Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G13/00—Weighing apparatus with automatic feed or discharge for weighing-out batches of material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/74—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant
  • B29B7/78—Mixing; Kneading using other mixers or combinations of mixers, e.g. of dissimilar mixers ; Plant by gravity, e.g. falling particle mixers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B1/00—Packaging fluent solid material, e.g. powders, granular or loose fibrous material, loose masses of small articles, in individual containers or receptacles, e.g. bags, sacks, boxes, cartons, cans, or jars
  • B65B1/04—Methods of, or means for, filling the material into the containers or receptacles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
  • B01F21/00—Dissolving
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/02—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type
  • B29B7/22—Component parts, details or accessories; Auxiliary operations
  • B29B7/24—Component parts, details or accessories; Auxiliary operations for feeding
  • B29B7/242—Component parts, details or accessories; Auxiliary operations for feeding in measured doses
  • B29B7/244—Component parts, details or accessories; Auxiliary operations for feeding in measured doses of several materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/02—Mixing; Kneading non-continuous, with mechanical mixing or kneading devices, i.e. batch type
  • B29B7/22—Component parts, details or accessories; Auxiliary operations
  • B29B7/28—Component parts, details or accessories; Auxiliary operations for measuring, controlling or regulating, e.g. viscosity control
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
  • B29B7/58—Component parts, details or accessories; Auxiliary operations
  • B29B7/60—Component parts, details or accessories; Auxiliary operations for feeding, e.g. end guides for the incoming material
  • B29B7/603—Component parts, details or accessories; Auxiliary operations for feeding, e.g. end guides for the incoming material in measured doses, e.g. proportioning of several materials
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B7/00—Mixing; Kneading
  • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
  • B29B7/58—Component parts, details or accessories; Auxiliary operations
  • B29B7/72—Measuring, controlling or regulating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65B—MACHINES, APPARATUS OR DEVICES FOR, OR METHODS OF, PACKAGING ARTICLES OR MATERIALS; UNPACKING
  • B65B1/00—Packaging fluent solid material, e.g. powders, granular or loose fibrous material, loose masses of small articles, in individual containers or receptacles, e.g. bags, sacks, boxes, cartons, cans, or jars
  • B65B1/30—Devices or methods for controlling or determining the quantity or quality or the material fed or filled
  • B65B1/32—Devices or methods for controlling or determining the quantity or quality or the material fed or filled by weighing
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G11/00—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers
  • G01G11/08—Apparatus for weighing a continuous stream of material during flow; Conveyor belt weighers having means for controlling the rate of feed or discharge
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G13/00—Weighing apparatus with automatic feed or discharge for weighing-out batches of material
  • G01G13/003—Details; specially adapted accessories
  • G01G13/006—Container supply or discharge mechanism
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G17/00—Apparatus for or methods of weighing material of special form or property
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
  • G01G19/387—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for combinatorial weighing, i.e. selecting a combination of articles whose total weight or number is closest to a desired value
  • G01G19/393—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups for combinatorial weighing, i.e. selecting a combination of articles whose total weight or number is closest to a desired value using two or more weighing units
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
  • B30B11/02—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space
  • B30B11/08—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using a ram exerting pressure on the material in a moulding space co-operating with moulds carried by a turntable
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B30—PRESSES
  • B30B—PRESSES IN GENERAL
  • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
  • B30B15/30—Feeding material to presses
  • B30B15/302—Feeding material in particulate or plastic state to moulding presses

Definitions

• Feeder unit a feeder module comprising a plurality of feeder units, and method for discharging a constant mass flow of one or more powders into a receiving container
• the present invention relates to a feeder unit comprising a storage hopper, a weighing cell, a conveyer, and a discharge end, the storage hopper being adapted to be connected to a refilling system, and the discharge end to a receiving container, a working space being defined by the arithmetic product of dead weight of the feeder unit and the refilling interval.
• the invention furthermore relates to a feeder module comprising a plurality of feeder units, and a method for discharging a constant mass flow of one or more powders into a receiving container.
