Patent Application
20080160157
The present invention relates to a facility and a method for the continuous production of starch-based, fat-based, or protein-based bulk foodstuffs or feeds or technical intermediate products made of a starch-based, fat-based, or protein-based compound having water according to the preamble of claim 1 or claim 30.
In the production of starch-based, fat-based, or protein-based bulk foodstuffs or feeds or technical intermediate products made of a starch-based, fat-based, or protein-based compound having water, essentially two parameters are of great significance for the product quality. These are, on one hand, the specific mechanical energy (SME) introduced into the product during the method and, on the other hand, the bulk weight or the pellet density of the produced product.
Known methods for producing the products cited at the beginning use one or more extruders for this purpose, for example. The SME is supplied to the product in the processing chamber of the extruder via rotating screw shafts by shear forces. The extruders used here typically have an intake area, a processing area, and a shaping area.
U.S. Pat. No. 5,714,187 describes a method and a facility for controlling the quality of a kneaded and compression-molded feed. The facility contains a screw press and optionally a pelleting press. The various processing areas of the facility are implemented having sensors to detect multiple product properties. Settings (setting parameters) on the devices of the facility producing the feed are changed on the basis of these detected product properties. This change of the setting parameters is either performed manually according to the principle of “trial and error” or automatically on the basis of an empirically ascertained and statistically analyzed formula. However, an isolated influence of the fill level of an extruder without changing the other process parameters is not discussed here.
DE 19714713 describes a device for treating feed having an expansion housing, which has pressure buildup and relaxation zones, as well as a material intake and inlet nozzles for water steam and a screw having differently implemented areas for pressure buildup, compression, and expansion. The device described here also has a backup element or blocking part, which encloses the screw and forms a constriction in the form of an annular gap, which prevents escape of steam via the material intake. However, a measuring device for determining product parameters and modulation of an adjustable barrier via a modulation device as a function of the product parameters is not discussed.
The SME is influenced by the following processing and system parameters (processing variables):
raw material properties (formula)
moisture (product moisture)
configuration of the extruder screws
screw speed
fill level.
The raw material properties or the formula are typically predefined and therefore basically may not be influenced.
Influencing the SME via the moisture (product moisture) is expensive, because additional water added to the product must be removed again in subsequent drying with additional energy expenditure.
Adaptation of the screw configuration is connected with reconfiguration work at least on the screw shafts and is very complex.
A change of the screw speed results in a change of the throughput. However, one typically operates at the speed maximum to achieve maximum throughput. A reduction of the speed would therefore result in throughput losses.
Therefore, only influencing the fill level remains. However, in the extruder-based methods known up to this point, influencing the fill level is not possible without a change of the other processing variables.
Adaptation and/or adjustment of the SME without having to change the other processing variables cited is therefore practically impossible.
The present invention is based on the object of allowing, in the facility cited at the beginning and/or the method cited at the beginning, adaptation or adjustment of the SME and monitoring and control of the bulk density or the density (pellet density) of the product without changing other processing variables.
This object is achieved by the facility and the method according to claim 1 or claim 30, respectively.
The facility according to the present invention has the following sequential areas, along which the compound is conveyable:
According to the present invention, the facility has an adjustable barrier which inhibits the conveyance of the compound between the first area and the second area, and a measuring device is assigned to the third area, using which a product parameter may be determined, which is related to the bulk density and/or density of the bulk-type finished foodstuff or feed or technical intermediate product formed in the third area. According to the present invention, the measuring device is connected to a barrier activation device via a data transmission link, to adjust the adjustable barrier as a function of the product parameter which may be determined by the measuring device.
This adjustable barrier between the first area and the second area allows the fill level and thus the SME in the first area to be influenced independently of all other processing variables. Online monitoring as well as influencing the fill level and the SME during the method if necessary are even possible.
Therefore, additional freedom is obtained in the adjustment or control of the method in relation to the known typical methods and facilities, to ensure uniformly high product quality.
The measuring device is best linked with a barrier actuation device by means of a data transmission path, in order to set the adjustable barrier as a function of the product parameters determinable by the measuring device.
