WO2017137392A1

WO2017137392A1 - Device and method for conveyance of powder materials in hyperdense phase

Info

Publication number: WO2017137392A1
Application number: PCT/EP2017/052637
Authority: WO
Inventors: Geoffrey Petit
Original assignee: Reel Alesa Sas
Priority date: 2016-02-12
Filing date: 2017-02-07
Publication date: 2017-08-17
Also published as: EP3414196A1

Abstract

A Bypass device (1) for conveying a powder material, in particular in a hyperdense phase, comprises a first duct (S1) which is connectable to an upstream duct (T1), an intermediate duct (S3), and a second duct (S2) which is connectable to a downstream duct (T2). The first duct (SI) is in connection with the second duct (S2) via said intermediate duct (S3), such that said powder material is conveyable from said first duct (SI) via said intermediate duct (S3) to said second duct (S2). The first duct (SI) extends at a first angle (a) angularly inclined to the intermediate duct (S3) and the second duct (S2) extends at a second angle (β) angularly inclined to the intermediate duct (S3). The bypass device further comprises at least one air injection device (N1.1, N1.1', N1.1", N2.1, N2.1', N2.1") that is arranged in one of said first and/or said second duct (SI; S2) for supplying gas at a determined pressure value (P1) and/or at a determined flow value (F1) into said first and/or second duct (S1; S2).

Description

TITLE DEVICE AND METHOD FOR CONVEYANCE OF POWDER MATERIALS IN

HYPERDENSE PHASE

TECHNICAL FIELD The present invention relates to a bypass device for conveying a powder material, in particular in a hyperdense phase. It further relates to a system for conveying the powder material comprising the bypass device and an upstream duct and a downstream duct. It also relates to a method of conveying of a powder material to bypass an obstacle. PRIOR ART

Many devices have been studied and developed for conveying powder materials from a supply zone, typically a storage zone for said material in powder form, to the zone to be supplied with said material in powder form. Thereby, the powder materials usually have to be transported over long distances and are likely to hit obstacles such as, e.g. buildings or roads, which have to be bypassed.

Many of these devices, particularly in the field of aluminium industry, relate to the conveyance of the powder material in a hyperdense phase and it is common to bypass such obstacles by changing the levels of the conveyance system. It is well-known in the state of the art that conveyance by means of hyperdense phase systems are based on the ability of some powders with specific characteristics to become "fluidized", a physical state where an ascending flow of gas is used to minimize the adherence between particles and to thus improve its flowability. As such, a common handling system comprises, for example, two chambers separated by a porous fluidization wall. Low pressure air is injected in the lower chamber and flows through the wall to fluidize the upper chamber where the powder is.

EP 1 091 898 Bl discloses a device to bypass an obstacle comprising three ducts that are inserted between two horizontal conveyors of a hyperdense bed conveyor system being adjacent to the obstacle to be bypassed. The horizontal conveyors are situated at the same level as the obstacle and are connected to two of the ducts, which are vertically arranged with respect to said conveyors. Said two ducts are connected to the third duct that is not at the same level as the obstacle. Thereby, a passage above or below the obstacle to be bypassed is created.

A technical challenge associated with such bypass devices relates to the maintenance of the dense phase fluidized flows especially in the vertically arranged ducts. Oscillations can occur which are directly associated with fluctuations of the material flow in the bypass device and which lead to an unstable material flow. Or even a de-fluidization can emerge, which results in a blockage of the powder material especially at the bottom of the vertically arranged ducts. SUMMARY OF THE INVENTION

It is an object of the present invention to provide a bypass device for conveying a powder material, in particular in a hyperdense phase, where the risk for blockage of the powder material is reduced and which enables a stable powder material flow.

This object is achieved by a bypass device according to claim 1.

The present invention further relates to a system for conveying a powder material, in particular in a hyperdense phase, according to claim 17.

The present invention further relates to a method of conveying a powder material, in particular in a hyperdense phase, to bypass an obstacle according to claim 18.

The invention further relates to a retention plate, preferably arranged in said bypass device, to prevent a backflow of the conveyed powder material according to claim 19.

Further embodiments of the invention are laid down in the dependent claims. The invention provides a bypass device for conveying a powder material, in particular in a hyperdense phase, comprising a first duct which is connectable to an upstream duct, an intermediate duct, and a second duct which is connectable to a downstream duct. The first duct is in connection with the second duct via said intermediate duct, such that said powder material is conveyable from said first duct via said intermediate duct to said second duct. The first duct extends at a first angle angularly inclined to the intermediate duct and the second duct extends at a second angle angularly inclined to the intermediate duct. The bypass device further comprises at least one air injection device that is arranged in one of said first and/or said second duct for supplying gas at a determined pressure value and/or determined flow value into said first and/or second duct.

The gas supplied by the at least one air injection device is at a determined pressure value and/or at a determined flow value so as to influence the powder material flow in a desired manner. In particular it is possible to maintain the fluidity of the mixture between the gas and the product to be conveyed. The determined pressure value and/or the determined flow value of the gas supplied by the air injection device is preferably chosen such, that a potential perturbation on the powder material flow is minimized. The result is a stable flow rate of said powder material flow, where the risk of blockage of the powder material in the bypass device is reduced. The bypass device thus permits a reliable and stable conveying of the powder material.

