US2420217A

US2420217A - Automatic dust removing system

Info

Publication number: US2420217A
Application number: US483275A
Authority: US
Inventors: Frank B Allen
Original assignee: Allen Sherman Hoff Co
Current assignee: Allen Sherman Hoff Co
Priority date: 1943-04-16
Filing date: 1943-04-16
Publication date: 1947-05-06
Anticipated expiration: 1964-05-06

Description

May 6, 1947.

' F. B. ALLEN AUTOMATIC DUST REMOVING SYSTEM Filed April 16, 1943 6 Sheets-Sheet L mmvrox. PEA/VA a. nun! ATTORNEYS May 6, 1947. F. B. ALLEN I AUTOMATIC DUST REMOVING SYSTEM Filed April 16, 1943 6 Shegts-Sheet 3 INVENTOR. F/PA/Y/F .B- AZAE/V A 7T0/P/VE May 6, 1947. F. B. ALLEN 2,420,217. 7 AUTOMATIC DUST REMOVING SYSTEM Filed April 16, 19 5 e Sheets-Shed 4 A T TOENEYS May 6, 1947.

F. B. ALLEN wwouguc nus'r nsuovme sYsTsI .Filed April 16, 1943 6 Sheets-Sheet 5 INVENTOR. flAA/A' .B- AllE/V Q BY aw, M

May 6, 1947.

F. B. ALLEN AUTOMATIC DUST REMOVING SYSTEM Filed April 16, 194s e Sheets-Sheet 6 NMY A 7'7'0/PNEY5 A m mm mA 9%) i I I m A W8 m \S B Q s3 w N3 c c M E i R L. X B

Patented May 6, 1947 UNITED ES- RATEN T OFFICE AUTOMATIC DUST nEMovmesYsrEM' ,Frank B. Allen, Lower Mei-ion Township, Montgomery County, Pa., assignor to The Allen- Sherman-Hofl Company, Philadelphia, Pa., a corporation of Pennsylvania Application April 16, 1943, Serial him-483,275

6 Claims. 2

This invention relates generally to the art of handling finely divided solids, and more particularly to a new and improved system, method and apparatus for handling dust. which is collected in powdered fuel-burning furnaces.

In modern steam generating stations which burn powdered fuel considerable quantities of finely divided incombustible solids are produced as residues of the combustionof the fuel. These solids, which are variously known as dust, fly ash, preclpitator ash and the like, will bereferred to hereinafter'coliectively as dust.

In the operation of powdered fuel-burning furnaces, part of the incombustible material in the a fuel melts in the combustion chamber and is solidified and collected in hoppers from which it is periodically removed for disposal. Other fine parts of the incombustibles which are-not melted are carried out of the combustionchambe! with the hot gases. Some of this dust is separated from the gases in the boiler tube chambers by reversal of thedirection of flow of the gases which is caused by bames and is collected in hoppers from which it must be frequently removed and handled. Some of the dust. passes thru the boiler tube chambers and is precipitated'out of the gases before entering the stack by any well known electrical or mechanical precipitator and is collected in hoppers from which it must be periodically removed and handled. The dust which escapes from the combustion chamber is nuisance material for .it can not be allowed to pass out thru the stack and menace the health of people and value of property and it is diflicult and expensive to collectand handle. Since many tons of such dust are produced daily by a large powdered fuel-burning furnace, theseriousness of this dust nuisance is obvious.

Ever since powdered fuel fired steam boiler plants came intouse efiorts have been made to solve this dust nuisance by handling this dust effectively and efllciently, but so far as I know none of these efiorts has been entirely satisfactory. Several conflicting factors are involved in the handling of'thls' dust.,

Since the dust is very fine and hot and since a partial vacuum anda strong draft exist within the furnace, it is impracticale to remove the dust ner, that is, by opening the bottom of the hopper and letting the dustfall out by gravity. Some of the dust so dlschargedwould be picked up and blown around in the power plant andsome of it:

would be .carried up out of the-hopper and into the gases in the furnace or adjacent to the stack.

2 It has been proposed to g the hoppers by means of currents of air flowing thru hopper valves under the influence of suction or vacuum. This proposal possessescertain diihculties. Since the dust tends to settle out of an air streamwhen it, moves slowlyor stops, it is i important that all the" dust. be removed from thevacuum in the separator had to be broken each time dust was discharged from it, it is obvious that the flow of air through the dust valve and piping must be interrupted with consequent settling out of dust in the pipe lines. If, to avoid such breaking of the vacuum, the separator is made large enough to receive all the dust from one hopper, the cost is high and the separator may require more space than is available for it; and even then it must be emptied before dust is removed from the next hopper and that means breaking and again building up the vacuum in v the system. Thus such a system requires arioperators attention and is. slow andinefiicient and expensive.

