" weigh hopper (11) that records a maximum and minimum weights of the fruitlets in the hopper at a given time. The difference between the maximum pre-set weight and the minimum pre-set weights determines the mass balance calculations of the fruitlets. Thereafter, the fruitlets are discharged into an intermediate feeder chute (12) that is coupled to the weigh hopper (11). When the pre-set minimum weight is registered by load cells supporting the weigh hopper (11), a hydraulically actuated chute door is opened to allow the passage of fruitlets into the hopper (11). The hydraulically actuated chute door closes once a maximum pre-set weight value is recorded in the hopper (11). In one embodiment of the present invention, it is explained herein that the fruitlets remain in the hopper

(11) till a signal is received from the adjoining weigh hopper (11) and intermediate feeder chute

(12) which is suspended from a set of autonomous load cells. When the minimum weight signal is received from the autonomous load cells that suspends the intermediate feeder chute (12) and weigh hopper (11), a butterfly valve in the hopper (11) is opened by a hydraulic actuator to discharge the fruitlets stored in the hopper (11) into the intermediate feeder chute (12). Once the fruitlets from the hopper (11) are discharged to the intermediate feeder chute (12), the butterfly valve is closed and the chute door opens to allow the discharge of fruitlets. In another embodiment of the present invention, as the measured amount of fruitlets received into the intermediate feeder chute (12) progressively reduces to a minimum pre-set value, fruitlets are once again discharged from the hopper (11) into the intermediate feeder chute (12). Such combined handshaking between the load cell supporting hopper (11) and the load cell supporting intermediate feeder chute (12) regulates the flow of fruitlets so that the system (1) ensures a measured amount of fruitlets based on the volumetric capacity of the system (1) while ensuring the system runs optimally by slowing or shutting down completely the maceration and extrication of fruitlets in the downstream processes when the flow of fruitlets from the threshing station is intermittent or stopped.

This is achieved when the butterfly valve remains closed for a pre-determined time frame due to not receiving a low-level weight signal from the load cells of the intermediate feeder chute (12). In the absence of a low-level weight signal to open the butterfly valve, the first and second and third separation chambers (13, 14, 15) are signalled to slow down the rate of maceration and extrication of the fruitlets and the mesocarp fibres, as well as the pressing in the first pressing chamber (16). Preferably, the rates of maceration, extrication and the first pressing are slowed down to half of its original rate. When fruitlets fail to arrive within a pre-determined time frame, the remaining chambers responsible for feeding and pressing will stop. Conversely, when the load cells of the hopper (11) records a low-level weight signal, it signifies the resumption of successive high or low-level signals in the hopper (11) within pre-programmed time references and a resumption of normal operation beginning with a reversal of the shut-down procedure.

Upon receiving the fruitlets from the intermediate feeder chute (12), the first separation chamber (13) and the second separation chamber (14) compress, lacerate and macerate the fruitlets to extract oil. In an embodiment of the present invention, the first separation chamber (13) further comprises an upper screw and barrel and a tapered screw where the fruitlets are compressed, lacerated and forcedly macerated to extract oil and to strip mesocarp fibres from kernel nuts of the fruitlets respectively, after which the compressed mash comprising fibre, oil and palm kernel nuts are forced through a lower tapered screw basket assembly having a series of fixed tapered reducing baskets lined with moveable blades that are capable of lacerating and stripping fibre from the kernel nuts. As the mashed fruitlets progress through the tapered screw basket assembly, fibres become snagged on protruding blade teeth and are pushed through blade walls by kernel nuts under pressure induced by rotating multi-start tapered screw. This action expels fibre, oil and water from inner chamber of the reducing baskets to outer cavity between the basket wall and the body of the second separation chamber (14). High-pressured aqueous solution pumped from the recycling and recovery tank (19) is intermittently sprayed to remove oil, water and fibre from the outer basket wall which is separated at the bottom of the second separation chamber (14). Specifically, the oil and water mixture is decanted through one outlet and the fibre is expelled through another outlet.