The data transmission path preferably has a data processing unit for processing the product parameter data received by the measuring device into control data for the barrier actuation device. It is especially advantageous for the data processing unit to be programmable, so that it can be adjusted to various measuring devices and actuation devices.
The measuring device preferably has a sampler for taking a predetermined bulk material sample volume, and filling the bulk material sample volume into a measuring cell. As a result, samples can be taken from the stream of bulk material that forms in the third zone at constant intervals, thereby enabling a quasi-continuous inspection of samples, and hence product monitoring and, if necessary, a correction of process conditions, in particular the SME.
The measuring device preferably has a scale for determining the mass of the bulk material sample volume. This makes it possible to determine the apparent density of the product as defined.
The measuring device can also exhibit a source and receiver for electromagnetic (EM) radiation, between which there is an EM radiation path that traverses the measuring cell. The weakening of introduced EM radiation of a prescribed intensity and change in its propagation rate while passing through the bulk material sample volume can also be drawn upon for indirectly determining the apparent density.
In another advantageous embodiment, the bulk material in the bulk material sample volume in the measuring cell of the measuring device can be fixed, and the measuring device has a fluid path between a fluid inlet and fluid outlet that traverses the measuring cell. Measuring the pressure drop in the fluid and throughput of the fluid as it passes through the bulk material sample volume in the measuring cell yields its fluid resistance, in particular its pneumatic resistance, which can also be drawn upon for indirectly determining the apparent density.
In another advantageous embodiment, the measuring device has a sound source and sound receiver, between which there is a sound path that traverses the measuring cell. As with the EM waves, the weakening of introduced sound waves of a prescribed intensity and change in their propagation rate while passing through the bulk material sample volume can be drawn upon for indirectly determining the apparent density.
In a particularly advantageous embodiment that enables a practically continuous monitoring of apparent density, the measuring device exhibits an impact surface arranged in or after the third zone, which extends into the bulk material stream formed in the third zone. It also has a sound receiver for recording the sound spectrum of the impact noise, and the data processing unit is provided with a spectrum analyzer for analyzing the recorded sound spectrum. The sound spectrum of the impact noise is characteristic for the apparent density (“sound fingerprint”), and can be drawn upon for monitoring the latter.
In another particularly advantageous that enables a quasi-continuous monitoring of apparent density, the measuring device contains an isolating device for isolating the bulk material particles of the bulk material stream formed in the third zone, as well as an optical imaging system for acquiring a projection surface of the respective individual bulk material particles. In this case, the data processing unit is a spectrum analyzer for analyzing the recorded projection surface spectrum.
The data processing unit preferably contains a memory for storing a setpoint for the respective product parameter corresponding to a setpoint apparent density of the bulk material, as well as a comparator for comparing an actual value for the respective product parameter acquired by the measuring device with its setpoint.
The product parameter measuring processes mentioned above are preferably executed on the bulk material samples in the measuring cell in combination, making it possible to tangibly improve the correlation between the product parameters determined in the measuring device and the bulk density of the product to be monitored.
The adjustable barrier preferably involves an adjustable cross-sectional narrowing.
The third zone can be under a pressure less or greater than the saturation vapor pressure in the water contained in the mass. This makes it possible to manufacture the products described at the outset in an expanded or non-expanded form.
In a preferred embodiment, the first zone and second zone are comprised of the processing section of a multi-screw extruder, in particular a co-rotating two-screw extruder. This embodiment is characterized by the compactness of the plant.
In another preferred embodiment, the first zone consists of the processing section of a multi-screw extruder, in particular a counter-rotating two-screw extruder, and the second zone consists of the processing section of a single-screw extruder, a counter-rotating two-screw extruder or a gear pump. This embodiment permits a strong shearing impact, and hence a high SME input into the product, on the one hand, and a strong pumping action, and hence a strong pressure buildup in the product in the second zone, on the other.
A preconditioner is best connected in series with the multi-screw extruder. The preconditioner and the multi-screw extruder then together form the first zone of the plant according to the invention. The preconditioner preferably has two serially connected chambers. The initial materials are here wetted during a relatively short retention time of the product in the first chamber, while the water can act on the initial materials for a relatively long retention time in the second chamber.
