WO2022051959A1

WO2022051959A1 - Vortex finder and cyclonic separator

Info

Publication number: WO2022051959A1
Application number: PCT/CN2020/114353
Authority: WO
Inventors: Yang Liu; Houliao ZHAO; Lichao KONG; Fei Wang; Meng Zhao
Original assignee: Robert Bosch Gmbh
Priority date: 2020-09-10
Filing date: 2020-09-10
Publication date: 2022-03-17
Also published as: CN116171201A

Abstract

A vortex finder (100) is disclosed which comprises: a hollow cylinder (1) defining a vertically extending central axis (O) and formed with a vertical passage (2) therethrough; a top flange (3) extending transversely outwards from a top end of the cylinder (1); a bottom baffle (4) extending transversely outwards from a bottom end of the cylinder (1); a tubular wall (5) surrounding a lower part of the cylinder (1); and a plurality of blades (6) extending radially and connected between the cylinder (1) and the tubular wall (5). A cyclonic separator comprising a vortex finder described above is also disclosed. The vortex finder has a high separation efficiency and a low pressure drop.

Description

Vortex Finder and Cyclonic Separator

Technical Field

The disclosure relates to a vortex finder for a cyclonic separator and a cyclonic separator comprising such a vortex finder.

Background Art

Cyclonic separators are generally used in industrial and household appliances for separating solid particulates and liquid droplets from a gas by rotational effects without using a filter.

Known cyclonic separators comprise a cyclone chamber with an inlet arranged offset from the central axis of the cyclone chamber to generate a rotational flow or vortex of gas within the cyclone chamber. Particulates and droplets entrained in the gas move towards the wall of the cyclone chamber under the centrifugal force generated by the vortex and then fall into a collection chamber. A vortex finder is a common component in the cyclonic separators to improve separation performance. Various vortex finders have been designed for different applications, but there is still room for increasing separation efficiency and reducing pressure drop related with the vortex finders.

Summary of the Disclosure

The disclosure is aimed at providing a vortex finder for a cyclonic separator which has an improved synthesized performance.

In one aspect, the disclosure provides a vortex finder for a cyclonic separator comprising:

a hollow cylinder defining a vertically extending central axis and formed with a vertical passage therethrough;

a top flange extending transversely outwards from a top end of the cylinder;

a bottom baffle extending transversely outwards from a bottom end of the cylinder;

a tubular wall surrounding a lower part of the cylinder; and

a plurality of blades extending radially and connected between the cylinder and the tubular wall, a circular space being formed around an upper portion of the cylinder between the plurality of blades and the top flange.

In one embodiment, the bottom baffle has an outer diameter smaller than the inner diameter of the tubular wall so that a circular bottom gap is formed between the bottom edge of the tubular wall and the outer periphery of the bottom baffle.

In one embodiment, a bottom surface of the bottom baffle is substantially flush with a bottom edge of the tubular wall in the axial direction.

In one embodiment, the outer periphery of the tubular wall has a diameter smaller than that of the outer periphery of the top flange.

In one embodiment, an upper surface of the bottom baffle is downwardly oblique from its inner periphery to its outer periphery with an oblique angle which is in the range of 5° to 20°.

In one embodiment, each blade has a blade root connected to the cylinder, a blade tip connected to the tubular wall, a blade top facing substantially upwards, and a blade bottom facing substantially downwards, and the blade bottom lies ahead of the blade top in the direction opposite to an incoming rotational direction of a flow to be formed in the vortex finder.

In one embodiment, the blade bottom of each blade is substantially horizontal, and all the blade bottoms are substantially coplanar.

In one embodiment, the blade top of each blade is substantially horizontal; or the blade top of each blade is downwardly oblique from the corresponding blade root to the blade tip by an angle which is in the range of 5° to 30°.

In one embodiment, the blade bottom is offset by an offset angle with respect to the blade top in the direction opposite to the incoming rotational direction when looking in the axial direction, the offset angle being in the range of 5° to 30°.

In one embodiment, at least one of the center line of the blade top and the center line of the blade bottom is a straight line when looking in the axial direction.

