TWI864572B - Drying device for polymer granules - Google Patents

Abstract

The present invention relates to a trickle device 10 for a particulate material, wherein the trickle device 10 has an input region 20, a centre region 30 and an output region 40, wherein the input region 20 is disposed above and directly adjacent to the centre region 30, wherein the centre region 30 is disposed above and directly adjacent to the output region 40, wherein the trickle device 10 has an outer wall 50, wherein the centre region 30 has a first axis of symmetry 60, wherein at least in the centre region 30 a first body 70 is disposed, wherein the first body 70 extends over the entire length of the centre region 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 coaxial, wherein the distance between the outer wall (50) and the first body (70) in the centre region is constant, wherein at least one first fluid feed 80 and an optional second fluid feed 90 are disposed in the centre region 30, wherein the first fluid feed 80 and the optional second fluid feed 90 are designed for the areal supply of fluid over the cross section of the trickle device 10.

Description

Drying device for polymer granules

Invention Field

The present invention relates to a device for drying polymer particles.

Invention Background

Corresponding devices are known in the prior art. In brief, particles are supplied from above and gas flows in countercurrent from below.

EP 2 671 902 B1 discloses polyamide conditioning.

DE 39 23 061 C1 discloses a method and a device for drying and thermal conditioning of polyamide granules.

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

US 2009/0163694 A1 discloses a continuous drying method for a high-efficiency amine formaldehyde resin aqueous solution.

However, it has emerged that in conventional plants a particularly fast central flow of particles occurs in the center of the device. This effect becomes more pronounced at larger radii and therefore becomes stronger with increasing size of the device. In contrast, the gas flow in this zone is slow. This leads to differences in the residence time of the granular particles and thus to differences in drying.

The product uniformity of the granules (also called fragments) is largely determined by the residence time distribution of the granules and the residence time distribution of the gas within the plant. The gas here can be conveyed countercurrently or cocurrently with the granules. In particular in the case of relatively large internal diameters of the plant, diameters of more than 2 m, the conventional configuration according to current designs is accompanied by a slower flow passage zone and a zone with a faster flow passage. Therefore, polyamide capacities of, for example, more than 100 t/d are only available using two plants operated in parallel. However, it would be desirable to be able to achieve a polyamide drying stage with a throughput of, for example, 200 t/d or more in one plant.

One object of the invention is to provide a flow profile for gases and particles which results in particularly uniform drying.

This object is achieved by a trickle device having the features specified in claim 1. Advantageous developments are evident from the dependent claims, the following description and the drawings.

According to one embodiment of the present invention, a dripping device (10) for particulate material is particularly provided, wherein the dripping device (10) has an input area (20), a central area (30) and an output area (40), wherein the input area (20) is arranged above the central area (30) and directly adjacent to the central area (30), wherein the central area (30) is arranged above the output area (40) and directly adjacent to the output area (40), wherein the dripping device (10) has an outer wall (50), wherein the central area (30) has a first symmetry axis (60), wherein at least in the central area (30) A first body (70) is provided in the central area (30), wherein the first body (70) extends over the entire length of the central area (30), wherein the first body (70) has a second symmetry axis (60), wherein the first symmetry axis (60) is identical to the second symmetry axis (60), wherein the distance between the outer wall (50) and the first body (70) in the central area is constant, wherein at least a first fluid feed (80) is provided in the central area (30) or in the output area (40), wherein the first fluid feed (80) is designed to supply fluid to a region on the cross section of the drip device (10).

Detailed description of preferred embodiments The dripping device of the present invention is suitable for particulate materials. These types of dripping devices are used as drying devices, condensing devices, post-condensation devices, conditioning devices or as storage devices. Particularly preferably, the particulate material is a particulate polymer, more particularly polyamide, polyethylene terephthalate, polylactide and copolymers thereof. In particular, after the production of these polymers, the dripping device is used for their processing. The dripping device has an input area, a central area and an output area.

In the input zone, particulate material is introduced, then trickles through the central zone and then falls to the bottom of the output zone where it can be removed from the trickling device. The outlet for the particulate material is preferably arranged in the center of the bottom. Therefore, the input zone is arranged above and directly adjacent to the central zone, and the central zone is arranged above and directly adjacent to the output zone.

