US3060664A - Cyclone separator - Google Patents

Description

Oct. 30, 1962 J. MORAWSKI CYCLONE SEPARATOR 6 Sheets-Sheet 1 Filed Feb. 29, 1960 INVENTOR.

JU LIAN MORAWSKI ATTORNEY Oct. 30, 1962 J- MORAWSKI 3,060,554

CYCLONE SEPARATOR Filed Feb. 29, 1960 6 Sheets-Sheet 2 INVENTOR. Jim/41v Moeiwrz/ 1952 J. MORAWSKI 3,060,664

CYCLONE SEPARATOR Filed Feb. 29, 1960 6 Sheets-Sheet 3 I NV EN TOR. Juz mw MOZflM/JZ/ Oct. 30, 1962 J. MORAWSKI CYCLONE SEPARATOR 6 Sheets-Sheet 4 INVENTOR JULlAN MORAWSKI W%% I ATTORNEY Filed Feb. 29, 1960 F1 .13

Oct. 30, 1962 J. MORAWSKI CYCLONE SEPARATOR 6 Sheets-Sheet 5 Filed Feb. 29, 1960 ATTORNEY Oct. 30, 1962 J. MORAWSKI 3,060,664

CYCLONE SEPARATOR Filed Feb. 29, 1960 6 Sheets$heet 6 INVENTOR. JULIAN MORAWSKI ATTORNEY United States Patent ice.

3,060,664 CYCLONE SEPARATOR Julian Morawski, 448 35th St., Manhattan Beach, Calif. Filed Feb. 29, 1960, Ser. No. 11,760 21 Claims. (Cl. 55-431) This application is a continuation in part of my copending application, Serial No. 712,848, filed February 3, 195 8, for Cyclone Separator.

This invention pertains to a device for separating solid particles from gaseous suspension, and more particularly to separators of the centrifugal or cyclone type.

The desirability of removing solid particles from gases emitted into the atmosphere of industrial areas is well known. Damage to vegetation and buildings can be extensive, while the health of the residents may be adversely afiected. Cleaning of gases discharged into the atmosphere, therefore, has become recognized as a necessity in the present industrialized society.

One of the simplest and most economical to construct and operate of the various known separating devices is the centrifugal or cyclone type of separator, wherein the dust laden gases are rotated at high velocity thus permitting removal of the heavier solid particles by centrifugal force. However, the inability of these devices to remove particles of a very fine size, and their relatively low efficiency and lack of consistency in separation even of larger particles, has limited the use of cyclone type separators. Many efiorts have been made to improve the performance of these units, such as by conducting portions of the gas to auxiliary separating devices, or by including various baflles in the hope of altering the flow within the separator in a manner which would improve the ability of the separator to remove dust from the gas. These schemes have increased the size and complexity of the separator assemblies, yet have not materially added to their efilciency. Therefore, cyclone separators have not been utilized where top performance is required.

It has been possible to remove the greatest percentages of particulate matter by means of electrical devices which precipitate the solid particles from the gas. However, these electrical separators are extremely costly to purchase and maintain. Many of them will not operate properly on heavy dust concentrations and require additional units in the form of mechanical separators for precleaning the gas before it is sent to the electrical precipitator. Another factor adding to the size and expense of the electrical separators is their requirement for low gas velocities past the electrodes. Furthermore, these units do not operate properly at elevated temperatures which in many instances necessitates the provision of extra equipment for cooling the gases. Also, corrosive gases or liquids materially shorten the life of the electrodes and reduce their eifectiveness. Furthermore, while these electrical separators are generally efficient in their separation of most solid particles from the gases, they are somewhat less effectual for gases containing dusts with high concentrations of carbon.

Other separating devices also have inherent shortcomings. The bag type, having fabric filtering media, cannot be used for high temperature gases and requires low gas velocities. These devices are subject to considerable wear and consequently have a short life and require high maintenance expense.

Gas washers and scrubbers also are utilized in cleaning gases, but they demand a large supply of water which is not always available. Also, they require compressors, pumps, driving machinery and the like, all of which involve expense, maintenance difliculties and space requirements. Disposal of the slude produced by these separators presents a troublesome problem.

3,060,664 Patented Oct. 30, 1962 The device of this invention provides a cyclone separator having the advantages of simplicity and economy that are possible with such units. Its efliciency is far superior to the usual cyclone separator, and is on a par with that obtained by electrical separators. However, unlike electrical precipitators, its performance is not impaired when carbon particles are found in the gases, but all materials are removable regardless of their chemical composition. The temperature of the gas or its corrosiveness likewise does not limit the effectiveness of the device of this invention. These results are achieved by providing a special annular passageway around the gas outlet for the unit to receive gases highly laden with dust, which then are conducted automatically to the bottom portion of the cyclone and discharged in a rotational pattern at the location within the cyclone of highest separation efiiciency. -Preferably, the annular passageway is in the form of a diifuser to eifect maximum pressure recovery and increase the pressure gradient that causes the by-pass flow of gases to the bottom of the separator. Additional baffles may be included to deflect the solid particles in the gas to the annular passageway, and means may be provided to inject a driving fluid in a rotational path at the area below the gas outlet in order to increase the velocity rotation at that point and hence the efficiency of separation.