In one embodiment, the center line of the blade top and the center line of the blade bottom are both straight lines when looking in the axial direction.

In one embodiment, the extensions of both the center lines intersect the central axis; or the extension of one of the center line intersects the central axis while the extension of the other center line does not intersect the central axis; or neither one of the extensions of the center lines intersects the central axis.

In one embodiment, at least one of the center line of the blade top and the center line of the blade bottom is a curved line when looking in the axial direction.

In one embodiment, each blade is a planar blade; or each blade is a curved blade.

In one embodiment, the number of the blades is 8 to 16, and the blades are evenly arranged around the cylinder.

In one embodiment, some portions or all of the outer surface of the vortex finder is covered with a hydrophobic material.

In another aspect, the disclosure provides a cyclonic separator comprising:

a casing comprising a substantially vertical tube with a lower closed end and an upper open end;

a vortex finder, as described above, arranged in the tube, with the top flange of the vortex finder fixedly sealed against the inner surface of the tube;

an inlet transversely mounted to the tube, the inlet facing towards the circular space and directed in a direction offset from the central axis of the vortex finder; and

an outlet in fluid communication with an upper end of the passage.

A particular embodiment of the cyclonic separator is a water (or liquid) separator which can separate water (or liquid) entrained in a gas (for example, air) flow.

According to the disclosure, a vortex finder for providing both centrifugal separation and baffle separation is disclosed. The vortex finder has an improved synthesized performance since it is compact, has higher separation efficiency and causes lower pressure drop.

Brief Description of the Drawings

Figure 1 is a perspective view of a vortex finder according to an embodiment of the disclosure;

Figure 2 is a schematic front view of the vortex finder;

Figures 3 and 4 are respectively a schematic cross sectional view and a partial top view of a cyclonic separator comprising the vortex finder according to an embodiment of the disclosure;

Figure 5 is an enlarged partial view of a bottom baffle of the vortex finder;

Figure 6 is a schematic front view of the vortex finder showing the distribution of blades;

Figures 7 and 8 are schematic views of the vortex finder showing the configuration of a blade in different directions; and

Figures 9 to 12 are schematic top views showing some possible configurations of the blades.

Detailed Description of Preferred Embodiments

Now some embodiments of the disclosure will be described with reference to the drawings.

The disclosure is directed to provide a vortex finder for a cyclonic separator for at least enhancing the separation ability of the cyclonic separator, as well as a cyclonic separator comprising such a vortex finder. The cyclonic separator according to the disclosure can be used for separating solid particulates and/or liquid droplets from a gas. A particular form of the cyclonic separator is a water (or liquid) separator which is mainly used for separating water (or liquid) from a gas (for example, air) .

An exemplary vortex finder 100 of the disclosure is schematically shown in Figures 1 and 2. As can be seen from these figures, the vortex finder 100 comprises a hollow cylinder 1 defining a vertically extending central axis O of the vortex finder 100 and formed with a vertical passage 2 therethrough, a top flange 3 extending transversely outwards from a top end of the cylinder 1, a bottom baffle 4 extending transversely outwards from a bottom end of the cylinder 1, a tubular wall 5 surrounding a lower part of the cylinder 1, and a plurality of blades 6 extending radially and connected between the lower part of the cylinder 1 and the tubular wall 5.

The vortex finder 100 is preferably an integrated member, for example, formed of plastic by molding. For high temperature applications, the vortex finder 100 may be formed of metal or other heat-stable materials.

Some portions or all of the outer surface of the vortex finder 100 may be covered with a hydrophobic material to increase the water separating ability. For example, all of the outer surface of the vortex finder 100, except the upper surface of the top flange 3, may be covered with a hydrophobic material.

The top flange 3 may have a circular outer periphery as illustrated in Figure 1. The outer periphery of the tubular wall 5 may have a diameter slightly smaller than that of the outer periphery of the top flange 3. The vortex finder 100 can be fixed in a tube at its top flange 3 to mount the vortex finder 100 inside the tube, and thus the top flange 3 functions as a mounting part for the vortex finder 100. It is understood that, since the top flange 3 mainly functions as a mounting part, it may alternatively have other shapes instead of circular.

