EP0801984A1 - Process and device for preparingcereals for grinding - Google Patents

Abstract

The method involves creating a sealed packing of the grain in the scrubbing chamber (111). Bearing strips on the scrubbing rotor (105) are formed of alternate fields of cams (112) and spiral conveyors (113) so that the cams mainly move the individual grains and the conveyors create an axial movement. The movement of the grains is improved by cams on the scrubbing chamber working with those on the rotor. The scrubbing intensity is changed by altering the gap between the bearing strips and the rotor and/or by positioning or regulating the backlog forces at the outlet (102). The grain is scrubbed in respective dry and wet stages.

Description

Technical field

The invention relates to an apparatus and a method for preparing grain for grinding, in particular all wet and dry stages of cleaning and wetting before intermediate storage in stand-off cells.

State of the art

• die Aussiebung von Sand und Schrollen
• das Auslesen von verschiedenen Fremdpartikeln, zum Beispiel von Steinen, Sämereien und Schalenteilen
• das Entfernen von anhaltendem Schmutz
• Befeuchten des Getreides von der Lagerfeuchtigkeit(z.B. 10-12%)auf die Vermahlungsfeuchtigkeit (auf über 15% Wassergehalt)
• Abstehen des Getreides während 12 bis 48 Stunden
• eventuell auch eine Abscheuerung oder Abschälung einzelner Schalenteile oder der ganzen Kornschale.

The preparation of the grain for grinding, in particular according to the system of high-level milling, comprises several process stages:

• the sifting of sand and clods
• the reading of various foreign particles, for example stones, seeds and shell parts
• removing persistent dirt
• Moisten the grain from the storage moisture (e.g. 10-12%) to the grinding moisture (to over 15% water content)
• The grain is left to stand for 12 to 48 hours
• possibly also abrasion or peeling of individual shell parts or the entire grain shell.

The grain of grain basically has a triple shell structure. The outermost shell consists of epidermis, longitudinal cells, transverse cells and tubular cells, which make up about 5.5% of the whole grain. This is followed by a middle double layer, the so-called dye layer, and a colorless layer, for which about 2.5% of the grain is assumed. The innermost layer is 7% of the grain weight and is called the Aleron layer. There remains the germ with 2.5% and the big rest, the Flour core, is about 82.5% of the whole grain. A well-known problem area in the production of wholemeal, dark and light flours as well as haze and semolina is the plant germ because the germ has a high fat content. The germ is a component of value and is suitable, for example, for the extraction of oil. It is the fat, however, that, when the germ is broken open, limits the shelf life of the ground products, especially when there is a high germ content. The miller strives to remove all plant germs as gently as possible in the grinding process. The grain should therefore be carried with the germ to the first grinding without damage as far as possible.

The recent past has been shaped by two tendencies. First, by an economically justified reduction in the number of machines or Units for cleaning or grinding preparation. The goal was to use only dry readers, a cereal wetting and the smallest possible stand-off cells. In accordance with the second tendency, the reverse was suggested, similar to rice milling, of peeling and polishing the ground grain over many steps almost to the flour core.

For example, according to DE-PS No. 1 164 210, it was proposed to completely remove the outermost layers. Depending on the type of grain, 3.2 -5.7%, i.e. partly the entire outer shell, is removed by repeated moistening, stripping and sifting. The removal of such a large shell part must be prepared and accompanied by a targeted and repeated treatment of the grain, whereby in addition to the moisture, heat was also applied over a sufficient exposure time with moderate movement.

According to CH-PS No. 640 750, the applicant herself proposed, as it were, a middle way to peel away 6-10% of the grain, or 50-60% of the grain shell, before grinding. Four successive process steps are proposed for this: dry cleaning - damp peeling - intensive wetting roll milling. In practice, however, this procedure could not be implemented for economic or economic reasons.

In the case of an even older solution, according to GB-PS No. 1 258 230, it is proposed, in order to increase the yield, to remove the various shells by repeated "batchwise" processing. Although this process of full peeling has been known for over two decades, it has not been used in practice.

