EP0148360B1 - Method of compacting and/or filling pulverulent materials - Google Patents

Description

The invention relates to a method for compacting and / or filling powdery substances in rigid or flexible containers, wherein the powdery substance is filled into the container by means of at least one tube, which can carry out a filling movement relative to the container within the container, and the powdery substance by means of a separating device (2) from the fluidizing medium which may be present or retained in the container, while the fluidizing medium which may be present is allowed to escape from the container through the gas-permeable surface of the separating device by means of a suitable pressure gradient.

Such a method is known from US-A-2 352 663.

Powdery materials are placed in flexible or rigid containers, such as. B. drums or sacks. Some powdery substances, in particular pyrogenic oxides or mixed oxides of metals and / or metalloids, such as. B. pyrogenic silicon dioxide, have a low bulk density and / or are heavily permeated with air. These properties require large containers for filling and transport, which inevitably result in high packaging and transport costs.

Filling systems are known which allow the pulverulent substances to be vented (compressed) at the same time during filling. Due to the increased bulk density of the filled powdered substance, smaller containers are required or larger quantities of powdered substance can be introduced into existing containers. Storage space is saved and transportation costs are reduced.

US-A-2 352 663 describes a device for packaging flour, feed or bran in containers or bags according to the preamble of claim 1.

This device basically consists of a tube, in which a screw rotates at high speed (approx. 2000 revolutions per minute) at the lower end.

With this screw, the flour or the like should be compacted at high speed. Since the filling tube is screwed up from the bottom of the container by means of the screw, it stands on the compacted material after filling. The problem of air discharge from the compacted flour or the like is solved as follows:.

According to column 4, line 55 ff, on the one hand, the air is passed through the channels 44 (FIGS. 3 and 5) via the screw.

On the other hand, the air is returned upwards through the space 48 into the flour mass to be filled.

This method is not suitable for the packaging of synthetic silicas and in particular for the packaging of pyrogenic silica, because fluidized pyrogenic silica behaves like a thin liquid (analogous to water).

There would be no compression at all in the packaging.

Another major disadvantage of the known method is that the air that is released during compression is returned to the bulk material and flows in countercurrent to the bulk material via the telescopic tube. This can cause traffic jams in the conveyor system.

Another disadvantage is that the flour is mechanically stressed by the high speed of rotation of the screw.

• - die Carter-Vac-Abfüllanlage zum Abfüllen pulverförmiger Produkte in flexible, gasdurchlässige Behälter, wie z. B. Ventilsäcke, mittels einer vollständig geschlossenen Abfüllkammer; (CARTER-FILLER)
• - der Gerivac-Durchlaufverdichter zum Verdichten pulverförmiger Produkte vor der Abfüllung in Kleinpackungen, Beutel, offene Säcke oder Fässer (vgl. Chemische Rundschau 25 (1971), Nr. 21, Seite 647).

The following two old bottling lines are known:

• - The Carter Vac filling system for filling powdered products into flexible, gas-permeable containers, such as B. valve bags, by means of a completely closed filling chamber; (CARTER-FILLER)
• - the Gerivac continuous flow compressor for compacting powdery products before filling into small packages, bags, open sacks or barrels (cf. Chemische Rundschau 25 (1971), No. 21, page 647).

• a) Nach Beendigung des Füllvorgangs existieren hohe Dichteunterschiede innerhalb des im Behälter befindlichen pulverförmigen Stoffes (Dichteschwankungen ca. ± 20 %, bezogen auf die mittlere Dichte p) zwischen dem pulverförmigen Stoff in der Behältermitte und dem pulverförmigen Stoff an den Behälterwänden
• b) Eine zu starke Erhöhung des Behälterinhaltes bedingt eine zu starke Erhöhung der mittleren Dichte der pulverförmigen Stoffe, wie z. B. bei pyrogen hergestelltem Siliciumdioxid, und führt zu überproportionaler Verlängerung der Füllzeit und teilweise zu unerwünschten Veränderungen der anwendungstechnischen Eigenschaften des pulverförmigen Stoffes. So benötigt die Erhöhung der mittleren Dichte von pyrogen hergestelltem Siliciumdioxid von 60 auf 75 g/I (= 25 %) eine Verlängerung der Fülllzeit um ca. 125 %.
• c) Ein hoher Verpackungskostenanteil wird durch die hohen Behälteranforderungen, wie z. B. Ventilsäcke mit hohen Festigkeitsanforderungen, verursacht.
• d) Die Bindung an ein eng definiertes, gasdurchlässiges Sackmaterial verbietet zum Beispiel die Verwendung von weitgehend oder völlig gasundurchlässigem Sackmaterial, welches den Zutritt von z. B. Feuchtigkeit zu dem pulverförmigen Stoff verhindern kann.