• Typical manufacturing processes hitherto employed within the pharmaceutical field are of a batch nature. Batch manufacturing processes have a number of advantages and provide satisfactory results within many areas.
• the level of quality of monitoring and control attainable by a batch proc- ess is often not sufficient, i.a. due to the fact that settings are fixed.
• a relatively large buffer volume is required, entailing undesired back- mixing of the material stream.
• manufacturers' and customers' focus of interest has shifted to continuous processes, in which settings may be varied and are allowed to change within a design space.
• Some examples of continuous processes have been devised in the prior art, for instance in EP 0 275 834 A1 , in which two or more ingredients are fed into the process line at various feed or inlet points, and the ingredients are mixed, dried and subsequently compacted in a conventional tabletting machine.
• the process line includes a first mixing unit, a drying unit, a sizing unit and a second mixing unit.
• the output corresponds to the aggregated input of ingredi- ents at the feed or inlet points, i.e. all of the material is fed to the manufacturing machine in a continuous flow and at a constant rate. Due to a variety of factors, this is not feasible in practice. First, it is under any circumstances almost impossible to adjust the output from the mixing and drying units to pro- vide a just-in-time supply of material to the tabletting machine. Second, the continuous production of tablets of a desired high level of quality requires careful monitoring, controlling and adjustment of process parameters in order to avoid a large rejection number from the tabletting machine. This may lead to accumulation of material along the process line awaiting adjustment of cer- tain process parameters. In turn, this inevitably necessitates the use of intermediate buffer vessels in order to store material upstream of the tablet press.
• WO 2010/128359 (GEA Pharma Systems), a contained module being able to operate by a fully continuous process for the production of tablets is devised.
• all units of the tabletting process may be contained, thus reducing the risk of operator exposure and facilitating operation of the tablet press, as all preparations of the material stream fed to the tablet press are carried out in a contained and controlled manner.
• the term "contained" is defined by its level of containment according to suitable measurements, and is defined as at least dust-tight.
• mixing unit refers to a unit operation generally capable of mixing or otherwise processing one, two or more com- ponents into a desired form.
• the mixing unit may thus also be capable of modifying the physical form of dry component(s) processed in the mixing unit, e.g. a feed stream of powder(s) may be converted to a granulate comprising the component(s).
• the mixing unit may be a granulator for making a granulate from dry powders, such as a granulator to which a granulating liquid is added, or a roller compactor.
• the mixing unit may include such equipment as a dryer, a dry blender, a continuous dry blender or the like. Dispensing or dosing the component(s) to the mixing unit, or to a receiving container upstream of the mixing unit, most often takes place from storage hoppers connected to feeders which in turn supply the mixing unit or receiving container with the desired amount of powder(s) or other compo- nent(s). Feeding of powders is carried out by means of screw conveyors according to one of two main solutions: volumetric feeding or gravimetric feeding.
• EP 290 999 B1 One example of prior art concerned with achieving an increased accuracy when feeding powders is EP 290 999 B1 , in which powders are fed from storage hoppers to a weighing hopper and further to a mixing or preparation container.
• a feeder unit of the kind mentioned in the introduction which is furthermore characterized in that the working space (ws) is below 0.2 kgh.
• the feeder unit is able to dispense a very accurately measured amount of material into a receiving container. Relative to feeder units having a higher dead weight and usually a lower refill interval, it is pos- sible to obtain a higher accuracy in the measurement because of the lower dead weight of the feeder unit. Loss in-weight-feeders known in the art typically weigh up 20-100 kg. Consequently, a higher inaccuracy is present because the loss in weight is so small, typically 0.05-0.1 g, and the weight of the feeder unit is included in weight measurement.
• the working space (ws) is below 0.1 kgh.
• the dead weight of the feeder unit lies in the range 1 to 8 kg, preferably 1 to 6 kg, more preferably 1 to 3 kg.
• the storage hopper may have a predefined volume to define a capacity of the storage hopper below 10 liters, preferably below 5 liters, most preferably below 3 liters.
