GB1571463A

GB1571463A - Method and apparatus for the treatment of extruded particulate articles of vegetable or animal matter

Info

Publication number: GB1571463A
Application number: GB16487/77A
Authority: GB
Original assignee: Buehler AG
Current assignee: Buehler AG
Priority date: 1976-04-26
Filing date: 1977-04-20
Publication date: 1980-07-16
Also published as: FR2349286A1; NL7703383A; CH600792A5; DE2634874B2; FR2349286B1; DE2634874C3; DE2634874A1

Description

(54) METHOD AND APPARATUS FOR THE TREATMENT OF EXTRUDED PARTICULATE ARTICLES OF VEGETABLE OR ANIMAL MATTER (71) We, GEBRUEDER BUEHLER AG, of 9240 Uzwil, Switzerland. a Swiss Body Corporate, do hereby declare the invention. for which we pray that a patent may be granted to us. and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a method for the treatment of particulate articles such as pellets, granulates. and fine-grain products made from vegetable or animal raw materials by extrusion, such for example as animal feed pellets or cubes.

The treatment is to bring about structural changes or reactions. Agglutination can be mentioned as an example of structural change. Sterilisation is a very important reaction in the treatment of animal feed pellets or cubes, or other similar particles.

It has alreadv been proposed for the feed cubes produced from an extruder to be dried in a steam-heated drum drier which is arranged in a vacuum container (British Patent 1003097). This method is very costly both as to plant and in operation. Therefore its use is limited to animal experiments.

In normal cases the very moist and brittle feed cubes produced from the feed cube press are first dried and cooled to give them greater cohesion and to lessen their tendency to stick together. The feed cubes can be conveyed and processed further in this condition. For sterilisation they should be again brought to the necessary temperature and moisture. so that a considerable outlay on heat energy would be required.

The invention makes it possible to obviate or lessen these disadvantages in a surprisingly simple way. The method proposed by the present invention for the treatment of extruded particulate articles of vegetable or animal matter which are extruded are at an elevated temperature with respect to the ambient temperature. includes the steps of placing the pellets or cubes or other articles on a conveying support whilst still at or nearly at that temperature, conveying them by the conveying support for a preselected dwell time in a heat insulated warming chamber and heating the warming chamber to compensate the articles for heat losses.

Thus the high temperature produced during extrusion pressing is utilised (and it is in this sense that the term elevated temperature is herein used). It is no longer necessary. or hardly necessary, in the case of feed cubes to heat them up and instead it is sufficient to compensate for heat losses.

This results in a great saving in thermal energy.

Since the particles are put on to a moving conveying support, the height of the layer of cubes remains relatively limited and they are not moved relatively to one another, so that there is no substantial risk of damage.

The product is discharged from the moving conveying support without difficulty even if the feed cubes are still moist and brittle.

They can be cooled by conventional means.

With most of the product, the heatconditioning i.e. the heating-up achieved during pressing, is sufficient for sterilisation purposes. But from time to time it is found that concentrations of germs are present. By keeping the product warm for a sufficient predetermined length of time these concentrations can be avoided.

If the surfaces contacted by the feed cubes and also the void spaces are given temperatures which are 10 C + 2"C (preferably 10 C, desirably about 10 C) higher than those of the cubes, condensation on parts of the warming chamber or the conveying support is obviated, although the hot products passing through have a water content of 20% - 25% by weight.

In the case of cubes which have temperatures of 75" - 85" C after pressing, this condition can be achieved if the warming chamber is heated with water or steam flowing in pipes, with a temperature amounting to 1000C - 105"C; the dwell tine amounts to 2 - 6 minutes.

The invention also concerns an apparatus for the treatment of extruded particulate articles of vegetable or animal matter which when extruded are at an elevated temperature with respect to the ambient temperature. The apparatus proposed by the invention includes a holding apparatus for the articles for a preselected dwell time after extrusion of the articles, the holding apparatus comprising a heat insulated warming chamber, a heating device for heating the warming chamber, a belt conveyor for supporting and conveying the articles thereon in the warming chamber, a feed device for placing the articles on the conveyor within the warming chamber and discharge means for discharge of the articles from the apparatus.

This is a simple apparatus, which by its nature can operate reliably.

In a particular constructional form of the invention, the supporting run of the conveyor belt is trough-shaped. In this way the direction of the reaction forces supporting the layer of product'on the said conveyor belt is very advantageous.