The top flange 3 and the bottom baffle 4 face towards each other in the axial direction. The bottom baffle 4 has an outer diameter smaller than the inner diameter of the tubular wall 5 so that there forms a circular bottom gap 7 between the bottom edge of the tubular wall 5 and the outer periphery of the bottom baffle 4.

The bottom baffle 4 may be completely surrounded by the tubular wall 5. For example, the bottom surface of the bottom baffle 4 is substantially flush with the bottom edge of the tubular wall 5 as illustrated in Figure 2. Alternatively, the bottom baffle 4 may be partially or totally exposed from the bottom edge of the tubular wall 5 in the axial direction.

The blades 6 are evenly arranged around the cylinder 1. The total number of the blades 6 may be 8 to 16. Between the plurality of blades 6 and the top flange 3, a circular space 8 is formed around an upper portion of the cylinder 1. The circular space 8 mainly functions to form a vortex flow path in the vortex finder 100 as will be described below.

The vortex finder 100 can be used for forming a cyclonic separator. In an exemplary embodiment shown in Figures 3 and 4, an exemplary cyclonic separator of the disclosure comprises a casing and a vortex finder 100, as described above, mounted in the casing. The casing mainly comprises a substantially vertical tube 101 with a lower closed end 102 and an upper open end 103. The vortex finder 100 is arranged in the tube 101 at a location higher than the lower end 102, leaving a collection chamber 104 between the lower portion of the vortex finder 100 and the lower end 102. The vortex finder 100 is substantially coaxial with the tube 101, with the outer periphery of the top flange 3 fixedly sealed to the inner surface of the tube 101. An inlet 105 is transversely mounted to the tube 101 to be open and facing towards the circular space 8. The inlet 105 has a transverse central axis that does not intersect the central axis O of the vortex finder 100, that is, offset from the central axis O, so that a rotational flow or vortex will be formed in the circular space 8 once there is gas introduced into the tube 101 via the inlet 105. An outlet (not shown) may be assembled to the upper end 103 or formed by the upper end 103 to be in fluid communication with the upper end of the passage 2.

Since the outer periphery of the tubular wall 5 has a diameter smaller than that of the outer periphery of the top flange 3, there is a peripheral gap 9 between the inner surface of the tube 101 and the outer periphery of the tubular wall 5, as illustrated in Figure 3.

As shown in Figures 3 and 4, a mixed flow is fed into the cyclonic separator via the inlet 105. The mixed flow is composed mainly of a gas in which solid particulates and/or liquid droplets are entrained. In the cyclonic separator, the gas will first flow through the circular space 8 to form a rotational flow or vortex in the circular space 8 due to the offset configuration of the inlet 105 with respect to the tube 101. Under the centrifugal force generated by the rotational flow, some of the solid particulates and/or liquid droplets which have higher densities than the gas will move radially outwards to hit the inner surface of the tube 101, then move down along the inner surface of the tube 101 through the peripheral gap 9, and then fall down towards the bottom of the collection chamber 104. A small fraction of the gas also flows through the peripheral gap 9 into the collection chamber 104.

Then the main portion of the rotating mixed flow reaches the blades 6 and is separated by the blades 6 into a plurality of small flows. Under the guidance of the blades 6, the small flows move towards the tubular wall 5, the bottom baffle 4 and the bottom gap 7. After hitting the tubular wall 5 and the bottom baffle 4, some solid particulates and/or liquid droplets in the flows will move along the tubular wall 5 and the bottom baffle 4, then move through the bottom gap 7, and then fall down towards the bottom of the collection chamber 104.

The small flows of gas also move downwards through the bottom gap 7 into the collection chamber 104. In the collection chamber 104, the small flows of gas and the fraction of gas that passes through the peripheral gap 9 move radially inwards to the bottom end of the passage 2 and then move upwards into the passage 2. That is to say, the flows of gas in the collection chamber 104 turn their moving direction by 180°. In this turning, the remaining solid particulates and/or liquid droplets in the flows will be thrown off to fall down in the collection chamber 104. Now the upward flow in the passage 2 is composed nearly only of the gas with little or no solid particulates or liquid droplets, so the gas can be called clean gas. The clean gas will pass through the passage 2 and then leave the cyclonic separator via the outlet.

