Device for cooling particulate materials

Abstract

Disclosed is a device for cooling particulate materials or particles, in particular granulates of polymeric materials, having an outer container with an, in particular frustoconical, outer shell surface and an inner container, which is arranged at least in sections in the interior of the outer container, with an, in particular frustoconical, inner shell surface, wherein an intermediate space is formed between the outer shell surface and the inner shell surface, wherein an inlet equipment for introducing a gas flow as well as the particles into the intermediate space is provided in an inlet-side initial region of the device, and wherein an outlet opening for the particles is provided in an outlet-side end region of the device opposite the inlet equipment, wherein the inlet equipment is so arranged and/or designed that the gas flow as well as the particles can be introduced substantially tangentially into the intermediate space.

Claims

1. A device for cooling particulate materials or particles, comprising: an outer container with an outer shell surface; and an inner container, which is arranged at least in sections in an interior of the outer container, with an inner shell surface, wherein an intermediate space is formed between the outer shell surface and the inner shell surface, wherein an inlet equipment for introducing a gas flow and the particles into the intermediate space is provided in an inlet-side initial region of the device, and wherein an outlet opening for the particles is provided in an outlet-side end region of the device opposite the inlet equipment, wherein the inlet equipment is arranged and/or designed in such a way that the gas flow and the particles can be introduced substantially tangentially into the intermediate space, the inlet equipment has an inlet channel and, an inlet nozzle which is arranged upstream thereof and via which the gas and particle flow can be fed, wherein the inlet channel is of curved design and runs parallel to a circumference of the outer shell surface and of the inner shell surface, and opens into the intermediate space essentially tangentially and in that the inlet channel closes the intermediate space on the inlet side.

2. The device according to claim 1, wherein the outer shell surface and/or the inner shell surface are arranged substantially rotationally symmetrically about a central longitudinal axis.

3. The device according to claim 1, wherein the outer shell surface and/or the inner shell surface is inclined relative to a central longitudinal axis by a cone angle (β), wherein the cone angle (β) is in a range of 1°<=β<=15°.

4. The device according to claim 1, wherein the outer shell surface and the inner shell surface are spaced apart from one another on all sides without contact.

5. The device according to claim 1, wherein the outer shell surface and the inner shell surface are aligned parallel to one another.

6. The device according to claim 1, wherein a width (a) of the intermediate space between the outer shell surface and the inner shell surface is in a range 20 mm<=a<=200 mm.

7. The device according to claim 1, wherein a width (a) of the intermediate space between the outer shell surface and the inner shell surface decreases uniformly in a direction of the outlet-side end region.

8. The device according to claim 1, wherein a width (a) of the intermediate space between the outer shell surface and the inner shell surface increases uniformly in a direction of the outlet-side end region.

9. The device according to claim 1, wherein a length or height (ha) of the outer container or of the outer shell surface is greater than the length or height (hi) of the inner container or of the inner shell surface, wherein a ratio (hi):(ha) is in a range from 0.1 to less than 1.

10. The device according to claim 1, wherein the outer shell surface and the inner shell surface are flush at their inlet-side initial regions.

11. The device according to claim 1, wherein the outer shell surface extends further or is longer than the inner shell surface in a direction of the outlet-side end region.

12. The device according to claim 1, wherein the diameter (da1) of the outer shell surface at the inlet-side initial region is greater than its diameter (da2) at the outlet-side end region, or in that the outer container tapers in a direction of the outlet-side end region.

13. The device according to claim 1, wherein in that a diameter (di1) of the inner shell surface at the inlet-side initial region is greater than its outlet-side diameter (di2) at the outlet-side end region, or wherein the inner container tapers in a direction of the outlet-side end region.

14. The device according to claim 1, wherein the outer shell surface and the inner shell surface taper in a direction of the outlet-side end region.

15. The device according to claim 1, wherein the opening of the outer shell surface defined by a diameter (da2) at the outlet-side end region or an area defined by the diameter of the outlet opening is reduced relative to the opening of the inner shell surface defined by the diameter (di2) at the outlet-side end region in such a way that sufficient flow resistance is formed for the gas to effect separation of the particles from the gas.

