GB2271520A

GB2271520A - Cyclone separator

Info

Publication number: GB2271520A
Application number: GB9319814A
Authority: GB
Inventors: Friedemann Ingwalt
Original assignee: Dietrich Fette
Current assignee: Dietrich Fette
Priority date: 1992-10-02
Filing date: 1993-09-24
Publication date: 1994-04-20
Also published as: FR2696361A1; GB9319814D0; DE4233174A1

Abstract

To increase the separation effect and reduce the pressure losses, the tangential unfiltered gas inlet 7 of a cyclone separator is formed by a helical inlet conduit, which is open towards the separator, the width b, B of said conduit increasing towards the inner end of the conduit and the height H, h thereof decreasing towards the inner end of the conduit. The upper and lower walls of the inlet conduit extend inclinedly when the cross-section of the conduit is substantially trapezoidal. <IMAGE>

Description

i CYCLONE SEPARATOR 2271520 The invention relates to a cyclone separator

having a tangential unfiltered gas inlet, an upper purified gas outlet and a lower solids discharge means.

In known cyclone separators of such type, a socalled compression flow is produced immediately behind the inlet; the resultant displacement of the turbulent flow thereby produces disadvantageous cross-mixings.

These disadvantages are to be eliminated by the invention; in consequence, the basic object of the invention is to improve a cyclone separator of the above type so that an increased separation effect occurs, yet there is also a reduced pressure loss.

To achieve this object as claimed in the invention, provision is made for the inlet to be adapted as a helical inlet conduit, which is open towards the cyclone separator, the height of said conduit decreasing towards the end of the conduit and the width thereof increasing towards the end of the conduit. Accordingly, the longitudinal central axis of the inlet conduit does not lie substantially in a normal plane relative to the cyclone separator; rather, the longitudinal central axis of the inlet conduit follows a helical line, the spacing of which from the upper end of the cyclone separator gradually increasing. Such an arrangement also ensures that the displacement, which occurs through the inflow through the unfiltered gas inlet, ceases or only occurs to an extent which is no longer effective for practical purposes.

The inlet conduit is also advantageously provided with a particular crosssectional configuration, such r being a configuration which is at least substantially trapezoidal, so that the longer of the two (imaginary) sides of the trapezium, which extend parallel to each other, faces the cyclone separator. This measure also contributes towards dealing with the cross-mixing in the above- mentioned sense.

H6wever, a helical configuration is advantageously selected which (when seen in the plan view of the cyclone separator) surrounds the body of the cyclone separator only substantially over a maximum of about 3600, such that the height of the conduit reduces to the value 0 towards the end of the inlet conduit.

It may be mentioned that a strict trapezoidal configuration in the abovementioned sense is not absolutely necessary; rather, the lower and/or upper lateral walls of the inlet conduit may also have a rounded configuration.

It is also advantageous when the upper portion, i.e. the lid, of the cyclone separator does not extend in a flat manner above the inlet conduit. Rather, to avoid frictional forces and a resultant secondary flow inwardly orientated at the lid, it is advantageous to taper the casing of the cyclone separator in the upper region, preferably in the region of the helical inlet conduit, in an upwardly conical manner.

The invention also seeks to improve and modify the immersion tube so as to comply substantially with the initially described requirement for an increased separation effect. In order to meet these requirements, the immersion tube is provided with a predetermined cross-sectional configuration, preferably so that the cross-section of the immersion tube is roughly 1.5- to 2- 1 times the cross-section of the inlet conduit at the inf low location of this conduit. At the same time, it may also be advantageous to provide the lower end of the immersion tube with slot-like recesses, which extend at least roughly in the direction of the immersion tube and have open edges.

These modifications to the immersion tube have substantially the following advantageous effects:

The inwardly orientated radial velocity distribution, or respectively, above all, the reduction in the high flow velocities in the direction towards the immersion tube inlet, and the associated reduction in the entrainment of coarse particles.

A reduction in the separation particle diameter is generally achieved; the separation particle diameter thereby constantly decreases for the gas components which flow through the above-mentioned recesses into the immersion tube. and also for the gas components which flow through the lower opening of the inlet. A distinctly smaller, minimal separation particle diameter is achieved.

Furthermore, the turbulence component which increases the pressure loss is reduced in the immersion tube, in that the turbulence effects are retarded radially by means of gas flows entering the recesses. It is important, therefore, that this advantageous alignment of the flow is achievable without additional, disadvantageous frictional effects at the walls, but is achievable by kinetic effects of the split flow.

Further details of the invention are explained with reference to the drawing, in which two embodiments b of the invention are illustrated. In the drawing:

Fig. 1 illustrates a cyclone separator; Fig. 2 illustrates the upper half of the cyclone separator of Fig. 1, on an enlarged scale, the right-hand portion being shown in cross-section; Fig. 3 illustrates a modified embodiment of a cyclone separator; and Fig. 4 is a plan view of the separator of Fig. 3.