The drip device has an outer wall. The outer wall in the sense of the present invention is understood to be the outer boundary of the interior. The outer wall may further have supporting structures, insulating layers, heat transfer areas or the like on the outside, however, in the terminology of the present invention, they are not part of the outer wall. The central area has a first symmetry axis. For the example of a tubular outer wall, the central axis of the cylinder is the symmetry axis. It extends vertically through the central area in the longitudinal direction. Similarly, the same is true for polygonal cross-sections, for example square, hexagonal or octagonal cross-sections. At least a first main body is provided in the central area. The first main body extends over the entire length of the central area from top to bottom. The first main body also has a second symmetry axis. Correspondingly, what has been said about the cross-section and the axes of symmetry of the outer wall is valid here. The first and second axes of symmetry are identical and therefore lie exactly on one another. For example, when they both have a circular cross-section, the center points of the two circular cross-sections are located at the same position. The distance between the outer wall and the first body is constant in the central region. This means that, for example, the first body may taper; in this case, the taper also occurs parallel in the outer wall, so that the constant distance means that there is no adverse effect on the residence time distribution. At least one first fluid feed and optionally one second fluid feed are provided in the central region or in the output region. The arrangement in the output zone preferably takes place as far as possible directly below the central zone. The fluid feeds serve to supply fluids, more specifically gases, into the interior. This firstly makes fluidization of the particulate material possible. However, preferably no fluidization is caused, but only drying. Secondly, in the case of drying, a dry gas, for example nitrogen, or dry air is supplied in order to dry the particulate material. The first fluid feed and the optional second fluid feed are designed for regional supply of fluids in a cross-section of the drip device. In the sense of the present invention, regional supply refers to the supply of fluids in a cross-section, in particular perpendicular to or inclined to the axis of symmetry, with multiple supply points along the radial section.

An example of a zone supply of a fluid is, for example, a plurality of annular elements with a plurality of supply points along individual rings, in which case the individual rings each have a different radius. In this context, the elements used for the zone distribution may also not be annular, and may, for example, be similar polygons of different sizes, for example hexagons with a common center point. Alternatively, the fluid feed may also have a spiral design. In addition, the zone supply may feature an inclination, more specifically, the fluid supply is inclined so that it is arranged higher on the outside than in the center. The zone supply can alternatively be realized by a double cone gas supply system, in which the fluid supply from the side creates a slit supply through the cone-shaped structure of the sleeve. As a result, the fluid is supplied with a velocity component directed downwardly and inwardly, resulting in a two-dimensional distribution of the fluid. Furthermore, the cone may be an already narrowed portion leading to a material discharge arranged at the bottom. This embodiment is particularly preferred for a fluid feed arranged at the bottom. Particularly preferably, the double cone gas supply system is supplemented by an additional, parallel fluid feed at the bottom end of the first body. In this case, the fluid feed can take place over the entire area or in a structured manner, for example by means of lateral nozzles. When two fluid feeds arranged one above the other are used, preferably the higher one is not implemented with a double cone gas supply system.

In particular, the fluid feed does not need to be horizontal, i.e. arranged perpendicularly to the axis of symmetry. In particular, the fluid feed can be embodied on the outer side facing the outer wall, which is higher than the side facing the first body. It is particularly preferred if the fluid feed is firmly joined to the first body and not to the outer wall, since this optimizes the force flow.

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.

The particulate material is in contact with the outer wall and also in contact with the first body. As a result, naturally, heat transfer also occurs between the particulate material and the outer wall and the first body, respectively.

The particulate material may typically have a particle size of 1 to 5 mm. For example the average particle size may be 2.5 mm.

In a further embodiment of the invention, the outer wall has a constant first cross-section in the central region. This means in the sense of the invention that the central region, for example and preferably, has a circular cross-section with a radius r. The central region then has this circular cross-section with a radius r at every position along the longitudinal axis, resulting in the basic shape of a hollow cylinder. In this case, the outer wall in the central region can be said to be a tube with a constant diameter r. In this embodiment, the first body has a constant second cross-section in the central region, similar to the outer wall.

In a further embodiment of the invention, the diameter of the first body is at least ten times greater than the particle size of the particulate material, the particle size being the size below which 50% of all particles are located (d _p50 ).

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

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

In a further alternative embodiment of the present invention, the outer wall is made of a first material (for example, stainless steel), and the first body is made of a second material (for example, plastic glass). Particularly preferably, the first material and the second material have a comparable roughness.

