WO2009043073A2

WO2009043073A2 - Method and apparatus for drying pourable material

Info

Publication number: WO2009043073A2
Application number: PCT/AT2008/000354
Authority: WO
Inventors: Werner Wittmann
Original assignee: Wittmann Kunststoffgeräte Gmbh
Priority date: 2007-10-02
Filing date: 2008-10-02
Publication date: 2009-04-09
Also published as: TW200916713A; WO2009043073A3; AT505391A4; AT505391B1

Abstract

The invention relates to a method and an apparatus for drying pourable material in a drying silo (1) by means of an air flow. The used air flow (5) that is discharged from the drying silo (1) or the returning air is dried in a drying cell (6) containing a drying agent or adsorbent and is fed to the pourable material as a dry air flow (3). If necessary, the adsorbent is regenerated in the drying cell (6). The used air flow (5) is fed to a supply duct that is disposed in the drying cell (6) and is connected to the adsorbent, is deflected in the drying cell (6), is conducted across the adsorbent, is then deflected once again as a dry air flow (3), is withdrawn in a discharge duct against the direction of flow in the supply duct, and is fed to the drying silo (1). The drying cell (6) that is designed as a wheel-type drier is rotated in stages or continuously. The drying cell (6) is designed as a drum comprising at least three concentric, axially extending zones (20, 21, 22). The adsorbent is located in the central zone (20), while the two other, external and internal zones (21, 22) are designed as ducts for the used air flow (5) or the dry air flow (3). The ducts are connected to the zone (20) containing the adsorbent in order to allow air to penetrate therebetween.

Description

Method and device for drying bulk material

The invention relates to a method for drying bulk material, in particular solids, such as granules, powders, grains, films, snippets, o. The like., Preferably plastic granules, in a drying silo by means of an air stream, wherein the exiting from the drying silo exhaust air stream or dried the return air in a drying or adsorbent-containing drying cell, optionally regenerating the adsorbent and fed as dry air flow to the bulk material.

Thus, from DE 36 25 013 A1 discloses a method and apparatus for drying bulk material, preferably plastic granules in a drying hopper by means of dry air known. In the course of this procedure the from the

Drying funnel emerging exhaust air dried in a dryer containing an adsorbent and fed back to the bulk material as dry air.

Furthermore, DE 197 57 537 A1 discloses a method and a device for drying and heating air, which is used for drying bulk material. This device essentially consists of at least one drying cartridge or drying cell, a downstream air heater, a downstream drying chamber or drying silo and a downstream cooling device.

Furthermore, from DE 101 18 762 A1 a method for the regeneration of moisture-laden process air is known. The atmospheric air is heated and fed to the drying cartridge to be regenerated. The subsequent re-cooling of the drying cartridge is carried out with a diverted from the dried process air partial air flow. EP 0 712 656 B1 discloses a method for drying moist air, and EP 740 956 A2 discloses a method and a device for processing an adsorbent, in particular moisture.

Moreover, DE 2 025 205 A1 discloses a device with a plurality of chambers for the selective adsorption of molecules.

All of the above-mentioned methods and devices have above all the disadvantages that in the method, a high energy consumption for the regeneration and drying is given and the devices require a very expensive construction.

The object of the invention is therefore to provide a method of the type mentioned, on the one hand avoids the above disadvantages and on the other hand, globally, increases the cost.

The object is achieved by the invention.

The inventive method is characterized in that the exhaust air stream supplied to a provided in the drying cell, connected to the adsorbent supply channel, deflected in the drying cell of the exhaust air flow and passed over the adsorbent and then redirected as a dry air flow again is discharged in a discharge channel opposite to the flow direction in the feed channel and fed to the drying silo. With the invention it is possible for the first time to reduce the energy consumption on the one hand by the countercurrent process and on the other hand by the deflection of the air flow in a, by about 90 ° to the flow direction in the feed, horizontal flow direction a more uniform flow through the adsorbent, also called zeolite or molecular sieve , to achieve.

According to a particular feature of the invention, the drying cell is divided into at least three circle segments, the area of a circle segment for drying or dehumidifying the exhaust air stream, the region of the second circle segment for heating the adsorbent and the region of the third circle segment for cooling the adsorbent is used. By this division into corresponding areas of the drying cell, a minimization of the space required is achieved since the process process interrupting intermediate steps, by lines to the individual process steps omitted. It also optimizes the energy budget of the overall process.

According to a further particular embodiment of the invention, the air duct is performed in the area for the heating and cooling comprehensive, regeneration of the adsorbent according to the air flow in the area for drying or dehumidification. Also for these process steps, the energy-saving variant of the countercurrent air flow is easy to implement and brings a homogenization of the overall process with it.

