Apparatus for separating particles of different sizes by means of cyclonic separation

Abstract

The present invention relates to an apparatus for separating smaller particles from larger particles by means of cyclonic separation. The apparatus comprises a feeding pipe (2) having an upper end (2a) for receiving material to be separated and defining a first channel (3) for transporting the material to a lower end (2b) of the feeding pipe, a separation chamber (5) having a curved wall (7), a first opening (6a) arranged at an upper end (5a) of the separation chamber, a second opening (6b) arranged at a lower end (5b) of the separation chamber, and the separation chamber (5) surrounds the feeding pipe (2) such that a second channel (8) is formed between the feeding pipe and the curved wall (7), an air inlet unit (12) arranged for supplying air to the second opening (6b) of the separation chamber, and an outlet unit (15) arranged for receiving air and separated material from the first opening (6a) of the separation chamber and to discharge the air and separated material. The curved wall (7) is conically shaped and tapers from the second opening (6b) to the first opening (6a), and the feeding pipe and the separation chamber are concentrically arranged.

Claims

1. An apparatus (1) for separating smaller particles from larger particles by cyclonic separation, comprising: a feeding pipe (2) having an upper end (2a) for receiving material to be separated and defining a first channel (3) for transporting the material to a lower end (2b) of the feeding pipe, a separation chamber (5) having an outer curved wall (7), a first opening (6a) arranged at an upper end (5a) of the separation chamber (5), a second opening (6b) arranged at a lower end (5b) of the separation chamber (5), and surrounding the feeding pipe (2), a second channel (8) formed between the feeding pipe (2) and the outer curved wall (7), an air inlet unit (12) arranged for supplying air to the second opening (6b) of the separation chamber (5), and an outlet unit (15) arranged for receiving air and separated material from the first opening (6a) of the separation chamber (5) and discharging the air and separated material, wherein the feeding pipe (2) and the separation chamber (5) are concentrically arranged, and the second channel (8) is conically-shaped and continuously decreases toward the upper end (5a) of the separation chamber (5).

2. The apparatus according to claim 1, wherein said air inlet unit (12) comprises a housing (13) defining a curved third channel (46) for the air flow having an inlet opening (14) for receiving the air and the third channel is arranged in communication with a lower end (8b) of the second channel to allow the air flow in the curved third channel (46) to enter the lower end of the second channel (8), said outlet unit (15) comprises a housing (16) defining a curved fourth channel (48) for the air flow having an outlet opening (17) for discharging the air and separated material, the fourth channel is arranged in communication with an upper end (8a) of the second channel to allow the air flow in the second channel (8) to enter the fourth channel (48), and the apparatus comprises a suction unit (18) operatively connected to the outlet opening (17) of the outlet unit (15) and arranged for sucking air from said inlet opening (14) to said outlet opening (17) via said third, second and fourth channels so that a rotating air flow (22) is formed in said second channel (8) and smaller particles are transported upwards to the outlet unit (15) by the rotating air flow while larger particles are moved downwards due to gravity.

3. The apparatus according to claim 2, wherein said curved third channel (46) surrounds the separation chamber (5) and said curved fourth channel (48) surrounds the feeding pipe.

4. The apparatus according to claim 2, wherein said first opening (6a) is annular and surrounds the feeding pipe (2), and the fourth channel (48) is arranged in communication with the second channel (8) via said first opening (6a) of the separation chamber (5).

5. The apparatus according to claim 4, wherein the housing (16) of the outlet unit (15) is attached to the upper end (5a) of the separation chamber (5), and the housing (16) of outlet unit surrounds said first opening (6a) of the separation chamber.

6. The apparatus according to claim 2, wherein the air inlet unit (12) comprises a third opening (35) arranged in communication with the second opening (6b) of the separation chamber to allow the rotating air flow (22) in the curved third channel (46) to enter the second channel (8), and said third opening (35) is annular.

7. The apparatus according to claim 6, wherein the third opening (35) is formed between the separation chamber (5) and the housing (13) of the air inlet unit (12) and said third opening (35) surrounds the separation chamber (5).

8. The apparatus according to claim 2, wherein the suction unit (18) comprises a fan (19) with a variable speed.

9. The apparatus according to claim 1, wherein the apparatus comprises an impeller (25) rotatably arranged below the feeding pipe (2) and at a distance from the lower end (2b) of the feeding pipe, and the curved wall (7) of the separation chamber surrounds the impeller (25) such that a gap (27) is formed between the curved wall (7) and the outer periphery (26) of the impeller.

