EP0600886A1

EP0600886A1 - Squeezer, in particular for extracting cocoa butter

Info

Publication number: EP0600886A1
Application number: EP92903206A
Authority: EP
Inventors: Antonio Bifaro; Amedeo Caccia Dominioni; Ottorino Chiappa; Gianfranco Favero; Franco Fedriga; Giancarlo Via Clarice Tartufari 161 Salvi
Original assignee: Servco SpA
Current assignee: Servco SpA
Priority date: 1991-01-21
Filing date: 1992-01-20
Publication date: 1994-06-15
Also published as: WO1992012853A1

Abstract

Dans le but d'augmenter la productivité d'une presse à pots pour presser les oléagineux, notamment une masse de cacao, sans augmenter le nombre ou le diamètre des chambres de pressage (1), des moyens additionnels sont prévus pour augmenter la surface des éléments filtrants placés sur les parois des chambres (1). En particulier, les parois frontales (15a, 16a) de chaque chambre (1) ont une superficie accrue grâce à une forme non plane, par exemple hémisphérique, tronconique ou sinueuse. Des éléments filtrants additionnels peuvent être prévus sur la paroi périphérique cylindrique (10) de chaque chambre.In order to increase the productivity of a pot press for pressing oilseeds, in particular a cocoa mass, without increasing the number or the diameter of the pressing chambers (1), additional means are provided to increase the surface of the filter elements placed on the walls of the chambers (1). In particular, the front walls (15a, 16a) of each chamber (1) have an increased surface area thanks to a non-planar shape, for example hemispherical, frustoconical or sinuous. Additional filter elements can be provided on the cylindrical peripheral wall (10) of each chamber.

Description

JAR PRESS, ESPECIALLY FOR THE EXTRACTION OF COCOA BUTTER

The present invention relates to a pot press for the extraction of a liquid fraction from a mass, in particular for the extraction of cocoa butter, comprising at least one pressing chamber having a peripheral wall and two opposite front walls. one to the other, these front walls being formed by filter elements mounted on a pair of opposite plates, at least one of which is movable in an axial direction of the chamber, loading means for introducing said mass into a chamber pressing, liquid discharge conduits in the plates, and hydraulic pressing means arranged to press towards each other, in an axial direction, said plates so as to apply to the mass a pressure tending to pass said liquid fraction through the filter elements.

Jar presses are used mainly to press strongly, but gradually, masses of food or chemical products including solid and liquid fractions. One of the most widespread applications is the hot pressing of a mass of finely ground cocoa, also known as cocoa mass or pure paste in the chocolate industry. By heating to about 80 to 100 ° C, the fatty fraction, called cocoa butter and representing about 55% of the mass, is liquefied and most of it can be extracted by pressing through filter elements. This technique and a pot press for the extraction of cocoa butter are described in particular by H. FINCKE in "Handbuch der Kakaoerzeugnisse", 2. Auflage, 1965, p. 167-175.

In this type of application, the productivity of the presses is limited by the relatively low filtration speed of the liquid and by the need to apply the pressure in a progressive manner in order to avoid excessive heating of the mass and / or the liquid. It is

REPLACEMENT SHEET why we use jars or pressing chambers whose axial length (for example about 10 cm) is much smaller than the diameter (for example about 4-0 cm), so that the area of the filter elements on the front faces is relatively great for a given volume of the pot. With these arrangements, it is currently possible to carry out approximately four pressing operations per hour, leaving only 10-12% fat in the cake. In the current state of the art, in order to substantially increase the productivity of cocoa presses, one must be content to multiply the number of jars, with a corresponding increase in the size, weight and cost of the press. In addition, this method also increases the stroke of the hydraulic pressing cylinder.

In presses of different kinds, it has already been proposed to increase the surface of the filter elements by adding protruding elements on the front walls of two opposite plates. For example, French patent No. 714-'14-1 shows permeable wedge-shaped elements on the platens of a grape press, and German patent No. 273 '138 shows a peat press of which at least one tray is bristling with perforated conical points. Constructions of this kind are incompatible with the very high pressures prevailing in a pot press. In addition, they require a considerable distance between the plates at the end of the pressing, which is not admissible in a pot press.

