Method and device for producing flour and/or semolina

Abstract

To produce flour and/or semolina, raw material is fed into a feed opening of a roller press. The milling gap of the roller press is fixed, or damping of at least one of the rollers with respect to the lateral deflection is set, such that a first subset of the fill containing finer milling material forms a packed particle fill in the milling gap. In addition, the setting is carried out in such a way that individual particles of a second subset of the fill containing coarser milling material are in contact with the first roller and the second roller of the roller press. Subsequently, the bulk material is milled into milled product in the roller press (9) and the milled product is discharged through a discharge opening.

Claims

1. A milling method for producing a milled product consisting of at least one of flour and semolina from a material selected from the group of materials consisting of cereals, cocoa, sunflower seeds and rice or combinations thereof, said method including the following steps: providing a high-pressure roller mill comprising: a feed opening and an outlet opening, a first roller and a second roller, wherein at least one of the first and the second rollers is mounted so as to be movable in a direction substantially perpendicular to a direction of rotation of the other of the first and the second rollers, such that a milling gap may be set between the first and the second rollers, providing a bulk supply of the material consisting of particles with a size distribution, wherein a first partial amount of the bulk supply of the material consists of finer material to be milled and a second partial amount of the bulk supply of the material consists of coarser material to be milled; setting the milling gap in such a manner that, during operation, the first roller and the second roller do not oscillate with respect to one another, wherein the milling gap is set larger than particle sizes of the first partial amount of the bulk supply of the material, and the milling gap is set smaller than particle sizes of the second partial amount of the bulk supply of the material; creating a material bed immediately upstream of the milling gap as a result of oversupplying material, by means of a filled material chute or funnel, whereby the first and the second rollers are able to draw material into the milling gap from a drawing in region; milling the material by means of applying pressure to the material in the milling gap, between the first and the second rollers of the high-pressure roller mill, to produce the milled product so that particles of the first partial amount of the bulk supply of the material are milled in a packed particle fill in the milling gap while particles of the second partial amount of the bulk supply of the material are milled by contact with both the first and the second rollers; and removing the milled product through the outlet opening.

2. The method as claimed in claim 1, wherein the first roller and the second roller rotate at different speeds.

3. The method as claimed in claim 1, wherein the step of setting the milling gap comprises setting an adjustable damping with reference to a deflection in the direction in which the or each of the at least one of the first and the second rollers is mounted so as to be movable so as to completely suppress any oscillation of the first roller and the second roller with respect to one another.

4. The method as claimed in claim 1, wherein, following the step of milling the material, conveying the milled product into a separating step for separation into finer milled product and coarser milled product.

5. The method as claimed in claim 4, further comprising conveying the coarser milled product back into the feed opening and/or a further high-pressure roller mill is connected downstream of the separating step for further milling of the finer milled product.

6. A miffing method for producing a milled product consisting of at least one of flour and semolina from a material selected from the group of materials consisting of cereals, cocoa, sunflower seeds and rice or combinations thereof, said method including: providing a high-pressure roller mill comprising: a feed opening and an outlet opening, a first roller and a second roller, wherein at least one of the first and the second rollers is mounted so as to be movable in a direction substantially perpendicular to a rotational axis of the other of the first and the second rollers, such that a milling gap may be set between the first and the second rollers, providing a bulk supply of the material consisting of particles with a size distribution, wherein a first partial amount of the bulk supply of the material consists of finer material to be milled and a second partial amount of the bulk supply of the material consists of coarser material to be milled; setting the milling gap in such a manner that, during operation, the first roller and the second roller do not oscillate with respect to one another, wherein the milling gap is set larger than particle sizes of the first partial amount of the bulk supply of the material, and the milling gap is set smaller than particle sizes of the second partial amount of the bulk supply of the material; feeding the bulk supply of the material to the miffing gap so as to create a material bed immediately upstream of the miffing gap due to an oversupply of the bulk supply of the material to the milling gap, and the first and the second rollers being able to draw material into the milling gap from a drawing in region located immediately adjacent the milling gap and within the material bed; milling the material by applying pressure to the material located within the milling gap, between the first and the second rollers of the high-pressure roller mill, to produce the milled product so that particles of the first partial amount of the bulk supply of the material are milled in a packed particle fill in the milling gap while particles of the second partial amount of the bulk supply of the material are milled by contact with both the first and the second rollers; and removing the milled product through the outlet opening.

