Method for dedusting in batches

Abstract

The invention relates to a method for dedusting a granulate (G) in batches, said method having the following steps: - filling a dust-removing container (12) with a granulate (G), - carrying out a first dedusting process on the introduced granulate (G) in the dedusting container (12) by means of an introduced gas, - carrying out a second dedusting process on the introduced granulate (G) in the dedusting container (12) by means of an introduced gas, and - emptying the dedusted granulate (G) from the dedusting container (12). The invention also relates to a dedusting device for carrying out such a method.

Description

[0001] Method for batch dust removal

[0002] Description

[0003] The present invention relates to a method for batch-wise dedusting of a granulate by means of a dedusting device, whereby the dust adhering to the granulate grains is removed, and to a dedusting device for carrying out such a method.

[0004] Especially in plastics engineering, but also in pharmaceuticals and food technology, raw materials in the form of bulk goods, such as granules, ground materials, or similar substances, often need to be handled. For the purposes of this application, all types of bulk goods will be referred to by the shortened term "granules".

[0005] The transport of such bulk materials is often carried out using pneumatic conveying, especially by means of air conveying, in which the granules are brought to the desired location by means of an airflow and mostly carried along in it through conveying lines.

[0006] The granules should be as clean as possible for further processing, for example, use as raw material in a plastic injection molding machine, and in particular should not be contaminated with dust-like impurities. Such dust-like impurities can consist of foreign material that was unintentionally added to the granules during production or transport, or they can also be dust-like particles made of the same material as the granules themselves, which, however, may also be undesirable depending on the subsequent application. Dust or dust-like impurities within the meaning of this application should preferably have a particle size whose diameter is at most 1 / 10, better at most 1 / 30, better at most 1 / 100, better at most 1 / 1000 of the diameter of a granule grain.

[0007] Accordingly, the general aim is to separate such granules from the dust content before their use, for which various techniques are available, ranging from simple sieving to separating the transport air from the granules and filtering the transport air, to fraction separation using a cyclone.

[0008] One of the problems frequently encountered here is the strong adhesion of dust particles to each other and to granule particles, as well as the adhesion of dust particles to equipment components such as conveyor lines or granule containers. Such strong adhesion is often caused by electrostatic charging, meaning that dust removal by mechanical means is generally only possible once these binding forces, especially the so-called Lorentz force, have been overcome. In principle, this is known to be possible by discharging the oppositely charged and therefore attracting parts—in this case, dust particles on the one hand and granule particles on the other—each by grounding one fraction. However, with the very large number of very small particles in this application, this is difficult in practice.

[0009] On the other hand, attempts have also been made to separate the granules by constantly stirring them up in a dust collection container sealed at the bottom and bringing them into close contact with ionized air. However, this can generate further abrasion and thus dust due to the induced collision of granule particles.

[0010] As prior art, reference is first made to EP 2711 097 A1, which teaches a device for batch dedusting of granules with a flow generator arranged downstream of a dedusting container in the form of an ejector compressed air nozzle with a compressed air connection and a dedusting container, which in turn has at least one granule inlet opening, a granule outlet opening in a lower part of the dedusting container, an air outlet opening, which is arranged in particular in the upper part of the dedusting container, an ionizer, a swirling unit for swirling the granules in the dedusting container, a control for controlling the swirling unit and all moving parts and circumferential walls surrounding the dedusting container which consist of an electrically non-conductive material, wherein the swirling unit further comprises an upwardly directed swirling nozzle.which is connected to a compressed air connection.

[0011] Furthermore, reference is made to WO 2018 / 073053 A1, in which an attempt was made to extract dust-laden air from a granule container via an air outlet opening, rather than forcing it out by means of overpressure, with the air outlet opening being closed by a sieve. Additionally, WO 2016 / 041968 A1 discloses several nozzles in an outlet opening of a similar system, which form part of a sealing element.

[0012] While existing devices and methods already deliver relatively satisfactory results in some cases, there is always a desire for further improved dust removal performance combined with the potential to increase the material throughput. Furthermore, gentle conveying and dust removal of the granules are desired, as well as a device with a small footprint, low weight, few moving parts, and low manufacturing costs.