It should be noted here that the determined flow value and the determined pressure value are physical quantities which both relate to the influence of the supplied gas on an additional fluidity of the material to be conveyed. In particular, the determined flow value can be seen as the flow that is needed to fluidize the material, where a particular flow results in the generation of a particular pressure.

The gas supplied by said air injection device is preferably pressurized air. The powder material to be conveyed preferably corresponds to aluminum oxide Α1₂0_3> but however it is to be understood that the conveyance is not limited to the conveyance of this type of powder material. At least one air injection device can be arranged in either the first duct or in the second duct. Alternatively, at least one air injection device can be arranged in the first duct as well as in the second duct. Said at least one air injection device is preferably arranged such that the gas exits substantially in a counter direction with respect to the direction of flow of the material to be conveyed. That is, the air injection device is preferably arranged such, that the gas injection is pointing upwardly within the first duct and/or the second duct, i.e. along a direction extending from the lowest point of interconnection towards the highest point of interconnection between the first duct and the intermediate duct and the second duct and the intermediate duct, respectively. In other words, an injection is not preferred in the direction of flow of the material to be conveyed in the first duct and it is not preferred in a direction counter to the direction of flow of the material to be conveyed in the second duct, respectively. The injection along such a direction, i.e. upwardly, maintains the fluidization and enhances the so-called drag force as it is known from fluidized beds for example.

It is preferred that the first duct and the second duct are arranged at an angle of about 90° with respect to the intermediate duct. Preferably, the first duct and the second duct extend parallel to one another and are located at a distance with respect to each other. Moreover, it is preferred that the first and the second duct are arranged in a vertical way and that the intermediate duct is arranged in a horizontal way situated either above or below the first and second ducts in their installation. In other words, the bypass with its ducts has in this preferred embodiment the shape of an U. The term "duct" is to be understood as a structural element which is enclosed by a cylinder wall and which extends along a middle axis. In principle, said ducts can have any desired cross-section, however, the ducts preferably have a circular cylindrical or a rectangular cross-section. In the context of the bypass device for conveying a powder material in a hyperdense phase, reference is made to the disclosure of EP 1 091 898 Bl. That is to say, the first duct, second duct and intermediate duct can be designed and operated according to the upstream caisson, downstream caisson and intermediate caisson as disclosed in [0031] to [0055] of EP 1 091 898 Bl. Hence, the ducts described herein can be seen as the caissons of EP 1 091 898 Bl, i.e. as channels or chambers, where each channel (or chamber) comprises two sections that are separated by a porous media resulting in a product channel conveying the powder material and in an air channel used for supplying gas via the porous media into said product channel. Further details are provided below with respect to Figure 1.

Said at least one air injection device is preferably arranged in an air injection zone, wherein said air injection zone extends from the lowest point of interconnection between the intermediate duct and the respective duct up to a specific height in the respective duct. Alternatively, it is preferred that said air injection zone extends from the highest point of interconnection between the intermediate duct and the respective duct up to the specific height in the respective duct.

It is preferred that the specific height is between 1/6 and 3/6, preferably about 1/3, of the total height of the first duct and of the second duct, respectively. For example, given that the first duct extends from the lowest region of connection to the intermediate duct over a height of 6 meter, said at least one air injection device is arranged in the first duct about 1 meter above said lowest region of connection to the intermediate duct. Similarly, given that the second duct extends from the lowest region of connection to the intermediate duct over a height of 6 meters, said at least one air injection device is arranged in the second duct about 1 meter above said lowest region of connection to the intermediate duct.

The air injection device may comprise at least one air injection opening configured to spread the gas over the complete cross-section of the first duct and/or of the second duct. For example, in the case of a cylindrically-shaped duct, gas supplied by the air injection device would be spread by the air injection opening such, that the whole cylindrical cross section of the cylindrically-shaped duct is exposed to the gas. This enhances the performance of the system and in particular prevents congestion in the ducts. Said at least one air injection opening is preferably arranged such that the gas exits substantially upwardly within the first duct and/or the second duct, i.e. along the direction extending from the lowest point of interconnection towards the highest point of interconnection between the first duct and the intermediate duct and the second duct and the intermediate duct, respectively.

It is preferred that the bypass device further comprises in addition to said at least one air injection device at least one further air injection device that is arranged in the first and/or second duct for supplying gas at a determined further pressure value and/or at a determined further flow value into said first and/or second duct.

Hence, it is possible that the bypass device comprises at least one air injection device and at least one further air injection device in the first duct or in the second duct, respectively. Alternatively, it is also possible that only the first duct (second duct) comprises at least one air injection device and at least one further air injection device whereas the second duct (first duct) comprises only at least one air injection device . It is particularly preferred that both the first duct and the second duct each comprise at least one air injection device and at least one further air injection device.

It is to be noted here that the bypass device according to the invention may comprise a plurality of such air injection devices, where any information and explanation made herein may refer to all of these air injection devices. However, for the ease of understanding, reference is primary made to the at least one air injection device and/or the at least one further air injection device.

It is preferred that the air injection device and the further air injection device are arranged at a distance with respect to each other, wherein said distance is preferably between 2 to 10 times the diameter of the duct in which the air injection device is arranged or wherein said distance is between 0.5 meter to 1.5 meter, preferably about 1 meter.

