Drying device for polymer granules

Abstract

The invention relates to a trickling device (10) for a particulate material, the trickling device (10) having a feed region (20), a middle region (30), and a dispensing region (40), the feed region (20) being arranged above and directly adjacent to the middle region (30), the middle region (30) being arranged above and directly adjacent to the dispensing region (40), the trickling device (10) having an outer wall (50), the middle region (30) having a first axis of symmetry (60), a first body (70) being arranged at least in the middle region (30), the first body (70) extending over the entire length of the middle region (30), the first body (70) having a second axis of symmetry (60), the first axis of symmetry (60) and the second axis of symmetry (60) being coaxial, the distance between the outer wall (50) and the first body (70) in the middle region being constant, at least one first fluid feed (80) and an optional second fluid feed (90) being arranged in the middle region (30), the first fluid feed (80) and the optional second fluid feed (90) being designed to provide a uniform feed of fluid over the cross-section of the trickling device (10).

Description

[0001] Drying device for polymer granules

[0002] The invention relates to a device for drying polymer granules.

[0003] Corresponding devices are known from the prior art. In simplified form, the granulate is fed in from above, while gas is passed through in countercurrent from below.

[0004] A polyamide conditioning is known from EP 2 671 902 B1.

[0005] From DE 39 23 061 C1 a method and a device for drying and tempering polyamide granules are known.

[0006] WO 2009 / 153 340 A1 discloses a continuous process for multi-stage drying and post-condensation of polyamide granules.

[0007] US 2009 / 0163694 A1 discloses a process for the continuous drying of highly efficient aqueous aminoformaldehyde resin solutions.

[0008] However, it has been shown that in conventional systems, a particularly fast flow of granules occurs in the center of the device. This effect becomes more pronounced at larger radii, so the effect becomes stronger the larger the device. In contrast, the gas flow in this area is slow. This leads to different residence times of the granule particles and thus to different drying results.

[0009] The product homogeneity of granules, also called chips, is largely determined by the residence time distribution of the granules and the residence time distribution of the gas within the device. The gas can be fed countercurrently or cocurrently to the granules. Particularly with larger internal diameters of more than 2 m, conventional designs based on current design result in zones of slower flow and zones of faster flow. Capacities of more than 100 t / d for polyamide, for example, could therefore only be served with two devices operating in parallel. However, it is desirable to enable the realization of the drying stage, for example for polyamide with a throughput of 200 t / d and more, in one device.

[0010] The object of the invention is to create a flow profile for gas and granules which achieves particularly uniform drying.

[0011] This object is achieved by the trickling device having the features specified in claim 1. Advantageous further developments emerge from the subclaims, the following description, and the drawings.

[0012] The trickling device according to the invention is suitable for a particulate material. Such trickling devices are used as drying devices, condensation devices, post-condensation devices, conditioning devices, or as silo devices. The particulate material is particularly preferably a polymer granulate, in particular polyamide, polyethylene terephthalate, polylactide, and their copolymers. In particular, the trickling device serves to process these polymers after their production. The trickling device has a feed area, a central area, and an output area.

[0013] The particulate material is fed into the feed zone, then trickles through the central zone and lands at the bottom of the discharge zone, where it can be removed from the trickling device. Preferably, the outlet for the particulate material is located centrally at the bottom. Therefore, the feed zone is located above and immediately adjacent to the central zone, and the central zone is located above and immediately adjacent to the discharge zone.

[0014] The trickling device has an outer wall. The outer wall, within the meaning of the invention, is to be understood as the outer boundary of the interior space. The outer wall can have additional supporting structures, insulation layers, heat transfer surfaces, or the like on the outside, which, however, are not part of the outer wall within the meaning of the invention. The central region has a first axis of symmetry. For the example of a tubular outer wall, the central axis of the cylinder is the axis of symmetry. This runs vertically through the central region in the longitudinal direction. This would also be analogous for a polygonal cross-section, for example a square, hexagonal, or octagonal cross-section. A first body is arranged at least in the central region. The first body extends over the entire length of the central region, from top to bottom. The first body also has a second axis of symmetry.What has been said about the cross-section and the axis of symmetry of the outer wall applies here accordingly. The first axis of symmetry and the second axis of symmetry are identical, i.e. they lie exactly on top of one another. If, for example, both have a circular cross-section, the center point of both circular cross-sections is at the same position. The distance between the outer wall and the first body is constant in the central region. This means that the first body can, for example, taper; in this case, the taper also occurs in parallel in the outer wall, so that the constant distance does not negatively influence the residence time distribution. At least a first fluid inlet and an optional second fluid inlet are arranged in the central region or in the output region. An arrangement in the output region is preferably as directly below the central region as possible.The fluid inlets serve to supply a fluid, in particular a gas, into the interior. This can, on the one hand, fluidize the particulate material. Preferably, however, fluidization is not effected, but rather only drying. On the other hand, in the case of drying, a dry gas, for example nitrogen or dry air, is supplied to dry the particulate material. The first fluid inlet and the optional second fluid inlet are designed for the flat supply of fluid across the cross-section of the trickling device. A flat supply within the meaning of the invention is understood to mean a supply of fluid across the cross-section, in particular perpendicular or inclined to the axis of symmetry, with several supply points being present along the radial course.

