US2514333A

US2514333A - Automatic dust handling system

Info

Publication number: US2514333A
Application number: US735474A
Authority: US
Inventors: Lauritz E Mylting
Original assignee: Allen Sherman Hoff Co
Current assignee: Allen Sherman Hoff Co
Priority date: 1947-03-18
Filing date: 1947-03-18
Publication date: 1950-07-04
Anticipated expiration: 1967-07-04

Description

July 4, 1950 E. MYLTING AUTOMATIC DUsT HANDLING SYSTEM Filed March 18, 1947 July 4, 1950 L. E. MYLTING AUTOMATIC DUST HANDLING SYSTEM 6 Sheets-Sheet 2 Filed March 18, 1947 July 4, 1950 E. MYLTING AUTOMATIC DUST HANDLING SYSTEM 6 Sheets-Sheet 5 Filed March 18, 1947 INVENTOR. AOE/TZ E YL 7'//V6 July 4, 1950 L. E. MYLTING AUTOMATIC DUST HANDLING SYSTEM Filed March 18, 1947 6 Sheets-Sheet 4 f6 7 /ea /59 INVENTOR.

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UNITED STATES lPATEN T OFFICE :2,514,333 l AUTOMATIC DUST HANDLING SYSTEM Laurita E. Mylting, 'Merchantvilla NIJ., assigner delphia, Pag, a corporation 'of lie'nrisylvania` Application March 1s, 1947, serial No. 725,474

Claims. (o1. 3112-17) This Yinvention relates to the `art jof2 handling finely divided solids and more particularlytoa new and improvedfsystem, method, and apparatus for handling the ne dust which is carried by the gases out of vsolid fuel burning-furnaces. A,

In large boiler plants thedisposal uof ashhjas always been a difficult matter because ofthe large volume of material to ,be handled, the character of the material, zand the numerous points from which it must be collected. Specically, in steam generating plants employing solid f-uel a powder ash resulting from combustion settlesufrom Ythe gases into hoppers, for is precipitated electrically into hoppers. y

-One Asuccessful systemv for the disposition of this ash is disclosed in the application of lrank B. Allen, Serial No. 483,275, led April 16, 194B for Automatic Dust Removing System, now Patent No. 2,420,217 issued May c, 1947. In the Auen system, the finely divided ashis dra-wn off by air flow, induced by an aspirator, throughnconduits to a centrifugal separator or the like in which the lash is separatedfrom the air. The ash is then mixed with water andrdropped into `cars or the like for disposition. The .ash pipes are connected to the individual hoppers throughdust valves which normally remain closedto maintain the vacuum in the system except, of course, the "valve corresponding to the particular hopperjb'eing emptied. The dust valves, which are immediately below the hoppers, are opened and closed in the Allen system by electromechanical thrusters which rotate shafts extending to several valves and operating Athe valves mechanically in sequence.

The present invention may be regarded invsome respects as an improvement of the Allen system, particularly in the means for operating the various valves of the dust handling portion of the system. The hoppe'rs, dust separatonmeans lfor disposing of the dust, and vacuum producing device of the Allen System may be used with the system of the present invention. The principal objective of the'improved'system disclosed herein is to provide a simpler and more flexible control system for the .dust valves which will minimize the physical difficulties and expense of installation ofthe system, provide a more sensitive and responsive control of the operation of the dust valves, provide for selective operation of groups of the dust valves or of certainhdust valvesmonly, andrequire a lminimum of maintenance. The invention disclosed herein provides for substantially, fully automatic operation ofv the system. In addition, it provides for the incorporation of segregating valves `to isolate inactive sections of the dust conduit and thus minimize lair leakage into the Asystemrwith the consequent reduction of VaCuum and loss of `efficiency of the system.

A."Ihese objectives are `realized Vin vthe `:preferred embodiment of vthe invention by the provision of a pneumatic actuatorforeach dust val-veand segregating valve, the `actuators being controlled b y solenoid-operated valves, and by the provision of a novel electrical system for energizing the solenoids in proper sequence to empty the hoppers successively. The electrical system is largely dependent upon a special rotary sequence control switch, the operation of which is monitored by devices responsive to thevacuum `inthe 'system to Vassure that each dustvalve is ykept fopen the requisite tlme to empty the corresponding hopper.

As each hopper is emptied, kthe v'system will proceed tothe emptying ofthe next selected hopper.

The nature of the invention, `the advantages thereof, and the manner in whichthe variousobjectives are realized may be betterI understood by referring to the description Vherein `'of the Vpre'- ferred embodiment of the invention.

Referring to the drawings, Fig. 1 is a yschematic diagram of a 'dust handling system `in accordance with the invention;

Fig; 2 is an elevation View of 1an Aelectrically controlled pneumatically operated dust valve;

Fig. y3 is a longitudinal section of an'automatic materials handling controlled switch.

'Figl is a detailof the same.

Fig. 5 is a partial cross-'sectional view taken on,

thel plane indicated by the line 54-15 finFigf3;

Fig. 6 is a partial cross-sectional View taken on the plane indicated vby the line 6&5 in vl'lig. 3; and

Figs. 7 and s taken together ensititte 'a wiring 'diagram of the system.

General desem-pride Referring to Fig. 1, the system is adapted for the removal of dust from 'a plurality 'of hoppers Il. A dust valve I2 lbelow each h'opper isconnected byco'nduits 13 to Vone of tvvosegr'egating` Valves l5; 'the segregating valvesbeing connected by a conduit I6 to a dustY collector l-'l which lmay be of la wellfknowntype' in which `the dust is separated centrifugally from 'the air and falls into a hopper i8. Flow ofi'air through-the vsystemris preferably induced by an aspirator 19 actuated by a streamof water under .pressure supplied through a'conduit 20 and valve 2l, The aspiratoriwithdraws air lfrom the system through la line 22 connected to `the separator 'and thus induces a vacuum in the dust handling pipes 'I3 and I6.