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. Particularly preferred this ratio is 8:1. In this way, an optimum is achieved between homogenization and reducing the volume for the particulate material.

In a further embodiment of the present invention, the length of the first body, more specifically the length of the straight portion of the first body, corresponds exactly to the length of the central area.

In a further embodiment of the invention, the first fluid feed and the second fluid feed are at a distance from the outer wall, wherein the distance between the first fluid feed and the outer wall and the distance between the second fluid feed and the outer wall respectively corresponds to at least 10 times, preferably 20 times, a particle size of the particulate material, the particle size being the size below which 50% of all particles are located ( _dp50 ). Similarly, the first fluid feed and the second fluid feed are at a distance from the first body, wherein the distance between the first fluid feed and the first body and the distance between the second fluid feed and the first body respectively corresponds to at least 10 times, preferably 20 times, a particle size of the particulate material, the particle size being the size below which 50% of all particles are located ( _dp50 ). Wherein the first fluid feed and the second fluid feed consist of different elements, for example annular elements, which preferably have a distance from each other corresponding to at least 10 times, preferably 20 times, a particle size of the particulate material, the particle size being the size below which 50% of all particles are located (d _p50 ).

In a further embodiment of the invention, the first fluid feed and the second fluid feed are at a distance from the outer wall, wherein the distance between the first fluid feed and the outer wall and the distance between the second fluid feed and the outer wall respectively corresponds to at most 120 times the particle size of the particulate material, the particle size being the size below which 50% of all particles are located ( _dp50 ). Similarly, the first fluid feed and the second fluid feed are at a distance from the first body, wherein the distance between the first fluid feed and the first body and the distance between the second fluid feed and the first body respectively corresponds to at most 120 times the particle size of the particulate material, the particle size being the size below which 50% of all particles are located ( _dp50 ). Wherein the first fluid feed and the second fluid feed consist of different elements, for example annular elements, which preferably have a distance from one another which also corresponds to at most 120 times the particle size of the particulate material, the particle size being the size below which 50% of all particles are located (d _p50 ).

In a further embodiment of the invention, the first fluid feed and the second fluid feed are at a distance from the outer wall, wherein the distance between the first fluid feed and the outer wall and the distance between the second fluid feed and the outer wall respectively correspond to 80 times the particle size of the particulate material, the particle size used being the size below which 50% of all particles are located (d _p50 ). Similarly, the first fluid feed and the second fluid feed are at a distance from the first body, wherein the distance between the first fluid feed and the first body and the distance between the second fluid feed and the first body respectively correspond to 80 times the particle size of the particulate material, the particle size used being the size below which 50% of all particles are located (d _p50 ). Wherein the first fluid feed and the second fluid feed consist of different elements, for example annular elements, the elements preferably have a distance from one another which also corresponds to 80 times the particle size of the particulate material, the particle size being the size below which 50% of all particles are located (d _p50 ).

In a further embodiment of the present invention, the dripping device has a third fluid feed, wherein the third fluid feed is preferably arranged at the center of the central area (center point ±10%).

In a further embodiment of the invention, in the input region, the first body has a cone shape with the tip pointing upwards. In this way, an efficient distribution of the particulate material is achieved without accumulation of particulate material on the first body.

In a further embodiment of the invention, in the input region, the tip of the first body has a distance from the material supply line, wherein the distance between the tip and the material supply line corresponds to 50 to 300 times the particle size of the particulate material, the particle size used being the size below which 50% of all particles are (d _p50 ). The distance between the tip and the material supply line preferably corresponds to 200 times the particle size of the particulate material.

In a further embodiment of the invention, the first fluid feed and the second fluid feed have a rotationally symmetrical design, in particular annular or polygonal, particularly preferably in the form of a plurality of concentric rings with different diameters.

In a further alternative embodiment, the fluid feed has a spiral design. The spiral fluid feed preferably has a slope, wherein preferably the outer side is higher than the inner side. Furthermore, in the case of a spiral fluid feed, the distance between different zones of the spiral corresponds to 50 to 100 times, more preferably 80 times, the particle size of the particulate material, the particle size used being the size below which 50% of all particles are below this particle size ( _dp50 ).