• the maximum net weight of powder in the storage hopper may lie in the interval 50 g to 5000 g the working space may be below 0.2 kgh, preferably below 0.1 kgh, most preferred below 0.05 kgh.
• the feeder unit may comprise a refilling valve connected to the storage hopper and a level or weight indicator above the refilling valve for controlled predosing of a refill amount.
• a controller adapted to store a conveying parameter together with a level or a weight may be provided.
• the weighing cell may be any weighing cell fulfilling the demands to accuracy on that point and preferably, the weighing cell is with Electro Magnetic Force Restoration (EMFR).
• EMFR Electro Magnetic Force Restoration
• each feeding unit In order to allow for detachment of parts of each feeding unit relative to other parts, it is advantageous that the storage hopper, the conveyer and the discharge end of each feeder unit are releasably connected to the weighing cell.
• the powder may in principle be transported or pumped from the storage hopper to the receiving container in any suitable manner.
• the conveyer is a twin screw conveyor.
• At least one, preferably both, of the screws of the twin screw conveyor has a variable pitch along its length underneath the storage hopper.
• At least one, preferably both, of the screws has a variable diameter along its length underneath the storage hopper.
• the variable diameter assures that the whole length of at least one screw, or of both screws, under the hopper is evenly loaded and hereby creating an even transport volume over the section of the hopper.
• the feeder unit comprises a controller for processing weight signals and compensate for external forces.
• the feeder unit may further comprise a sensor for sensing material variations.
• the storage hopper, the conveyer, and the discharge end of the feeder unit are contained and isolated from the weighing cell.
• a feeder module comprising a plurality of feeder units, wherein five to eight feeder units are arranged in a spokes- like configuration, each feeder unit extending radially outwards from an imaginary inner circle defined at the discharge end adapted to face the com- mon receiving container to an imaginary outer circle defined by radially opposite end of each feeder unit, the feeder units being positioned substantially on radii extending from the imaginary inner circle.
• the feeder unit ac- cording to the invention may be utilised independently, it may thus form part of a feeder module which also benefits from the greater accuracy obtained.
• a method for discharging a constant mass flow of one or more powders into a receiving container is pro- vided, said method being suitable for being operated in a feeder unit of the first aspect, said method comprising the steps of:
• a feeder unit with a storage hopper, a weighing cell, a conveyer, and a discharge end
• the refilling valve dispenses the same amount of powder into the storage hopper
• the conveyer is operated according to the data collected during previous refills.
• Fig. 1 shows a perspective view of an embodiment of a feeder module of the invention
• Fig. 2 shows a plan view of the feeder module of Fig. 1 ;
• Fig. 2a shows a schematic overview corresponding to Fig. 2, in an embodiment comprising eight feeder units;
• Fig. 2b shows a schematic overview corresponding to Fig. 2a, of another embodiment comprising seven feeder units;
• Fig. 2c shows a schematic overview corresponding to Fig. 2a, of fur- ther embodiment comprising six feeder units;
• Fig. 2d shows a schematic overview corresponding to Fig. 2a, of further embodiment comprising five feeder units;
• Fig. 3 shows a sectional view of the feeder module of Fig. 1 ;
• Fig. 4 shows a detail cross section of the receiving hopper or receiv- ing container
• Figs 5 and 6 show a plan view of a feeder module of another embodiment in two different conditions
• Fig. 7 shows a perspective view of a detail of an embodiment of a feeder module and containment of powder contacting powder pump accord- ing to the invention
• Figs 8a-c show a side view of a detail of a pre-feeder element of a feeder module according to the invention
• Figs 9a-9c show a perspective view of an embodiment of a feeder module, a view from above of a feeder unit and a more detailed perspective view of an embodiment of a feeder module according to the invention.
• Figs 10 and 1 1 show plan views of a detail of two different embodiments of a feeder module according to the invention.
• a feeder module generally designated 1 is shown.
• the feeder module 1 comprises a plurality of feeder units 2.
• Each feeder unit 2 comprises a feeder part 20 and a weighing cell.