[0013] To solve this problem and to overcome the disadvantages of the prior art described above, a method for batch dedusting of granules by means of a dedusting device is proposed according to the invention, by means of which the dust adhering to the granule grains is removed, wherein the method comprises the steps of filling a dedusting container with granules, first dedusting the filled granules in the dedusting container by means of introduced gas, which is introduced into the dedusting container via a swirling unit comprising nozzles and / or an annular gap, wherein a main flow direction of the gas introduced into the dedusting container via the swirling unit is essentially opposite to the force of gravity acting on the granules.so that the granules are lifted and agitated, and the dust adhering to the granules is loosened and discharged from the dust collection container via a gas outlet; a second dust collection of the granules in the dust collection container by means of introduced gas, in particular air, which is introduced into the dust collection container via a granule discharge opening, through which the granules can be conveyed by gravity into an intermediate granule container; the gas introduction via the granule discharge opening is caused by a negative pressure generated downstream of the gas outlet; the main flow direction of the gas introduced into the dust collection container via the granule discharge opening is essentially opposite to the force of gravity acting on the granules; and the gas flow is sufficiently strong.to prevent the majority of the granules from falling through the open granule outlet, so that the granules are lifted and agitated, and the dust adhering to the granules is loosened and discharged from the dust collection container via the gas outlet, and finally, the dedusted granules are emptied from the dust collection container.

[0014] Accordingly, the method according to the invention enables the sequential dedusting of the granules by means of a first and a second dedusting step, which are also referred to as first and second air classification, respectively, thereby improving the overall dedusting result. It should be noted that the first and second dedusting steps can be carried out in any order; that is, either the agitation unit can be operated first, or gas can be introduced into the dedusting container via the granule outlet. Furthermore, it is understood that the parameters of the corresponding gas flows in the two dedusting steps can be selected depending on the properties of the granules to be treated and can, for example, be individually adjusted after each filling of the dedusting container.

[0015] Furthermore, it is evident that the two dedusting steps are carried out in a single dedusting container, so that, in order to achieve the improved dedusting result in the method according to the invention, the volume and complexity of the device used are only minimally increased, if at all.

[0016] Furthermore, it should be noted that, depending on the nature of the granules to be dedusted, it may be necessary to carry out the first and second dedusting several times in succession in order to achieve a satisfactory dedusting result, whereby, according to the invention, in principle any number of successive cycles with first and second dedusting are conceivable.

[0017] According to the invention, the gas used in the first dust removal process can comprise an ionized gas, in particular ionized air, which is preferably mixed into the dust removal container, especially by lateral inflow. Mixing the ionized air into the dust removal container prevents the generated ions from being immediately neutralized upon contact with metal, as could happen, for example, if they were introduced via the agitation unit. Furthermore, by neutralizing any potential static charge on the granules and / or dust, separation can be simplified and the dust removal result improved.

[0018] Furthermore, the method according to the invention can include blowing out the dust collection container after emptying the granules, preferably by means of the agitation unit, in order to remove any particles remaining in the dust collection container. In particular, this step helps to avoid any dust contamination of a new dust collection batch, which may necessitate rinsing processes between the respective dust collection cycles, which, for example, can only be carried out by the aforementioned blowing out.

[0019] Alternatively or additionally, for a similar purpose, a first and / or second ion purging of the dust collection container can be included after emptying the granules from the dust collection container and before or after blowing out the dust collection container in the method according to the invention, preferably using the swirling unit and the unit already mentioned above, which allows the lateral inflow of ionized gas.

[0020] In addition, after emptying the granules from the dust collection container and, if necessary, blowing out and / or the first and / or second ion rinsing, it is possible to carry out a final cleaning of the dust collection container, in which any suitable cleaning techniques can be used and in particular vacuuming the dust collection container.