. The present invention reconciles the foregoing various conflicting factors and providesa new and improvedsystem and method, as well as new and improved apparatus, for effectively and emciently solving this dust handling problem.

The present invention may bebriefiy described as follows: The dust which has been collected from the furnace hoppers in the ordinary manin a, plurality of hoppers communicating with the interior of a powdered fuel furnace, is removed from the hoppers, one after another in succession, and is carried through passages to a device for separating gases and fine solids, for example,

- a'cycl'one separator. This movement of the dust is accomplished by means of gas which is caused to moveat adequate velocityby vacuum. The

dust and gas are separated in the separator, the

dust collectingin the bottom of the separator while thegas is withdrawn therefrom. The colremove such dust from Furthermore, the dust discharged from the separator is not in a condition for ready handling for it is finelydivided and will be picked up by any air currents which come into contact" with it. i

, control switch 2| on the same panel the dust has been removed from one nopper the foregoing steps are automatically car- 10 another hopper and are ried out on the dust of hoppers have automatically repeated until all been cleared of dust.

By means of this invention dust may be' continuously and automatically withdrawn from one hopper after another ing gas streams, separated from the gas and removed from the zone of influence of vacuum without breaking the condition of vacuum, and such separated dust may be wetted or otherwise conditioned for further handling.

In the drawings accompanying and forming a part of this application,

'Fig. 1 is a diagrammatic view of one form of system and apparatus embodying the present invention and with which the present invention may be practiced;.

Fig. 2 is a side elevational view, partly in section, of parts of the apparatus of Fig. 1;

Fig. '3 is an enlarged side elevational view, partly in section, of a dust valve of Figs. 1 and 2 with associated mechanism.

Fig. 4 is a top plan view of the separator and associated mechanism of Fig. 2;

Fig. 5 is a vertical, cross-sectional view, on line 5-5 of Fig. 4;

Fig. 6 is a horizontal, sectional view, taken on line 6-6 of Fig. 5;

Fig. 7 is a vertical longitudinal sectional view of the dust conditioner of Figs. 1 and 2;

Figs. 8, 9 and 10 are transverse sectional views taken on lines 8"8, 9-9 and Ill-I0 respectively of Fig. '7; and

Fig. 11 is a wiring diagram of an electrical system for controlling the operation of the dust valves of Figs. 1 and 2.

in Fig. 1 each of a plurality of dust hoppers I taken is provided with a dust valve 2. Groups of these valves are connected to thrustors 3 for actuation and each of the valves is connected to a pipe line 4 which leads to a separator 5. This sep-- arator communicates thru dust-withdrawal means 6 with a storage hopper I, which in turn communicates with dust conditioning apparatus 8 from which conditioned dust may be discharged into transporting means such as car 9. Main water line III is connected-to device II which serves to create and maintain a vacuum in line I2 which is connected to separator 5 and line l and thru branch line I3 with vacuum gage Il on the operators panel I5. A branch water line It leads from main water line III to water pressure gage I! on panel I5 and communicates with branch lines I8 and I9 which lead into valves 20 and 2| which serve to break the vacuum in line I2. On panel I5 the rectangular area 22 indicates a space for signal lamps (not shown) to indicate various stages of operation of the various parts of the apparatus. Power switch 23 on panel I5 is the main power line switch, while enablesthe operator to vary the normal sequence of operations of the electrical circuits and parts controlled thereby. The water line III is provided with a shut-off valve Illa and the vacuum, line by vacuum induced movinterior of its hopper.

I2 is provided with another shut-ofl valve l2a. The device II may be of any form suitable for utilizing water to create vacuum, for example, a device of the general type disclosed in U. S. Patent No. 140,017, or preferably the Hydrovactor manufactured by The Allen-Sherman-Hoff Company of Philadelphia, Pennsylvania. This Hydrovactor is generally similar to the device of Patent No. 140,017,-but specifically includes, as is shown in Fig. 2, a housing Ila having a Venturishaped axial passage IIb and an enlarged end portion IIc into which a high pressure water line IId opens. The vacuum line i2 extends thru the enlargement No, as is indicated at Me and water escapes at high velocity from housing I I0 into the passage I Ib thru a plurality of nozzles II which are disposed around extension lie of line I2 and are inclined to project streams of water which converge just before reaching the smallest part of the passage IIb.