Accordingly, it is an object of this invention to provide an eflicient, simplified, low cost cyclone separator.

Another object of this invention is to provide a cyclone separator having means for increasing the velocity of rotation of the gases locally within the cyclone body, but requiring no moving parts.

A further object of this invention is to provide a cyclone separator which takes advantage of the natural flow phenomenon inside of the separator to remove gases having heavy dust concentrations from the area of the gas outlet, and discharge these gases in the portion of the separator of most efiicient operation and in such a manner as to increase the rotational velocity within the separator.

An additional object of this invention is .to provide a cyclone separator having provision for recirculating dust-laden gases in order to increase the probability of separation of particulate material.

Another object of this invention is to provide a separating device having provisions for adding a driving fluid for increasing the velocity of rotation of the mass within the separator.

Yet another object of this invention is to provide a separator having deflectors arranged to divert solid material away from the center of the gas outlet, and having an intercepting bypass arranged to receive material so deflected.

A still further object of this invention is to provide a separator having means for increasing the velocity of rotation locally in the vicinity of the gas outlet.

Yet another object of this invention is to provide a separator having means for bypassing particulate material, which normally would enter the gas outlet at the upper end of the housing, to the lower end of the housing for separation from the gas and entry into the hopper.

An additional object of this invention is to provide a cyclone separator having means for imparting a helical pattern of rotation in the vicinity of the inlet to reduce interference and turbulence at the inlet scroll.

Yet another object of this invention is to provide a cyclone separator which subjects the gas to only a very low pressure loss.

Still another object of this invention is to provide a cyclone separator having a lower cut size of removable particles than conventional design, and c apgble of removing a higher ercenngear particles above the cut size than'can be'accomplished by other separators.

A further object of this invention is to provide a cyclone separator capable of separating out solid or liquid particles of low density and of diameters under ten microns.

These and other objects will become apparent from the following detailed description taken in connection with the accompanying drawing in which:

FIG. 1 is a schematic illustration showing the flow pattern with a cyclone separator,

FIG. 2 is a schematic view similar to FIG. 1 depicting the tangential velocity and static pressure values found within a cyclone separator,

FIG. 3 is a schematic view similar to FIGS. 1 and 2 showing the efliciency of separation at various locations within a conventional cyclone separator,

FIG. 4 is a side elevational view of the separator of this invention,

FIG. 5 is atop plan view of the arrangement of FIG. 1,

FIG. 6 is an enlarged longitudinal sectional view taken along line 6-6 of FIG. 5,

FIG. 7 is a fragmentary side elevational view illustrating the helical wall at the entrance to the separator of this invention,

FIG. 8 is a fragmentary sectional view of the bypass discharge nozzle taken along line 8-8 of FIG. 6,

FIG. 9 is a fragmentary sectional view showing a modified form of bypass inlet arrangement,

FIG. 10 is a fragmentary view similar to FIG. 9 of a further modification of the bypass in which no difiusion takes place,

FIG. 11 is a longitudinal sectional view similar to FIG. 6 showing an arrangement in which a means for deflecting particles to the bypass and for locally increasing the velocity of rotation is included,

FIG. 12 is an enlarged sectional view taken along line 12--12 of FIG. 11 illustrating the discharge nozzles for the driving fluid used in locally accelerating the flow velocity,

FIG. 13 is a fragmentary sectional view of a further modification in which dual bypass inlets are included,

FIG. 14 is a fragmentary sectional view of a dual bypass unit which also includes an element for deflecting particles outwardly toward the bypass openings,

FIG. 15 shows a further modification of a dual bypass unit,

FIG. 16 is a fragmentary view of a modification of the arrangement of FIG. 15 to include an annular element around the central deflecting member,

FIG. 17 is an enlarged fragmentary view of an arrangement similar to FIG. 16, but including means for locally increasing the velocity of rotation at the axis of the outlet members, and

FIG. 18 is an enlarged sectional view taken along line 18-18 of FIG. 17 showing the arrangement of the manifold and the discharge nozzle for the driving fluid.

The provisions of this invention can best be understood by considering briefly the flow phenomena present in and inherent to cyclone separator devices. In a typical cyclone separator, such as shown schematically in FIGS. 1, 2 and 3, the dust laden gas enters the separator through a scroll 1 leading into the upper cylindrical portion 2 below which is a frustoconical section 3. The bottom end of the latter communicates through opening 4 with hopper 5 which is to receive the separated dust particles. An outlet tube 6 extends into the upper end of the unit and discharges the cleaned gas.

When the gas is discharged in a rotational pattern by inlet scroll 1, a vortex is produced within the housing, limited in diameter by the outer walls 2 and 3. Also, there is a downward component of velocity moving the rotating mass along the walls toward the bottom of the unit and outlet 4 (see FIG. 1). A center column of gas rises upwardly from the bottom of the unit, moving along the axis of the housing into outlet 6. Some eddies from the downwardly moving material also circulate inwardly and enter the central core of rising gas, to be drawn into outlet 6.

