US2013644A - Separator system - Google Patents

Description

H. H. BUBAR SEPARATOR SYSTEM Sept. 10; 1935.

Original Filed Jan. 13, 1950 4 Sheets-Sheet 1 FIG.1

ATTORNEY Sept. 10, 1935. H. H. BUBAR 2,013,644

SEPARATOR SYSTEM Original Filed Jan. 13, 1950 4 Sheets-Sheet 3 FIG. 3' BY7NvENToyfiaAL id ATTORN EY Sept. 10, 1935. B R 2,013,644

SEPARATOR SYSTEM Original Filed Jan. 13, 1930 4 Sheets-Sheet 4 hr ATTORNEY Patented Sept. 10, 1935 UNITED STATES PATENT omen Renewed July 30, 1934.

18 Claims.

My present invention relates to separator systems of the type disclosed in my co-pending application Serial No. 70,386, filed November 20, 1925, now Patent #1,855,381 of Apr. 26, 1932 this application beiim a continuation in part of, and an improvement on, said co-pending application.

In the field of the industrial arts, a problem of ever increasing importance is that 01' separating matter, usually in the form of dust, from gases emitted by chimneys or released by refining or other manufacturing processes. The existence of this problem may be said to be due to two major reasons; first, the pollution or contamination of the air in a community or of the air in an agricultural district; and second, to uneconomic conditions where valuable materials are allowed to escape-and are thereby wasted.

It is well established that in the administration of a community or district, rigid measures may be prescribed and enforced as to the content or character of the gases which may be released by a plant. Such restrictive measures grow and become more exactly with the ever increasing size of industrial plants, increase of population in communities, and with the growth of activity in agricultural sections.

In the art concerned, the more strict repressive measures and greater potential values in waste materials have, in a large measure, been In Canada June 17,

responsible for establishing that the majority of the former processes are inadequate to cope with existing conditions and that in attempting to apply other methods the results have been disappointing or the costs have been prohibitive.

The matter which forms the dust content of laden gases may range in character from relatively heavy particles of appreciable size to particles of microscopic size and inappreciable weight. In the art, these particles are referred to in general terms as heavies and flnes", respectively. Ordinarily, least dimculty is had in separating and removing the heavy particles. Heretofore, however, the handling of the finer particles has been a perplexing problem, the difliculties increasing rapidly with the .degree of refinement or percentage of dust sought to be removed.

A phenomenon frequently encountered, particularly when dealing with gases at high temperatures, is that the dust content exhibits socalled live characteristics. In this condition the dust shows little tendency to settle, and under but slight movement of the suspending gases may continue to float for long periods. In

' many cases, particularly in high temperature gases, each dust particle becomes enveloped in a gas film which greatly increases its surface tension and adds to its buoyancy. This is particularly noticeable in coal particles at fairly high temperatures, and is the reason why coal dust is so hard to catch. Every particle with its own gas envelope may be compared to a rubber ball, the gas envelope blocking adherence to other particles or adhesion to collecting elements.

Moreover, conducting particles may become (11- 10 rectly charged due to an ionized condition of the gases, and some of the ions may also attach to'the non-conducting particles. In such a state the different particles are charged in a like polarity sense, and due to mutual repulsion, show' substantially no tendency to coalesce and settle, with the result that a large percentage of the finer particles are carried through the ordinary separator apparatus. The importance attaching to removal of the finer dust particles is usually greater than that resting with removal of the heavier dusts, principally due to the fact that the former may drift or float to greater distances before settling and thus menace or pollute larger areas. Thus, dust passing through a 300 mesh but retained on a 325 mesh has an approximate diameter of microns. This dust, discharged from a stack 200 it. high, with a wind velocity of ten miles per hour, would probably be precipitated within a maximum radius of iii- 30 teen miles. 'Dusts finer than this would be carried greater distances with the result that the average dust particle of 10 micron diameter or less, would be carried so far and become so diffused as to be impossible to detect.

It is the principal object of my invention to provide an improved method and apparatus for more effectively, reliably, and economically separating and recovering solid matter from gases, including gases at high temperature.