The adjustable barrier is preferably arranged inside a longitudinal section of the multi-screw extruder or two-screw extruder in a location situated between ⅕ and ⅘, in particular between ⅖ and ⅗, of the overall length of the multi-screw extruder or two-screw extruder. This ensures that enough processing space for barrier-adjustable SME product input will be provided upstream from the adjustable barrier, and that enough processing space for product pressure buildup will be provided downstream from the adjustable barrier.
The adjustable barrier can also be arranged at the downstream conveying end of the first zone formed by the multi-screw extruder or two-screw extruder, or it can be arranged at the upstream conveying end of the second zone formed by the single-screw extruder, counter-rotating two-screw extruder or gear pump. As a result, the CME can be set to a relatively high level upstream from the barrier, while a strong pumping action exists downstream from the barrier, enabling a pressure buildup over a wide pressure range.
In another preferred embodiment, the adjustable barrier consists of a respective screw-free, rotationally symmetrical section of the screw or screws of the extruder, and of at least one detent that can move relative to the respective rotationally symmetrical section and has a recess complementary to the respective rotationally symmetrical section, thereby giving rise to a gap with adjustable nip width between the respective rotationally symmetrical section and the complementary recess of the detent. The movement of the detent relative to the rotationally symmetrical section allocated thereto makes it possible to easily set the locking effect of the barrier in the extruder from outside the extruder.
In a particularly advantageous embodiment, the plant according to the invention has a pressure-setting means for setting the pressure prevailing in the mass in the second zone. The pressure-setting means can be a device for changing the quantity of water present in the mass, in particular a device for selectively supplying or removing water vapor in or out of the second zone. This makes it possible to set the pressure in the product, which is especially important when the objective is to manufacture expanded extrudates with an apparent density determined by the content of water vapor and the pressure in the product.
Interconnecting the adjustable barrier (SME control module) and pressure-setting means (density control module) in this way makes it possible to independently influence the degree of cooking based on product processing (SME) on the one hand, and the density or apparent density of the product on the other. For example, both modules can be distributed within a single extruder (co-rotating two-screw extruder), or among two different extruders (SME control module at the end of a co-rotating two-screw extruder and density control module at the beginning of a counter-rotating two-screw extruder, a single-screw extruder or a gear pump).
The pressure-setting means preferably exhibits a feed line and a discharge line for supplying or removing water vapor in or out of the second zone, wherein the feed line and the discharge line can be optionally released or blocked. Specifically blocking or releasing the respective lines hence makes it possible to set the apparent density of expanded extrudates, or to prevent the extrudates from expanding.
In a particularly preferred embodiment, the pressure-setting means encompasses a feed line, which connects the second zone with a water vapor-generating system, a first discharge line, which connects the second zone with a vacuum system, and a second discharge line, which connects the second zone with a first zone, wherein the feed line and the first and second discharge line can optionally be released or blocked. Connecting the second zone with the first zone makes it possible to return the water vapor drawn from the second zone for setting the pressure back to the first zone, for example, especially to the preconditioner. This saves on energy on the one hand, and largely prevents the emission of highly odiferous vapor into the surrounding air.
In another particularly advantageous embodiment, the measuring device contains a pressure sensor in the third zone, wherein a pressure-setting means that can be used to set the pressure in the third zone is connected to the third zone. This makes it possible to further influence the expansion behavior of the product in the third zone.
In this case, the measuring device is connected with a pressure-setting means actuation device by a data transmission path in order to set the pressure-setting means as a function of the pressure determinable by the measuring device or one of the aforementioned product parameters in the third zone.
The data transmission path here contains a data processing unit in order to process the product parameter data or pressure values from the third zone received by the measuring device into control data for the pressure-setting means actuation device.
The forming unit is best a die plate with a rotating cutting blade. This makes it possible to manufacture the products described at the outset in the form of pellets with an adjustable apparent density by expanding to more or less of an extent, or not at all, as the product exits the die plate.