A branch vacuum line 23 runs to the control panel 24 where, as will be seen, the degree of vacuum in the system is employed to monitor the operation of the system.

The parts of the system described thus far may be las more fully described in the abovementioned application of Frank B. Allen, except that the dust valves are adapted for electropneumatic actuaton and the segregating valves are added. The dust valves l2 and the segregating valves i5 are provided with pneumatic operators which are e supplied through a compressed'air line 21. Electric power is supplied to the control panel through a line 28 from which it is distributed through conductors indicated generally at 29 to electrical control devices for the pneumatic valve operators. The nature of the instrumentalities incorporated in the control panel will be made apparent in the description of the operation of the system, taken in connection with the wiring diagram. 'Ilhe specific location of the various devices on or in the control panel is a matter of choice.

A system involving seven hoppers and two segregating valves is described herein. It will be apparent upon further consideration of the system that it is adapted for the operation of as many as 30 dust valves in many groups.

Before proceeding to detailed description of 'the system, certain of the mechanisms employed therein will be described as an aid to the understanding of the system.

Windswept dust valve The windswept dust valve preferably employed in the system and illustrated in Fig. 2 is generally similar to that disclosed in U. S. Patent No. 2,368,395 to Frank B. Allen. Electro-pneu- ;matic valve opening means is substituted for the 'which is connected the vacuum line I3 (Fig. 1)

through which the ash is exhausted.

The clack valve mounted within the chamber 43 comprises a door 4B normally seating against the inner end of the outlet connection 44 and suspended by a hinge 41 keyed to an operating shaft 48. i A pvot pin 49 passes through a clevised lug 59 adjacent the upper edge of the door and through the central portion of the hinge 41. A second pivot pin I tted in the lower end of the arm 41 passes througha hole 52 in a lug projecting from the center of the door, the hole 52 being sufficiently large to a'ord a considerable amount of free travel to the pin 5I. Normally the door 46 tends to remain closed under the influence of vacuum in the outlet connection, but it may be opened when desired by rotation of the shaft 48, whereupon air is drawn into the valve through a pipe 89 mounted in an adapter 9| and passing below a partition 92 which partially separates the 'chambers 42 and 43. The ash will be drawn out of the chamber 42 along with the air. A pipe T 93 nippled to the adapter provides for the installa-tion of a low pressure air supply line 94 which may be desirable in applications of the dust valve to precipitator hoppers, or the installation of a check valve (not shown) on a nipple 95. The check valve is installed so as to ad- 4 mit air to the pipe 89 and chamber 43 when a vacuum exists within the chamber 43.

The mechanism for opening and closing the clack valve 4B comprises the shaft 148 which is journalled in the side Walls of the chamber 43 and extends into a crank housing 51 rlxed to the dust valve. The crank arm 58 keyed to the shaft 48 is connected to a piston 59 by connecting rod S0. Piston 59 Works in a cylinder 6| fitted in a recess in the housing. The cylinder is provided with a head 62. The cylinder, cylinder head, and

Vcrank arm housing are supported on a bracket 63 bolted to the body of the dust valve, the bracket being formed with a lateral extension 64 bored to iit around the cylinder 6l. Four studs 66 threaded into the housing 51 are tted with nuts 61 by means of which the cylinder head, cylinder and crank housing are compressively retained in assembled relation. Nuts 68, run up on two of the studs, engage the faces of the bracket 64 to locate and retain the entire assembly on the bracket. i

The piston 59 is urged downwardly in the cylinder by a spring 18 received in a seat 1l in the housing 51 and tted around the skirt 12 of the piston, which is of smaller diameter than the head. A cup leather 13 is retained on the lower face of the piston by a plate 14 and a machine screw 15. The cylinder is formed with a breather hole 16 near the upper end. Compressed air for the actuation of the piston 59 is supplied from the line 21 through a two-way solenoid-operated valve 11. Since valves of the type illustrated here are well-known articles of commerce, the valve will not be described in detail. A solenoid mounted within the'cap 18 at the top of the valve operates, through suitable linkage, valves which alternately close off the inlet connection 19 or'the vent connection 80, the vent connection being opened when the solenoid is deenergized and the inlet connection 21 being open when the solenoid is energized. The delivery connection 8| is a1- ways open. Thus, upon energization of the solenoid, compressed air passes through the open inlet 19, the delivery connection 8l, and piping 82 to the inlet 83 in the cylinder head, driving the piston upward. Air compressed above the piston is vented through the opening 18. As the piston ascends it rotates arm 58, shaft 48, and hinge 41 clockwise, drawing the valve door 46 from its seat. To close the valve 46, the solenoid is deenergized, shutting off the supply of compressed air and opening the vent connection 80. The spring 19 is thus able to force the piston down, exhausting the air below the piston through the pipe 82, valve 11, and pipe -85 into the interior of the housing 51.

Segregatz'ng :calves The segregating valves l5 (Fig. 1) are not illustrated in detail, since they may be of the same type of construction, insofar as the valve and its operating mechanism are concerned, as the dust valve. The body of the valve will, of course, be simply such as is adapted to mounting in a dust conduit. It may be noted at this point that, insofar as the overall system is concerned, the dust valves and segregating valves may be of any suitable form and the :actuator for the valves may be of any suitable type adapted for electrical control. The electrical control is an important feature in realizing the advantages of the invention, but may be employed through various instrumentalities at the valves, such, for example, as

individual electric motors.

L5 The automatic :material handling' control .switch This switch, illustrated in Figs. 3 to u6, is an importantelementl of rthe invention and has been developed to make-possible therealization of the advantages implicit in the 'conceptionof the sys` tem. Thisswitch effectsthe sequential actuation of the various-elements`of -the system and isparticularly adapted for control Lof the `progress of the operation under the supervisory 'action of -devices responsive to ther-vacuum .inthe system.