The movements of the mixed flow in the cyclonic separator is schematically indicated in Figure 3 and 4 by arrows.

A drain port (not shown) may be mounted to the collection chamber 104 or formed by a portion of the collection chamber 104 for discharging the liquid (for example, water) and/or particulates gathered in the collection chamber 104. The drain port may be coupled to a drain line in which a normally closed valve may be arranged for discharging the collected liquid and/or particulates periodically. Alternatively, the collection chamber 104 or a portion of it may be formed as detachable or openable so that the gathered liquid and/or particulates can be removed from the cyclonic separator.

It can be seen that the vortex finder of the disclosure provides two main separation effects to the mixed flow, a centrifugal separation effect provided by the rotational flow in the circular space 8 and a baffle separation effect provided by the tubular wall 5, the blades 6 and the bottom baffle 4. A third minor separation effect is provided by turning the direction of flows by 180° in the collection chamber 104. Due to these effects, the vortex finder of the disclosure has a high separation efficiency. Further, the purity of the gas discharged via the outlet is so high that no filter needs to be incorporated in the cyclonic separator for most applications, and the cyclonic separator of the disclosure may be called a two-stage separator since it includes two stages of separation, centrifugal separation and baffle separation.

For facilitating the solid particulates and/or liquid droplets to move along the bottom baffle 4 into the collection chamber 104, the upper surface of the bottom baffle 4 is designed to be downwardly oblique from its inner periphery to its outer periphery, as shown in Figure 5. With two main factors, first, smooth moving of the solid particulates and/or liquid droplets, and second, providing baffle to the flows, taking into consideration, the oblique angle α is determined to be preferably in the range of 5° to 20°.

The outer diameter of the bottom baffle 4 is determined so that, on the one hand, the bottom baffle 4 can provide sufficient baffle to the flows, and on the other hand, leaving the bottom gap 7 to be large enough to avoid large pressure drop of the flows when they pass through the bottom gap 7.

Turning to the blades 6, considering both the factors of increasing the separation efficiency while avoiding large pressure drop, they are designed to be oblique with respect to radial directions, as shown in Figure 6. Each blade 6 has a front main surface facing the incoming flow and an back opposite main surface. The orientation and configuration of the blades 6 will be described with reference to Figures 7 and 8 in which one blade 6 is taken as an example of all of them.

Each blade 6 has a blade root 6a connected to the cylinder 1, a blade tip 6b connected to the tubular wall 5, a blade top 6c facing substantially upwards, and a blade bottom 6d facing substantially downwards.

The blade bottom 6d may be substantially horizontal, and the blade bottoms 6d of all the blades 6 may lie substantially in the same horizontal plane.

In one embodiment (not shown) , the blade top 6c is substantially horizontal, while in another embodiment (see Figure 8) , the blade top 6c is downwardly oblique from the blade root 6a to the blade tip 6b by an angle β which is preferably in the range of 5° to 30°.

As shown in Figure 8, let the height of the vortex finder 100, as measured from the top surface of the top flange 3 to the bottom surface of the bottom baffle 4, be H1 and the height of the tubular wall 5 be H2, then the height H3 of the blade 6 is smaller than H2. For example, H3= (0.5 to 0.85) *H2. The height H2 of the tubular wall 5 may be in the range of (0.3 to 0.6) *H1.

In the condition that the blade top 6c is horizontal, the height H3 of the blade 6 is substantially constant so that it can be measured at any part of the blade. In the condition that the blade top 6c is oblique, the height H3 of the blade 6 may be measure at the blade root 6a, as shown in Figure 8.

The blade 6 extends obliquely with respect to the central axis O so that the blade top 6c and the blade bottom 6d are not coincident in the axial direction of the vortex finder 100. More specifically, the blade bottom 6d lies ahead of the blade top 6c in the direction opposite to the incoming rotational flow direction R, and the blade bottom 6d may be offset by an offset angle with respect to the blade top 6c in the direction opposite to the incoming rotational flow direction R when looking in the axial direction.