10. The apparatus according to claim 9, wherein said impeller (25) is arranged rotatable about an axis of symmetry (30) of the separation chamber (5), and the rotation of the impeller (25) is driven by said rotating air flow (22) caused by the suction unit.

11. The apparatus according to claim 10, wherein said second opening (6b) of the separation chamber is arranged below the impeller (25) for receiving air from the air inlet unit (12), and the air inlet unit (12) is arranged for supplying air to the second opening (6b) of the separation chamber.

12. The apparatus according to claim 9, wherein said second opening (6b) of the separation chamber is arranged below the impeller (25) for receiving air from the air inlet unit (12), and the air inlet unit (12) is arranged for supplying air to the second opening (6b) of the separation chamber.

13. The apparatus according to claim 9, wherein the apparatus comprises a collector unit (38) disposed below said gap (27) for collecting separated larger particles.

14. The apparatus according to claim 1, wherein the apparatus comprises an air lock (44) arranged to prevent air from entering the first channel together with the unseparated material.

15. The apparatus according to claim 1, wherein the apparatus comprises a filter unit (40) arranged between the outlet unit (15) and the suction unit (18).

16. The apparatus according to claim 1, wherein the second channel (8) is shaped such that radial width thereof (d1-d2) decreases toward the upper end (5a) of the separation chamber (5).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be explained more closely with reference to the appended figures.

(2) FIG. 1 shows a perspective view of an example of an apparatus for separating material according to the invention.

(3) FIG. 2 shows the apparatus shown in FIG. 1 seen from above.

(4) FIG. 3 shows a cross section A-A through the apparatus shown in FIG. 2 illustrating the air flow in the apparatus.

(5) FIG. 4 shows a cross-section B-B through the apparatus shown in FIG. 2 illustrating the air flow of material and separated particles in the apparatus.

(6) FIG. 5 shows a cross-section C-C through the apparatus shown in FIG. 3.

(7) FIG. 6 shows a cross-section D-D through the apparatus shown in FIG. 3.

(8) FIG. 7 shows another example of an apparatus for separating material according to the invention.

DETAILED DESCRIPTION

(9) FIG. 1 shows a perspective view of an example of an apparatus 1 according to the invention for separating smaller particles from larger particles in a material including particles of different sizes by means of cyclonic separation. FIG. 2 shows the apparatus shown in FIG. 1 seen from above. FIG. 3 shows a cross section A-A through the apparatus shown in FIG. 2, and FIG. 4 shows a cross section B-B through the apparatus. FIG. 5 shows a cross section C-C through the apparatus shown in FIG. 3, and FIG. 6 shows a cross section D-D through the apparatus shown in FIG. 3.

(10) The apparatus comprises a separation chamber 5 where separation of the material takes place and a feeding pipe 2 for feeding the material to the separation chamber 5, as shown in FIG. 4. The feeding pipe 2 is tubular and defines a first channel 3 for guiding transportation of the material to the separation chamber 5. The feeding pipe 2 has an inlet opening for receiving the material to be separated in an upper end 2a and an outlet opening for supplying the material to the separation chamber 5 at a lower end 2b of the feeding pipe. The radius of the separation chamber continually decreases from the lower end 2b to the upper end 2a. The feeding pipe 2 is vertically arranged.

(11) The separation chamber 5 has curved wall 7 surrounding the feeding pipe 2 such that a second channel 8 is formed between the feeding pipe and the wall. The second channel 8 has an upper end 8a and a lower end 8b, as shown in FIG. 3. The second channel 8 extends between the lower end 2b of the feeding pipe and the upper end 5a of the separation chamber 5. The curved wall 7 is conically shaped and tapers from the lower end 5b to the upper end 5a of the separation chamber. Accordingly, the separation chamber 5 and the second channel 2 are also conical and taper from the lower end 5b to the upper end 5a of the separation chamber. The feeding pipe and the separation chamber are concentrically arranged. The second channel 8 is annular and surrounds the feeding pipe 2, as shown in FIG. 2.

