US2033470A - Cyclone separator - Google Patents

Description

March 10,- 193 J. H. KEENAN CYCLONE SEPARATOR Filed Aug. 30, 1933 Z If k8 2 Sheets-Sheet l INVENTOR Mam ATTORNEY March 10,

1936. J. H. KEENAN CYCLONE SEPARATOR Filed Aug. 30, 1933 2 Sheets-Sheet 2 l2 9 u 7 :T I

INVENTOR ATTORNEY Patented Mar. 10, 1936 UNITED STATES Joseph H. Keenan, Hoboken, N. 3., asslgnor to Jabez Burns & Sons, Inc., New York, N. Y., a corporation of New York Application August 30, 1933, Serial No. 687,401

Claims.

This invention relates to improvements in devices for separating particles of denser substance from liquid or gas streams by swirling the stream and its particles in a free or constrained vortex. I shall refer to all such devices, whether for c'om-' pletely separating particles and stream or merely for concentrating the particles withina portion of duct of round or approximately square cross-seciii The common type of cyclone separator consists of the following parts: a cylinder into which the particle-laden stream is introduced through a tion, the outside wall of the duct being tangent to the cylinder wall at entrance; a conical chamber below the cylinder for collecting or leading off the separated material; a central outlet pipe, attached to the top of the cylinder and projecting'down some distance into it, leading directly to the;

atmosphere or tea duct.

There are, of course, many variations on this common type of design. In some cases the inside wall of the incoming stream, instead of the outside wall, is made tangent to the cylinder. This arrangement. usually involves a departure from the usual circular cross-section of the cylinder toward a spiral cross-section. In some cases there completely fllls the vortex chamber, (that is, it is not bounded at the top by a liquid surface) there is a pressure gradient, the pressure decreasing toward the center of the vortex. This pressure gradient provides the radially inward accelerations to the stream which are necessary to the swirling motion. If, as in the usual cyclone separator, the stream leaves the cylinder or separating chamber through a central hole atthe top and passes directly to the atmosphere or tea duct then the minimum drop in static pressure across the most perfect collector of this type would be the pressure gradient integrated along a line passing through the vortex center between theinlet opening and the rim of the outlet hole.

The pressure drop along the streampath in a vortex results in an increase in the kinetic energy of the stream which, except for friction eflfects, is an essentially reversible process; that is, the kinetic energy could, presumably, be reduced again to the original or entrance magnitude with a rise in pressure equivalent (except for friction) tothe drop experienced in the separating vortex.

My invention includes devices for recoveringa large part of the pressure drop through the separating chamber byreducing the velocity of the In some designs guide vanes stream after it leaves the separating cylinder in a properly designed chamber or passage. In its preferred form its consists of two parallel horizontal plates, substantially circular in plan view and of about the same diameter as the separating cylinder. The lower plate has a central hole which fits the outlet pipe of the separating cylinder. The fluid stream passes from the outlet pipe of the separating cylinder into the space between the two plates and flows spirally outward until it reaches the atmosphere. If the device is intended to discharge into a duct instead of into the atmosphere, a scroll-type passage may be arranged around the perimeters of the top plates which will lead off the stream tangentially into a duct.

The stream enters this top passage with an angular momentum per unit time which is smaller than the angular momentum at the entrance to the separating'cylinder by the wall friction moments only. This angular momentum results in a vortex in the top passage similar to the one in the separating chamber except that the direction of flow is spirally outward instead of spirally inward. The usual vortex pressure gradient is established in this top passage and the fluid stream flows from the low pressure region at the small radius from the center of the vortex at n which it enters to the higher pressure region at the large radius at which it leaves. The pressure drop across the whole device is thus smaller than the pressure drop across the ordinary cyclone separator by the pressure rise which occurs in the top chamber.