It will be evident from the foregoing description of Fig. 1 that the present invention includes several inter-related, but diiferent, types of systerns, viz: a vacuum system, a mechanical system, a hydraulic system and an electrical system. The vacuum system may be considered as comprising the dust valves 2, line 4, separator 5 and line I2. The mechanical system may be considered as comprising the device I5. The hydraulic system may be considered as comprising the circuits of Fig. 11 and the devices controlled thereby including the thrustors 3.

In Fig. 2 parts of the apparatus of Fig. 1 are 'shown in somewhat more detail. There two of the hoppers I are disposed beneath electrical precipitators 25 to receive dust precipitated from furnace gases traveling from the tube chambers of a powdered fuel burning furnace to the stack. The lower pair of hoppers 25a correspond to hoppers positioned to collect dust separating from the furnace gases in the tube chambers of such a furnace. Each of these hoppers is provided with a dust valve 2 which is shown in more detail in Fig. 3.

Each valve 2 comprises a housing 26 the interior of which is in communication with the At one end the valve has an air inlet pipe 21 in which is a check valve 21a to admit air but to prevent escape of dust, and at the other end has an air and dust outlet pipe 28 which connects the valve to pipe line 4. If desired, the inlet pipes 21 may be connected to the interior of the adjacent hoppers above the top of dust in the hoppers. In that event, gases from the hoppers would be drawn thru the valves instead of air. The outlet opening is controlled by a door. fastened to shaft 29 which is rotatably mounted in housing 26 and which may be rotated by a lever 30 fastened thereto and engageable with a cam 3| keyed to a shaft 32. To insure the free movement of dust 'from hopper I into dust valve 2 a vibrator may be employed which, as is shown in Fig. 3, includes a plate 33 pivoted at its upper end within the hopper and attached at its lower end to a rod 34 which may be reciprocated by motor 35.

As is shown in Figs. 1 and 3, several hoppers l are served by a single thruster 3 thru the medium of shaft 32. Each thruster comprises a hydraulic cylinder and piston and a centrifugal pump for forcing liquid into the space within the cylinder and beneath the piston, thereby raising the piston by a rod 35a: This rod is pivoted to the arm 36 of a member 31 which is mounted to rotate on shaft 32 and which carries a pawl to engage with ratchet 38 which is secured to shaft 32. When the rod 35a is forced upwardly the pawl engages the ratchet 38 and rotates shaft 32 thru a predetermined angular distance, and when the centrifugal pump is -de-energized the piston moves downwardly in its cylinder under the influence of gravity, thereby pulling the rod 36 down and'retracting the pawl to engage'with the ratchet for the next operation of the thrustor. I

It will be understood that several cams 3| on any shaft 32 are so disposed around the shaft that when one pawl engages its lever 30 to open the door of its valve the other 'pawls will not be in positions to open the doors of their valves; and that as onepawl 3| moves out of contact with its lever 30 so that the latter may move downwardly and its door may close, another cam- 3| will be engaging its lever 30 to open the door of the associated valve.

The dust valves above described and other forms of valves which might be employed are shown and described and claimed in my copending application Ser. No. 464,720, filed November 6, 1942, as a continuation-in-part of application Ser. No. 429,269, filed February 2, 1942, now Patent 2,368,395, issued January .30, 1945. The

thrustor and its valve-actuating"means are shown; described and claimed in my copending application Ser. No, 470,472, filed December 29, 1942, now Patent 2,368,396, issued January 30, 1945.'--

Thedust valves 2 of Figs. 1 and 2' communicate by the legs 54 which support separator I! and partly by other legs 55. As illustrated, the housing 531s, in plan view, a rectangle with rounded ends. Within housing 50 and near the ends thereof are mounted two vertical shafts 58 each having keyed thereto a" sprocket wheel 51. One of these shafts 56 is an idler shaft while the other one is driven. This driven shaft is attached to a" pulley 5'8. A motor 59 working thru reduction gearing 50, pulley BI and belt 82, which is trained around pulleys 58 and BI, serves to rotate the driven shaft 56 and its sprocket wheel 51. An

qendless chain 65 provided with transversely extending disc-shaped members which may be called pistons, is trained around sprockets 51 and when one-sprocket 61 is rotated this chain is driven and in turn drives the other sprocket.

