Centrifugal separation method and plant, namely for the extraction of olive oil

Abstract

In the olive oil production process, a centrifugal separation method of the oil from the solid fraction and from the vegetation water involves recirculating a part of the pomace collected at the respective outlet of the decanter to the inlet of the decanter to introduce it into the decanter together with the olive paste arriving from the malaxation process. The amount of recirculated pomace is determined so as to maintain it constant over time and optimal with respect to the overflow levels set at the beginning of processing, the weight percentage of oil present in the product supplied in input to the decanter even when such a weight percentage varies in the olive paste arriving from the malaxation process due to the differences which can exist between the various batches of olives treated. A centrifugal separation plant adapted to actuate the method of the invention provides at least one centrifugal decanter, means for feeding the olive paste to the decanter, means for collecting the pomace coming out of the decanter and recirculating means for collecting the pomace from the collection means and recirculating it to the inlet of the decanter together with the olive paste. Appropriate sensors and a control unit allow the amount of recirculated pomace to be adjusted so as to keep the percentage by weight of oil present in the product which is introduced into the decanter constant over time.

Description

[0001] “CENTRIFUGAL SEPARATION METHOD AND PLANT, NAMELY FOR THE EXTRACTION OF OLIVE OIL”

[0002] TECHNICAL FIELD

[0003]

[0001] . The object of the present invention is a centrifugal separation plant of the type comprising a decanter, in particular for the separation of olive oil starting from olive paste.

[0004]

[0002] . The present invention further relates to a centrifugal separation method in the olive oil production process.

[0005] STATE OF THE ART

[0006]

[0003] . In the olive oil production process, there is conventionally a step in which the olive paste, previously malaxated to allow the aggregation of the micro-droplets of oil, is treated to separate the oil from the solid fraction and from the vegetation water. The extraction operation, which in the past was obtained by means of discontinuous vertical presses, is today conventionally obtained by centrifugation by means of a horizontal centrifuge, or decanter, in which the oil must (oil containing a residual amount of water, generally in a concentration less than 1%) is separated from the solid fraction and from the vegetation water. The oil must obtained is further cleaned through a second centrifugation step with a vertical centrifuge and / or by means of filtration processes, so as to reduce I remove water and residual solids, still present in the form of emulsion or suspension, respectively.

[0007]

[0004] . Conventionally, a decanter comprises a cylindrically-shaped drum with a frusto- conical end which, set in rotation at high speed, exploits the centrifugal force to separate the components of the olive paste which have different densities. The latter are stratified, arranging themselves on several cylinders coaxial to the drum, or torus: the heavier fractions are arranged on the outermost part, in contact with the walls of the drum, while the lighter fractions will be arranged in the innermost sections. In olive paste, typically, there is a solid phase, which has a density of approximately 1150 kg / m3and constitutes approximately 30% by weight of the paste, an aqueous phase, which has a density of 1010 kg / m3and constitutes approximately 50% by weight of the paste, and an oil phase which has a density of approximately 920 kg / m3and constitutes approximately 20% by weight of the paste. Inside the drum there is a screw conveyor which is rotated at a slightly lower speed with respect to the rotation speed of the drum. The differential speed between the screw conveyor and the drum causes the axial advancement of the solid fraction, which is pushed by the screw conveyor towards the frusto-conical portion (also called the decantation cone) and ejected therefrom. The liquid phases are instead discharged from the cylindrical portion of the drum through openings made on the bottom wall of the drum at an appropriate height, or through radial overflow tubes located at an appropriate height near the bottom of the drum, or even by means centripetal pumps.

