US1664229A - Drier-control system - Google Patents

Description

S. A. STAEGE DRIER CONTROL SYSTEM Filed July 23, 1925 March 27, 1928.

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ATTORNEY Patented Mar. 27, 1928.

UNITED STATES PATENT OFFICE,

STEPHEN A. STAEGE, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

DRIER-CONTROL SYSTEM.

Application filed July 23, 1925. Serial.No.-45,565.

My:;invention relates .to heating devices andparticu'larly to control means therefor.

An object of my inventionis to provide a motor-driven and drag-link-controlled means forefiect-ing the energization and de-energizationof a plurality of heating unitsin step-.byrstep sequence. I

Anotherobject of my inventionis to. provide ,a system normally controlled by a drag link.;to control the energization ofall of a plurality of heating units, and temperatureactuated means for controlling the step-bystep energization of a portion only bf the heating units In practicing myinvention,.l .provide a plurality-of heating units, the energization of which iscontrolled by a motor-actuated contact drum, the motorbeing vcontrolled by a drag. ;link pperativelyassociated with the material being dried. 7

A second contact drum is operatively associated withthe first conta ct drum and is adapted to control the operation-0f the motor. through a limited range of movement of thedrum, the operation thereof being controlled by a thermostat means.

In the single sheet of drawing,

Figure 1 is a View, in longitudinal vertical section, of a drier unit with which is associated .the system embodying my, invenme.

Fig. 2 is a diagrammatic view of circuits and apparatus embodying my invention, and

Fig. .3 is a fragmentary view illustrating the .dcvelopcd surfaces of contact drums comprising a part of my ,invention.

The'system embodying my invention is particularly adapted for usein connection with an electrical heating unit for drying initially wet webs of material, such as paper, and I have elected to illustrate and describe the same in connection with such a drying unit indicated generally by the numeral 11 in Fig. lot the drawing] 7 I -The heating unit comprises a substantially enclosed casing designated by the numeral 12 that may be of any suitable or desired type ofvconstruction, and which will be of suchcontour and dimensions as to permit of moving therethrough an initially wet .web of material 13.- Two of the walls of the casing 12 are provided respectively with an entering slot 14 and a-leaving slot 15 to permit of moving the webinto and out of the casing 12. '1' Y Means forl supporting the web 'otmaterial within thecasmg l2 and for moving' it there-f through in acircuitous path comprisesa" pluralityof superposed endless 'woven wire belts 16, 17,18 and 19. Each of the endless mesh, aresuppo'rtedjbytwo spaced rollers or drums 21 and 22 that are supported in woven wire belts, that are of relatively small 4 any suitable or desired'mann'e'r usually jemployed in the art.

The drums or rollers 21 may be so mounted as to be movable ina'horizontal plane relatively to, the-co-operating drujm122,'.in

order that ja uniform tension may be pr o vided for -the'respective endless belts sup The upper port-ion of each of the endless beltstravels over a plurality of smaller auxiliary roller members 23, the positions of these rollers, being such that the upper portion of a lower endless belt and the adjacentlower portion of the superposed endless belt,

are in close operative engagement and will receive the web or paper or ofmaterial. therebetwcen and cause it to be moved through the casing without wrinkling or welding of the paper during the drying operation to which itis subjected during its movement through the casing.

Meansifo r drying the initially wet web of mater al compr ses a plurality-of electric heating units, each comprising a suitable re fractory suport 24 and a resistor member 25 mounted thereon, the heating units being 10- cated in spaced relation relatively to each other and to the individual passes of the web of material during its movement through the casing.

The heating units are preferably uniforml v distributed, substantially as illustrated in Fig. 1 of the drawing, and are so energized that the temperature thereof will be rela- .7

tively high, that is, of the order of 1200 1 into a dry superheated vapor which, by reason of the substantially enclosed casing witlr in which it is generated, Will'be under a slight pressure relatively to the outside of the cjasliig,

The dry superheated vapor may be permittccl-t-o escape through a suitableexhaust conduit; 2 6 or it may; befconducted therethrough t'oiother. devices wherein the heat in thevap rm'a-y beiprofit abljy' employed. The

ercontage o f .fluid that, is transformed into r-y superheated vapor and therefore, the drynessof th l'eaving web Ofmaterial will, f'cou rse, be in accordance with the amount of energy to.- heat .within the eas- .ing and in accordance'with the amount of time whichit takes to, move the web through thefcasii gas well, as in accordance with the amount. of fi'uidf i'ni tially in the web.