In a further embodiment of the invention, the drip device has a fluid supply line to the first fluid feed and to the second fluid feed, wherein the fluid supply line is arranged in the first body. Through the fluid supply line, the fluid supplied from the outside reaches the fluid feed and thus reaches the interior of the drip device.

In a further embodiment of the invention, the first body in the input region is supportedly connected to the outer wall. Therefore, the first body is actually suspended inside. The advantage is that the flow of the particulate material in the input region is irregular, but is no longer disturbed by the supporting structure in the bottom region.

In a further embodiment of the invention, the first body is joined to the outer wall in the output region. As a result, in particular, the first body is supported. Particularly preferably, the first body is joined to the outer wall in a supporting manner in the input region and in the output region. As a result, optimal safety and minimal flow disturbances are achieved in the central region.

In a further embodiment of the present invention, the fluid supply pipeline portion is arranged at the connection between the first body and the outer wall in the input area.

In a further embodiment of the present invention, the dripping device is a drying device.

In a further embodiment of the present invention, the first body may also have a more complex structure. For example, the first body may be composed of three tubular sub-elements, which are mutually engaged and symmetrically constructed around a symmetry axis.

In operation, the volume flow of the particulate material is preferably established so that the ratio of the internal volume to the volume flow is between 2 and 25, preferably between 3 and 20, more preferably around 18. This means that the average residence time for the particulate material is established to be 2 to 25 hours, preferably 3 to 20 hours, more preferably 18 hours.

The drip device of the present invention is described in more detail below in conjunction with the exemplary embodiments shown in the drawings. Figure 1: First exemplary longitudinal section Figure 2: First exemplary cross section Figure 3: Second exemplary cross section Figure 4: Second exemplary longitudinal section

The exemplary embodiments are schematic and not to scale and are merely intended to illustrate the concepts according to the invention.

FIG. 1 shows a first exemplary longitudinal section through a drip device 10. The drip device 10 has an input zone 20 arranged at the top, a central zone 30 arranged below it and an output zone 40 arranged at the very bottom. A material supply line 130 leads to the input zone 20 and allows the supply of particulate material. The particulate material then trickles through the drip device 10 and can then be removed again via a material discharge 140 opened at the output zone 40. The drip device 10 has a symmetry axis 60. Also situated on this symmetry axis 60 is a first body 70, which is joined to the outer wall 50 of the drip device 10 via a support connection 120 in the input zone 20 and is thus mechanically fixed. Arranged on the first body 70 are a first fluid feed 80 and a second fluid feed 90. In the input area 20, the first body 70 has a conical tip 100, so that the particulate material introduced into the drip device 10 from the material supply pipeline 130 is reliably guided into the central area 30. The conical tip 100 has an angle of 20° to 120° at the tip, preferably 40°. The output area 40 may also have an angle of 10° to 60°, preferably 45°.

In order to be able to introduce fluid into the interior of the dripping device 10, the dripping device has a fluid supply line 110. Through the fluid supply line 110, the fluid enters the two fluid feeds 80 and 90 via the support connector 120 and the first body 70, where it enters the interior of the dripping device 10 through the fluid outlet, which is advantageously arranged at the bottom of the two fluid feeds 80 and 90.

FIG. 2 and FIG. 3 show two different possible exemplary cross sections along A-A in FIG. 1 .

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 feed 80 is composed of two annular components and four pillars. The two annular components and preferably the pillars also have a fluid outlet at the bottom.

Fig. 3 shows a second alternative cross section. As shown in the first example, the outer wall 50 and the first body 70 have a circular cross section. In contrast to the first example, the first fluid feed 80 is implemented in a hexagonal form, thereby simplifying the production of the first fluid feed 80.

The second exemplary longitudinal section shown in Figure 4 differs from the first exemplary longitudinal section shown in Figure 1 in that the two fluid feeds 80 and 90 have an inclination. This makes it possible to more effectively transfer the force into the first body 70 through the particulate material arriving from the top.