[0008]

[0005] . Two main types of decanters are known, depending on the manners in which the different fractions are separated: three-phase decanter, which separates the olive paste into three fractions, namely oil, vegetation water and pomace, consisting of the set of the solid fraction and the residual liquid fractions (mainly water and to a lesser extent oil). This equipment requires a considerable addition of dilution water, up to 50% by mass of the olive paste in input. The addition of dilution water inevitably involves leaching the hydrophilic phenolic compounds present in the olive (also called biophenols), with a consequent reduction of the healthy and organoleptic properties of the oil. two-phase decanter, which separates the olive paste into only two fractions, the oil and a unique mixture of vegetation water, solid fraction and unseparated residual oil, also called wet pomace due to the high water content with respect to the pomace obtained in the three-phase system. Unlike the three-phase decanter, this machine normally does not require added amounts of water, safeguarding the nutritional and organoleptic features of the oils produced, conferred as mentioned by the water-soluble phenolic compounds.

[0009]

[0006] . Currently, the two-phase decanter is the most used type as it is clearly the one which produces the best quality oils due to a greater conservation of the biophenolic component, hoping for greater market prospects.

[0010]

[0007] , There is a problem in the decanters related to the fact that the overflow height, also known as the overflow, discharge or draft level, of the openings, as well as of the discharge pipes of the liquid phases (and in particular that of the oil which is the product of interest) are set according to a rigid configuration, decided at the beginning of the process and not modifiable with the machine in operation. In fact, such levels are possibly only adjustable with the machine stopped after having interrupted the production process, with obvious losses of time and thus of productivity. Such operational reductions are particularly important considering that the operation of these machines is limited during the year to the olive harvest period, ranging from approximately 45 to 60 days.

[0011] The position of the holes or oil discharge pipes in height is an important parameter because if not correctly set, two opposite problems may occur: if it is placed too close to the free surface of the oil torus, there is a loss of oil in the other fractions, i.e., in the pomace by-products and / or vegetation water with a consequent lowering of the extraction yield; if it is placed too close to the oil / water interface (i.e., too far from the free surface of the oil torus), "dirty oil" is extracted, i.e., with a high content of vegetation water, which must necessarily undergo further separation processes. The latter are costly in terms of time and resources, putting the final quality of the oil at risk. When this phenomenon occurs in an extreme manner, an event called "smearing", the decanter is stopped and, once the external casing is opened, the oil drawing level settings are changed.

[0012]

[0008] . The need to adjust the position of the holes or oil discharge pipes in height derives from the fact that the percentage distribution by mass of the components of the olive paste, i.e., the ratio between the percentage of solids, the percentage of vegetation water and the percentage of oil, is not constant but varies according to numerous factors, including at least differences in cultivars, degree of ripeness and agronomic process (irrigation treatments, production area, etc.). The problem of varying the percentage composition of olive paste is particularly felt in the batch processing system, which is that used in many mills which receive small batches of olives from different individual producers, which must be processed in succession separately in order to keep the produced oil separate and return it to the relevant producer.

[0013]

[0009] . Conventionally, to adapt the work of the decanter to the composition variability of the olive paste deriving from batches of different olives and thus obtain an effective separation and an acceptable oil yield, the following operating parameters are acted upon: flow rate of the olive paste feed pump to the decanter and differential speed between the speed of the drum and that of the internal screw conveyor (adjustment present only in some decanter models). Both of these two systems manage to only partially compensate for the problem of the variability of the olive paste in input. They are therefore hardly effective. Reducing the input flow rate allows to increase the permanence of the paste inside the decanter, favouring the separation of the phases, thus improving the degree of purity I cleanliness of the phase of interest, i.e., the oil. On the other hand, such a strategy reduces production capacity and changes the residence time of the paste inside the decanter, increasing the risk of having technological damage on the product due to a longer mechanical action of the machine. Moreover the differential speed, responsible for the transport of the solid part towards the frusto-conical end where it is discharged, must be correctly set both to avoid the transport of the finest solid parts in the liquid phases and to ensure an effective separation of the liquid phases from the solid one. However, both strategies disclosed above remain insufficient to date for an optimal control of the extraction process and in any case not able to allow an effective adaptation of the extraction process to the variabilities which are found between the various batches to be processed.