During maceration, blade teeth pierce alpha-celluloses to liberate oil as well as strip mesocarp fibre from kernel nuts. As the volume of successive basket stages reduce the volume of fibre retained moving forward, fibre, oil and water and progressively discharged from the system (1). Only the kernel nuts are trapped and remain confined within the basket to be finally discharged at the bottom of the reducing basket into the third separation chamber (15). In the third separation chamber (15), a controlled volume of high-pressured aqueous solution pumped from the recycling and recovery tank (19) is pressure-injected to remove oil from the kernel nuts and to force fibres through a number of fixed grate blades that are equivalently spaced, allowing passage of oil, fibres and water but retaining kernel nuts of the fruitlets. Moveable vertical grate blades positioned between the fixed grate blades are constructed in a manner to allow a mechanical actuated up and down movements to extricate mesocarp fibres that are loosely surrounding the kernel nuts. The mechanical actuation of the grate blades mentioned herein is powered by a variable speed motor that drives a spur gear drive linked to a cam rotor coupled to the grate blades. As lose fibres surrounding the kernel nuts are extricated through the fixed grate blades, the kernel nuts are progressively pushed and passed through the spaces between fixed grate blades towards an evacuation chute. At the point where the kernel nuts pass through the fixed grate plates, high-pressured aqueous solution pumped from the recycling and recovery tank (19) is sprayed towards the plates to remove remaining oil and fibres attached to the kernel nuts. Oil and water are then decanted while the remaining mesocarp fibres are simultaneously fed to the first pressing chamber (16).

The first pressing chamber (16) is responsible to press up to 95% of oil and water remaining in the mesocarp fibres after the compressions and macerations at the first and second separation chambers (13, 14). According to one embodiment of the present invention, the first pressing chamber (16) is designed and constructed based on a single axis screw capable of applying pressure onto the mesocarp fibre and feeding the mesocarp fibres through three compression zones. Since kernel nuts are removed during compression and maceration in the previous chambers, nut breakage during pressing is no longer a limiting factor when pressure is applied to extract the remaining crude oil. Although the screw press is configured to impose significantly higher pressure on the mesocarp fibre to remove oil completely, it is not a necessary feature in the present invention as compression and maceration of the mesocarp fibres have been conducted in previous chambers. The complete removal of oil is no longer dependent on the pressure applied onto the mesocarp fibres to burst open oil-bearing cell encapsulated in alpha cellulose in a single pressing operation. When oil-bearing cells are sufficiently macerated in the previous chambers due to the effect of fixed and moveable blade teeth, more cutting and lacerating actions are achieved to liberate oil thereby requiring less power to burst open alpha cellulose encapsulated oil cells to remove oil.

After the first pressing, the mesocarp fibres are discharged dry and relatively oil free. These mesocarp fibres are fed to the hydration chamber (17) comprising a boiling hypotonic solution. During the residence period, oil leaches out of the mesocarp fibre and is released into solution due to the effect of buoyancy and the force of gravity. At the same time, water is absorbed into unbroken cells due to the effect of osmosis and into the void spaces of ruptured or broken cells where oil previously resided. In one embodiment of the present invention, the residence period is preferably 60 minutes. Fibre is mechanically moved vertically through the hydration chamber (17) by hydraulic actuation of a central shaft. Several perforated baffle discs attached to the central shaft within each of the several chambers, more particularly a series of interconnected fabricated cylinders having a number of perforated cylindrical baskets contained within, allow boiling aqueous solution pumped from the recycling and recovery tank (19) to circulate through the system (1) and pass through multiple chamber levels of the hydration chamber (17). The circulation ends in the recycling and recovery tank (19). The perforated baffle discs in each chamber level are positioned in the down position to receive fibres due to the action of the hydraulically actuated cylinder. When the multiple perforated baffle discs attached to the central shaft move vertically upwards, fibres suspended in solution within multiple chambers also move upwards causing a straining effect on the fibre to remove oil attached to the fibre. The oil removed from the fibre is circulated with the solution and is eventually decanted from the solution via the recycling and recovery tank (19). As the fibres in each of the multiple chamber levels of the hydration chamber (17) are brought to the surface when the hydraulic cylinder lifts the perforated baffle discs attached to the central shaft, fibres contained within multiple chambers flow simultaneously over the top of respective chambers due to a tsunami effect imposed on the solution by the rapid vertical movement caused by the hydraulic cylinder. Once the fibres are expelled from one chamber to the next, the hydraulically actuated cylinder returns the perforated baffle discs attached to the central shaft are returned to the down position. Fibres entering at the top of the hydration chamber (17) are finally expelled to the vibrating screen separator after residing in the hydration chamber's boiling hypotonic solution for about 60 minutes. At the vibrating screen separator, which is at the base of the hydration chamber, coarse mesocarp fibres are separated from the solution and discharged to the second pressing chamber (18). Finer non- oily solid fibres are captured in a second vibrating screen separator, which are also discharged to the second pressing chamber (18). Oily aqueous solution is captured in another chamber which it is later decanted to the recycling and recovery tank (19), where oil is decanted, and the aqueous solution is recycled back to the hydration chamber (17). A height sensor is utilized to maintain the level of aqueous solution in the recycling and recovery tank (19) by the actuation of a solenoid operated water valve, thereby allowing fresh water as required to enter the tank (19) accordingly.

