DK172294B1 - Method of pelleting - Google Patents

Description

in DK 172294 B1

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a method of pelletizing feed in which the material or mixture of materials to be pelleted is conditioned at elevated temperature in a reaction vessel prior to pelletizing, thereby compressing the material in the reaction vessel by the action of a transport element such that a working pressure acting on the material and the material mixture, settles at the outlet end of the reaction vessel, which pressure acting on this amount of material is then lowered at 10 relaxation to a reduced, underpressure pressure.

It is well known that dusty, powdery and similar substances can be converted by pelletizing into forms which are easy to store and better to use. For this purpose, the original material, e.g. forced through holes in matrices, thereby preventing movement by the frictional resistance, so that the material is compressed. After passing through, the 20 strings thus produced are then cut to the required lengths with knives moving relative to the die to obtain pellets. In this way, e.g. flour-shaped and powdered materials, which can only be fed to animals whose disadvantages are accepted, are processed into pellets which are advantageously used as feed.

Prior to pelletizing, a conditioning is frequently performed.

One of the main purposes of conditioning is the positive influence on the physiological properties of the feed or its components, that is, it can be digested by the animals. Also, in order to make the pelleting operation successful, it is usually necessary to perform a pre-conditioning, which significantly affects the compression operation, the compressibility of the components, the strength of the pellets and thus the quality of the feed (IFF report no. 1 "Das Pelletieren von Mischfutter ", DK 172294 B1 2 published by the Futtermitteltechnik Research Institute of the International Research Community Futtermitteltechnik eV (IFF), Frickenmiihle, 3300 Braunschweig-Thune).

The conditioning or preparation is intended to compensate for varying moisture content of the raw material in the mixture, to improve particle elasticity, to reduce molding (compression) resistance, to build bonding forces at moisture bridges, to partially alter strength and to mobilize adhesive properties.

The corresponding conditioning, which is also performed on materials other than feed, is usually due to a heating and a supply of moisture. In the so-called short-time conditioning, the material throughput through the conditioner is usually less than 1 minute; the conditioning is performed in this case e.g. using a mixing screw. For long-term conditioning 20, the mixing is done in advance, the conditioning is then carried out in a larger container in which the material is moved relatively little. The residence time for long-term conditioning is at least 10 minutes, but can be a multiple thereof. Thereafter, a short-term conditioning is frequently performed prior to introduction into the pelletizing machine.

In all these cases, atmospheric pressure mainly prevails during conditioning. Even when the material is physically compressed by extruders or the like, it is still more or less unobstructed in connection with the ambient atmosphere.

A further disadvantage of some of the aforementioned conditioning means is that the passage through the conditioning means cannot be readily adapted to changing operating rates of the pelletizer. In the case of a sudden higher performance of the pelletizing machine, the throughput through the conditioning means, e.g. also increased, resulting in a shorter residence time of the material in the same. The shorter residence time can be e.g. 5 is not easily compensated for at higher temperature or higher humidity since the steam, at an increased vapor supply, will partially evaporate before it can permeate the material and interact with it.

10 However, it is known to mold the material at the pressures and temperatures of the conditioning. However, in such a procedure (FR-A-651 699) a special press is waived; rather, the shaping of the string takes place in the channels in which the higher pressure and the higher temperature also prevail. The product has an irregular shape, which after the shaping process is brought back to normal pressure and thereby expands.

Similar conditions apply to a process of the kind mentioned above (US-A-4,696,634). In this process, briquetting must take place at elevated pressure and elevated temperature, so that the formed food tablets or briquettes then expand into the mold and spring out of the mold. This process has various disadvantages.

1. It is technically expensive as this briquette device must also be kept under elevated pressure.

30 2. Due to the fact that the construction is expensive, obviously only relatively low pressures and relatively low temperatures corresponding to the low pressures can be worked. Thus, in the recess, column 2, line 34 is at a temperature of 240 ° F (115.6 ° C). At these low temperatures, not all conditioning functions (eg eradication of germ DK 172294 B1 4, etc.) can be achieved within a reasonable time frame. Because of this, conditioning should also be possible at higher temperatures.

5 3. As the pre-formed particles are still expanding, they have no fixed size.

The object of the invention is to provide a method which is simple to carry out and which provides pills of a precisely defined size.

The way in which the object according to the invention is achieved is that the conditioning is carried out at temperatures up to 170 ° C, especially 150 ° C, and that the pelleting after 15 relaxation at atmospheric pressure follows in a pelletizing machine.