For example, a preferred arrangement comprises air injection devices which cover the first third of the first duct and of the second duct, i.e. the first 2 meter in the case of ducts having a height of 6 meter, where the air injection devices are spaced by a distance of 1 meter. This means an air injection device in the first and the second duct at a height of 1 meter and a further air injection device in the first and second duct at a height of 2 meter with respect to the lowest region of interconnection between the respective duct and the intermediate duct. In the direction of powder material flow, the further air injection device is preferably arranged before the air injection device in the first duct and the further air injection device is preferably arranged after the air injection device in the second duct, respectively.

A gas injection flow rate can be associated with the gas supplied through the air injection device and/or through the further air injection device with respect to the cross-section area of the first and of the second duct, respectively, and a minimum bubbling velocity can be associated with said gas injection flow rate per air injection device with respect to the cross-section area of the respective duct. The gas injection flow rate can be between 0.5 times the minimum bubbling velocity and 5 times the minimum bubbling velocity, preferably around 3 times the minimum bubbling velocity.

The minimum bubbling velocity can be defined as the superficial velocity at which bubbles generated in the powder material flow first appear, and which minimum bubbling velocity can be associated with the gas injection flow rate per air injection device with respect to the cross-section area of the respective duct.

That is, the minimum bubbling velocity is associated with the hydrodynamic characteristic of the powder material to handle, which, in the exemplary case of A1₂0₃, is around 8 millimeter per second.

The air injection device and/or the further air injection device are preferably formed from a porous material. Preferably the porous material is a sintered metal.

It is possible that the air injection device and/or the further air injection device is designed with a truncated-cone-shape and is arranged in the center of the first duct and/or of the second duct, respectively. Thus, the air injection opening can be formed in the apex of the cone so as to spread the gas over the complete cross-section of the first duct and/or of the second duct. The air injection device and/or the further air injection device preferably are a spray nozzle. The air injection device and/or the further air injection device preferably have an injection device diameter being about 10 % to 30 %, preferably about 20 % smaller than the diameter of the first duct and/or the diameter of the second duct, respectively. The air injection device and/or further air injection device or its diameter, respectively, is preferably as small as possible in order not to block the first duct and/or second duct while still being able to spread the gas over the complete cross-section of the respective duct. Hence, it is desired to design the air injection device and/or the further air injection device such that it results in a minimal perturbation of the powder material flow. For example, the air injection devices can be designed with a truncated-cone- shape, where the air injection device surface area ("footprint") is minimized. Thereby, a drag force associated with the forces acting opposite to the powder material flow can also be minimized.

It is also preferred that the air injection device and/or the further air injection device is designed as a nozzle pipe, wherein said nozzle pipe extends at least partially into said duct, or wherein said nozzle pipe extends from a side wall of the duct to the opposite side wall of said duct.

The nozzle pipe is preferably arranged perpendicularly with respect to the powder material flow within the first duct and/or the second duct, i.e. the nozzle pipe preferably extends partially or fully from one side wall of the duct to the opposite side wall of the same duct in a plane being parallel to the cross-section area of said duct.

It is preferred that the nozzle pipe has a diameter being smaller than the diameter of the respective duct. That is, the lateral expansion of the nozzle pipe is preferably as small as possible in order not to block the first duct and/or second duct and consequently the powder material flow, while still being able to spread the gas over the complete cross- section of the respective duct. Hence, it is desired to design the nozzle pipe such that it results in a minimal perturbation of the powder material flow.

It is preferred that the nozzle pipe comprises several nozzle openings that are formed on the nozzle pipe along the direction of extension of the nozzle pipe within the respective duct so as to spread the gas over the complete cross-section of said duct, respectively. Hence, in case of an air injection device and a further air injection device being designed as nozzle pipes, the air injection device and the further air injection device can be seen, in the direction of the powder material flow, as two porous, perforated nozzle pipes running spaced from each other and running in parallel with respect to each other across the a partial or the full width of the first duct and/or second duct.

It is also preferred that the air injection device and/or the further air injection device is designed as a nozzle pipe being arranged in a side wall along a vertical direction of the first duct and/or of the second duct, respectively.

That is, said nozzle pipe can extend within the side wall of the first duct and/or second duct in parallel with the direction of the powder material flow within said duct. One advantage that arises from such an arrangement of the nozzle pipe arranged within the side wall of the duct is the resulting minimal perturbation of the powder material flow.

The nozzles of said nozzle pipe are preferably designed with a truncated-cone- shape and comprise nozzle openings formed in the apex of the cone so as to spread the gas over the complete cross-section of the respective duct.

Thereby, in the direction of the powder material flow, the nozzle opening of the further nozzle is preferably arranged before the nozzle opening of the nozzle in the first duct and/or the nozzle opening of the further nozzle is preferably arranged after the nozzle opening of the nozzle in the second duct, respectively.

It is also preferred that a plurality of nozzles and/or a plurality of further nozzles are designed as a nozzle ring, said nozzle ring extending along a circumferential direction of the first duct and/or second duct, respectively. For example, in the case of a cylindrically-shaped duct having a cylinder wall and a circular cylindrical cross-section, said nozzle ring can be of a circular cylindrical shape, too, and being arranged within the cylinder wall and extending in a circumferential direction along the middle axis of said duct. The diameter of the first duct is preferably smaller than the diameter of the second duct, the diameter of the first duct preferably being about 60 % to 90 , more preferably about 70 % to 80 , particularly preferably about 75 % of the diameter of the second duct.