• a pre-feeder element 40 is attached to the feeder part 20.
• the feeder unit 2 according to the invention may also be used independently, as a single unit.
• the feeder module comprises five feeder units 2 and the diameter of the imaginary inner circle is 42-100 mm for a twin screw discharge tube (WDis) of 24 to 45 mm and a lateral clearance (CL) in between two twin screw discharge tubes of 1 to 10 mm, see Fig. 2d.
• WDis twin screw discharge tube
• CL lateral clearance
• the feeder module may comprise six feeder units and the diameter of the imaginary inner circle is 50-120 mm for a twin screw discharge tube of 24 to 45 mm and a lateral clearance (CL) in between two twin screw discharge tubes of 1 to 10 mm. See Fig. 2c.
• the feeder module comprises seven feeder units and the diameter of the imaginary inner circle is 57-140 mm for a twin screw discharge tube of 24 to 45mm and a lateral clearance (CL) in between two twin screw discharge tubes of 1 to 10 mm, see Fig. 2b.
• the feeder module comprises eight feeder units and the diameter of the imaginary inner circle is 65- 150 mm for a twin screw discharge tube of 24 to 45 mm and a lateral clearance in between two twin screw discharge tubes of 1 to 10 mm, see Fig. 2a.
• each feeder unit 2 includes a storage hopper 21 to contain material to be processed, a conveyer 22, a discharge end 23, and a weighing cell 24.
• the conveyer 22 has the function of transporting the material from the storage hopper 21 to discharge the material into a receiving container in a manner to be described in further detail below. Furthermore, it emerges from these Figures that the feeder units 2 are arranged in a single level to discharge into a common receiving container 3.
• the feeder units 2 are dis- tributed substantially evenly over 360° in the same level, i.e. on substantially the same horizontal plane.
• the feeder units 2 are arranged in a spokes- like configuration, each feeder unit 2 extending radially outwards from an imaginary inner circle 31 defined at the discharge end 23 facing the common receiving container 3 to an imaginary outer circle defined by radially opposite end of each feeder unit.
• the feeder units 2 are positioned substantially on radii extending from the imaginary inner circle.
• the smallest possible dimension of the imaginary inner circle 31 depends on the number of feeder units 2 and of the physical dimensions of the individual feeder units 2. Typical values in embodiments comprising five feeder units, possibly distributed substantially evenly, are a diameter of the imaginary inner circle of 42-100 mm. In an embodiment comprising six feeder units, possibly distributed substantially evenly, the diameter of the imaginary inner circle is typically 50-120 mm. 7 feeders 57-140 mm. In the embodiment shown in Figs 1 to 4, where eight feeder units 2 are adapted to be distributed substantially evenly, the diameter of the imaginary inner circle is typically 65 to 150 mm, in the specific embodi- ment approximately 107 mm. These values are dependent also on the desired clearance of 1 -10 mm between parts of neighbouring feeder units and the dimensions of the individual parts. In the embodiment shown, the approximate width 26 of the discharge tube of each feeder unit 2 is 40 mm.
• the dimensioning of the feeder units 2 of the feeder module 1 de- pends on the field of application. Sizing may for instance be available as a range, such that each feeder unit 2 in a module 1 is of a different size.
• the dead weight of each feeder unit 2 is below 5 kg, and the capacity of the storage hopper of each feeder unit is less than 2 liters.
• the net weight of the powder to be filled into the storage hopper 21 of the individual feeder units 2 depend on the volume but also on the kind of powder applied.
• the maximum volume of powder in the storage hopper lies in the interval 1 .6 to 2 liters.
• the maximum mass flow rate is approximately 50 kg/h.
• the ratio of powder weight and the maximum mass flow provide a maximum run time to empty a feeder or a maximum refilling interval pr. hour.
• the arithmetic product of the maximum refilling interval [h] and the dead weight [kg] of each feeder unit 2 is below 0.1 kgh. If the powder density is taken out of the equation and replaced by volume the maximum refilling interval is also the ratio of the hopper volume [L] and the federate [L/h]. E.g the capacity of the storage hopper of each feeder unit is less than 1 .6 liters. The maximum flow rate is 100 L/h. The maximum refill interval is then 0.016h.