Prior systems and proposals have usually been based on such principles as filtration, centrifugation, gravity precipitation in the still areas of large settling chambers, impingement, absorption by means of liquid sprays, and electrical precipitation. Knowledge of these principles coupled with an understanding of the difiiculties peculiar to handling the finer dusts, led me to experiments looking to the introduction of a new principle in the separator art. This new principle is based on the phenomena of the free spiral vortex; observed in nature and commonly referred to as the atmospheric vortex or whirlwind.

These effects are usually due to unequal pressure areas, andin nature appear as verticalcolumns in which the spiral progression of the gyrating air is along a central axis which may have appreciable longitudinal length in transmitting air from a high pressure area at the surface of the ground to a low pressure area at some upper point.- Rarefaction at the axis is generated by the rapidity of the vorticose movement. This results in a strong inflowing current of air at the base which is drawn along and may ascend through the central axisof the column, until dispersed at an upper level. Visual evidence of a whirlwind is due to the fact that the incurving air currents at the base are charged with fine dust particles which ascend with the air as it is drawn upwards through the center of the vortex. When the dust content is sufiiciently. dense or the "loading (grains of dust per cubic foot of air) is relatively heavy an atmospheric vortex may have the appearance of a dust or sand pillar.

The phenomena of vortices differ in important ways from the phenomena of centrifugal action and ordinary eddies, when considering such principles from the standpoint of dust separation. In a free spiral vortex the higher velocities are toward the center rather than at the periphery, whereas the tangential effects are at a maximum under the centrifugal action of a free circular vortex. Therefore, while centrifugation tends to separate heavier particles of dust from gases, the inappreciable weight of fine dust particles render them immune to such action and such particles may continue in suspension in the gases unless the radius of the action is greatly reduced as compared to the velocity, since the efliciency of centrifugal action with a fixed velocity is greatly increased as the radius is reduced. Substantially similar results are had when the principles of impingement are employed, the heavier particles being susceptible to separation from the gases, following impact, while the lighter particles may be unaffected and continue in suspension.

One object of my invention is to utilize the vortex principle to effectively separate both heavy and light solid matter from gases.

Prior methods and apparatus have also utilized the principle of continued removal of solid matter from gases by a series of baffles, deflections, and the like. I have found that better results can be obtained by first concentrating the dust in a part of a flowing stream of matter laden gases, and then directing this highly dust loaded part of the stream into suitable traps and cleaners, whereby the dust is removed and the cleaned gas is returned to the main stream. This action is repeated as many times as is necessary to cleanse the gas to the required degree.

The directing of the concentrated portion of the gas fiow into the traps is obtained by providing local high and low pressure areas, the passage of the gases into the traps and cleaners and back into the main stream thus forming local flow. circuits in the main stream each of which contains a definite percentage of the total flow.

Another object of my invention is therefore to effectively and successively clean definite percentages of a flow of impurity-laden gas, every portion of the gas flow being positively subjected to the cleaning operation.

Prior installations have also utilized a plurality of difierent separating principles, such as combinations of impingement and electrical precipitation and the like. I have found it advantageous to subject a flow of impurity-laden gas to different separating principles, in order to concentrate the loading in selected portions of the gas flow and to decrease the loading in other portions; and an additional object of my invention is to subject the impurity-laden gas to both centrifugal and centripetal action for concentration, and to precipitation, filtration, and adhesion for separation, of the impurities. 4

With these and other objects in view,'the invention consists of a novel method and apparatus more fully disclosed in the detailed-description following, and more particularly set forth in the appended claims.

In the drawings:

Fig. 1 is a plan view of the separator chamber with the top removed to show the arrangement of the internal equipment;

Fig. 2 is a front elevation on the line 22 of Figure 1, the parts being cut away in different planes to show the spacing and relative arrangement thereof;

Fig. 3 is a side elevation, partly in section, on the line 3-3 of Figure 1, parts being cut away in different planes; and

Fig. 4 is a diagrammatic plan view of a portion of the separator, showing the movement of the air streams.