French Patent No. 661 * 782 describes a hydraulic press usable for pressing oil seeds and having a pressing chamber with rectangular cross section. Each front wall of this chamber and the adjacent lateral zones comprise four flat filtering surfaces which are strongly inclined with respect to the axis of the press and are arranged in a zig-zag fashion to form corners. These surfaces are formed by flat plates shouldered by transverse ribs of the frame and the movable platform of the press. It appears that such a rectangular section press is not able to withstand the pressures of current pot presses, that is to say that it is another type of press. In addition, the chamber length is much too large and therefore determines too large a chamber volume.

The present invention aims to improve a pot press of the type indicated in the preamble, so as to increase its productivity without increasing the number or size of the pressing chambers.

For this purpose, a first aspect of the invention relates to a press characterized in that the front walls of each pressing chamber have a generally circular shape which deviates substantially from a plane, one of these walls having a shape convex over at least part of its extent, and the other a corresponding concave shape, and in that said general shape of the front walls comprises at least a portion of one of the following geometric shapes: half-sphere, spherical cap, trunk cone, torus.

In a particular embodiment, said convex and concave shapes are hemispheres or spherical caps whose respective centers substantially coincide in an end-of-travel position of the press, so that the radial distance between the two opposite front walls the extent of these walls in said position is substantially the same on the road. In another embodiment, said convex and concave shapes correspond so that the axial distance between the two opposite front walls is substantially the same over the entire extent of these walls.

Said general non-planar shape of the front walls may comprise a central portion of planar surface, surrounded by a portion of non-planar surface. One of the filter elements may have surface undulations on a surface portion with a convex, concave or planar shape.

In addition, the cylindrical peripheral wall of each pressing chamber may comprise at least one filter element and conduits

REPLACEMENT SHEET liquid discharge on the back of this filter element.

In an advantageous form of the invention, the filter elements include porous sintered metal plates. In particular, it is possible to provide that at least one of the filter elements of the front walls is made of a single porous plate of sintered metal.

The present invention and its advantages will be better understood with the aid of the following description of various embodiments, presented below by way of nonlimiting examples and with reference to the appended drawings, in which:

fig. 1 is a schematic view in partial longitudinal section of a cocoa press with four jars according to the invention,

fig. 2 shows in more detail a part of the object of FIG. 1 and schematically shows the structure of the pots and the trays separating them,

fig. 3 to 7 schematically represent, in axial section, different shapes of circular pots having front walls whose shape deviates from a plane, and

fig. 8 is a view in longitudinal section similar to FIG. 2, showing an example of pots with hemispherical front walls.

The cocoa press shown in figs. 1 and 2 is a horizontal press of the Carver type, having four identical circular pots 1 which are aligned on a horizontal axis 2. A frame 3 of the press comprises a main head and a secondary head 5 which are rigidly connected by bars traction 6 parallel to the axis 2. The main head 4- contains a hydraulic pressing cylinder, formed by an axial piston 7 and a pressure chamber 8 connected in known manner to a hydraulic pressure source 9- The pressing chambers 1 are delimited by annular bodies 11, having internally a cylindrical surface 10 which forms the

REPLACEMENT SHEET peripheral wall of each chamber, and by intermediate 12 and terminal plates 13, 14- whose mutually opposite faces form the front faces 15, 16 of each chamber 1. The terminal plate 14- is fixed to the frame 3. The others plates 12, 13 and the annular bodies 11 are mounted on the bars 6 so as to be able to slide longitudinally to vary the volume of the chambers 1, the annular bodies 11 themselves being arranged to slide on corresponding cylindrical parts of the plates 12, 13, 14. Compression springs 17 are provided to hold each body 11 in a stop position (to the left in the position of FIG. 1) during the pressing operations, and small hydraulic cylinders (not shown) are provided to push the annular bodies 11 in the opposite direction to open each chamber 1 to allow it to be emptied. Each annular body 11 is connected by a supply line 20 to a loading device 21 arranged to fill the chambers 1 with a mass of hot and liquid cocoa, by pumping metered quantities. The trays 12, 13, 14 are provided with filter elements 23, 24 on their front faces and, behind these elements, they contain a network of liquid discharge channels 25 and 26 allowing the cocoa butter to flow, in particular by gravity, up to an external collector 27 leading to a reservoir 28.