Recently, according to US Pat. No. 5,025,993, attempts have been made again to carry out part of the operations of the previous grinding process within the grinding preparation by systematic and repeated total scrubbing and peeling. However, very large-scale practical tests showed no advantages, at least in relation to the overall economy of a mill. On the contrary, when the grain is completely peeled, very moist shell fractions arise, which have to be treated separately and partly dried. The majority of the experiments showed no higher yield of light flour or semolina. The effort for the grinding process itself cannot be reduced significantly. US Pat. No. 5,025,993 is based on the peeling and polishing practice of rice milling. The real disadvantage is that each individual machine has only a very small throughput, so that with higher outputs, e.g. 20 - 40 t / h a large number of individual machines are required.

Also known is a device for peeling and cleaning according to EP-A-12750, the drum shell of which alternately has areas of peeling elements protruding into the scrubbing space and forced conveying means (peeling blades) for the axial movement of the material to be treated. The drum is surrounded by a sieve.

Presentation of the invention

The object of the invention was now to improve the grinding preparation without disadvantage for the grinding, in particular to bring the grain to a high level of purity without breaking the grain even with a high throughput. The task was also to enable the input parameters that can be influenced for grinding to be made more constant.

The invention relates to a process for the scrubbing and grinding preparation of cereals for the production of, for example, wholemeal flours, light flours, vapor and semolina, the cereals being cleaned in several stages, the grinding moisture being produced by metered addition of water, being fed to a stand-off cell and grinding, and is characterized in that the grain is scrubbed in a first dry and a second moist or wet stage before it stands. the main amount of water being added before or during the second stage, and the grain for the moist or wet scrubbing being temporarily stored for 1 to 120 minutes and only being led to standoff after the second moist or wet stage.

With the invention it could be confirmed that the actual basic operations: cleaning - wetting - standing - grinding for the extraction of the most varied of grinding products have been mastered at a high level for decades, until today. But all the alleged optimization efforts of recent times, with many overlaps or intermingling of the basic operations, only yielded advantages for special sub-goals. Overall, however, these brought a step backwards for miller practice. For this reason, the suggestions mentioned were rejected in practice. As part of the industrial processing of all plant seeds, especially the various types of grain, it is recognized that high-level milling places the highest demands. The grain of rice has a rounded, emphatically convex shape, so that it is not technically difficult in rice milling to grind all parts of the husk down to the flour core. The rice is traditionally polished. Because of the deep furrow, the wheat grain has both concave and convex shapes, the furrow enclosing about 20-30% of the whole grain husk. The furrow section in particular cannot be reached during a work operation in the manner of rice polishing. The shell portion lying inwards in the concave must be loosened and sieved out as before during the multiple grinding. The grinding and polishing of the wheat grain for grinding thus offers no immediate advantages.

• Entfernen von allen Fremdsämereien
• Entfernen von allen Verunreinigungen und Schalenteile
• Reduzierung der bakteriologischen Verunreinigungen
• Erhaltung eines intakten Kornes.

The second misconception of all the suggestions mentioned concerned cleaning itself. Grain cleaning has four main objectives:

• Remove all foreign seeds
• Remove all contaminants and shell parts
• Reduction of bacteriological contamination
• Preservation of an intact grain.

For obvious reasons, the dirt of vegetable grains is on the surface and, apart from the furrow, never inside the grain. In principle, the flour core is sterile. If the grain layer is now peeled off, all dirt and all microbes are removed only with a superficial logic. Since the various layers of the grain's husk can be removed most effectively with moisture, but especially after 12 to 24 hours of standing, any more intensive peeling has been carried out either only after it has stood or with a multiple interplay of peeling and moistening. It was overlooked that the number of microorganisms is not a simple question of statistics. Due to their own reproductive capacity or doubling, for example, within 30 - 60 minutes, with ideal conditions such as nutrient base, warmth and moisture, a number of germs above the permissible value can occur within 24 hours. Many microbes actually have optimal propagation conditions that match the optimal condition for preparation for grinding.