In addition to this overall pattern, there is present a rotating doughnutshaped ring of gas at the upper end of the housing around outlet tube 6, resulting from the geometry of the scroll inlet and the proximity of the gas outlet tube. In addition to the rotational movement of this annulus, there is local circulation about its circumferential axis. This movement is downward adjacent tube 6 and upward at the location of the outer wall 2.

The underlying principle on which all cyclone separators operate is that the particulate material, being heavier than the gas, is driven to the housing walls 2 and 3 by the centrifugal force resulting from the overall rotational pattern. There the particles are carried by the downward velocity component into outlet 4 and hopper 5.

In its relative outward motion under the influence of centrifugal force, the solid particle is also subjected to an opposing drag force exerted by the gas and tending to drag the particle through outlet 6 along with the gas. It is apparent that the centrifugal force on the smaller and the less dense particles will not be as great as the centrifugal force on the larger and heavier particles. Therefore, at some critical point in particle size, the centrifugal force will not able to overcome the drag on the particles caused by the radial currents of gas entering the central column of gas rising to outlet tube 6. Such smaller particles, therefore, cannot be separated, but will leave the unit along with the gas. This minimum size of separable particles is known as the cut of the separator.

All particles larger than this diameter should be removed from the gas stream. However, all cyclones of conventional design suffer from an inherent and objectionable characteristic in that they allow a large number of particles bigger than this limiting size to pass to the gas exhaust with the cleaned gas and hence lower the separation efliciency of the apparatus.

As a result of the flow pattern within the cyclone and the forces acting therein, the tangential velocity of the rotating mass will exhibit the characteristics indicated by curves A1, A2, A3, A4 and A5 in the schematic representation of FIG. 2. It can be seen from this illustration that throughout the housing the tangential velocity increases as the axis of the housing is approached, dropping off only at the location of the central upwardly moving core of gas. Near the bottom of the housing, where the gas becomes more constricted by the walls 3 of the housing, the tangential velocity of the gas becomes greatest. The lowest tangential veolcity is indicated in curve A1 adjacent outlet tube 6. In other words, at the latter location the radial component of velocity will be greater in proportion to the tangential velocity than elsewhere within the housing.

The static pressure within the separator is indicated by curves B1, B2, B3, B4 and B5 of FIG. 2, having a maximum value at Walls 2 and 3 and decreasing toward the axis of the housing. In addition, there is a vertical pressure gradient, with the static pressure near the bottom of the unit, where the swirl velocity is greatest, being at its minimum value, ranging to the highest static pressure near the top of the unit. Thus, in general it can be said that at the top of the housing in the vicinity of the outlet for the gas, the lowest tangential velocity is accompanied by the maximum static pressure, and at the opposite end Where the tangential velocity reaches its highest value the static pressure is at its minimum.

As a result of the phenomena discussed above, the efficiency of a cyclone separator in removing particles from the gas varies widely at different locations within the separator. This is graphically represented in FIG. 3 where a plurality of iso-efiiciency curves is plotted for different positions within the separator. It may be seen that curve C1 adjacent outlet tube 6 represents an efliciency of only 20%, While a short distance below, as represented by curve C6, the efiiciency of separation has reached almost 100%. Thus, by their nature, cyclone separators have the ability to separate most solid particles, except near the outlet for the cleaned gas. It is in this critical area that the overall efiiciency of conventional units is greatly impaired.

There are two principal reasons for the extreme reduction of efficiency as the gas outlet of the separator is approached. One is because, as discussed above and shown in curve Al, the tangential velocity component adjacent outlet tube 6 is relatively low. This means that the centrifugal force, and thus the force urging the solid particles toward the outer wall of the housing and away from the central gas outlet, is at a minimum value. Therefore, with a reduced centrifugal force urging the particles outwardly, they can be more readily swept along with the gas entering outlet tube 6.

The other and perhaps even more important factor results from the rotating annulus formed near the inlet where the gas is filled with unseparated particulate material. With the fiow pattern within this rotating ring passing upwardly along wall 2, inwardly across end wall 7 and downwardly around the outer surface of outlet tube 6, particles within this ring will be thrown against walls "2, 7 and 6 by centrifugal force. The rotation about the circumferential axis of this annulus will cause such particles to creep along these walls until the entrance to tube 6 is reached. At this point these particles will be drawn into outlet 6 by the strong upward currents entering this tube.

These two factors of the lowered tangential velocity and the centrifugal force within the rotating ring are the principal causes of the poor efiiciency in the vicinity of the gas outlet. Their result is that many particles larger than the cut size of the separator will leave the unit through the gas outlet. Thus, conventional cyclones have fallen far short of their theoretical ability to remove solid matter from the gas.

The device of this invention is designed to materially increase the efliciency at the critical area near the gas outlet, augmenting the rotational speed and precluding the entrance of dust laden gas from the rotating ring into the outlet tube. In accomplishing this, the natural static pressure gradient between the top and bottom portions of the housing is utilized in causing an automatic circulation without significant frictional losses.