The direction of travel of chain 65 is indicated by the arrows in Figs.'4 and '6.

To minimize sagging of thechain 85 hollow cylinders 61 are disposed adjacent to each'sprock- 'et 51, as is best shown in Fig. 6. The bores of these cylinders 81 are slightly larger in diameter than the pistonsGS, and cylinders 61 are so pothru lines 28 with line 4 as above described.

This latter line leads into separator 5. While various types of separators may be employed, a satisfactory type is that shown in some detail in Figs.4,5and-6. Separator 5 consists of a receptacle having side walls 40, a bottom wall 4| provided with outletopenings 42 therethru, a-bottom wall 43 which slopes downwardly toward each opening 42. an access door 44, a top cover 45, and an annular, inverted, U-shaped in cross-section sitioned within the housing 50 that the lower edges of pistons 66 will engage the lower inner surface'of the cylinders when the chain is substantially horizontal or free from sagging. v

Openings 42 communicate with the interiorof two elongated cylinders 10. These-cylinders. are preferably provided with water Jackets-1| into which cooling water may be led thru pipes and from which water may be carried away thru pipes 13. These cylinders 10 surround the endless chain 65 and are aligned therewith so that the chain may pass axially .therethru. The diameter of the .bore of each cylinder 10 is substantially the same as the diameter of pistons 86 at operating temperatures. As a result of this member46 adjacent to the inner side of the cover 45. Line 4,0pens tangentially into the U-shaped interior of member 46, as is indicated at and more, may exist.

relatively close fit between-the peripheries of the pistonsBB and the inner surface of cylinder 10 little, if any, air can pass thru cylinder 10 from hopper 53, where atmospheric pressure may ex-' ist, to the interior of separator 5 where a vacuum amounting to as much as 5" of mercury, or even Furthermore; the pistons 65 2 serve to propel dust whichpasses thru openings 42 to theends of the cylinders 10, where it falls into theupper end of hopper 53 between the adjacent ends of

cylinders

61 and 10.

, The pistons 66 may take several different forms.

The preferred form, which is illustrated in Figs.

out thru opening 48 into line I2 while thedust' will separate from the 'air' more or less completely and will collect on the'bottom walls 4| and 43 of separator 5.

Device 6 for transferring dust from separator 5 to storage hopper I is shown generally in Figs. 1

and 2 andin some detail in Figs. 4, 5 and 6. This transfer ap aratus 6 is enclosed in a housing 50,

, a part of the upper wall of which is wall 4| of separator 5, the side walls of the housing being indicated at 5| and the bottom wall52 having a i .circular opening to receive the open upper-end of a conically shaped hopper 53whichcommunicates with the interior of storage hopper 1. Since the dust to be handled is extremely fine,ri t is important that all the joints of housing 50 should be tight enough to prevent passage of dust therethru. Thishousing 50 may be supported partly 5 and 6, comprises a pairof mutilatedmetal discs 15 spaced a predetermined distance apart and smaller in diameter than the bores of

cylinders

51 and 10, and a disc 16 which is preferably composed of rubber or flexible, substantially noncompressible, material. These discs 16 comprise a thin portion lying between mutilated discsv 15 and extending therebeyond to engage the inner surface of cylinder 10, and=a thickened sectorshaped portion substantially as thick as the combined thickness-of discs 15 and the thin portion of 16. In other words, the plates '15 are discs which have been mutilated by removal of sector portions and the member 16 has been thickened to occupy the space provided by removal of, those sector-shaped portions. The thickened portions of member .16 are disposed at the lower sides of piston '66 so that they will carry part of; the weightof the chain by engaging the lower portion of "theinterior surface of cylinder 10 while the thinner portions of member 16, which do not have tobear'such weight, need only seal the cylinder against passage of material amounts of upper end and is provided on air thru the cylinder and also propel dust from opening 42 to the end of the cylinder.