The switch is designed l.for :readyadaptation to ash handling installations of different .characteristics by Varying Vthenumloerand rform ofthe `cams and installationof various switch ccombinations.

The control switch of vamotor-,driven type, :provided with .a number of.cams mounted -Ona central shaftfor-operation offlXed switches to control .the dust and segregating valves and providepart of .the control for theswitch motor.

A second camshaft driven at a higher speed also is instrumental inY controlling the operation ofthe motor.

All theparts of the control vswitch |00 (Fig. 3)

are supported bye, switchbase |0|, formed with a generally .flat rearface whichmay bemounted against .the front of the controlpanel 24. A cupshaped switchframe |02 mounts the fixedswitches and supports the camshaft. The frameis formed witha flange Y| 03 extending around most of its vopen end, which isgsecured by cap screws |0311 (Fig. 6) to the base IUI. A pilotlll (Fig. 3) 0n vthe base `isreceivedin a counterbore in the frame to insure `exactalignment ofthe twoparts. The low speed camshaft |06 is journalled in a bushing |01 in the Vend ,of the frame and in a bushing |08 fitted inl a coverplate |09 secured tothe front of the base plate by machine screws, one of which is identifiedat ||0. The high` speed camshaft which is hollow and surrounds the reduced intermediateportion of the camshaft |06, is journalled ina bushingnl l2 `fitted inthe base |0| and journalled on a bushing ||3 retained between a, flange ||4 on the slow speed camshaft anda flange I l5 at the rear end ofthe high speed camshaft. The camshafts are restrained against axial movementl by the bushing |I3, a collar H6 secured to the camshaft by -a setscrew and engaging the inner face of the bushing ||2, and a collar ||1 secured to the `camshaft |06 .by a setscrew and engaging the inner face of the bushing |01.

The Vangular yposition of .the camshaft |06 is indicated by an assembly comprising an indicator ,75

wheel |34 clamped on the reduced front endof the shaft-by a nut |36. Light fromfan annular light )source |31 'mounted on the front of .the cover plate|09 passes through an opening k|38in thejindicator plate andilluminates a translucent dial 13S-fixed inthe cover plate. Numbers from 4one to thirty .are equally spaced about the periphery of the dial |39 in position to be designated bythe light passing through the opening |38.

lFour radial cams |4|, |42, |43, and 544 .are mounted on the high speed shaft .between the flange ||5 and a collar |45 screwed onto the shaft. The cams are held against rotation'relative to the shaft'by a key |46, and the collar by a washer |41 engaged in the keyway and provided with `a tab which may be bent down into a groove in thethreaded collar. These cams, as will be described-later, control the operation of the motor |20 .soethat itedrivesthe shaft through 1 80de- .grecs and the shaft |06 throughsix degrees at each operation of the motor.

Anumber of radial cams suited to the particular installation are mounted on the shaft |06. The design illustrated herein is adapted for the fitting of thirteen cams or any lesser number. For purposes of illustration, it may be assumed that cams |5I, |52, |53, and |54 actuate boiler selector limit switches, cams |6|, |62, |63,'and |64 actuate segregating valve operating switches, cams |1| and |12 operate starting and homing switches for the motor, and cam operates the dust Valve solenoids. The purposes of these switches, and their timing, will be described later.

The cams are. retained on the shaft 06 between the'ange ||4 and a threaded collar |48 and are located angularly by a key |49. A spacer |55 equal in width to one ycam is interposed between the cams |12 and |80 to provide needed clearance. A spacer |56, the length of which is determined by the number of cams mounted on the shaft, is disposed between the cams |64 and |1| to locate cam |80 in its proper position at the `end of the shaft.

The cam-operated switches are mounted as follows: The upper portion ofthe switch frame |02 is of considerable thickness (Figs. 3 and 6), and is milled to provide ve longitudinal fins `|51 with `switch-receiving slots lbetween the hns. The slots are spaced at an angle of twelve degrees with respect to the shafts. The entire periphery of the frame |02 at its rear end circumjacent the cam |00 is of added thickness, and is formed with a total of thirty uns |51 and slots |50, spaced at an angle of twelve degrees. The earn |80 mayactuate any number of switches-up to thirty, fourswitches |50 being shown `in posiltion in Fig. 5.

All the switches |59 are of similar construction throughout the device except that someare normally open, some are normally closed, and some are double-throw. They are of a type which iswellknown commercially comprising a rectangular body containing the circuit maker and breaker and having an actuating plunger |66 extending from the body. These plungers eX- tend through holes |:61a drilledradlally through the frame intopositionrto .be actuated by theriser ofthe corresponding zcam, such as cam |00 in Fig. 5. The switchesare held -in place by machine screws |61 and washersl of insulatingmaterial `bearing against the outer surface of the switches. In the embodiment described hereinfcam |80fis the only one which operates more than one fswitch, Theswitches operatedby the other .cams