[0021] Although, as mentioned above, the parameters of the gas flows in the two dust removal steps can be chosen depending on the properties of the granules to be dusted, it should nevertheless be noted that the volume flow of the gas introduced during the first dust removal can be, in particular, less than 1,000 liters per minute, preferably less than 600 liters per minute, and further preferably less than 400 liters per minute.

[0022] In this context, it should be noted again that the procedure may include adjusting the airflows for the first and second dust removal and, if necessary, cleaning and / or conveying the granules in the dust removal containers, for example in connection with determining or accessing known properties of the granules, such as their particle size, density and / or dust content, or, alternatively, taking into account a cleaning result of a previous batch of granules obtained by suitable means, in order to establish a follow-up adjustment process.

[0023] Furthermore, it should be noted that a batch of granules to be dedusted may in particular comprise less than 500 ml, preferably less than 400 ml of granules.

[0024] As already indicated above, according to a further aspect, the present invention relates to a dust collection device for carrying out a method according to the invention of the type just described, comprising a dust collection container with a granule inlet opening, a granule outlet opening arranged in a lower region thereof, a gas inlet and a gas outlet which is configured to receive granules to be dusted, a swirling unit which comprises nozzles and / or an annular gap and is configured to introduce a gas into the dust collection container such that a main flow direction of the gas introduced into the dust collection container via the swirling unit is essentially opposite to the force of gravity acting on the granules, an intermediate granule container which is arranged below the granule outlet opening and has an air inlet, and an airflow generator which is configured toto generate a gas flow from the gas inlet to the gas outlet, and a control unit which supplies the swirling unit, the airflow generator and preferably an ejector suction lance, an ionizer and a sealing element with pressurized gas and evaluates signals from a level sensor in order to carry out a method according to the invention of the type described above.

[0025] It should be noted that for the second dust removal step described above, both a blower-based vacuum generator and a compressed air ejector are suitable, whereas for the first dust removal step, only a compressed air source is suitable. In any case, the design of the dust removal device according to the invention makes it possible, with a compact design using only a single dust removal container, to carry out the two dust removal steps sequentially and, if necessary, multiple times, in order to achieve the desired dust removal result in a compact system and with a high material throughput.

[0026] The dust collection container can be tapered downwards towards the granule outlet opening, preferably conically tapered, and / or its underside can be selectively closable by a closure. Furthermore, the gas outlet can be located in an upper region of the dust collection container, particularly in its ceiling, and is preferably covered by a screen. The gas outlet can either be permanently open or selectively closable by means of a flap or similar device.

[0027] Furthermore, the dust removal device according to the invention can include an ionizer which is associated with the dust removal container and preferably includes a pressurized gas supply opening to enable the supply of ionized gas in one or more process steps as already described above.

[0028] Furthermore, the dust collection device according to the invention can comprise a granule conveying unit configured to feed the granules to be dusted from a storage container through the granule inlet opening into the dust collection container, in particular by means of a conveying air stream, preferably one whose strength and / or duration can be controlled. The provision of such a conveying unit increases the flexibility and degree of automation of the dust collection device according to the invention, with the control of the conveying unit also being handled by the control unit already mentioned above. Accordingly, the start and end of the conveying process can also be coordinated by the control unit, which then initiates the actual dust collection process with its at least two dust collection steps.Although the geometry and size of the dust removal device according to the invention are not initially defined, it is evident that the dust removal container preferably has a volume of less than 3,000 cm³. 3 exhibits, in particular less than 2,200 cm 3 and / or the inner diameter of the dust collection container is less than 125 mm, preferably less than 100 mm, and more preferably less than 70 mm, and / or at least part of the circumferential wall of the dust collection container is designed as an upright, rotationally symmetrical glass tube open at the top and bottom. Furthermore, the diameter of the granule outlet opening can be less than 50 mm, preferably less than 40 mm, and more preferably less than 28 mm.