In order to fully carry out the principles and the objects of my invention, I have devised a separator having an upper chamber and a lower dust receiving chamber, and I have provided interception members and traps in these chambers arranged so that the momentum of the flowing gases will set up free spiral vortices leading the flowing gases and the impurities therein from the upper to the lower chamber. I have also provided diffuser elements in the lower chamber which check the gyrating movement of the gases, and deflector elements which deflect the flowing gases to low pressure areas where they may rise to again enter and form part of the gas flow,.

and I have arranged the interceptor members in the upper chamber to permit free passage of the flowing gases therebetween with sharp angular directional change, whereby solid matter therein is deflected by centrifugal action to concentrate the impurities in the gas flowing towards the formed free spiral vortices; and the following is adetailed description of a specific method and a specific apparatus which embodies the principles of my invention.

Referring to the drawings, the flow chamber it, Figure 1, is horizontally positioned in a lateral or transverse section of a draft, flue way or the like. Dust laden gases enter the inlet port I! and the cleaned and dust-free gases leave through the outlet port l2.

The flow chamber Ill has a plurality of similar rows l3, each comprising variously shaped vertically positioned members forming a series of transverse alignments across the chamber. The form and arrangement of the members forming the rows is preferably similar in each row, but may be changed to meet the specific requirements of individual installations. Each row has a plurality of receptor trap members It generally U-shapein section, combined deflector and rarefaction members 15 generally V-shape in section, and intermediate deflector and rarefaetion members l6 generally V-shape in section which are fixed in position between the members It and 15, free gap spaces I! being provided between the members l5 and the adjacent members l6, and between the members l6. Each receptor trap member M is channel shape and closed at the top, preferably by a-common closure wall as indicated in Fig. 3, and is provided with a central partition I8 and spaced deflector fins I9, 20, on each side thereof.

Referring now to Figure 3, the members I4, I5, I6, the partition I8, and the deflectorplates I930, all extend downwardly into the dust hopper 2I, partitions 22 being positioned transversely across the dust hopper in the rear of each row I3 to divide the dust hopper into a plurality of separate dust receiving compartments 23, each connected to the usual dust c itlet in any suitable manner. The partitions 22 extend upwardly to the floor line of the flow compartment, the sections 24, from the members I5 to the receptor traps I4, and the sections 25; between the receptor traps I4, being floored over, the spaces in the members I4, I5 and IB and between the sections 24, as indicated in Figure 1 affording free communication between the flow chamber and the dust receiving compartments, for the purpose hereinafter described.

A plurality of transverse bafiles 26 dependdownwardly from the floor line,-adjacent the apices of.

' the members I6, and a plurality of transverse baflie plates 21 are secured thereto, either in staggered relation, as shown at the left in Figure 3, or in similar relation, as shown at the right in this figure. A short transverse baflle 28 is also positioned beneath the receptor traps I I, and baifle plates 29, arranged as shown either at the left or the right in Figure 3, cooperate therewith. These baffles and baflie plates are perforated, as shown in Figure 2 at 30, for the purpose hereinafter described; the number of baffles 21 and 29 placed at each point is dependent upon the character of the dust and the velocity of the gas. In some cases it has been found necessary to use as many as four spaced on 2 inch centers one above the other.

The gases entering the receptor traps therefore have a concentrated dust content; as the gases enter, the pressure in the traps increases, since the traps are enclosed on three sides and the top, to a total pressure substantially the sum of the static and the velocity head. This increased pressure finds relief only at the bottom of the trap, with the result that the gases flow downward. As the gases flow into the traps, and pass around the ends of the fins I9, 20 on the central partition, a whirl is formed behind each fin.

The increased pressure in the trap causes the remainder of the gases to flow out through spaces II, this flow creating an aspiration effect behind member I5, since the pressure at this point is substantially the difference between the static pressure and the velocity head.