• the dead weight of each feeder unit 2 is typically 5 kg.
• the arithmetic product of the dead weight 5 kg and the maximum refill interval 0.016h is 0.087kgh.
• the arithmetic product is typically below 0.2, preferably below 0.1 , most preferably below 0.05 kgh.
• the storage hopper, the conveyer and the discharge end of each feeder unit are releasably con- nected to the weighing cell .
• Fig. 4 shows a detail cross section of the receiving hopper or receiving container 3.
• the discharge tube end 23 of the feeder units 2 with the imaginary circle 31 is smaller than the diameter of the receiving container 3.
• the discharged powder falls straight into the throat of the receiving container 3 and is substantially not hooking up to the inner walls of the receiving container 3.
• the configuration of the feeder units 2 of the feeder module is slightly different from that of Figs 1 to 4.
• Detachment of one feeder unit 2, for instance for cleaning purposes, is carried out by detaching the feeder unit 2 from the receiving container 3. This may take place in a contained manner, for instance by other tightening or sealing devices, such as by Layflat tubing (LFT).
• LFT Layflat tubing
• a casing 250 is provided around the storage hopper, the conveyer 22 and the discharge end 23 of each feeder. The openings in the casing 250 are detached from the weighing cell.
• the receiving container, which is also detached from the weighing cell, and the feeder part 20 are isolated in a contained way by means of a lay flat tube 260.
• Lay flat tubes 260 are preferably made of a lightweight material having a very low stiffness, such that the weighing signal is left almost completely unaffected.
• a lay flat tube 260 may also be provided between the storage hopper 21 and a pre-feeder element (see Fig. 1 ).
• Refilling of the storage hoppers of the feeding units 2 may take place at different points in time, if expedient according to a predefined schedule.
• the refilling takes place by means of a valve with air compensation, cf. part 25 shown in Figs 8a-c. Suitable valves are represented by plug valves, rotary dosing valves 41 , butterfly valves 42 and slide valves 43. Above the valve a level sensor 44 is provided for use when the weight is fluctuating during refill of the feeder unit 2.
• the refilling takes place in a contained manner so as to at least assure that no dust enters the surrounding environment by the use of an appropriate seal or tube.
• the storage hopper 21 may be supplemented by a stirrer device 21 1 to break any bridges formed in the powder and to ensure that the conveyer 22 is fed properly.
• the conveyer 22 is in the embodiment shown a twin screw conveyor.
• the feeder unit 2 is additionally provided with lay flat tubing 260 and the receiving opening of the storage hopper 21 and at the discharge end 23.
• both of the concave screws 221 and 222 of the twin screw conveyor 22 have a variable pitch along its length, a first pitch p1 and a second pitch p2, being different from the first pitch P1 .
• the conveyer 22 is driven by a motor M.
• the diameter of ach screw is constant.
• the pitch of each screw is constant, whereas the diameter of the screws is variable along the length shown as diameter d1 and diameter d2. It is also possible to have one or more screws with both a variable pitch and a variable diameter.
• the feeder module may comprise a number of additional features, such as analysis and control systems, loading and discharging stations etc.
• the feeder unit of the feeder module has a storage hopper of a limited volume, a rapid or high frequency refilling system is provided.
• feeders of a larger volume are refilled 4 to 8 times per hour.
• the powder which is dropping into the storage hopper causes disturbances on the weight signal (due to the impact forces of the powder) over a period which is equal to the sum of the powder drop time and scale stabilization time. Together with the time of rolling average filters this usually takes 30 s up to 60 s to get a stable weighing signal after a refill or top-up.
• the feeder is running in a volumetric mode.
• the screw speed is defined by the Feed Factor curve, the feed factor being defined as the equivalent of the weight per screw revolution, and the accuracy depending on how good the curve is fitting to the reality.
