FR2584653A1 - Press for squeezing slices of sugar beet - Google Patents

Abstract

The sugar beet press has a turning plate (10) with a drive (11) that lifts and lowers it in an annular press chassis between an upper part (1) and a lower part (2) of the press. These parts can be moved together by a hydraulic closure drive (4,5). The plate takes at least one annular filtering strip layer (7) and a lining device places successive layers of the product to be pressed on the filter strip. The upper part of the press has a notch (3) and the lining device and a discharge device (9) are placed in the notch zone.

Description

Press for pressing plant elements
The present invention relates to presses for pressing plant elements, in particular for the secondary compression of beet pulps.

 In the manufacture of sugar from beet chips, the beet pulps which leave the extraction tower are then presented as a by-product.

 The extracted pulps are compressed in worm presses and the juice expressed is sent back to the production of sugar.

 Compressed pulps have a dry matter content of 18 to 24%.

 Some of these pulps are sent to agriculture under the name of "pressed pulps" to serve as silage pulps for livestock feed.

 These relatively high moisture load pulps are not stable. They ferment and mold, creating a very strong pollution nuisance due to the odor. This is why these pulps are dried by adding thermal energy to bring them to a dry matter content of 90%.

 The drying operation is carried out using rotary ovens, with combustion gas supply or auxiliary supply, generally with heavy oils. In general, this molasses drying operation is also introduced into this operation, which, during evaporation, causes a nuisance due to the odor which is conventional in the sugar industry, but which is no longer tolerable with the prescriptions. environmental issues. This also requires additional filters and condensing systems, which entail considerable investment costs.

 In addition to attempts to use beet pulps for the production of digestion gas, or bio-gas by pyrolysis, we have also developed other methods of seggeafindere'alising economical miessurles raised ~ energy engaged in lteration of Among other things, so-called low temperature dryers have been developed in order to be able to use for the pulp drying the residual energy which, moreover, can no longer be used in the manufacture of sugar. The pulps are piled up in layers on air-permeable sieve strips which then extend over several stages. The pulps are then traversed by hot air which, from large fans, is brought to installation through large heat exchangers. With these installations, the beet pulps are dried with a dry matter content going from 18 to 24% to about 30 to 45%. These installations have very large dimensions.

These are generally buildings about 15 m high, 10 m wide and 30-40 m long. The investment costs necessary for this are very high and the energy consumption for the hot air fans is also not insignificant. Apart from the fact that one can also use the calorific energy thus required, for other needs, such as heating, industrial water or reserve energy, hot air fans require electrical energy of several thousand kW. Since sugar factories generally produce their own electrical energy, the installed capacity is often not sufficient and other investment costs are incurred or else the electrical energy must be brought from outside.

 In addition to attempts to extract further juice from beet pulps using screw presses, tests have been developed to increase the dry matter content of the pulps by static pressure extraction.

 In this case, it turns out that it is possible, by extracting the juice, to reduce the pulps to approximately 45 to 50% of dry matter content if they are distributed in thin layers on filtration fabrics, if these layers and if they are then subjected to a high compression pressure of approximately 50 bars.

 We then built test facilities in which we wrap a filtration band on a cylinder such as a reel, we unroll this filtration band from the cylinder or reel and we rewind it on another reel, then filling uniformly this beet pulp filtration band.

 The filled reel is then introduced into a tank, the internal wall of which is provided with a compression membrane. This compression membrane is then subjected to the action of a pressure agent, most of the time water, and the pulps are then subjected to another extraction of juice.

 In this pressing or pressing process, the reel is removed from the tank and rewound on the other reel, the pressed pulps being separated by scraping.

 The loading and unloading of the pulps is largely automated, but the automatic introduction and extraction of the reel in the tanks have not been resolved to date.

 As a result, during the extraction of juice in the tank, the dispenser is compressed with an outer diameter wound to a smaller diameter, the membrane is subjected to considerable expansion. In addition, the filtration bands are compressed from a large diameter to a smaller diameter.

In order to keep the expansions of the membranes, as well as the deformations of the filter fabrics, within admissible limits, the capacity of these installations is very limited, so that even for an average sugar factory, several of these machines are needed to reach the capacities. required. In addition to the considerable investment costs, there is also a need for significant installation space in this case, which in many cases is not available.

 This is why the invention aims to provide a large capacity press working according to this principle technical process.