Some exemplary embodiments showing the locations of the blade top 6c and the blade bottom 6d are schematically shown in Figures 9 to 12 which are all taken from above in the axial direction of the vortex finder 100.

In an embodiment shown in Figure 9, the center line of the blade top 6c is straight when looking in the axial direction and the extension of it intersects the central axis O, and the center line of the blade bottom 6d is also straight line when looking in the axial direction and the extension of it also intersects the central axis O, with an offset angle θ formed between the blade top 6c and the blade bottom 6d, as measured between the two center lines with the central axis O as a reference. The blade bottom 6d is offset by the offset angle θ from the blade top 6c in the direction opposite to the incoming rotational flow direction R.

In an embodiment shown in Figure 10, the center lines of the blade top and bottom 6c and 6d are both straight when looking in the axial direction, and neither of the extensions of them intersects the central axis O, with the blade bottom 6d being offset from the blade top 6c by an offset angle in the direction opposite to the incoming rotational flow direction R.

In an embodiment not shown here, the center lines of the blade top and bottom 6c and 6d are both straight when looking in the axial direction, the extension of one of them intersecting the central axis O while the extension of the other one not intersecting the central axis O, with the blade bottom 6d being offset from the blade top 6c by an offset angle in the direction opposite to the incoming rotational flow direction R.

It is understood that, for a blade 6 having straight center lines of the blade top and bottom 6c and 6d when looking in the axial direction and the center lines being offset with reference to the central axis O, the blade 6 should be curved or twisted.

In an embodiment shown in Figure 11, for an alternative curved blade, the center lines of the blade top and bottom 6c and 6d are both curved when looking in the axial direction, with an offset angle between them.

In an embodiment not shown here, one of the center lines of the blade top and bottom 6c and 6d is curved while the other one is straight when looking in the axial direction, with an offset angle between them.

The offset angle between the blade top and bottom 6c and 6d may be defined as the difference in the angular positions of their center lines when looking in the axial direction.

In the condition that the blade top and bottom 6c and 6d each have a straight center line when looking in the axial direction, the offset angle may be measured between two vertical planes in which the two straight center lines lie respectively.

In the condition that one of the blade top and bottom 6c and 6d has a straight center line and the other one has a curved center line, the offset angle may be measured between a vertical plane in which the straight center lines lies and a vertical plane which is tangent to the curved center line at a point on the curved center line (for example, the midpoint of the curved center line, a point of the curved center line at the blade root or tip, or any other suitable points) .

In the condition that the blade top and bottom 6c and 6d each have a curved center line when looking in the axial direction, the offset angle may be measured between two vertical planes which are tangent to the two curved center lines respectively at a point on each curved center line (for example, the midpoint of each curved center line, a point of each curved center line at the blade root or tip, or any other suitable points) .

In general, the offset angle, no matter at which point it is measured, is in the range of 5° to 30°, preferably 10° to 20°, and most preferably about 15°.

Other manners for defining and measuring the offset angle between the blade top and bottom 6c and 6d may also be used here.

In an embodiment shown in Figure 12, the blade 6 is flat (or planar) , the center lines of the blade top and bottom 6c and 6d are both straight when looking in the axial direction, and neither of the extensions of them intersects the central axis O. For a flat blade 6, there may be no offset angle between the blade top 6c and the blade bottom 6d.

Embodiments in which other positional and angular locating manners of the blade top and bottom 6c and 6d are incorporated can also be designed by those skilled in the art. The design can be performed by means of experiments, computer simulation, or the like to achieve synthesized optimization of increasing separation efficiency and reducing pressure drop across the vortex finder 100. The dimensions and locations of other parts of the vortex finder 100 are also optimized for achieving the synthesized optimization.

According to the disclosure, the vortex finder can provide both centrifugal separation and baffle separation effects to a mixed flow of fluid for separating solid particulates and/or liquid droplets from a gas. Separation efficiency is high, while pressure drop across the vortex finder can be suppressed. Meanwhile, the vortex finder configured as described above has a compact contour.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the disclosure. The attached claims and their equivalents are intended to cover all the modifications, substitutions and changes as would fall within the scope and spirit of the disclosure.