If the side walls of the warming chamber are inclined inwardly upwardly above the conveyor belt, this also results in advantageous reaction forces acting on the product. Because of very slight settling of the product during conveying, the product does not press against these walls or at least over the greater part of the conveying distance does not press against those walls.

The special combination of a troughshaped conveyor belt and inclined side walls makes for greatly improved conditions at the lower side corners of the conveying cross-section. In contrast to conditions which prevail with a rectangular conveying cross-section. product cannot readily collect in that region, to remain behind when the apparatus is emptied. Such residues could form new breeding ground for bacteria.

To define the trough-shaped form, it is possible to use alternately inclined crossed troughing rollers, i.e. supporting rollers which are positioned in an inclined manner with their axes arranged alternately down towards the right from the upper left and towards the lower left from the upper right.

The end drums, that is to say the driving drum and the end guide drum. of the conveyor belt are advantageously of cylin drical construction. which makes production easier. In this case there is provided between one end drum and the feed device a forward transition section of conveyor belt for changing over from a straight cross section to a trough-shaped cross-section.

Thus the product is put on to the conveyor belt only where the cross-section of the conveying belt is already troughed.

Before the other end drum also there is provided a transition section for the conveyor belt for changing from the troughshaped to the straight cross-section. and the discharging means follows this other end drum. At this transition the previously compact, bed of product is lowered and opened out, and hence loosened, which improves the discharge conditions from the conveyor belt into the discharge means.

The holding apparatus provided by the invention is advantageously used in an installation where it is arranged downstream of an extrusion press which is constructed as a feed cube press with a press roller and an annular press mould. Usually the warming chamber will be followed by a feed cube cooling apparatus.

The drawings show in a diagrammatic manner by way of example one form of apparatus embodying the invention.

Figure 1 depicts an apparatus for the production of feed cubes, Figure 2 shows the operating principle of the feed cube press in order to make its operation clear, Figure 3 is a cross section on an enlarged scale of the holding apparatus on the line III-III of Figure 1, Figure 4 is a like section on the line IV-IV of Figure 1, and Figure 5 illustrates on a smaller scale the arrangement of the heating pipes in a section through a side wall along the line V-V of Figure 3.

The installation shown in Figure 1 consists mainly of a feed cube press 11, a holding apparatus 12 and a feed cube cooling apparatus 13. The outlet 15 of the feed cube press 11 is connected by a down pipe 16 to the feed device 17 of the holding apparatus 12.

The discharge means of the holding apparatus 12, which discharge means is constructed as a funnel 18, is connected directly to the inlet 19 of the feed cube cooling apparatus 13. In an arrangement bypassing the holding apparatus 12, the outlet 15 of the feed cube press 11 is connected by way of a down pipe 21 and the funnel 18 directly to the inlet 19 of the feed cube cooling apparatus 13. A diverter flap 22 connects the outlet 15 of the feed cube press 11 either to the down pipe 16 or to the down pipe 21.

The feed cube press 11 has a feed screw 25 and a mixer 26 driven by a geared motor 27.

The mixer 26 is provided with a steam introduction device 28. From the mixer 26 an inlet compartment 30 leads to the annular, driven, rotating press mould 31 which is shown in side sectional view. Figure 2 shows the press mould 31 from the front in section with its mould holes 33. The pressure rollers 32 are mounted for rotation on a stationary voke 35 which also carries feed blades 36.

knives 37 are secured on the housing (not shown) of the feed cube press 11.

The holding apparatus 12 (Figures 1. 3. 4) has a warming chamber 40 with heat insulated walls 41. In the chamber is a conveying support in the form of a convevor belt 42 and having two cylindrical end drums, that is to sav a driving drum 43 and an end guide drum 44. There is also shown a tensioning roller 45. The driving drum 43 is driven by a variable drive unit 47 by way of a chain drive 48.

The material-supporting run 53 of the conveyor belt 42 is trough-shaped over the conveying section 51. The trough shape is defined by supporting rollers 53, 54 arranged as crossed troughing rollers, viz at an inclination with their axes arranged alternatelv from the upper left to the lower right and from the upper right to the lower left. Between the end guide drum 44 and the feed device 17 provided with a closure flap 56 the conveyor belt 42 has a forward transition section 57 for the transition from the straight cross-section to the troughshaped cross-section. Upstream of the driving drum 43 the conveyor belt 42 has a further transition section 5X for the transition from the trough-shaped cross-section to the straight cross-section. The discharge means 18 follows this driving drum 43.