With reference now to FIGS. 4 through 8, the improved separator of this invention includes a housing 10 having a relatively short upper cylindrical portion 11 connecting to the lower frustoconical section 12 as in conventional designs. An inlet scroll 13 admits the dust laden gas to the separator at the upper end of the cylindrical section, while at the bottom of the housing outlet 14- leads to a hopper 15 where the separated dust is to be deposited. In the embodiment illustrated, scroll 13 discharges in a clockwise direction as viewed in top plan.

As one of the features of this invention, inlet scroll 13 includes a lower wall 16 inclined inwardly to join the cylindrical section along a helically arranged connecting line 17 as best seen in FIGS. 4, 6 and 7. The lower end 13 of wall 16 merges into the cylindrical section at a location immediately below where the scroll discharges into the housing. This enables the inlet gas to smoothly enter the rotating mass within the housing reducing turbulence and pressure losses, and improving the flow pattern. Thus, as the gas is conducted into the housing, it is directed downwardly by wall 16 to avoid interference with the incoming gas leaving scroll 13.

In the arrangement of FIGS. 4 through 8, a frustoconical exit tube 26 extends axially downward into the top end of the housing for receiving the central core of cleaned gas and removing it from the housing. Sturounding exit tube 20 is an additional frustoconical tubular element 21,

6 the bottom edge 22 of which is below bottom edge 23 of member 20.

On the exterior of exit tube 20 is an outwardly flaring portion 24 joining a substantially cylindrical portion 25. This causes a restriction in the portion of passageway 26 between members 20 and 21 where sections 24 and 25 meet, while the upper end of this passageway is divergent in cross sectional area in view of the outwardly tapering nature of member 21.

An outlet 27 is provided for the upper end of member 21 connecting through elbow 28 to a tube 29 which extends downwardly to the lower end of the housing section 12. Tube 29 terminates in a convergent nozzle 30 inclined downwardly and arranged to discharge tangentially along the inner wall of the lower end portion of the conical section 12 of the housing, as best seen in FIG. 8. the direction of discharge of nozzle 30 is the same as that for scroll 13, being clockwise as seen from above as in FIG. 5.

Some latitude is permitted in the positioning of nozzle 3-0, but particularly satisfactory results have been obtained when it is located above outlet opening 14 a distance equal to one-half to four times the diameter of this aperture. Also, it is preferred to incline the nozzle downwardly so that angle alpha with respect to the horizontal plane of the separator, is within the range of live degrees to twenty degrees. I

Several important advantages are realized by this construction, resulting in eificiency far superior to anything previously obtainable in a separator of this type. It may be noted that the bottom end 22 of the outer tubular member 21 is located in the zone of minimum separation efiiciency of the cyclone unit. As discussed above, the central column of upwardly rising cleaned gas tends to pick up solid particles from the gas near the gas outlet where the rotational velocity is relatively slow and hence the centrifugal force on the particles is at a minimum. Further, solid particles tend to enter the outlet tube from the rotating ring within the scroll area.

However, as the particulate material within the body of the separator is drawn toward the periphery of the central core of upwardly moving gas, it will enter outer tubular member 21 and be bled ofi through the passageway 26 instead of leaving the housing through the gas outlet. Also, the particles which creep along the walls near the gas exit due to the rotating ring at the area, will move downwardly along the exterior of tube 21 to its lower end 22. There these particles will be drawn into the bleed passageway 26 instead of entering gas exit tube 20. Therefore, the annular passageway 26 between members 20 and 21 will receive virtually all of the solids in the gas, to bypass them through conduit 29 to nozzle 30. The outwardly flaring portion 24 on the exterior of tube 20, and the resulting restriction in the passageway caused thereby, tends to increase the upward velocity of the peripheral gases at this point, helping to draw the particulate matter into the annular area between the two tubular sections. Outwardly flaring portion 24 also helps to physically deflect the particles into this passageway.

As discussed above, a characteristic of a cyclone type separator is the existence of a pressure differential between the top and the bottom portion of the housing. This pressure differential is utilized in drawing the heavily dust laden gases into the passageway 26 between members 20 and 21 and conducting them downwardly into the bottom end of the housing. In view of the lower pressure at the bottom end of the housing, a natural circulation will be provided, automatically sucking the dust and gases from the annular area around tube 20 and conducting them to the bottom of the housing. Thus, no moving parts or auxiliary equipment are necessary for withdrawing the mixture of dust and gas from around the central clean core and discharging it into the lower end of the housing.

The position of nozzle 30, by being tangential to the wall at the lower end of the housing, causes the gas discharged from the nozzle to swirl in a rotating pattern. This reinforces the natural rotation of the gas within the housing and augments the tangential velocity that is obtained. Hence, the discharge from nozzlze 30 serves to increase the rotational speed of the mass within housing 10, even further raising the efficiency of separation of particulate matter from the gas. As a result, the cut of the separator is shifted to a lower range of particle size. This enables the device not only to obtain a higher degree of separation for the particles within the housing, but also to separate particles of even smaller size than would otherwise be possible. Thus, the gas with the heavy dust concentration discharged from nozzle 30 is rotated at an exceptionally high speed so that nearly all of the particulate material will be separated, driven against the walls of the housing and conducted downwardly into hopper 15.