The grain should first be cleaned dry as well as possible and only then brought to a higher moisture level with network water and this to act on the skin. The main part of the dirt substance can be removed in dry cleaning. At the same time, the number of bacteria, if this is initially increased, is reduced. In a period of 5 to 120, preferably 10 90 minutes of intermediate storage, the number of germs can at most be doubled. The second wet or wet cleaning subsequently allows the maximum possible removal and thus a grain mass of extremely high purity to be achieved with regard to contamination, be it permanent dirt or microbes, so that the subsequent grain of the whole grain in the stand-off cell can be over 12 to 48 hours without any disadvantage depending on the optimal grinding requirements. The whole processing process is thus carried out in a first impure sector, as well as a second completely clean sector, starting with the transfer of the cleaned grain to the rest cells, divided. The cleaning is concentrated and carried out and completed in the shortest possible time.

The invention also allows a number of particularly advantageous configurations. The grain is preferably subjected to surface processing in the moist or wet cleaning. Part of the outermost grain shell is chafed away and the abrasion is immediately separated from the grain, preferably 0.3 to 2% being chafed away from the grain. In the dry cleaning process, the grain is very particularly preferably subjected to a surface scrubbing which prevents the outer grain shells from being chafed away. The cleaning is thus returned to what it should be, namely to bring each individual grain as well as the whole grain mass to a higher degree of purity without damage to the grain. Any exposure of the endosperm or breakup of the germ is avoided. At the same time, the grain is wetted by adding network water, so that the wet or wet, second cleaning can be carried out more efficiently. The shell structure of the grain remains intact with the exception of a part of the outermost shell and protects the endosperm until the first grinding passage. In many cases, the removal of a part of the outermost shell means that residues of environmental toxins that are concentrated there can be removed at the same time. One removes only impure parts in the cleaning, so that this impure fraction can be led to a special disposal. The rest of the grain as a flour core, germ and also bran are valuable components and can be optimally used for specific recycling. According to a further design idea, a gaseous medium flows through the grain at least temporarily, preferably via circulating air, in the intermediate depot during the intermediate storage. This means that any increase in the number of bacteria can be suppressed during the interim storage period. For special requirements, wet or wet cleaning can be carried out in several or multiple stages. In this case, an intermediate storage of 1 to 10, preferably 2 to 5 minutes is sufficient, which can take place at least partially in a network device. Furthermore, heat, or possibly cold, can be brought into the material to cool it down and to bring it to predeterminable values either via the network liquid or via the gaseous medium. The grain moisture is preferably measured after the wet or wet cleaning, using a computer with a predetermined Moisture compared and corrected the addition of water using appropriate control means. You can set a pre-selectable grinding moisture in this way.

The invention further relates to a device for preparing grain for the production of, for example, flour, haze and semolina, the grain being cleaned in several stages, the grinding moisture produced by metered addition of water being stored in a stand-off cell and being fed to the grinding, and thereby being characterized in that it has a first dry cleaning or scrubbing as well as a second moist or wet cleaning, the second cleaning also being arranged in front of the stand-off cells and in the second cleaning an intermediate depot between a device for adding water and a cleaning machine.

The invention further relates to the use of an advantageous device for scrubbing grain with a scrubbing rotor having working elements and a scouring jacket which together form a scrubbing space through which the grain is conveyed through the working elements via an inlet to an outlet, characterized in that the scrubbing rotor alternately has fields of cams protruding into the scrubbing space and forced conveyors for the axial movement of the grain.

The device allows a number of particularly advantageous configurations. The working elements of the scouring rotor are alternately formed in the circumferential direction as fields of protruding cams and helical forced conveyors. The abrasion jacket preferably also has fields of protruding cams which protrude in the abrasion space, the height of all working elements being of the same order of magnitude as the free distance (rotor play) between the working elements, e.g. are between 5 and 15 mm. The forced conveying means are advantageously arranged on carrier strips, which extend over the essential length of the scrubbing rotor and are preferably designed as a feed screw in the area of the inlet.