The side walls 61 of the warming chamber 40 are inclined inwardly upwardly above the supporting run 52 of the conveyor belt 42 so as to converge. Metal plates 64 are mounted so as to be spaced from the internal side of the insulating walls 62 of these side walls 61 and the roof 63. These plates form heating compartments 65 in which lateral tube coils 67. 68 are provided and also an upper tube coil 69. A tube coil 70 is arranged between the supporting run 52 and the return run 73 of the conveyor belt 42. Figure 5 shows in a diagrammatic manner the heating compartment 65 of the side wall 61 and the tube coil 67 arranged therein with its inlet 75 and its outlet 76.

Arranged at the lower edge of the surface 64 of the heating compartments 65 are stripping elements 77 which form the lower lateral corners of the conveying crosssection between the side walls 61 or their surfaces 64. and the supporting run 52 of the conveyor belt 4'.

Inspection windows 82 are arranged at the end walls 80, 81 of the warming chamber 40 to allow operators to observe the interior.

The inlet of the feed cube cooling apparatus 13 leads to the cooling duct 91 provided with an outlet portion 92 which usually has a cube breaker. Arranged at the cooling duct 91 i9 a suction box 94 connected to a fan 96 be wtiy of a suction conduit 95. The outlet 15 of the feed cube press 11 is connected by way of a suction conduit 98 (indicated by a chain dotted line) to the suction conduit 95.

The operation of the apparatus will be explained by reference to an example.

Before starting the installation, the warming chamber is heated with the closure flap 56 closed. Water at a temperature of 105"C circulates through the tube coils 67-70.

A feed mixture is supplied to the feed screw 25 at a throughput rate of 12 tonnes per hour and this conveys the product into the mixer 26 where it is heated with steam from the steam introduction device 28 to a temperature of 60" - 85"C with a water content of 22% by weight. The product falls through the inlet compartment 30 into the driven press mould 31 which rotates in the direction of the arrow 101. The feed blades 36 divide the product at two places and the product is carried along by the rotating mould 31, drawn in at the press rollers 32, which are driven by the friction of this product, and extruded through the holes 33.

The extruded product is cut by the stationary knives 37 into feed cubes of the desired length. The extrusion operation increases the temperature of the feed cubes to 80" 90"C.

The feed cubes fall from the outlet 15 of the feed cube press past the diverter flap 22 into the down pipe 16 and (with the closure flap 56 now open) through the feed device 17 into the warming chamber 40. They are stacked on the trough-shaped conveying section 51 of the conveyor belt, for example up to the chain-dotted line 103 shown in Figure 3.

The conveyor belt 42 is driven in a uniform manner by means of the variable drive unit 47. Because of a slight sinking of the layer of product there is almost no contact with the metal plates 64. Owing to the water circulating in the tube coils 67-70, the feed cubes retain their temperature of e.g. 85"C and their water content of 22%, without condensation occurring.

On the transition section 58. the bed of cubes is substantially reduced in height so that the product is loosened-up to a satisfactory extent before being discharged. After a dwell time of three minutes from infeed, set by the variable drive unit 47, the feed cubes are discharged into the funnel 18 at the driving drum 43.

They fall through the inlet 19 into the cooling duct 91 where they are continuously cooled in the usual way by external air drawn in transversely to the cooling duct 91.

The cooling air is drawn in by the fan 96 by way of the suction box 94 and the suction conduit 95. Clouds of steam from the feed cube press 11 and if appropriate from the holding apparatus 12 are removed by the suction conduit 98 from the outlet 15 of the feed cube press 11.

Continuous inspection shows that the bacteria rate at the funnel 18 keeps constantly below 200 per gram of mixed feed, which is extremely low, although the treatment time at a high temperature is short, so that the quality of the product is not prejudiced.

It has been found very advantageous to select the time of dwell and the water temperature in such a manner that in the holding apparatus 12 the temperature of the feed cubes is raised by 2"C, which provides securitv against condensation.

If the flap 22 is changed-over, the feed cubes can pass direct from the feed cube press 11 into the feed cube cooling apparatus 13.

To facilitate cleaning, the walls 41 of the warming chamber 40 can be constructed so as to swing outwards or to be removable.

WHAT WE CLAIM IS: 1. Method for the treatment of extruded particulate articles of vegetable or animal matter which when extruded are at an elevated temperature with respect to the ambient temperature, the method including the steps of placing them on a conveying support whilst still at or nearly at that temperature. conveying them by the conveying support for a preselected dwell time in a heat insulated warming chamber and heating the warming chamber to compensate the articles for heat losses.