It will be understood that when dust isbeing separated in separator 5*from the air which transferred it from hopper I to the separator, the transferring device 6 should be in operation. When operated and dust is present in separator 5 the dust'slides down bottom wall 43 and feeds into openings 42 and thence into the interior of cylinders I0. The moving chain 65 propels pistons 66 thru cylinders I and moves the dust from openings 42 to the end of the cylinders, where it may fall into hopper 53. Even the a considerable vacuum may exist in separator and atmospheric pressure may exist in hoppers 53 and I, no material amounts of air can pass thru cylinders into separator 5. As a result, dust may be continuously withdrawn from one-after another of a plurality of hoppers 2, continuously separated from the air in separator 5, and continuously transferred to hopper I without any material disturbance of the condition of vacuum being caused by the transference of the dust from the separator to hoppers 53 and I. In other words, a separator 5 of modest size can be used in this manner and yet many tons, of dust may be removed from a plurality of hoppers without the necessity of breaking and again building up the condition of vacuum at short intervals of time.

Figures 7 to 10 inclusive show in greater detail a hydraulic apparatus which is indicated generally by reference numeral 8 on Figs. 1 and 2. As shown on these latter figures, device 8 is in communication with hopper I thru a conduit 80 which is provided with a slide valve 8I and a rotating valve 82 actuated by motor 88.

Device 8 comprises a stationary, tubular feeder 85, a rotatable tubular mixer discharge tube 89 which has an opening 80 in its lower portion to deliver material therefrom into a transporting device such as hopper car 8. Means 85 and 86 are axially aligned and are inclined downwardly by supporting frame-work 8|.

Referring more particularly to Fig. 7, it will be seen that member 85 projects at its lower end into the upper end of member 86 and that these adjacent ends are sealed against escape of dust by a housing I00 within which is located a ring gear IOI attached to the upper end of member 86. This ring gear meshes with a pinion on motor I02. Member 86 isprovided with exterior annular tracks I03 which rest and run on rollers I04. The lower endormembers 86 extends into housing 89 and has a fairly dust-tight connection therewith, as indicated at I05.

A spider H0 is secured to member 86 near its the axis of member 86 with a tubular bearing III on one side thereof and with a driving socket I I2 on the other side thereof. A screw conveyor H8 is disposed in member 86 with the outer edges of its spiral veins II4 lying fairly close to the inner surface of member 85. As shown, this conveyor has a stub shaft H5 at its upper end rotatably positioned in bearing H6 and at its lower end a stub driving shaft II! which seats in driving socket II2. It will be understood that when' member 86 is rotated driving socket II2 of spider IIO will rotate screw conveyor H8 and will move dust from the lower end of conduit 80 into the upper end of member 86.

A cylindrical member I20, which may be a length of pipe, has its upper end rotatably 75 86 and a stationary mounted in bearing III of spider H0 and its lower end supported and held against rotation by housing 89. When member 86 rotates this cylinder I20 does not rotate. h

-Member I20 has secured to it within member 86 two axially spaced baflles I2I. These baflles are substantially alike and are shown in side elevation in Figs. 8 and 9. Preferably, baIIles m are slightly less in radial length than the radius of member 86 and have peripheries which are slightly less I2I is preferably provided at its lower edge with an adjustable and replaceable shoe I22, for I have found that these baiiles tend to wear away more quickly at that place than elsewhere.

The cylindrical member I20 also has secured thereto a plurality of scrapers I25 spaced therealong. These scrapers extend out close to the inner surface of member 88 and serve to prevent mixtures of dust and water from clinging to and rotating with the member 86.

A water line I extends in thru the end wall of housing 81 and is provided with a plurality of nozzles I8I, I82 and I88. A branch pipe I84 is provided with nozzle I85. Pipe line I80 ll attached to member I20.

It will be understoodthat when dust is delivered from hopp r I 85 and drum 86 is rotating the dust will be propelled thru member 85 by conveyor H8 and dischanged into member 86. Water sprayed onto the dust from the nozzles of pipes I80 and I84 will moisten the dust and cause it to ball up as it moves toward the lower end of rotating member 86. This moist dust tends to fill the spaces between bailles I2I and the interior surface of member 86 and seal them against egress or dry dust while the scrapers I25 prevent the moistened dust from clinging to and rotating with the drum and scrape the moist masses from those walls and drop them onto the far side of the adjacent baflles I2I. The water sprayed into member 84 is regulated in accordance with the amount of dust therein, so that the dust will be moistened and the particles will cling together much like moist earth, and such moist masses will be discharged from the lower end of member 88 where they can pass thru opening 80 into a conveyance.

In that condition these masses are substantially.

free from dry dust which could be blown away.