As previously mentioned, the recycling and recovery tank (19) is utilized for receiving and recycling the hypotonic solution from and to the hydration chamber (17), and at the same time recovering oil which has leached or removed from the mesocarp fibre during the hydration process (17). In one embodiment, the recycling and recovery tank (19) is a rectangular tank that is partitioned into separate chambers. The first chamber receives aqueous solution from the vibrating screen separator of the hydration chamber (17), as previously described. From this chamber, aqueous solution progresses through a series of obliquely position plates to coalesce the oil particles to a sufficient size so as to allow these oil particles to rise to the surface of the recycling and recovery tank (19) due to the effect of gravity and buoyancy to form an oily top layer which is trapped and decanted as the aqueous solution with its oily top layer passes over the weir baffle towards the discharge chamber for recycling back to the inlet of the hydration chamber or as aqueous solution to be high-pressure sprayed into the second (14) and third (15) separation chambers and the first pressing chamber (16). The hydration process is intended to first facilitate the flow of water into the vacuole of the cell so as to cause an increase in turgid pressure on the cell wall which is needed to optimise the processes in the second pressing chamber (18). Secondly, the process also allows sufficient time for oil to flow out of the ruptured cells due to the influence of gravity and buoyancy. The oil escaping from the ruptured cells subsequently mixes with the hypertonic solution and is subsequently and continuously decanted from the recycling and recovery tank (19) to the oil flow stream.

Moisture laden mesocarp fibres are then discharged from the hydration chamber (17) and fed to the second pressing chamber (18), where the remaining oil and water content are removed from the fibres. Similar to the first pressing chamber (16), the second pressing chamber (18) also comprises a single axis screw responsible for the final pressing of the mesocarp fibres. The mesocarp fibres, after the final compression, is discharged from the system (1) as boiler fuel. From the system (1), crude palm oil is decanted at the base of the first and second separation chambers (13, 14). Oil is also recovered at the base of the first and second pressing chambers (16, 18) and decanted from the recycling and recovery tank (19). All oil streams from the first and second separation chambers (13, 14), first and second pressing chambers (16, 18), recycling and recovery tank (19) are fed to the fourth separation chamber (20). Within the fourth separation chamber

(20), vibrating screen separators are utilized to screen remaining suspended fibres of the fruitlets, specifically those in the crude palm oil. The movement of the vibrating screen separators causes the discharge of the non-oily solids and they are captured and discharged to the bucket elevator

(21) along with the fibres discharged from the first pressing chamber (16). Apart from the weigh hopper (11, 12), chambers (13, 14, 15, 16, 18, 20), tank (19) and bucket elevator (21) in the system (1), one embodiment of the present invention also discloses that the system (1) further comprises a control panel. The control panel is electronically coupled to the weigh hopper (11, 12), chambers (13, 14, 15, 16, 17, 18, 20), tank (19) and bucket elevator (21), mainly to monitor and control the parameters of the system (1). In a more preferred embodiment, the control panel used is preferably Supervisory Control and Data Acquisition, SCADA.

