METHOD FOR OPERATING A MIXING APPARATUS OF A MANUFACTURING PLANT

Abstract

A method for operating a mixing apparatus of a manufacturing plant comprises supplying multiple powdered products to the mixing apparatus. An inlet mass flow rate of the multiple powdered products into the mixing apparatus and a weight of the multiple powdered products in the mixing apparatus are measured. The multiple powdered products in the mixing apparatus are mixed to form a mixed product. The weight of the multiple powdered products in the mixing apparatus and an outlet mass flow rate of the mixed product from the mixing apparatus are predicted based on the measured inlet mass flow of the multiple powdered products. The predicted outlet mass flow rate of the mixed product from the mixing apparatus is corrected based on the measured weight of the multiple powdered products in the mixing apparatus. The mixed product is processed into final products

Claims

1. A method for operating a mixing apparatus of a manufacturing plant in which multiple powdered products is processed into final products, the method comprising: supplying the multiple powdered products to the mixing apparatus; measuring an inlet mass flow rate of the multiple powdered products into the mixing apparatus; measuring a weight of the multiple powdered products in the mixing apparatus; mixing the multiple powdered products in the mixing apparatus to form a mixed product; predicting the weight of the multiple powdered products in the mixing apparatus and an outlet mass flow rate of the mixed product from the mixing apparatus based on the measured inlet mass flow of the multiple powdered products; correcting the predicted outlet mass flow rate of the mixed product from the mixing apparatus based on the measured weight of the multiple powdered products in the mixing apparatus; and processing the mixed product into the final products.

2. The method according to claim 1, wherein the predicting of the weight of the multiple powdered products in the mixing apparatus and of the outlet mass flow rate of the multiple powdered products from the mixing apparatus take place in real time

3. The method according to claim 2, wherein the correcting of the prediction of the outlet mass flow rate of the multiple powdered products from the mixing apparatus take place in real time.

4. The method according to claim 1, wherein the correcting of the prediction of the outlet mass flow rate of the multiple powdered products from the mixing apparatus uses a least squares method.

5. The method according to claim 1, wherein a Kalman filter method is used in the predicting of the weight of the multiple powdered products in the mixing apparatus, the predicting of the outlet mass flow rate of the multiple powdered products from the mixing apparatus, and the correcting of the prediction of the outlet mass flow rate of the multiple powdered products from the mixing apparatus.

6. The method according to claim 1, wherein the multiple powdered products are supplied to the mixing apparatus via multiple product inlets.

7. The method according to claim 6, wherein the multiple product inlets each comprise at least one dosing apparatus.

8. The method according to claim 7, wherein the at least one dosing apparatus a loss-in-weight apparatus.

9. The method according to claim 1, wherein the manufacturing plant is configured for manufacturing tablets, and wherein the mixed product is pressed into tablets in a tablet press.

10. The method according to claim 1, wherein the manufacturing plant is configured for manufacturing capsules, and wherein the mixed product is filled into capsules in a capsule-filling machine.

11. The method according to claim 1, wherein progression of the powdered products and mixed product through at least one of: (1) the mixing apparatus; and (2) the manufacturing plant is tracked based on the measured inlet mass flow rate of the multiple powdered products into the mixing apparatus, the measured weight of the multiple powdered products in the mixing apparatus, and the corrected prediction of the outlet mass flow rate of the mixed product from the mixing apparatus.

12. The method according to claim 11, further comprising: dividing the multiple powdered products entering the mixing apparatus into mass units based on the measured inlet mass flow rate of the multiple powdered products into the mixing apparatus; and tracking progression of the mass units through the mixing apparatus using the corrected prediction of the outlet mass flow rate of the mixed product from the mixing apparatus.

13. The method according to claim 12, further comprising: dividing the supplied multiple powdered products into mass units based on measurement data from inlet mass sensors arranged at the multiple product inlets; and tracking progression of the mass units through the manufacturing plant using the measurement data from at least one other mass sensor at a different position from the multiple product inlets.

14. The method according to claim 13, wherein tracking the progression of the mass units further uses measurement data from another mass sensor arranged at a tablet outlet of a tablet press.

15. The method according to claim 12, wherein masses of the mass units are equal.

16. The method according to claim 12, wherein masses of the mass units are in a range from 1 g to 20 g.

17. The method according to claim 1, wherein the manufacturing plant is configured for continuously processing the multiple powdered products into the final products.

18. The method according to claim 1, wherein the manufacturing plant is a containment plant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] An exemplary embodiment of the invention is explained below in greater detail with reference to figures, wherein:

[0037] FIG. 1 illustrates a partial schematic depiction of an embodiment of a plant used in an embodiment of a method for manufacturing tablets with a tablet press; and

[0038] FIG. 2 illustrates is a schematic representation of an embodiment of the method for manufacturing tablets with a tablet press.

[0039] The same reference numbers refer to the same objects in the figures unless indicated otherwise.