In Fig. 11 are shown electrical circuits for actuating the thrustors 8 to open and close a plurality of valves 2 in sequence and in accordance with the degree of vacuum existing in the vacuum system.

Fig. 11 shows power lines I48 and I which may be connected to a suitable source or power thru switch 28 on panel I5. Several circuits, A. B, C and D, are associated with lines I40 and I and the first three of these'circuits include banks of contacts E, F and G and rotatable switches or selectors H, I and J. These contacts and selectors constitute parts of a switching device which is made and sold by the General Electric Company and is known as an Automatic Supervisory Switchgear Multiposition Selector. The switches H, I and J are mounted on a rotatable shaft and move simultaneously when the shaft rotates.

In circuit A line I42 connects power line I with fixed terminal I43 of the selector while line I44 leads from power line I40 to switch I45 which is connected thru point 0 of the E bank of contacts with the movable switch H. Switch I45 is control switch 24 on panel I'l. When switch I45 is closed current will flow thru the aforesaid cirthan in extent. Each baflle thru conduit 80 and into member cuit and energize the selector matching coils, the selector thereby shifting switches or selectors H, I and J from points to I of each bank. Current will thereupon flow thru line I50 of circuit B, bank G and line II of circuit C thereby energizing contactor NI of the latter circuit, this contactor in turn closing contact I 5'2 of circuit D and energizing thrustor I53. This thrustor I53 is one of the thrustors 3 of Fig. l. The thrustor is actuated by actuation of its motor which drives the pump of the thrustor. When actuated the thrustor rotates shaft (i2 of Fig. 3 to open the outlet door of a valve 2 thereby permitting the vacuum in the system to induce a flow of air thru the valve. If the vacuum in line 4 was above the predetermined amount when the dust Valve was opened contact VU of a vacuum relay in line I48 closes and energizes relay TI and contacts on TI close and energize relay T2. Contacts on relay T2,

close and energize the selector notching coils to step the selectors H; I and J to points 2 on banks E, F and G.

When the vacuum in the system falls below a predetermined value, contactor VD in line I41 closes and causes the selector notching coil to operate thru relays TI and T2 and move the selector to points 3. This operation takes place when substantially all the dust has been removed from the first hopper.

When the selectors are on points 3, contactor pers I which the operator desires to remove, the furnace operator opens valve Illa in main water line Ill thereby admitting water under pressure predetermined minimum amount as recorded by gage I! on panel I5 the operator closes main power switch 23 thereby energizing power lines Mil-and I of Fig. 11. Then the operator shifts control switch 24 to the starting position thereby energizing the selector and shifting the contacts thereof inbanks E, F and G to the P int I position. Thereupon the thrustor for the first group of dust valves 2 is actuated with the resultant opening or the door of the first valve of this group of d'ust valves 2. Air under the in-- fluence oi the vacuum existing in the system Lfiows 'thru the valve, entraining with it dust from the hopper and carrying that dust thru line 4 and into separator 5 where the dust and air are separated-the dust collecting in the bottoinof the separator while the air escapes thru I so NI is again energized and thrustor I53 is operated thereby rotating shaft 32 enough to move cam 3| out of contactwith lever thereby allowing the door of that valve to close, and moving another I cam 3| against its lever 30 thereby opening the door of that valve. The vacuum increases in the system as soon as the door of the'va'lve of the empty hopper is closed and when it reaches the predetermined amount relay VU closes. Then the operations which are described above after the closing of relay VU are repeated. These opera tions are repeated for each valve on the first thrustor.

7 When the last hopper associated with the first thrustor is emptied of dust the select'ors'have .been stopped to point 9. Thereupon contactor N2 in line I54 is energized and the second thrustor I53 a is' energizedithru contact I52a and opens the first valve of the group of valves controlled thereby. At the same time contacts of GI in line I60 of circuit B energizecontactor NI to close the, last valve of the first group of valves.

This sequencing "continues thru the third thrustor, (orthr'u'more'than three thrustors provided, thei necessary additions are made to the circuits 'floi Fig; 11) until the selector reaches the 0 pointwhi'c'h is an open switch in the circuit to bani; E. jflfh'e switch '24 must be closed before the above' described operations can be repeated.

flhejcohtacts, VU and VD, have connections associated with vacuum gage I4 of panel l5 (Fig. 1). ContacttVD jis closed bythese connections while the vacuum gage I4 registers from zero to some predetermined extent otvaouum, for example, 5"

ormercury, and contact'VDis open while the vacu'um is greater than that predetermined amount.

line. I'hedust which is separated in the senarator flows thru openings 42 and is propelled by the pistons on conveyor 651:0 the ends of the cylinders 10 and is there discharged into the' upper end of hopper 53 and thence falls into storage hopper "I; When substantially all the dust has been removed from one hopp r oi the first group of hoppers andthe "vacuum decreases a .in the line, the selector automatically actuates;

the' thrustor of that group oi'valvesthereby'perflmitting the closing of the door of thejust emp-,

tied Jhopper valve and opening-the'door or I next valve.

