EP2698328B1 - Method for controlling the pressure of air of a fluidising area of a silo, method of retrofitting the control of the pressure of air of a fluidising area in a silo and corresponding silo - Google Patents

Description

The present invention relates to a method for controlled discharge from a silo, as well as a retrofitting method for corresponding silo and a corresponding silo.

Silos for storing and / or metering of fluidisierfähigem bulk having at least one Austragung favoring and / or effecting Fluidisierungsbereich and at least one Austragungsweg, the Fluidisierungsbereich is coupled to the supply of compressed air to a compressed air source, are known from the prior art numerous see, for example DE 3716047 or DE 10251634 , Also known are methods for discharging from such a silo.

With regard to such silos, different designs are known. To mention here are, for example, silos with central extraction or even those with a central cone and decentralized withdrawal from the silo chamber, for example in the region of the cone.

In addition, multi-chamber silos are known.

Even within the solutions with central cone there are different solutions, it is known, for example, to provide at the edges of the cone deductions, in particular outlet pipe with downstream lines and so deducted at different points at the boundary of the cone from the silo. It is also known to provide openings in the lower region of the cone and to allow the material stored in the silo to flow into the cone and to withdraw therefrom.

Although the fluidizable bulk material basically slides by itself, with an appropriate material or corresponding size of silo an automatic discharge is not or only insufficiently possible. Therefore, usually the discharge is supported and deducted the fluidisierfähige bulk material. For this purpose, fluidization systems are provided in floor areas.

In solutions in which outlet nozzles are provided with downstream lines at the boundaries of the cone, are often Fluidisierungsbetten in the vicinity of the outlet nozzle in the actual silo and possibly also in the form of leading away from the discharge opening lines outside of the actual silo.

In solutions in which openings are provided in the lower region of the cone, usually fluidization devices are located both in the silo, ie outside the cone, and inside the cone. Here partially two compressed air circuits are provided, which are separated from each other.

In addition, it is also known that these are not used at the same time, in particular at low discharge rates, in various withdrawals / outlets, but to control these in a temporal pattern one after the other and thus to empty silos alternately by different drawdowns.

Moreover, if openings are provided in the lower region of the cone and fluidization devices are present both in the silo and in the cone, it is also known to turn them on and off differently. For example, it is also known to measure the pressure in the compressed air supply line of the fluidization beds within the cone, since this correlates with otherwise identical circumstances to the filling level of the bulk material within the cone. In this way, for example, the Fluidisierungsbereich outside the cone can only be controlled or embroidered with compressed air when the bulk material level falls within the cone below a preset value or the pressure in the Compressed air supply to Fluidisierungsbereich within the cone falls below a certain value. If it rises above a certain value, the fluidization can be turned off outside the cone.

Due to various effects, however, in such silos there is an increased energy requirement for discharging and damaging both the silo wall and the discharge means. This is based on various effects that are due to the substantially unregulated discharge.

Thus, it is an object of the invention to provide a method or a silo with appropriate devices or a retrofit method for such that allows a largely controlled discharge and thereby reduce both the wear on the discharge means and the negative effect on the silo walls, as well as energy savings , This is achieved by a method according to claim 1 or 12 and a silo according to claim 13. The dependent claims 2 to 11 and 14 to 15 indicate advantageous developments.

To solve the problem, the inventors have found that, for example, used for discharge dosing and downstream lines damage due to the unregulated fluidization and the consequent air flow through the discharge means damage. In addition, resulting in the discharge trash damage to the silo wall and the Austragungsmittel. In addition, it can lead to bridging in the bulk material and thus cause vibrations. All this requires increased wear of the silo or the discharge devices. The modifications of the invention can not only be reduced or avoided, but at the same time the energy consumption can be reduced. Because of the means according to the invention, for example, the wear on dosing systems and downstream lines in the discharge means is also caused by a reduced use of energy.

According to the invention, according to claim 1, providing at least one Austragungsweges the compressed air source, with the at least one favoring the Austragung and / or effecting Fluidisierungsbereich is fed, made controllable and a control of the pressure of the compressed air carried out such that the pressure of the compressed air is measured as feedback variable of the control and the compressed air source is controlled as an actuator of the control so that the pressure of the compressed air regulated to a desired pressure is, wherein the target pressure is selected depending on the discharge rate and / or the position of a provided in the Austragungsaustragungsdurchflussreglers the bulk material.