The combination of the increased pressure in the trapsand the decreased pressure adjacent the members I5 causes a strong flow of gasesdown through the traps, forward in the dust receiving compartments 23, and up through the low pressure areas behind members I5 and I6,

the pressure differential being sufiicient to produce a downward lineal velocity in the specific type of separator illustrated of approximately three times the velocity of the gases through the flow .compartment. This pressure differential, in

deflector members towards the receptor traps I4,

a considerable percentage of the gases entering the traps and impinging against the fins and -walls thereof, the remainder passing through the gap spaces H on each side in a double reverse curve to sweep on towards the second row I3. The total area of the spaces J1 and, the traps for each unit is equivalent to the free flow area between the members I5, except in the first row, the flowing gases. thus being diverted without change in velocity, and thus maintaining a uniform flow at lower power consumption and with a lower pressure drop through the apparatus.

As the flowing gases pass through the spaces II, a reversal on approximately a 150 radius occurs, thus projecting a considerable portion of the dust particles out of the reversing gases and into the path of the gases entering the receptor traps by the use of centrifugal action on a very short radius. In addition, a percentage of the dust particles are also projected, when the gases again turn, into the spaces adjacent the apices of the members I6, where the air is comparativelystagnant, thus permitting fall of the dust into the dust receiving compartments below.

While the lineal downward velocity is increased approximately three times, the spiral velocity resulting from the whirling condition established is many times the lineal downward velocity, thus creating a strong suction and a concentration of the dust content of the gases at the axial center of the vortices, which flow into the dustreceiving compartments. These vortices, if unchecked, would create suflicient disturbance to sweep the dust back into the flow chamber, and are therefore broken up by the perforated baflle plates 29, which act as diffusers. The vortices being thus broken, the gases diffuse through and over the bafile plates, carrying the dust into the dust receiving compartments to settle therein.

The relatively wide area of the low pressure triangle permits the cleaned gases to slowly rise and rejoin the main flow stream. While the gas velocity in the settling chambers is comparatively low, a considerable portion of very fine dust still floats in the rising gases. The perforated bafile plates 21 act as dust filters to further clean the gases, the finer dust adhering to the bafiie plates, and, whenever necessary, being periodically dislodged by mechanical vibration in the form of large flakes which settle to the bottom.

My improved separator therefore functions to localize and concentrate the loading in selected portions of the flowing gases, to clean these selected portions, and to return the cleaned portions to the flowing stream which is again treated in the same manner, the local high and low pressure areas inducing a series of local flow circuits for fractional cleaning of the flowing gases. The actual separation of the dust is accomplished by centrifugal separation which removes some dust from the gases passing through the spaces I! to concentrate the dust in the gases flowing into the receptor traps and to project other dust into the relatively stagnant spaces at the apices of the V-shaped members I6, by an impingement of the dust laden gases on the walls and fins of the re ceptor trap, by a free spiral vortical concentration of the dust behind fins I9, 20, by a breaking up of the vortices and a settling of the dust, and by a final filtration of the gases rising to join the main flow stream, this separation being serially repeated.

This separation results in a thorough cleaning of the flowing gases. Thus, an average screen analysis of cinder-laden exhaust gases in stoker fired boiler plants shows a dust contentof 55% retained on a 100 mesh screen, 20% retained ona 200 mesh screen, 12% retained on a 300 mesh screen and 13% passing through a 300 mesh screen. Six rows of elements of-my improved separator remove 95% ofthe total .dust in the gases,'thus trapping practically all of the dust retained on a 300 mesh screen and a large part of the still finer dust.

The fly ash in boiler plants using pulverized coal has an average screen analysis of 87% through a 300 mesh screen. Six rows of my separator elements will trap 80% of this dust. Cement dust has an average screen analysis, pf 90% through a 200 mesh screen; six rows of'elements will trap approximately 93% of this dust. The

dust obtained from the granulators in sugar refineries approximates 58% retained on a 100 mesh screen, with 12% passing through a 300 mesh screen; six rows of elements will trap approximately 98% of this dust. Gypsum dust originating from kettles and calciners averages'93% through a 3Q0'mesh screen; six rows of elements will trap..-approximately 95% of this dust. On rocladiyer dust which averages 94% through a l 300 mesh screen, six rows of elements remove approximately 93% of the total dust content.

