Device and method for comminuting particles in liquid material

Abstract

The invention relates to a device (1) for comminuting particles in a liquid material, in particular a powder or a semi-liquid for producing a chocolate mass. Said device (1) comprises at least one pair of rollers (2, 3), for which at least one process parameter, in particular the roller contact pressure and/or the rotational speed of one of the rollers (2, 3) can be adjusted. The invention also relates to a device (1) comprising a filling level meter (11) for measuring the height of the filling level (5) of the liquid material in the roller gap or in a roller trough (4) arranged upstream of the rollers. A control unit (11) modifies at least one process parameter in accordance with the measured height of the filling level (5) of the liquid material in the roller gap or in the roller trough (4). The invention also relates to a method for comminuting particles in a liquid material and to a method for calibrating a control unit (10).

Claims

1. A method for comminution of particles in a flowable material for production of a chocolate mass, the particles being sugar crystals, cocoa nibs, milk powder or combinations thereof, and the method comprising: comminuting the particles between at least one pair of rollers, for which at least a rate of rotation of at least one roller of the pair of rollers can be set, and measuring a current filling level of the flowable material in a roller nip or in a roller trough preceding a pair of rollers, wherein at least the rate of rotation of at least one roller of the pair of rollers is varied as a function of the measured filling level of the flowable material, and at least one of the filling level of the flowable material in the roller nip or in the roller trough and variations in the filling level are continuously determined contactlessly by a filling level meter; and the filling level meter has a camera directed at the roller nip and an image evaluation unit which determines the filling level based on a camera image.

2. The method as claimed in claim 1, wherein the flowable material is delivered continuously to the roller nip or to the roller trough.

3. The method as claimed in claim 1, wherein the filling level is measured continuously.

4. The method as claimed in claim 1, wherein, first, a desired value for the filling level is fixed, and at least one process parameter is varied automatically in such a way that the measured filling level corresponds to the specified desired value.

5. The method as claimed in claim 4, wherein the at least one process parameter is varied automatically by a regulating unit.

6. The method as claimed in claim 4, wherein, first, a calibration step takes place, in which a value of the at least one process parameter is fixed, at which at least one of a specific degree of comminution of the particles in a grinding stock is achieved and at which a desired value or desired value range for the filling level is determined.

7. A method for comminution of particles in a flowable material for production of a chocolate mass, the particles being sugar crystals, cocoa nibs, milk powder or combination thereof, and the method comprising: comminuting the particles between at least one pair of rollers, for which at least a rate of rotation of at least one roller of the pair of rollers can be set, and measuring a current filling level of the flowable material in a roller nip or in a roller trough preceding a pair of rollers, wherein the rate of rotation of at least one roller of the pair of rollers is varied as a function of the measured filling level of the flowable material, and the current filling level of the flowable material in the roller nip or in the roller trough is continuously measured contactlessly by one of a filling level meter; and the filling level meter has a camera directed at the roller nip and an image evaluation unit which determines the filling level based on a camera image.

8. The method as claimed in claim 1, wherein the flowable material is delivered into the roller nip or into the roller trough by a feed arrangement, which is arranged upstream of the pair of rollers in the material flow direction.

9. The method as claimed in claim 1, wherein at least one roller is configured as a camberless roller.

10. A method for comminution of one of sugar crystals, cocoa nibs and milk powder, in a liquid flowable material, to produce a chocolate mass, and the method comprising: comminuting one of sugar crystals, cocoa nibs and milk powder between at least one pair of rollers, for which at least a rate of rotation of at least one roller of the pair of rollers can be set, and measuring a current filling level of the liquid flowable material in a roller nip or in a roller trough preceding a pair of rollers, wherein the at least the rate of rotation of at least one roller of the pair of rollers is varied as a function of the measured filling level of the liquid flowable material, and at least one of the filling level of the liquid flowable material in the roller nip or in the roller trough and variations in the filling level are continuously determined contactlessly by a filling level meter viewing the roller nip or the roller trough; and the filling level meter has a camera directed at the roller nip and an image evaluation unit which determines the filling level based on a camera image.

Description

(1) Further details and embodiments of the present invention may be gathered from the following description of the figures and examples. In the figures:

(2) FIG. 1 shows a diagrammatic illustration of a first example of a device according to the invention;

(3) FIG. 2 shows a diagrammatic illustration of a second example of a device according to the invention;

(4) FIG. 3 shows a diagrammatic illustration of a third example of a device according to the invention;

(5) FIG. 4 shows a diagrammatic illustration of a fourth example of a device according to the invention;

(6) FIG. 5 shows a diagrammatic illustration of a fifth example of a device according to the invention.

(7) FIG. 1 shows a diagrammatic illustration of a device 1 according to the invention. The device 1 has at least two rollers 2, 3 arranged as a pair of rollers. Between the rollers 2, 3 there is a roller nip 14. Each of the two rollers 2, 3 of the pair of rollers is driven by a separate motor 6, 7 having a controlled rotational speed. The pressure force between the rollers 2, 3 is set via a pressure regulator 8. Upstream of the rollers 2, 3 a roller trough 4 is arranged, to which flowable material 13 is delivered by a feed arrangement 9. The filling level 5 of the flowable material 13 in the roller trough 4 is measured by a filling level meter 11. The measuring direction of the filling level meter 11 is such that the filling level 5 of the flowable material in the roller trough 4 can be measured. The measured filling level is transmitted to a regulating unit 10. On the basis of the measured filling level 5, at least one process parameter is varied by the regulating unit 10. In particular, the rate of rotation of at least one roller 2, 3 is varied via the rotational speed of the accompanying motor 6, 7. Alternatively, the pressure force of the rollers 2, 3 may be varied by the pressure regulator 8.