The compressed air source may be different devices. Usually compressors, in particular forced air compressors with a fixed amount of air, are used here. As actuators are also different means in question. Thus, for example, the speed of a compressor can be changed or worked with appropriate valves, flow controllers or pressure limiters. In particular, however, the compressed air source is chosen so that it is directly controllable in their generation and / or release and the actuator does not work on a discharge of too much generated compressed air. Particularly preferred here is a speed control of a compressor, in particular by frequency conversion.

The measurement of the pressure of the compressed air for feeding the Fluidisierungsbereiches can be effected at different locations and by different means. In particular, pressure measuring sensors can be used here, which can be arranged, for example, in the region of the supply line to the at least one fluidizing region. However, they can also be arranged within the fluidization area itself or at the compressed air source. The control per se can also be carried out differently, for example, a PID control with different proportional, integral and differential shares is conceivable. But also a multi-point control, for example, with a predetermined Druckunter- and upper limit and switching on and off the compressed air source are conceivable. In this context, however, it should be noted that here a control of the pressure of the compressed air is performed, the pressure is measured and it is not, as known from the prior art, to different compressed air circuits.

The choice of the desired pressure can be carried out in different ways. For example, it may depend on the hauling throughput. The discharge throughput is the amount of bulk material that is discharged from the silo per unit of time. In a multi-chamber silo, the discharge throughput is advantageously determined per chamber. In addition, the target pressure may alternatively or additionally be selected as a function of the position of a discharge flow regulator of the bulk material provided in the discharge path. As Austragungsdurchflussregler come here for example metering or the like in question, whose position usually defines an opening cross section of a Austragungsweges or changed. In particular, a discharge flow controller is understood as meaning those means which change the discharge throughput and do not contain any control loop but instead change the discharge throughput in the form of an actuator.

It is preferred to change the target pressure if the discharge flow rate is to be changed or the position of a discharge flow regulator is changed.

In addition, the control can also take into account further input variables. For example, the level of the silo, the type of bulk material, its moisture, the distribution of the bulk material in the silo and / or the temperature can be taken into account.

In accordance with claim 2, the discharge throughput can be a predetermined discharge throughput, which is predetermined directly by the personnel or other decision-making components, for example. Such a specification can also influence, for example, the position of a discharge flow controller.

Alternatively or additionally, according to claim 3, the discharge rate may also be a measured discharge rate. Such a measurement can be realized for example by a balance and a time measurement. Also flowmeters are conceivable. For example, below the load to be loaded Trucks are mounted on a scale and based on this a discharge throughput indirectly determined by the weight gain of the truck. Also, a plurality of measuring devices, in particular in parallel Austragungswegen, combined, in particular additive.

Preference is given in this context to the provision of a balance below a silo, by which the discharge throughput is determined.

Preferably, according to claim 4, a change of the target pressure based on a difference of a predetermined discharge rate and a measured discharge rate. As a difference, the difference between a predetermined discharge throughput and a measured discharge throughput or a variable derived therefrom can be used here. With regard to a measured or predetermined discharge throughput, the above applies.

Particularly preferred is a control in which, when selecting a predetermined Austragungsdurchsatzes and / or a change in a Austragungsweg Austragungsdurchflussreglers the bulk material, in particular a Dosierschiebers, the target pressure is set to a target input pressure and the target pressure in the course at a constant predetermined discharge rate and / or unchanged discharge flow controller based on a difference of the / a predetermined discharge rate and a measured discharge throughput, in particular a difference or a value derived from a difference, is changed. Favor is thereby a control of the target pressure at which a difference between the predetermined Austragungsdurchsatzes and the measured Austragungsdurchsatz is used as a feedback variable and the target pressure is changed as an actuator so that is controlled on a difference or a difference that is minimized.

In particular, increasing the target pressure at a measured discharge rate lower than the predetermined discharge rate is preferred. In particular, a reduction of the target pressure at a measured Discharge throughput higher than the given discharge throughput is preferred.

It is also preferred to initially open at least one, in particular all, in the discharge path of the bulk material provided Austragungsdurchflussreglers wide, in particular to 70 to 100% of its maximum opening at a specification of a Austragungsdurchsatzes. In general, a wide opening of at least one, in particular all, in the used discharge path of the bulk material provided Austragungsdurchflussreglers, in particular to 70 to 100% of its maximum opening, during the discharge is preferred.

Advantageously, according to claim 5, the at least one fluidization region is arranged at the bottom of the storage and / or metering silo. It is advantageously arranged outside a cone.