[0015] Examples of planar supply of fluids include several ring-shaped elements with several supply points along the respective ring, whereby the different rings each have different radii. The elements for the planar distribution can also be non-ring-shaped; for example, they can be similar polygons of different sizes, such as hexagons with a common center point. Alternatively, the fluid feed can also be spiral-shaped. Furthermore, the planar supply can have an incline; in particular, the fluid feed is inclined so that it is higher on the outside than in the middle. Alternatively, the planar supply can be achieved by double-cone gassing, in which the fluid is supplied from the side due to the conical design of the casing, creating a slot-shaped supply.As a result, the fluid is supplied with a downward and inward velocity component, creating a flat distribution of the fluid. Furthermore, the conical shape can already be part of the constriction to a material withdrawal point arranged at the lower end. This embodiment is particularly preferred for a fluid inlet arranged at the lower end. The double-cone gassing is particularly preferably supplemented by an additional simultaneous fluid inlet at the lower end of the first body. The fluid inlet can be full-surface or structured, for example, through lateral nozzles. If two fluid inlets arranged one above the other are used, the upper one is preferably not designed as a double-cone gassing.

[0016] In particular, the fluid inlet does not have to be flat, i.e., arranged perpendicular to the axis of symmetry. In particular, the fluid inlet can be designed such that it is higher on the outside, which faces the outer wall, than on the side facing the first body. This is particularly preferred if the fluid inlets are firmly connected to the first body but not to the outer wall, as this optimizes the force flow.

[0017] The first fluid feed and the second fluid feed are arranged one above the other. Preferably, the first fluid feed is arranged in the upper 20% of the central region and the second fluid feed is arranged in the lower 20% of the central region.

[0018] The particulate material is in contact with the outer wall and the first body. This naturally also results in heat transfer between the particulate material and the outer wall or the first body. The particulate material typically has a particle size of 1 to 5 mm. For example, the average particle size can be 2.5 mm.

[0019] In a further embodiment of the invention, the outer wall has a constant first cross-section across the central region. Within the context of the invention, this means that the central region, for example and preferably, has a round cross-section with a radius r. The central region then has this round cross-section with radius r at every position along the longitudinal axis, thus resulting in the basic shape of a hollow cylinder. In this case, the outer wall in the central region would then be essentially a tube with a constant diameter r. In this embodiment, the first body has a constant second cross-section across the central region, analogous to the outer wall.

[0020] In a further embodiment of the invention, the diameter of the first body is at least as large as ten times the particle size of the particulate material, wherein the particle size used is the size at which 50% of all particles are below the particle size (dpso).

[0021] In a further embodiment of the invention, the diameter of the first body is 0.1 to 0.2 times the diameter of the outer wall.

[0022] In a further embodiment of the invention, the first body and the outer wall consist of the same material, in particular of stainless steel.

[0023] In a further alternative embodiment of the invention, the outer wall consists of a first material, for example, stainless steel, and the first body consists of a second material, for example, Plexiglas. Particularly preferably, the first material and the second material have a comparable roughness.

[0024] In a further embodiment of the invention, the ratio of the diameter of the outer wall to the diameter of the first body in the central region is in the range of 5:1 to 10:1. This ratio is particularly preferably 8:1. This achieves an optimum balance between homogenization and reduction of the volume used for the particulate material.

[0025] In a further embodiment of the invention, the length of the first body, in particular the length of the straight part of the first body, corresponds exactly to the length of the central region.