According to a particular embodiment of the invention, the circle segments of the drying cell are divided with radial partitions into individual sectors or cells. As a result, smaller spatial units are created for the individual process steps, which facilitate an optimization of the overall process.

According to a very special feature of the invention, the drying cell designed as a wheel dryer is rotated stepwise or continuously. This design achieves a more consistent dew point over the operating time, further optimizing the energy balance of the overall process.

According to a particular embodiment of the invention, the drying or dehumidifying phase for the exhaust air flow and the heating or cooling of the adsorbent run in parallel. This advantageously creates a continuous process that requires minimal energy and requires minimal space.

The invention is also based on the object to provide a device for carrying out the method described above, on the one hand to the state of Technique cited disadvantages avoids and on the other hand has a simple structural design effort.

This object is also achieved by the invention. The inventive device for carrying out the method is characterized in that the drying cell is formed as a drum having at least three concentrically arranged, axially extending regions, wherein the adsorbent is provided in the central region and the other two, outside and inside, areas as channels for the exhaust air flow or are designed for the dry air flow and the channels with the

Adsorbent-containing area are connected for an air passage. In connection with the above-mentioned inventive, procedural air flow, there is the advantage that only a compact unit for the various process steps is needed. This plant-technical simplification entails an immensely high economic efficiency, which of course has a very positive effect on the investment sum and also on the operating costs with regard to preservation and service life.

By this embodiment of the invention, the advantage is given that in an operationally necessary exchange of the adsorbent only the

Adsorbent has to be disposed of in a landfill. Of course, the drum housing in which the adsorbent is contained in operation can be reused. An immense advantage in terms of environmental impact is thus given. Furthermore, of course, the cost of such renewal are drastically reduced.

According to one embodiment of the invention, the connection of the individual areas for the passage of air via screen and / or perforated plates takes place. As a result, a uniform flow through the adsorbent can advantageously be achieved since the perforated or perforated plates can be adapted to the corresponding requirements. According to a particular embodiment of the invention, designed as a drum drying cell is provided at one axial end with a bottom and at the other end with a, recesses having, lid. This results in a cost-effective and extremely simple construction of the device.

According to a particular feature of the invention, a connection cap is provided over the lid. The inventive, procedural air flow only one connection cap is necessary.

According to a very special feature of the invention, the drum is designed as a rotating drum, wherein the connection cap is stationary and between the connection cap and rotating drum, in particular the lid, a sealing surface is provided. Due to the necessity of only one sealing surface results in a reduced friction, which has a positive effect on the connection performance. Furthermore, a reduction of the moist false air is observed. A reduction in repair susceptibility is given by the reduction of two sealing surfaces in axial flow according to the prior art systems, on a sealing surface in the countercurrent air guide according to the invention.

According to a further particular feature of the invention, at least one of the two facing surfaces is preferably formed flat for sealing the rotating drum to the connection cap and at least one elastic compensation element is arranged between the facing surfaces. This elastic compensation element serves as a sealing disc and compensates for height and angular irregularities. Distortions and curvatures, which can occur due to the temperature differences, are thereby compensated. Of course, both facing surfaces could be executed plan and each surface be provided with an elastic compensation element.

According to a development of the invention, the three areas with radial partitions into individual sectors, in particular wheel sectors or cells, divided. As a result, smaller, spatial units are available in the process process, whereby a more optimal control or regulation of the overall process is achieved.

According to one embodiment of the invention, the radial partitions are slightly inclined. Apart from advantageous, injection-molding measures of this embodiment, thereby disturbing turbulence o. The like. Can be avoided in the air flow.

According to a special feature of the invention, at least three, preferably six, in particular 36, wheel sectors are provided circumferentially. As a result, a continuous overall process is advantageously possible, wherein an optimal uniform dew point over the operating time is achieved by the small spatial units. Due to the continuously rotating drying cell as a drum, the dead times in the process are practically zero.

According to one embodiment of the invention, the drum is constructed axially from at least one, preferably five, wheel segments. Due to this modular design, the drying cell can be realized in the simplest way according to their requirement profile.

According to a further embodiment of the invention, the adjacent wheel segments or a wheel segment with the lid or the bottom are axially mounted centrally via a tongue and groove connection. This simple constructional design ensures a stable connection of the individual elements and ensures the functionality of the device.

The invention will be explained in more detail with reference to exemplary embodiments, which are illustrated in the drawing.

Show it:

Fig. 1 is a flowchart of the method Fig. 2 is a wheel segment in isometric view and

Fig. 3 is an overall view of the means for performing the method partially in section.