DETAILED DESCRIPTION OF THE INVENTION

[0040] The plant shown in FIG. 1 is a plant or system for manufacturing tablets in which powdered product is pressed into tablets. The plant accordingly comprises a rotary press, in particular a rotary tablet press, arranged in a housing 11, with a rotor that is rotationally driven by a rotary drive and that has a die plate 10 comprising a plurality of receiving means 12. The receiving means 12 may for example be in the form of holes in the die plate 10. Furthermore, the rotor comprises a plurality of upper punches 14 and lower punches 16 that rotate synchronously with the die plate 10. The upper punches 14 are axially guided in an upper punch guide 18 and the lower punches 16 are axially guided in a lower punch guide 20. The axial movement of the upper punches 14 and lower punches 16 during the rotation of the rotor is controlled by upper control cam elements 22 and lower control cam elements 24. The rotary press further comprises a filling apparatus 26, which comprises a filling reservoir 28 and a filling chamber 30, which are connected via a filling pipe 32. In this way, the powdered filling material in the present example passes under the force of gravity from the filling reservoir 28 via the filling pipe 32 into the filling chamber 30, and passes therefrom via a filling opening provided in the bottom side of the filling chamber 30 into the receiving means 12 of the die plate 10, again under the force of gravity.

[0041] The rotary press further comprises a pressing apparatus 34. The pressing apparatus 34 has a pre-pressing apparatus having an upper pre-pressing roller 36 and a lower pre-pressing roller 38, as well as a main pressing apparatus having an upper main pressing roller 40 and a lower main pressing roller 42. Furthermore, the rotary press comprises an ejection apparatus 44 and a scraping apparatus 46 having a scraping element, which supplies the tablets 48 produced in the rotary press to a discharge apparatus 50 for discharging the tablets from the rotary press. The scraping apparatus 46 may for example comprise a preferably crescent-shaped scraping element, which scrapes tablets 48 conveyed by means of the lower punches 16 onto the top side of the die plate 10 off the die plate 10 in the region of the ejection apparatus 44 and supplies them to the discharge apparatus 50.

[0042] The housing 11 may be at a positive or negative pressure with respect to the surroundings of the housing 11. Moreover, the housing 11 may be sealed with respect to the surroundings. The rotary press may be a so-called containment press.

[0043] It is expressly noted that the rotary press shown in FIG. 1 and having the properties detailed above is merely exemplary. In principle, any other tablet press is suitable for the invention. Indeed, any other type of production machine in which powdered product is processed into final products is, in principle, also suitable for the invention, for example a capsule-filling machine, in which powdered product is filled into capsules.

[0044] In the example shown, the plant further comprises two product inlets 52, 54 for two different products, for example an active pharmaceutical ingredient and an excipient, to be supplied to the tablet press in order to be pressed into tablets 48. The product inlets 52, 54 may for example comprise dosing apparatuses, in particular loss-in-weight dosing apparatuses. The products supplied arrive from the product inlets 52, 54 at a mixing apparatus 56 of the plant, in which the products are mixed to form a product mixture to be pressed. The mixing apparatus 56 may for example comprise a mixing screw. In the example shown, the mixing apparatus 56 is oriented horizontally. In particular, an axis of rotation of a mixing screw of the mixing apparatus 56 extends in a horizontal direction. The housing of the mixing apparatus 56 is also oriented horizontally. The mixed product leaving the mixing apparatus 56 is supplied via a supply line 58 to the filling reservoir 28 of the filling apparatus 26. The plant additionally comprises an evaluation and control apparatus 60 for controlling the operation of the plant and for carrying out the method according to the invention on the basis of evaluation algorithms stored in the evaluation and control apparatus 60. One or more sensors 100 may be positioned throughout the manufacturing plant or manufacturing line. The sensors 100 may be weight sensors, mas flow sensors, load cells or other similar sensors. The product inlets 52, 54, the filling apparatus 26 and the tablet press, in particular a tablet outlet 44 of the tablet press, may each comprise at least one weight sensor, by means of which the weight of product guided through the plant or tablets discharged from the plant can be determined directly or indirectly, respectively. The mixing apparatus 56 also comprises, at the inlets thereof, mass flow rate sensors, by means of which the product inlet mass flow rate of the product flowing into the mixing apparatus 56 from the product inlets 52, 54 is measured. Moreover, the mixing apparatus 56 comprises a load cell, by means of which the weight of the product located in the mixing apparatus 56 is measured. The evaluation and control apparatus 60 is connected to the mass flow rate sensors for measuring the product inlet mass flow rate, to the load cell for measuring the weight of the product located in the mixing apparatus 56 and to the mass sensors and, if applicable, to other sensors of the plant. In particular, it receives measurement data from the sensors and uses said data as the basis for the control and evaluation. For this purpose, the evaluation and control apparatus 60 may be connected to all components of the plant via corresponding connection lines.