It is further preferred according to claim 6, the bulk material when passing the at least one Austragungsweges first lead through an outlet and fall from there into a Austragungsdurchflussregler and / or slide and in particular to relax between entry into the outlet nozzle and Austragungsdurchflussregler the bulk material. By such a method, a particularly energy-saving and gentle discharge can be effected.

In this case, a relaxation can take place, for example, by a change in the cross section of the region between entry into the outlet connection and entry into the discharge flow regulator or the discharge flow regulator.

With particular advantage, the method according to claim 7 is carried out such that, depending on the discharge throughput and / or depending on the position of a discharge flow regulator provided in the discharge path, one of at least two reserved control characteristics is used for the control. For example, in areas of low discharge rates, a different control characteristic can be used than, for example, in areas of high discharge throughputs. Also, different control characteristics for other circumstances, for example depending on the filling of the silo or the distribution of the bulk material within the silo held and used accordingly.

With particular advantage, a survey of the height distribution of the bulk material is carried out over the surface of the bulk material in the storage and / or the dosing silos and taken into account in the scheme. Such a measurement of the height distribution of the surface over the surface of the bulk material in the storage and dosage silo, ie the creation of a corresponding height profile, for example, by optical detection means, in particular in the infrared range, for example an IR camera or an IR scanner, performed. Other means for determining a corresponding height distribution, for example by ultrasound or laser are also known in the art and can also be used. By such a detection of the height distribution and consideration of these in the control can be carried out a particularly gentle discharge. As a result, for example, the size of the resulting trumpets can be reduced. This in turn leads to reduced energy consumption for discharging and less stress on the silo walls. The control can be carried out in such a way that a uniform filling level or a reduction of Tromben is achieved. For example, a discharge at the location of the highest level can be performed.

With particular advantage is carried out according to claim 9, a measurement of the height distribution of the bulk material over the surface of the bulk material in the warehouse and dosing silo and is carried out based on the measurement control of the filling. With respect to the survey applies to claim 8. The control of the filling can be carried out for example by selecting different filling openings. The control of the filling also causes a more uniform stress on the silo and can also reduce the formation of droplets or reduce their size.

With particular advantage, the discharge takes place at several provided Austragungswegen from the warehouse and / or dosing silo so that the discharge at the same time always carried out only via a Austragungsweg and / or a discharge nozzle and the sequence of using the Austragungswege / outlet pipe is carried out in particular on the basis of a survey of the height distribution of the bulk material over the surface of the bulk material in the warehouse and / or dosing silo. As a result, the load on the silo wall can be further minimized and the energy required for discharge can be reduced. This can be done, for example, by stopping the discharge via a discharge path and / or an outlet connection after a certain time or after a certain amount of discharge or based on a change in the height distribution and then continuing or starting via another discharge path / outlet connection.

With particular advantage, the discharge is carried out in accordance with claim 11 with the provision of open and ventilated Fluidförderrinnen for discharge with both sides adjacent and in the direction of Fluidförderrinne downwardly sloping fluidization beds such that during a discharge each only a single open and ventilated Fluidförderrinne and only one of both sides of the Fluidförderrinne adjacent Fluidisierungsbetten is operated by charging with compressed air of the compressed air source and in particular for further discharge after a predetermined Austragungsmenge or period when changing the height distribution, the feed of the Fluidisierungsbetten is terminated with compressed air and subsequently during further discharge with respect to the other open ventilated Fluidförderrinnen is also moved, in particular, adjacent fluid conveyors will not be driven directly in succession for removal n.

The object is also achieved by a method for retrofitting a compressed air control in a silo for storing and / or metering of fluidisierfähigem bulk material, comprising at least one the Austragung favoring and / or effecting fluidization area and at least one Austragungsweg, wherein the fluidization area is fed with compressed air of a compressed air source wherein the method includes the installation of a control unit having at least one default input for setting a target pressure, an input variable input for the supply of an input variable and a control output and wherein the method further includes the supply of a pressure signal correlated to the compressed air pressure in the input variable input and supply of the control output to the actuator of an actuator at the compressed air source and supplying a on a discharge throughput and / or the position of a provided in the Austragungsaustragungsdurchflussreglers based signal in the default input.

By such a retrofit method, the advantages of the invention can be realized in a simple manner in existing silos. With regard to the advantageous embodiment and in particular also with regard to the control and the process control, the same applies with regard to the preceding claims or in these. The method includes according to the invention, if individual process steps require further, such as the provision of a measuring unit for generating the measuring signal or the provision of an actuator of a compressed air source in particular also these processes. For the process steps of the discharge, control units that are set up to carry out and / or control the method steps can be provided.