[0029] Further features and advantages of the present invention will become even clearer from the following description of an embodiment thereof, when viewed together with the accompanying figures. These show in detail:

[0030] Figure 1 shows a schematic overall view of a device according to the invention in an unfilled state, as well as detailed views of individual components;

[0031] Figure 2 shows the device from Figure 1 during a filling process;

[0032] Figure 3 shows the device from Figure 1 after completion of the filling process;

[0033] Figure 4 shows the device from Figure 1 during a first dust removal step;

[0034] Figure 5 shows the device from Figure 1 during a second dust removal step and a detailed view of some components;

[0035] Figure 6 shows the device from Figure 1 during a draining step;

[0036] Figure 7 shows the device from Figure 1 during an ion rinsing process; Figure 8 shows the device from Figure 1 during a blow-off process;

[0037] Figure 9 shows the device from Figure 1 during a final cleaning; and

[0038] Figure 10 shows a flowchart illustrating the sequence of a method according to the invention, which is carried out using the device from Figure 1.

[0039] Figures 1 to 9, shown in the accompanying illustrations, depict a dust removal device according to the invention under various operating conditions. This device is generally designated by reference numeral 10 and is configured for carrying out a batch dust removal process according to the invention. For clarity, Figure 1 initially shows the dust removal device 10 completely empty and omitting some components. It can be seen that the device comprises a dust removal container 12 with a granule inlet opening 14, a granule outlet opening located in a lower region thereof, a gas inlet 18 formed by the granule outlet opening, and a gas outlet 20. The dust removal container 12 is configured to receive granules to be dusted, which are designated by reference numeral G in some of the further figures.

[0040] Furthermore, the dust collection device 10 comprises a swirling unit 22, which in the embodiment shown here includes an annular gap 22a and which is shown in detail in the enlarged lower left view of Figure 1. The swirling unit 22 is coupled to a compressed air source 24 and is configured to introduce a gas into the dust collection container 12 such that a main flow direction of the gas introduced into the dust collection container 12 via the swirling unit 22 is essentially opposite to the force of gravity acting on the granules G, i.e., in the illustrations used here, points vertically upwards.Furthermore, the enlarged view on the right in Figure 1 shows an alternative variant in which, instead of the annular gap 22a, a plurality of swirl nozzles 22b are provided, which otherwise does not differ from the first variant on the left and above in Figure 1.

[0041] Furthermore, the dust removal device 10 comprises a granule intermediate container 26, which is arranged vertically below the granule outlet opening and has an air inlet 28. The device 10 also comprises an airflow generator 50, which is coupled to the control unit 32 and configured to generate a controlled gas flow from the gas inlet 18 to the gas outlet 20, as well as a control unit 32, which is operationally coupled to the agitation unit 22, the airflow generator 50, and other components described below, and is configured to control each of these components for operation.

[0042] The operation of the device 10 will be explained below with reference to the illustrations in Figures 2 to 9 together with the flowchart from Figure 10, which comprises the process steps of a method according to the invention that is carried out with the device 10. In this context, further components of the device 10 will also be discussed.

[0043] First, in step S1 from Figure 10, the filling step of the dedusting container 12 is carried out, which is shown in Figure 2. For this purpose, it is filled with a batch of granules G, whereby the intermediate container 26, which is open at the top and located below the dedusting container 12 and its lower granule outlet opening, is closed during filling by means of a closure element that can be actuated by compressed air.

[0044] For the purpose of introducing the granules G into the dust collection container 12, a suction lance 34 is inserted into a supply of granules G located in a storage container 36. The granules G are conveyed from the storage container 36 to the dust collection container 12 via the conveying line 38, which is connected to the suction lance 34 and whose other end opens at the granule inlet opening 14 of the dust collection container 12, by means of conveying air that carries the granules along. This is achieved by an ejector nozzle 34a, operated by compressed air, located in or near the suction lance 34. This causes the granules G, supplied via the conveying line 38, to flow downwards out of the granule inlet opening 14 and remain on the sealing element, extending beyond it to the height position of a level sensor 40, which triggers the shutdown of the granule G supply. The compressed air supply to the ejector nozzle 34a in the suction lance 34 is then terminated.