are mounted in the four slots |58 in the top of the frame |02, the provision of four slots permitting a staggered mounting of the switches to provide the necessary longitudinal clearance. Each cam is formed with a riser such as (Fig. 5) or |13 (Fig. 6), the length of the riser being adapted to the characteristics of the dust handling system and the function the particular cam plays in the system. A terminal and fuse block |14 for the motor (Fig. 6) and a terminal block |15 for the dial light may be mounted on the' sides of the frame |02. The leads to the motor and light are led through bushings |16 in the upper portion of the base |0|. Leads from the various switches |59 and from the motor and dial light terminal blocks are connected to the circuits external to the switch through an assembly including a .switch connector plate |32 (Fig. 3) and a remote connector plate |33. The switch connector plate |82 is secured to the rear end of the frame |02 by studs |813 threaded into bosses |85 extending fromthe frame. The outer ends of the studs |84 are cylindrical and serve to locate the remote connector plate |33 with respect to the switch -connector plate. The leads from within the switch are connected to hexagon headed terminal bolts |86 (Fig. 4) which are retained in the plate |82 by nuts |81 and are provided with second nuts |83 to hold the wire terminals, The external wiring is connected to terminal bolts |89 in the plate |83, held by the nut |93 which secures the terminal in the plate |83 and a second nut |9|. A connector strip |92 is retained under the head of the terminal |89 in position to engage the head of the corresponding terminal |86 when 1 the two terminal plates are in juxtaposition. -Connector screws ISR passing through holes in the strips |92 are adapted for engagement in tapped holes |95 in the heads 0f the terminals |86. The heads of the screws |94 are disposed within recessed bores |95 in the plate |83 so that they are prevented from falling out of the plate |83. When the external and internal connections have been made, it is only necessary to slip the plate |83 over the studs |84, which may be so located as to determine uniquely the angular position of the plate |33, and then tighten the screws |34. A switch cover |91, consisting of a cylinder of sheet material or the like, adapted to protect the internal wiring of the switch, is slipped over the plate |82 and against a shoulder |98 on the switch base before 'the external connection plate |83 is assembled onto the switch.

Miscellaneous apparatus The system also includes a number of devices principally mounted in the control panel, such as manual switches, relays, indicator lights, a time delay switch, and vacuum operated switches. Since these devices are well known and commercially available, and no claim is made to the specific structure of these elements, they will be mentioned only in connection with the description of the operation of the system.

Electrical circuits and operation of the system The operation of the system will be described with reference to the schematic diagram of Fig. 1 and the wiring diagram of Figs. 7 and 8. Referring to the wiring diagrams, Fig. 8 shows the automatic sequence control switch |00, and, at the right, the dust valve and segregating valve operating solenoids. Fig. 7 shows all the devices on the control panel except the switch |00. Power for thefoperation of the system is fed 8 through conductors 28 to a main power switch 200 which remains closed when closed manually and may, of course, incorporate overload circuit breakers or fuses. The main switch 200 energizes conductors 20| and 202 which may be considered as supply and return conductors for the various units of the system. In tracing circuits herein, unless otherwise specied, they will be traced from the supply conductor 20| to the return conductor 202 and conductors 20| and 202 will not be mentioned, in order to avoid prolixity. In addition to electric power, the system must be supplied with compressed air through line 21 to operate the valves, and with water through pipe 20 to produce the vacuum.

The ash hoppers ordinarily may be divided into groups, and means are provided by which the hoppers of any or all groups may be emptied. The seleetion'of groups is eiected by boiler group control units such as 2 l0 and 3 0, shown set off by dotted lines in Fig. '1.

In order to avoid unnecessary complexity, the wiring diagram shows a system involving only two boiler groups with three dust valves in each group, a seventh dust valve not in either group, and two segregating valves. As will be apparent from the description of the system, it may readily be expanded to handle more and larger groups of dust valves and more segregating valves. The principles of the larger system are the same as those of the small system of which the wiring diagram is shown.

A group control units 2|0, 3|0 is installed on the control panel for each boiler group in the system. Since these units are identical only one will be described in detail. When the main contactor 200 is closed and vacuum has been established, assuming the operator wishes to empty the hoppers of boiler group one, he moves group control switch 2|| to its-on position. This switch will remain in either circuit-closing position. When moved to the on position the switch 2|| completes a circuit through its contacts 212, conductor 2|3, group control relay coil 2 i4, and conductor 2 5. The relay opens its back contact 2 I6 extinguishing the Boiler Group Oi, signal light 2|1. The relay also closes its front contact 2 I9, energizing the Boiler Group On, indicator light 220. Thus, by the indicator lights 2|1 and 220 and corresponding indicators in the other group control units, the attendant can readily see which groups have been cut in. Normally, the system is set up for automatic operation by means of the manual-automatic switch 350, the contact member of which may be locked in engagement with its automatic contacts 35| to prepare circuits which will be described presently. With the boiler group selection established and the system set up for automatic operation, the operation is initiated by closing the Start push button switch 360. This energizes the Vcircuit holding relay 310 by a, circuit through the switch contacts 36 wire 362,`re1ay coil 310, wire 363, and switch 21| operated by thecam l, the switch 21| being closed when the control switch |08 is in its starting position. Relay 310 closes its front contact 31|, shunting the starting switch 360, and thus holding the relay energized, through

wires

312, 362, and 363 and switch 21|. The System Energized indicator light 315 is energized through contact 31| and wires 312 and 313.

At this time none of the dust valves or segregating valves is open, and the first operation performed by thecontrol switch |00 is to open the group onesegregatingvalve andnumer one'dust valve. Sincev the valves should not be opened unless thei` proper amount of vacuum is present, the.` operation of the motor: |20 to causeopening of anydust valve'v is under control of a Vacuum l-Iigl''switchv 380, which is actuated by a pressure responsive device (not shown)v connectedto the vacuum line 23 (Fig. 1) so as to close its contacts38| whenever'the degree of vacuum in the system is such-as normally should obtain with the aspirator I9'y in operation and all the dust valves closed. On closing of the vacuum high switch conta-cts 38|, a circuit is closed through wire 382, contact 24.1', which isyheld closed by the cam |4| whenthe control switch |00 is in its starting position, wire 31.6, a normally closed switch 500, wire 31:1, front" contact 310 of relay 310;- and'wire 319i to themotor. |20. The motor thus begins to operate and drives the cam |80 at low speed', the cam lift movingtoward the plunger of the switch 28| controlling the solenoid 29| vof dust valve No. 1. The motor also drives cam |6| toward` theposition inv which it operates switch 26|.' to energize' the solenoid 30|` of segregating valve number one which controls the flow of materialkfrom dustvalve number one. Before the solenoids-29fl" and' 30| are energized, the cam |42 on.4 the high speed' shaft closes its contact 242.