 To this end, the subject of the invention is a press for pressing plant elements, in particular for the secondary compression of beet pulps, characterized in that a rotary table is placed in an essentially annular press frame, between a part upper press and lower press part which can be tightened against each other by means of a preferably hydraulic closing device, this turntable can be raised and lowered and can be fitted with a filtration band in at least one layer, while a loading device is provided for depositing the material to be pressed in layers on this filtration band. The advantages of this arrangement, as well as details of execution will emerge from the description which follows.

 This secondary compression installation comprises a press frame with an annular cross section.

 The lower press part is connected to the upper part by a variable stroke closing mechanism. This closing mechanism can be mechanical, but preferably hydraulic. To produce the necessary high compression pressure, a multiplicity of hydraulic cylinders is required. Another pos sibility consists in realizing the entire annular surface as a closing cylinder, in which case the machine is not only of considerably larger dimensions, but also heavier.

 The embodiment described below relates to a press with an oleohydraulic closing mechanism. A turntable is carried by the lower press frame. The underside of this table is arranged so that it rests on this lower press part by the whole of its annular surface. The upper face of this table advantageously has a profile allowing the evacuation of liquids. A simple embodiment consists in putting in place a stable mesh with tight meshes, the metal wires having a thickness of approximately 2 to 3 mm, and to place over simple perforated sheets which are then screwed at the same time as the mesh on the table using countersunk head screws, so that a smooth surface is obtained.

 This turntable is centered and guided on its external contour and its internal contour using horizontal rollers. In the vertical plane, this table is advantageously carried, on its outside diameter, by rollers which are displaceable in height - preferably using a hydraulic device -, so that this table of its support on the lower part of the press. This turntable can be driven, outside or inside, using toothed rings or a friction roller.

 The annular press frame is interrupted over an angular range of approximately 45 to 60 ". This recess can also exist in the lower press part, but in both cases it must however be provided in the part press superior.

 It is in this recess that the loading and unloading device is placed.

 The whole of this loading and unloading device consists of a winding drum for the filter cloth, a drive device for this filter cloth and a device ensuring the regulation of the progress of this filter cloth and loading and unloading device.

 The filter cloth forms annular layers which rest on each other. This filter fabric can be woven in an annular form or be assembled from annular segments, by sewing, welding or gluing, and this in several layers. Several of these layers are again linked together by removable links, such as zippers or crocodile links, in the form of a multiplicity of layers which then rest on one another in the form of spirals.

 The number of annular filter cloths resting on each other is determined according to the size of the installation and can be between 20 and 100.

 This filter fabric is then wound on a conical drum having an elongated cylindrical end, on the narrow end of the cone and so that each layer of this filter fabric is, depending on the thickness of the fabric and the conicity of the drum, offset along the longitudinal direction of this drum so that the outside diameter of the latter or of the winding remains constant both for the large diameter of the cone and also for its small diameter.

 In the unloaded state, this filter cloth is on the reel drum with the exception of the fixing end which is made integral with the rotary table. The take-up drum is moved along its longitudinal axis so that it projects out of the annular surface of the press frame.

 The secondary pressing or compression installation is shown in the accompanying drawings.

 Figure 1 shows the annular press frame, seen from above, with the upper press part 1, the recess 3, the internal closing cylinders 4, the external closing cylinders 5 and the take-up drum 6 load using filter cloth.

 FIG. 2 represents the installation of the figure seen from the front, and one can see there the upper part of press 1, the lower frame of press 2, the filter band 7, the filter band drive 8, the unloading device 9, the rotary table 10 and the device 11 for lifting the rotary table, as well as the pressure roller 12 and the press feet 13.

 The rotary table 10 and the belt drive 8 of the drum 6 are coupled to each other without sliding.

 FIG. 3 shows the same view as FIG. 2, but with the machine loaded with beet pulp, with the superimposed layers 14 and the loading device 15, as well as the tape regulation roller 16.

 FIG. 4 represents FIG. 3 seen from above, with the take-up drum 6 unwound and tucked into the recess 3. One can see there the cylindrical end 17 of this take-up drum 6 from which the filter cloth has been unwound.