Reference symbols 10: drip device 20: input area 30: central area 40: output area 50: outer wall 60: symmetry axis 70: first body 80: first fluid feed 90: second fluid feed 100: conical tip 110: fluid supply pipeline 120: support connector 130: material supply pipeline 140: material discharge

The drip device of the present invention is described in more detail below in conjunction with the exemplary embodiments shown in the drawings. Figure 1: First exemplary longitudinal section Figure 2: First exemplary cross section Figure 3: Second exemplary cross section Figure 4: Second exemplary longitudinal section

10: Drip device

20: Input area

30: Central area

40: Output area

50: Outer wall

60: Symmetrical axis

70: First Subject

80: First fluid feed

90: Second fluid feed

100: Conical tip

110: Fluid supply pipeline

120: Support connector

130: Material supply pipeline

140: Material discharge

Claims (17)

A dripping device (10) for particulate material, wherein the dripping device (10) has an input area (20), a central area (30) and an output area (40), wherein the input area (20) is arranged above the central area (30) and directly adjacent to the central area (30), wherein the central area (30) is arranged above the output area (40) and directly adjacent to the output area (40), wherein the dripping device (10) has an outer wall (50), wherein the central area (30) has a first symmetry axis (60), wherein a first body (70) is arranged at least in the central area (30), wherein the first body (70) extends over the entire length of the central area (30), wherein the first body (70) has a A second symmetry axis (60), wherein the first symmetry axis (60) and the second symmetry axis (60) are the same, wherein the distance between the outer wall (50) and the first body (70) in the central area is constant, wherein at least one first fluid feed (80) is provided in the output area (40), wherein the first fluid feed (80) is designed to be used for regional supply of fluid on the cross section of the drip device (10), wherein the first body (70) in the input area (20) is supportedly connected to the outer wall (50), wherein a second fluid feed (90) is provided in the central area (30), wherein the second fluid feed (90) is designed to be used for regional supply of fluid on the cross section of the drip device (10). The drip device (10) of claim 1 is characterized in that the first body (70) has a cone shape in the input area (20) with the tip pointing upward. The dripping device (10) of claim 1 is characterized in that the first fluid feed (80) and the second fluid feed (90) have a ring-shaped, spiral or hexagonal design. The drip device (10) of claim 1 is characterized in that the drip device (10) has a fluid supply pipeline (110) to the first fluid feed (80) and to the second fluid feed (90), wherein the fluid supply pipeline (110) is arranged in the first body (70). The drip device (10) of claim 4 is characterized in that the fluid supply pipeline (110) is partially arranged at the connection between the first main body (70) and the outer wall (50) in the input area (20). The dripping device (10) of claim 1 is characterized in that the dripping device (10) is a drying device. The drip device (10) of claim 1 is characterized in that the first body and the outer wall are made of the same material. The drip device (10) of claim 1 is characterized in that the outer wall is composed of a first material and the first body is composed of a second material. The drip device (10) of claim 8 is characterized in that the first material and the second material have comparable roughness. The drip device (10) of claim 1 is characterized in that the ratio of the diameter of the outer wall in the central area to the diameter of the first body is in the range of 5:1 to 10:1. The dripping device (10) of claim 1 is characterized in that the first fluid feed and the second fluid feed are spaced apart from the outer wall, wherein the distance between the first fluid feed and the outer wall and the distance between the second fluid feed and the outer wall respectively correspond to at least 10 times the diameter of the particle material. The dripping device (10) of claim 1 is characterized in that 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 and the distance between the second fluid feed and the first body correspond to at least 10 times the particle size of the particulate material, respectively. The dripping device (10) of claim 1 is characterized in that the first fluid feed and the second fluid feed are spaced apart from the outer wall, wherein the distance between the first fluid feed and the outer wall and the distance between the second fluid feed and the outer wall respectively correspond to at most 120 times the particle size of the particulate material. The dripping device (10) of claim 1 is characterized in that 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 and the distance between the second fluid feed and the first body correspond to at most 120 times the particle size of the particulate material, respectively. The dripping device (10) of claim 1 is characterized in that the first fluid feed and the second fluid feed are spaced apart from the outer wall, wherein the distance between the first fluid feed and the outer wall and the distance between the second fluid feed and the outer wall correspond to 80 times the particle size of the particulate material, respectively. The dripping device (10) of claim 1 is characterized in that 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 and the distance between the second fluid feed and the first body correspond to 80 times the particle size of the particulate material, respectively. The drip device (10) of claim 1 is characterized in that, in the input area, the tip of the first body is at a distance from a material supply pipeline, wherein the distance between the tip and the material supply pipeline corresponds to 50 to 300 times the particle size of the particulate material.