The process of increasing the pressure along the path of a fluid stream by reducing its velocity I shall hereafter refer to as diflusion, and the passage or chamber in which the process'is carried out I shall call a diffuser, a diffusing passage, or a diflusing chamber. A diiIuser is essentially a reversed nozzle since in a nozzle the stream increases in velocity and decreases in pressure in the direction of flow while in a difiuser the stream decreases in velocity and increases in pressure in the direction of flow.

It is interesting to follow the pressure distribution through a separator fitted with a diffusing passage which discharges to the atmosphere. The pressure in the exit opening is necessarily atmospheric. The pressure in the connecting hole between the separating cylinder and the diflfusing passage is lower than atmospheric because the vortex in the diffusing passage sets up a higher pressure at its periphery than in the center. If this were an ordinary separator the pressure in this hole would be atmospheric, and the inlet pressure, and all other pressures which the blower of the system must pump against, would be higher by an amount equal to the vacuumobtained .in--the connecting hole of my device. I I

The utility of this device consists in the reduction in power consumption in the fan or compressor which provides the pressure difi'erential for overcoming the various frictional resistances in the path of the stream. It is obvious that any device which reduces the pressure drop in any part of the flow path will reduce the power input to the fan almost in direct proportion for the same rate of fluid flow.

I am aware that some manufacturers of cyclone separators design the top of the separator so that the fluid leaves the central exit pipe tangentially and in the direction of rotation. This results in a limited utilization of the kinetic energy of the stream leaving the exit pipe, but it does not involve the compression of the stream to higher pressure by reducing velocity. Neither sort may be emphasized by pointing out the in herent reversibility of my combination. A separator may be fitted with a diffusing passage and anoutlet scroll, the discharge cross-section of which may be made equal to the inlet area of the separating cylinder. If a stream of frictionless fluid were introduced into the separating cylinder at a certain pressure it would leavevthe outlet scroll at the same pressure. "Across an ordinary separator, on the other hand, thepressure of the fluid would have decreased by the integrated pressure gradient through the separating vortex. In this new design the fluid flow could just as well have been reversed in direction, entering through the top scroll opening and leaving through the opening in the lower cylinder wall. The diflusing passage has now become the separating chamber, and the separating chamber has become the dififusing passage. Such reversal of flow would be impossible in the ordinary separator because the entering fluid in the reversed case, having no rotation, would produce no vortex and would do no separating.

This invention can be modified by inserting vertical guide vanes in the diffusing passage to aid the diifusion process or to reduce the length of the fluid path through the'diflusion passage.

In the accompanying drawings: Fig. 1 shows my invention in its simplest form and arranged to discharge the stream directly to the atmosphere.

Fig.2isatransversesectiononline2-2 of Fig. 1.

Fig. 3 shows experimental data on the saving realized from the use of the device shown in Fig. l. V a

Fig. 4 shows my invention with two modifications, first, a conical connecting piece between the cylinder outlet pipe and the diffusing passage and, second, guide vanes in the diffusing passage to aid diifusion.

Fig.5isatransversesectiononlineS-iot Fig. 4. 1

Fig. 6 shows my invention arranged to discharge into a duct.

Fig.7isatransversesectiononline1-4I of Fig. 6.

Fig.8isaseparatorarrangedtopermitthe stream to flow in either direction.-

Flg.9isatransversesectiononline i-l oi Fig. 8.

Fig. 10 shows a modification of Fig. l with conical instead of flat diffusing plates.

The separator shown in Figs. 1 and 2 comprises vertical cylinder l in which the denser particles are separated from the fluid stream which enters through approach pipe 2, lower conical hopper 3 for collecting or leading oil the denser separated material, discharge pipe 4 through which the stream passes on its way to diffusing passage 8, which is bounded by circular plates 6 and I resting on supports 8. Plates 6 and I need not be horizontal but may be formed into substantially parallel cones with apexes at the top or at the bottom of the cone. Slight departures from parallelism between 6 and I will not necessarily destroy the efifectiveness of the diifusion passage and in some instances might be advantageous.