Thisl contact, which closes' after 15 rotation of the high speed camshaft and remains closed until 180' degrees rotation' is completed is provided to insure that the motor drives the cam shaft |`||1 through al full'half turn and the cam shaft |06 through: six degrees, although the vacuum drops oi asthe'vvalves are opened. Switch 242 simply shuntsthe vacuum high switch, providing a circuit' through switch 242, wire 316, switch 500, wire 311,' contact 318, and wire 319` to the motor. Subsequent to the closing of switch 242, switch 24| opens under rotation of the cam, and after 180 degrees rotation of the cam shaft I'I'l, contact 242 opens, d'eenergizing the motor.

wires

263 and 264 to a Segregating Valve Number One Open indicator light 222. At the same time, switch 26| extinguishes a Segregating Valve Number One Closed indicator light 223 which is energized through the normally closed contact of switch 26| and wire 235. The indicator lights 222 and 223, and similar indicator lights of the other groups, show at all times the open or closed condition ofthe segreu gating valves. The energizing circuit for all the dust valves in group number one is prepared by front contact 224 of group number one control relay 2|4 wheneverl that group is selected. The circuit' is throughcontact 224 and wire 225 to the individual'switches 28|', 282, and 283 which control the groupy one dust valve solenoids. Thus, when the lift of' cam |80 closes the first switch 28 I', solenoid 29 |Y is'energized'. With the system in this condition, the ash isdrawn from number one hopper through thei number one dust valve 2, Fig. l, pipesv E`3 segregating valve l5 and pipe `|6 into-the separator l1; As'long as the hopper contai'ns ash which is being transported by the system, a considerable-vacuum will be present in the system and' in the'li'ne' 23'.

However, when the hopperv has been emptied uum is broken, the contacts'l ofthe switch are closed. However, inasmuchy asa temporary low vacuum condition# might. result from momentary arching ofV the` material in thefhopper, la time delay device; 4100 is. installed to prevent closing of the dust valves unless the low vacuum condition persists for apredetermined time. The timer 400 is of' a well-known type comprising an electric motor 40|v which, through suitable mechanism, closes a-normally open contact 402 after a pre'- set period of operation. A desirable timerange for this system is from two to thirty seconds, and the timer-maybe' set to any desired delay within this range onavbasis of experience in the operation ofV a particular installation. The vacuum low switch closes the circuit' throughy its contacty 30|', wire 392, time delay motor 40|, wire 393, and a normally closed switch 50|. period of operation, the motor 40| completes a circuit"` through contact 35|' of the manual-automatic switch', wires' 352' and353', contact 402, wire 403, switch 2.43 closed by theI rotary switch cam |43', wire 31'6,

switch

500,1 wire1311, contact: 318,

and wire 313' to the motor |20. The contact 243r is closed' bvI the rotary/switch shortly before the completion of the rst degrees rotation of the camshaft l', and'remainsy closed until after switch 244 is closed by the cam |44 at.V 195 .degrecs rotation from the starting point. Timer switch 402 and cam switch 243.thus initiate operation off the motonand switch 244 maintains the motor in operation, regardless of the vacuum condition ofI the system, until the completion of 360 degrees rotationV of the high.`Y speed cam shaft.A The motor is energized through switch 244, wire 3113 andthe remainder of the circuit just traced; the switchA 244 shunting the manual-automatic switch and timer switch. Switch 244 opens after 360 degrees'rotat'ion, at which time switch 24| has been closed; preparing the previously traced circuit through the vacuum high switch for the next cycle of 'operation'.

As the motor rotatesv the highl speed cam shaft through its second half turn' the low speed cam shaft is rotated from its 6. degree to its 12 degree position and' cam |80 opens switch 28|, deenergizing solenoid 29| f and causing the closing of the number one dust' valve. When the dust valve closes, the vacuum in the system increases and the vacuum high switch initiates operation of the motor to open dust valve number two by the action-.of cam |801, switch` 282', and solenoid '292. The operation thus continues: until` all the hoppers of group one have been emptied. As the final solenoid 293 of' group one isi deenergized, completing the emptying of a-ll the hoppers tribu-` tary to the numberfone segregating valve, cam |6| releases switch 26|f, deenergizing solenoid 30|, closing the segregating valve extinguishing the valve open indicator'lightf222", and energizing the valvel closed light 223.

The segregatingvalve circuits pass only' through the cam-operated switchesV 26| and 262, and thus the segregating valves are opened in succession asl the cam shaft |06 proceeds throughy dust valves' of they groupfwill remain closed andthere-V will be no loss. of vacuum in theV system. Unless means werer provided to cause the motor to; operate through thei positions of the low speedi After its preset.`

cam shaft corresponding to that group, the motor would remain deenergized, after completing the first half cycle of rotation of the high speed cam shaft after entering the group. In order to operate the motor through an unselected boiler group the selector switch 2l I in its off position closes a circuit through its contacts 2319, wire 23|, boiler group limit switch 251, wire 253, wire 319 and motor |20. The limit switch 25| is held closed by the cam |5| on the low speed shaft during that portion of its rotation which corresponds to the opening of the individual dust valves of group one.

After the completion of group one, the control switch cam |86, as soon as vacuum is restored to the system, is operated to close switch 284 and energize solenoid 294 to open the fourth dust valve. It should be noted that this valve is not a member of either group and the energizing circuit for the solenoid proceeds directly from the supply line 20| through the switch 28d. This valve will thus be opened regardless of the position of the group controls. Valve number four illustrates the manner in which a valve may be made independent of the group controls if it is desired that the valve be opened during each ash removing cycle. Assuming that number four hopper is in the pipe grouping of the second segregating valve it is necessary for this valve to open as the dust valve opens. Therefore, at this time switch 262 is operated by cam |62 to energize the solenoid 302 of the second segregating valve through wire 266.