16. The device according to claim 1, wherein a tapering outlet nozzle is arranged at the outlet-side end region of the outer shell surface, in which the outlet opening is provided, via which the particle flow exits the device, wherein an area of the outlet opening is <=20% of an area of the opening, defined by a diameter (da2) at the outlet-side end region, of the outer shell surface.

17. The device according to claim 1, wherein the inner shell surface is open or gas-permeable at its end close to the inlet-side initial region, or is optionally provided with a gas-permeable cover surface.

18. The device according to claim 1, wherein the inlet channel has the same width (a) as the intermediate space.

19. The device according to claim 1, wherein the inlet channel opens into the intermediate space at an angle (α) with respect to a plane aligned normal to a longitudinal axis, wherein the angle (α) is in a range of 0<α<=10°, wherein it is provided that the inlet channel is uniformly inclined at the angle (α) over its entire longitudinal extent.

20. The device according to claim 1, wherein additional gas inlet openings are formed in the outer shell surface and/or in the inner shell surface, which openings are arranged and/or designed in such a way that gas can be introduced, essentially tangentially, into the intermediate space via these gas inlet openings.

21. The device according to claim 3, wherein the outer shell surface and/or the inner shell surface is inclined relative to a central longitudinal axis by a cone angle (β), wherein the cone angle (β) is in a range of 3°<=β<=10°.

22. The device according to claim 3, wherein the outer shell surface and/or the inner shell surface is inclined relative to a central longitudinal axis by a cone angle (β), wherein the cone angle (β) is in a range of 3°<=β<=6°.

23. The device according to claim 6, wherein the width (a) of the intermediate space between the outer shell surface and the inner shell surface is in a range 50 mm<=a<=100 mm.

24. The device according to claim 6, wherein the width (a) of the intermediate space between the outer shell surface and the inner shell surface is in a range 60 mm<=a<=80 mm.

25. The device according to claim 9, wherein the ratio (hi):(ha) is in a range from 0.3 to 0.85.

26. The device according to claim 9, wherein the ratio (hi):(ha) is in a range from 0.50 to 0.75.

27. The device according to claim 16, wherein the area of the outlet opening is <=10% of the area of the opening, defined by the diameter (da2) at the outlet-side end region of the outer shell surface.

28. The device according to claim 1, wherein the outer shell surface and the inner shell surface are frustoconical.

Description

(1) The following show schematically:

(2) FIG. 1 a device according to the invention in perspective view,

(3) FIG. 2 a side view of the device according to FIG. 1,

(4) FIG. 3 or 3a a section B-B through this device,

(5) FIG. 4 a top view from above,

(6) FIG. 5 a test with a known comparison equipment

(7) FIGS. 6a, 6b tests with two cooling equipments according to the invention.

(8) FIGS. 1 to 4 show the device 1 according to the invention from different perspectives. In the present embodiment, the device 1 is positioned vertically, namely in a support frame. An inlet equipment 7 is arranged in the uppermost region of the device 1 for introducing the gas or particle flow. This upper section of the device 1 is defined as the inlet-side initial region 11. The section of the device 1 opposite the inlet equipment 7 is defined as the outlet-side end region 12. This is also where the outlet opening 15 is located, from which the particles leave the device 1.

(9) The device 1 comprises an outer container 2 and an inner container 4 arranged therein. The outer container 2 has a frustoconical outer shell surface 3, the inner container 4 has a frustoconical inner shell surface 5. The inner container 4 is arranged in the outer container 2 in such a way that an intermediate space 6 is formed between the outer shell surface 3 and the inner shell surface 5. The width a of the intermediate space between the outer shell surface 3 and the inner shell surface 5 is about 70 mm in the present case.

(10) The outer shell surface 3 and the inner shell surface 5 are continuously spaced from each other and do not touch at any point. Accordingly, the intermediate space 6 is barrier-free and a frustoconical annular space is formed in which the gas flow and the particles circulate in a spiral.

(11) The outer shell surface 3 and the inner shell surface 5 are inclined relative to a central longitudinal axis 10 by the cone angle β. In the present example of an embodiment, the cone angle β is about 5°.