In situations where the gases may have 9. moisture content, and particularly where the saturation point, commonly referred to in the art as the dew point", is approached, or where the dust may have adhesive tendencies, a building up or encrustation may take place on the surface of the impingement members. To meet a condition of this nature, resort may be had to means for producing mechanical shock or vibration of the members, for the purpose of dislodging such deposits. Apparatus for accomplishing this work is well-known in the art, and when required, may

be applied to the members It to l8, in a variety of ways.

In cases where the dew point may be reached, and precipitation of moisture would occur, the walls of the chamber and hopper may be jacketed for circulating a heating medium or by mixing hot dry gas with the dust laden gas or both so that the temperature of the dust laden gases may be kept well abovethe dew point. Arrangements for applying and utilizing heat in this manner are well-known in the art and therefore have notbeen shown.

In situations where it may be desired to handle gases at temperatures above those to which iron or steel may successfully be subjected, I contemplate making the members and parts from heat resistant materials or metals, such, for instance, as Calite. Usually steel may be expected to fail entirely or to have a short life at temperatures higher than 900 degrees Fahrenheit Therefore in order to realize an operative separator for use in situations where the temperatures may be of the order mentioned, it is only necessary to substitute a suitable heat resistant material for ordinary metals in fabricating the separator equipment of my present invention.

My novel separator is therefore efficient in operation, requires practically no attention or supervision, and is economical to construct and to maintain in operation. The specific arrangement of deflector members results in a large increase in the nozzle area, thus reducing the size 70% of the total cross-sectional area of the separator; the new separator construction therefore occupies much less space than separators of other designs, and operates with a slightly higher effl ciency and a considerably lower pressure drop 5 across the apparatus. In addition, the simplicity of construction permits fabricationat a substantial decrease in initial first cost and in upkeep and maintenance; the construction also facilitates the addition of new units whenever required 1 to meet increased duty.

While I have described a specific operation and a construction, it isobvious that desired changes in operation, in structure and in arrangement, may be made within the spirit and scope of the 15 invention as defined in the appended claims.

I claim: I

1. In an apparatus for separating dust fromv gases, a gas flow chamber having a gas inlet and a gas outlet, means for repeatedly separating a portion of the main gas flow therefrom, means for cleaningthe separated portion, and means for returning the cleaned portion to the main gas flow prior to the succeeding separation.

2. In an apparatus for separating dust from gases, a gas flow chamber, a dust collecting cham-, ber, traps in said fiow chamber leading to said dust collecting chamber, and deflector members converging towards each trap for directing the gases thereinto.

3. In an apparatus for separating dust from gases, a gas flow chamber, a dust collecting chamber, traps in said flow chamber leading to said dust collecting chamberfor separating and directing a portion of the main gas flow thereto, defiector members for directing the gases into said traps, said deflector members creating high and low pressure areas in said flow chamber, and conduits for returning the gases from said dust collecting chamber to said low pressure areas. 4

4. In an apparatus for separating dust from gases, a gas flow chamber, a dust collecting chamber, spaced traps in said flow chamber leading to said dust collecting chamber for separating and directing a portion of the main gas flow thereto, spaced deflector members for directing the gases into said traps and between said traps, said deflector members creating high and low pressure areas in said flow chamber, and conduits for returning the gases from said dust collecting chamber to said low pressure areas.

5. In an apparatus for separating dust from gases, a gas flow chamber, a dust collecting chamber, traps in said fiow'chambcr leading to said dust collecting chamber, whirl imparting means in said traps, and deflector members for directing the gases into said traps.

6. In an apparatus for separating dust from gases, a gas flow chamber, a series of independent dust collecting chambers positioned succes- 50 sively in the direction of flow, conduits leading from said gas flow chamber to said dust collecting chambers, and conduits leading from each dust collecting chamber to said gas flow chamber whereby a series of successive local flow circuits 5 for the gases are established.

'7. In an apparatus for separating dust from gases, a gas flow chamber, a series of spaced traps, and a series of spaced deflector bailies converging towards said traps, whereby the gas stream is divided into one portion entering the traps and another portion passing through the bailie spaces and between the traps, said baflles being positioned to produce a reverse flow in the gases passing through the bafile spaces.