When the number four hopper is emptied, the motor will proceed as before, under the control of the vacuum low and time delay switches to deenergize solenoid 294 and proceed with the energization of

solenoids

285, 296, `and 291 which actuate the dust valves of group number two. If the group two control switch 3|! is in its on position, the setup for group two is identical to that for group one, and therefore it is unnecessary to describe the operation. The limit switch 252 completesv a circuit to run the motor and cam shaft through group two in case that group is not selected, acting in the same manner as switch 25| of group one. Obviously, additional groups may be taken care of by the system by the utilization of additional cams in the switch |00, which, as illustrated in Fig. 3, is provided with suflicient cams for the operation of four groups. Any desired number of dust valves may be included in each group and the total number of dust valves, with the switch as shown in Fig. 3, may be any number up to 30. The length and position of the lifts of the cams on the low speed shaft must be adapted to operate the segregating valves and the limit switches 25| and 252 during that portion of rotation of the cam shaft in which the dust valves belonging to the particular group are actuated.

When the switch reaches the position corresponding to closing of the last material handling valve, which in the illustrated system with seven valves would be after 84 degrees rotation of the main camshaft, cam |12 closes the homing switch 212, energizing the motor directly through switch 212 and wires 253 and 319 to return the main :camshaft to its zero position, at which point the switch 212 is opened by the cam. After switch 212 closes, the normally closed switch 21| is opened by the cam 1|, breaking the holding circuit for the relay 310, which dropsl out. Switch 21| is closed shortly before the low speed camshaft reaches its zero position,

preparing the holding` circuit for relay 310 through wire 363. However, the circuit is open at contact 31| of the relay. As the main camshaft is returned to its starting position, switch 212 opens, deenergizing the motor and leaving the system in condition to be restarted when desired by actuation of the Start push button 360.

In the event of a power failure during the operation of the system, all the valve solenoids will be deenergized and the valves will close. The control switch will remain in whatever position it was in at the time of the power failure. When the supply of power is reestablished, the valves are reopened, but in order to start the motor it will be necessary to operate the Start button 350 to reenergize the relay 31D. yThis condition will be indicated by the fact that the indicator light315 will remain extinguished until the system is restarted. When the Start button is operated the system will resume operation and complete its cycle.

If either the vacuum high switch 38D or the vacuum low switch 39B should fail to operate during the cycle the operation of the control switch will be interrupted. In order to restart the control switch the attendant may operate a Jog'switch 4|!) which is a normally open twoway push button switch. When the switch button is depressed, it closes contacts 4H which shunt the vacuum high switch 38| through wire M3; and when the Jog switch button is pulled, it closes contacts 4|2 which shunt the time delay switch contactl 402 through wires- 353 and 4M.

In case manual rather than automatic operation of the system is desired, the manual-automatic switch 350 is' unlocked, opening the circuit which intiates operation of the motor |20 to close the dust valves at contacts 35|. With the switch 35| open the motor |20 will operate automatically only to open a'valve. In order to close the valve, the attendant must depress the button 356, closing its Manual contacts 355 and thus completing a circuit through wires 356, M4 and 4113 to the contact 243 of the control Switch through which the motor is energized for the valve-closing portions of the cycle. In manual operation, therefore, the attendant may watch a vacuum gauge installed on the control panel and press the button 350 as the gauge indicates, by loss of vacuum, the emptying of each hopper.

If the operator desires to terminate the operation of the system at any point in the cycle during automatic operation, it is only necessary to put all the group control switches, such as 2H and 3| l, in the off position. In this case, no additional valves will be opened, and the motor will run the control switch back to its starting position, being energized through the limit switches 25| and 252 and the homing switch 212. The operator may also skip certain dust valves in a particular group if he desires by watching the control switch dial which indicates the progress of the operation. Just before the motor reaches the point at which it would operate to open the valve or valves which it isdesred to skip, the attendant turns the corresponding group selector switch to the off position. The motor will then proceed under the control of the boiler limit switch. As it reaches a position to open the next dust valve which the attendant desires to operate, he may return the group control switch to its on position causing the resumption of the operation of the dust valves.

The dial light |31 is energized through a transals-14,33%

I3 formertiZil supplied from the conductors 20l and 22 so that the dial is illuminated whenever the main contacter 20E] is closed.

The type of motor which is considered most suitable for driving the control switch is energized through an external capacitor and resistor, which may be mounted within theupper part of the cover plate H19 (Fig. 3) and which have been omitted from the drawings to simplify the same. Obviously, any self-starting motor having relatively constant speed characteristics may be `used to drive the switch.

The switches 59H and 50! (Fig. 7) are provided only in case the system utilizes a dust separator Il of a type that is provided with a dump gate for discharging the ash. With a, col-- lector of this type the vacuum is broken when the dump gates are opened with the result that the motor i 2B would be energized by the vacuum low switch and might close a d-ust valve of a hopper which had not been emptied. To provent this, switches 5530 and 50i are opened by the dump gate control. Whenever` the gate is opened, switch 5m opens the circuit of the time delay motor Lll, preventing its operation by the vacuum low switch, and switch li opens the motor circuit, preventing it from being operated except by the boiler limit switches 25! and 1352 andthe homing switch 212.

Summary 'It will be seen that the system as described provides for the automatic emptying of the ash hoppers of any or all groups. Once the operation is initiated, the mechanism will proceed automatically with the operation and shut itself olf when the job is finished. The system performs a sequence of operations under a form of control which assures the completion of each operation, specically, the emptying of each ash hopper, and which upon completion of each'individual operation immediately proceeds with the next succeeding operation. The system is also adapted for non-automatic operation under the supervision of' an attendant. It is safeguarded against faulty operation resulting from power failures.