Description

(1) For increased understanding, further features and advantages of the invention are explained in more detail below by way of exemplary embodiments without the invention being restricted to the exemplary embodiments, in which:

(2) FIG. 1: shows a schematic side view of a high-pressure roller mill according to the invention with bulk material;

(3) FIG. 2: shows a schematic top view of an alternative high-pressure roller mill according to the invention with bulk material;

(4) FIG. 3: shows a schematic representation of a profile according to the invention of a profile roller;

(5) FIG. 4: shows a schematic representation of an alternative profile of a profile roller according to the invention;

(6) FIG. 5: shows a schematic representation of a high-pressure roller mill according to the invention with a separating step and product feed;

(7) FIG. 6: shows an alternative arrangement of a high-pressure roller mill according to the invention with detacher, separating step and product return;

(8) FIG. 7: shows a flow diagram of a method according to the invention using two high-pressure roller mills;

(9) FIG. 8: shows a schematic representation of an enlarged detail of a high-pressure roller mill according to the invention with two profile rollers and bulk material;

(10) FIG. 9: shows a schematic side view of an alternative high-pressure roller mill according to the invention with a level sensor in the feed funnel;

(11) FIG. 10: shows an arrangement of a high-pressure roller mill according to the invention with several separating steps;

(12) FIG. 11: shows a partially exploded view of a perspective representation of a roller according to the invention consisting of a roller body and surface segments;

(13) FIG. 12: shows a section along the longitudinal axis through a roller according to the invention according to FIG. 11;

(14) FIG. 13: shows a front view parallel to the longitudinal axis of the roller according to the invention according to FIG. 11;

(15) FIG. 14: shows a sectioned representation of a roller according to the invention according to FIG. 12 along the sectional plane B;

(16) FIG. 15: shows a perspective representation of a surface segment with the roller surface visible;

(17) FIG. 16: shows a perspective representation of the surface segment according to FIG. 15 from below.

(18) FIG. 1 shows a schematic side view of a high-pressure roller mill 9. A fill 6 includes finer product to be milled 5 as well as coarser product to be milled 7 which is drawn into the milling gap d as a result of the rotation in the direction r of the two rollers 10 and 11.

(19) The roller 10 is mounted so as to be movable in the direction s, i.e. perpendicular to the direction of rotation, as a result of which a milling gap d can be set. The rollers 10 and 11 both have a diameter w of 600 mm and are mounted by means of the bearing 20 to rotate in the direction r. The rollers have a smooth roller surface 19. To avoid oscillations, the bearing 20 has a damping device 26 which is realized as pneumatic damping.

(20) The milling gap d, in the present case, is variable in dependence on the bulk material 6 drawn in, pressure acting in the direction of the milling gap d is set by the rollers 10 and 11 such that the finer material to be milled 5 is milled in the milling gap d by means of a packed particle fill and the coarser material to be milled 7 is comminuted in the milling gap d as a result of direct contact with the rollers 10 and 11. The high-pressure roller mill 9, in this case, has the damping device 26 which is known per se to the person skilled in the art in order to avoid the generation of oscillations of the rollers with respect to one another.

(21) The roller 10 has a circumferential speed of 1 m/s and the roller 11 has a circumferential speed of 1.5 m/s. The speed ratio between the rollers 10 and 11, in this case, is 1.5:1.

(22) In operation, bulk material 6, comprising finer material to be milled 5 and coarser material to be milled 7, is drawn into the high-pressure roller mill 9 as a result of the rollers rotating in the direction r. With reference to the finer material to be milled, a packed particle fill is formed between the two rollers in the milling gap d, which here is set to a value of 1 mm, as a result of which the finer material to be milled is milled.

(23) The coarser material to be milled 7 touches the first roller 10 and the second roller 11 at least in the region of the milling gap d such that said coarser material to be milled is strongly comminuted.

(24) After the milling, the milled product 17 which, for example, can be flour, is then removed from the high-pressure roller mill.

(25) FIG. 2 shows a schematic representation of a top view onto a high-pressure roller mill 9 substantially according to FIG. 1.

(26) From this point on and below, the same references refer to the same components in the figures.

(27) In contrast to the high-pressure roller mill 9 according to FIG. 1, in this case the two rollers are mounted so as to be movable in the direction s. During operation for milling, the rollers are rotatable about the longitudinal axis 21 by means of the bearings (not shown here), both of which include a damping device (not shown here) which is realized as a shock absorber.

(28) In contrast to FIG. 1, the milling gap d here is set in a fixed manner during operation to a value of 1 mm. In the present case, cereal 1 is milled as the coarser material to be milled and semolina 3 as the finer material to be milled.