The rotor is designed as a hollow body and the feed screw is preferably provided with a larger screw depth compared to the forced conveyors in the subsequent scrubbing room. The working elements can be formed on a plurality of support strips, for example 6 to 10, which can be mounted on the rotor and each extend over the entire length of the rotor and have corresponding cam fields and / or positive conveying means. The rotor can alternately have at least 3, preferably each 4, longitudinally extending fields of cams and forced conveyors in the circumferential direction. The scouring coat has on its entire surface either only scouring elements or can alternately in the circumferential direction z. B. each have 3 or 4 screen and scouring sections. The scouring jacket can consist of stationary, annular sieve sections and fields of cams which can be set against or set against the rotor, the tight packing of the grain layer preferably being produced by an adjustable, preferably adjustable flap.

The invention will now be explained in more detail with reference to several exemplary embodiments.

Brief description of the invention

die Figur 1

diagrammatisch eine Mahlvorbereitung;

die Figur 2

die feuchte bzw. nasse Stufe der Reinigung in grösserem Massstab;

die Figur 3,

3a und 3b an sich bekannte Schnitte durch ein Weizenkorn;

die Figur 4

eine kombinierte Trockenscheuerung mit anschliessender Befeuchtung;

die Figur 5

eine Kornscheuermaschine in grösserem Massstab;

die Figur 6

einen Schnitt VI der Figur 5;

die Figur 7

eine weitere Ausführungsform mit mehrstufiger Reinigung;

Show it:

the figure 1

diagrammatically a meal preparation;

the figure 2

the damp or wet level of cleaning on a larger scale;

the figure 3,

3a and 3b known cuts through a grain of wheat;

the figure 4

a combined dry scrubbing with subsequent humidification;

the figure 5

a grain scrubber on a larger scale;

the figure 6

a section VI of Figure 5;

the figure 7

another embodiment with multi-stage cleaning;

Ways of Carrying Out the Invention

Reference is now made to FIG. 1. The so-called raw fruit 1 is made available for processing via a distribution conveyor 2 into the respective raw fruit cells 3, 3 'to 3 ^IV etc. The raw fruit is only partially or not cleaned grain. The grain is usually freed of the coarsest contaminants by sieves and aspirations without having to clean the individual grains. The raw fruit cells are also used to provide various types of grain, which are subsequently mixed together via quantity regulators 4 according to the preselected quantity and percentages via a collecting screw 5. The raw fruit mixture is then lifted over an elevator 6 and guided over a scale 7 into the first pre-cleaning stage 8 of dry cleaning, which is a combination of a size classification in the upper part and a weight classification in the lower part, as described, for example, in EP-PS No. 293 426. The raw fruit is introduced via an inlet 9 of the pre-cleaning stage 8, 10 larger foreign constituents, so-called rolls, being separated off via an outlet 11, fine sand being discharged, 12 stones being discharged via the outlet and 13 fine dust being removed via an exhaust line. The grain is subsequently via a connecting line 14 or. 14 'fed into an interior 15. Most foreign seeds such as round grains and long grains, oat barley, sweet peas, etc. can also be used to read out raden and broken grain. The main grain is fed as the main fraction to a dry scrubbing machine 16 via an inlet 17, where an intensive surface cleaning of each individual grain takes place for the first time. The dry abrasion is carried away via a collecting funnel 18 and a discharge line 19. The grain is freed of loose shells and all scouring abrasion in a tarar 20 and continuously fed into a network device 22 via a conveyor 21 as dry cleaned goods. The network device 22 can be of any type, it is important that a regulating device 23 can be used to add a quantity of network water that can be precisely determined via a computer 24 via a corresponding network water line 25. It can be in addition to or instead of water steam can also be used via a steam feed line 26 for wetting the grain. The network device can be implemented in accordance with the proposal in Swiss Patent 686 229, to which reference is made in full here. The network device 22 has a drive motor 28, an entry conveyor 29 and a network chamber 30 with acceleration rotors 31 rotatably mounted therein. The freshly wetted grain is then stored in an intermediate depot for 40 to 120 minutes. After a preselectable time, the grain is transferred to a wet or wet scrubbing machine 42 via a discharge metering device 41, with 0.2 to 2% being scrubbed away from the grain, depending on the task, the scouring dust also being carried away directly above the collecting funnel 43 here. Another interesting design idea is that an additional treatment can be carried out in the intermediate depot 40 with conditioned air 44 via an air treatment 45 with controlled temperature and air humidity, preferably in recirculation mode. Furthermore, it is also possible to create a special gas atmosphere in the intermediate depot 40, for example with CO ₂ via a gassing device 46. A shifting device could also be assigned to the intermediate depot 40, but it is preferably used in continuous operation. The grain temperature is determined by a probe 47, as is the effective grain moisture after cleaning, which is measured, for example, by a microwave measuring unit 50. Both values are fed to the computer 24 via a data bus system 51, which also coordinates all operations on the basis of higher-level specifications. In the intermediate depot, the grain can be heated to a constant temperature of 20'C and cooled if necessary. With the entire device, a corresponding correction can now be made in the case of alternating moisture in the grinding grain after the wet or wet cleaning above the actual moisture value, a comparison with a desired value either via the air treatment 45 or via the network device 22. Until then, all process steps within the unclean sector UR had been carried out with the shortest possible residence time of at most two hours. The grinding grain, which has now been cleaned and wetted to the highest standards, is subsequently transferred to the mill side, which is a clean sector R, and a further elevator 60 is used to store a distribution conveyor 61 in a preselectable stand-up cell 62 to 62IV, in which the grain is now, for example, for Is left to stand for 12 to 24 hours. The ground grain is then fed through a flow control device 70, a horizontal conveyor 71 and an elevator 72 to a further network device 73, only 0.1 to 0.5% of water being added, for example, to moisten the surface of the grain. After a short period of rest in a bi-depot 74, the mill input power is recorded with the so-called bi-scale 75 and transferred to the first grinding stage or the first grinding roller mill 77 via a safety magnetic separator 76. Thereafter, the grinding products are obtained in a manner known per se using the system of high-level milling.

