US2026633A - Apparatus for separating materials by fluid streams - Google Patents

Description

Jan. 7,- 1936. M. E. HAWORTH APPARATUS FOR SEPARATING MATERIALS BY FLUID STREAMS Filed May 26, 1951 2 Sheets-Sheet ,l

uhhsu Jan. 7, 1936. M. E. HAWORTH ,0

APPARATUS FOR \SEPARATING MATERIALS BY FLUiD STREAMS Filed May 26, 1931 2 Shets-Shet 2 FORWARD REVERSE //v VENTOR:

Mac/v E. Haworfh ATTY Patented Jan. 7, 1936 UNITED STATES APPARATUS FOR SEPARATING MATERIALS BY FLUED STREAMS Mack E. Haworth, Pittsburgh, Pa., assignor to The Jeffrey Manufacturing Company, a corporation of Ohio Application May 26, 1931, Serial No. 540,059

15 Claims.

This invention relates to the control of fluid streams; to an arrangement whereby a constant weight or buoyancy of fluid stream can be delivered irrespective of changes in pressure, temperature, humidity and/or resistance; and particularly to an arrangement whereby certain definite predetermined resistances may be automatically or otherwise maintained through the bed of coal or other mixtures of materials upon a deck or other pervious surface and being acted on by the fluid stream; and to the control of certain portions of the fluid stream within the system. The invention also relates to the automatic regulation of fluidstreams for purposes other than the separation of various mixtures of materials, such as the parallel operation of a plurality of blowers operating in connection with a common system of ducts; and to the-automatic regulation of drafts for boiler furnaces, cupolas, etc. I r

This invention is an enlargement upon certain portions of my companion application Serial No. 516,632, filed Feb. 18, 1931 for Fluid stream control.

In my work and study on fluidstream control and particularly in connection with the separation of mixtures of solid materials containing constituents of different specific gravities by means of fluid streams, I have found existing apparatus and methods unreliable, complicated and non-uniform. Many manual operations were necessitated which depended solely upon the judgment and skill of the operator with the concomitant disadvantages appreciated-by those skilled in this field. Such, furthermore, required close and exacting attention and were insufliciently sensitive to changing conditions.

The above and other defects and disadvantages have been overcome by my present invention, the obviation of which constitutes one of the objects of the present invention. I

It is another object of this invention to provide a sensitive, readily controllable arrangement for increasing the efliciency of the separation above indicated.

A further object is to efiectuate means for delivering a constant weight or buoyancy of fluid stream regardless of variations in the surroundmgs.

Additional objectslie in the features of control hereinafter specified and in automatic regulatory means to be described.

v Other and still further objects and advantages will be understood by those skilled in this art deck to values of buoyancy different from those in other portions of the deck.

I have also found that the regulation of the fluid stream in one or more sections of the deck changes the fluid stream flow through other sections of the deck unless certain corrections are made to bring the fluid streams through the other sections to their former values, when the desired regulation is accomplished in all sections.

As illustrated in Fig.1, a mixture of materials to be separated is fed onto the reciprocatory deck It through which a fluid stream is flowing from a suitable source. The deck may be divided into compartments or sections such as l |l2-|3- l4l5l6, etc. and means (not shown in this application) provided for regulating the flow of the fluid stream through each section independently of each other section. The value of the fluid stream, its buoyancy etc., are regulated according to the thickness of the bed of materials upon the deck as describedin my copending application S. N. 516,632. The reciprocatory means is diagrammatically shown at I IQ .So long as the thickness of the bed remains at a constant value the buoyancy of ,the fluid stream should remain unchanged for constant efliciency of separation. Under constant conditions of temperature, barometer, moisture, resistance and pressure the value of the fluid stream remains constant if the thickness of the bed remains un-' changed and the mixture of materials remains substantially the same, i. e., the mixture does not change sufiiciently to afiect the buoyancy required for free settling.

When there is a change in any of the variable 7 items,temperature, barometer, moisture, resistance or pressure,-it becomes necessary to change the volume of fluid stream per unit. of time in order to maintain the same effective buoyancies.