Claims

A vortex finder (100) for a cyclonic separator comprising:

a hollow cylinder (1) defining a vertically extending central axis (O) and formed with a vertical passage (2) therethrough;

a top flange (3) extending transversely outwards from a top end of the cylinder (1) ;

a bottom baffle (4) extending transversely outwards from a bottom end of the cylinder (1) ;

a tubular wall (5) surrounding a lower part of the cylinder (1) ; and

a plurality of blades (6) extending radially and connected between the cylinder (1) and the tubular wall (5) , a circular space (8) being formed around an upper portion of the cylinder (1) between the plurality of blades (6) and the top flange (3) .
The vortex finder of claim 1, wherein the bottom baffle (4) has an outer diameter smaller than the inner diameter of the tubular wall (5) so that a circular bottom gap (7) is formed between the bottom edge of the tubular wall (5) and the outer periphery of the bottom baffle (4) .
The vortex finder of claim 1 or 2, wherein a bottom surface of the bottom baffle (4) is substantially flush with a bottom edge of the tubular wall (5) in the axial direction.
The vortex finder of any one of claims 1 to 3, wherein the outer periphery of the tubular wall (5) has a diameter smaller than that of the outer periphery of the top flange (3) .
The vortex finder of any one of claims 1 to 4, wherein an upper surface of the bottom baffle (4) is downwardly oblique from its inner periphery to its outer periphery with an oblique angle (α) which is in the range of 5° to 20°.
The vortex finder of any one of claims 1 to 5, wherein each blade (6) has a blade root (6a) connected to the cylinder (1) , a blade tip (6b) connected to the tubular wall (5) , a blade top (6c) facing substantially upwards, and a blade bottom (6d) facing substantially downwards, and the blade bottom (6d) lies ahead of the blade top (6c) in the direction opposite to an incoming rotational direction of a flow to be formed in the vortex finder.
The vortex finder of claim 6, wherein the blade bottom (6d) of each blade (6) is substantially horizontal, and all the blade bottoms (6d) are substantially coplanar; and

wherein the blade top (6c) of each blade (6) is substantially horizontal; or

wherein the blade top (6c) of each blade (6) is downwardly oblique from the corresponding blade root (6a) to the blade tip (6b) by an angle (β) which is in the range of 5° to 30°.
The vortex finder of claim 6 or 7, wherein the blade bottom (6d) is offset by an offset angle with respect to the blade top (6c) in the direction opposite to the incoming rotational direction when looking in the axial direction, the offset angle being in the range of 5° to 30°.
The vortex finder of claim 8, wherein at least one of the center line of the blade top (6c) and the center line of the blade bottom (6d) is a straight line when looking in the axial direction.
The vortex finder of claim 8, wherein the center line of the blade top (6c) and the center line of the blade bottom (6d) are both straight lines when looking in the axial direction; optionally, the extensions of both the center lines intersect the central axis; or the extension of one of the center line intersects the central axis while the extension of the other center line does not intersect the central axis; or neither one of the extensions of the center lines intersects the central axis.
The vortex finder of claim 8, wherein at least one of the center line of the blade top (6c) and the center line of the blade bottom (6d) is a curved line when looking in the axial direction.
The vortex finder of claim 6 or 7, wherein each blade (6) is a planar blade.
The vortex finder of any one of claims 6 to 11, wherein each blade (6) is a curved blade.
The vortex finder of any one of claims 1 to 13, wherein the number of the blades (6) is 8 to 16, and the blades (6) are evenly arranged around the cylinder (1) .
The vortex finder of any one of claims 1 to 14, wherein some portions or all of the outer surface of the vortex finder is covered with a hydrophobic material.
A cyclonic separator comprising:

a casing comprising a substantially vertical tube (101) with a lower closed end (102) and an upper open end (103) ;

a vortex finder (100) of any one of claims 1 to 15 arranged in the tube (101) , with the top flange (3) of the vortex finder fixedly sealed against the inner surface of the tube (101) ;

an inlet (105) transversely mounted to the tube (101) , the inlet (105) facing towards the circular space (8) and directed in a direction offset from the central axis of the vortex finder; and

an outlet in fluid communication with an upper end of the passage (2) .