[0045] The method according to the invention will be explained in greater detail below with reference to the diagram in FIG. 2. In FIG. 2, {dot over (m)}.sub.i denotes the product inlet mass flow rate out of the product inlets 52, 54 measured by the mass sensors of the mixing apparatus 56. This measured value is applied to the evaluation and control apparatus 60, as shown by the arrow 62 in FIG. 2. Based on the measured value for the product inlet mass flow rate {dot over (m)}.sub.i the evaluation and control apparatus 60 calculates a predicted value for the weight of the product located in the mixing apparatus 56 using a mathematical model. This value is denoted by in FIG. 2. Moreover, the evaluation and control apparatus 60 calculates a predicted value for the product outlet mass flow rate of the mixed product out of the mixing apparatus 56 based on the measured product inlet mass flow rate {dot over (m)}.sub.i. This value is denoted by .

[0046] As illustrated by the arrow 64 in FIG. 2, the predicted value for the weight of the product located in the mixing apparatus 56 is applied to a comparison apparatus 66, which may also be part of the evaluation and control apparatus 60. The value for the weight of the product located in the mixing apparatus 56 measured by the load cell is also applied to the comparison apparatus 66, as shown by the arrow 68. This measured value is denoted by m.sub.p. If the comparison apparatus 66 detects a difference between the measured value m.sub.p and the predicted value , this is provided to the evaluation and control apparatus 60 as a calculation error e.sub.p, as illustrated by the arrow 70. Based on this calculation error e.sub.p, the evaluation and control apparatus 60 corrects the calculated prediction value for the product outlet mass flow rate according to the mathematical model. This method, described with reference to FIG. 2, may run permanently during operation of the mixing apparatus or plant.

[0047] The above-described prediction of the weight of the product located in the mixing apparatus and of the product outlet mass flow rate out of the mixing apparatus 56 as well as the correction of the prediction of the product outlet mass flow rate are preferably carried out using a KALMAN filter method. By virtue of the method according to the invention, product tracking in the plant and in particular the mixing apparatus 56 can be carried out in a reliable manner and also outside of stationary states, in particular in transient states.

[0048] For the product tracking, it is also possible for the product fed into the plant via the product inlets 52, 54 to be divided into mass units of equal size based on measurement data from inlet mass sensors, for example mass or weight sensors of loss-in-weight dosing apparatuses, arranged at the product inlets 52, 54. In the dispersion zone created by the mixing apparatus 56, new mass units that contain product portions in each case from two mass units of the two product inlets 52, 54 in accordance with the known supply ratio into the mixing apparatus 56 are then formed in the evaluation and control apparatus 60 from the mass units of the two product inlets 52, 54. The mixing of the constituents of the mass units in the dispersion zone created by the mixing apparatus 56 is taken into consideration in accordance with the also known, for example empirically determined, mixing ratio of the mixing apparatus 56. Based on the product outlet mass flow rate predicted and, if applicable, corrected using the method according to the invention, the mass units can accordingly be tracked further at the outlet of the mixing apparatus 56. The progress of these mass units through the plant, in particular to the tablet press 62, is tracked further for example using measurement data from a mass sensor arranged in the filling apparatus 26 of the tablet press. The ejected tablets 48 can be assigned to specific mass units previously fed to the plant via the product inlets 52, 54 and thus to the corresponding product batch by means of another mass sensor that is for example arranged at the outlet of the tablet press and that counts the ejected tablets and, if applicable, also measures the weight thereof. If, for example, one or more mass units are detected to be defective during the course of their progress through the plant by sensors of the plant, it is therefore possible in this manner to reliably identify the tablets manufactured from these mass units such that these tablets can be discarded. On account of the method according to the invention, this type of mass-based product tracking can be carried out in a reliable manner at any time, even and especially in transient states.

[0049] The mass units may all have the same mass. The mass of the mass units may preferably be less than 20 g, more preferably less than 10 g, for example approximately 1 g. The plant is in particular a plant for manufacturing tablets continuously, and it may be a containment plant.

LIST OF REFERENCE SIGNS

[0050] 10 Die plate [0051] 11 Housing [0052] 12 Receiving means [0053] 14 Upper punches [0054] 16 Lower punches [0055] 18 Upper punch guide [0056] 20 Lower punch guide [0057] 22 Upper control cam elements [0058] 24 Lower control cam elements [0059] 26 Filling apparatus [0060] 28 Filling reservoir [0061] 30 Filling chamber [0062] 32 Filling pipe [0063] 34 Pressing apparatus [0064] 36 Upper pre-pressing roller [0065] 38 Lower pre-pressing roller [0066] 40 Upper main pressing roller [0067] 42 Lower main pressing roller [0068] 44 Ejection apparatus [0069] 46 Scraping apparatus [0070] 48 Tablets [0071] 50 Discharge apparatus [0072] 52 Product inlet [0073] 54 Product inlet [0074] 56 Mixing apparatus [0075] 58 Supply line [0076] 60 Evaluation and control apparatus [0077] 62 Arrow [0078] 64 Arrow [0079] 66 Comparison apparatus [0080] 68 Arrow [0081] 70 Arrow