Also disclosed in the present invention is the method for extracting oil from drupe fruits. The method initiates with the feeding of fruitlets into the weigh hopper and intermediate feeder chute (11, 12). As previously mentioned, the weigh hopper and intermediate feeder chute (11, 12) are responsible in determining throughput inconsistencies or variations and facilitate mass balance calculations of the fruitlets. Upon completing this step that involves opening the chute door when a signal is received from the butterfly valve, thereafter discharging the fruitlets into the first separation chamber (13), where the kernel nuts and mesocarp fibres are separated and compressed. The opening signal for the chute door is received when the butterfly valve is in its horizontal position. In the event that the butterfly valve is in its vertical position, the chute door remains closed thereby retaining the fruitlets in the weigh hopper (11) until otherwise instructed. Fruitlets discharged from the intermediate feeder chute (12) into the first separation chamber (13) comprised of a screw barrel and a tapered screw, the fruitlets are compressed, lacerated and macerated to remove oil from the fruitlets. As the fruitlets are conveyed to the second separation chamber (14) which is comprised of a multi-start variable pitch tapered screw within a tapered basket assembly where the fruitlets are further compressed, lacerated and forcedly macerated to extract oil and to strip mesocarp fibres from kernel nuts of the fruitlets respectively. The forces imposed by the tapered multi-start variable pitch screw macerate the fruitlets and expels fibre, oil and water through the basket wall, where high-pressured aqueous solution from the recycled and recovery tank (19) is sprayed to remove them from the basket and separate them at the bottom of the second separation chamber (14).

Thereafter, the fruitlets are discharged into the third separation chamber (15), in which mesocarp fibres are extricated from the surroundings of the palm kernel nuts. At this step, controlled volume of hot water is pressure-injected to remove oil from the kernel nuts and to force fibres through a number of fixed grate blades that are equivalently spaced, allowing passage of oil, fibres and water but retaining kernel nuts of the fruitlets. At the same time, high-pressured aqueous solution from the recycle and recovery tank (19) is sprayed towards the blades to remove remaining oil and fibres attached to the kernel nuts. Oil and water are then decanted while the remaining mesocarp fibres are simultaneously fed to the first pressing chamber (16). In one embodiment of the present invention that is previously mentioned, the feed rates of fruitlets into the first and second separation chambers (13, 14) are monitored and controlled by the load cells and butterfly valve of the weigh hopper and intermediate feeder chute (11, 12). In the event that the butterfly valve remains in horizontal position in a pre-determined time frame, the first, second and third separation chambers (13, 14, 15) are signalled to slow down the rate of maceration of the fruitlets and extrication of the mesocarp fibres as is the first pressing chamber (16). Preferably the rates of maceration, extrication and pressing are slowed down to half of its original rate. In the event that the fruitlets fail to arrive within a pre-determined time frame, the maceration and extrication in the first, second and third separation chambers (13, 14, 15) and pressing in the first pressing chamber (16) will be shut down completely as well as the remaining chambers responsible for feeding and pressing. Conversely, when the butterfly valve moves to its vertical position signalling the resumption of normal fruitlets arrival for a pre-determined time frame, signals for resumption will be sent to all chambers and shut-down procedure will be reversed. The features provided by the butterfly valve and the weigh hopper and intermediate feeder chute (11, 12) herein regulate the flow of fruitlets so that the system (1) provides consistent arrival and appropriate amount of fruitlets based on the volumetric capacity of the system (1) to maximise throughput and minimise power and water consumption.