It is preferred that the first duct has a diameter of about 200 to 400 millimeter, preferably about 300 millimeter, and/or that the second duct has a diameter of about 300 to 500 millimeter, preferably around 400 millimeter. However, it is preferred to choose these diameters according to the desired flow of the powder material.

The total height of the first duct preferably equals the total height of the second duct, the total height of the first duct and of the second duct preferably being in a range of about 2 meter to 8 meter, preferably around 6 meter. But it is possible that the total height of these ducts is smaller than 2 meter or larger than 8 meter, respectively.

However, it is also possible that the height of the first duct is larger than the height of the second duct, or that the height of the second duct is larger than the height of the first duct, respectively.

The system for conveying of a powder material, in particular in a hyperdense bed, according to the present invention comprises a bypass device as described above and an upstream duct and a downstream duct, wherein the first duct is connected to the upstream duct and the second duct is connected to the downstream duct.

As has already been mentioned above, it is possible that the first duct, intermediate duct and second duct each comprise a lower and an upper duct being separated from each other by means of a porous wall, where the lower first duct is supplied with gas at a determined first-duct-pressure value, where the lower intermediate duct is supplied with gas at a determined intermediate-duct-pressure value, and where the lower second duct is supplied with gas at a determined second-duct-pressure value, respectively. It is further possible that the upstream duct and the downstream duct each comprise a lower and an upper duct being separated from each other by means of a porous wall, where the lower upstream duct is supplied with gas at a determined upstream-duct-pressure value and the lower downstream duct is supplied with gas at a determined downstream-duct-pressure value, respectively. In this context, it is preferred to select these determined pressure values such, that the conditions for the fluidization of the powder material are met so that the powder material is in the hyperdense phase, i.e. in the form of a hyperdense bed.

However, as mentioned above, the determined flow values have a likewise influence on the fluidity and are therefore preferably selected such, that the conditions for the fluidization of the powder material are met so that the powder material is in the hyperdense phase, i.e. in the form of a hyperdense bed.

For example, the gas supplied by the air injection device into the first duct and into the second duct is associated with a determined flow value and a further determined flow value which are essentially the same. However, it is also possible that said determined flow value and further determined flow value are different flow values.

Hence, the determined pressure value (determined flow value) of the air injection device and/or the determined further pressure value (determined further flow value) of the further air injection device are then selected such, that a homogeneous fluidization of the powder material is ensured and facilitated, which enables a stable powder material flow and minimizes the risk of blockage by the powder material. The method of conveying a powder material, in particular in a hyperdense bed, to bypass an obstacle, in a bypass device according to the present invention as described above comprises the step of supplying of gas at a determined pressure value and/or at a determined flow value into said first duct and/or said second duct through at least one air injection device being arranged in one of said first and/or said second duct, such that an average bubble pressure present in the first duct and/or in the second duct and/or in the intermediate duct is stabilized and fluctuations in the powder material flow are reduced.

Furthermore, in order to minimize or even prevent a backflow of the conveyed powder material from a downstream duct back into a second duct, a retention plate may be provided. This drives the bubble pressure downstream of a conveyor device conveying a powder material and enables the maintaining of a minimum bubble at the downstream main conveyor.

Hence, a retention plate, preferably arranged in a bypass device as described above, can be arranged in the downstream duct in the region of connection with the second duct, said retention plate extending perpendicular to the direction of the powder material flow and protruding partially into said downstream duct so as to provide a barrier against a return of the conveyed powder material from the downstream duct back into the second duct.

Alternatively, in a further invention, it is provided a conveyor device for conveying a powder material, in particular in a hyperdense phase, or a bypass device as described above, where said conveyor device or said bypass device, respectively, comprise a retention plate being arranged in the downstream duct in the region of connection with the second duct. Said retention plate extends perpendicular to the direction of the powder material flow and protrudes partially into said downstream duct so as to provide a barrier against a return of the conveyed powder material from the downstream duct back into the second duct.

For example, in the case of a vertically arranged second duct being connected to a horizontally arranged downstream duct, said retention plate can be arranged at the interconnection between these ducts and extend in the downstream duct, from the lower point of interconnection of the second duct with said downstream duct towards the upper point of interconnection of the second duct with said downstream duct with respect to the powder material flow, partially into said downstream duct.

Said retention plate can therefore be seen as a barrier arranged within the product material flow, which barrier prevents a backflow of the powder material from the downstream duct back into the second duct, and which enables a stable powder material flow, i.e. it supports the maintenance of the powder material flow also in the downstream duct.

It is preferred that the retention plate has a height that equals the height of the powder material flow in the downstream duct.

BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the invention are described in the following with reference to the drawings, which are for the purpose of illustrating the present preferred embodiments of the invention and not for the purpose of limiting the same. In the drawings,

Fig. 1 shows a schematic vertical section through a bypass device according to the invention with an air injection device and a further air injection device according to a first embodiment.

Fig. 2 shows a sketch of part of the bypass device according to Figure 1 with an air injection device according to the first embodiment.