[0014]

[0010] . A further strategy conventionally adopted in three-phase separation systems is to feed the dilution water entering the decanter more punctually to modulate the height of the water level inside the decanter and thus change the position of the oil level.

[0015]

[0011] . However, there are several disadvantages due to the addition of water. In addition to water consumption, there are obvious negative qualitative effects on the oil obtained. For example, the three-phase decanter requires a considerable addition of water, up to about 50% of the total weight of the paste, causing the dilution of the minor hydrophilic components present in olives, such as phenolic compounds and other antioxidant compounds, responsible for the healthy and nutritional properties of virgin olive oils as well as important organoleptic properties, in particular bitter and spicy notes.

[0016]

[0012] , The three-phase decanter always works with an amount of added water which brings the level of the water ring to a height such as to allow the oil level to be adjusted in both possible directions, i.e. , to increase or decrease the distance of the free surface of the oil from the overflow element. Conversely, the two-phase decanter does not normally envisage the use of paste dilution water, so even a possible addition of water would only allow to increase the thickness of the water ring (increase the distance between the free surface of the oil and the overflow element), but not decrease it.

[0017] SUMMARY OF THE INVENTION

[0018]

[0013] , An object of the present invention is to obviate the drawbacks found with the conventional processing methods and with reference to the state of the art.

[0019]

[0014] . A second object is to propose a centrifugal separation method in the olive oil production process which allows to minimize the oil losses in the by-products, ensuring an acceptable and constant degree of oil cleanliness, despite the variations in the oil I water I solids distribution of the different olive pastes in input to the centrifugal decanter.

[0020]

[0015] , Another object of the invention is to propose a method for separating the oily fraction from the solid fraction and from the vegetation water starting from olive paste which allows to maintain an optimal yield and an optimal quality of the oily fraction even in the presence of frequent variations of the percentage composition of the olive paste in terms of oily, aqueous and solid fractions, as occurs if the mill works batches of different olives.

[0021]

[0016] , It is further an object of the invention to propose a centrifugal separation plant which allows to actuate the centrifugal separation method of the invention to be implemented in a simple and economical manner.

[0022]

[0017] . According to an aspect of the invention, the aforesaid objects are achieved by means of a method according to claim 1.

[0023]

[0018] . A centrifugal separation method according to the present invention comprises steps of:

[0024] Feeding olive paste in which a given flow rate of olive paste is fed to a horizontal centrifuge, or decanter provided with at least one discharge outlet of a solid fraction and at least one discharge outlet of a liquid fraction;

[0025] Separating in said decanter the solid fraction from at least one liquid fraction by applying centrifugal force;

[0026] Collecting the pomace in which the solid fraction coming out from said at least one discharge outlet is collected for the discharge of a solid fraction;

[0027] Collecting the oil must in which at least one liquid fraction is collected coming out of said at least one discharge outlet for discharging a liquid fraction; recirculating the pomace, in which a given flow rate of said collected solid fraction is fed to said decanter together with said given flow rate of olive paste; in which the flow rate of olive paste fed to the decanter in the feeding step and the flow rate of pomace fed to the decanter in the recirculating step are adjusted to keep constant, and optimal with respect to the overflow levels set at the beginning of processing, the weight percentage amount of the oil fraction in the input product to said decanter, in which the input product is defined as the whole of the olive paste fed in the feeding step and the pomace fed in the recirculating step.

[0028]

[0019] . Advantageously, the flow rate of olive paste fed to the decanter and the flow rate of recirculated pomace in input to the decanter are adjusted so as to keep the total flow rate of product to be separated fed to the decanter constant, as set at the beginning of processing.

[0029]

[0020] . The method of the invention essentially involves recirculating a given amount of the pomace separated in the decanter, to the decanter itself, to keep the percentage of the oily fraction in the product to be separated which is introduced into the decanter as constant as possible over time.