The amount ofelectrieal energy transformed into heat within such casing is relatively large and is of the order of 75 kilowatts per-ton of daily capacity. of a. paper machine accordingly, for a hundred ton paper machine the amount of'energy translatedto heat will lie approximately 7500 kw. Itis very undesirable toenergi'ze' all of this capacity of heating units or to d e-energize the same atone. time. because of the injur ous eflcct upon. not only the generator and its prime mover, but more, particularly upon the ,\'ol'tage conditions in the network or line to: which it, is: connected. In order to flect a step-by-step energizatifon of the heating;.i1nit.s in such drier system, it is suitable to subdivide the heating units in order that they may he symmetrically located within the. casing. and to perlnit of their energizationin sequence through suitable circuit controllingmeans.

I have illustrated a plurality of resistor members .25 as-divided: into five groups of heating units directly controlled by five .t .Qtb,rs 27, 28, 29', 31 and 32, respectively, thatare. illustrated symmetrically only as comprising an actuating coil and cooperating contact members.

. lie energizati'on. of. the respective. actuating' 'coils ofthe contactors is controlled by a contact drum 33' that has mounted thereon an electric conducting contact plate 34, one edge. portion. of" which is provided with a recess 35 and the other edge portion thereof is 'of serrated form, substantially as illustrated. Fig, 3 of the drawing, whereby one edge is relatively short as compared to the other edge portion thereof. The drum 33 is mounted on a suitable shaft 36 and is of such construction that a plurality of resilient contact members 37, 38,. 39., 40, 41, 42, 43 and 44 may operatively engage either the electric-conducting surface 34 or the electric-insulating surface. 45.

Means; for effecting; rotation of the drum 33 and of the shaft 36 in either a forward or a reverse direction comprise a worm gear 46 that is engaged by a worm 47 which is, in turn, mounted on the armature shaft of a motor. 48 that has two field windings 49 and 51 that are wound in opposite directions or connected in such relation" that their alter native energization will effect an operation of the motor in opposite directions;

Means for effecting energizationof the motor and selective energizatin of the re spective field windings 49"and 51 comprise a' magnetic relay 52; Therel'ay 5.2compri'ses a double contact. lever 53 pivotallymounted' at" its non-conductingintermediate portionand actuated. by'an electromagnet comprising a core. member 54' and an energizing coil 55". A spring '56 biases the double contact lever to a predetermined position.

The energizationof the coil 55' is controlled by a. pivotally mounted draglink 57, the free end of which is normally inoperative engagement with the moving web of material 13; as illustrated more particularly in the lower right-hand portion of Fig. 2- of the drawing.

The position ofthe druin33 illustrated", isthat in which all'of-the contactors 27'to- 32, inclusive, are; closed, the drum having been turned in such direction that the brushes,

illustrated in Fig. 2 of the drawing, are inengagement with the wider portion of the contact plate 3.4, with the exception of the brush 38 that is located in the recess 35' of the contact plate. Energy is' supplied from two supply circuit conductors 58 and 59' to all of the heating units and to the control device. A circuit may be traced from conductor 58 through brush 37, the contact plate 34, brushes 40, 41, 42, 43 and 44, corresponding conductors to the actuating coils of the contactors 27 to 32, and thence through a. conductor 6'1 to supply circuit conductor 59;

In this position of the drum, all of the llu -inthe plzine'of tlie illustrated in which it connects two contact terminals 64 and 65, respectively connected to one terminal ofthe field magnet coil 51 and to the brush 38.