The known filling process using CARTER-FILLER has the following disadvantages:

• a) After the filling process has ended there are high density differences within the powdery substance in the container (density fluctuations approx. ± 20%, based on the average density p) between the powdery substance in the middle of the container and the powdery substance on the container walls
• b) An excessive increase in the contents of the container causes an excessive increase in the average density of the powdery substances, such as. B. in pyrogenic silicon dioxide, and leads to a disproportionate increase in the filling time and sometimes to undesirable changes in the application properties of the powdery substance. For example, increasing the average density of pyrogenically produced silicon dioxide from 60 to 75 g / l (= 25%) requires an increase in the filling time by approx. 125%.
• c) A high proportion of packaging costs is due to the high container requirements such. B. valve sacks with high strength requirements.
• d) Binding to a narrowly defined, gas-permeable sack material prohibits, for example, the use of largely or completely gas-impermeable sack material which prevents the access of e.g. B. can prevent moisture to the powdery substance.

The known filling method by means of a flow compressor has the disadvantage that the powdery material is loosened again on the way into the container after the compression. If a specific density is to be achieved in the container, this can only be achieved by over-compressing the pulverulent substance in the compacting device. There is a risk that the application properties of the powdery substance, such as. B. the dispersibility, could be changed in an undesirable manner.

The object of the invention when filling powdery substances, in particular in the case of pyrogenically produced oxides or mixed oxides of metals and / or metalloids, for example of pyrogenically produced silicon dioxide, is to achieve a homogeneous consistency in the entire container volume range and an increase in the mean consistency in the Containers without undesirable changes in the application properties, e.g. B. dispersibility and thickening effect.

This object is achieved by the method according to the invention.

The invention relates to a method for compacting and / or filling powdery substances in rigid or flexible containers, whereby the powdery substance is formed by means of at least one tube (1) which performs a filling movement relative to the container (6) within the container (6) can be filled into the container (6) and the pulverulent substance separated from the possibly present fluidizing medium by means of a separating device or retained in the container (6), while the possibly existing fluidizing medium is removed through the gas-permeable surface of the separating device (2) allows the container (6) to escape by means of a suitable pressure gradient, which is characterized in that the separating device surrounds the pipe (1), is optionally arranged flush at the open end of the pipe (1) and a gas-solids separator which is suitable and which Container cross-section has an essentially dust-proof adapted surface, and that the filling level and thus optionally determines the degree of compaction of the powdery substance in the container by means of the respective position of the separating device (2).

In a special embodiment of the invention, the pulverulent substance for filling can be removed from a storage container by means of a fluidizing medium, in particular fluidiser air, and optionally also conveyed in a line to the filling device by means of a transport device.

Before the powdery substance is poured into the container, the pipe with the separating device can first be led to the bottom or near the bottom of the container and then moved to the opening of the container in the form of a filling movement. The filling movement can be brought about by the pressure of the pulverulent substance or gas / solid mixture in the container, wherein a counterforce, which is less than or equal to the compressive force of the pulverulent in the container, is optionally exerted on the pipe and thus also on the separating device Substance, or gas / solid mixture.

The filling movement can also be driven mechanically, pneumatically or hydraulically. In addition, the pipe can be oscillated in the direction of its longitudinal axis with the separating device. which overlays the actual filling movement. The oscillating movement can take place periodically or non-periodically with different strokes. The amount of pulverulent substance can be metered volumetrically, the variable volume of the space remaining between the tank bottom, the tank walls and the separating device or gravimetrically using a scale.

Any commercially usable gaseous substance, such as air, nitrogen or carbon dioxide, can be used as the fluidizing medium. be used. Air is preferably used as the fluidizing medium.

A device suitable for conveying gas / solids, such as a diaphragm pump, a gear pump or an eccentric screw pump, can be used as the transport device.

Another transport device for conveying the gas / solid mixture can be a pressure vessel. A suitable operating pressure is applied to this pressure vessel. Fluidizing air can be applied to the bottom of the pressure vessel during emptying.

The filling of the powdery substance can also be carried out simultaneously with several, for example two or three pipes. It is essential that these tubes are connected at their open end, possibly flush with the same separating device.

The pressure drop on the surface of the separating device that is unified for gas / solid separation can be generated by means of excess pressure in the fluidizing medium and / or by negative pressure at the container opening or the separating device.

Preferably, an overpressure by the transport device, for. B. generated by means of a diaphragm pump or an overpressure container.

The pressure drop can be constant over time or intermittent.

The area suitable for gas / solid separation can, for. B. made of sintered metal or more porous Ceramics exist. In another embodiment of the invention, the surface of the separating device can consist of a gas-permeable fabric or felt made of wire or natural or synthetic organic or inorganic fibers, which are arranged on stable, gas-permeable supports. For example, a perforated plate can be used as a stable support.