(29) The roller 10, in the present case, has a circumferential speed of 0.8 m/s and the roller 11 a circumferential speed of 2.4 m/s. Consequently, there is a speed ratio of 3:1.

(30) A further difference to FIG. 1 is that the roller 10 in the present case is realized as a profile roller with a profile which is not shown here.

(31) FIG. 3 shows a schematic representation of a detail of a profile of a roller.

(32) The profile has two completely shown, portionwise indentations 18 with an average depth t of 1.2 mm, the portionwise indentations 18 having a flat face portion 27 perpendicular to the radius of the profile roller. The flat face portion 27 therefore encloses an angle p=90 with the radius of the roller which is indicated as a broken line. A width b of the indentation 18 is 4.3 mm and a spacing k between the portionwise indentations on the roller surface 19 is 0.2 mm. The inner angle a is 135. On both sides of the portionwise indentations 18 with reference to FIG. 3, the roller has further portionwise indentations which are not shown here.

(33) FIG. 4 shows an alternative profile of a profile roller as a detail. The profile roller has an indentation 18 with a width b of 7 mm and a depth t of 1.8 mm. In contrast to FIG. 3, the portionwise indentation 18 is not realized in a symmetrical manner and on the one side in the circumferential direction has an angle a of 120 and on the other side in the circumferential direction an angle a of 140.

(34) FIG. 5 shows in a schematic manner an installation 24 comprising a high-pressure roller mill 9 with two rollers 10 and 11. The rollers 10 and 11, which are both developed as profile rollers with a profile according to FIG. 3, are set to a fixed milling gap d of 0.1 mm. The high-pressure roller mill 9 has a feed opening 15 for the bulk material 6, in this case rice, and an outlet opening 16 for the milled product 17. The milled product 17 is conveyed by means of a conveyor arrangement 25 into a separating step 14 which in this case is realized as a zigzag sifter. In the zigzag sifter, the milled product 17 is separated into finer milled product 12 and coarser milled product 13. Said separation is effected substantially as a result of the physical characteristics of the particles such as, for example, the size, the suspension characteristics and the specific weight or combinations of said characteristics. The coarser milled product 13 is conveyed back into the feed opening 15 of the high-pressure roller mill 9 by means of a return arrangement 23. Finer milled product 12 is removed out of the arrangement 24, in this case as flour.

(35) FIG. 6 shows a further arrangement 24 according to the invention which has a plansifter as the separating step 14 and, in addition, a detacher 22 between the high-pressure roller mill 9 and the separating step 14. The detacher 22 is realized as an impact detacher, as is known to the person skilled in the art, for example from WO 2010/000811 A1. Cocoa is used as the bulk material 6 in this case.

(36) FIG. 7 shows a flow diagram of a method according to the invention. Bulk material 6, in this case sunflower seeds, is supplied to a high-pressure roller mill 9 and is milled in said roller mill. The milled product is supplied to a separating step 14 in which the milled product is separated into finer milled product 12 and coarser milled product 13. The coarser milled product 13 is conveyed back into the high-pressure roller mill 9.

(37) The finer milled product 12, in the present case, is supplied to a further high-pressure roller mill 9, a further separating step 14 being connected downstream of said further high-pressure roller mill. In said further separating step, the milled product from the further high-pressure roller mill 9 is once again separated into finer milled product 12 and coarser milled product 13, the coarser milled product 13 once again being conveyed back into the further high-pressure roller mill 9. The finer milled product 12 can now be processed further as flour.

(38) FIG. 8 shows a schematic representation of details of a high-pressure roller mill 9. The first roller 10 and the second roller 11 are realized in each case with profiles according to FIG. 3. The rollers rotate in the direction of rotation r, the roller 10 having a circumferential speed of 3 m/s and the roller 11 a circumferential speed of 0.5 m/s, i.e. the rollers have a speed ratio of 6:1.

(39) A milling gap d is set in a fixed manner to a value of 0.8 mm, no damping device being provided. The spacing k is 0.3 mm.

(40) The bulk material 6 includes semolina as the finer milled product and hull parts 4 as well as cereal (not shown here) as the coarser milled product, which is milled as described in regard to FIG. 1.

(41) FIG. 9 shows a high-pressure roller mill 9 according to FIG. 1. Material to be milled 8, which forms a fill, is situated in a feed funnel 31. A supply of material to be milled 8 into the feed funnel 31 is not shown here.

(42) The feed funnel 31 includes a level sensor 30 for measuring the level of material to be milled 8 in the feed funnel 31. The circumferential speed of at least one of the rollers 10 or 11 can be set, for example, as a result of the measured level of material to be milled 8 in the feed funnel 31.