The material is thus compressed in the reaction vessel of the transport element, e.g. by means of a transport screw or compression screw, in such a way that a material plug is formed. Enclosed steam, which is either introduced from the outside or produced as a result of the moisture contained by heating, cannot escape or can only escape with difficulty from this material plug. In this way, this vapor pressure can assume values that are substantially higher than atmospheric pressure under certain circumstances. The material can therefore assume a temperature here which is substantially higher than 100 ° C without the reaction vessel having to be hermetically sealed, which could impede the continuous transport of material through this container or render it impossible. In this way, temperatures of 170 ° C, especially up to 150 ° C, can easily be reached. The conditioning is advantageously carried out at temperatures of about 120 ° C.

35 DK 172294 B1 5

The required heat can be obtained by heating the reaction vessels from outside, by heating means in the reaction vessel, by heat of friction during transport and / or by feeding the material in the compression region a pressurized gaseous or liquid fluid, especially water vapor.

The moisture content of the material under conditioning is preferably about 10 to 30% by weight.

10 In the compressed area, the material has a substantially constant pressure.

Only at the outlet of the container does a pressure reduction take place, which acts on the material disposed. Thus, the pressure acting on the material is reduced only for the material leaving or leaving the reaction unit, while the pressure in the reaction vessel retains the original values so that the process operates continuously. Only then does the pelleting take place.

In a particularly simple embodiment, a reaction vessel having one or more outlet openings of a constant cross-section is used. The outlet opening can e.g. be an outlet opening from an extruder having a relatively small cross-section so that the plug, as a result of the material transport at the outlet end, is formed here, which, despite the continuous working method, allows the material to be kept here at a higher pressure and thus at higher temperature.

30

Outlet openings, if multiple, may be holes in a die from which the material is discharged from an extruder.

If a reaction vessel having one or more variable cross section outlet openings is used, the conditioning can simultaneously be optimally adapted to the working speed of the pelleting machine DK 172294 B1 6 and / or other working parameters. Such parameters are the power consumption of the machine's operation, temperature, degree of expansion, pellet quality or other parameters. However, of course, a control or control of the pill quality can also be achieved by changing other parameters if the departure cross section cannot be changed, e.g. in the case of a normal extruder.

The departure cross-section can be set either manually or automatically controlled, as it is possible to carry out the automatic control as a function of said parameters or of other parameters.

In a further advantageous embodiment, a so-called expander is used.

Such an expander is known in another context (DE-PS 3,529,229, DE-OS 3,554,298), so that the details of this expander do not need further discussion.

20

The known expander serves other purposes, e.g. the treatment of oilseeds and oilseeds for extracting edible oil. In this case, the expander must also essentially serve to produce intermediates, which need only be further processed after intermediate storage and possibly for a longer period of time. Therefore, in the known expander, it is firstly necessary to cool and dry the intermediates. For subsequent treatment, the material must be heated and moistened again.

30

In this conditioning, a compression must be obtained to provide a higher density and a better cell disintegration or cell degradation, in order to achieve better extraction.

35 DK 172294 B1 7

Surprisingly, the known expander can now also be used for conditioning material for compressing pills, and this immediately before compression, although in that case completely different goals are pursued with the conditioning. In the method according to the invention, e.g. the purpose of conditioning prior to compression is to change the strength of thermal treatment, to soften the raw fibers and partially dissolve the proteins to activate binding forces. Surprisingly, it has been found, according to the invention, that these objects can as well be achieved with the known conditioning process. An optimal adjustment of the working speeds of the expander and the pelletizer is possible. For example, When the pelletizer speed is increased, the throughput speed of the expander can also be increased. In order for good conditioning to still be carried out, e.g. the hydrostatic pressure of the fluid increases and more steam is added. Due to the higher temperature achieved in this way, the necessary conditioning takes place faster.

20

A further surprising result is that germs are also killed at the same time as the conditioning according to the invention, thereby making the feed hygienic and sterile. Thus, this surprising effect is neither anticipated nor suggested in any way by the known process.

The expansion unit used according to the invention acts as an expander and therefore has the advantage that the pressure and also the temperature are adjustable. This is very important in order to be able to precisely and selectively adjust the conditioning effect with which the physiological properties of the feed should be influenced or selectively altered. Also, the passage can be controlled, which is not necessary, or at least not sufficiently possible, by pre-coupled pelletizing presses or extruders. The additional advantage of allowing the expansion unit to be placed directly in front of the pelletizer is that the material leaving the expander should not be cooled and dried and then heated and moistened again, but can be immediately treated without any waste of time. or quality degradation.

In this case, the latter advantage and other of the other advantages mentioned above arise not only with an expander having a controllable cross section, but also when 10 constant cross sections are used in the process.

However, it is not absolutely necessary to use the expander for the invention. As stated above, it is possible to avoid the steam supply lines if the material is heated to sufficiently high temperature otherwise.

The conditioning can be carried out at temperatures up to 170 ° C and with controlled humidity. In this case 20, the conditioning can be performed selectively in such a way that, on the one hand, harmful enzymes are destroyed or neutralized, but valuable substances, e.g. proteins, on the other hand, do not lose in quality.