The method according to the invention has the following sequential steps in consecutive zones:
a) Conveying of the mass through a first zone, which exhibits a first processing section, wherein the mass is thoroughly mixed and kneaded through exposure to mechanical and/or thermal energy, and the water acts on the mass;
b) Conveying of the mass through a second zone, which exhibits a second processing section, wherein pressure is built up in the mass;
c) reshaping the pressure-impinged compound using a reshaping unit situated between the second area and a third area;
d) ejecting the pressure-impinged and molded compound into the third area;
according to the present invention, the specific mechanical energy introduction into the compound occurring in the first area is adjusted by adjusting a barrier inhibiting the conveyance of the compound between the first area and the second area, and in the third area using a measuring device, which determines a product parameter, which is related to the bulk density and/or density of the finished foodstuff or feed or technical intermediate product. According to the present invention, the barrier is adjusted as a function of the product parameter determined in the measuring device, the actual value of the product parameter determined in the measuring device preferably being compared to a predetermined setpoint value of the product parameter and the barrier being adjusted as a function of the actual value/setpoint value deviation of the product parameter.
Preferably, a bulk product sample volume is taken from the bulk product flow in the third area repeatedly during the production of the bulk-type foodstuff or feed. At least one of the following measured variables may be determined and used as a product parameter on the basis of this bulk product sample volume, which is preferably held in a measuring cell: mass of the bulk product sample volume; attenuation of electromagnetic radiation, in particular gamma radiation, during passage through the bulk product sample volume; propagation speed of electromagnetic radiation, in particular of microwave radiation during passage through the bulk product sample volume; pressure drop of a fluid, in particular of compressed air, during passage through the fixed bulk product sample volume; attenuation of mechanical waves, in particular of sound waves, during passage through the bulk product sample volume.
The sound spectrum of the impact noise which the bulk product flow generates in or after the third area when it hits or is deflected by an impact surface may also be detected as a product parameter. To this end, use can also be made of the sound spectra of the bulk material stream as it is being deflected into a pipe elbow of a pneumatic bulk material conveying system.
To acquire another product parameter, the particles of the bulk material stream are isolated from the third zone, wherein each bulk material particle is optically acquired separately, and the projection surface spectrum of the bulk material particles is then used as the product parameter.
As already mentioned, the pressure in the third zone can also be measured. It is especially easy to correlate with the apparent density or pellet density of an expanded product.
The pressure prevailing in the mass is best set in the second zone, wherein the pressure is preferably set by supplying or removing water vapor in the second zone, so as to change the water content or product moisture of the mass.
It is particularly advantageous to optionally supply the second zone with water vapor from a water vapor generating system, or bleed water vapor from the second zone to a vacuum system, or return water vapor to the first zone from the second zone.
Additional advantages, features and possible applications of the invention may now be gleaned form the following description of exemplary embodiments based on the drawing, which are not to be construed as limiting. Shown on:
The plant has the following zones along the direction of product flow:
Situated between the second zone 4 and the third zone 6 is a forming unit 5, with which the pressurized mass is formed into a specific shape before ejected into the third zone 6 (step c).
Also arranged between the first zone 2 and the second zone 4 of the plant is an adjustable barrier 3 that impedes the transport of the mass, along with a product parameter-measuring device S, a data transmission path L, a measured data processing device V, and a barrier actuation device A1. The measuring device S is used to measure a product parameter for the product exiting in the third zone 6. To this end, a sampler (not shown) is used to take a bulk material sample from the bulk material stream in the third zone 6 and transfer it into a measuring chamber or measuring cell. The preferably bowl-shaped sampler can also serve as the measuring cell.
The product parameter determined in the measuring cell can be any product parameter that correlates with the apparent density or (pellet) density of the product. The following parameters are among those that can be measured:
The measured data obtained in the measuring device S for the respective product parameters are supplied to the measured data processing device V via the data transmission path L. There, they are processed into actuation data for the barrier actuation device A1, which are then relayed to the barrier actuation device A1 via the data transmission path L to set the barrier 3 accordingly. This influences the respectively acquired product parameter. The respective product parameter can be controlled and monitored in this way.