FIG. 5 represents the machine in section, the machine being shown open on the left with the upper press part 1 and the lower press part 2, the rotary table 10, with a flow gutter 18 for the press filtrate, and inside
the toothed crown 19 used for the drive. We can see the support surface 20 by which the rotary table rests on the lower press part 2 in order to absorb the compression forces. This turntable has a V-shaped profile with an inclination of about 150, the interior surface inclined outward being substantially the same size as the exterior surface inclined inward.

 The rotary table 10 and the associated surfaces of the upper part and the lower press part may have, in vertical section, a roof-shaped or zigzag-shaped profile.

 On the one hand, it is of very particular importance, for the secondary pressing of the pulps, to exert on them a shearing force which has a considerable influence for the secondary pressing effect, that is to say ie for the dry matter content that can be obtained. On the other hand, due to the inclined surfaces, no free radial force should appear which could deform the upper and lower parts of the press since the closed annular shape is interrupted by the recess 3.

 The inclination of these surfaces has another advantage in that the press filtrate adopts a single flow direction and can be evacuated at the lowest point of the table, by the gutter 18 and the flow pipes 21 which are evenly distributed around the periphery.

 The threaded nuts 22 of the inner cylinders and 23 of the outer cylinders are provided with a flange and are held on the lower part of the press by means of rings 24 and 25, so that there is no need to remove these nuts during a possible disassembly of the cylinders with a view to replacing the seals. We can also see the exterior and interior tie rods 33 and 34.

 The press is shown in the closed state on the right side of FIG. 5, with the drive 26 of the rotary table which in this embodiment is obtained by means of the gear 2i from 'a hydraulic motor 26'. The bevel gear 29 is driven from the bevel gear 27, preferably by means of an articulated shaft 28. In this bevel gear 29 is fitted a shaft 30 which is moved in this gear 29 during the lift stroke of the upper press section.

In order to avoid alignment errors, the drive passes, from this shaft 30, and by means of a double gimbal 31, on a bevel gear 32 and, from there, on the drive unit. drive 8. It is thus ensured that the rotary table moves in synchronism with the drive of the filtration band.

 Figure 6 shows Figure 5 seen from above. We see represented on the right the upper part of press 1, and on the left, in section, the lower part of press 2. This upper part and this lower part are here represented, both as in the form of foundry segments which are screwed together on the mounting location. This is advantageous for large machines, both in manufacturing and also in transport. We can still see there the drive 26 of the rotary table, with the articulated shaft 28 and the bevel gear 29. We also see there the lifting unit 11 off-center of the rotary table, four units being arranged with an offset of 900 each time with respect to each other.

 FIG. 7 represents a section of the lower part 2, with the rotary table 10, the device 11 for lifting and guiding this table and the winding drum 6 placed in the recess 3 and having its cylindrical end 17.

 The turntable has a drainage covering 35 which can be formed by grooves provided in this table or by the interposition of a grid provided with a perforated sheet coating.

 The winding drum 6 is mounted on a carrying frame 39 movably along its longitudinal axis, this drum being received on the right in a collar bearing 36 and on the left in a guide plate 37 provided with rollers 38 which guide the drum by its cylindrical end 17.

 The collar bearing 36 is mounted on two guide columns 40 provided with guide sleeves 41. Ball bearing assemblies are preferably arranged in these winding manthons, but without being shown in a visible manner.

 The movement of the winding drum is obtained by means of the threaded rod 42 which can also be produced in the form of a threaded rod with balls. At each turn of the drum, it moves on the threaded rod of the amount of the thread pitch. A correction of the position of this drum can be obtained by rotating the threaded rod, the latter being moved in rotation by the drive 43 which is preferably produced in the form of a hydraulic motor.

 A roller 44 free in rotation, or compensating roller is disposed on the winding drum, this roller being guided on both sides in closed bearings 45 and 46 and being able to be moved in height using bolts 47 and 48. This roller compensator is moved in rotation due to contact with the take-up drum or with the filter cloth on this drum. It is possible to provide, between the closed bearings and the guide bolts, springs with the aid of which the support pressure of this compensating roller can be adjusted on the drum.

 FIG. 8 represents a part of the press frame seen from the front, without the take-up drum. You can see the bevel drive gear 27 with the drive motor 26 'and the articulated shaft 28, the bevel gear 29 and the gear system 32 provided for the drive drum 8. At this drive drum S is associated with a clamping roller 50 which can be clamped on this drum using angled levers 51 and 52, compression springs 53 and 54 and adjusting screws 55 and 56. The filter cloth 7 is guided between this drive drum and this clamping roller, then is then guided in the press frame by passing over a console 57 of the loading device 15 and over the pressure roller 12.