[0030]

[0021] , The method of the invention involves in particular recirculating a given amount of the pomace separated in the decanter, to the decanter itself, to keep the percentage of the oily fraction in the product to be separated which is introduced into the decanter as optimal as possible with respect to the set overflow levels.

[0031]

[0022] . Trying to feed the decanter with an olive paste which has a constant oil I water I solids distribution allows to minimize the oil losses in the by-products, ensuring an acceptable degree of oil cleanliness while varying the oil I water I solids distribution of the different olive pastes in input to the centrifugal decanter. Such a result is obtained by mixing the input paste with a part of the output pomace in a continuous and modulated manner so as to compensate for the variations in the composition of the input olive pastes.

[0032]

[0023] . Furthermore, keeping the composition of the input product to the decanter as constant as possible, in particular as a ratio between the oily fraction and the remaining solid fraction and vegetation water, means that there is no longer the need to adjust the oil discharge I draw levels to keep them at an optimal level, i.e., at a level such as to minimize oil losses in the pomace and obtain a sufficiently clean oil when the composition of the batches of processed olives varies. In essence, instead of adjusting the level of the oil discharge outlets, the percentage of oily fraction in input to the decanter remains constant even when it is different in the input olive paste, so that the ring of oily fraction inside the decanter is maintained at a constant and optimal level with respect to the overflow levels set at the beginning of processing.

[0033]

[0024] , In an embodiment of the invention, between the step of collecting the pomace and the step of recirculating the collected pomace to the decanter, there is a step of storing the collected pomace in an inert atmosphere in which it is envisaged to prevent the contact of the collected pomace with air to avoid the occurrence of oxidative processes.

[0034]

[0025] , In an embodiment of the invention, the method of the invention comprises a step of detecting the chemical and physical properties of the liquid fraction (oil must) collected in said step of collecting the oil must and / or of the pomace collected in said step of collecting the pomace and a step of automatically adjusting the flow rate of the olive paste fed in said step of feeding the olive paste and / or the flow rate of the collected pomace fed in said step of recirculating the pomace according to the data collected in said step of detecting.

[0035]

[0026] . According to another aspect of the present invention, the aforementioned objects are achieved by means of a centrifugal separation plant according to claim 5.

[0036]

[0027] , A centrifugal separation plant according to the invention comprises: at least one decanter comprising: o a drum mounted revolving about a substantially horizontal axis, said drum being suitable for being brought into rotation at high speed so as to realize a centrifugal force that permits the centrifugal separation by stratification of a solid fraction and at least one liquid fraction; o at least one inlet to feed to the drum a product to be separated into said solid fraction and at least one liquid fraction; o at least one first outlet for the exit of the pomace from the drum, comprising said solid fraction (higher density component); o at least one second outlet for the exit from the drum of said at least one liquid fraction (lower density component); o at least one screw conveyor comprising a shaft rotatably mounted within the drum and provided with at least one helical blade arranged to push the solid fraction towards the first outlet; feed means arranged to feed the product to be separated to the inlet opening of the decanter; a collection container arranged to receive the pomace leaving said first outlet of the decanter; recirculation means arranged to take the pomace in output from the collection container and feed it to the inlet opening of the decanter.

[0037]

[0028] . According to an embodiment, the plant of the invention comprises: at least one sensor for detecting the chemical and physical properties of the liquid fraction exiting said second outlet and / or of the pomace exiting said first outlet; a control unit configured to control said feed pump and / or said recirculation pump based on the information received from said at least one sensor.

[0038]

[0029] . Advantageously, the at least one sensor comprises a turbidimeter configured for detecting the turbidity of the oil must exiting said second outlet.

[0039]

[0030] . Still advantageously, the at least one sensor comprises a colorimeter configured for detecting changes in color of the oil must exiting said second outlet.

[0040]

[0031] , Still advantageously, the at least one sensor comprises a spectroscopic detector configured for detecting the fat percentage present in the pomace exiting said first outlet of the decanter.