(12) In the present example of an embodiment, the outer shell surface 3 and the inner shell surface 5 are aligned parallel to each other. However, it may be advantageous to deviate from a parallel alignment and, for example, to provide for an increase or a decrease in the gap width.

(13) It can be seen that the outer shell surface 3 and the inner shell surface 5 taper in the direction of the outlet-side end region 12, i.e. here towards the bottom. Accordingly, the diameter da1 of the outer shell surface 3 at the inlet-side end region 11 is larger than the diameter da2 of the outer shell surface 3 at the outlet-side end region 12 or, in this case, the lower opening 18 of the outer shell surface 3.

(14) Similarly, the diameter di1 of the inner shell surface 5 at the inlet-side initial region 11 or, in this case, the upper opening 19 of the inner shell surface 5 is larger than the outlet-side diameter di2 of the inner shell surface 5 at the outlet-side end region 12. The upper, relatively larger opening 19 of the inner shell surface 5 located at the inlet-side initial region 11 is thereby closed by a cover surface 17.

(15) It can also be seen that the outer shell surface 3 has a greater length or height ha than the height hi of the inner shell surface 5. In the device 1 according to FIG. 1 the ratio hi:ha is about 0.6.

(16) This means that in the lower section of the device 1 there is a separation region 16 in which the inner container 4 is already at the end and there is also no longer a defined intermediate space 6. This separation region 16 is only limited by the outer container 2 or the outer shell surface 3.

(17) However, the particles continue to move downwards along the outer shell surface 3 in the separation region 16. The gas flow, on the other hand, is discharged upwards at the end of the intermediate space 6 via the inner shell surface 5. This is where the particles are separated from the gas flow. The particles leave the device 1 at the bottom through the outlet opening 15, the gas leaves the device 1 at the top through the upper opening 19 of the inner shell surface 5. This upper opening 19 is provided with a gas-permeable cover surface 17, in the present case by a grid.

(18) Reducing the diameter of the outer shell surface 3 already increases the flow resistance. If the opening 18 at the lower end of the outer shell surface 3 is small enough, the flow resistance becomes so great that the gas does not exit through this lower opening 18, but rather only via the upper opening 19 of the inner shell surface 5. However, the particles always exit at the bottom and this lower opening 18 can, when it is small enough, also act as an outlet opening 15 at the same time. In most cases, however, this results in a greater overall height of the device 1. Accordingly, the flow resistance can also be further increased by additional design measures. Thus, as can be seen in the example of an embodiment according to FIG. 3a, an additional frustoconical outlet nozzle 13 is arranged at the very bottom of the outlet-side end region 12 of the outer shell surface 3. The actual outlet opening 15 for the particles, from which the particles finally leave the device 1, is also formed in this outlet nozzle 13. The outlet nozzle 13 is directly connected to the lower opening 18 of the outer shell surface 3, wherein the cross-sectional area of the outlet opening 15 is considerably smaller than that of the lower opening 18, in this case only approx. 7-8% of the cross-sectional area of the lower opening 18. Due to this additional cross-sectional constriction, the flow resistance is further increased and the separation of the particles from the gas flow is even more effective.

(19) The inlet equipment 7 arranged in the inlet-side initial region 11 has an inlet nozzle 8 to which, for example, a transport line can be connected, via which the still hot particles or granulates are introduced into the device 1 together with the gas flow.

(20) The inlet nozzle 8 opens into an inlet channel 9. This inlet channel 9 is curved or spirally curved and runs essentially circularly parallel to the circumference of the outer shell surface 3 and the inner shell surface 5. The inlet channel 9 closes the intermediate space 6 at the top or inlet-side. In the present case, with the present diameter of the shell surfaces 3, 5 and with the present angle of inclination a, the inlet channel 9 describes an almost complete circle of almost 360° and then opens into the intermediate space 6, approximately in the region below the inlet nozzle 8. Accordingly, the inlet channel 9 has the same width a as the intermediate space 6. Accordingly, the gas or particle flow is introduced tangentially into the intermediate space 6, i.e. the particles and the gas flow run on approximately circular paths around the central longitudinal axis 10 in the intermediate space 6. In addition, turbulent flows, tear-off edges and impact edges are thus avoided.