25 In many cases, a mixture of many substances in feed is treated. In this case, it may be convenient to condition only a partial flow of the material to be compressed into the expander. This is e.g. in the case when a partial flow is to be treated or conditioned at high temperatures and pressures, e.g. to destroy harmful enzymes. Another part must be subjected to a more gentle conventional conditioning so that the substances in this part stream are not damaged. Eg. In particular, valuable proteins or vitamins will not be passed through the expander. In many cases, a partial flow of the material need not be conditioned at all if the material is already in a form suitable for pelletizing or for addition to the main material.

Whether the total material or only a partial flow is fed through the expander and conditioned depends on the characteristics of the individual material components and whether these material components have been separated or already mixed in advance.

An advantageous embodiment of an apparatus for use in the method according to the invention is characterized in that the conditioner and the pelletizer are directly combined, so that the conditioned material can pass directly into the pelletizer, e.g. may fall into the pelletizer if the conditioner is placed above the machine. In the case of the outlet opening, the conditioner may have a ring slot, a flat slot or other types of narrowed outlet openings. The pelletizer may be a flat die press or a ring die press. If the conditioner and the pelletizing machine are spatially separated, a continuous conveyor, in particular a worm conveyor, a scraper bottom conveyor, a pneumatic conveyor system, a belt conveyor or a second conveyor known per se, is suitably disposed between the two machines. A plurality of such conveyors may also be arranged one after another if the spatial arrangement so requires.

Especially when the material leaves the conditioner in the form of strings, a comminution apparatus which commits the material in such a way that it can advantageously be processed in the pelletizer may be disposed between the conditioner and the pelletizer.

35 DK 172294 B1 10

The invention will now be described in more detail with reference to the drawing, in which: FIG. 1 shows a basic design of a pelletizing machine known per se. FIG. 2 shows an embodiment of the apparatus used in the method according to the invention with a flat die press; FIG. 3 shows another advantageous embodiment with a ring die press and FIG. 4 shows another type of connection between the conditioner and the pelletizer.

For a better understanding of the invention, the prior art design of a pelletizing machine 20 is first described with reference to FIG. First

On a machine frame 1 is attached a flat die 2, provided with holes 3, through which the material is forced, after it is compressed with roller rollers 4. The starting material, e.g. can be dust-shaped, thereby being filled 25 from above through the opening 5 in the housing 6. The housing 6 is also attached to the machine frame 1.

In a manner not shown in the figure, a pivot drill 7, which is connected to a corresponding drive (not shown), is attached to the machine frame 1. This pivot drill 7 with a vertical shaft 8 connected thereto can be pivoted by the drive about 1 in FIG. 1 is a vertical axis.

On the vertical shaft 8 a ball head 9 is fixed so that it cannot rotate with respect to the vertical shaft 8 (thus it can only rotate with it), but is axially displaceable on the vertical shaft 8 and can be height-adjusted by springs 10, a hydraulic nut 11 and spacer rings 12 by introducing hydraulic fluid or closing it via line 13 of the hydraulic 5 nut 11. The roller rollers are secured to shafts 14 in such a way that they can rotate freely about these horizontal shafts and thus roll on the die or on the layer of material as the roller head 9 rotates about its vertical axis. They are also provided with notes or material receiving grooves 15 to facilitate the compression operation.

The compressed material passes in the form of strands through the two holes 3 of the die and is subdivided into sections 15 by interrupting devices 16 which rotate with the ball head.

FIG. 2 shows an embodiment of the apparatus used in the method according to the invention in which a conditioning apparatus 40 is arranged over the pelletizing machine 20. This conditioning apparatus has a cylindrical housing 21 and a filling opening 22. In the housing 21 there is a worm conveyor 23 which can be operated with a motor 24.

25 Several pipes 25 through which steam can be introduced from a steam source 26 lead into the wall of the housing 21. The steam supply through the pipes 25 can be controlled by valves 27 by means of elements not shown in the figure.

At the outlet, the housing 21 has a constriction 28 which may be partially or completely closed by a tapered valve plate 29.

The taper plate 29 is thereby pressed against the opening 28 by a hydraulic piston 30 to produce a back pressure against the material. In this case, the hydraulic pressure is produced by a device 31 which is again controlled by means of a control or regulating unit 32. This control or regulating unit 32 also acts on the steam generating unit 26. In the lower part of fig. 2, it is also shown that the pelletizing machine is driven by a motor 17 which drives a worm gear 18 which in turn drives a 5 ring gear 19.