1 schematically shows a process for drying bulk material, in particular solids, such as granules, powders, grains, films, chips, o. The like., Preferably plastic granules, in a drying silo 1 shown. The bulk material is introduced via the material supply 2 in the drying silo 1 and dried by means of an air flow, referred to here as a dry air stream 3, which absorbs the moisture of the material. The dried bulk material is discharged from the drying silo 1 via the material suction box 4 and fed to its use, for example an injection molding machine.

The exhaust air stream 5 exiting from the drying silo 1 or the return air is dried in a drying cell 6 containing an adsorbent or a molecular sieve, also referred to as zeolite layer, and fed back to the bulk material in the drying silo 1 as a dry air stream 3.

The exhaust air stream 5 is fed via a filter 7 and a fan 8, provided in the drying cell 6, connected to the adsorbent or molecular sieve, feed channel, deflected in the drying cell 6 of the exhaust air stream 5 and the adsorbent or The molecular sieve is guided and then redirected as dry air stream 3 again deflected in a discharge channel against the flow direction in the feed channel and fed to the drying silo 1. The two-time deflection is illustrated by the arrow 9. Before introducing the dry air stream 3 into the drying silo 1, it can be heated via a heater 10.

For regeneration of the adsorbent or the molecular sieve, ie for dehumidification, fresh air 14 is supplied via a blower 11, which is preceded by a filter 12 and a heater 13 downstream. The exhaust air 15 after the adsorbent or the molecular sieve is discharged into the open, wherein the heated exhaust air 15 heats the fresh air 14 in the heat exchanger 16. The supplied fresh air 14 is again deflected twice in the drying cell 6 (arrow 17) and led into the open.

After regeneration, ie dehumidification, of the adsorbent or of the molecular sieve, the adsorbent or the molecular sieve is cooled in order to obtain the optimum operating temperature again. For this purpose, a partial air stream 18 is branched off from the exhaust air stream 5 and fed to the adsorbent or the molecular sieve in the drying cell 6. This partial air flow 18 is deflected twice (arrow 19) and fed to the blower 8.

According to this method, the drying cell 6 is divided into at least three circle segments, wherein the area of a circle segment for drying or dehumidifying the exhaust air stream 5, the area of the second circle segment for heating or regenerating the molecular sieve or adsorbent and the area of the third circle segment is used for cooling the molecular sieve or adsorbent.

The drying cell 6 designed as a wheel dryer is rotated stepwise or continuously so that the corresponding process step is carried out continuously in each area. It also follows that the

Drying or dehumidifying phase for the exhaust air stream 5 and the heating or cooling of the molecular sieve or adsorbent run in parallel.

Characteristic of the above method is that on the one hand by the first deflection of the air flow in one, by about 90 ° to the flow direction in

Feed channel, horizontal flow direction a more uniform flow through the molecular sieve or adsorbent, also called zeolite layer, is achieved and on the other hand by the two-time deflection, ie a countercurrent process, the energy consumption is reduced.

Regeneration of the molecular sieve or adsorbent, which is carried out in the region for heating and cooling, is carried out in the drying or dehumidifying area in accordance with the air flow. According to FIG. 2, a section through the drying cell 6 is shown in an isometric view, wherein the shaft (not shown) is provided in the center. The drying cell 6 is designed as a drum, wherein radially at least three concentrically arranged, axially extending portions are provided. In the central region 20, the adsorbent or the molecular sieve is provided and the other two, outside and inside, areas 22 and 21 are formed as a feed channel for the exhaust air flow 5 and discharge channel for the dry air stream 3 , The channels are connected to the adsorbent-containing portion 20 for air passage. The connection of the individual areas 22, 20 and 20, 21 for the passage of air through sieve and / or perforated plates which are arranged axially and are supported on the webs 23.

The three regions 20, 21, 22 are divided by radial dividing walls 24 into individual sectors, in particular wheel sectors or cells. At a

Embodiment are provided circumferentially at least three, preferably six, - in the preferred case shown - 36, wheel sectors.

The dry cell designed as a drum is constructed axially from at least two, preferably five, wheel segments 25. The adjacent wheel segments 25 and a wheel segment 25 with the cover or the bottom are axially mounted centrally via a tongue and groove connection 26.

According to FIG. 3, an overall view of the device for carrying out the method is shown partly in section. A plurality of wheel segments 25 are stacked on top of each other as a drying cell 6 in the form of a drum. At one axial end, a bottom 27 and at the other end a cover 28 which is provided with the corresponding recesses for the air ducts is provided. Above the cover 28, a stationary connection cap 29 is provided. As already mentioned, the drum is designed as a rotating drum, wherein the connection cap 29 is stationary and between the connection cap 29 and the rotating drum, in particular the cover 28, a sealing surface is provided. To seal the rotating drum to Connection cap 29 is at least one of the two surfaces to be sealed flat and between the surfaces at least one elastic compensation element 30 is arranged.