The object is also achieved by a silo for storing and / or metering of fluidisierfähigem bulk material having at least one Austragung favoring and / or effecting Fluidisierungsbereich and at least one Austragungsweg, the Fluidisierungsbereich is coupled to the supply of compressed air to a compressed air source, wherein the compressed air source is controllable and a control unit is provided which includes a default input for specifying a target pressure, an input variable input for the supply of an input variable and a control output and wherein a measuring device for measuring the pressure of the compressed air is coupled to the input variable input and the control output is coupled to the compressed air source , wherein the default input is coupled to a Austragungsdurchsatzermittlungs- and / or default unit and / or with a Austragungsdurchflussregler. With regard to the individual devices or the process control, which is particularly advantageous, particular attention is paid to the preceding claims and the related explanations. All corresponding advantageous procedural features can be realized by providing appropriate means in a silo according to the invention. In particular, corresponding control units are provided which are set up to perform or control the corresponding method steps.

With particular advantage according to claim 14, the at least one Austragungsweg a in the region of the silo wall, in particular the wall between silo and cone, arranged outlet nozzle and in particular a Austragungsdurchflussregler is disposed below the outlet nozzle. By such an arrangement, a particularly efficient and gentle discharge can be carried out, which in particular also exploits gravity as far as possible for discharge.

With particular advantage, according to claim 14, a local rejuvenation of the discharge path is provided between entry into the outlet connection and discharge flow regulator. In particular, such a taper is provided, which leads to a relaxation of the bulk material. Such a rejuvenation can be shaped in various ways. In particular, edges are to be avoided. For example, semi-elliptical projections may be provided in the discharge path.

Fig. 1

eine Ansicht eines Silos;

Fig. 2

eine schematische Darstellung der Regelung;

Fig. 3

eine Ansicht auf eine Schüttgutoberfläche;

Fig. 4

einen Querschnitt durch einen Teil eines Silos;

Fig. 5

eine Aufsicht auf einen Bereich eines Silobodens.

Further advantageous embodiments and positive effects are to be shown purely by way of example and not exclusively with reference to the purely schematic figures. The figures show:

Fig. 1

a view of a silo;

Fig. 2

a schematic representation of the scheme;

Fig. 3

a view of a bulk material surface;

Fig. 4

a cross section through a part of a silo;

Fig. 5

a view of an area of a silo bottom.

Fig. 1 shows a partially released silo. Evident is the surrounding Silowand 1 and a central cone 2. Below the silo located in the storage area a driveway 4 is shown, through which the driving of the interior space for filling of trucks, for example, is possible. In the interior of the silo, in addition to the cone 2, the silo bottom 20 can be seen, which partially has a fluidization region 7. Furthermore, can be seen outlet pipe 19 through which the discharge takes place from the silo. It can also be seen that the silo bottom 20 slopes down to the outlet connection 19.

Fig. 2 shows a diagrammatic illustration of the silo and the devices or method according to the invention, which are divided into two parts for illustration purposes. In the upper area is shown a cross section through a silo. In the lower area is shown the top view of the silo bottom 20 of the silo shown above. In addition, shown are corresponding line arrangements and other elements, but which can be integrated within the silo and are usually. They have been presented in this manner for illustrative purposes only.

To recognize in the upper area is a silo with silo walls 1. It is partially filled with bulk material 3 and has a central cone 2. In the lower part of the cone 2 arranged in the vicinity of the silo bottom 20 are outlet nozzle and then proceed metering 6. They are part of the route of the delegation 9. In this case, the route 9 allows for two different goals. On the one hand, the filling of a truck is shown here. On the other hand, it is discharged into a conveyor system which includes a flow meter 10. In the bottom space below the silo, which can be driven on and does not represent the silo bottom 20, a balance 5 is included, through which the filling of the truck shown can be measured and based on their measurements, a Austragungsdurchsatz can be determined in the truck. Thus, by adding the discharge rates to the truck and through the flow meter 10, the total discharge throughput from the silo can be determined. This is led into a control unit. Also measured is the position of the metering slide 6, via which information is also fed to the control unit 11. Further shown is IR scanner 21 for creating a Surface image or the determination of a Füllhöhenverteilung over the surface of the bulk material 3. This information is also performed in the control unit 1 1. In addition, a compressor 14 with motor 15 and associated frequency converter 16 for the actuating control of the motor 15 is shown in the lower area. In addition, a pressure measuring device 17, the measurement results of which are also fed into the control unit 11, is shown. From the control unit 11 is led out as a control variable, the control for the Freuqenzumrichter 16th

In addition, it can be seen lines that connect the compressor 14 with the fluidization regions 7 in the Silobodenbereich 20. Arranged in between are controllable valves 18, through which individual fluidizing areas can be ventilated separately.