The housing of the cyclone separator substantially comprises an upwardly conically tapering upper portion 1, a downwardly extending cylindrical portion 2 and a lower portion 3, which corresponds in size to the portion 1, is also conical and is provided with a lower connection pipe 4 serving as a solids discharge means. A roughly cylindrical immersion tube 5, which extends substantially beyond the portions 1 and 2 and has a connection pipe 6 at its upper end serving as a purified gas outlet, is provided internally of the housing centrally relative to the portions 1 to 3.

The unfiltered gas inlet is situated at 7 and is formed by an inlet conduit 8 having a trapezoidal crosssection; this conduit surrounds the portion 1 helically from above (upper edge of portion 1) towards the lower edge of portion I - when viewing the cyclone separator of the drawing and in respect of the circumference (plan view of the separator) - over about 2700, but an arc of about 300 - 3300 may also be selected. The inlet conduit 8 is placed to some extent on the portion 1, but it is open towards the interior of the separator (cf. also the cross-sectional view of Fig. 2, right-hand half).

At the inflow location 7 extending tangentially relative to the separator, the inlet conduit 8 has a height H, plus a greater width bl and a smaller width b2 h when the cross-section is trapezoidal. These dimensions constantly vary towards the centre line 9. While the inlet conduit still has a height h (H greater than h) and greater widths B1 and B2 in the cross-sectional view (Fig. 2, right-hand half), but still has a trapezoidal configuration, the inlet conduit 8 in the centre line 9 passes smoothly into the conical wall of portion 1. This particular configuration of the inlet conduit 8 provides an extremely smooth inflow without variable displacement, separation and cross-mixing effects.

In addition, the lower end of the immersion tube 5 extends to the upper edge of portion 3 and beyond the region of portion 2 provided with slots 10, which have open edges and the width of which gradually decreases towards portion 1. These slots 10 provide the above-mentioned turbulence reducing effect.

In the cyclone separator of Figs. 3 and 4, the upper portion I has been replaced by a cylindrical portion 11. However, the inflow location also has a trapezoidal configuration at 7 here; the height H gradually reduces to the value 0 towards the centre line 9, while the widths increase in accordance with Figs. 1 and 2. In addition, the embodiment of Figs. 3 and 4 has a further inlet connection pipe 12, which is connected at the inlet end and improves the tangential inflow.

It may also be mentioned that the inside diameter of the immersion"tube 5 is about 1.5-times greater than the inlet conduit 8 at the location 7.

Furthermore, the cross-sections of the inlet conduit 8 are also preferably selected so that the crosssection of said conduit does not decrease substantially despite the above-mentioned width and height variations (roughly for the first circumferential region of 18011); once the inlet conduit has completed an arc of 18011, a very gradual extension of the inlet conduit 8 upwardly and downwardly follows. As mentioned, the height of the inlet conduit 8 has reduced to 0 in the region of the centre line 9.

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Claims

1. A cyclone separator having a tangential unfiltered gas inlet, an upper purified gas outlet formed from an immersion tube disposed centrally internally of the separator, and a lower solids discharge means, wherein the unpurified gas inlet is formed by a helical inlet conduit, which is open towards the separator, the width of said conduit increasing towards the end of the conduit and the height thereof decreasing towards the end of the conduit.

2. A cyclone separator as claimed in claim 1, wherein the inlet conduit is defined upwardly and downwardly by inclined walls so that, when the crosssection of the conduit is at least substantially trapezoidal, the longer of the two parallel sides of the trapezium faces the separator.

3. A cyclone separator as claimed in claim 1, wherein the inlet conduit surrounds the separator over a maximum of about 3600.

4. A cyclone separator as claimed in claim 3, wherein the inlet conduit surrounds the separator over about 2700.

5. A cyclone separator as claimed in claim 1, wherein the first portion of the inlet conduit, encircling the separator over about 1800, has a crosssection of substantially the same dimension.

6. A cyclone separator as claimed in claim 1, wherein the upper portion of the separator tapers upwardly in a cone-shaped or conical manner.

7. A cyclone separator as claimed in claims 1 and 6, wherein the inlet conduit practically extends beyond the height of the cone-shaped or conical portion.

8. A cyclone separator as claimed in claims 1, 6 and 7, wherein the immersion tube extends beyond the coneshaped or conical portion and beyond a cylindrical portion of the separator housing communicating with said conical portion at its lower end.

9. A cyclone separator as claimed in claim 1, wherein the immersion tube is provided at its lower end with recesses which have open edges.

10. A cyclone separator as claimed in claim 9, wherein the recesses extend as slots at least substantially in the direction of the immersion tube.

11. A cyclone separator as claimed in claim 10, wherein the slot width decreases upwardly.

12. A cyclone separator as claimed in claims 1 and 2, wherein the shorter of the two sides of the trapezium, which are parallel to each other, coincides with the external wall of the separator housing at the end of the conduit.

13. A cyclone separator as claimed in claim 1, wherein the diameter of the immersion tube is roughly 1.5- to 2-times the cross-section of the inlet conduit at the inflow location of this conduit.

14. A cyclone separator, substantially as hereinbefore described with reference to the accompanying drawings.

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