 The unloading device 9 is preferably a curved scraper which can be lifted from the filtration band using small adjustment jacks 58.

 The scraper extends at an angle at an angle to a radius of the turntable 10.

 Figure 9 shows the same part as Figure 8, but -------- -with the winding drum in place, this drum being here represented with the filtration band 7 placed on it. From this drum, the filtration band 7 passes over the regulating roller 16, on the clamping roller 50 and the drive roller 8, bearing on the console 57, below the unloading device 9 , the loading device 15 and the pressure roller 12, then into the press frame.

 The regulating roller is controlled using a firm bearing 59 and an adjustment cylinder 60.

 The pressure roller 12 is driven, for a synchronous rotational movement, from the gear 32 and by means of an articulated shaft 61 and a bevel gear 62.

 We can see on the winding drum 6 the drive 63 provided for this drum and which is preferably a hydraulic motor, this drive attacking the drum by means of a pair of toothed wheels and maintaining it under a prior tension.

 FIG. 10 shows the flange 37 with its rollers 38 in which the cylindrical end 17 of the take-up drum is guided. We can also see a journal bearing 64 in which the regulating roller 16 is received in a tilting manner by its lower axial end.

 Figure 11 shows the part of Figure 8 seen from above.

Figure 12 shows a side view of the pressure roller 12 and
FIG. 13 the end view of this roller 12.

 It can be seen in these figures 12 and 13 that this pressure roller 12 can be displaced parallel in height using parallel levers 65 and 66 located on both sides and using interlocking pins 67 and 68, in cooperation with a flange 69.

 FIG. 14 represents a side view of the loading device 15.

 FIG. 15 represents the end view of this positive loading device.

 This device has, in the direction of supply of the pulps, a shutter 70 which can be opened and closed using bent levers 71 and 72 and small adjustment cylinders 73 and 74.

 This device also has side flaps 75 and 76 which can also be opened and closed using small lifting cylinders 77 and 78.

 FIG. 16 represents the winding drum 6 with its collar bearing 36 and its drive motor 63 and the pair as associated with toothed wheels 79 and 80.

 FIG. 17 represents the entrainment 43 provided for the threaded rod 42.

 FIG. 18 shows the lifting and guiding device 11 provided for the rotary table 10. A rolling roller 81 is disposed below the outer rolling crown of this table, with also, for each unit 11, two rollers guide 82 which are externally supported on this rolling crown.

 The whole rolling unit is radially adjustable relative to the rotary table, thanks to a guide pin 83 and - - an eccentric bush 84. The whole unit is movable in height at using a hydraulic lifting cylinder 85.

Figure 19 shows Figure 18 in top view and
Figure 20: this figure 18 in front view.

 Figure 21 shows the hydraulic diagram of the entire installation.

The operation of this installation is carried out in the following manner
At the beginning, the press is empty. The filter cloth - insofar as it cannot be woven in an annular form - is cut in the form of circular segments which are sewn or welded together. Several of these annular units placed one above the other are interconnected by zippers or interlocking links. This has the advantage that, in the event of local damage to the filter fabric, it is possible to extract or exchange only determined sections of this fabric.

 One end of this multi-layer annular structure 7 is fixed to the rotary table 10, and its other end to the take-up drum 6. The dimensions of this drum 6, as regards its small diameter and its large diameter, as well as its length corresponds to the proportions of the turntable with regard to its inside and outside diameters, as well as its width. All the other tapered rollers also correspond to these proportions.

 At first, the press was largely closed. The upper press part 1 is only 100 to 200 mm above the lower part 2. The filter cloth is, depending on the unwindBentg, in a number of layers over the take-up drum. Each layer of the filter cloth is offset in the axial direction on this drum in the manner of a thread pitch. The pitch of these layers offset in the axial direction corresponds on the one hand to the conicity of the drum and on the other hand to the thickness of this filter fabric. Each layer has the same large diameter, the same small diameter and the same conicity, so that each layer has the same unrolled length. The take-up drum is moved along its longitudinal axis so that the upper layer, which is at the same time the outermost, is always at the same distance from the axis of rotation of the rotary table, which means that the drum 6 fully furnished is offset towards the outside, out of the press frame, as shown in FIG. 1.