(43) If, for example, the level of material to be milled 8 falls below a predetermined value, it is possible to increase the level of material to be milled 8 in the feed funnel 31 by reducing the circumferential speed of at least one of the rollers 10 or 11 since, as a result of said measure, the flow rate through the high-pressure roller mill 9 is reduced, whilst material to be milled 8 continues to be supplied into the feed funnel 31.

(44) By increasing the circumferential speed of at least one of the rollers 10 or 11, the level of material to be milled 8 in the feed funnel 31 can be reduced since, as a result of said measure, the flow rate through the high-pressure roller mill 9 is increased, whilst material to be milled 8 continues to be supplied into the feed funnel 31.

(45) As a result of measuring using the level sensor 30, it is also possible to control the supply of material to be milled 8 into the feed funnel 31 in order to increase or reduce the level in the feed funnel 31 at a constant flow rate through the high-pressure roller mill 9.

(46) A difference to FIG. 1 is that the rollers 10 and 11 are realized as profile rollers with a profile which is not shown in this case.

(47) FIG. 10 shows a further alternative arrangement 24 according to the invention which has a plansifter and a zigzag sifter as separating steps 14.

(48) A fill 6, in this case a mixture of rice and cereals, of material to be milled is situated above a high-pressure roller mill 9. The material to be milled is milled in the high-pressure roller mill 9 into milled product which is then conveyed into the plansifter.

(49) In the plansifter the milled product is separated into a finer milled product 12, an average milled product 29 and a coarser milled product 13. In addition, a further fraction is removed from the plansifter as flour 2. The average milled product 29 is conveyed into a further separating step 14 which, in this case, is realized as a zigzag sifter. In the zigzag sifter the average milled product 29 is separated into finer milled product and coarser milled product 13, the zigzag sifter being set such that the finer milled product essentially includes bran 28. The mass fraction of bran 28 in the material to be milled is within the range of between 1% by weight and 10% by weight and in particular within the range of 3% by weight and 5% by weight with reference to the material to be milled.

(50) The finer milled product 12 and the coarser milled product 13 from the plansifter as well as the coarser milled product 13 from the zigzag sifter are conveyed back into the high-pressure roller mill 9 by means of the return arrangement 23.

(51) FIG. 11 shows a partially exploded view of a perspective representation of a roller 32 according to the invention consisting of a roller body 42 and several surface segments 33. The surface segments 33 have a roller surface 19 on the side remote from the roller body 42.

(52) The roller 32 has a balancing device 36 which is formed by several bores substantially parallel to the longitudinal axis of the roller 32. Balance weights of lead (not shown here) can be inserted into the bores, the bores being closable by means of closure caps 41 once the balance weights have been inserted.

(53) The roller body 42 has a roller groove 37 into which a torque transmitting device 34 which is realized as a bar is insertable. The bar is releasably fastenable in the roller groove 37 by means of a transmitting fastening device 40 realized as screws. The bar, in this case, is realized such that it projects out of the roller groove 37 in the radial direction once it has been inserted into the roller groove 37.

(54) On the side facing the roller body 42, the surface segments 33 have a surface segment groove 38 in which the bar, that is the torque transmitting device 34, is able to engage. In addition, fastening means 35 realized as screws are provided, by means of which the surface segment can be releasably connected to the roller body 42. In the mounted state, the bar engages in the surface segment groove 38, as a result of which reliable torque transmission is ensured during operation from the roller body 42 to the surface segment 33.

(55) FIG. 12 shows a sectioned representation of the roller 32 according to the invention according to FIG. 11 parallel to the longitudinal axis. A segment length o of the surface segments 33 is approximately 400 mm.

(56) FIG. 13 shows a front view of the roller 32 according to the invention according to FIG. 11 parallel to the longitudinal axis 21.

(57) The roller 32 includes 10 surface segments 33. The torque transmitting device 34, which is realized as a bar, is received in the region formed by the surface segment groove and the roller groove.

(58) FIG. 14 shows a sectioned representation of the roller 32 according to the invention parallel to the axis B according to FIG. 12.

(59) The roller 32 includes 10 surface segments 33 which, in each case, cover an angular range m of 36. The surface segments 33 are releasably connected to the roller body 42, a rectangular bar as torque transmitting device 34 being received in the region formed by the roller groove 37 and the surface segment groove 38.

(60) FIG. 15 shows a perspective representation of a surface segment 33 with the roller surface 19. FIG. 16 shows a further perspective from below of the surface segment 33 according to FIG. 15, in which the surface segment groove 38 can be seen.