If any residual particles remain within the gas rising from the bottom of the housing, they again may be diverted into the passageway 26 between members 20 and 21 and reconducted to the bottom of the housing for separation. There is no limit to the number of times that the patriculate material may be so circulated through the unit, and as a result, the possibilities for separation from the gases are greatly enhanced. This is especially true since during the recirculation process the very fine particles can grow in size by coagulation due to impact, electrostatic charges and the like.

The slight downward inclination of nozzle 30 assists in correcting another shortcoming of most cyclone separators. Under many conditions where heavily laden gases are to be cleaned, the dust will accumulate around the outlet from the conical portion, choking this opening and preventing any further discharge into the hopper. However, by inclining nozzle 30 downwardly, the discharge from the nozzle is blasted toward the opening 14 and always maintains this opening free of any congestion. There will be no choking of outlet 14 when the nozzle 30 is given as inclination in that direction. Therefore, for maximum efliciency it is important to discharge the bleed dust and gas both in a rotational pattern in the bottom of the housing, and toward the hopper entrance. This assists the natural flow pattern within the housing, avoiding the creation of turbulence or pressure losses, increasing the velocity of rotation and improving the ability to separate particular matter, while assuring that no choking of the dust outlet can occur.

The diverging portion of the passageway 26 between members 20 and 21, above the restriction caused by member 24, causes the passageway to act as a diffuser. This permits eflicient pressure recovery, raising the static pressure at the upper end of this passageway without undue losses. Therefore, the pressure differential between the top and bottom portions of the cyclone is increased so that there is an even greater tendency for the material around member 20 to be drawn into the annular passageway and conducted to the lower end of the housing. A head of from two to five inches of water will be maintained to cause the automatic flow through the bypass. Normally from five to twelve percent by volume of the gas will be recirculated in this manner. Although not usually required, a valve 31 may be included in line 29, if desired, to control the bypass flow.

Primarily to decrease the cost of manufacture of the unit by simplifying its construction, the upper portion of the device may be constructed as indicated in FIG. 9. This includes the provision of concentric frustoconical tubular members 32 and 33 for the gas outlet and bypass, respectively. According to this design, however, the frustoconical shape of the gas outlet member 32 is retained on both its interior and exterior surfaces. This means that there is no constriction in the bypass passageway 34, and no outwardly flaring surface at the intake portion of the gas exit member for deflecting the solid particles into the annular passageway. However, the diverging nature of the bypass 34 causes it to act as a diffuser, resulting in an efficient pressure recovery and an increased pressure differential between the top of the bleed passageway and the location of the nozzle at the bottom end of the housing. This modification, therefore, is only slightly less efficient than that of the previously described embodiment.

An even more economically constructed unit is illustrated in FIG. 10 where both the gas outlet member 37 and the outer bypass tube 38 are simple, straight-sided cylindrical members. While the device will function essentially as described before in drawing the dust laden gases from around the perimeter of the clean gas outlet, the cylindrical member 38 does not act as a diffuser. This means that there is no increase in pressure differential between the top and bottom of the unit, and also that some added pressure losses may be expected from the flow of gases through the bypass assembly. This embodiment, therefore, normally will be selected where separation requirements are less exacting and construction at a minimum cost is a primary objective.

Particularly useful for more sizable units where large volumes of gases must be handled is the arrangement illustrated in FIGS. 11 and 12. In such separators the tangential velocity of the vortex at the entry to the cyclone usually is relatively low, being less than the linear velocity of the inlet duct. Because of this and to avoid excessive pressure losses, the ratio of the housing diameter to the diameter of the outlet tube must be kept relatively small. Therefore, angular velocities in the vicinity of the gas outlet, and consequently the centrifugal force acting on the solid particles, do not reach a high value. Even with provision for external means to accelerate the angular momentum of the entire mass within the separator, with consequent large expenditure of energy, adequate velocities often are unattainable in conventional designs.

These problems of large separators are overcome by the provisions shown in FIGS. 11 and 12, where the annular bypass provided around the gas outlet may be constructed generally as in any of the previously described designs. Typically this includes a frustoconical exit member 39 for the gas at the axis of the housing, surrounded by a larger frustoconical tube 40 to define an annular passageway 41 for connection with bypass line 29. Lo-

- cated generally beneath these members, within cylindrical extension 42 depending from member 40, but in the upper portion of the housing, is an additional unit 43 which performs two functions in further augmenting the efliciency of separation. First, this unit includes a depending conical end 44 at the axis of the housing which presents a surface which acts as a deflector to direct any particulate material remaining in the gases outwardly toward the inlet to the annular passageway 41 between members 39 and 40. Any solid particles which contact the surface of portion 44 will be forced outwardly and virtually to the radial position of the inlet to this annular passageway so that the natural tendency will be for such particles to enter the bypass to be conducted into the downwardly extending tube 29.