8. In an apparatus for separating dust from gases, a gas flow chamber, a series of spaced traps, and a series of spaced deflector bafiies converging towards said traps, whereby the gas stream is divided into one portion entering the traps and another portion passing through the baflle spaces and between the traps, and whirl producing baffles in said traps.

9. In an apparatus for separating dust from gases, a gas flow chamber, a plurality of dust collecting chambers, spaced traps leading from said flow chamber to said collecting chambers, spaced deflector baffles in said flow chamber converging towards said traps, and passages between the divergent battles between adjacent traps said passages communicating the collecting chambers and the flow chamber.

10. In an apparatus for separating dust from gases, a gas flow chamber, a plurality of dust collecting chambers, spaced traps leading from said flow chamber to said collecting chambers, whirl producing bafiles in said traps, spaced deflector bafiles in said flow chamber converging towards said traps, and passages between the divergent baflies between adjacent traps, said passages communicating the collecting chambers and the flow chamber.

11. In an apparatus for separating dust from gases, a gas flow chamber, a series of independent dust collecting chambers, conduits leading from said gas flow chamber to said dust collecting chambers, and foraminous bafiies in said dust collecting chambers for receiving the dust-laden gases from said conduits.

12. In an apparatus for separating dust from gases, a gas flow chamber, a series of independent dust collecting chambers, conduits leading from said gas flow chamber to said dust collecting chambers, additional conduits leading from said dust collecting chambers to said gas flow chamher, and foraminous baffles in said dust collecting chambers adjacent the openings of said additional conduits.

13.v In an apparatus for separating dust from gases, a gas flow chamber, a series of independent dust collecting chambers, conduits leading from said gas flow chamber to said dust collecting chambers, whirl producing baflies in said conduits to set up free spiral vortex flow of the gases therein, and foraminous bafiles in said dust collecting chambers for receiving the dust-laden gases from said conduits and breaking up the vortex flow.

14. In an apparatus for separating dust from gases, 9. gas flow chamber, a series of independent dust collecting chambers, conduits leading from said gas flow chamber to said dust collecting chambers, whirl producing baflies in said conduits to set up free spiral vortex flow of the gases therein, additional conduits leading from said dust 5 collecting chambers to said gas flow chamber and foraminous baflies in said dust collecting chambers adjacent the openings of said additional 'conduits.

15. In a process for separating dust from fiowing gases, the steps of separating a portion of a dust laden gas flow, cleaning the separated portion, returning the cleaned separated portion to mix with the remaining dust laden gas, and again separating a portion of the mixture, cleaning the separated portion, and returning the cleaned portion to again mix with the remaining dust laden gas.

16. In a process for separating dust from flowing gases, the steps of directing a portion of a dust laden gas flow towards a trap to build up a gas pressure at the trap entrance, sharply deflecting the remaining dust laden gas to increase the dust content of said portion, utilizing the flow of the remaining dust laden gas to produce a low pressure at the trap exit, and imparting a whirling motion to the dust laden portion, whereby a centripetal dust concentration is produced.

17. In a process for separating dust from flowing gases, the steps of directing a portion of a dust laden gas flow towards a trap to build up a gas pressure at the trap entrance, sharply deflecting the remaining dust laden gas to increase the dust content of said portion, utilizing the flow of the remaining dust laden gas to produce a low pressure at the trap exit, imparting a whirling motion to the dust laden portion, whereby a centripetal dust concentration is produced, and breaking up the whirling motion to separate the dust.

18. In a process for separating dust from flowing gases, the steps of directing a portion of a dust laden gas flow toward a trap to build up a gas pressure at the trap entrance, sharply deflecting the remaining dust laden gas to increase the dust content of said portion, utilizing the flow of the remaining dust laden gas to produce a low pressure at the trap exit, imparting a whirling motion to the dust laden portion, whereby a centripetal dust concentration is produced, breaking up the whirling motion to separate the dust, and returning the cleaned gases to mix with the remaining dust laden gases.

HUDSON H. BUBAR.

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