(21) At the same time, the inlet channel 9 is also slightly inclined downwards, towards the outlet. This can already be seen from FIG. 1, and the inlet channel 9 runs into the interior of the intermediate space 6 over a surface that is constantly inclined downwards. This inclined angle of entry α is defined with respect to a plane 14 that is aligned normal to the longitudinal axis 10 and is about 5°, as can be seen in FIG. 2.

(22) In this way, the particles or gas flow into the intermediate space 6 not only tangentially, but also directed slightly downwards. This results in a movement pattern such as can be seen in FIG. 6. The particles thus move along spiral paths from the inlet-side initial region 11 to the outlet-side end region 12, wherein the diameter of these spiral paths becomes smaller and smaller.

(23) The following embodiments show tests and results with different cooling equipments in comparison (FIG. 5 and FIG. 6a, 6b):

(24) The tests were performed with the following parameters: Air volume: 2700 m.sup.3/h Granulate quantity: 85 kg/h Medium: air Air temperature inlet: 19° C. Granulates were always singled out.

(25) TABLE-US-00001 Material + T granulate start T granulate end MatNo. Cyclone [° C.] [° C.] LDPE 20190227/4 “Standard” 137 101 20190227/5 “Type 2 137 75 (conical)” LDPE/PP 2019044/10 “Standard” 175 100 2019044/9 “Type 2 174 80 (conical)” LDPE/PP/CaCO3 2018220/31 “Standard” 171 109 2018220/20 “Type 2 173 75 (conical)”

(26) “Type Standard” (FIG. 5):

(27) Inlet Air: 0.6 kg/s; 20° C.

(28) Inlet Particle: 100 kg/h

(29) D 4 mm; 80 tracks

(30) “Type 1 (cylindrical)” (FIG. 6a, 6b, left column):

(31) Inlet air: 0.6 kg/s; 20° C.

(32) Inlet Particle: 100 kg/h

(33) D 4 mm; 50 tracks

(34) “Type 2 (conical)” (FIG. 6a, 6b, right column):

(35) Inlet air: 0.6 kg/s; 20° C.

(36) Inlet Particle: 100 kg/h

(37) D 4 mm; 50 tracks

(38) The tests were performed with different materials and, among other things, the velocity distribution and the residence time spectrum were investigated. The final temperature of the granulate was also used for evaluation.

(39) The cyclone known from the prior art as the “Type Standard” (FIG. 5) is a cylindrical cyclone and a conical end with a tangential air inlet, however without an inner container and without other equipments in the inner area. At the upper end there is an air outlet tube which protrudes approx. ⅓ into the cylinder. Among other things, the particle residence time was simulated for this cyclone. It is clearly visible in FIG. 5 that the particles penetrate very quickly into the lower area of the cyclone, i.e. they do not have a long residence time in the cooling silo, and an accumulation of particles occurs in the lower area or in the area of the outlet funnel. This leads to an increased particle frequency, where sticking can occur and twins and triplets (i.e. two or three granulates sticking to each other) are formed. In addition, this area also heats up and disruptive wall adhesions can occur as a result.

(40) In the cylindrical cooling silo with inner shell “Type 1 (cylindrical)” according to the invention (FIGS. 6a, 6b, left column), it is clearly visible, especially in the particle track (FIG. 6b), that the particles are guided more uniformly than in the cyclone “Type Standard”. The air guidance in the inlet region has an increased air velocity, which, however, decreases strongly over the height. However, this is not too much of a problem with small unfilled granulates with a lower specific weight, as the air can continue to hold the granulates at the circumference for a sufficiently long time.

(41) In the conical cooling silo with inner shell “Type 2 (conical)” according to the invention (FIG. 6a, 6b, right column), it is possible to keep the air flow largely constant over the height. Although the diameter of the silo decreases, this leads to a longer residence time of the granulates in the cooling silo. Furthermore, the air flow is sufficiently high that even specifically heavier granulates can be kept in the spiral and thus remain sufficiently separated and can be solidified/cooled accordingly.