I This sequence! of operations is repeated forg each of the valves ofthe' group associated with the first thrustor and continues thru the next group of valves associated with the second thrustor and so on to the successive group of valves and their thrustors until substantially all the dust has been removed from all the hoppers, whereupon the selector arrives at an open switch and the electrical system ceasesto function until re-energized by movement of the control lever :24 to the starting position.

During all this time the dust transferring device 6 has been transferring dust from separator Contact VU is open while the vacuum is below a predetermined value, for example, 8'' of mercury but is closed while higher values exist in the sys-' tem. w

The operation of the above described apparatus is substantially as follows: Assuming that the various described parts have been-installed and connected as shown and described, and that'there is an accumulation of dust in a pluralityv of hop 'E-to storage hopper 1..

When the dust has all been removed from th several hoppers the operator closes valves I Ila and 12a. Since it is desirable that there should be no fiow of water in line l2, means are provided for drainage of water out of water line 5..

While the water pressure is on this line water fiow's thru branch lines i8 and I 9 and the pressure of water in line I8 actuates valve 20 to close the drain valve connected to branch line I9. When valve I0 is closed the pressure on water in line IE falls by reason of the water in that line escaping thrudevice II and coincident with that fall in pressure the piston in valve 20 is restored to normal position, thereby opening the. drain .valve in line I9 and permitting water to escape 1 therethru. As this water pressure decreases the spring in-valve 2| opens that valve and permits air to flow therethru and into line I2. water drains out of the system without backing 'up-in line I2.'

It will be understood that the dust in hopper 1 must be removed therefrom but may be removed only at fairly long intervals such as once a day or so because of the large capacity of hopper when dust is to be removed from hopper l the motor I02 is energized, thereby rotating conveyor Ill and drum 86. Water is admitted into lines I30 and I34 to discharge thru the several spray nozzles I3I, I32, I33 and I35. The slide valve 80 is Opened and rotary valve 02 is set in motion by energizing motor 83. Thereupon dust in hopper I passes thru conduit 80 and into member 85 where it is propelled by a conveyor II3 into drum 86. There it is mixed with the water from lines I30 and I34 and the moistened or wetted'dust discharged from the lower end of drum 30 discharges into a conveyance such as car 0.

Since the dust discharged into hopper I displaces air therein, some venting means should be. provided to permit such displaced air to escape. Since the dust discharged into hopper I is extremely fine and tends to be moved by currents of air, the venting means should be such astopermit escape of air while preventing the escape of dust with the air. Any suitable means may be employed for these purposes but. as is shown in Fig. 5. a simple meansconsists of a finely woven fabric cylinder 200 which is attached to the walls 20I defining an outlet opening from the hopper I. This flexible cylinder 200 is enclosed in a housing 202 which has one or more outlet openings 203 on the top thereon The upper end of member 200 is preferably attached to a member 204 which has an extension in the form of a rod or chain 205 extending thru the top of housing 200. Thisextension 205 may be held in a position to maintain member 200 extended but member 205 may be reciprocated thereby shaking member 200 and dislodging from the interior thereof any dust which may be adhering to it.

It will be seen from the foregoing description that the present invention provides a system, method and apparatus which will remove dust from a plurality of hoppers in succession by air moving thru a vacuum system, and that the dust entrained in the air is continuously separated therefrom and transferred to a chamber under atmospheric pressure without any interruption of the operation of the vacuum system; and that the dust in the latter hopper is so conditioned that it may be handled and disposed of without substantial quantities thereof 'being picked up by moving air currents. It will also be observed that the present invention provides a system, method and apparatus which are in part automatic and in part semiautomatic and which require the minimum amount of personal attention by an operator. It will further be seen that this invention makes it possible forone operator to remove periodically or substantially continuously, if desired, the dust produced by a large powdered fuel burning furnace and to handle many tons of such dust per day while preventing the dust from becoming a nuisance other than as regards the expense of the equipment and the small amount of labor cost for the operator. The cost of the apparatus is quickly offset by the savings in labor as compared with previous dusthandling systems and apparatus.