[0026] In a further embodiment of the invention, the first fluid inlet and the second fluid inlet are spaced apart from the outer wall, wherein the distance between the first fluid inlet and the outer wall, or between the second fluid inlet and the outer wall, corresponds to at least 10 times, preferably 20 times, the particle size of the particulate material, wherein the particle size used is the size at which 50% of all particles are below the particle size (dpso). Likewise, the first fluid inlet and the second fluid inlet are spaced apart from the first body, wherein the distance between the first fluid inlet and the first body, or between the second fluid inlet and the first body, corresponds to at least 10 times, preferably 20 times, the particle size of the particulate material, wherein the particle size used is the size at which 50% of all particles are below the particle size (dpso).If the first fluid feed and the second fluid feed consist of different elements, for example annular elements, these elements preferably also have a distance from one another which corresponds to at least 10 times, preferably 20 times, the particle size of the particulate material, wherein the particle size used is the size at which 50% of all particles are below the particle size (dpso).

[0027] In a further embodiment of the invention, the first fluid inlet and the second fluid inlet are spaced apart from the outer wall, wherein the distance between the first fluid inlet and the outer wall or the second fluid inlet and the outer wall corresponds to at most 120 times the particle size of the particulate material, wherein the particle size is used as the size at which 50% of all particles are below the particle size (dpso). Likewise, the first fluid inlet and the second fluid inlet are spaced apart from the first body, wherein the distance between the first fluid inlet and the first body or the second fluid inlet and the first body corresponds to at most 120 times the particle size of the particulate material, wherein the particle size is used as the size at which 50% of all particles are below the particle size (d Psee above). If the first fluid feed and the second fluid feed consist of different elements, for example annular elements, these elements are preferably also spaced apart from one another by a distance of at most 120 times the particle size of the particulate material, the particle size being the size at which 50% of all particles are below the particle size (d P so), corresponds.

[0028] In a further embodiment of the invention, the first fluid inlet and the second fluid inlet are spaced apart from the outer wall, wherein the distance between the first fluid inlet and the outer wall or between the second fluid inlet and the outer wall corresponds to 80 times the particle size of the particulate material, wherein the particle size is used as the size at which 50% of all particles are below the particle size (d P5o). Likewise, the first fluid feed and the second fluid feed are spaced apart from the first body, wherein the distance between the first fluid feed and the first body or the second fluid feed and the first body corresponds to 80 times the particle size of the particulate material, wherein the particle size is the size at which 50% of all particles are below the particle size (d P 5o). If the first fluid feed and the second fluid feed consist of different elements, for example annular elements, these elements preferably also have a distance from each other which is 80 times the particle size of the particulate material, wherein the particle size used is the size at which 50% of all particles are below the particle size (d P 5o), corresponds.

[0029] In a further embodiment of the invention, the trickling device has a third fluid feed, wherein the third fluid feed is preferably located in the center of the central region (center ± 10%). In a further embodiment of the invention, the first body has a conical shape in the feed area, with the tip pointing upward. This ensures good distribution of the particulate material, and no accumulation of particulate material forms on the first body.

[0030] In a further embodiment of the invention, the tip of the first body is spaced from the material feed in the feed area by a distance between the tip and the material feed corresponding to 50 to 300 times the particle size of the particulate material, with the particle size being the size at which 50% of all particles are below the particle size (dpso). Preferably, the distance between the tip and the material feed corresponds to 200 times the particle size of the particulate material.

[0031] In a further embodiment of the invention, the first fluid feed and the second fluid feed are rotationally symmetrical, in particular annular or polygonal, particularly preferably in the form of several concentric rings with different diameters.

[0032] In a further alternative embodiment, the fluid feed is spiral-shaped. Preferably, the spiral fluid feed has an incline, with the outer side preferably being higher than the inner side. Furthermore, with the spiral fluid feed, the distance between the various regions of the spirals corresponds to 50 to 10 times, particularly preferably 80 times, the particle size of the particulate material, with the particle size being the size at which 50% of all particles are below the particle size (dps0).

[0033] In a further embodiment of the invention, the trickling device has a fluid supply to the first fluid inlet and to the second fluid inlet, wherein the fluid supply is arranged in the first body. The fluid supplied from the outside reaches the fluid inlets and thus into the interior of the trickling device through the fluid supply. In a further embodiment of the invention, the first body is connected to the outer wall in a supporting manner in the feed area. Thus, the first body is arranged practically suspended in the interior. The advantage is that the flow of the particulate material is irregular in the feed area, but is no longer disturbed by supporting structures in the lower area.