Fig. 3 shows a sketch of part of the bypass device according to Figure 1 with an air injection device according to a further embodiment.

Fig. 4 shows a sketch of part of the bypass device according to Figure 1 with an air injection device according to a further embodiment.

Fig. 5 shows a sketch of part of the bypass device according to Figure 1 with an air injection device according to a further embodiment.

Fig. 6 shows a sketch of part of the bypass device according to Figure 1 with an air injection device according to a further embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

Figure 1 illustrates a bypass device 1 having air injection devices Nl.l, N2.1 and further air injection devices N1.2, N2.2, here in the form of nozzles and further nozzles for supplying gas at a determined pressure, which corresponds here to a modification of a device as it is described, e.g. in EP 1 091 898 Bl.

In particular, Figure 1 displays the bypass device 1 for conveying a powder material, in particular in a hyperdense phase, comprising a first duct SI which is connectable to an upstream duct Tl, an intermediate duct S3, and a second duct S2 which is connectable to a downstream duct T2. The first duct SI is in connection with the second duct S2 via said intermediate duct S3, such that said powder material is conveyable from said first duct SI via said intermediate duct S3 to said second duct S2. The first duct extends at a first angle a of about 90° angularly inclined to the intermediate duct S3 and the second duct S2 extends at a second angle β of about 90° angularly inclined to the intermediate duct S3. All ducts have a cylindrical shape and comprise a cylinder wall Wl, WT, W2, W2', W3, W3' which extends along a middle axis Ml, M2, M3, respectively.

That is, it is shown in Figure 1 hyperdense siphon comprising three distinct potential fluidization ducts: at the inlet, the first duct SI comprising here a lower duct Sl.l supplied with gas at a determined first-duct-pressure value P3 and an upper "duct" SI.2, consisting essentially of a column CI connected at one end to the upper duct T1.2 of the upstream duct Tl and at the other end to the upper duct S3.2 of the intermediate duct S3. In the middle, at a level which can bypass the obstacle, the intermediate duct S3 comparable to a horizontal air pipe, in which a lower duct S3.1 is supplied with gas at determined intermediate-duct-pressure value P5 and in which an upper duct S3.2, connected at its first end to the upper duct SI.2 of the first duct SI, is connected at its second end to the upper duct S2.2 of the second duct S2. At the outlet from the device, the second duct S2 comprises a lower duct S2.1 supplied with gas at a determined second-duct-pressure value P4 and an upper duct S2.2 consisting essentially of a column C2 connected at one end to the upper duct S3.2 of the intermediate duct S3 and at the other end to the upper duct T2.2 of the downstream duct T2. The horizontal ducts Tl and T2 are at the same level in this case, but there is no reason why the upstream duct and the downstream duct should not be at a different height. The length L of the intermediate duct equals here to about 20 meter, which is sufficient in this case to take the powder material to be conveyed beyond the obstacle. If a greater length L is necessary, it is preferable to connect the intermediate duct S3 with other intermediate ducts S3, S"3, etc., identical to S3, such that they have a common upper duct and lower ducts supplied with gas at a potential fluidization pressure P3, P"3, etc. Column CI is filled with alumina over a height hi such that the free level of the said material 2 is higher than the highest point of the air pipes Tl, T2 and S3. Similarly column C2 is filled with alumina over a height h2 such that the free level of the said material 3 is also higher than the highest point of the air pipes Tl, T2 and S3. The pressure difference ΔΡ=Ρ3-Ρ4 is always positive and is achieved when the height of the powder material hi is kept greater than h2. The intermediate duct S3 is lower than the duct on the two horizontal ducts Tl and T2 and the distance hO is here about 6 meters. Therefore in order to leave free passage for e.g. electrolysis service vehicles, it is necessary to pass the alumina 6 meters below the level of the main conveyor over a distance of 20 meters, and then to lift it up by about 6 meters again. The pressure values P3 and P4 are adjusted such that the system remains full of alumina at all times. The pressures P3 and P4 are such that: P3=hl*dl and P4=h2*d2, where dl is the average density of the product in potential fluidization in column CI, and d2 is the average density of the product in potential fluidization in column C2. The density of the fluidized product varies from one column to another, i.e. it is lower when the fluidization pressure is higher. It was observed that the height hi is preferably greater than the height h2, so that the determined first-duct-pressure value P3 will be greater than the determined second-duct-pressure value P4 and that the device will then operate like a hydraulic siphon. The pressures are chosen to be equal to the following values: P3=0.7 bar, P4=0.6 bars and P5=0.65 bar. It is then found that the level hi of the product with medium density 0.85 is about 8.2 meters, whereas h2 is about 7 meters, and the product flows naturally through the hyperdense siphon, going down through column CI, following the intermediate duct S3 and rising again through column C2. A bubble B of gas was formed in the upper part of the intermediate duct S3. This gas bubble is obtained conventionally by penetration of columns CI and C2 into the upper part of the intermediate duct S3.