Having thus described the invention so that others skilled in the art may be able to understand and practice the same, I state that what I desire to secure by Letters Patent is defined in what is claimed.

What is claimed is:

1. A system for handling dust comprising a plurality of dust-collecting chambers, a dust and gas separating chamber, a vacuum creating device, a passage selectively connecting each dust collecting chamber with said separating chamber, and with'said vacuum creating device, an electrical circuit, means automatically actuated by predetermined amounts of vacuum in said passage between said collecting chambers and saidvacuum creating device to energize said electrical circuit, and control means actuated by said circuit when energized to shift said flow of gas from one dust-collecting chamber to another such chamber.

2. Apparatus for handling dust comprising a plurality of dust-collecting hoppers each having a dust discharge opening, a valve for each, hopper for receiving dust discharged thru the said opening thereof and having a gas inlet opening and a dustand gas outlet opening, a separator 16a.

separating said dust and gas, piping connecting said valve outlet openings with said separator, means associated with each valve for controlling the flow of gas and dust thru its dust and gas nections from ing in combination,

opening, a vacuum creating device for creating a vacuum in said separator and piping and, when the said outlet opening of any valve is open, for causing a flow of gas thru such valve and piping into said separator, electrical .means actuated by the vacuum existing in said pipe between aid valves and said vacuum creating device and operable to actuate said valve control means to opened and to closed positions, and means for removing dust from said separator while acon: dition of vacuum exists in the separator.

BIA material handling system comprising in combination, a plurality common discharge conduit for said containers, means for producing subatmospheric pressures in said conduit, a separate valve for each of said containers for completing and interrupting consaid containers to atmosphere and to said conduit, a selector switching device having a plurality of operating positions, means responsive to changes in atmospheric pressure in said conduit for successively actuating said .selector switching device to said operating positions, and means responsive to operation of said switching device to said positions ing and closing said valves.

4. A material handling control system comprisa plurality of material containers, a common discharge conduit for said containers, a separate valve for each of said containers for connecting said containers to said conduit and to atmosphere,:means for producing subatmospheric pressures in said conduit, a selector switching device having a plurality of operating positions, a starting control device for setting said selector switching device in operation, operating means for said valves responsive to operation of said selector switching device to said operating positions for successively opening and closing said valves, and a device cooperating with said selector switching device and responsive to a subatmospheric pressure in said conduit for actuating said selector switch to one of said operating positions and responsive to atmospheric pressure in said conduit for actuating said selector switch to a succeeding position.

5. Apparatus for handling fine solids comprising a plurality of hoppers to collect such solids,

of material containers. a

for successively opensaid system for successively a plurality of valves, one for each hopper, through which such collected solids may flow from said hoppers, each of said valves including movable closures, a passage for solids flowing from said valves, closure control means operatively connected with said closures, and an automatically actuated electrical system, said system including a device sensitive to different amounts of vacuum in said passage for energizing the control means of said valves successively to open one of said valves after an open valve'has closed.

6. Apparatus for handling fine solids comprising aplurality of hoppers to collect such solids, a plurality of valves, one for each hopper, through which such collected solids may flow from said hoppers, each said valve including a movable closure, closure control means operatively connected with said closures, an electrical system including switching means for successively energizing the control means of only one of said valves at a time, and an automatically actuated, vacuum sensitive device operatively connected with energizing said switching means.

FRANKBAILEN. a

REFERENCES CITED The following references are of record in the file of this patent:

, UNITED STATES PATENTS Number Name V Date 1,371,682 Jacoby Mar. 15, 1921 952,970 Whitmore Mar. 22, 1910 470,403 ,Robinson Mar. 8, 1892 960,857 Eggert June 7, 1910 2,310,603 Taylor Feb. 9, 1943 2,325,432 Simpson et al. July 27, 1943 1,943,780 Allen Jan. 18, 1934 851,054 Bassler Apr. 23, 1907 1,100,992 Sallee June 23, 1914 1,935,843 Goebels Nov. 21, 1933 1,815,403 Goebels July 21, 1931 FOREIGN PATENTS Number Country Date 7 576,769 German May 17, 1933- 313,232 German June 30, 1919 206,350 British Nov. 8, 1923