• Typical values of the refilling frequency of the feeder module according to the invention are one time per minute at a feed rate of 50 kg/h, i.e. mass flow 5 kg/h refill after 10 min. Due to its reduced weight and dynamic properties, the feeder module stabilizes in 2 to 4 seconds at a feed rate of 50 kg/h.
• the summarized refill time of both systems is similar, but the accuracy on the mass flow during refilling volumetric mode (RMS error) is much better compared to conventional top-up systems.
• the principle underlying the refilling system of the feeder module according to the invention is different from others as it is based on refilling each time the same amount of power under the same conditions.
• the refill system has either a weighing scale or a level sensor integrated combined with a volumetric dosing valve.
• the system itself acts as a (pre)feeder and stores the number of impeller turns together with a level or a weight.
• Such a refill or top-up system can also be used for material determination using the feeder data. Furthermore, it can be set to sense material variations. As the powder dosing valve always discharges in the center of the top-up tube, the shape of the powder stack is constant in the same area. During the powder drop, the powder at the bottom of the hopper is more com- pacted than the powder at the top of the hopper. However, the powder volume in the discharge tube is still not compacted. The screw speed remains unchanged until the fresh (i.e. more compacted) material is coming to the discharge opening. Each refill is reproducible and the system learns and converges to the optimal speed of the screws.
• feeder data may be used to calculate theoretical compositions and confirm BU and Assay over specified time periods.
• FFT fast Fourier Transform
• the feeder module is subjected to a number of ex- ternal and internal disturbances.
• the disturbances normally include mechanical vibrations, wind load, bellow deformation forces etc. falling into one of two main types, viz. deterministic disturbances, which can be filtered, and non- deterministic disturbances, the effect of which must be reduced in other ways.
• deterministic disturbances which can be filtered
• non- deterministic disturbances the effect of which must be reduced in other ways.
• AVC Active Vibration Com- pensation
• the feeder module according to the invention is dynamically more precise and faster responding compared to others. For instance, the recovery from non-cyclic external disturbances will only take about 2 to 4 seconds.
• a controller adapted to store a conveying parameter together with a level or a weight may be provided, and the feeder unit may further comprise a sensor for sensing material variations.
• the method is intended for discharging a constant mass flow of one or more powders into a receiving container. Primarily, the method forms part of a process for processing pharmaceutical products, but may also be applied in other fields.
• the method is suitable for being operated in a feeder unit 2 as described in the above and comprises the steps of:
• a feeder unit 2 with a storage hopper 21 , a weighing cell 24, a conveyer 22, and a discharge end 23,
• the refilling valve 41 , 42, 43 dispenses the same amount of powder into the storage hopper 21 , and
• the conveyer 22 is operated according to the data collected during previous refills.
• the storage hopper 21 is refilled 40 to 80 times per hour, preferably 50 to 70 times per hour.
• the stabilizing time after each refill is in the range 2 to 4 seconds.
• a working space is defined by the value resulting from the formula:
• the arithmetic product of the dead weight [kg] of each feeder unit and the refilling interval [h] is below 0.2 or even below 0.1 . Due to the low powder mass in the hopper a very sensitive scale can be used which leads to a very high accuracy. The low powder mass makes a more frequent refilling neces- sary.
• the storage hoppers of the respective feeder units are refilled intermittently as described in the above.
• the method may include the further steps of detaching the storage hopper, the conveyer and the discharge end of each feeder unit from the weighing cell, and cleaning the storage hopper, the conveyer and the discharge end of each feeder unit in a contained manner.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Quality & Reliability (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Filling Or Emptying Of Bunkers, Hoppers, And Tanks (AREA)

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Citations (4)

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• 2012
  • 2012-06-04 IN IN11260DEN2014 patent/IN2014DN11260A/en unknown
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  • 2012-06-04 US US14/404,972 patent/US20150183531A1/en not_active Abandoned
  • 2012-06-04 WO PCT/IB2012/052803 patent/WO2013182869A1/en not_active Ceased
  • 2012-06-04 EP EP12729233.2A patent/EP2856089B1/en not_active Revoked
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