This principle of press construction is known and its operation is described in particular in the manual by H. Fincke mentioned above. The main stages of operation are as follows:

a) loading of metered quantities of the mass into chambers 1;

b) optionally, maintaining the mass under a pressure imposed by the loading device 21, to perform a first filtration and increase the load of each pot;

c) progressive introduction of hydraulic pressure into the chamber 8 to effect pressing by means of the piston 7, and simultaneous control of the quantity of liquid obtained;

d) after obtaining the desired degree of pressing, retraction of the piston 7 and of the annular bodies 11 to open the pots and take out the cakes,

e) closing the jars to start a new pressing cycle.

An improvement in the operating method of the press consists in applying a vacuum in the discharge conduits 25, 26 in order to accelerate the passage of the liquid through the elements 23, 24, especially at the start of pressing (phases b and / or vs) . For this purpose, the reservoir 28 can be closed and connected to a vacuum source 30 capable of providing a vacuum to about 0, 75xl0 ^Ξ Pa, via a control valve 31. This leads to increase the productivity of the machine by approximately 5 to 10%. Another advantage of this technique is that it can easily be implemented on existing presses.

In the press illustrated in figs. 1 and 2, another improvement increasing productivity consists in increasing the filtering surface of each pot by means of filtering elements 32 installed in the annular bodies 11 and occupying approximately half the length of the circular peripheral surface 10 of each chamber 1. Evacuation conduits 33, 34, similar to conduits 25, 26, are arranged on the back of the filter elements 32 and are connected to the manifold 27, so that vacuum can also be applied to them. The filter elements 32 make it possible to increase the filtration surface up to 30% and thus reduce the duration of a pressing cycle.

Another arrangement making it possible to increase the filtration surface without changing the main dimensions of the press and in particular those of the chambers 1, of the piston 7 and of the plates 12 to 14, consists in giving a non-planar shape to the front surfaces 15, 16 of each chamber 1. In this way, the filtration surface is increased compared to that of the usual flat walls, without

REPLACEMENT SHEET changing the capacity of each chamber, so that the duration of a pressing cycle is reduced. Figs. 3 to 7 are diagrams in axial section illustrating different non-planar circular shapes of the front walls 15a-15e and I6a-l6e of a pressing chamber.

In the example of fig. 3, the front wall 15a has a concave shape in a spherical cap of radius RI, while the wall 16a has a convex shape in a spherical cap of radius R2. When the radii R1 and R2 are equal, the axial distance between the two walls 15a and 16a is the same over their entire extent. However, it may be advantageous to use different radii, giving a radial spacing E approximately equal over the entire extent of the wall 15a at the end of pressing, in order to have more uniform conditions throughout the mass. This is the case with the construction shown in Figure 2.

In the example of fig. 4, the front walls 15b and 16b of the chamber 1 both have the same conical shape. In this way, the axial spacing A between the two walls is the same throughout the chamber, in order to ensure pressing as uniform as in the case of flat walls.

In the case of fig. 5, each of the front walls 15c and 16c of the chamber 1 consists of a frustoconical surface portion 41, 42 and a central portion of planar surface 43, 44. With respect to the example of FIG. 4, this shape gives a cake which is less bulky and therefore easier to evacuate, without significant reduction in the filtration surface.

In the example of fig. 6, the two front walls 15d and 16d have a sinuous profile in the radial direction and therefore each comprise a concave portion and a convex portion. The wall 15d has a convex central portion 45 in a spherical cap surrounded by a concave portion 46 of toroidal shape. Opposite, the wall 16d has a concave spherical central portion 47 surrounded by a convex toric portion 48. This profile allows a significant increase in the filtration surface, with a relatively small increase in

REPLACEMENT SHEET the size of the meal. In another embodiment of the invention, instead of being sinuous in the radial direction, the profile of the front walls could be sinuous in the circumferential direction.

Fig. 7 schematically illustrates the example of a pressing chamber 1 of generally hemispherical shape. The concave front wall 15e is hemispherical and is extended directly by a cylindrical surface 10e forming the peripheral wall of the chamber. The surface of the convex front wall 16e includes a hemispherical main portion 51 and a flat annular portion 52 surrounding the latter. In the drawing, there is shown in solid lines the relative position of the two walls 15th, 16th when filling chamber 1, and in dashed lines the relative position of the wall 16th at the end of pressing, where the cake has preferably an approximately uniform thickness corresponding to the radial spacing E between the walls in this position where the centers of curvature of the two walls coincide. As E is equal to the difference between the respective radii RI and R2 of the 15th and 16th walls, the choice of R2 for a given value of RI will depend on the degree of pressing to be obtained, i.e. the fat content oil cake.