(12) The separation chamber 5 has a larger inner diameter d1 than the outer diameter d2 of the feeding pipe. The curved wall 7 enables the generation of a rotating flow of air and particles, i.e. a cyclone, inside the separation chamber 5. Preferably, the separation chamber 5 is rotationally symmetric with a circular cross section in order to generate a smooth flow. The feeding pipe 2 and the separation chamber 5 are concentrically arranged. The separation chamber 5 is conical having a wide end and a narrow end. The separation chamber 5 has a first opening 6a at an upper end 5a, and a second opening 6b at a lower end 5b. Since the curved wall 7 tapers from the second opening 6b to the first opening 6a, the first opening 6a is narrower than the second opening 6b. The radius of separation chamber 5 is continually decreasing towards the first opening 6a. The second channel 8 is conically shaped and tapers from the second opening 6b towards the first opening 6a of separation chamber 5. In this example, the first opening 6a is annular and surrounds the feeding pipe 2 and the second opening 6b is circular.

(13) The feeding pipe 2 penetrates through the first opening 6a of the separation chamber 5. The feeding pipe 2 protrudes into the separation chamber 5 and ends at a distance above the second opening 6b. The maximum size of the separated particles depends on the length of the second channel 8, and accordingly on the length of the part of the feeding pipe 2 protruding into the separation chamber, i.e. the distance between the upper end 5a of the separation chamber 5 and the lower end 2b of the feeding pipe. Thus, the apparatus can be roughly calibrated by selecting a certain length of the feeding pipe and adapting the length of the part protruding into the separation chamber in dependence on the desired maximum size of the particles to be separated from the material.

(14) The apparatus further comprises an air inlet unit 12 arranged for supplying air to the lower end 8b of the second channel, and an outlet unit 15 arranged at an upper end 8a of the second channel for discharging air and separated material. In this example, the outlet unit 15 comprises a curved housing 16 defining a curved fourth channel 48 surrounding the upper end 2a of the feeding pipe and arranged in communication with an upper end 8a of the second channel. The curved housing 16, and accordingly the fourth channel 48, has an outlet opening 17 for discharging air and separated material, as shown in FIG. 5. The curved housing 16 of the outlet unit 15 is at least partly ring-shaped and has a central though-hole for receiving the feeding pipe 2. In this example, the upper end 5a of the separation chamber 5 is attached to the outlet unit 15. The central through-hole of the curved housing 16 of the outlet unit 15 has an upper circular opening having a diameter corresponding to the outer diameter d2 of the feeding pipe and tightly connected to an upper part of the feeding pipe to provide an airtight seal between the outlet unit and the feeding pipe. The central through-hole of the curved housing 16 of the outlet unit has a lower circular opening having a diameter corresponding to the diameter of the upper end 5a of the separation chamber. The upper end 5a of the separation chamber 5 is attached to the outlet unit 15 so that the first opening 6a is arranged between the second channel 8 and the interior of the curved housing 16 to allow the rotating air flow 22 to enter the curved fourth channel 48 of the outlet unit 15, as shown in FIG. 3. Thus, the second channel 8 is in communication with fourth channel 48, i.e. the interior of the curved housing 16 of the outlet unit. In this example, the first opening 6a surrounds the feeding pipe 2, as shown in FIG. 5.

(15) In this example, the air inlet unit 12 comprises a curved housing 13 surrounding the separation chamber 5. The housing 13 defines a curved third channel 46 for the air flow and has an inlet opening 14 for receiving the air. The third channel 46 is arranged in communication with the lower end 8b of the second channel via a third opening 35 and the second opening 6b of the separation chamber, as shown in FIG. 3. In this example, the third opening 35 is annular and surrounds the separation chamber. The curved housing 13 of the inlet unit is attached to the separation chamber 5 so that the third opening 35 is formed between the interior of separation chamber 5 and the curved housing 13 of the air inlet unit to allow air from the inlet unit 12 to enter the second opening 6b of the separation chamber. In this example, the inlet unit 12 is attached to a lower part of the separation chamber 5. In this example, the curved housing 13 of the inlet unit 12 is at least partly ring-shaped and has a central though-hole for receiving the separation chamber 5. The central through-hole of the inlet unit 12 has an upper circular opening having a diameter corresponding to the outer diameter of a lower part of the separation chamber and is tightly connected to the separation chamber to provide an airtight seal between the inlet unit 12 and the separation chamber 5. The curved housing 13 of the inlet unit 12 has a circular opening having a diameter larger than the diameter of the lower part of the separation chamber 5 so that the annular third opening 35 is formed between the interior of the separation chamber 5 and the curved housing 13 of the inlet unit to allow air from the curved channel 46 of the inlet unit 12 to enter second opening 6b of the separation chamber 5. Thus, the second channel 8 is in communication with the interior of the curved housing 13 of the inlet unit.