The bypass device 1 shown here additionally comprises one nozzle Nl. l and one further nozzle N1.2 that are arranged in the first duct SI, as well as one nozzle N2.1 and one further nozzle N2.2 that are arranged in the first duct S2, respectively. The powder material flow is defined as extending from the upstream duct Tl via the first duct SI to the intermediate duct S3 to the second duct S2 into the downstream duct T2, as indicated by the arrows in Figure 1. Hence, in the direction of powder material flow, the further nozzle N1.2 is arranged after the nozzle Nl. l in the first duct SI and the further nozzle N2.2 is arranged before the nozzle N2.1 in the second duct S2, respectively.

The nozzles Nl. l, N2.1 and further nozzles N1.2, N2.2 are arranged in the first duct SI and in the second duct S2 in the region of connection of the respective duct with the intermediate duct S3. Here, the nozzle Nl.l of the first duct SI and the nozzle N1.2 of the second duct are arranged at a height being about 1/3 of the total height HI of the first duct SI and of the total height H2 of the second duct S2, respectively. In each duct SI, S2, the nozzle Nl. l, N2.1 and the further nozzle N1.2, N2.2 are spaced at a distance d with respect to each other. The diameter of the first duct Dl is smaller than the diameter of the second duct D2 and the total height of the first duct HI is larger than the total height of the second duct H2.

For example, in the case of a vertically arranged second duct being connected to a horizontally arranged downstream duct, said retention plate can be arranged at the interconnection between these ducts and extend in the downstream duct, from the lower point of interconnection of the second duct with said downstream duct towards the upper point of interconnection of the second duct with said downstream duct with respect to the powder material flow, partially into said downstream duct. A retention plate R is arranged in the downstream duct T2 in the region of connection with the second duct S2, i.e. at the interconnection between the downstream duct T2 and the second duct S2. The retention plate R extends perpendicular to the direction of the powder material flow and protrudes partially into said downstream duct T2 so as to provide a barrier against a return of the conveyed powder material from the downstream duct T2 back into the second duct S2.

Detailed aspects of the nozzles and the further nozzles are now discussed with reference to Figures 2 to 6. One has to bear in mind that, although these Figures only display one nozzle or a few nozzles, the bypass device may comprise a plurality of these nozzles and one or a plurality of further nozzles. Furthermore, many of the features discussed above with reference to Figure 1 are left away in these Figures to allow a better view, but should nevertheless be seen as comprised in the bypass device.

In these Figures, the nozzles Nl. l, Nl.l', Nl.l ", Nl. l' ", N2.1, N2.1', N2.1", N2.1' " comprise nozzle openings NO configured to spread the gas over the complete cross-section of the first duct SI and of the second duct S2, respectively. Although not depicted, the same holds for the further nozzles N1.2, N1.2', N1.2", N1.2' ", N2.2, N2.2', N2.2", N2.2". Figure 2 shows a nozzle design according to a first embodiment, where the nozzle Nl. l is designed with a truncated-cone-shape having a minimized nozzle surface area ("footprint"), and which is arranged in the center of the first duct SI. The nozzle Nl.l has a nozzle diameter DN that is smaller than the diameter of the first duct SI. Hence, the nozzle is designed such that it results in a minimal perturbation of the powder material flow. A nozzle opening NO is formed in the apex of the cone so as to spread the gas over the complete cross-section of the first duct SI. Although not depicted, at least one further nozzle N1.2 as well as a nozzle N1.2 and further nozzle N2.2 of the same kind can be arranged in the center of the first duct SI and of the second duct S2, respectively.

Figures 3 and 4 depict a nozzle design according to a further embodiment, where the nozzle Ν1. is designed as a nozzle pipe that extends fully across the first duct SI (Figure 3) and only partially into said duct SI. In the former case, the nozzle pipe extends from one side wall Wl of the first duct SI to the opposite side wall Wl' of said duct. In both cases, the nozzle pipe is arranged perpendicularly with respect to the powder material flow within the first duct SI and has a diameter DN, i.e. a lateral expansion, which is smaller than the diameter of first duct Dl. Although the nozzle pipe shown in Figure 3 comprises several nozzle openings NO that are formed on the nozzle pipe along the direction of extension of the nozzle pipe within the first duct SI and the nozzle pipe shown in Figure 4 only comprises one nozzle opening NO, in both cases it is possible that the respective nozzle pipe comprises only one or several nozzle openings, respectively. Although not depicted, at least one further nozzle N1.2' as well as a nozzle N1.2' and further nozzle N2.2' of the same kind can be arranged in first duct S 1 and the second duct S2, respectively.

Figure 5 depicts a nozzle design according to a further embodiment, where the nozzle Nl.l" is designed as a nozzle pipe being arranged in the side wall Wl of the first duct SI and extending along a vertical direction of said first duct. That is, the nozzle pipe extends within the side wall Wl of the first duct SI in parallel with the direction of the powder material flow within said duct. The individual nozzle of said nozzle pipe has a truncated- cone-shape and comprises a nozzle opening formed in the apex of the cone so as to spread the gas over the complete cross-section of the respective duct. Although not depicted, at least one further such nozzle N1.2" can be comprised in said nozzle pipe in the first side wall Wl of the first duct SI and a nozzle pipe N1.2", N2.2" of the same kind can be arranged in the side wall W2 of the second duct S2, respectively.