FIGS. 3, 3a and 3b each show a section through a grain of grain known per se. The grain mainly consists of the flour core 80, the aleurone layer 81, a seed husk 82 and a fruit husk 83, furthermore a seedling 84. The special characteristic of the wheat is the so-called furrow 85, which accounts for 20 or more percent of the different layers 81 - 83 includes.

FIG. 4 shows a combined machine, the dry scrubbing machine 16 and the network device 22 being combined as an assembly as in FIG. 1. It can also be seen from FIG. 4 that the two units also have a control and regulating unit. Both the degree of abrasion and the value of the wetting can be controlled as specified.

In Figures 5 and 6, the dry scrubbing machine 16, respectively. the wet or wet scrubbing machine 42 is shown on a larger scale. The scrubber has a working housing 100 with an inlet 101 and an outlet 102 for the cleaned grain. A cylindrical scouring jacket 103 is arranged in a stationary manner within the working housing 100, a rotor 105 being rotatable about an axis within the scouring jacket 103, which is mounted in bearings 106 on both end sides and is driven by a drive motor 28 via a belt exaggeration 107. The work housing 100 also has control and service doors 108 on both sides and opens in the middle part into the collecting funnel 18, via which the scrubbing drive can be removed. The scouring jacket 103 consists of sieve sections 109 and rasp surfaces 110, the rasp surfaces preferably being able to be moved towards or away from the rotor 105 for adjusting the effective working gap between the rotor 105 and 110. In the example shown in Figures 5 and 6, the scouring jacket 103 alternately has three screen and scouring sections respectively. Rasping surfaces 110 so that the scouring abrasion is removed from the working space 111 immediately after it is formed by the screen sections. The rotor 105, in turn, is constructed in a 4-part form, with each rasp surface 112 and conveying means 113, with the exception of one inlet section, being arranged alternately in the working space 111. The conveying means 113 extend over the entire length of the working space 111 and are supplemented by corresponding feed screw elements 114 distributed over the entire circumference, and form a feed screw 115 in the area of the inlet 101. In the outlet area 116 a backflow flap 117 is attached, which is the simplest Cases by adjustable weights 118 is adjustable for a particular peeling intensity.