The reference numbers on
The plant exhibits the following sections along the direction of product flow:
Along the product conveying direction, the two-screw extruder 7 driven by a motor 3 via a gearbox G exhibits a feed zone E, a cooking zone SME (SME-introduction zone), the adjustable barrier 3, a density-setting zone D and a pressure-buildup zone P. A pressure-setting means 11 is located inside the density setting zone D.
The density-setting means 11 is connected with the density-setting zone D of the extruder 7 on the one hand, and with a feed line 12, a first discharge line 13 and a second discharge line 14 on the other. The pressure-setting means can exhibit a retaining mechanism (screws conveying back into the extruder) to prevent product form exiting the extruder 7 along with aspirated vapor. A valve 12a in the feed line 12, a valve 13a in the first discharge line 13 and a valve 14a in the second discharge line 14 makes it possible to optionally supply or remove water vapor to or from the second partial processing section 7b of the extruder, wherein the removed water vapor is preferably returned to the preconditioner 1 via discharge line 14.
The following are allocated to or connected with the pressure-setting means 11:
The initial material (raw materials) for manufacturing the starch, fat or protein-based foodstuff or feedstuff has starch, fat or protein-containing raw materials, as well as water. These are either fed to the first zone 2 (see
Only a relatively small SME is introduced in the preconditioner 1, and the product is not cooked therein yet. The bulk of the SME introduction and actual cooking process only takes place in the first partial processing section 7a of the extruder 7.
The plant shown on
By comparison to conventional plants, arranging the adjustable barrier 3 between the first partial processing section 7a and the second partial processing section 7b of the extruder 7 according to the invention makes enables a decoupling of SME input adjustment and apparent density adjustment, i.e., SM input and apparent density (product density) can be set independently of each other.
As on
In addition, a pressure-setting means actuation device A2 can also be hooked up to the measured data processing device S by way of a data transmission path L in this first exemplary embodiment (as in the second exemplary embodiment on
The plant on
In the vapor jet pump 20, the vapor jet inlet 20a is connected with a water-vapor generating system (not shown) by means of a first vapor line 21, the vapor jet outlet 20b is connected with the preconditioner 1 by means of a second vapor line 22, and the suction inlet 20c is connected with the second partial processing section 7b by means of a third vapor line 23, wherein the first, second and third vapor line 21, 22, 23 each have a first, second and third valve (not shown), with which each of them can be optionally released or blocked.
In addition a fourth vapor line (not shown) linking the first vapor line 21 and the third vapor line 23 is provided, forming a bridge line (bypass line) around the vapor jet pump 20, wherein the fourth vapor line has a fourth valve (not shown), with which it can be optionally blocked or released.
If the bride line is blocked and vapor lines 21, 22 and 23 are released, the vapor jet pump is in suction mode, and siphons water vapor from the partial processing section 7b. During subsequent expansion in the forming unit 5, this leads to an increase in the product density or apparent density.
By contrast, if the bridge line and vapor lines 21 and 23 are released, and the vapor line 22 is blocked, the vapor jet pump is in the pressure mode, and expresses water vapor introduced via the vapor line 21 out of the water vapor-generating system into the partial processing section 7b. During subsequent expansion in the forming unit 5, this leads to a decrease in the product density or apparent density.
Depending on the desired apparent density, the density of the expanded extrudates (pellets) or the expansion degree on the forming unit 5 (e.g., die plate) can be continuously adjusted within a broad range.
As on
The plant on
The vapor jet inlet 20a of the vapor jet pump 20 is connected with a water vapor-generating system (not shown) by means of a first vapor line 21, while the vapor jet outlet 20b of the vapor jet pump 20 is connected with the preconditioner 1 by means of a second vapor line 22. The vapor line 21 contains valves 21a and 21b, which can be controlled as required.
The vapor jet pump 20 makes it possible to generate a vacuum at its suction inlet 20c. This vacuum is supplied via a third vapor line 23 to the partial processing section 7b of the extruder (second zone 4), and relayed to the third zone 6 or the cutting apparatus chamber 26 via a fourth vapor line 24.