From the practical standpoint the system. disclosed herein has many advantages over previ'- ously known control systems for ash handling installations. The ash hoppers in boiler stations are often in locations which are relatively inaccessible. With the preferred-'type of dust Valve actuator shown herein, it is only necessary to run a compressed air line and' an electrical conduit to each hopper. Thus, shafting for the operation of the dust-valves is eliminated. Another advantage of individual actuators for the dust valves is that it no longer necessary to operate all of a number of dust' valves connected to a common opening device in order to empty one hopper.

The actuating cylinders for the valves are simple, substantially trouble-.free and easily maintained if necessary. The same is' true'ofl the solenoid-operated valves which are tried and proven items used in many applications. The elements of the electrical system,- with the exception of the rotary control switch, are readilyobtainable articles of commerce which are easily understood and do not require skilled' personnel for maintenance, replacement or repair. The rotary control switch is a special unit but is of a particularly fool proof construction andi inherently of4 great reliability. Y

The control' system of the invention was'eonceived in response to the need for a better solution of theproblem of handling material and the embodiment of this system chosen for illustration thereof is an ash handling installation. However, it will be apparent that the system is essentially one for the automatic control of operations in a process which is so constituted as to be responsive to the progress of the operations and thus to allow the needed' time for each operation and to carry out the operations in proper sequence without unnecessary delay between operations. Therefore, the control system as such should not be regarded as particularly an ash handling system, since many applications to other processes are within the natural field of the control system. In applications other than that described herein, the circuit through which the operation of the switch motor is initiated may be controlled. by any suitable condition which indicates the progress of the operations under control by the switch.

Although theforegoing description is necessarily of a detailed character, inv order that the invention may be completely set forth, it is to be understood that the specic terminology is not intended to be restrictive orv conning, and that various rearrangements of' parts and modifications of detail may be resorted to without departing from the scope or spirit of the invention as herein claimed.

One modification which is contemplated is to locate the solenoid-operated valves for the control of the dust valves and segregating valves at a central point, whichv may be the control cabinet. This would not necessarily entail any modification in the manner` of operation of this system, the only significant difference being in the location of elements of the system. In otherA words, instead ofrunning wires from the control cabinet to solenoids mounted on the dust and segregating valves, air lines would -be run from the'control cabinet to the valves.

What is claimedy is:

1. A system for handling dust comprising a plurality of dust collecting chambers, a dust receiver, a conduit connectingeach collecting chamber with the receiver, means to create a vacuum in` the receiver, and a normally closed valve between each collectingv chamber and the conduit, whereby upon opening the valve gas and dust may be drawn from the collecting chamber into the conduits and thence into the receiver by vacuum, characterized by means for opening the valves comprising an energizable actuator forl eachl valve, a separate electrically-operated control device for each actuator, andmeans for selectivelyy energizing thev control" devices.

21 A system for removing dust from a plurality of dust collecting chambers comprising a dust receiver, a cond-uit connecting each collecting chamber with the receiver, means tol create a vacuum in the receiver, and a normally closed valve between each collecting chamber and the conduit, whereby-upon opening the valve gas and dust may be drawn from the collecting chamber into the conduitsI and thence into the receiver by vacuum characterized by automatic means for sequentially opening. the valves comprising a separate energizabl'e actuator for each valve.

3.- A system for handling dust comprising a plurality of dust collecting chambers, a dust and gas separating chamber, a. conduitv connecting each collecting chamber with they separating chamber; means to create. a vacuum in the. separating chamber, and a normally closed vvalve between each collecting chamber and the conduit, whereby upon opening the valve gas and dust may be drawn from the collecting chamber into the conduits by vacuum, characterized by automatic means for sequentially opening the valves comprising a separate energizable actuator for each valve. e

4. A system for handling dust comprising a plurality of dust collecting chambers, a dust receiver, a` conduit connecting each collecting chamber with the receiver, means to create a vacuum in the receiver, and a normally closed dust valve between each collecting chamber and the conduit, whereby upon opening the valve gas and dust may be drawn from the collecting chamber into the conduits and thence into the receiver by vacuum, characterized by segregating valves each adapted to isolate certain of the dust valves from the receiver, means for selectively opening the dust valves, and means for opening the segregating valve corresponding to the selected dust valve when the dust valve is opened.

5. A system for handling dust comprising a plurality of dust collecting chambers, a dust and gas separating chamber, a conduit connecting each collecting chamber With the separating chamber, means to create a vacuum in the separating chamber, and a normally closed valve between each collecting chamber and the conduit, whereby upon opening the valve gas and dust may be drawn from the collecting chamber into the conduit by vacuum, characterized by a separate actuator for each valve, and means for progressively energizing the actuators comprising means sensitive to a predetermined vacuum in the conduit to initiate action of the energizing means to cause opening of each valve, and means responsive to a predetermined lesser degree of vacuum to initiate action of the energizing means to cause closing of each valve.

6. A system for handling dust comprising a plurality of dust collecting chambers, a dust and gas separating chamber, a conduit connecting each collecting chamber with the separating chamber, means to create a vacuum in the separating chamber, and a normally closed valve between each collecting chamber and the conduit, whereby upon opening the valve gas and dust may be drawn from the collecting chamber into the conduit by vacuum, characterized by a separate actuator for each valve, and means for progressively energizing the actuators comprising means sensitive to a predetermined vacuum in the conduit to initiate action of the energizing means to cause opening of each valve, and means responsive to continuation for a predetermined interval of a predetermined lesser degree of vacuum to initiate action of the energizing means to cause closing of each valve.

7. A system for handling dust comprising a plurality of dust collecting chambers, a dust rand gas separating chamber, a conduit connecting each collecting chamber with the separating chamber, means to create a vacuum in the separating chamber, and-a normally closed valve between each collecting chamber and the conduit, whereby upon opening the valve gas and dust may be drawn from the collecting chamber into the conduits by vacuum, characterized by a separate actuator for each valve, means for progressively energizing the actuators, and means for preventing energization of selected actuators.