Figure 6 depicts a nozzle design according to a further embodiment, where a plurality of nozzles Nl. l" 'are designed as a nozzle ring which extends along a circumferential direction of the first duct SI. In this case of a cylindrically-shaped duct SI having a circular cylindrical cross-section, said nozzle ring is of a circular cylindrical shape, too, and is arranged within the cylindrical side wall Wl, Wl' of the first duct S I and extends in a circumferential direction along the middle axis Ml of said duct. Although not depicted, a plurality of further such nozzles N1.2' " can be comprised in a further nozzle ring in the first side wall Wl of the first duct SI, and a nozzle ring with nozzles N1.2" ' and as well as a further nozzle ring with further nozzles N2.2' " of the same kind can be arranged in the side wall W2 of the second duct S2, respectively.

LIST OF REFERENCE SIGNS

1 bypass device

2 free level of material in first duct 3 free level of material in second duct

51 first duct

52 second duct

53 intermediate duct

Tl upstream duct

T2 downstream duct

Wl, Wl' side wall of first duct

W2, W2' side wall of second duct

HI total height of first duct

H2 total height of second duct

hi height of first duct

h2 height of second duct

Dl diameter of first duct

D2 diameter of second duct

D3 diameter of intermediate duct

N, N' air injection zone

ΝΙ.Ι, ΝΙ. Ι',

N 1.1 " , N 1.1 " ' air injection device of first duct

N2.1, N2.1\

N2.1 " , N2.1 " ' air injection device of second duct N1.2, N1.2',

Nl .2" , Nl .2" ' further air injection device of first duct N2.2, N2.2',

N2.2' ' , N2.2' ' ' further air injection device of second duct NO air injection device opening

DN diameter of air injection device

PI pressure value

P2 further pressure value

P3 first-duct-pressure value

P4 second-duct-pressure value

P5 intermediate-duct-pressure value

PD downstream-duct-pressure value

PU upstream-duct-pressure value

PB average bubble pressure

Fl flow value

F2 further flow value

U gas injection flow rate

Umb minimum bubbling velocity

R retention plate

HR height of retention plate

M 1 , M2, M3 middle axis

a first angle

β second angle

d distance between air injection device and further air injection device L spacing between first duct and second duct

Claims

1. Bypass device (1) for conveying a powder material, in particular in a hyperdense phase, comprising:

a first duct (SI) which is connectable to an upstream duct (Tl);

an intermediate duct (S3); and

a second duct (S2) which is connectable to a downstream duct (T2),

wherein the first duct (SI) is in connection with the second duct (S2) via said intermediate duct (S3), such that said powder material is conveyable from said first duct (SI) via said intermediate duct (S3) to said second duct (S2),

wherein the first duct (SI) extends at a first angle (a) angularly inclined to the intermediate duct (S3) and wherein the second duct (S2) extends at a second angle (β) angularly inclined to the intermediate duct (S3),

characterized in that the bypass device further comprises at least one air injection device (Nl. l, Nl. l', Nl.l", Nl. l' ", N2.1, N2.1', N2.1", N2.1' ") that is arranged in one of said first and/or said second duct (SI; S2) for supplying gas at a determined pressure value (PI) and/or at a determined flow value (Fl) into said first and/or second duct (SI; S2).

2. The bypass device according to claim 1, wherein said at least one air injection device (Nl. l, Nl. l', Nl. l", Nl.l' ", N2.1, N2.1', N2.1", N2.1' ") is arranged in an air injection zone (N),

wherein said air injection zone (N, N') extends from the lowest point of interconnection between the intermediate duct (S3) and the respective duct (SI; S2) up to a specific height in the respective duct (SI; S2), or

wherein said air injection zone (N, N') extends from the highest point of interconnection between the intermediate duct (S3) and the respective duct (SI; S2) up to the specific height in the respective duct (SI; S2).

3. The bypass device according to claim 2, wherein said specific height is between

1/6 and 3/6, preferably about 1/3, of the total height of the first duct (SI) and of the second duct (S2), respectively.

4. The bypass device according to any of the preceding claims, wherein the air injection device (Nl.l, Nl.l', Nl. l", Nl. l'", N2.1, N2.1', N2.1", N2.1' ") comprises at least one air injection opening (NO) configured to spread the gas over the complete cross-section of the first duct (SI) and/or of the second duct (S2).

5. The bypass device according to any one of the preceding claims, further comprising in addition to said at least one air injection device (Nl. l, Ν1. , Nl.l", Nl.l' ", N2.1, N2.1', N2.1", N2.1' ") at least one further air injection device (N1.2, N1.2', N1.2", N1.2' ", N2.2, N2.2', N2.2", N2.2' ") that is arranged in the first and/or second duct (S 1 ; S2) for supplying gas at a determined further pressure value (P2) and/or at a determined further flow value (F2) into said first and/or second duct (SI; S2).

6. The bypass device according to claim 5, wherein the air injection device (Nl.l, Nl.l', Nl. l", Nl.l' ", N2.1, N2.1', N2.1", N2.1' ") and the further air injection device (N1.2, N1.2', N1.2", N1.2' ", N2.2, N2.2', N2.2", N2.2'") are arranged at a distance (d) with respect to each other, wherein said distance is preferably between 2 to 10 times the diameter (Dl; D2) of the duct (SI; S2) in which the air injection device is arranged, or

wherein said distance (d) is between 0.5 meter and 1.5 meter, preferably about 1 meter.