[0045] During the filling process, the conveying air leaves the dust collection container 12 via its air outlet opening 20, which is located in the upper area 12a or lid of the dust collection container 12 and which may be covered by a sieve 42, which can be passed through by the conveying air and any dust it may contain, but not by granules of the granulate G.

[0046] From there, the conveying air, which is now to be considered exhaust air, flows along a dust line 44 to a dust collection container 46 and through an exhaust air vent.

[0047] Filter 48, which is preferably arranged in an outlet opening in the lid of the dust collection container 48, and which is impermeable to dust. The flow of the exhaust air is optionally caused or at least intensified by a negative pressure generator downstream of the air outlet opening 20, in this case again an ejector compressed air nozzle 50, which is either already arranged directly downstream of the air outlet opening 20 in the dust line 44 or can also be arranged downstream of the exhaust air filter 48.

[0048] Such an ejector compressed air nozzle 50, as well as the ejector compressed air nozzle 34a of the suction lance 34 already mentioned above, shoots compressed air - in the present embodiment supplied by the compressed air source 24 already mentioned - in the desired flow direction into the respective transport line 38, 44 and thereby generates an overpressure in the transport line 38, 44 upstream of the corresponding ejector compressed air nozzle 34, 50 and thus a flow of the transport air in this flow direction.

[0049] The sectional views in Figures 1 to 9 clearly show that the dust collection container 12 is an upright, essentially cylindrical container, i.e., with rotationally symmetrical inner circumferential walls that converge towards each other in the lower region at the preferably centrally located granule outlet opening in the form of the outlet cone 16a. The circumferential wall of the cylindrical part of the dust collection container 12 is formed by a tube section made of an electrically non-conductive material, preferably glass, on the open upper surface 12a of which the lid sits, and the open lower surface of which rests on the outlet cone 16a, in which an inner conical surface is formed.In this conical surface of the outlet cone 16a, swirl nozzles 22b of the swirl unit 22 open, through which compressed air can be injected into the interior of the dust collection container 12 to swirl the granules G contained therein. This compressed air is also supplied by the compressed air source 24 in a manner controlled by the control unit 32. Preferably, the outlet cone 16a comprises the annular gap 22a arranged concentrically to the granule outlet opening 16, which is also connected to the compressed air source 24, or, in the alternative variant mentioned above, the swirl nozzles 22b are arranged analogously in the lower right enlarged view of Figure 1.

[0050] Using these components, process step S2 from Figure 10 can now be carried out after completion of the filling process, namely a first dedusting of the granules G in the dedusting container 12, which is also referred to as first air classification. The state of the device after completion of the filling process is shown in Figure 3, while the first dedusting is shown in Figure 4.

[0051] For this purpose, gas is introduced into the dust collection container 12 via the agitation unit 22 in the manner already described, the main flow direction of which is essentially opposite to the force of gravity acting on the granules G, so that the granules G are lifted and agitated, and the dust adhering to the granules is loosened and discharged from the dust collection container 12 via the gas outlet 20. Simultaneously, ionized air is introduced laterally into the dust collection container 12 by means of an ionizer 52 to neutralize the static charge of dust particles and granules of the granules G. The granules of the granules G are agitated and separated, as can be seen in Figure 4.

[0052] The upward movement of the granules is controlled in such a way that they stop their upward motion in a reversal zone and fall back down towards the outlet cone 16a, with the reversal zone being located below the gas outlet 20. In this step, the dissolved dust and gas are discharged from the dust collection container 12 via the gas outlet 20, but not the granules G, thus achieving the first stage of dust removal.

[0053] After this initial dust removal of the granules G has been carried out for a sufficient time, it is stopped, so that the now dust-removed batch of granules accumulates again in the lower area of ​​the dust removal container 12, in particular in the area of ​​the outlet cone 16a.