EXAMPLE 1

(8) A constant pressure force of the rollers of 28 bar and a constant throughput of 1200 kg/h give rise in an exemplary material to a particle size of 80 m. If the properties of the flowable material change during the method, the product draw-in of the material between the rollers and therefore the throughput are also varied. In the example, in the case of a constant delivery of material into the roller nips or into the roller trough, the filling level is varied in such a way that it decreases. This variation is recorded by the filling level meter, whereupon a corresponding variation in the pressure force, for example an increase in pressure in steps of 0.5 bar, takes place by means of the regulating unit. This variation continues until the desired value of the filling level in the roller nip or in the roller trough is reached again. In the event of major variations in throughput, the rotational speed of the rollers is additionally varied, for example by 30 to 100 revolutions per minute.

EXAMPLE 2

(9) When non-cambered rollers with elastic jacket intermediate material are used for generating small particles, for example 40 m, a high pressure force is required, for example 35 bar, which results in a correspondingly lower throughput of flowable material. Consequently, with a constantly high pressure, the throughput can be increased by increasing the roller rotational speeds.

EXAMPLE 3

(10) With a set starting pressure in the roller nip of 28 bar and with roller rates of rotation of 50 rev/min for a first roller and of 100 rev/min for the second roller of the pair of rollers, grinding stock is ground. This results in a throughput of 800 kg/h with a degree of comminution of the particles located in the grinding stock of 30 m.

(11) If the pressure in the roller nip is increased to 35 bar, the throughput is reduced to 600 kg/h, the degree of comminution of the particles falling to 20 m.

(12) An increase in the roller rates of rotation to 75 rev/min for the first roller and to 150 rev/min for the second roller increases the throughput to 1000 kg/h, the degree of comminution of the particles rising again to 30 m.

(13) Furthermore, by further increasing the pressure to 45 bar and by increasing the roller rates of rotation to 75 rev/min for the first roller and to 150 rev/min for the second roller, the throughput can be set at the original 800 kg/h, with a degree of comminution of the particles of 20 m.

(14) A continuous method is achieved when the filling level of the grinding stock in the roller nip or in a roller trough preceding the at least one pair of rollers remains constant. In this state, the process parameters are set in such a way that the delivered quantity of grinding stock corresponds to the discharged quantity, that is to say a preselected throughput is achieved.

(15) FIG. 2 shows a diagrammatic illustration of a second example of a device 101 according to the invention.

(16) A roller 102 forms with a fixed wall 115 a roller nip 114. A process parameter of the roller 102, for example the roller pressure force or the rate of rotation, can be regulated as a function of the filling level 105 of the flowable mass in the roller nip 114.

(17) FIG. 3 shows a diagrammatic illustration of a third example of a device 201 according to the invention.

(18) Two rollers 202, 203 of identical size form a first pair of rollers 220 for which a process parameter, for example the roller pressure force or the rate of rotation of at least one of the rollers 202, 203, can be set.

(19) The rollers 202, 203 are preceded by a further roller 216 of smaller diameter, which serves as an applicator roller and with one of the rollers 203 forms a further pair of rollers. This encloses a roller nip 217 in which initial stress upon the flowable material occurs.

(20) A three-high rolling mill with two pairs of rollers is thus obtained.

(21) The applicator roller 216 forms with a trough wall 218 a roller trough 204.

(22) A process parameter of the pair of rollers 220, for example the roller pressure force or the rate of rotation of at least one roller 202, 203, can be regulated as a function of the filling level 205 of the flowable mass in the roller trough 204.

(23) FIG. 4 shows a diagrammatic illustration of a fourth example of a device 301 according to the invention in the form of a further example of a three-high rolling mill.

(24) A roller 316 having a smaller diameter follows a pair of rollers 320 with two larger rollers 302, 303.

(25) A process parameter of the pair of rollers 320, for example the roller pressure force or the rate of rotation of at least one roller 302, 303, or of the second pair of rollers 321, for example the roller pressure force or the rate of rotation of at least one roller 303, 316, can be regulated as a function of the filling level 305 of the flowable mass 313 in the roller nip 314 of the first pair of rollers 320.

(26) FIG. 5 shows a diagrammatic illustration of a fifth example of a device 401 according to the invention in the form of a further example of a three-high rolling mill.

(27) The three-high rolling mill likewise has two pairs of rollers 420, 421.

(28) A process parameter of the pair of rollers 420, for example the roller pressure force or the rate of rotation of at least one roller 402, 403, or of the second pair of rollers 421, for example the roller pressure force or the rate of rotation of at least one roller 403, 416, can be regulated as a function of the filling level 405 of the flowable mass 413 in the roller nip 414 of the first pair of rollers 420.

(29) In addition, a fineness meter, not illustrated explicitly in the figure, may be provided, which determines the fineness of the product located on the discharge roller 416. If the fineness has not yet reached a fixed desired value, the product can be delivered to the first roller nip 414 again.