' The distance between plates (or cones) 6 and I for minimum pressure drop across the entire device must be determined in each instance by experiment. Fig. 3 shows experimentally determined pressure drops plotted against distance between plates 6 and I for a separator, similar to that shown in Figs. 1 and 2, the separating cylinder of which was 72 inches diameter and the outlet pipe 27 inches diameter. The ordinate is pressure drop in inches of water, the abscissa is distance between plates 6 and I in inches. Line Illa shows the pressure drop for the separator with only a weather shield over the outlet pipe. Line lllb showsthe pressure drop for the same flow through the same separator fltted with plates 6 and 1. A maximum gain of about 30% is realized in this case when the plates are two inches apart.

The separator shown in Figs. 4 and 5 is similar to that shown in Figs. 1 and 2 except for conical connecting piece 9 and guide vanes I0. Connecting piece 9 guides the fluid stream more smoothly into the diflfusing passage and reduces the eddy disturbances which may be caused by the sharp corner between discharge pipe 4 and plates 6 shown in Fig. 1. The connecting piece need not, of course, be conical in shape-but may have a curved cross-section. The relative ease .with which the conical piece may be manufactured will recommend it even above designs which might give slightly smoother flow. The guide vanes are desirable to promote diffusion under certain circumstances, particularly in cases where the tangential component of the velocity would otherwise be high where the fluid passes out from between the plates.

In Figs. 6 and 7 is shown a separator with diffusing passage I l fitted with scroll II. The scroll collects the stream leaving the diffuser and leads it to exit opening I; which is approximately of the samecross-section area as separator inlet H. A duct may be connected to. the scroll at I 3 to lead the stream oil to other apparatus or to an outlet pipe.

A separator arranged for flow in either direction is shown in Figs. 8 and 9. It comprises lower cylinder I5 and upper cylinder I6 connected by central pipe I! and conical pieces It. The lower cylinder is fitted with conical hopper I! to lead oil or tocollect separated material. The upper cylinder is fitted with conical hopper 2B for the same purpose. Hopper 20 surrounds pipe I I and through which separated material may pass into '15 ,vided with acentral the hopper. Similarly in the top cylinder is fltted plate 25 around the edge of which is left clearance space 26. Plates 22 and 25 are not essential to my invention, but they aid diflusion when diffusion is occurring in their respective cylinders. In the absence of plates 22 and 25 the fluid in the hopper, being retarded by wall friction may be reduced in velocity to the point where its kinetic energy is inadequate to permit it to flow outward against the, pressure gradient. A reverse flow inward would then be set up within the hopper. Fluid flowing inward must ultimately be carried outward again by friction drag from the main diifusing stream, and this process reduces the momentum of the diffusing stream and reduces the rise in pressure realized in the diffusion process. Plates 22 and 25 prevent transfer of momentum from the main stream to the fluid in the hopper. The lower cylinder is provided with opening 21 and the upper with opening 28 of equal area. Both openings may be connected with ducts.

Now, if the fluid stream is led into opening 21 separation of denser particles will occur in the vortex set up in cylinder the stream will pass from cylinder I5 through pipe I I to cylinder IS in which it will flow outward against the vortex pressure gradient to opening 28. The device will work equally well if the direction of flow is reversed, the stream entering opening 28 and leaving through opening 21, separation occurring in cylinder l6 and diil'usion in cylinder IS.

The device shown in Figs. 8 and 9 may be used in cases where separation of denser particles is desired from a stream which flows alternately in opposite directions, as in certain regenerative processes in industry.

Fig. 10 shows a somewhat better design for outdoor use than Fig. 1 in which plates 36 and 31 are coned instead of flat asare plates 6 and 1 in Fig. 1, but the operation is the same.

The invention claimed is:

1. A difluslng passage comprising two substantially parallel and horizontal plates in combination with a cyclone separator, including a. separating cylinder and a centrally disposed exit pipe, the lower plate being in the form of an annulus supported above the top of the separating cylinder and attached to the exit pipe of the separating cylinder.

