BRIQUETTING APPARATUS

Abstract: A briquetting apparatus, primarily for straw or similar materials, has a first pre-chamber (2) into which the material is fed, a first ram (3) compressing the material in the pre-chamber into a second pre-chamber (9). A second ram (8) compresses the material in the second pre-chamber directly into a main compressing chamber (11) in which the material is compressed by a main ram (14) and from which it is forced through an extended opening (16) at the end of the compressing chamber.

Description: PROTETTING APPΛPATyg The present invention relates to briquetting apparatus for compaction and extrusion of primarily fibrous or , other organic materials such as straw, hay, wood shavings etc., but also granular materials such as coal dust, rice husks etc. Such machines are being used increasingly for bulk reduction and in order to reduce wastage of material; in the case of straw, by enabling compaction of the straw into briquettes for subsequent use as a fuel in firing boilers or other co bustors, as animal feed and bedding. Compacting such materials increases the density to a suitable level for use as a burning fuel and at the same time reduces the transportation problems associated with the undensified material. Various machines have been proposed in the past, a number of them incorporating an elongate cylinder in which a piston reciprocates and into which loose material is fed to be compacted by the reciprocating action of the piston in the cylinder, the cylinder having or comprising a slightly tapering extrusion die in order to enable a build-up of pressure in the material to be compacted. Other machines have auger-like devices which force loose material into a plurality of dies under pressure in order to compact it. However, machines of these types require large power inputs if they are to produce usable material at a reasonable rate and are usually large and cumbersome, making them transportable only with difficulty. From SE-B-8303337 a briquetting machine is known which comprises a compressing chamber first and second rams movable in directions transverse to one another to partially compress the material; and a third ram movable in the compressing chamber in a third direction transverse to the first and second directions to further compress the material and force it through an extended opening at the end of the compressing chamber. In this machine the compressing chamber is located at the bottom of a hopper into which the fibrous material is loaded and which falls under gravity into the compressing chamber. To provide additional compaction the first ram very slightly compresses the material sideways into the compressing chamber and then the second ram, moving in the hopper, moves downwards to the top of the compressing chamber to further compact the material before final compaction by the third ram. The total pre-compaction ratio is thus relatively small, and, as stated in the specification, this leads to relatively small output levels. To overcome these and other problems a briquetting apparatus according to the present invention is characterized in that the material is fed to a first pre-chamber separate and offset, in the directions of both the first and second rams, from the main chamber, the first ram moving through the first pre-chamber to compress material into a second pre-chamber disposed immediately adjacent the compressing chamber, and the second ram moving through the second pre-chamber to compress material into the compressing chamber. By separating the first pre-chamber completely from the compressing chamber the swept volume of the first pre-chamber can be increased such as to allow high compaction ratios during the two pre-compaction stages, and also enable a range of first pre-chamber constructions and sizes to be used as alternatives, thus allowing modification of the construction on a modular basis as required to suit different materials. By arranging for compaction/densification to take place in three stages, in three chambers, each in a different direction, a regulated amount of material can be fed in a positive manner to fill the main chamber consistently, thus giving substantially equal lengths of briquettes as a finished product at the same time ensuring that a high degree of compaction can be achieved without requiring massive components and hence the high power requirements associated with many conventional machines. Preferably, the three axes are orthogonal and each of the rams is movable by hydraulic pressure to cause compression. The third ram may comprise one end of a double-acting ram moving in alternate directions to compress material in a pair of main chambers, one at each end, thereby avoiding the need for a "wasted" return stroke, and increasing the throughput of the apparatus. Preferably, a feed device feeds material from a hopper which discharges vertically under gravity into the first pre-chamber, the first ram moving horizontally in the first pre-chamber to compress the material at one end of the pre-chamber, the second ram being movable vertically through a second pre-chamber at the end of the first pre-chamber to move the material downwards into the main chamber disposed horizontally and through which the third ram is movable. Preferably, the or each main chamber extends into an extrusion cylinder formed, at least over part of its length, by a pair of substantially semi-cylindrical shells movable under hydraulic pressure towards one another to provide sufficient frictional resistance to enable final compaction to take place in the main chamber prior to extrusion through the end of the extrusion cylinder. The pressure of material within the extrusion cylinder can be controlled by varying the distance apart of the two shells, this in turn being carried out by hydraulic pressure in conjunction with the hydraulic pressure feed to the main cylinder and ram. Advantageously, the swept volumes of the pre-chambers may be arranged to be changeable to adjust the compaction ratios to suit different materials, by varying the strokes of the respective rams and/or one or more of the cross-sectional dimensions. Preferably, each of the first and second rams has a closure plate movable with it and positioned so as to close its respective chamber behind the operating face of the ram when the ram is extended, to allow the next charge of material to be prepared by the feed device or first ram respectively in advance of the return of the first ram and second ram respectively. The invention also includes a method of manufacturing briquettes using apparatus as described above. In such a process, when the raw material to be compressed is straw, the straw is cut to a larger length than the conventional length, being chopped by passage through a 15 to 18 mm screen. It has been found that this may enable the fibres of straw to be interlocked during the compaction process avoiding the need for additive binders and the like which are frequently used in prior art methods and also avoiding the need for the briquettes to be densified to the same extent in order to hold together. The multi-directional, multi-stage compaction serves to provide the interlocking between the straw fibres and the method, involving the use of a feeding device to a pre-chamber, also enables longer strands of straw, than are commonly used, to be compressed in the apparatus without the problems conventionally associated with longer lengths of straw. Providing multi-directional, multi-stage compaction enables the use of much smaller and faster hydraulic cylinders, lowering power requirements and enabling the apparatus to be trailer-mounted for towing on the road to the source of raw material rather than requiring the raw material to be brought to the source. This avoids the cost of moving, for example, straw in baled form, thus avoiding the need for baling and transportation of a relatively undense material. Preferably, the apparatus will be made in a modular arrangement so that, by interchanging appropriate elements, machines of different capacities and throughput can be assembled. One example of a machine constructed in accordance with the present invention will now be described with reference to the accompanying informal drawings " in which:- Figure 1 is a partially-sectioned diagrammatic end elevational view; Figure 2 is a partially-sectioned side elevational view; and. Figure 3 is a partially-sectioned plan view of the apparatus, with the prime mover, hydraulic power lines, control switches and feeding device being largely omitted for clarity. A cylindrical hopper (not shown) has a sweep arm or paddle (not shown) , which sweeps the material to be compressed into a pair of feed chambers arranged substantially vertically below the hopper. Each feed chamber 1 feeds the material into a respective first chamber 2 of rectangular cross-section. In each first chamber 2 is positioned a horizontal hydraulic ram 3 having a head 4, the ram 3 being driven by hydraulic pressure in a double acting cylinder 5. The ram 3 is shown in Figure 1 in a central position in which it would have partially compressed material horizontally towards an end portion 6 of the chamber 2 and into vertical chambers 9. A closure plate 7 follows the movement of the ram 3 to close the chamber 2 behind the ram head 4 to prevent material entering behind it and then fouling the return motion of the ram. Corresponding second rams 8 are positioned in respective vertical chambers 9 and are movable by hydraulic pressure in respective cylinders 10 to compress the partly compacted fibrous material into respective main chambers 11 below the second pre-chambers 9. Each second chamber 9 has a closure plate 12 moving with the respective ram to close the chamber behind the head 13 of the ram as in the first chambers and for the same purpose. A double-acting main ram 14 slides to and fro horizontally under hydraulic pressure in corresponding cylinder 15, to alternately compress pre-co pacted material in each of the main chambers 11. The material is compressed, in the direction of arrows A, into cylindrical briquettes which are pressed through respective cylinders 16, each comprising, at least at an end portion thereof, a pair of semi-cylindrical shells 17, the shells being squeezed together or allowed to move apart under the action of the pressure of compacted fibre in the cylinder 16 by respective hydraulic pressure actuated clamps 18, the pressure in the clamps being controlled if desired to adjust the density of the briquettes. The respective movements of the hydraulic rams are controlled by electrical, electromechanical, pressure sensing or like switches suitably positioned and arranged to synchronize the movements of the rams. Preferably, when the second rams 8 operate, the first rams 3 withdraw to allow a fresh charge of material to be fed into the respective first chambers while the immediately preceeding charge is being compacted into a briquette. Each second ram 8 has, attached to it, a rod 19 extending into the corresponding feed chamber 1 to agitate the fibrous material therein, to prevent any blockage of the feed chamber. The machine of the example has been found to generate far less heat than conventional briquetting machines and thus is capable of operation on materials having a greater moisture content than previously acceptable.