Again, if the moisture content of the materials upon the deck varies appreciably there will be a i change in the volume of fluid stream, by reason 2/ r i in resters, dampers, etc. to the flow of the fluid stream there will be a change in the volume of the fluid stream through the materials upon the deck.

I have found that it is possible to make all the corrections for any change in any of the variable items enumerated by new and novel means for the control of the fluid streams, some of which are referred to in my copending application Serial No. 516,632, and further that the corrections can be made automatically with the blower or blowers operating at a constant speedfadesirable operation because of the simplicity of the drives and lower cost of motors driving theblowers.

' As illustrated in the drawings, a duct l8. conhosts the deck hood 19 with the blower' 2!) of any'suitable type' and is provided with a damper 2|. A duct 22 connects the blower 29 with the dust'arre'ster 23 and may or may not be provided with a damper 24 similar to damper 2| The blower is provided with a bypass 25 which is fitted with" a damper 26 similar to dampers 2| and 24;

The blower 20 is operated ata fixed speed and against a predetermined total pressure. Damper 2"! is set to introduce a certain value or" ,artificial resistance which comprises a part of the total blower resistance. Damper 28 is regulated to permit only the desired 'volumes of fluidstream to be shortcircuited from the discharge or pressure side'of the blower to the suctionside.

Anelectrically controlled manometer M or other instrument or equipmentformeasuring the pressures developed in thefiuid stream is connected to the inside of the deck hood so as to measure the difference in pressure between the inside of the hood and atmospheric. Another similar instrument or equipment M is connected to either side of the blower 2D in order to record the total combined suctionand ,discharge heads or total pressure against which the blower operates.

"The 'dampers zl, 26, and 24 when the latter is used, are operated by meansof suitable mo tors 27, 28, 29 which when operatedin one direction close the duct or retrict the flow of fiuid stream'therein and when operated inthe opposite direction open the duct" or reduce the re; striction to the. flow of fluid stream therein. Motors 21, Z8, 25 are ofthereversible electric type, for example, and have the pinion gears 39, 3|,32; meshing with racks 33, 34, 3 5 suitably connected to dampers .25, 25, 2a respectively. The dampers may be suitably mounted in their respective ducts and may comprise anydesirable constructionper se, the drawings showing cooperablepairsof damper elements,'as an example, both of which are secured to the racks 33,34, 35, as shown: :1 7

. When the damper. E lis used in place of the damper 2 l or in. additionthereto the motor 29 for operating the damper tj l may'be controlled by means of apparatus the same in construction as that used for the motor 21 and operated by similar mechanism connected to the hood l9. Or if desired the relays 43, 48 may be used for controlling separate or additional forward and reverse electro-magnetic switches for the controlling of the supply of current from electric supply mains to the motor 29 so that at the same time that the switch 45 efiects the operation of the motor 21 the motor 29 will be likewise operated.

A mixture of material of a certain thickness of bed is fed onto pervious deck 10 for the purpose of separating the various component parts by taking advantage of the difference in specific gravities ofthe component parts. By determination it is found that in order to produce a condition in the mixture whereby free-settling takes place in the section II of the deck near the feed end, a difierence of pressure amounting to ac inches of water is required for settling 'theheaviest gravity material to the lower strata of the bed. "The" diiference in pressure required in othersections for settling the lighter gravity materials or finer materials may be less than the difference in pressure required for settling the heavier gravity materials and, if so, sufficient artificial resistance may be inserted under 'section'syl2, I3, l4, IE, IS, etc., to take up the difference between the pressure required at section II and the pressure required in the other sections. Hence the 'difierence in pressure between the area over any section of the deck, and atmospheric has the same value, while at the same time the pressures acting upon the mixtures of materials in various portions of the deck are different, the difierences amounting to the value of artificialresistances inserted under the various sections. The artificial resistances may be introduced by means'of louvres of the conventional types (not shown), by means of two matchedperforated plates one sliding upon the other so as topermit any desired portion of theareaof under the deck to be open to the flow of air, from zero percent of open area to the maximum allowed with all holes fully registering, or other suitable arrangements (not shown).