In the first pressing chamber (16), the mesocarp fibres of the fruitlets are compressed, where up to 95% of oil and water remaining in the mesocarp fibres are removed. The first pressing chamber (16), according to the embodiment of the present invention mentioned earlier, is designed and constructed based on a single axis screw having three compression zones. It should be appreciated that the power of compression required herein is lesser than conventional methods since the kernel nuts are removed during compression and maceration in the previous chambers. With these features, nut breakage during pressing is no longer a limiting factor when pressure is applied to extract the remaining crude oil. It is, therefore, not necessary to impose significantly higher pressure on the mesocarp fibre to burst open oil-bearing cell encapsulated in alpha cellulose to remove oil. After the first pressing, the mesocarp fibres expelled at the base of the single axis screw press of the first pressing chamber (16) are conveyed to the hydration chamber (17) via the bucket elevator (21), in which the hydration chamber (17) soaks the mesocarp fibres from the first pressing in a boiling hypotonic solution to further remove oil from the fibres due to buoyancy, gravitational forces and mechanically, due to the force imposed by the agitation created as the mass of respective counterbalance shift. When the fibres are soaked and agitated in the solution, oil leaches out of and from the outer surface of the mesocarp fibre, eventually separating from the solution. At the same time, water is absorbed into unbroken cells due to the effect of osmosis and into the void spaces of ruptured or broken cells where oil previously resided. Fibre is also mechanically moved vertically through the hydration chamber (17) by hydraulic actuation of a central counterbalanced shaft. Upon soaking, the hypotonic solution is then discharged into the recycling and recovery tank (19), where additional oil is extracted due to the clarifier effect and the remaining aqueous solution is recycled back to the hydration chamber (17) or used as high- pressure aqueous solution spray to separate fibre and kernel nuts in separation chambers (14) and (15) and as additional dilution for the first pressing station (16). In one embodiment, the recycling and recovery tank (19) is a rectangular tank that is partitioned into separate chambers. The first chamber receives aqueous solution from the vibrating screen separator of the hydration chamber (17), as previously described. From this chamber, aqueous solution progresses through a series of obliquely position plates to coalesce the oil particles to a sufficient size so as to allow these oil particles to rise to the surface of the recycling and recovery tank (19) due to the effect of gravity and buoyancy to form an oily top layer which is trapped and decanted as the aqueous solution with its oily top layer passes over the weir baffle towards the discharge chamber for recycling back to the inlet of the hydration chamber (17) or as aqueous solution to be high-pressure sprayed into the second and third separation chambers (14, 15) and the first pressing chamber (16). Subsequently, the mesocarp fibres are fed into the second pressing chamber (18), in which the second pressing chamber (18) further compresses the mesocarp fibres. Similar to the first pressing chamber (15), the second pressing chamber (18) also comprises a single axis screw responsible for the pressing of the mesocarp fibres. The mesocarp fibres, after the final compression, are discharged from the system (1) as boiler fuel. Oil extracted at the second pressing along with the oil extracted at first and second separation chambers (13, 14), first pressing chamber (16), hydration chamber (17), and recycling and recovery tank (19) are fed to the fourth separation chamber (20) to further separate oil and non-oily solids from oil arriving to the fourth separation from all extraction points and oil flow streams. Lastly, the non- oily solids, NOS, from the fourth separation chamber (20), first pressing chamber (16) are discharged into the bucket elevator (21) to begin the hydration process in the hydration chamber (17).

In a preferred embodiment of the present invention, the drupe fruits mentioned throughout the specification refer to oil palm fruits. It should be appreciated by the skilled addressee that the type of drupe fruit is not limited to oil palm fruit, and that the system (1) and method should also be workable in processing other drupe fruits for oil extraction. A further embodiment of the present invention discloses that the weigh hopper and the intermediate feeder chute (11, 12), chambers (13, 14, 15, 16, 17, 18, 20), tank (19) and bucket elevator (21) of the system (1) are assembled in modular frames. The said embodiment discloses that the dimensions of the system (1) comply with typical shipping container dimensions. The frame configurations are combined by 4-way interlocking at each of the corners thereby securing the container frames to form an overall load bearing structure. The configuration of the container structure assembly comprising the container frames is shown in figure 7. The modularisation of each of the feature facilitates considerably faster onsite installation of the extraction system (1), as each of the feature of the system (1) described are configured mechanically and electrically prior to delivery. Additional onsite structure is not required as the assembled structure forms a stand-alone and self-contained single load bearing integrated structure inclusive of electrical wiring, piping, lighting, staircases, safety railings and flooring.

The oil palm industry is familiar with describing milling throughput capacity in increments of 15 FFB tonnes per hour. The modularisation of the features disclosed in the system (1) and method of the present invention aims to maintain the same nomenclature by combining additional system features within a single frame from a minimum of 15 FFB tonnes up to a maximum of 30 FFB tonnes per hour and thereafter together with additional steps of the method in frame modules of 15 or 30 FFB tonne per hour configurations to increase the desired throughput capacity from 15 FFB tonnes per hour increments of 15 FFB tonnes per hour so as to potentially expand the capacity from 15 to 120 tonnes per hour. It should be noted that various configurations can be added together to facilitate a capacity of 45 FFB tonnes per hour or for example 2 x 30 FFB tonnes per hour to facilitate a 60 FFB tonne per hour configuration and so on.

Although only certain exemplary embodiments have been described in detailed above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Additionally, aspects of embodiments disclosed above can be combined in other combinations to form additional embodiments. Accordingly, all such modifications are intended to be included within the scope of this invention.