Claims: CLAIMS 1. Briquetting apparatus in which material to be briquetted is fed to a compressing chamber (11) , the apparatus comprising first (3) and second rams (8) movable in directions transverse to one another to partially compress the material; and a third ram (14) movable in the compressing chamber (11) in a third direction transverse to the first and second directions to further compress the material and force it through an extended opening (16) at the end of the compressing chamber; characterized in that the material is fed to a first pre-chamber (2) separate and offset, in the directions of both the first and second rams, from the main chamber (11) , the first ram (3) moving through the first pre-chamber (2) to compress the material into a second pre-chamber (9) disposed immediately adjacent the compressing chamber (11) , and the second ram (8) moving through the second pre-chamber (9) to compress the material into the compressing chamber (11) . 2. Apparatus according to claim 1, wherein the first pre-chamber (2) has a dimension in the direction of movement of the second ram (8) less than the stroke of the second ram (8) . 3. Apparatus according to claim 1 or claim 2, wherein the second pre-chamber (9) has a dimension in the direction of movement of the third ram (14) substantially less than the stroke of the third ram (14). 4. Apparatus according to any of claims 1 to 3, wherein the first pre-chamber (2) has a dimension in the direction of movement of the third ram (14) less than the stroke of the third ram (14) . 5. Apparatus according to any of claims 1 to 4, wherein the third ram (14) comprises a double-acting ram moving in alternate directions to compress material in a pair of main chambers, one at each end. 6. Apparatus according to any of claims 1 to 5, including a feed device for feeding material vertically under gravity into the first pre-chamber. 7. Apparatus according to any of claims 1 to 6, wherein the first pre-chamber (2) is detachable from the apparatus to enable first chambers of different sizes to be used. 8. Apparatus according to any of claims 1 to 7, wherein the stroke lengths of the first (8) and/or second (8) rams are adjustable. 9. Apparatus according to any of claims 1 to 8, wherein the swept volumes of the first (2) and/or second (9) chambers are adjustable. 10. Apparatus according to any of claims 1 to 9, wherein the first (3) and/or second (8) rams have respective closure plates (7,12) movable therewith and positioned to close the respective chamber behind the operating face of the ram when the ram is extended, to allow the next charge of material to be prepared by the feed device or first ram respectively in advance of the return of the first ram and second ram respectively.

Inventors: COOKSEY CLIVE RICHARD CAMPBELL, COOKSEY, CLIVE, RICHARD, CAMPBELL
Applicants: FIBA COMPACTA LTD, FIBA COMPACTA LIMITED
Application year: 1986
Main classification: B30B11
IPC codes: B30B11