Having determined the pressure or water gauge required to producethe buoyancies for free-settling, fluid stream pressure equalizing pipe 36 is connected from'theinside of the hood 19 over the'deck It] to deck pressure regulator 31 which comprises two inverted bells 38 connected by balance bar 3 9 and immersed in a suitable liq- :1.

uid lill The balance bar 39 is balanced on a pivot point 4| and counterbalanced at 42. Pressure pipe 36 is connected to one bell and a pipe 43 connects the other bell to the atmosphere. The lbells are'sodesigned as to register the difference inpressure exerted uponthe m by pressure pipe 36 and atmospheric pipe 43 in inches of water, inches of mercury or other units of pressure best fitting the conditions or pressures obtaining. Liquid 4% is contained'in a suitable tank or receptacle 44.

The. balancebar 39 joithe regular 3l.is fitted with an arm 45,v or other suitable arrangements are provided, for operating contacts :5, 3'1. If a difference of pressure of :1: inches of water is required the contacts are so arranged that one contact i fiis just: above .r inches of water and the other contact" 4'! just below ml. Any change in thepvalue of :c. indicates a change ,in the pressures through the deck. and will result in a attests movement oithe bells as and arm 4s. It the pressure tends to increase, arm 45 will close the upper contact 46 which through suitable relays 48 illustrated will operate motor 21 and close damper 2| restricting the flow of air through duct I8 and the deck I until the difference in pressure has reduced to the original value 32". If the pressure tends to decrease, arm 45 will close the lower contact 41 and in a similar manner operate motor 21 in the opposite direction opening damper 2| to increase the'fiow of air through duct l8 and the deck l0 until the difierence in pressures has increased to the original 7 value x.

. midity.

By maintaining a predetermined difference in pressure between the area 'over the material bed on the deck and the atmosphere, corrections are in pressure or water gauge 2:.

automatically applied for a change in air density as follows: Air of a certain density flowing at a certain velocity through a bed of materials of a pending upon the velocity of the flow. There-' fore, as the density of the air increases or decreases, the resistance to the flow increases or .decreases and the difference in pressure, or water gauge increases or decreases. As the increase or decrease attempts to take place the deck pressure regulator 31 and contacts 46, 41 act to rotate the motor, operating damper 2| in the direction required to decrease or increase the pressure to bring it to the original predetermined value at.

Similarly, for any attempted change in the value x for any reason other than a change in air density, such as an increase in the moisture content of the materials on the deck which would increase the resistance to the flow of air and tend to reduce the air stream, or vice versa; a change in the resistance to the flow of air in duct H3 or 22; a change in dust arrester resistance etc.

- etc., damper 2| is operated in the proper direction to correct for the changed conditions thereb maintaining the predetermined value x Therefore, no attempt is made to provide any certainfflow of air through the deck asmeasured in cubic feet per minute, the basis upon which airstreams have been provided heretofore, irrespective of the variable and changing conditions mentioned, but provisions have been made for accurately providing the air streams required for producing and maintaining the buoyancies required for free-settling, the conditionsrequired for efficient and consistent separation by taking advantage of the difference in specific gravity of the various component parts of the mixturejof materials. a 1

The value x referredto may be any value "desiredin inches of water, inches of mercury,

'poundsper-square inch, etc. and the setting may be adjusted to any desired value within the limits "provided for any particular installation with the apparatus in operation or at rest. I

A blower operating at a constant speed and against a constant head will produce a constant 5 volume of air if measured in cubic feet per minute provided the density of the air does not change. The volume per unit of time varies, however, with changes in density, the change being directly proportional to the change in density.

In order to provide a blower operating at constant speed, a speed is adopted that will provide an excess of air over the range of operation for which the separating table is provided, the excess being transferred from the discharge to the suction side of the blower until such time as a portion or all of the excess is required through the system.