[0054] According to the flow diagram in Figure 10, a second dedusting process of the granules G in the dedusting container 12 is now carried out in step S3. This process is also referred to as a second air classification and is shown in Figure 5. For this purpose, air is introduced into the dedusting container 12 via the granule outlet opening, through which the granules G can be conveyed by gravity into the intermediate granule container 26. In this second dedusting process, the gas introduction via the granule outlet opening is caused by a negative pressure generated downstream of the gas outlet 20, which flows through the granules G in the dedusting container 12. The main flow direction of the gas introduced into the dedusting container 12 via the granule outlet opening is essentially opposite to the force of gravity acting on the granules G.For this purpose, the gas flow is adjusted strongly enough by the control unit 32 to prevent the majority of the granules of the granule G from falling through when the granule outlet opening is open, so that the granule G is lifted and agitated, and the dust adhering to the granules is loosened and discharged from the dust collection container 12 via the dust line 44 through the gas outlet 20.

[0055] This second dust removal process carried out in step S3 achieves an even better separation of dust from the granules G, and it should be noted that steps S2 and S3 of the first and second dust removal can also be carried out several times in succession, as indicated by a dashed arrow in Figure 10.

[0056] Once the desired purity of the granules G is achieved, the process from Figure 10 can proceed to step S4, namely the emptying step shown in Figure 6. During this step, the dedusted granules are transferred downwards by gravity through the granule outlet opening into the intermediate container 26. From there, they can be fed to a downstream processing step or temporarily stored in the storage container shown below the intermediate container, where they exist as purified granules. Accordingly, after completion of the emptying step in S4, the dedusting container is now empty again and can be prepared to receive a subsequent batch of granules G.

[0057] According to the invention, a multi-stage process can be used to remove dust remaining in the dust collection container 12, thus preventing contamination of the subsequent batch of granules G. In the embodiment of the method discussed here, this preparation process for a subsequent batch comprises the successive steps S5 to S8, namely, first, an initial ion purge S5, which is shown in Figure 7 and is carried out by means of the agitation unit 22 and the ionizer 52 in a similar manner to the first dust removal, but without the presence of granules G in the dust collection container 12. This neutralizes the electrostatic charge of the dust remaining in the dust collection container, which may be adhering, for example, to its inner wall and the glass tube, and facilitates the blow-out process (step S6) shown in Figure 8.

[0058] In step S7, a further step of ion rinsing can then be carried out analogously to step S5 and as shown in Figure 7, before finally, in step S8, a final cleaning is carried out according to Figure 9 by performing the second air classification as shown in Figure 5 or Figure 10, but without granules G in the dust collection container 12, as pure suction. Afterwards, the dust collection container 12 is in a state in which it is prepared to receive a new batch of granules G, so that the process from Figure 10 can start again at step S1.

Claims

Claims 1. Method for batch-wise dedusting a granulate (G) by means of a dedusting device (10), whereby the dust adhering to the granulate grains is removed, the method comprising the following steps: (51) Filling a dust collection container (12) with granules (G), (52) a first dedusting of the filled granules (G) in the dedusting container (12) by means of introduced gas, which is introduced into the dedusting container (12) via a swirling unit (22) comprising nozzles (22b) and / or an annular gap (22a), wherein a main flow direction of the gas introduced into the dedusting container (12) via the swirling unit (22) is substantially opposite to the force of gravity acting on the granules (G), so that the granules (G) are thereby lifted and swirled up and the dust adhering to the granule grains is loosened and discharged from the dedusting container (12) via a gas outlet (20), (53) a second dedusting of the filled granules (G) in the dedusting container (12) by means of introduced gas, in particular air, which is introduced into the dedusting container (12) via a granule outlet opening through which the granules (G) can be conveyed by gravity into an intermediate granule container (26), wherein the gas introduction via the granule outlet opening is caused by a negative pressure which is generated downstream of the gas outlet (20), wherein a main flow direction of the gas introduced into the dedusting container (12) via the granule outlet opening is substantially opposite to the force of gravity acting on the granules (G), wherein the gas flow is strong enough to prevent the majority of the granules from falling through when the granule outlet opening is open, so that the granules (G) are thereby lifted and agitated and the Dust adhering to granules is dissolved and discharged from the dust collection container (12) via the gas outlet (20); and (S4) Emptying the dedusted granules (G) from the dedusting container (12).