[0041]

[0032] . Still advantageously, the at least one sensor comprises an amperometric or voltammetric detector configured for detecting the fat or water percentage present in the pomace exiting said first outlet of the decanter.

[0042]

[0033] . According to an embodiment, the decanter comprises a first motor configured for actuating the drum rotation and a second motor configured for actuating the shaft rotation, said control unit being configured for controlling the rotation speed of said second motor to adjust the speed gradient between said drum and said shaft according to the information received from said at least one sensor.

[0043]

[0034] . According to an embodiment, the collection container is closed airtight and the plant provides means for feeding a technical gas into the pomace collection container. DESCRIPTION OF THE DRAWINGS

[0044]

[0035] . Further features and advantages of the invention will appear from the description below of embodiments, given by way of example and not limitation, with reference to the accompanying figures, in which:

[0045] - figure 1 shows a partial longitudinal sectional view of a decanter of the type used in a plant according to the present invention;

[0046] - figure 2 shows a schematic top view of a plant according to the present invention;

[0047] - figure 3 shows a schematic front view of a plant according to the present invention.

[0048] - figure 4 shows a flow chart of a method according to the present invention.

[0049] DESCRIPTION OF PREFERRED EMBODIMENTS

[0050]

[0036] . According to a general embodiment and with reference to figure 1 , a centrifugal separation plant according to the invention comprises a horizontal centrifuge, or decanter, 10, for example with two phases.

[0051]

[0037] , The decanter 10 comprises a drum, 11 , internally hollow of substantially frusto-conical shape, with a cylindrical portion, 11a, and a frusto-conical portion, 11b, connected to each other in an intermediate zone of the drum 10. The drum 10 is rotatably mounted with respect to a horizontal axis, X.

[0052]

[0038] . The product to be separated, P, is fed into the drum 10 by means of an adduction duct, 12, axially arranged to enter from a lower diameter end, 10a, of the drum and open into an inlet, 13, placed in a longitudinally (the axial direction) intermediate zone of the drum 10.

[0053]

[0039] . When the drum is rotated by appropriate motion transmission means, 14, connected to a first motor (not shown), the solid fraction S, is arranged peripherally against the wall of the drum 10, while the liquid fraction, L, lighter than the solid fraction, is arranged more internally, closer to the rotation axis X.

[0054]

[0040] . A screw conveyor, 15, is housed inside the drum 10, which comprises a hollow shaft, 16, rotatably mounted coaxial to the drum 10 and a helical blade, 17, which has a dimension such that the outer edge of the blade is located near the wall of the drum. The screw conveyor is brought into rotation by motion transmission means, 18, connected to a second motor, M2 (schematically indicated in figure 2). The drum 10 and the screw conveyor 15 are placed in rotation at different speeds so that the speed gradient causes the blade 17 of the screw conveyor to push the solid fraction S towards the lower diameter end, 19, of the drum at which there is a first outlet, 20, which allows the exit of the pomace from the drum 10. The liquid phase L flows out from a second outlet, 21, located at the larger diameter end, 22, of the drum 10 at a distance appropriately determined from the axis X.

[0055]

[0041] . It should be noted that in the above-described embodiment of a two-phase decanter for the production of olive oil, the pomace includes the solid fraction S and the vegetation water, while the liquid fraction L comprises the oil must, composed of oil and, to a lesser extent, water in concentrations generally less than 1%.

[0056]

[0042] , With reference also to figures 2 and 3, the decanter 10 is inserted in a centrifugal separation plant intended to separate the oil must starting from olive paste coming from a malaxation process. The plant 100 comprises, in addition to the decanter 10, feed means, 30, arranged to feed olive paste through a feed duct, 31 , to the adduction duct 12 and then to the inlet opening 13 of the decanter. The plant 100 further comprises a collection container, 40, arranged to receive the pomace ejected from the drum 10 through the first outlet 20. To the collection container 40 there are operatively connected recirculation means, 50, arranged to receive the pomace from the container 40 and feed it through a recirculation duct, 51 , to the adduction duct 12 and then to the inlet opening 13 of the drum 10. A recirculation manifold, 52, is operatively connected to the adduction duct 12, to the feed duct 31 and to the recirculation duct 51 to allow the mixing of the olive paste with the pomace before the product to be separated P reaches the inlet opening 13 of the drum 10.