2. Method according to claim 1 wherein the surfaces that make contact with the articles in the warming chamber and the void spaces therein are heated to a temperature which is higher than the temperature of the articles.

3. Method according to claim 2 wherein the temperature to which the said contact surfaces and void spaces are heated is 10 C + '"C above that of the articles.

4. Method according to claim 3 wherein the temperature to which the said contact surfaces and void spaces are heated is about 10 C above that of the articles.

5. Method according to any preceding claim wherein the said elevated temperature is 75 - 85"C and the warming chamber is heated bv flow of water or steam at a temperature of 100" - 105"C through heating tubes.

6. Method according to any preceding claim wherein the said preselected dwell time is from 2 to 6 minutes.

7. Method according to any preceding claim wherein the articles are cooled in a forced draught cooler after leaving the warming chamber.

8. Method for the treatment of extruded particulate articles of vegetable or animal matter, substantially as hereinbefore described with reference to the accompanying drawings.

9. Apparatus for the treatment of extruded particulate articles of vegetable or animal matter which when extruded are at an elevated temperature with respect to the ambient temperature, the apparatus including a holding apparatus for the articles for a preselected dwell time after extrusion of the articles, the holding apparatus comprising a heat insulated warming chamber, a heating device for heating the warming chamber, a belt conveyor for supporting and conveying the articles thereon in the warming chamber, a feed device for placing the articles on the conveyor within the warming chamber and discharge means for discharge of the articles from the apparatus.

10. Apparatus according to claim 9 wherein the load bearing run of the belt conveyor is trough-shaped.

11. Apparatus according to claim 10 wherein inclined supporting rollers define the trough-shaped form, the axes of the rollers being arranged alternately downwards towards the right from the upper left and downwards towards the left from the upper right.

12. Apparatus according to claim 10 or claim 11 wherein the end drums (that is to say the driving drum and the end guide drum) of the belt conveyor are cylindrical in shape and between one end drum and the feed device a forward transition section for the conveyor belt is provided for the transition from the straight to the trough-shaped cross-section of the conveyor belt.

13. Apparatus according to claim 12 wherein upstream of the other end drum a transition section for the conveyor belt is provided for the transition from the troughshaped to the straight cross-section, the discharge means following this other end drum.

14. Apparatus according to any of claims 9 to 13 wherein the warming chamber has side walls that converge above the conveyor belt.

15. Apparatus according to any of claims 9 to 14 including a cooling apparatus for the articles arranged downstream of the holding apparatus.

16. Apparatus according to any of claims 9 to 15 including a press for the extrusion of articles arranged upstream of the holding apparatus.

17. Apparatus according to claim 16 wherein the press has a press roller and an annular press mould, the arrangement being such that the articles go from the press mould to the holding chamber by way of the feed device.

18. Apparatus for the treatment of extruded particulate articles of vegetable or animal matter which when extruded are at an elevated temperature with respect to the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. feed cube press 11. Continuous inspection shows that the bacteria rate at the funnel 18 keeps constantly below 200 per gram of mixed feed, which is extremely low, although the treatment time at a high temperature is short, so that the quality of the product is not prejudiced. It has been found very advantageous to select the time of dwell and the water temperature in such a manner that in the holding apparatus 12 the temperature of the feed cubes is raised by 2"C, which provides securitv against condensation. If the flap 22 is changed-over, the feed cubes can pass direct from the feed cube press 11 into the feed cube cooling apparatus 13. To facilitate cleaning, the walls 41 of the warming chamber 40 can be constructed so as to swing outwards or to be removable. WHAT WE CLAIM IS:

1. Method for the treatment of extruded particulate articles of vegetable or animal matter which when extruded are at an elevated temperature with respect to the ambient temperature, the method including the steps of placing them on a conveying support whilst still at or nearly at that temperature. conveying them by the conveying support for a preselected dwell time in a heat insulated warming chamber and heating the warming chamber to compensate the articles for heat losses.

ambient temperature, the apparatus being constructed arranged and adapted for use and operation substantially as hereinbefore described with reference to the accompanying figures whether including or devoid of the extrusion press and the forced draught cooler or either of them.

19. Particulate extruded articles of vegetable or animal matter when made by use of the method or of an apparatus as claimed in any one of the preceding claims.