In order to provide for the blower operatingat a constant head, two pressure pipes 49 and 50 are provided to connect the suction and discharge sides of the blower 20 with a fan or blower pressure regulator 5|, constructed similarly to the deck pressure regulator 31 and operating in a similar manner. The prime numerals indicate each similarities. The total pressure or head against which the blower operates is predetermined and the volume of air produced at that pressure predetermined so as to provide an excess over the volumes normally required to maintain the difference in pressure 1: through the deck previously described. The difference between the volume required for pressure :c, under normal conditions and the volume produced by the blower under normal conditions is transferred from the pressure side to the suction side of the blower by means of bypass 25.

If the total pressure against which the blower has been designed to operate tends to increase or decrease, there will be a corresponding tendency for the pressure at through the deck to decrease or increase. However, through deck pres sure regulator 31, damper 2| is adjusted to correct for the change in total pressure or head; consequently, the total head is reduced to the predetermined value.

Due toleaks or air inlets on the suction side of the blower for dust suppression or other purposes, or outlets on the discharge side for desirable or unavoidable reasons, the volumes of air passing through ducts l8 and 22 maybe changeable while at the same time the volumes passing through the deck maybe unvariable. Therefore, with constant deck volumes variable total volume may be desirable. Therefore, the bypass serves three purposes, viz: to take care of the excess volumes produced by the blower, to maintain a constant head against which the blower operates, and at the same time provide variable volumes through the system with the blower operating. at constant speed against a constant head.

While damper 2! is adjusting itself to correct for any change in the total head against which the blower operates, fan pressure regulator 5| acts to energize motor 28, operating damper 26 in the bypass, opening or restricting the same to permit the excess volume to pass through the bypass notrequired through the deck for developing the'diiference in pressure :0, or for dust suppression or other purposes through inlets on the suction side or through outlets to the atmosphere on the discharge side, or for special purposes from the pressure side to the suction side through ducts other than the bypass.

. andmotor 21.

Thehoods; [9. over sections H to It .areisomewhat. constricted or convergent as at 52, thus acting as artificial resistances. As isknown, flexible side pieces 53 of suitable fabric or other materialare. used for the usual purposes. Inasmuch as. the fluid circulation sometimes. tends to, go inlithewrong, direction at the deck edges due to inflow of air, I may provide; a,pipe 54.leading from. the deck edge to the hoods l9 thusobvia'ting such tendency. This enhances eificient separation. Pipe 36 extends through the several hoodsand'has an outlet 55.in,each. These outletsv 55. are of the well known type which rnakethe pressure responsive device'M' respond toany changes in the velocity head of the air flowing through thebed on deck l0.

, Where blowers are used for producing a constant weight of air per unit of time against variable resistances; or where a plurality of blowersoperating against the same ordifferent total headsareconnected to acommon duct a similar arrangement of dampers, orv bypass ducts fitted with a damper or dampers, and bypass ducts fitted with dampers may be used to assure constant and efficient operation.

The: details ofthe control forthemotors 21 and 23 are shown .diagrarmnatically in Fig. 2, which shows, for purposes of illustration, the connections between the pressure regulator 31 It will be understood that the connections between the pressure regulator i and motor- 28 are in all respects similar, andthat motor 29- maybe provided also with a like control.

Whenthe pressiue. in the.b,ell,38,increases so as toliftarm 4-5, contact 55 on this arm will engage contact 45 and a circuit will be established from current supply line conductor L1 through conductor- 56, contact 55, contact 46, conductor 35a, coil 51, conductors 58, filland 54, back to conductor Lz' of the supply line. energized, closing the left-hand relay G8 I as viewed in Fig. 2, and establishing acircuit from supply line conductor L3, through conductor 50, conductor 66a, left-handrelay 48, conductor 6!, coil 62, conductor 63 and conductor 84, back to supply line conductor L2.