[0057]

[0043] . Discharge means, 60, are operatively associated with the collection container 40 to expel the pomace which is not recirculated from the plant.

[0058]

[0044] . A first flow meter, 32, and a second flow meter, 53, are operatively connected to the feed duct 31 and to the recirculation duct 52, respectively. Furthermore, a turbidimeter, 70, is operatively associated with the second outlet, 21, to detect the turbidity, and thus indirectly the percentage content of vegetation water in the oil must in output from the decanter. A control unit, 80, is operatively associated with the second motor, M2, the feed means 30, to the recirculation means 50, the turbidimeter 70, the first flow meter 32 and the second flow meter 53. The control unit 80 is configured to control the second motor M2, the feed means 30 and the recirculation means 50 on the basis of the information received from the sensors, i.e. , from the flow meters 32 and 53 and from the turbidimeter 70.

[0059]

[0045] . In an embodiment variant, the turbidimeter 70 can be replaced by a colorimeter suitable for detecting changes in the color of the oil must in output from said second outlet 21.

[0046] . Advantageously, a spectrophotometer is also provided operatively associated with the first outlet 20 to measure the percentage of oil present in the pomace in output, with the control unit 80 configured to operate also according to this information.

[0060]

[0047] , In an embodiment variant, instead of or in addition to the spectrophotometer, an amperometric or voltammetric detector can be provided which is configured for detecting the percentage of fat or water present in the pomace exiting said first outlet 20 of the decanter.

[0061]

[0048] . In an embodiment variant, not shown, the collection container 40 is closed airtight and the plant provides means for feeding a technical gas inside the collection container 40 to prevent the pomace from undergoing oxidative processes due to contact with air.

[0062]

[0049] . A plant according to the invention, as described above, allows to actuate a centrifugal separation method according to the invention.

[0063]

[0050] . With reference to figure 4, the centrifugal separation method envisages feeding, 110, olive paste to a horizontal centrifuge 10 provided with at least a first outlet 20 for discharging the pomace, comprising the solid fraction S and the vegetation water, at least a second outlet 21 for discharging of a liquid fraction L (oil must). In the centrifuge 10, a step occurs of separating, 120, the solid fraction S from at least one liquid fraction L by applying centrifugal force in conventionally known manners. Following the step of separating 120, a step occurs of collecting the pomace, 130, in which the solid fraction S coming out of the first outlet 20 is collected and a step of collecting the oil must, 140, in which at least one liquid fraction L in output from the second output 21 is collected. Finally, the method provides a recirculation step, 150, in which a certain flow rate of the collected pomace is fed to the centrifuge 10 together with the olive paste so that the centrifuge 10 is fed with a mixture of olive paste and pomace.

[0064]

[0051] , The method envisages that the flow rate of olive paste fed to the decanter in the feeding step 110 and the flow rate of pomace fed to the decanter 10 in the recirculation step 150 are adjusted, step 170, to maintain the total flow rate of product P fed to the decanter 10 constant and also so as to maintain the weight percentage of the oil fraction in the product in input to said decanter constant over time.

[0065]

[0052] , The method envisages steps of detecting, 160, to detect the chemical physical properties of the liquid fraction collected in said step of collecting the oil must 140 and / or the pomace collected in said step of collecting the pomace and a step of automatically adjusting, 170, the flow rate of the olive paste fed in said step of feeding olive paste and / or the flow rate of pomace fed in said recirculation step 150 according to the data collected in the step of detecting 160.

[0066]

[0053] . In an embodiment variant of the method of the invention, between the step of collecting the pomace 130 and the step of recirculating the pomace 150, there is a step of storing the collected pomace in an inert atmosphere in which it is envisaged to prevent the contact of the collected pomace with air to avoid the onset of oxidative processes.