The device works as follows. The material to be compressed is introduced into the filling opening 22 in the direction of the arrows 33, thereby forcing the worm 23, driven 10 by the engine 24, to the right towards the opening 28. Vapor is introduced through the steam pipes 25 to heat the material. Since a material plug is formed near the outlet of the worm, the pressure here is higher than the atmospheric pressure, so that material temperature above 100 ° C can be generated at which temperatures the material is conditioned.

The thus-conditioned material then falls in the direction of arrows 34 into the pelletizing machine 20, is compressed there and leaves the same in the direction of arrow 35.

Excess flow emitted with the material from the conditioner 40 may exit the apparatus through a vapor aperture 36 in the direction of the arrow 37.

In the embodiment of FIG. 3, the pelletizing machine 20 is a ring die press in which roller rollers 4 run on an annular die 3. In this embodiment, another external heating means 38 is shown, by which the conditioning apparatus 40 can be heated externally by an energy source 39. In this case, the heating can 30 is carried out by steam, inductively, by resistance heating or other known processes. Of course, the heating elements could also be arranged within the conditioning apparatus 40. If such heating elements 38 are provided, it is also possible in certain circumstances 35 to avoid the steam pipes 25.

13 DK 172294 B1

In the embodiment shown in FIG. 4, the conditioner 40 and the pelletizer 20 are spaced apart. Between the two devices is a belt conveyor 60 which is driven by a motor (not shown).

5 In FIG. 4, there is also shown a comminuting device 41 whereby the material dispensed from the conditioner 40 in the form of rigid material in order to be introduced into the pelletizing machine 20 in a state which permits optimal compression.

10

As already mentioned, the conditioning rate can be adjusted to the processing speed of the pelletizing machine 20 by controlling the speed of the conditioner 40 of the conditioner 40. In order that the conditioner can still take place under favorable conditions, the steam supply into the conditioner can be controlled accordingly.

In comparative experiments, a number of feedstuffs were compressed with and without the conditioner. In this case, the treatment time in the conditioner 40 was 2 seconds, the temperature of the housing 21 was 122 ° C, while the vapor pressure in the conditioner 40 (expander) was 30 bar. The results were as follows.

Pfost Kahl

Feed_slide hardness Kimtal (germ / g)

Swine feed without expander 6.0% 5.0 kp 67.0 million with expander 1.4% 12.0 kp 0.002 million

Non-expanding parent feed 25.0% 1.0 kp with expander 2.4% 8.0 kp

Poultry feed without expander 6.4% 1.0 kp with expander_2, 6% _2.09 kp_ 25 DK 172294 B1 14

As the table shows, the pills made using the expander are not only significantly more abrasion resistant but also have a higher Kahl hardness. What is more important is that the number of germs is also drastically reduced.

In this way, e.g. salmonella, which is found in the raw material, is effectively killed.

In summary, it can be stated that the method of the invention allows for conditioning which can be performed better and easier as well as cheaper than the prior art.

In another embodiment of the invention, there is provided a new use of a known expander by which good conditioning of materials for pelletizing machines is made surprisingly and very advantageously, which ultimately leads to better feed value utilization.

Claims (8)

A method of pelletizing feed, wherein the material or mixture to be pelleted is conditioned at an elevated temperature in a reaction vessel prior to pelletizing, whereby the material in the reaction vessel is compressed by the action of a transport element such that a working pressure acting on the material or material mixture, settles at the outlet end of the reaction vessel, which at this amount of pressure acting on this material is then lowered by relaxation to a reduced, underpressure pressure, characterized in that the conditioning is carried out at temperatures up to 170 ° C, especially 150 ° C, and following the pelleting after relaxing at atmospheric pressure follows in a pelletizing machine. Process according to claim 1, characterized in that the material in the compressed region is supplied with a pressurized gaseous or liquid fluid. Process according to claim 2, characterized in that water vapor is used as a fluid. 25 Method according to one or more of claims 1-3, characterized in that the conditioning is carried out at temperatures of approx. 120 ° C. Process according to one or more of claims 1-4, characterized in that the material has a moisture content of about 10 to 30% by weight during conditioning. Process according to one or more of Claims 1 to 5, characterized in that only a partial flow of the material to be compressed in the reaction vessel is conditioned. Process according to any one of claims 1-6, characterized in that a reaction unit is provided which is characterized by a valve element which is designed as a pressure head which closes or at least restricts the outlet opening of the reaction vessel during the formation phase of work. the ground pressure (P) and is connected to a backpressure element. Method according to claim 7, characterized in that a counterpressure element is used, the counterpressure effect (P ") counteracting the container pressure (P) as long as inwardly of the claim P> P" is satisfied, so that the printing head is moved away from the container outlet opening, and the pressure head after meeting this requirement or after the ratio P <P "is first met is returned to the closing position of what is then a higher pressure (P") than (P) and an equilibrium state P = P "is produced with the result that a constant material discharge is obtained via the discharge gap formed between the pressure head and the container flange.