2. Method according to claim 1, wherein the gas used in the first dust removal comprises an ionized gas, in particular ionized air, which is preferably mixed in the dust removal container (12), in particular by a lateral inflow.

3. Method according to one of the preceding claims, further comprising blowing out (S6) the dust collection container (12) after emptying the granules (G) from the dust collection container (12), preferably by means of the swirling unit (22).

4. Method according to one of the preceding claims, further comprising a first (S5) and / or second (S7) ion rinsing of the dust collection container (12) after emptying the granules (G) from the dust collection container (12) and before or after blowing out the dust collection container (12), preferably using the swirling unit (22).

5. Method according to one of the preceding claims, further comprising a final cleaning (S8) after emptying the granules (G) from the dust collection container (12) and optionally after blowing out and / or first and / or second ion rinsing by vacuuming the dust collection container (12).

6. Method according to one of the preceding claims, wherein the volume flow rate of the gas introduced during the first dust removal is less than 1000 l / min, preferably less than 600 l / min, and more preferably less than 400 l / min.

7. Method according to one of the preceding claims, further comprising adjusting the airflows for the first and second dust removal and optionally cleaning and / or conveying the granules (G) into the dust removal container (12).

8. Method according to any of the preceding claims, wherein a batch of granules (G) to be dedusted comprises less than 500 ml, preferably less than 400 ml of granules.

9. Dust removal device (10) for carrying out a method according to one of the preceding claims, comprising: a dust removal container (12) with a granule inlet opening (14), a granule outlet opening arranged in a lower region thereof, a gas inlet (18) and a gas outlet (20), which is configured to receive granules (G) to be dusted; a swirling unit (22) comprising nozzles (22b) and / or an annular gap (22a) and configured to introduce a gas into the dust removal container (12) such that a main flow direction of the gas introduced into the dust removal container (12) via the swirling unit (22) is substantially opposite to the force of gravity acting on the granules (G); a granule intermediate container (26) which is arranged below the granule outlet opening and has an air inlet;an airflow generator configured to generate a gas flow from the gas inlet (18) to the gas outlet (20); and a control unit (32) which supplies the swirling unit (22), the airflow generator, and preferably an ejector suction lance (34), an ionizer (52), and / or a sealing element with pressurized gas and evaluates signals from a level sensor (40) to carry out a method according to one of the preceding claims.

10. Dust removal device (10) according to the preceding claim, wherein the dust removal container (12) is tapered downwards towards the granule outlet opening, in particular is tapered conically, and / or wherein the dust removal container (12) is designed to be selectively closable on its underside.

11. Dust removal device (10) according to one of claims 9 and 10, wherein the gas outlet (20) is arranged in an upper region (12a) of the dust removal container (12), in particular a ceiling thereof, wherein the gas outlet (20) is preferably spanned by a screen (42).

12. Dust removal device (10) according to one of claims 9 to 11, further comprising an ionizer (52) which is associated with the dust removal container (12) and preferably comprises a pressurized gas supply opening.

13. Dust removal device (10) according to one of claims 9 to 12, further comprising a granule conveying unit which is configured to feed the granules (G) to be dust-dedusted from a storage container (36) through the granule inlet opening (14) into the dust removal container (12), in particular by means of a conveying air stream, preferably a conveying air stream that can be controlled with respect to its strength and / or duration.

14. Dust extraction device (10) according to one of claims 9 to 13, wherein the dust extraction container (12) has a volume of less than 3000 cm³ 3 has a surface area of ​​preferably less than 2200 cm² 3 ; and / or the inner diameter of the dust collection container (12) is less than 125 mm, preferably less than 100 mm, more preferably less than 70 mm; and / or A circumferential wall of the dust collection container (12) is formed, at least in sections, as an upright, rotationally symmetrical glass tube open at the top and bottom.

15. Dust collection device according to one of claims 9 to 14, wherein the diameter of the granule outlet opening is less than 50 mm, preferably less than 40 mm, and more preferably less than 28 mm.

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