[0067]

[0054] . According to an embodiment of the method of the invention, given a certain feed flow rate, characteristic of the centrifugal decanter, the method of the invention envisages starting the processing of the paste with a percentage of recirculating pomace to be mixed with the paste from the previous malaxation step, in an indicative (but not binding) percentage of 10- 20%. Such a modality brings two main effects: i) the reduction of the operating capacity of the decanter which processes a smaller amount of paste with respect to conventional processing; ii) the possibility of increasing or decreasing the amount of recirculated pomace and therefore of continuously varying the oil I water I solids composition in input to the decanter, keeping it generally constant. The increase or decrease in the recirculated pomace obviously involves a variation in the composition of the product in input to the decanter, as the pomace has an oil I water I solids distribution significantly different from that of the paste in input. In particular, by increasing the amount of recirculated pomace, the oil I water interface inside the decanter is moved internally, in a radial direction, while by decreasing it, it is moved to the outermost position. This is evidently due to the fact that there is a much smaller amount of oil in the pomace, about 2%, with respect to the percentage of oil present in the paste to be extracted.

[0055] . The centrifugal separation method of the invention is particularly advantageous where the batch processing system is adopted. Where this processing system is adopted, in fact, the feeding to the decanter of an olive paste which has a very variable composition over time often occurs due to the differences between the individual batches of olives given to the mill. For each batch of olives, the operating settings of the decanter should be modified and adjusted to the features of each batch of olives. However, this is not possible, as it would be necessary to frequently stop the decanter with unsustainable productivity losses.

[0068]

[0056] . The method of the invention instead allows to make changes to the mechanical configuration of the decanter unnecessary, homogenising the chemical physical properties of the product in input over time by adjusting the ratio between the olive paste and the recirculated pomace which compose it. Furthermore, through the recirculation of the pomace, the addition of water can also be avoided with consequent water saving and safeguarding the minor polar components of the oil which would otherwise have to undergo a leaching process with consequent depletion of the healthy and organoleptic features of the product.

[0069]

[0057] , With the method of the invention, the organoleptic qualities of the oil must have not worsened with respect to those obtained with a conventional process, as the pomace is recirculated immediately before degradation processes can be triggered. To guarantee this aspect, the method of the invention advantageously envisages a preservation of the pomace, however brief, in a conditioned atmosphere.

[0070]

[0058] . Of course, the combinations of features of the appended claims form an integral and integrated part of the present disclosure.

[0071] A person skilled in the art can make numerous modifications, adaptations and replacement of elements with functionally equivalent elements to the embodiments described above, without however departing from the scope of the appended claims.

Claims

CLAIMS1. Centrifugal separation method including steps of:- feeding (110) olive paste, in which a given flow rate of olive paste is fed to a horizontal centrifuge, or decanter (10), provided with at least a first discharge outlet (20) of a solid fraction (S) and at least a second discharge outlet (21) of a liquid fraction (L);- separating (120), in said decanter (10), the solid fraction (S) from at least one liquid fraction (L) by applying centrifugal force;- collecting the pomace (130), in which the solid fraction (S) coming out of said at least one first discharge outlet (20) is collected for the discharge of a solid fraction (S);- collecting the oil must (140), in which at least one liquid fraction (L) is collected coming out of said at least one second discharge outlet (21) for discharging the liquid fraction (L);- recirculating pomace (150), in which a given flow rate of said collected pomace is fed to said decanter (10) together with said given flow rate of olive paste of said feeding phase (110); in which the flow rate of olive paste fed to the decanter (10) in the feeding phase (110) and the flow rate of pomace fed to the decanter (10) in the recirculating phase (150) are adjusted to keep constant the weight percentage of the oil fraction in the input product (P) to said decanter (10), said input product (P) being the whole of the olive paste fed to the decanter (10) in the feeding phase (110) and the pomace fed to the decanter (10) in the recirculating phase (150).