[0034] In a further embodiment of the invention, the first body is connected to the outer wall in the discharge area. In particular, the first body is supported thereby. Particularly preferably, the first body is connected to the outer wall in the feed area in a load-bearing manner and to the outer wall in the discharge area. This achieves optimal attachment with minimal flow disruption in the central area.

[0035] In a further embodiment of the invention, the fluid supply is arranged partially in the connection between the first body and the outer wall in the feed area.

[0036] In a further embodiment of the invention, the trickling device is a drying device.

[0037] In a further embodiment of the invention, the first body can also have a more complex structure. For example, the first body can be constructed from three tubular partial bodies that are connected to each other and arranged symmetrically around the axis of symmetry.

[0038] During operation, the volume flow of the particulate material is preferably adjusted such that the ratio of the internal volume to the volume flow is between 2 and 25, preferably between 3 and 20, particularly preferably around 18. This means that an average residence time of 2 to 25, preferably 3 to 20, particularly preferably 18 hours is established for the particulate material.

[0039] The trickling device according to the invention is explained in more detail below using exemplary embodiments shown in the drawings. Fig. 1 first exemplary longitudinal section

[0040] Fig. 2 first exemplary cross-section

[0041] Fig. 3 second exemplary cross-section

[0042] Fig. 4 second exemplary longitudinal section

[0043] The exemplary embodiments are schematic and not to scale and serve only to illustrate the inventive ideas.

[0044] Fig. 1 shows a first exemplary longitudinal section of a trickling device 10. The trickling device 10 has a feed area 20 arranged at the top, a middle area 30 arranged below it, and an output area 40 arranged at the very bottom. A material feed 130, through which particulate material can be fed, opens into the feed area 20. The particulate material then trickles through the trickling device 10 and can then be removed again through a material removal 140 opening into the output area 40. The trickling device 10 has an axis of symmetry 60. The first body 70, which is connected to the outer wall 50 of the trickling device 10 via load-bearing connections 120 in the feed area 20 and is thus mechanically held, also lies on this axis of symmetry 60. A first fluid feed 80 and a second fluid feed 90 are arranged on the first body 70.In the feed area 20, the first body 70 has a conical tip 100, so that the particulate material introduced from the material feed 130 into the trickling device 10 is reliably guided into the central area 30. The conical tip 100 has an angle of 20° to 120°, preferably 40°, at the tip. Likewise, the output area 40 can have an angle of 10° to 60°, preferably 45°.

[0045] In order to introduce a fluid into the interior of the trickling device 10, the trickling device 10 has a fluid feed 110. The fluid is guided through the fluid feed 110 via a supporting connection 120 and the first body 70 into the two fluid inlets 80, 90 and from there into the interior of the trickling device 10 through fluid outlets, which are advantageously arranged on the underside of the two fluid inlets 80, 90. Fig. 2 and Fig. 3 show two different possible, exemplary cross-sections along AA in Fig. 1.

[0046] Fig. 2 shows a circular cross-section of the outer wall 50 and a circular cross-section of the first body 70. In the example shown, the first fluid inlet 80 consists of two annular components and four struts. These two annular components, and preferably also the struts, have fluid outlets on their undersides.

[0047] Fig. 3 shows a second alternative cross-section. The outer wall 50 and the first body 70 have a round cross-section, as in the first example shown. In contrast to the first example, the first fluid inlet 80 is hexagonal in shape, which simplifies the manufacture of the first fluid inlet 80.

[0048] The second exemplary longitudinal section shown in Fig. 4 differs from the first exemplary longitudinal section shown in Fig. 1 in that the two fluid inlets 80, 90 are inclined. This allows forces from the particulate material impacting from above to be better dissipated into the first body 70.