In addition, a provision is made to discharge a driving fluid into the housing at the location of member 43 for increasing the rotational velocity at that location. As discussed above, this member is positioned generally in the area of the housing where tangential velocity components are at a minimum so that centrifugal force and separating elficiencies become quite low. This driving fluid, which may be steam, air or any desired gas, enters the housing through tube 45, being discharged in through the upper portion 46 of member 43, and from thence outwardly through a plurality of circumferentially arranged nozzles 47. As best seen in FIG.12, these nozzles are positioned to direct the fluid received from tube 45 in a rotational pattern in the same direction as obtained by the natural flow within the separator. The gas emanating from these nozzles, impinging upon the material within the housing,

locally speeds up the flow and materially increases the tangential velocity at the upper axial portion of the housing. Therefore, the centrifugal force acting upon the particulate material at this critical area of the device is substantially raised and a much higher degree of separation is obtained. It is unnecessary in accomplishing this to accelerate the flow of entire mass in the cyclone. Therefore, the auxiliary member 43 acts both to deflect the particulate material outwardly toward the annular passage and to increase the velocity of rotation of the gases near the gas outlet so that the efficiency of the unit is enhanced. Again, the construction is relatively simple necessitating no moving parts within the separator, and only the discharge of relatively small quantities of driving fluid through the nozzles 47. Frequently, in industrial installations, there is suflicient Waste heat to produce enough steam to adequately supply the jets 47, so that the supply of driving fluid is obtained without added operational expense. Where gas temperatures or corrosiveness might preclude the use of external blowers or exhausters, no limitations are imposed when local acceleration is induced by the driving fluid.

In many installations, particularly for larger sizes of cyclones, it is advisable to provide a double passageway for dust laden gas around the exit tube where the clean gas leaves the housing. An arrangement of this type may be seen, for example, in FIG. 13 where gas outlet tube 50 is located within a second concentric tubular member 51 which includes a straight cylindrical section 52 well below the entrance to gas outlet 50. The upper end of member 51 is in the form of an outwardly flaring frustoconical element 53 around the gas exit tube to form a bleed passageway 54. As discussed above, the diverging nature of passageway 54 causes it to act as a difluser increasing the pressure at the upper end 56 of the bypass.

Depending portion 52 of member 51, being located at the axis of the housing, receives the central column of gas rising from the bottom of the unit. The particulate matter that may have become entrained with this core of gas will be near its periphery. Therefore, at the entrance to passage 54 the particles will simply enter passage 54 to be conducted to the bottom of the unit, rather than entering gas outlet 50.

In addition, this version of the invention is provided with a second tubular element 57 around member 51, resulting in a second annular passageway 58 opening into the upper end 56 of the bypass passage. Diverging sec tion 59 enables the second annular passageway also to act as a diffuser for realizing eflicient pressure recovery.

The annular passageway 53 receives heavily dust laden gas from the rotating vortex ring at the inlet to the housing before any of the particles have had an opportunity to enter the current of gas passing into outlet 50. Thus immediately upon entering the housing, a portion of the gas at the upper end and along the wall of the housing, where the heaviest concentration of dust is encountered, is drawn off into the passageway 58 between members 57 and 51 to be conducted to the lower end of the housing where the efliciency of separation is at its greatest. Therefore, by having dual entrances, the bypass receives not only particulate material that has circulated through the housing and failed to separate from the gas, but also draws in solid particles close to the inlet to the cyclone.

Where the axial lengths of passageways 54 and 58 are considerable, it is preferred to include a plurality of openings 60 in the upper wall portion 53 of member 51. This provides for pressure equalization between the two annular bypass passage-ways prior to their entrance into the main bypass conduit. This is desirable to avoid eddy currents and consequent turbulence and pressure losses from gases entering the bypass at different pressures.

According to the version of FIG. 14, dual bypass openings again are provided by the main gas outlet 62, frustoconical member 63, and a second tubular member 64 around the exterior. In addition, a central deflecting member 65 is supported at the axis of the tubular members having its downwardly convergent portion 66 beneath the entrance to tube 62, while its upwardly convergent portion 67 extends the length of member 62. This member 65 acts generally in the manner of member 43- described above for the embodiment of FIG. 11, assisting to deflect the solid particles into the annular passageway 68 provided between members 62 and 63. Particles deflected by lower portion 66 have only a short radial distance to move in entering the bypass 68. The upper portion 67 of member 65 also allows a gradual pressure recovery of the gases in the outlet tube 62 so as to permit improved flow through the gas outlet from the separator.

The arrangement of FIG. 15 is somewhat similar to that of FIG. 14 except that the tubular member 69 around gas outlet 76 includes a lower divergent-convergent portion 71 in which is supported an axially disposed deflector 72, similar in contour to member 65. Therefore, solid particles are deflected to the wall of element 71 to be transmitted into the bypass 73. The relatively wide maximum diameter of member 71 assists in permitting virtually all of the particles to reach a radial position at least as far from the axis as the mouth of passageway 73. Improved pressure recovery is obtained not only in a gas outlet of the device, but also in the bypass system by reason of the positioning of member 72 in the lower portion 71 of the downwardly extending annular member 69. Again, an outer tubular section 74 is included to provide the second annular bypass 75 for the rotating vortex within the entrance portion of the separator.