2. Centrifugal separation method according to claim 1 characterized in that the flow rate of olive paste fed to the decanter (10) and the r pomace flow rate recirculated at the inlet of the decanter (10) are adjusted in such a way that the total flow rate of product to be separated (P) fed to the decanter (10) is kept constant.

3. Centrifugal separation method according to claim 1 or 2 characterized in that it comprises a step of detecting (160) chemical and physical properties of the liquid fraction (L) collected in said step of collecting the oil must (140) and / or of the pomace collected in said step of collecting the pomace (130) and a step of automatically adjusting the flow rate of the olive paste fed in said step of feeding (110) and / or the flow rate of pomace fed to the decanter in said step of recirculating (150) according to the data collected in said step of detecting (160).

4. Centrifugal separation method according to one of the previous claims characterized in that between the step of collecting the pomace (130) and the step of recirculating (150) the collected pomace to the decanter (10) there is a step of storing the collected pomace in an inert atmosphere so as to prevent contact of the collected pomace with air and thus the occurrence of oxidative processes.

5. Centrifugal separation plant (100) comprising:- at least one decanter (10) comprising: a drum (11) mounted revolving about a substantially horizontal axis (X), said drum (11) being suitable for being brought into rotation at high speed so as to realize a centrifugal force that permits centrifugal separation by stratification of a solid fraction (S) and at least one liquid fraction (L); at least one inlet (13) to feed to the drum (11) a product to be separated (P); at least a first outlet (20) for the exit from the drum (11) of said solid fraction (S);at least a second outlet (21) for the exit from the drum (11) of said at least one liquid fraction (L); at least one screw conveyor (15) comprising a shaft (16) rotatably mounted within the drum (11) and provided with at least one helical blade (17) arranged to push the solid fraction (S) towards the first outlet (20);- feed means (30) arranged to feed the product to be separated (P) to the inlet opening (13) of the decanter;- a collection container (40) arranged to receive the pomace leaving said first outlet (20) of the decanter (10);- recirculation means (50) arranged to take the pomace from the collection container (40) and feed it to the inlet opening (13) of the decanter (10).

6. Centrifugal separation plant (100) according to the preceding claim, characterized in that it comprises:- at least one sensor for detecting chemical and physical properties of the liquid fraction (L) exiting said second outlet (21) and / or the pomace exiting said first outlet (20);- a control unit (80) configured to control said feed means (30) and / or said recirculation means (50) based on information received from said at least one sensor.

7. Centrifugal separation plant (100) according to the preceding claim characterized in that said at least one sensor includes a turbidimeter (70) configured for detecting the turbidity of the oil must exiting said second outlet (21).

8. Centrifugal separation plant (100) according to claim 6 or 7 characterized in that said at least one sensor includes a colorimeter configured for detecting changes in color of the oil must exiting said second outlet (21).

9. Centrifugal separation plant (100) according to claim 6 or followings, characterized in that said at least one sensor includes a spectroscopic detector configured for detecting the fat percentage of the pomace exiting said first outlet (20) of the decanter (10).

10. Centrifugal separation plant (100) according to claim 6 or followings, characterized in that said at least one sensor includes an amperometric or voltammetric detector configured for detecting the fat or water percentage of the pomace exiting said first outlet (20) of the decanter.

11. Centrifugal separation plant (100) according to claim 6 or followings, characterized in that said decanter (10) comprises a first motor configured for actuating the drum (11) rotation and a second motor (M2) configured for actuating the shaft (15) rotation, said control unit (80) being configured for controlling the speed of said second motor (M2) to adjust the speed gradient between said drum (11) and said shaft (15) according to information received from said at least one sensor.

12. Centrifugal separation plant (100) according to claim 6 or followings, characterized in that said collection container (40) is closed airtight and said plant (100) comprises means for supplying at least one technical gas to said collection container (40).

Images