[0049] Reference symbol

[0050] 10 trickling device

[0051] 20 Task area

[0052] 30 middle range

[0053] 40 Output area

[0054] 50 exterior wall

[0055] 60 axis of symmetry

[0056] 70 first body

[0057] 80 first fluid feed

[0058] 90 second fluid feed

[0059] 100 conical tip

[0060] 1 10 Fluid supply

[0061] 120 supporting connection 130 material feed

[0062] 140 Material withdrawal

Claims

Patent claims 1. A trickling device (10) for a particulate material, wherein the trickling device (10) has a feed area (20), a central area (30) and a discharge area (40), wherein the feed area (20) is arranged above and immediately adjacent to the central area (30), wherein the central area (30) is arranged above and immediately adjacent to the discharge area (40), wherein the trickling device (10) has an outer wall (50), wherein the central area (30) has a first axis of symmetry (60), wherein at least in the central area (30) a first body (70) is arranged, wherein the first body (70) extends over the entire length of the central area (30), wherein the first body (70) has a second axis of symmetry (60), wherein the first axis of symmetry (60) and the second axis of symmetry (60) are identical, wherein the distance between the outer wall (50) and the first body (70) in the central area is constant is,wherein at least one first fluid feed (80) is arranged in the central area (30) or in the discharge area (40), wherein the first fluid feed (80) is designed for the planar supply of fluid over the cross-section of the trickling device (10).

2. Sprinkler device (10) according to claim 1 , characterized in that in the feed area (20) the first body (70) has a conical shape, with the tip pointing upwards.

3. Trickling device (10) according to one of the preceding claims, characterized in that a second fluid feed (90) is arranged in the central region (30), wherein the second fluid feed (90) is designed for the planar supply of fluid over the cross-section of the trickling device (10).

4. Sprinkler device (10) according to one of the preceding claims, characterized in that the first fluid feed (80) and the second Fluid inlet (90) are ring-shaped, spiral-shaped or hexagonal.

5. Sprinkler device (10) according to one of the preceding claims, characterized in that the sprinkler device (10) has a fluid supply (1 10) for has a first fluid feed (80) and a second fluid feed (90), wherein the fluid supply (1 10) is arranged in the first body (70).

6. Sprinkler device (10) according to one of the preceding claims, characterized in that the first body (70) is load-bearingly connected to the outer wall (50) in the feed area (20).

7. Sprinkler device (10) according to claim 5 and claim 6, characterized in that the fluid supply (1 10) is partially arranged in the connection between the first body (70) and the outer wall (50) in the feed area (20).

8. Sprinkler device (10) according to one of the preceding claims, characterized in that the sprinkler device (10) is a drying device.

9. Sprinkler device (10) according to one of the preceding claims, characterized in that the first body and the outer wall are made of the same material.

10. Sprinkler device (10) according to one of claims 1 to 8, characterized in that the outer wall is made of a first material and the first body is made of a second material. 1 1 . Sprinkler device (10) according to claim 10, characterized in that the first material and the second material have a comparable roughness.

12. Sprinkler device (10) according to one of the preceding claims, characterized in that the ratio of the diameter of the outer wall to the diameter of the first body in the central region is in the range of 5:1 to 10:

1.

13. Trickling device (10) according to one of the preceding claims, characterized in that the first fluid feed and the second fluid feed have a distance to the outer wall, wherein the distance between the first fluid feed and the outer wall or between the second fluid feed and the outer wall corresponds to at least 10 times the particle size of the particulate material. A trickling device (10) according to one of the preceding claims, characterized in that the first fluid inlet and the second fluid inlet are spaced apart from the first body, wherein the space between the first fluid inlet and the first body and the space between the second fluid inlet and the first body is at least 10 times the particle size of the particulate material. A trickling device (10) according to one of the preceding claims, characterized in that the first fluid inlet and the second fluid inlet are spaced apart from the outer wall, wherein the space between the first fluid inlet and the outer wall and the space between the second fluid inlet and the outer wall is at most 120 times the particle size of the particulate material.A trickling device (10) according to one of the preceding claims, characterized in that the first fluid inlet and the second fluid inlet are spaced apart from the first body, wherein the space between the first fluid inlet and the first body and the space between the second fluid inlet and the first body is at most 120 times the particle size of the particulate material. A trickling device (10) according to one of the preceding claims, characterized in that the first fluid inlet and the second fluid inlet are spaced apart from the outer wall, wherein the space between the first fluid inlet and the outer wall and the space between the second fluid inlet and the outer wall is 80 times the particle size of the particulate material.trickling device (10) according to one of the preceding claims, characterized in that the first fluid feed and the second fluid feed have a distance to the first body, wherein the distance between the first fluid feed and the first body and the second fluid feed and the first body corresponds to 80 times the particle size of the particulate material. A trickling device (10) according to one of the preceding claims, characterized in that in the feed area the tip of the first body has a distance to the material feed, wherein the distance between the tip and the material feed corresponds to 50 times to 300 times the particle size of the particulate material.

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