This energizes coil 82 and closesthecontacts of switch 55, makinga circuit through the motor 2] fromthe power line conductors L1, L2, and L2 to operate the rotor; 56 of the motor 2'? forwardly, to close the damper 2 i When the pressure under bell 38 drops suing -ciently to; allow the contact 55lto engage the lowercontact 41, the motor 21 is operated in the reverse, direction, effecting a. closingof dampers When,. contacts 55 and 41 close, circuit is made from thesupply. line conductor Lrthrough conductor 55, contacts 55 and s7, conductor. 67, coil 88 ofthe right-handrclay 5$, conductor-69,0011- ductors 59'and es to'the supply line conductor L2.

Theright-hand relay aiicloses, establishing a circuitfrom supply line conductor L3, through conductor 50, conductor l5, right-handrelay 38, conductor 'il, coil E2 of motor reversing switch I3, conductors-i i, 63 and 64 to the supply line conductor L 2. 7

This closes switch it and establishes a .circuit through the motor from the .power supply line,

in an obvious manner, to operate the rotor 66 in thelreverse direction soas to close the dampersZI.

It. will, therefore be seen that; the ,total resist-;

ance to .the fiowof air through-the'system will Coil 51 isv thus be ,automatically adjusted 4 responsively to variations in the conditions of the air stream and in tharesistanoe in..,the bed to. the. flow of the, air streamthroughthe, bed, so that the buoyancy or the air stream in the bed'will remain constant, 5 irrespectively of I such variations.

Iv have worked with other systems not so arranged andhave measured the volumes produced by. blowers at constant speed; connected to common. ducts. Ihave observed one blower in a ductdeveloping a part of its designed volumeand at the same time,- another blower producing only a small portionv of its designedvvolume. With the apparatus described the blowers can be fitted in a similar manner to. that described so that adjustments will be automatically made for any of the varying conditions described.

For boiler plants, cupolas, etc. where oxygen is :the element. desired in the air, blowers fitted with, the apparatus described are equipped to 2 produce the desired weight of oxygen per unit of time and they produce that weight of oxygen per unit of time irrespective of any changes that takeplace m'the density of the air or the pressures that take place in the system, through 5 which the air passes.

WhatI claimv as new and desiretov secure by LettersPatentisz. a

1. In a. system of the character described, a deck, hoods over said deck, means for creating suction over said deck between said deck and said hoods, and aconnection to said hoods from a point above said deck at the edge thereof to provide outward rather than inward flow at said deck edge.

2. In a system for pneumatically separating a mixture of material, the combination of a deck on whichsaid materials are supportedhfor separation, of suction hoods over said deck, a duct connected to, saidhoods at one end, a dust arrester 46 connected tothe other end of said duct, a blower in saidvduct, a..by-pass leading from the discharge side of said blower to the suction side thereof, avariable resistance in said duct, a Variableresistance in said by-pass, pressure responsive means connected between said first variable resistance and said hoods for automatically maintaining said suction in said hoods as to maintain substantially'constant the buoyancy of the air flow through said bed, and pressure responsive mechanism operatively associated with said variableresistance in said by-pass for short circuiting aportion of the fluid stream generated by said blower in saidduct.

'3. Ina system for separating materials by fluid streams, the combination with a tank, of liquid in said tank, apair of inverted bells in said liquid, at pivoted balance, bar connecting said bells, a counterweight connected to one end of said balance bar, a motor controlledby movements of said balance bar, a bedifor supporting the material to be separated, means comprising a constant speed blower and a duct for effecting a flow of air through said bed, an electrically operated damper for said duct controlled by said motor,and a pipeconnecting said duct to one of said bells,,and a pipe connecting the other bell to the atmosphere.

4. In a system for separatingmaterials by fluid streams, the combination with a bed for support- 70 ing material to be separated,- of means for maintaining substantially constant the buoyancy of air. flow throughsaid bed, regulating mechanism comprising an electrically operated damper, a motor for controlling said'damper, and. air pres- Cir sure responsive mechanism responsive to the velocity head of the air flowing through said deck for automatically controlling said motor.