The surface suitable for gas / solid separation can be flat or curved. If the surface is curved, the tube or the tubes with the open end can be arranged on the concave side or on the convex side of the hollow body formed by the curved surface.

The surface suitable for gas / solid separation should be largely dust-tightly adapted to the container wall. For sealing you can, for example, brushes or a ring with a suitable, e.g. B. round, cross section of elastic hollow or solid material. It is essential that the surface suitable for gas / solid separation can slide sealingly in the container.

The interior of the rigid or flexible container should have a constant congruent cross-sectional area perpendicular to the longitudinal axis of the container, which is identical to the axis of the filling movement, along its longitudinal axis. This provides an adequate seal between the container wall and the separating device over the entire fill level.

The completion of the filling can take place in such a way that the gas / solid mixture conveyance and the relative movement from container to tube with separating device are ended at the same time, or that the relative movement from container to pipe with separating device is terminated before the gas / solid mixture conveyance has ended completed.

During filling, the container, preferably with flexible containers, such as. B. sacks, are enclosed by a support structure that can absorb the mechanical stress that occurs during filling.

An advantage of the process according to the invention is that a higher average and more uniform density of the pulverulent substance in the container is obtained, the good application properties being retained. It allows greater flexibility in adjusting the average density of the powder in the container. Simpler and therefore cheaper containers can be used. A particular advantage is that largely gas or moisture-tight containers can be used. This means greater freedom in the choice of the material of the container.

The inventive method is suitable for filling carbon black, color pigments and / or silicas, such as. B. precipitated or pyrogenic silicas. The method according to the invention is preferably suitable for filling pyrogenically produced oxides or mixed oxides of metals and / or metalloids, in particular of pyrogenically produced silicon dioxide.

The method according to the invention is explained in more detail with reference to the drawing.

• Figur 1 das Abfüllen mittels einer gewölbt ausgebildeten Fläche der Abtrennvorrichtung, auf deren Konvexseite ein Rohr derart angeordnet ist, daß dessen Öffnung mit der Konkavseite der Fläche bündig abschließt.
• Figur 2 das Abfüllen mittels einer eben ausgebildeten Fläche der Abtrennvorrichtung auf der zwei Rohre derart angeordnet sind, daß deren Öffnungen mit der den Rohren gegenüberliegenden Seite bündig abschliessen.
• Figur 3 das Abfüllen mittels einer gewölbt ausgebildeten Fläche der Abtrennvorrichtung, auf deren Konkavseite ein Rohr, durchgehend bis über die Konvexseite der Fläche hinaus, angeordnet ist.

Show it

• Figure 1 the filling by means of a curved surface of the separating device, on the convex side of which a tube is arranged such that its opening is flush with the concave side of the surface.
• Figure 2 shows the filling by means of a flat surface of the separating device on which two pipes are arranged such that their openings are flush with the side opposite the pipes.
• 3 shows the filling by means of a curved surface of the separating device, on the concave side of which a tube is arranged, continuously up to beyond the convex side of the surface.

According to FIG. 1, the tube 1 is arranged on the separating device 2 on the convex side, the opening of which is flush with the concave side of the surface. This consists of the perforated plate 3 on which the separating surface 4 for the separation of the gas / solid mixture is arranged.

The separating device 2 is surrounded by the ring 5 made of elastic material, whereby a largely dust-tight seal between the separating device 2 and the flexible wall of the container 6 is given. The flexible wall of the container 6 is fastened in the frame 7 by means of the bracket 8.

The pulverulent substance mixed with air is conveyed through the pipe 1 into the space 9 between the separating device 2 and the flexible wall of the container 6. The pulverulent substance is retained in this space 9 by the separating device 2, while the air escapes through the opening 10 of the separating device 2.

According to Figure 2, the separation device 2 is flat. In addition to the pipe 1, the pipe 1 'is arranged flush on the separating device 2.

The wall of the container 6 is made of rigid material, so that a support structure is not required. To increase the stability, the container 6 is placed on the platform 11.

According to FIG. 3, the separating device 2 is curved, the tube 1 projecting beyond the separating device 2 into the space 9. The tube 1 is arranged on the concave side of the separating device 2. Furthermore, the same arrangement as in FIG. 1 is used.

The method according to the invention can be carried out as follows:

The tube 1, to which the separating device 2 is attached, is inserted into the container down to the bottom of the container. Then the gas / solid mixture, a pyrogenic silicon dioxide fluidized with air and transported by means of a pressure vessel and fluidizing air, is allowed to flow into the closed space 9 formed between the vessel bottom, vessel walls and separating device via the tube. The pulverulent substance remains in this space 9, while the fluidiser air escapes from the container 6 through the gas-permeable surface of the separating device 2.