 From this winding drum 6, the filtration band 7 is guided over the regulating roller 16, and over the clamping roller 8, the filtration band winding first on the clamping roller 50 over an angle of approximately 1800, then also winding over 1800 on the drive roller 8, to finally be applied on the console 57. This filtration band is then introduced below the unloading device 9 raised and at below the loading device 15, as well as the pressure roller 12, as far as the press frame, while being fixed directly on the rotary table.

 All the axes of the rollers 6, 16, 50 and 8 and of the compensating roller 44 point to a common central point located in the area of the vertical axis of the press frame.

 For loading, the pressed pulps are brought by a conveyor belt of the loading device 15, not shown.

Advantageously, this conveyor belt is loaded using a filling hopper so that, in the area of the inside diameter of the press frame, the layer height is lower than at the location of the outside diameter. The increase in layer thickness must be linear, and this so that theoretically the base line of the belt conveyor intersects the line of layer height on the central axis of the press. The belt conveyor drive is thus coupled to the machine control which, if necessary, can be switched on and off.

 Thanks to the commissioning of the turntable, we are assured of synchronous operation with the drive unit 8, by means of the mechanical gears 27, 29 and 32.

 The turntable is then raised using the four lifting devices 11 and is guided using the rollers 81 and 82. The winding drum 6 is subjected to a prior tension using the hydraulic motor of drive 63, so that the filtration band 7 is at all times held taut between this drum 6 and the drive 8. As the turntable moves, this filtration band is unwound from the take-up drum thanks to the drive 8. To do this, the take-up drum rotates around the threaded rod 42 which is. first of all stationary, this drum therefore moving along its axis in the direction of the vertical axis of the press frame. The pitch of the threaded rod must then correspond substantially to the pitch of the layers of filtration band located on the drum.

In the case of different thicknesses of the filter fabric as well as remnants of the filling of this filter fabric, or even under other influences, the pitch variations can be compensated by adjusting the threaded rod 42 using the hydraulic motor 43 The contact or the order to command is then obtained using the roller 44 which is free to rotate.

 The purpose of this compensating roller 44 is first of all to prevent the layers of filter fabric from sliding on the take-up drum which is inclined inwards. However, this risk only arises in the case of very smooth filter fabrics.

If, moreover, during the unwinding of the filtration band from the reel drum, the pitch of the threaded rod is greater than the thickness of the filter cloth, the drum moves too quickly towards the central axis of the frame. press and compensating roller is raised on its bearings 45 and 46 Thanks to the modification of the stroke of the guide bolts 47 and 48, it is then possible to put into service commercial contact devices - not shown in the drawings - intended for the motor hydraulic 43, and thus retract the threaded rod until the guide bolts 47 and 48, and therefore the compensating roller, are again in the normal position. If the threaded rod is too weak, the installation works in the opposite direction. Thanks to this control installation, the filter band is wound and always unwound at constant distance from the vertical axis of the press frame. The filtration band then runs from the reel drum into the drive 8, passing over the regulating roller 16. This roller 16 is tiltably received by its thin end on the flange 37, at the level of the articulation 64. The front bearing 56 of this regulating roller 16 is adjustable using the regulating cylinder 60 with regard to its distance from the axis of the take-up drum
Advantageously, the outer edge of the filtration band 7 is detected using a feeler, a photoelectric barrier or another commercial detection device. In the event of a change in the position of the filter cloth, the axial position of the roller 16 is offset by adjusting the actuator 60, so that the filtration band is returned to the normal position. Thanks to this arrangement, it is ensured that the filtration band is always applied in the suitable position on the turntable using the drive and using the loading device or is always applied in the position suitable on the take-up drum during unloading.

 The loading device 15 has, transversely to the filtration band, a shutter shutter adjustable in height 70 with the aid of which the layer height of the beet pulp which is present on this filtration band can be adjusted. This shutter can be closed using the small control cylinders 73 and 74.

 This loading device also has laterally, on the outside and on the inside, adjustable cheeks 75 and 76 which can also be raised and lowered using small adjustment cylinders 77 and 78. During loading, these side cheeks went down.

 The beet pulp falls from the belt conveyor into this loading device 15 and can, via the regulated slot of the shutter 70 and when the filtration band slides over the console 57, spread out according to the planned height of the layers on this filtration band.