. 8. A system for handling dust comprising a plurality of dust collecting chambers, a dustand gas separating chamber, a conduit connecting each `collecting chamber with the separating chamber, means to create a vacuum in the separating chamber, and a normally closed valve between each collecting chamber and the conduit, whereby upon opening the valve gas and dust may be drawn from the collecting chamber into the conduits by vacuum, characterized by a separate actuator for each valve, means for progressively energizing the actuators, means responsive to relatively high vacuum in the separating chamber to initiate operation of the energizing means to open a valve, and means responsive to relatively low vacuum in the separating chamber to initiate operation of the energizing means to close a valve.

9. A system for handling dust V.comprising a plurality o dust collecting chambers, a dust and gas separating chamber, a conduit connecting each collecting chamber with the separating chamber, means to create a vacuum in the separating chamber, and a normally closed valve between each collecting chamber and the conduit, Wherebyupon opening the valve gas and dust may be drawn from the collecting chamber into the conduits by vacuum, characterized by a separate actuator for each valve, means for progressively energizing the actuators, means responsive to relatively high vacuum in the separating chamber to initiate operation of the energizing means to open a valve, a settable timedelay device to initiate operation of the energizing means to close a valve, and means responsive to relatively low vacuum in the separating chams ber to initiate operation of the time-delay device.

l0. A system for handling dust comprising a plurality of dust collecting chambers, a dust receiver to which the dust is transported from the chambers, means for creating a vacuum in the receiver, a number of normally closed segregating valves, conduits connecting the segregating valves to the receiver, a normally closed dust valve communicating with each collecting chamber, conduits connecting the dust valves to the several segregating valves, the dust valves connected to each segregating valve constituting a group, and means for sequentially opening the dust valves of any selected group including means responsive to' an empty condition of the collecting chamber for effecting closing of the corresponding dust valve and means responsive to the closing of the dust valve for effecting opening of the next dust valve in the sequence.

1l. A system for handling dust comprising a plurality of dust collecting chambers, a dust receiver to which the dust is transported from the chambers, means for creating a vac-uum in the receiver, a number of normally closed segregating valves, conduits connecting the segregating valves to the receiver, a normally lclosed dust valve communicating with each collecting chamber, conduits connecting the dust valves to the several segregating valves, the dust valves connected to each segregating valve constituting a group, means for sequentially opening the dust valves of any selected group including means responsive to an empty condition of the collecting chamber for effecting closing of the corresponding dust valve and means responsive to the clos- V ing of the dust valve for eiecting opening of the next dust valve in the sequence, and means for maintaining the segregating valve of the group open during the periods of operation of the dust valves of the group.

12. A system for handling dust comprising a plurality of dust collecting chambers, a dust receiver to which the dust is transported from the chambers, means for creating a vacuum in the receiver, a number of normally closed segregating valves, conduits connecting the segregating valves to the receiver, a normally closed dust valve communicating with each collecting chamber, conduits connecting the dust Valves to the several segregating valves, the dust valves connected to each segregating valve constituting a group, means for sequentially opening the segregating valves, and means for sequentially opening the dust valves of any selected group including means responsive to an empty condition of the collecting chamber for effecting closing of the corresponding dust valve and means responsive to the closing of the dust valve for effecting opening of the next dust valve in the sequence.

13. A System for handling dust comprising a plurality of dust collecting chambers, a dust receiver to which the dust is transported from the chambers, means for creating a vacuum in the receiver, a number of normally closed segregating Valves, conduits connecting the segregating valves to the receiver, a normally closed dust valve communicating with each collecting chamber, conduits connecting the dust valves to the several segregating valves, the dust valves connected to each segregating valve constituting a group, means for sequentially opening the segregating valves, and means for sequentially opening the dust valves of any selected group includ- -ing means responsive to the vacuum condition of the receiver for effecting closing of the open dust valve and vacuum-sensitive means responsive to the closing of the dust valve for effecting opening of the next dust valve in the sequence.

14. A system for handling dust comprising a plurality of dust collecting chambers, a dust and gas separating chamber, a passage connecting each collecting chamber with the separating chamber, means to create a vacuum in the separating chamber, and a normally closed Valve between each collecting chamber and the passage, whereby upon opening the valve gas and dust may 4 be drawn from the collecting chamber into the passage by vacuum, characterized by a separate actuator for each valve, means for progressively energizing the actuators, means sensitive to a predetermined vacuum in the passage to initiate 18 action of the energizing means to cause opening of each valve, means for disconnecting the sensitive means immediately after initiating the valveopening cycle, and means for continuing the cycle to full open valve position` independent of the sensitive means.

15. A system for handling dust comprising a plurality of dust collecting chambers, a dust and gas separating chamber, a passage connecting each collecting chamber with the separating chamber, means to create a vacuum in the separating chamber, and a normally closed valve between each collecting chamber and the passage,

vwhereby upon opening the valve gas and dust may be drawn from the collecting chamber into the passage by vacuum, characterized by a separate actuator for each valve, means for progressively energizing the actuators, means sensitive to a predetermined vacuum in the passage to initiate action of the energizing means to cause opening of each valve, means for disconnecting the energizing means immediately after initiating the valve-opening cycle, means for continuing the cycle to full open valve position independent of the energizing means, means for connecting a second sensitive means responsive to a predetermined lesser degree of vacuum to the energizing means just prior to reaching the full open valve position, means for the second sensitive means subsequently to initiate the second part of the energizing means cycle for closing the valve, means for disconnecting the second sensitive means immediately after initiating the valve closing action, and means for continuing the cycle to full closed valve position.

LAURITZ E. MYLTING.

REFERENCES CITED The following references are of record in the i'ile of this patent:

UNITED STATES PATENTS Allen May 6, 1947