Simultaneously with the inflow of the gas / solid mixture into the space 9 between the tank bottom, the container walls and the separating device 2 or after a suitable time delay, the pipe 1 with the separating device 2 moves in a guided relative movement due to the force relationships on the separating device 2 from those to be filled Container 6 out.

example 1

A cross-bottom bag with the dimensions 550 x 220 x 1300 mm is attached to the bracket 8 and then slid over the separating device 2 by raising the frame 7 with the bracket 8 until the separating device 2, which has a needle felt surface, on the bag bottom or in whose proximity has reached.

Now the fluidized, pyrogenically produced silicon dioxide with a specific surface area of approx. 200 m ² / g and a tamped density according to DIN 53 194 of 35 g / I is pumped through a tube 1 through the pipe 1 into the room 9, the filling pressure being approx 0.5 bar. After the filling pressure has been reached, the frame 7 with the bag 6 is lowered at a lifting speed of approximately 0.6 m / min until the separating device reaches the filling end position. After a time delay of 0-5 seconds, the gas / solid mixture delivery is stopped by switching off the pump and the separating device is moved out of the cross-bottom bag by further lowering the frame 7.

The cross bottom sack is filled to a height of approx. 1100 mm with 10 kg of pyrogenic silicon dioxide. The average density of this product is 75 g / I with a density fluctuation of + 5 / -10 g / I.

The application properties of the filled pyrogenically prepared silicon dioxide have not changed adversely.

Example 2

A container 6, consisting of 12 rings with an inner diameter of 80 mm and a height of 20 mm each, the bracing elements and a base made of a plastic film on a support plate, is attached to a frame 7 and then moved upwards with a lifting device. During the upward stroke, the stationary tube 1 with the separating device 2 slides relatively downward in the container to be filled in the direction of the container bottom until the distance between the separating device 2 and the container bottom is approximately 10 mm.

The separation device 2, at the lower end of the tube 1, consists of a perforated plate on which a filter fabric LAINYL M9 / S5 / HCa .. is attached as a separation surface 4. The separating pre-seal is sealed against the container 6 by means of an O-ring 5.

Now the fluidized, pyrogenically produced silicon dioxide with a surface of approx. 200 m ² / g and a tamped density according to DIN 53 194 of approx. 35 g / I is pumped through a tube 1 through the pipe 1 into the room 9, the filling pressure being approx 0.5 bar. After the filling pressure has been reached, the container 6 is lowered at a stroke speed of approximately 0.6 m / min until the separating device reaches the filling end position. After a time delay of 0-5 seconds, the gas / solid mixture delivery is stopped by switching off the pump and the separating device is moved out of the container 6 by further lowering the frame 7.

The container is filled to a height of approx. 250 mm with pyrogenic silicon dioxide. The silicon dioxide has an average density of approx. 67 g / I with a fluctuation range of the average density in the individual ring elements of the container of + 3 / - 5 g / I.

The application properties of the filled pyrogenically prepared silicon dioxide have not changed adversely.

• LAINYL M9/S5/4Ca
• Monofiles Rilsan 11-Gewebe
• Gewicht ca. 355 g/m2
• Luftduchlässigkeit nach DIN ca. 500 I
• kalandriert

The filter fabric used is marked as follows:

• LAINYL M9 / S5 / 4Ca
• Monofilament Rilsan 11 fabric
• Weight approx. 355 g / m2
• Air permeability according to DIN approx. 500 I
• calendered

Claims (4)

1. A process for compacting and/or packing powder-form materials in rigid or flexible containers, the powder-form material being introduced into the container (6) through at least one tube (1), which is designed to make a filling movement relative to the container (6) inside the container (6), and being separated from the fluidizing medium optionally present and retained in the container (6) by means of a separator (2) while the fluidizing medium optionally present is allowed to escape from the container (6) through the gas- permeable surface of the separator (2) by means of a suitable pressure gradient, characterized in that the separator (2) surrounds the tube (1), is arranged, optionally flush, at the open end of the tube (1) and has a surface suitable for gas/ solids separation which is adapted to the cross-section of the container in substantially dust-tight manner and in that the filling level and hence, optionally, the degree of compaction of the powder-form material in the container is determined through the particular position of the separator (2).

2. A process as claimed in claim 1, characterized in that, for packing, the powder-form material is removed from a storage container by means of a fluidizing medium, more especially fluidizing air, and is transported through a pipe to the packing station, optionally with the additional assistance of transport means.

3. A process as claimed in claim 1 or 2, characterized in that, before the powder-form material is introduced into the container, the tube is first guided with the separator to the base or into the vicinity of the base of the container and is then allowed to move towards the opening of the container in the form of a filling movement.

4. A process as claimed in claim 3, characterized in that the tube is allowed to make an oscillating movement superimposed on the actual filling movement with the separator in the direction of its longitudinal axis.

Images