Thus, via the control unit 11 and the frequency converter 16, the amount of air discharged from the compressor 14 can be regulated. By the pressure measuring device 17 of the resulting pressure of the compressed air is determined based on this size and the information about the position of the metering slide 6 and the discharge throughput, a regulation of the pressure of the compressed air can be performed. As a result, for example, at low discharge rates, the amount of compressed air can be significantly reduced, thereby not only saving energy but also preventing damage to the discharge path 9. Because only comparatively small amounts are discharged and is still working at compressed air volumes for the maximum discharge throughput, the rather low Austragungsmengen come with a lot of compressed air together in the Austragungsweg and thus often cause severe wear or damage in Austragungsweg 9, for example in the metering 6th or in downstream pipes.

Fig. 3 shows a view of bulk 3 in a silo. To recognize is a silo wall 1 and the bulk material located therein 3. The surface of the bulk material 3 is not flat, but forms so-called Tromben 22 or flow funnel. Such height distributions can be achieved by a corresponding surface measurement be recognized. As a result, the size, in particular the diameter, of the trumpets 22 can be determined and the discharge and / or filling can be oriented thereon.

Fig. 4 shows a detailed view as a section through the silo. Evident is a silo wall 1 and a cone 2. Also shown is a silo bottom 20 having arranged thereon Fluidierungsbereich 7. In the area of the silo bottom 20 on the wall of the cone 2 is an outlet nozzle 19 can be seen. From there, the discharge path leads into a discharge pipe 8. It can be seen that the further discharge is carried out below the discharge nozzle 19 and, in particular, the metering slide 6 is arranged below the discharge nozzle 9. Thus, the bulk material can be brought out of the outlet nozzle by gravity in the spreader tube 8 or fall or slip.

Fig. 5 shows a section of a plan view of a silo bottom 20 and a cone 2. To recognize a discharge nozzle 19 and fluidization beds 13. A Fluidförderrinne 12 and the Fluidisierungsbetten 13 form a Fluidisierungsbereich. On both sides of the fluid conveying grooves 12, two rows of fluidization beds 13 are arranged. The inclination of the silo floor can be based on Fig. 1 be understood. The silo bottom 20 is inclined in each case down to the fluidization channel 12 down. Also, the fluidization groove 12 is inclined in the direction of the outlet connection 19 downwards.

For removal, different fluidization beds 13 and fluidization channels 12 can now be actuated. However, it is preferred to control only one fluidization channel 12 and the two rows of fluidization beds 13 located on one side of the respectively controlled fluidization channel 12. Advantageously, only fluidization beds 13 are associated which are assigned to a fluidization channel and are arranged on one side of the fluidization channel 12. In this case, the assignment takes place in that the fluidization beds 13 or the silo bottom 20 are inclined downwards in this area in the direction of the fluidization channel 12.

Further advantageous embodiments can be found adapted by the person skilled in the respective application. <B> LIST OF REFERENCES </ b> 1 silo wall 12 Fluid delivery channel 2 cone 13 Fluid conveyor bed 3 bulk 14 compressor 4 entrance 15 engine 5 Libra 16 frequency converter 6 metering 17 Pressure measuring device 7 fluidization 18 Valve 8th discharge pipe 19 outlet connection 9 carry-out 20 silo 10 Flowmeter 21 IR scanner 11 control unit 22 Trombe

Claims (15)