 The packing of this filtration band must only be carried out in the area of the compression surfaces, that is to say outside the area of the recess 3. Normally, this recess represents 40 "to 600 of the 360 "ring. The area of this recess 3 is determined on the periphery of the rotary table 10 using adjustable stops which are fixed in the groove 86. The control is carried out using non-contact limit switches, so that the shutter 70 is lowered and thus the lining is prevented. It is also advantageous here to immobilize the belt conveyor in order to prevent overfilling of the loading device. Once the angle thus adjusted is exceeded, the shutter is opened again.

 The filtration band 7, which rests on the console 57, is located simultaneously, before it is introduced into the press frame, driven by the pressure roller 12, given that the latter is also driven synchronously by means of the articulated shaft 61 and the bevel gear 62. This pressure roller 12 is arranged so that it can be displaced in height parallel to itself. The height of the clamping pressure of this pressure roller can be adjusted by means of a lever linkage, not shown, comprising loading or unloading springs. In the non-lined state, the pressure roller rests directly on the filter band and, since the surface of this roller is coated with flexible rubber, the friction between the roller and the filter cloth is greater than that between this filter cloth and the bearing surface 57 of the console. As a result, this filtration band is also kept taut in the unpacked state. When the filter cloth is filled, the filling layer is trapped by the compression force of the roller and is also driven by this roller. In addition, the filter cloth acts itself by its support on the turntable, as well as the weight of the packed filter cloth located between the roller and the table covering, to give a tensile force applied to the entire filtration band.

 The filter cloth is then filled with beet pulp on each layer and over an angular range of 300 to 3150 - depending on the setting - so that, when applied on the turntable, this filter cloth adapts to the V-shaped profile of this table.

It may then be advantageous not to fill this filter fabric over a width of 5 to 10 cm at the point of the deepest point of the V-shaped profile, in order to ensure a smoother flow of the pressure filtrate. For this purpose, a deflector is provided ------ in the loading hopper of the device 15 so that there can be no lining at this location. This deflector --- can be obtained at using an incorporated roof-shaped bar
When the number of layers of the lining increases, there is an indication of contact on the hydraulic system of the press by means of a device (not shown) for measuring, which may be both of the mechanical type, with a roller, and also of the type without contact with a photocell, ultrasound, infrared or radioactive means, so that the upper part of the press can be lifted until the measuring device is again free and the hydraulic system again put out of service.

 Thus, the packing of the press is carried out in a continuous manner, with a step-by-step raising of the upper part of the press. Since all the devices are fixed to this upper part in the region of the recess 3, these elements of the installation are simultaneously raised.

 The end of loading state is monitored both via the total loading height and also via a counting system, or even the extreme axial position of the take-up drum.

 After loading, the press table is first lowered, the pressure being cut off on the hydraulic lifting system 85 provided in the lifting devices 11. It is then that the pressing operation begins.

 The press is quickly closed by means of an oil accumulator pressurized beforehand using compressed air and / or using a low pressure circuit, so that the deposited volume of pressed pulp is very quickly reduced to about 25% of the original volume. Thanks to suitable pressure levels, the hydraulic closing system is then switched to high pressure and is subjected to the action of hydraulic pressure which corresponds to about 50 bars for the pressure surface of the pulps.

 The pressure filtrate flows in transverse filtration along the filtration fabric, up to the lowest point of the V-shaped packing profile, or also outwards and inwards on the edges of the fabric, up to the grooved surface of the turntable. At this point, the filtrate is brought, by drainage, to the V-shaped recess provided in the turntable and through the filtrate chute 18 and the filtrate drain pipes 21 to a tube. common collector. The time of application of the compression under high pressure can be determined - in accordance with the results of the tests - by chronological fixation, but also also by means of the measurement of the momentary quantity of flow of the pressure filtrate.

 Once the pressing operation is complete, the press is switched to the opening, a slow release of pressure occurring first. The press is then opened via the pressure accumulator and / or the low-pressure circuit, until the height measuring device, which is preferably a photocell, is again released. .

 The turntable is then raised using the lifting cylinders 85 and it is also the same for the shutter 70 using the hydraulic cylinders 73 and 74 and the side cheeks 75 and 76 using hydraulic cylinders 77 and 78. This raising of the lateral cheeks is made necessary by the fact that the pressed pulps move outwards and inwards under the effect of the compression pressure and that these pressed pulps occupy on the filtration band greater filling width than freshly loaded pulp.