FIG. 7 shows an embodiment with multiple wet or wet scrubbing. The network device 22 'or 22' has a correspondingly enlarged network chamber 30 'or 30' 'to ensure a water exposure time of 1 to 10, preferably 2 to 5 minutes. The grain is moved intensively during the intermediate storage by mechanical impact and friction effects and prepared step by step. This makes it possible to remove the desired portion of the shell more gently, which is optimal for the ground products to be extracted. As can also be seen from FIG. 7, the scrubbing machine 42 'can also be arranged in an obliquely upward direction. After cleaning, the amount of water still missing for the grinding moisture is advantageously added via a further network device 22 ″ ″. The water content is measured when it emerges from the network chamber 30 ″ and brought to the desired value via a control device 23 ″.

Tests have shown that depending on the desired quality of the end product or the raw fruit mixture used for this, the solution according to the invention enables better control and more precise predetermination of the end products, so that the entire grinding process can be carried out with greater reproducibility, in particular with a higher degree of automation. It is possible to influence the input parameters of the regrind within a very small range to keep. It has proven to be very advantageous if the following values are continuously measured or monitored. These are the water content, color and ash of the grain, as well as the temperature and the bulk density, whereby the hardness of the grain may also be recorded before or after cleaning. In many cases, the standby time can be reduced with the new invention without disadvantages for the grinding.

Claims (9)

Process for preparing grain or grain, in particular wholemeal flour, light flour, haze or semolina, the grain being cleaned in several stages and moistened with a metered amount of water for preparation for grinding and being fed to a stand-off cell (62) and grinding, characterized in that that the grain material passes through all dry (8, 15, 16, 20) and all wet and wet (22, 40, 42) cleaning stages before being fed into the holding cell (62) and is fed to the grinding without further cleaning steps after the holding cell (62) . A method according to claim 1, characterized in that the grain is first cleaned dry and then moist or wet, the main amount of water being added before or during wet or wet cleaning, and the grain for wet or wet cleaning for 1 to 120 minutes is temporarily stored. Method according to one of claims 1 or 2, characterized in that the grain is surface-treated during the moist or wet cleaning and part, in particular 0.2 to 2% of the grain, of the outermost grain shell (83) is rubbed off and the abrasion is immediately separated from the grain becomes. Method according to one of claims 1 to 3, characterized in that the grain is scrubbed during dry cleaning - without chipping away the grain shell (83). Method according to one of claims 1 to 4, characterized in that during the intermediate storage at least temporarily a gaseous medium, in particular circulating air (44), flows through the grain and / or heats it to a certain temperature either via the wetting liquid or via the gaseous medium or if necessary is cooled. Method according to one of claims 1 to 5, characterized in that the grain is cleaned wet or wet in two or more stages and, if necessary, the grain is wetted in each case between the stages, in particular the grain moisture after the wet or wet cleaning stage (n) measured, compared with a target value via computer means (24) and the water addition is corrected via corresponding control means (23). A process for the continuous scrubbing of grain or grain and for preparing the grinding to light flour, haze and semolina, in particular for use in a method according to claim 3 or 4, wherein the grain is in an approximately cylindrical scouring jacket (103) with a rotor (105 ) is moved from an inlet (101) to an outlet (102, 116) and is alternately scrubbed and sieved in the circumferential direction on the scouring jacket (103), characterized in that the grain material is conveyed from the inlet (101) to the outlet by conveying means (113, 115) (102, 116) are forcibly conveyed and processed by rasping surfaces (112) arranged to the conveying means (113) and the abrasion is repeatedly separated with the rotating rotor movement. A method according to claim 7, characterized in that the grain - seen from the outlet area (116) - is backed up and a dense, approximately 1-5 grain thick grain layer is built up in the working space (111) between the rotor (105) and the scouring jacket (103). Device for grinding preparation of grain or cereals for the production, among other things. of wholemeal flours, light flours, haze and semolina, in particular for carrying out a method according to one of claims 1 to 6, the device comprising at least one cleaning device (8, 15, 16, 20, 22, 42) for cleaning the grain, at least one stand-off cell (62) and a grinding device (77), characterized in that - seen in the direction of passage of the grain through the device - all dry (8, 15, 16, 20) and all moist or wet (22, 42) cleaning devices in front of the Stand-off cell (62) are arranged and the stand-off cell (62) is arranged in front of the grinding device (77).

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