This limitation generally does not exist in the case of FIG. 3. On the other hand, the hemispherical shape according to fig. 7 allows a greater increase (about 80%) of the filtering surface compared to the case of flat walls.

Fig. 8 shows an example of construction of hemispherical chambers according to the principle of FIG. 7. Elements similar to those of FIG. 2 have the same reference numbers.

On the portions of non-planar surfaces of the walls 10, 15 and 16 in the various examples described above, the construction of the filter elements can generally be the same as that of the usual planar elements, in particular elements composed of metal mesh on plates perforated. You can also replace the trellis with microperforation plates or with plates

REPLACEMENT SHEET porous sintered, especially if the geometry of the surface has a strong curvature. In addition, the filter elements may also have small undulations over their entire extent in order to further increase the filtration surface, in a manner already known and used in filter elements of generally planar shape.

The filter elements 23, 24 and 33 shown in Figs. 2 and 8 are preferably sintered permeable parts, manufactured in a known manner in the field of powder metallurgy. Indeed, the usual filter elements made of metallic fabric are difficult to adapt to surfaces with a large curvature. In current presses with flat front walls, they are the elements subject to the most wear, and this effect would be further accentuated on strongly inclined surfaces, for example on hemispherical walls. The use of curved sintered plates avoids this kind of drawback. In addition, wire mesh presents other problems in pot presses. They are expensive because each filter element generally comprises several superimposed fabrics, the meshes of which have different respective sizes, and it is necessary to change all these fabrics when one of them is worn or damaged. The fabrics must be made of stainless steel, but this must be magnetized and therefore more expensive, so that any metallic waste can be removed from the oil cakes by means of electromagnets. In sintered filter elements, the mechanical stresses are lower than in wire mesh and there is therefore greater freedom in the choice of materials.

Although the above description refers to the example of a cocoa press, the present invention extends in general to all the applications of pot presses, for hot or cold pressing .

REPLACEMENT SHEET

Claims

1. Jar press for extracting a liquid fraction from a mass, in particular for extracting cocoa butter, comprising at least one pressing chamber (1) having a peripheral wall and two front walls (15, 16) opposite one another, these front walls being formed by filter elements (23, 24) mounted on a pair of opposite plates (12, 13, 14) at least one of which is movable in one direction axial of the chamber, loading means (20, 21) for introducing said mass into a pressing chamber, conduits (25, 26) for discharging liquid in the plates, and hydraulic pressing means (7, 8 , 9) arranged to press one towards the other, in an axial direction, said plates so as to apply to the mass a pressure tending to pass said liquid fraction through the filter elements, characterized in that the front walls ( 15, 16) of each pressing chamber (1) have a general shape cir circular which deviates substantially from a plane, one of these walls having a convex shape over at least part of its extent, and the other a corresponding concave shape, and in that said general shape of the front walls comprises at least a portion of one of the following geometric shapes: half-sphere, spherical cap, truncated cone, torus.

2. Press according to claim 1, characterized in that said convex and concave shapes are half-spheres or spherical caps whose respective centers substantially coincide in an end-of-travel position of the press, so that the radial distance ( E) between the two opposite front walls (15a, 16a; 15th, 16th) is substantially the same over the entire extent of these walls in said position.

3. Press according to claim 1, characterized in that said convex and concave shapes correspond so that the axial distance (A) between the two opposite front walls (15b, 16b) is substantially the same over the entire extent of these walls.

REPLACEMENT SHEET

4. Press according to claim 1 or 3, characterized in that said general shape of the front walls comprises a central portion of planar surface (43, 44), surrounded by a portion of non-planar surface (41, 42).

5. Press according to one of the preceding claims, characterized in that at least one of the filter elements (23, 24) has surface undulations on a surface portion with a convex, concave or planar shape.

6. Press according to one of the preceding claims, characterized in that a cylindrical peripheral wall (10) of each pressing chamber (1) comprises at least one filter element (32) and conduits (33, 34) of evacuation of liquid on the back of this filter element.

7. Press according to one of the preceding claims, characterized in that said filter elements (23, 24, 32) comprise porous plates of sintered metal.

8. Press according to one of the preceding claims, characterized in that at least one of the filter elements (23, 24) of the front walls is made of a single porous plate of sintered metal.

REPLACEMENT SHEET