5. In a system for pneumatically separating materials, the combination with a duct, of a ating a fluid stream, of a by-pass for said blower,

a variable resistance in said by-pass, and mechanism responsive to variations of diiference of pressure between the suction and discharge sides of said blower for controlling the resistance in said by-pass to maintain constant the effective volume of air supplied by said blower for the separation of materials.

'7. In a system for separating materials by fluid media, the combination with a duct, of a fluid stream generator for said duct and comprising a blower and a by-pass about the same, a variable resistance in said by-pass, and automatic mechanism connected to said duct on opposite sides of said generator to vary said resistance to maintain substantially constant the volume of. the fluid stream in said duct.

8. In a system for supplying a fluid stream at constant pressure and volume to a bed of materials, the combination with a support for such materials, of a duct communicating with the bed of materials, means dependent upon pressure in said duct for automatically regulating such pressure, a source of fluid pressure supply in the duct, a by-pass around said source of supply and communicating with said duct, and means dependent upon pressures in said duct for automatically controlling the flow through said by-pass to efiect regulation of the volume of the fluid supplied to said bed of materials.

9. In coal-cleaning apparatus, the combination with a deck adapted to support a bed of comminuted coal and impurities, of means for vibrating said deck, a duct communicating with the bed of material, means comprising a constant speed blower for generating the fluid stream through said bed of coal and impurities to effect separation of the coal from the impurities by stratification, means dependent upon fluid pressure in said duct for automatically regulating such pressure, and automatic mechanism associated with said constant speed blower to automatically regulate the volume of fluid passing through said bed.

10. In a system for separating materials by fluid media, the combination with a duct, of a fluid stream generator for said duct and cornprising a blower and a by-pass about the same, a variable resistance in said by-pass, and automatic mechanism connected to said duct on opposite sides of said generator to vary said resistance to maintain substantially constantthe pressure drop across said generator.

11. In a system for separating materials by fluid media, the combination with a bed adapted to support said materials, a duct connected to said bed, a fluid stream generator feeding said duct comprising a blower and a by-pass for the same, a variable resistance in said duct between said blower and said bed, a second variable resistance which is located in said by-pass, means responsive to the pressure drop across the bed and means responsive to the pressure drop across the generator, whereby said first and second variable resistances may be controlled as dictated by said responsive means.

12. In a system forseparating materials by fluid media, the combination with a bed adapted to support said materials, a duct connected to said bed, a fluid stream generator feeding said duct comprising a blower, means for maintaining constant the buoyant action of said fluid me dia regardless of changes in the density thereof comprising, means for indicating a change in change in the density or in the velocity thereof through said bed, and means for adjusting the flow of fluid through said bed, to maintain said condition of constant buoyancy.

13. In' a system for separating material by fluid streams, the combination with a bed for supporting material to be separated, of means for maintaining substantially constant the buoyancy of air flow through said bed comprising, regulating mechanism including a damper, means for operating said damper, and means responsive to the velocity head of the air flowing through said deck whereby the damper may be adjusted to maintain said condition of constant buoyancy.

14. In a system for pneumatically separating a mixture of material, the combination with a I deck on which said materials are supported for separation, of a suction hood over said deck, a duct connected to said hood at one end, a dust arrester connected to the other end of said duct, a blower in said duct, a by-pass leading from the discharge side of said blower to the suction side thereof, a variable resistance in said duct, a variable resistance in said by-pass, means including pressure responsive means associated with said hood whereby said first mentioned resistance may be adjusted to maintain substan tially constant the buoyancy of the air flow through said bed, and means including pressure responsive means associated with said duct whereby the second named resistance may be adjusted for short-circuiting a portion of the fluid stream generated by said blower in said duct.

15. In a system for pneumatically separating materials, the combination with a duct, of a blower in said duct, a by-pass connecting the suction and discharge sides of said blower, and means for controlling the flow through said bypass including means operable by the difference of pressure between the suction and discharge sides of the blower.

MACK E. HAWOR'IH.

Images