Much like the design of FIG. 15 is the construction of FIG. 16 where an added cylindrical section 76 has been included. This provides with member 72 a divergent passageway 77 for eflicient diffusion and pressure recovery. The outwardly flaring surface 78 of member 76 adds an additional deflector for directing particulate material outwardly to the wall of member 71. Dilfusion and pressure recovery are accomplished in the divergent passageway between the upper portion of member 76 and the inner wall of member 71.

Provision for injecting a driving fluid for accelerating the gases at the location of the bypass and clean gas outlet is added to the previously described system in the arrangement of FIGS. 17 and 18. As shown therein, the lower portion 80 of axially disposed member 81 is recessed at 82 to accommodate a plurality of convergent nozzles 83. These are arranged to discharge in a rotational pattern having the same direction of spin as the mass of dust and gas within the separator. In addition, they are inclined upwardly from the horizontal at an angle beta of around 30. As seen in FIG. 18, they also are inclined outwardly with respect to the tangent of the circumference on which they are located at an angle gamma in the order of five to fifteen degrees.

The fluid for nozzles 83 is supplied from tube 84 which enters the housing through gas exit tube 70 and extends downwardly along the axis to the upper portion of member 81. The tube 84 passes through member 81, and suitably connects to an outwardly radiating manifold 85 which provides the driving fluid to the various nozzles 83.

When the driving fluid is ejected in a rotational pattern from nozzles 83, it entrains a portion of the main gas flow entering member 69- and, being confined initially by the baflle 76, provides this gas with a sizable increase in angular velocity. Also, by virtue of the upper inclination of these nozzles, the gas so contacted receives an additional vertical velocity component. The presence of member 76 assures that there is no interference with the main gas flow passing on the exterior of that member through member 69. The driving fluid, and the entrained gas therewith, merge with the remainder of the gas within member 69 above baflie 76, adding to the angular momentum, pressure and upward velocity of the main body of gas in the outlet. 69.

The efiect of this, first of all, is to augment the etficiency of separation by spinning the gases at a more rapid rate in the vicinity of the gas outlet to increase the centrifugal force on the particulate material, forcing it into the annular bypass opening. Also, the driving fluid assists in moving the gases through the cyclone separator and eliminates the need for external blowers or exhaust fans for pumping the gas. This movement of the main body of the gas is enhanced by the fact that the fluid injectors are inclined upwardly to give the rising gas a boost toward the exit tube. At the same time, tubular element 76 assures that no undue turbulence will be created by the discharge of the driving fluid. The provision for the driving fluid is particularly important where high temperatures or corrosive gases are encountered and it is not feasible to use external pumping means.

It can be seen from the foregoing that I have provided an improved cyclone separator which takes advantage of the natural flow pattern within the cyclone to increase its efficiency of separation, reduce the pressure losses and assist in pumping the gases to the clean gas outlet. No moving parts are required, and the movement within the separator takes place automatically. The improvements of this invention are centered around the area of lowest natural efficiency where the gases leave the housing.

The foregoing detailed description is to be clearly understood as given by way of illustration and example only, the spirit and scope of this invention being limited solely by the appended claims.

I claim:

1. A device for separating particulate material from a gas comprising a chamber having a first end portion provided with outlet means for discharging gas therefrom, a second end portion tapering inwardly from said first end portion and having an opening for connection to a hopper for receiving particulate material, an opening into said chamber at said first end for discharging gas therein in a rotational pattern, and a bypass between said ends of said chamber, said bypass having an inlet adjacent and radially outward of said outlet at said first end of said housing, and an outlet in the second end of said housing for discharging bypassed material in a rotational pattern in said second end portion and arranged to discharge in the same direction of rotation as the discharge from said inlet into said chamber, said outlet in the second end eing adjacent said opening in said second end.

2. A device for separating particulate material from a gas comprising a. chamber having a first end, an inlet for heterogeneous material at said first end for discharging into said chamber in a rotational pattern in one direction, an outlet tube at said first end extending axially therein, said chamber having an inwardly tapering open second end provided with an opening adapted for connection to a receptacle for particulate material, means surrounding said outlet in said first end defining an annular passageway, a nozzle at said second end adjacent said opening in said second end and arranged to discharge substantially tangentially in the direction of rotation of said inlet to said chamber, and a conduit interconnecting said annular passageway and said nozzle for conducting material from the region radially outward of said outlet in said first end to said nozzle for rotation within said chamber at said second end.

3. A device as recited in claim 2 in which said means defining an annular passageway includes difiuser portions for increasing the static pressure of gas received therein, said difiuser portions including a passageway of divergent cross sectional area.

4. A device as recited in claim 2 in which said inlet to said chamber includes a scroll having a bottom wall intersecting the exterior wall of said housing along a substantially helical line inclined toward said second end of said chamber.

5. A device as recited in claim 2 in which said outlet tube at said first end of said chamber isdivergent out- 12 Wardly from said chamber and includes an outer surface adjacent the inlet thereto that is inclined outwardly from the inner wall of said tube away from said entrance.

6. A device as recited in claim 2 including in addition means for discharging additional fluid in a rotational pattern similar to the rotational patterns from said inlet and said nozzle, and at a location adjacent the axis of said chamber and the entrance to said outlet tube.