1. A method for controlled extraction through at least one extraction path (9) of fluidisable bulk material (3) from a storage and/or dosing silo, comprising at least one fluidising area (7) promoting and/or actuating the extraction, whereas the fluidising area (7) is fed with compressed air from a source of compressed air (14,15,16), whereas the source of compressed air (14,15,16) is controllable, characterised in that the pressure of the compressed air is regulated, at which the pressure of the compressed air is measured as a return value (17) and the source of compressed air (14, 15, 16) is regulated as a control member in such a way that the pressure of the compressed air is adjusted to a set-pressure, whereas the set-pressure is selected depending on the extraction yield and/or the position of an extraction flowrate regulator (6) of the bulk material (3) provided in the extraction path.
2. The method of claim 1, characterised in that the extraction yield is a predetermined extraction yield.
3. The method of claim 1, characterised in that the extraction yield is a measured extraction yield.
4. The method according to one of the previous claims, characterised in that the set-pressure is modified according to a difference between a measured extraction yield and a predetermined extraction yield.
5. The method according to one of the previous claims, characterised in that the fluidising area (7) is arranged at the bottom (20) of the storage and/or dosing silo.
6. The method according to one of the previous claims, characterised in that the bulk material (3) is guided first of all through a discharge column (19) when passing through said at least one extraction path (9) and from then falls into an extraction flowrate regulator (6) and/or slides therein and is relaxed in particular between the inlet into the discharge column (19) and the extraction flowrate regulator (6).
7. The method according to one of the previous claims, characterised in that according to the extraction yield and/or according to the position of an extraction flowrate regulator (6) provided in the extraction path (9), one of at least two regulation characteristics available is used for regulation.
8. The method according to one of the previous claims, characterised in that a measurement (21) of the height distribution of the bulk material (3) is carried out over the surface of the bulk material (3) in the storage and/or dosing silo and is taken into account in the regulation.
9. The method according to one of the previous claims, characterised in that a measurement (21) of the height distribution of the bulk material (3) is carried out over the surface of the bulk material (21) in the storage and/or dosing silo and a control of the filling process is conducted on the basis of the measurement (21).
10. The method according to one of the previous claims, characterised in that several extraction paths (9) from the storage and/or dosing silo are provided and the extraction is carried out at the same time always over an extraction path (9) and the sequence of usage of the extraction paths (9) is carried out in particular on the basis of a measurement (21) of the height distribution of the bulk material over the surface of the bulk material in the storage and/or dosing silo.
11. The method according to one of the previous claims, whereas the fluidising area contains open and ventable fluid conveying channels (12) with fluidising beds (13) tilted downwards, adjoining on both sides and in the direction of the fluidising channels (12), characterised in that during an extraction process, respectively only one open and ventable fluid conveying channel (12) and exclusively one of both fluidising beds (13) adjoining a fluid conveying channel (12) are operated by supplying compressed air of the source of compressed air (14,15,16) and in particular during further extraction after a predetermined withdrawal quantity, time span and/or modification of the height distribution, the supply is terminated and during a further extraction subsequently is run in terms of the other open and ventable fluid conveying channels (12) after one another, whereas in particular neighbouring fluid conveying channels (12) are not actuated immediately after one another for withdrawal.
12. The method for retrofitting a compressed air control unit in a silo for storing and/or dosing fluidisable bulk material (3), comprising at least one fluidising area (7) promoting and/or actuating the extraction and at least one extraction path (9), whereas the fluidising area (7) is fed with compressed air from a source of compressed air (14,15,16), containing the integration of a regulating unit (11) comprising at least one parameter input so as to predetermine a set-pressure, an input value input for supplying an input value and a control output and for supplying a measuring signal correlated to the pressure of the compressed air into the input value input as well as supplying the control output for control member (16) of a control member (16) on the source of compressed air (14,15,16) as well as supplying a signal based on an extraction yield and/or instead of an extraction flowrate regulator (6) provided in the extraction path.
13. A silo for storing and/or dosing fluidisable bulk material (3) comprising at least one fluidising area (7) promoting and/or actuating the extraction and at least one extraction path (1),
    whereas the fluidising area (7) is coupled to a source of compressed air (14,15,16) for supplying compressed air,
    whereas the source of compressed air is controllable, characterised in that a regulating unit (11) is provided, comprising a parameter input so as to predetermine a set-pressure, an input value input for supplying an input value and a control output and that a measuring device (17) is coupled to the input value input for measuring the pressure of the compressed air and the control output is coupled to a control member (16) of the source of compressed air (14,15,16) and that the parameter input is coupled to an extraction yield determination and/or parameter unit (5, 10) and/or to an extraction flowrate regulator (6).
14. The silo according to claim 13, characterised in that said at least one extraction path (9) contains a discharge column (19) arranged in the area of the silo wall (1) and an extraction flowrate regulator (6) is arranged under the discharge column (19).
15. The silo according to claim 14, characterised in that a local tapering of the extraction path (9) is provided between the inlet into the discharge column (19) and the extraction flowrate regulator (6).

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