(16) The apparatus further comprises a suction unit 18 connected to the outlet unit 15 for sucking air from the air inlet unit 12 to the outlet unit 15 so that a rotating air flow 22 is formed in the second channel 8 and smaller particles are transported upwards to the outlet unit 15 by means of the rotating air flow 22 while larger particles are moved downwards due to gravity. The suction unit is disposed outside the separation chamber 5 and the outlet unit 15. The outlet opening 17 of the outlet unit is operatively connected to the suction unit 18. Thus, the outlet unit can be directly or indirectly connected to the suction unit. In one embodiment, the suction unit 18 comprises a motor (not shown) and a fan 19 with a variable speed, as shown in FIG. 4. The suction unit 18 may be provided with a control device for controlling the speed of the fan. For example, the suction unit comprises a frequency converter adapted to control the speed of the fan 19. The maximum size of the separated material depends on the flow rate of the air flow 22 in the second channel 8, which depends on the speed of the fan. By having a fan with a variable speed, it is possible to control the maximum size of the separated material by varying the speed of the fan. Suitably, the control device is designed to allow a user to vary the speed of the fan so that the user easily can adjust the maximum size of the separated material. The maximum size of the separated material depends on the length of the second channel as well as the flow rate of the air flow in the second channel. Thus, the apparatus can firstly be roughly calibrated by adjusting the part of the feeding pipe protruding into the separation chamber, and then fine-tuned by adjusting the speed of the fan. Thus, it is possible to calibrate the apparatus to achieve a desired size of the separated material with high accuracy.

(17) The apparatus also comprises a lower part 37 surrounding the lower end 5b of the separation chamber 5 and is attached to the air inlet unit 12. In this example the lower part 37 is conical. In an alternative example, the lower part 37 can be cylindrical. In one aspect of the invention, the apparatus comprises collector unit 38 for collecting the separated larger particles. The collector unit 38 is attached to the lower part 37. The collector unit is optional.

(18) Suitably, a filter unit 40 is arranged between the suction unit 18 and the opening 17 of the outlet unit to prevent small particles from entering the suction unit 18 and by that reduce the risk of causing a fire if the small particles enter a motor of the suction unit, as shown in FIG. 4. Further, the apparatus may have an air lock 44 arranged to prevent air from entering the first channel 3 of the feeding pipe 2 together with the unseparated material, as shown in FIG. 7.

(19) In one aspect of the invention, the apparatus comprises an impeller 25 rotatable arranged below the feeding pipe 2 and at a distance from the lower end 2b of the feeding pipe, and the curved wall 7 of the separation chamber surrounds the impeller 25 such that a gap 27 is formed between the curved wall 7 and the outer periphery 26 of the impeller, as seen in FIGS. 3 and 6. Preferably, the impeller is centred in the separation chamber. The size of the gap 27 should be larger than the size of the largest particles to be separated. For example, the gap is larger than 20 mm.

(20) The second opening 6b of the separation chamber 5 is arranged below the impeller 25 for receiving air from the air inlet unit 12, and the air inlet unit 12 is arranged to supply air to the second opening 6b of the separation chamber. The impeller 25 is arranged rotatable about an axis of symmetry 30 of the separation chamber 5, and the rotation of the impeller 25 is driven by means of the rotating air flow 22 caused by the suction unit 18. The impeller comprises a centrum plate 28 and a plurality of blades 29 extending from the centrum plate 28 to the outer periphery 26 of the impeller. The upper surface of the impeller faces the outlet of the feeding pipe. The material from the feeding pipe hits the central plate 28 that pulverizes the material into particles. For example, the material consists of aggregated particles, such as lumps, of different sizes that need to be separated into separate particles before the smaller particles can be separated from the larger particles. The impeller causes loosening of aggregated material to enable separation of the aggregated material into separate particles. However, the impeller 25 is optional. If the material fed to the apparatus is not aggregated, the impeller is not needed.