7. A device as recited in claim 2 including in addition an axially disposed deflector in said chamber for deflecting particulate material toward said annular passageway.

8. A device as recited in claim 2 including in addition a second annular passageway circumscribing said first mentioned annular passageway and communicating with said conduit.

9. A device as recited in claim 2 in which said nozzle is inclined toward said opening at said second end.

10. A device as recited in claim 9 in which the angle of inclination of said nozzle, with respect to the axis of said chamber is within the range of from about 70 to about 11. A device for separating particulate material from a gas comprising a chamber having a first end, an inlet means at said first end for discharging into said chamber in a helical pattern, an outlet for said chamber at said first end, said chamber having an inwardly tapering open second end opposite from said first end and provided with an opening for receiving separated particulate material, and means for increasing the velocity of rotation within said chamber, said means including a bypass having an annular diffuser having an opening around said outlet at said first end and a divergent passageway beyond said opening, and a means for conducting material from said opening to said opposite end of said housing adjacent said opening in said opposite end for discharge therein tangentially and toward said opening in said opposite end.

12. A device for separating particulate material from a gas comprising a chamber having a first end, an inlet scroll at said first end for discharging within said chamber in a rotational pattern, a gas outlet tube at said first end extending axially into said chamber, said chamber tapering inwardly toward a second end portion opposite from said first end, said second end portion being provided with an opening adapted for connection to a receptacle for particulate material, a second tube at said first end circumscribing said first tube for defining therewith an annular passageway, a conduit connected to said passageway and including a nozzle discharging in said second end portion of said housing in a rotational pattern, and means adjacent said tubes for introducing a driving fluid into said chamber in a rotational pattern for locally increasing the velocity of rotation in the vicinity of said tubes.

13. A device as recited in claim 12 in which said annular passageway defines a diffuser for increasing the static pressure of gas received therein.

14. A device as recited in claim 12 including, in addition, a third tube circumscribing said second tube for defining a second annular passageway therewith, said second annular passageway communicating with said conduit.

15. A device as recited in claim 14 in which each of said annular passageways defines a diffuser for increasing the static pressure of gas received therein.

16. A device as recited in claim 14 in which said second tube is provided with a plurality of apertures through the wall thereof adjacent the connection thereof to said conduit for thereby providing means for communication between said annular passageways for equalizing the pressures therein.

17. A device as recited in claim 14 in which said second tube extends into said chamber beyond the entrance to said first tube, an axially disposed member and a battle being located inwardly of said first tube and substantially within said second tube.

18. A device as recited in claim 12 in which said means for introducing a driving fluid into said chamber includes a member axially disposed with respect to said tubes and having an upwardly converging upper portion and a downwardly converging lower portion, said lower portion having a recess therein and being provided with a plurality of nozzles in said recess, said nozzles being arranged to discharge rotationally about the axis of said member and inclined upwardly toward the upper end of said chamber.

19. A device as recited in claim 18 including, in addition, a baflie circumscribing said axially disposed member at the location of said recess and said nozzles, said baflie being frustoconical in form and having an outwardly flaring lower edge portion.

20. A device as recited in claim 14 in which said second tube includes a section divergent toward said first end of said chamber from a location within said chamber, and includes an additional and adjacent section convergent toward said one end of said chamber.

21. A device for separating particulate material from a gas comprising a chamber of substantially circular cross section,

said chamber having a first end,

an inlet means at said first end for discharge of a mixture of gas and particulate material in a helical pattern,

an outlet tube extending axially into said first end,

said chamber having an inwardly tapering second end opposite from said first end,

said second end terminating in an opening for receiving separated particulate material, and means for increasing the velocity of rotation within said chamber,

said means including an annular difiuser circumscribing said outlet tube,

said annular diffuser having an inlet opening and a passageway of divergent cross sectional area extending therefrom,

14 a bypass passageway connected to said diffuser for receiving material collected therein,

said bypass passageway extending exteriorly of said chamber to said second end, said bypass passageway having an outlet at said second end adjacent said opening in said second end, said outlet discharging in a rotational pattern about the periphery of an open portion of said chamber, and being inclined at an acute angle with respect to the axis of said chamber for directing the discharge therefrom toward said opening in said second end.

References Cited in the file of this patent UNITED STATES PATENTS 604,871 Allington May 31, 1898 1,231,371 Jones June 26, 1917 1,235,174 Williams July 31, 1917 1,265,763 Fender May 14, 1918 1,267,715 Tutweiler May *28, 1918 1,281,238 Wegner Oct. 8, 1918 1,288,126 Muller Dec. 17, 1918 1,581,462 McSweeney Apr. 20, 1926 1,753,502 Clark Apr. 8, 1930 1,990,943 Home et al Feb. 12, 1935 2,039,115 Rief Apr. 28, 1936 2,152,114 Van Tongeren Mar. 28, 1939 2,153,026 Ringius Apr. 4, 1939 2,414,641 French Jan. 21, 1947 2,482,362 Park Sept. 20, 1949 2,857,980 Van Rossum Oct. 28, 1958 FOREIGN PATENTS 2,818 Great Britain Feb. 21, 1890 236,371 Germany July 4, 1911

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