 The unloading scraper 9 is then lowered using the hydraulic cylinder 58 and the drive 26 ′ of the rotary table as well as the prior tensioning drive 63 of the take-up drum 6 are put into service. The drive 8 of the filtration band and the pressure roller 12 are also put into service from the rotary table 10, by means of the mechanical connection. The filter band is then extracted from the press frame and wound on the take-up drum 6. The pressed pulps, which are nested one inside the other like potato rings in the gratins, are then ejected outwards Using the unloading device 9. This unloading scraper has an inclined position towards the outside and towards the bottom and advantageously offers a hollow shape, the extraction of the pressed-out pulps being thus thus favored. Furthermore, the centripetal force resulting from the displacement of the turntable also acts favorably on the extraction of the pulps.

 The control of the filtration band and the drum reel has been sufficiently described for the loading operation and it is simply carried out in reverse for unloading.

 For this unloading, the press is switched to closing and, when the photocell for height measurement is released, the upper part of the press is then lowered until, due to the masking ---- of this cell photoelectric, the hydraulic closing system is again put out of service. Thus, during unloading, the upper press part is gradually brought back to the filling state.

 The unloading state is, as already indicated, monitored using the number of layers and the extreme position of the upper part of the press, as well as the take-up drum, and the press is then ready for new loading operation.

 When loading the press, the turntable is rotated in the direction of arrow 91 (fig.

3), so that a layer of press material of predetermined thickness is deposited, by the loading device 15, on the surface facing upwards of the filtration band 7 coming from the drum 6, this layer of material is found to be subject to light compaction - preliminary using the pressure roller 12.

 Once the pressed materials which are one above the other in several layers over the strip of filter cloth have been pressed using the closing device constituted by the jacks 4 and 5, the compression pressure is reduced, as previously indicated, and the upper press part is subsequently slightly raised. To empty the press, the rotary table 10 is then rotated in the opposite direction (arrow 90 in FIG. 9), so that, thanks to the scraper 9, the combined layer of pressed material is separated by scraping from the filter band 7 returning to wind on the drum 6 and is discharged to the outside.

 As an alternative to the embodiment shown and described, the lower press frame 2 and the rotary table 10 are advantageously produced in the form of firm rings, so that only the upper press part 1 has a suitable recess 3 in the drum area 6. This therefore results in better transmission of forces during the pressing operation and greater rigidity of the entire structure.

Claims (36)