(21) The function of the apparatus will now be explained with reference to the FIGS. 3, 4, and 5. The arrows shown in FIGS. 3 and 5 illustrate the air flow through the apparatus, and the arrows shown in FIG. 4 illustrate the flow of material and particles in the apparatus. When the suction unit 18 is started, a rotating air flow 22 is generated inside the separation chamber 5. The rotating air flow 22 forms a cyclone inside the separation chamber. The suction unit is tuned so that the flow rate of the rotating air flow 22 allows particles smaller than a set maximum size to be moved upwards in the second channel 8 and particles larger than the set maximum size to be moved downwards due to gravity acting on the particles.

(22) The suction unit 18 sucks air from the inlet unit 12 to the outlet unit 15 through the second channel 8, as seen in FIG. 3. The air flow enters the inlet unit 12 through the opening 14 and follows the curved housing 13 of the air inlet unit to cause the air flow to rotate, as shown in FIG. 5. The rotating air flow enters through the annular opening 35 between housing 13 of the air inlet unit 12 and the separation chamber 5, and then enters the separation chamber 5 through the lower end 5b of the separation chamber 5, as shown in FIG. 3. If the apparatus has an impeller 25, the rotating air flow hits the blades 29 of the impeller and causes the impeller to rotate. The rotating air flow penetrates through the impeller and the gap 27. The rotating air flow 22 enters the lower end 8b of the second channel 8 and rotates around the feeding pipe 2 towards the upper end 8a of the second channel, as shown in FIG. 3. The rotating air flow 22 enters the outlet unit 15 through the first opening 6a between second channel 8 and outlet unit 15 at the upper end 8a of the second channel 8. The rotating air flow 22 enters the curved housing 16 of the outlet unit and leaves the outlet unit through the opening 17 of the outlet unit, as shown in FIG. 5.

(23) Material to be separated is fed to the first channel 3 via the upper end 2a of the feeding pipe 2 and is supplied to the separation chamber 5 at the lower end 2b of the feeding pipe, as shown in FIG. 4. The material hits the central plate 28 of the rotating impeller 25. When the material has hit the impeller 25, the material is loosen and small particles of the material, i.e. particles having a size below the set maximum size, are moved upwards in the separation chamber 5 by means of the rotating air flow 22, and the larger particles, i.e. particles having a size above the set maximum size, are moved horizontally towards the gap 27 by centrifugal forces caused by the rotation of the impeller 25, and when the larger particles reach the gap 27 they will fall down below the impeller where they can be collected. The smaller particles will follow the rotating air flow 22 upwards towards the outlet unit 15 and leave the outlet unit 15 through the opening 17 of the outlet unit, as shown in FIG. 5.

(24) The present invention is not limited to the embodiments disclosed but may be varied and modified within the scope of the following claims. For example, the separation chamber, the air inlet unit and outlet unit can be designed in different ways. In an alternative example, the apparatus can be provided with a second air inlet unit disposed in a lower part of the apparatus below the first air inlet unit. In alternative embodiments of the invention, the second channel can be cylindrical or have the shape of an inverted cone.

REFERENCE LIST

(25) 1 Apparatus for separating particles 2 Feeding pipe 2a Upper end of feeding pipe 2b Lower end of feeding pipe 3 First channel 5 Separation chamber 5a Upper end of the separation chamber 5b Lower end of the separation chamber 6a First opening (outlet) of the separation chamber 6b Second opening (inlet) of the separation chamber 7 Curved wall of the separation chamber 8 Second channel 8a Upper end of the second channel 8b Lower end of the second channel 12 Air inlet unit 13 Curved housing of the air inlet unit 14 Inlet opening of the air inlet unit 15 Outlet unit 16 Curved housing of the outlet unit 17 Opening of the outlet unit 18 Suction unit 19 Fan of the suction unit 22 Rotating flow 25 Impeller 26 Outer periphery of the impeller 27 Gap 28 Centrum plate of the impeller 29 Blades of the impeller 30 Axis of symmetry of the separation chamber d1 Inner diameter of the separation chamber d2 Outer diameter of the feeding pipe 35 Third opening between second channel and inlet unit 37 Lower part 38 Collector unit 40 Filter unit 44 Air lock 46 Curved third channel of inlet unit 48 Curved fourth channel of outlet unit