2. A difl'using pasage comprising two substantially parallel and horizontal plates separated'by vertical guide vanes in combination with a cyclone separator, including a separating cylinder and a centrally disposed exit pipe, the lower plate being in the form of an annulus which is attached to the exit pipe of the separating cylinder.

3. A diflusing passage comprising two substantially parallel conical plates in combination with a cyclone separator, the lower cone being prohole, and being attached to separating cylinder so that is concentric with the exit said conical plates being close together to insure the exit pipe of the the hole in the cone pipe of the cylinder, disclosed substantially difiusion.

4. A diflusing passage comprising two substantially parallel plates, a peripheral chamber surrounding these plates, communicating with the space between them and open at one point on the periphery where connectionvmay be made with a duct, in combination with a cyclone separator, including a separating cylinder and a centrally disposed exit pipe, the lower of the two plates being provided with a central hole, and being attached tightly to the exit pipe of the separating cylinder so that the hole in the plate is concentric with the exit pipe of the cylinder, the upper plate extending over and beyond the hole in the lower plate a sufllcient distance to insure diffusion.

5. A cyclone separator consisting of two vortex chambers each having a peripheral opening and placed one above the other on a common center line, the chambers communicating with each other through a central hole or pipe, with a chamber at the bottom of the lower vortex chamber for collecting or leading off separated material, and an annular chamber attached to the bottom of the upper vortex chamber for collecting or leading oiif separated material, whereby the fluid stream may flow in either direction through the separator with effective separation.

6. The combination with a cyclone separator having a cylindrical separating chamber, a tangential inlet for dust-laden air, means for collecting material separated from the air in said chamber, and a centrally disposed exit pipe for the air from said chamber, of means for reducing the velocity and increasing the pressure of the air discharged from said exit pipe comprising a lower plate connected to the end of the pipe above the top of said separating chamber and an upper plate overlying the lower plate and the pipe whereby to reduce the pressure drop in the flow path and reduce the power input.

7. The combination with a cyclone separator having a cylindrical separating chamber, a tangential inlet and a centrally disposed exit pipe, of a difiuser comprising a pair of superposed plates of substantially the same diameter as said separating chamber, the lower plate being in the form of an annulus attached to the exit pipe of said separating chamber above the top of said separating chamber.

8. The combination with a cyclone separator having a cylindrical separating chamber, a tangential inlet and a centrally disposed exit pipe, of a diffuser comprising a pair of superposed cones of substantially the same diameter as said separating chamber, the lower cone being in the form of anannulus attached to the exit pipe of said separating chamber, said cones being disposed substantially fusion.

9. The combination wlth a cyclone separator having a cylindrical separating chamber, a tangential inlet and a centrally disposed exit pipe, of a diifuser comprising a pair of superposed plates of substantially the same diameter as said separating chamber, the lower plate being in the form of an annulus attached to the exit pipe of said separating chamber, and vertical guide vanes arranged between said plates to promote diffusion.

10. The combination with a cyclone separator having a cylindrical separating chamber, a tangential inlet and a centrally disposed exit pipe, of a diil'user comprising a pair of superposed plates of substantially the same diameter as said separating chamber, the lower plate being in the form of an annulusattached to the exit pipe of said separating chamber, and a scroll connecting the peripheries of said plates and having an exit opening of approximately the same cross-sectional area as the inlet of said separating chamber.

JOSEPH H. KEENAN.

close together to'insure difcm rzcm or Wm, I Patent No. 2; 033, 7o. Q March 10; 1936 JOLSEPH a. m mz.

It is hereby certified that error appears in the printed specification 0: the above numbered patent requiring correction as follows: Page 3, first column, line 66, claim 3, for "disclosed" read disposed; and that the said Letters Patent should be read with this correction therein that thesame ma conform to the record of the case in the Patent Office.

signed and sealed this 21st day of April, A. n. 1935.

Leslie Frazer (Seal) Acting Commissioner of Patents.

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