7. The bypass device according to claim 5 or 6, wherein, in the direction of powder material flow, the further air injection device (N1.2, N1.2', N1.2", N1.2' ") is arranged before the air injection device (Nl.l, Ν1. , Nl. l", Ν1. ") in the first duct (SI) and the further air injection device (N2.2, N2.2', N2.2", N2.2' ") is arranged after the air injection device (N1.2, N1.2', N1.2", N1.2' ") in the second duct (S2), respectively.

8. The bypass device according to any one of the preceding claims, wherein a gas injection flow rate (U) is associated with the gas supplied through the air injection device (Nl.l, Nl. l', Nl. l", Nl. l'", N2.1, N2.1', N2.1", N2.1'") and/or through the further air injection device (N1.2, N1.2', N1.2", N1.2' ", N2.2, N2.2', N2.2", N2.2" ') with respect to the cross-section area of the first (SI) and of the second duct (S2), respectively,

wherein a minimum bubbling velocity (Umb) is associated with said gas injection flow rate per air injection device with respect to the cross-section area of the respective duct (SI; S2), and

wherein the gas injection flow rate (U) is between 0.5 times the minimum bubbling velocity (Umb) and 5 times the minimum bubbling velocity (Umb), preferably around 3 times the minimum bubbling velocity.

9. The bypass device according to any one of the preceding claims, wherein the air injection device (Nl.l, Nl.l', Nl.l", Nl. l' ", N2.1, N2.1', N2.1", N2.1' ") and/or the further air injection device (N1.2, N1.2', N1.2", N1.2' ", N2.2, N2.2', N2.2", N2.2' ") are formed from a porous material.

10. The bypass device according to any one of the preceding claims, wherein the air injection device (Nl. l, N1.2) and/or the further air injection device (N2.1, N2.2) is designed with a truncated-cone- shape and is arranged in the centre of the first duct (SI) and/or of the second duct (S2), respectively.

11. The bypass device according to claim 10, wherein the air injection device (Nl. l, N1.2) and/or the further air injection device (N2.1, N2.2) have an air injection device diameter (DN) being about 10 % to 30 , preferably about 20 % smaller than the diameter of the first duct (Dl) and/or the diameter of the second duct (D2), respectively.

12. The bypass device according to any one of the preceding claims, wherein the air injection device (Ν1. , N1.2') and/or the further air injection device (Ν2. , N2.2') is designed as a nozzle pipe, wherein said nozzle pipe extends at least partially into said duct (S I; S2); or

wherein said nozzle pipe extends from a side wall (Wl; W2) of the duct (SI; S2) to the opposite side wall (Wl' ; W2') of said duct (SI; S2).

13. The bypass device according to any one of the preceding claims, wherein the air injection device (ΝΊ.Γ ', N1.2") and/or the further air injection device (N2.1", N2.2") is designed as a nozzle pipe being arranged in a side wall along a vertical direction of the first duct (SI) and/or of the second duct (S2), respectively.

14. The bypass device according to any one of the preceding claims, wherein a plurality of air injection devices (Ν1. ", N1.2" ') and/or a plurality of further air injection devices (Ν2. ", N2,2' ") are designed as a nozzle ring, said nozzle ring extending along a circumferential direction of the first duct (SI) and/or second duct (S2), respectively.

15. The bypass device according to any one of the preceding claims, wherein the diameter (Dl) of the first duct (SI) is smaller than the diameter (D2) of the second duct (S2), the diameter of the first duct (Dl) preferably being about 60 % to 90 , more preferably about 70 % to 80 , particularly preferably about 75 % of the diameter of the second duct (D2).

16. The bypass device according to any one of the preceding claims, wherein the total height of the first duct (HI) equals the total height of the second duct (H2), the total height of the first duct (HI) and of the second duct (H2) preferably being about 6 meter.

17. System for conveying of a powder material, in particular in a hyperdense phase, comprising a bypass device (1) according to any one of the preceding claims, and an upstream duct and a downstream duct, wherein the first duct (SI) is connected to the upstream duct (Tl) and the second duct (S2) is connected to the downstream duct (T2).

18. Method of conveying a powder material, in particular in a hyperdense phase, to bypass an obstacle, in a bypass device (1) according to any one of the preceding claims,

characterized in that the method comprises: the step of supplying of gas at a determined pressure value (PI) and/or at a determined flow value (Fl) into said first duct (SI) and/or said second duct (S2) through at least one air injection device (Nl.l, Ν1. Γ, Nl.l", Ν1. Γ", N2.1, Ν2. , N2.1", Ν2. ") being arranged in one of said first and/or said second duct (SI; S2), such that an average bubble pressure (PB) present in the first duct (SI) and/or in the second duct (S2) and/or in the intermediate duct (S3) is stabilized and fluctuations in the powder material flow are reduced.

Conveyor device (1) for conveying a powder material, in particular in a hyperdense phase, or a bypass device according to one of the preceding claims, characterized in that said conveyor device or said bypass device, respectively, comprise a retention plate (R) being arranged in the downstream duct (T2) in the region of connection with the second duct (S2), said retention plate (R) extending perpendicular to the direction of the powder material flow and protruding partially into said downstream duct (T2) so as to provide a barrier against a return of the conveyed powder material from the downstream duct (T2) back into the second duct (S2).