According to the method, the exhaust air stream 5 is fed axially to the drying cell 6 via the region 22 formed as a feed channel, and in the drying cell 6 the exhaust air stream 5 is deflected into the region 20 containing the adsorbent and passed over the adsorbent , Subsequently, the air stream designated after its dehumidification as a dry air stream 3 is again deflected into the region 21 and, in the region 21 designated as a discharge channel, is diverted counter to the flow direction in the feed channel and fed to the drying silo 1. The connections of the connection hood 29 have been designated for better understanding in accordance with the air flows in FIG. From these connections, the individual areas of a circle segment, where the area of a

Circular segment for drying or dehumidifying the exhaust air stream 5, the region of the second circle segment for heating or regenerating the molecular sieve or adsorbent and the region of the third circle segment for cooling the molecular sieve or adsorbent is used.

As already mentioned, it is characteristic of the method and the device that the air ducts in the drying cell 6 are guided in the countercurrent principle, so that there is only one sealing surface between the rotating drum and the stationary connection hood.

Claims

claims:

1. A method for drying bulk material, in particular solids, such as granules, powders, grains, films, snippets, o. The like., Preferably

Plastic granules, in a drying silo by means of an air flow, wherein the outgoing from the drying silo exhaust air stream or the return air dried in a drying or adsorbent-containing drying cell, optionally regenerates the adsorbent and fed as dry air flow to the bulk material, characterized in that the exhaust air stream (5) is fed to a feed channel connected to the adsorbent in the drying cell (6), the exhaust air stream (5) is deflected in the drying cell (6) and passed through the adsorbent and subsequently as a dry air stream (3) again deflected in one

Abführ channel opposite to the flow direction in the feed channel derived and the drying silo (1) is supplied.

2. The method according to claim 1, characterized in that the drying cell (6) is divided into at least three circle segments, wherein the region of a circle segment for drying or dehumidifying the exhaust air stream (5), the region of the second circle segment for heating the adsorbent and the area of the third circle segment is used to cool the adsorbent.

3. The method according to claim 1 or 2, characterized in that the air duct is performed in the region for the heating and cooling comprehensive, regeneration of the adsorbent according to the air flow in the area for drying or dehumidification.

4. The method according to any one of claims 1 to 3, characterized in that the circle segments of the drying cell (6) with radial partitions (24) are divided into individual sectors or cells.

5. The method according to any one of claims 1 to 4, characterized in that the formed as a wheel dryer drying cell (6) is rotated stepwise or continuously.

6. The method according to any one of claims 1 to 5, characterized in that the drying or dehumidification phase for the exhaust air flow (5) and the heating or cooling of the adsorbent take place in parallel.

7. Device for carrying out the method according to one of claims 1 to 6, characterized in that the drying cell (6) is designed as a drum with at least three concentrically arranged, axially extending regions (20, 21, 22), wherein in the central region ( 20) the adsorbent is provided and the other two, outside and inside, areas (21, 22) as channels for the exhaust air flow (5) and for the dry air stream (3) are formed and the channels with the

Adsorbent-containing area (20) are connected for an air passage.

8. A device according to claim 7, characterized in that the connection of the individual areas for the passage of air through perforated and / or perforated plates.

9. Device according to claim 7 or 8, characterized in that the drum formed as a drying cell (6) at one axial end with a bottom (27) and at the other end with a, recesses, cover (28) is provided.

10. Device according to one of claims 7 to 9, characterized in that on the cover (28) has a connection cap (29) is provided.

11. Device according to one of claims 7 to 10, characterized in that the drum is designed as a rotating drum, wherein the connection cap (29) is stationary and between connection cap (29) and rotating drum, in particular the cover (28), a sealing surface is provided.

12. The device according to claim 11, characterized in that for sealing the rotating drum to the connection cap (29) preferably at least one of the two facing surfaces is flat and between the facing surfaces at least one elastic compensation element (30) is arranged.

13. Device according to one of claims 7 to 12, characterized in that the three regions (20, 21, 22) with radial partitions (24) are divided into individual sectors, in particular wheel sectors or cells.

14. Device according to one of claims 7 to 13, characterized in that the radial partitions (24) are slightly inclined.

15. Device according to one of claims 7 to 14, characterized in that circumferentially at least three, preferably six, in particular 36, wheel sectors are provided.

16. Device according to one of claims 7 to 15, characterized in that the drum is constructed axially from at least one, preferably five, wheel segments (25).

17. Device according to one of claims 7 to 16, characterized in that the adjacent wheel segments (25) or a wheel segment (25) with the cover (28) or the bottom (27) axially via a tongue and groove connection (26). are stored centrally.