 1.Press for pressing plant elements, in particular for the secondary compression of beet pulps, characterized in that a rotary table (10) is arranged in an essentially annular press frame, between an upper press part (1) and a lower press part (2) which can be clamped one against the other by means of a closing device (4, 5) preferably hydraulic, -this rotary table (10) which can be raised and lowered and capable of being fitted with a filtration band (7) in at least one layer, while a loading device (15) is provided for depositing the material to be pressed in layers on this filtration band (7).  2. Press according to claim 1, characterized in that there is provided, at least in the annular upper part of the press (1), a recess (3) in the area of which the loading device (15) is arranged and a unloading device (9).  3. Press according to claim 1 or 2, - ---- characterized in that the filtration band (7) is produced in annular form.  4. Press according to any one of claims 1 to 3, characterized in that, with a view to placing the pressed material in several layers, the filtration band (7) is composed of several annular segments, the individual annular segments being connected to each other, partially removably and partially permanently, so as to constitute a continuous band.  5. Press according to any one of claims 1 to 4, characterized in that the permanent connections are advantageously made by welding, sewing or gluing and the removable connections are constituted by slide fasteners or interlocking connections.  6. Press according to any one of claims 1 to 5, characterized in that a conical drum (6) intended for the filtration band (7) is disposed on the press frame, the end of this drum having the smallest diameter being directed towards the axis of rotation of the rotary table (10).  7. Press according to any one of claims 1 to 6, characterized in that the conical drum (6) is arranged in the region of the recess (3).  8. Press according to claim 6 ---------- or 7, characterized in that the conical drum (6) has on the side of its small diameter a cylindrical end (17).  9. Press according to any one of claims 1 to 8, characterized in that the drum (6) is mounted movable along its longitudinal axis.  10. Press according to any one of claims 1 to 9, characterized in that the longitudinal displacement is carried out using a stationary threaded rod (42) and a threaded nut connected to the drum (6).  11. Press according to claim 10, characterized in that the threaded rod (42) is further fixed to the press frame in an axially adjustable manner.  12. Press according to any one of claims 1 to 11, characterized in that the drum) is connected to a belt drive (8) which is arranged so that the filtration band (7) being on the drum ( 6) is maintained under a prior tension in the two directions of rotation, under an adjustable tensile force.  13. Press according to any one of claims 1 to 12, characterized in that the rotary table (10) and the belt drive (8) of the drum (6) are coupled to each other without sliding and in that the rotary table (10) is connected to a drive motor (26 ').  14. Press according to claim 13, characterized in that the drive motor (26 ') is constituted by a hydraulic motor.  15. Press according to any one of claims 1 to 14, characterized in that it is associated with the drum (6) a compensating roller (44) on which the filtration band (7) is guided and which prevents this ~ band filtration slide from the drum (6).  16. Press according to claim 15, characterized in that the compensating roller (44) is connected to a device for determining the position of the drum (6) relative to the press frame.  17. Press according to any one of claims 1 to 16, characterized in that there is provided between the drum (6) and the belt drive (8) a belt regulation device (16).  18. Press according to any one of claims 1 to 17, characterized in that the loading device (15) is disposed between the belt drive (8) and the turntable (10).  19. Press according to claim 18, characterized in that the loading device (15) is provided in the loading direction with a shutter (70).  20. Press according to claim 19, characterized in that the shutter (70) can, if necessary, be opened and closed with the aid of an adjustment drive.  21. Press according to any one of claims 1 to 20, characterized in that the loading device (15) is provided on both sides with adjustable cheeks (75, 76) for adjusting the width of the layer of material pressed onto the filter cloth.  22. Press according to any one of claims 1 to 21, characterized in that a pressure roller (12) applying pressure on the layer of pressed material is disposed between the loading device (15) and the turntable (10).  23. Press according to claim 22, characterized in that the pressure roller (12) is driven in synchronism with the rotary table (10) and the belt drive (8).  24. Press according to claim 22 or 23, characterized in that the pressure roller (12) is mounted on the press frame by being movable and adjustable parallel to itself in height.  25. Press according to any one of claims 22 to 24, characterized in that the pressure roller (12) is connected to a device for varying and / or adjusting the compression pressure.  26. Press according to any one of claims 1 to 25, characterized in that an extraction device or unloading device (9) for the press material having undergone the pressure is arranged above the filtration band ( 7) in the area between the pressure roller (12) and the belt drive (8).  27. Press according to claim 26, characterized in that the unloading device (9) is constituted by a scraper and in that this scraper is mounted on the press frame so as to be able to be pressed on the filtration band (7 ) and be relieved of it.  28. Press according to claim 26 or 27, characterized in that the scraper extends in an inclined manner at an angle with respect to a radius of the rotary table (10).  29. Press according to any one of claims 26 to 28, characterized in that the inclination of the scraper with respect to the radius extends "in advance" in the direction of rotation of the rotary table during extraction. (arrow 90).  30. Press according to any one of claims 1 to 29, characterized in that the rotary table (10) and the associated surfaces of the upper press part (1) and the lower press part (2) have in section vertical a flat profile.  31. Press according to any one of claims 1 to 29, characterized in that the rotary table (10) and the associated surfaces of the upper press part (1) and the lower press part (2) have in vertical section an inclined profile.  32. Press according to any one of claims 1 to 29, characterized in that the rotary table (10) and the associated surfaces of the upper press part (1) and the lower press part (2) have in section vertical profile shaped V.  33. Press according to any one of claims 1 to 29, characterized in that the rotary table (10) and the associated surfaces of the upper press part (1) and the lower press part (2) have in section vertical a roof-shaped profile.  34. Press according to any one of claims 1 to 29, characterized in that the rotary table (10) and the associated surfaces of the upper press part (1) and the lower press part (2) have in section vertical a zigzag-shaped profile.  35. Press according to any one of claims 1 to 34, characterized in that the angle of inclination of the surfaces associated with each other is equal and in that the inclined surfaces are of the same size.  36. Press according to any one of claims 1 to 35, characterized in that the vector sum of the forces coming from the product of the vertical projection of the surfaces and the tangent of their angle of inclination is of the same magnitude.