The third vapor line 23 has attached to it a pressure or temperature sensor S23, which actuates a valve 23a in the third vapor line.
The cutting apparatus chamber 26 has attached to it a pressure or temperature sensor S26, which actuates a valve 24a in the fourth vapor line 24.
A fifth vapor line 25 also connects the water vapor generating system (not shown) with the partial processing section 7b of the extruder. As a result, vapor can be introduced directly into the extruder 7 (direct vapor). The fifth vapor line 25 contains a valve 25a, which is also actuated by the sensor S23.
The apparent density or pellet density of the manufactured bulk material can be controlled through the interaction between the vapor lines 23, 24 and 25 with the respective valves 23a, 24a and 25a, as well as their actuation via the sensors S26 and S23.
The valves 23a and 25a can also be replaced by a three-way valve.
This arrangement makes it possible to generate a vacuum in the second zone 4 (=extruder partial zone b) and/or in the third zone 6 (=cutting apparatus chamber 26) by means of the vapor jet pump 20. This vapor jet pump is operated using process vapor from the water vapor-generating system (not shown), and permits a complete return of the thermal energy of the extruder 7 and cutting apparatus chamber 26 generated by the SME.
Exposing the third vapor line 23 at the extruder and/or the fourth vapor line 24 at the cutting apparatus chamber 26 to a vacuum, and directly supplying the vapor to the extruder 7 via the vapor line 25 makes it possible to set the apparent density or pellet density of the bulk material generated by the cutting apparatus 26. The sensors S23 and S26 in conjunction with the valves 23a and 25a or 24a they actuate enable a variation of apparent density within wide limits.
The following ranges can typically be set using this system according to the third exemplary embodiment:
Apparent density from 200 kg/m3 to 650 kg/m3
Pressure in extruder from 0.5 bar to 10 bar
Pressure in cutting apparatus from 0.5 bar to 2 bar.
As on
The adjustable barrier 3 is comprised of:
Therefore, there is a nip 10 with adjustable nip width between the respective rotationally symmetrical section 8a and the complementary recess 9a of the detent 9.
In the example shown on
Axially shifting the detent 9 to the left makes the nip 10 smaller, and hence increases the fill level in the partial processing section 7a, thereby raising the introduced SME.
Axially shifting the detent 9 to the right makes the nip 10 bigger, and hence decreases the fill level in the partial processing section 7a, thereby lowering the introduced SME.
In this way, the barrier 3 that can be adjusted by changing the nip 10 makes it possible to set the SME introduced in the first partial processing section 7a independently of all remaining process variables, and in particular independently of the setting of product density or product apparent density in the second partial processing section 7b.
The SME control module 3 shown here essentially consists of two cylindrical detents 9, which are arranged one next to the other, with parallel-running cylinder axes. Each of the two detents 9 has two recesses 9a, which are complementary to a respective rotationally symmetrical section 8a of two parallel, intermeshing screws 8. The lower of the two cylindrical detents 9 is driven by a detent motor M4. At the ends facing away from the motor, each of the two detents 9 has a gear wheel 9b. The radius of the two gear wheels (spur gears) and their teeth are designed so as to intermesh. As a result, the upper detent 9 is driven by the lower detent 9 driven by the motor M4. This causes the actuated detents 9, 9 to move in opposite directions, so that the nip 10 between the rotationally symmetrical sections 8a and the complementary recesses 9a can be reduced or enlarged, depending on the rotational direction of the motor M4.
In the example shown here, the rotationally symmetrical sections 8a and the complementary recesses 9a are cylindrical.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102005010315.4 | Mar 2005 | DE | national |
This application is a U.S. national stage filing under 35 USC §371 of PCT International Application PCT/CH2006/000067, filed Feb. 2, 2006, and published under PCT Article 21(2) as WO 2006/092070 on Sep. 8, 2006. PCT/CH2006/000067 claimed priority from German application 10 2005 010 315.4, filed Mar. 3, 2005. The entire contents of each of the prior applications are incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CH2006/000067 | 2/2/2006 | WO | 00 | 8/31/2007 |