--:In-case of breakage-of the web of material, it is desirable to immediately de energize the heating units in'step-by-step sequence. Abr'eakage of the web 13permits the drag link 57 to-be disengaged-from the contact member 62,-causin'g deenergization of-the' coil 55' and-permitting a spring 56 to'move'thedouble arm-lever 53 to the position""illustrated by the broken lines in which the 'lett-hand conducting portion will ,be in operative engagement with two spaced"contactm'embers 66=and 67. The contact members A 66' and --67- are respectively connected-tdbr'u'sh 39 "and to the outer terminalfofffieldwinding=49,

" soon 'as the web breaks and the drag link dr'iips, causing de-energization of the coil -55'--'and consequent engagement of thelevr 5 3 jivith- 'the" -contaot members 66- and 67, -acircuit'{is' icompleted which may be "traced-*irom' supply circuit "conductor '58 through bru'h '37, contact-- plate 434,"- brush 39, contact; member 66, contact member 67,-

fieldwind-ir'ig 49, arrnature 48,-andthrough a conductor' -68 tothe supply circuit cond'uctor59.= -'I-he-motor then'rotates the drum imsuch direction that the; brushes will, in effect, be moved-=to- 'th= positions shown in Fig- 3"of'the drawingxthat "is, the surface of the drum will move downwardly paper as shown in Fig. 2 -of-the'drawing.- 5

Thebrush 44 will be the first to be disengaged fromflthe electric conducting plate 34, thereby de-energi'zing :the' coil "of: the 4 contactbr -32 and,* therefore, causing de-energiz'ationiof the group-of heating units con trolled therebyL-The brush 43 next engages the electric' insulating surtace: 45' and the coil of contactor.31 is-deenergized, The

: rotation of the drum'33 continues until the brush 39, connected to the contact member 66,"is disengaged :fromthe electric conductingsurface 34, when'the: energizing circuit-through'the motor field 49 and the mo-- tor-armature 48 :will be interrupted and the motor .willstop. v In this position of the drum, wall of, the contactors are de-ener-w ized, this :denergization having beenefected in .-step-by-step sequence inorder to gradually reduce the load on the generator or on the line. r -It. isahighly desirable that theitemperature .withinwthe casing .12 shall not fall belowapredetermined value which temperature may; be -o-the order of 500 F.,

that is, substantially the same-as -is5normallyi maintained within the casing when the web of material is being moved therethrough tobe dried. In order to-maintain the temperature atsubstantially this value, I pro- 72 in one side thereof and a corner recess 73 at the other side thereof substantially" as illustrated in Fig-3 of the drawing:

Contact brushes 74, 7 5 and 76 are'operative ly associated therewith, the brush 74 being connected to the supply circuit conductor 58, as shown in Fig. 2 of the drawing.

The brushes 75 and 76 are electrically con-.-

nected to two fixed contact members 7 7 and 78 that constitute a part of an electromagnetic relay that comprises a double arm con-' tact lever-79 pivotally mounted 'at its -cen-" The lever" tral electric-insulating portion. 7 9 is actuated by an electromagnet =com'-' prising a core member 81 pivotally connected thereto, and an energizing coil 82. A spring member 83 is connected to the other portion of the lever 79 and biases it to substantial ly the position illustrated in Fig.2 of'the drawing, where the conducting left-hand end portion engages contact members 77-and 84. 1 The contact member 84 is connected to the.

outer terminal of the field winding 49. A fourth contact terminal 85 co-acts with the conducting right-hand end portion of the lever 79 and is connected to the outer terminal of the field winding 51.

The energization of the winding 82 is controlled by a thermostatic member 86 located within the casing 12 and having a contact member 87 that is connected to one terminal of the coil 81. The fixed end of the member 86 is connected to one terminal of a suitablej push button-switch 88, the other terminal of which is connected to a contact member-89 that is adapted to be engaged by the movable portion'of the drag link 57 upon breakage of the-web of material. The switch 88 is of such construction that it will remain in either its closed or its open position when moved thereto.

The thermostat 86 will open to be disengaged from the. fixed contact member 87 as soon as thevtemperature to which it-is subjected exceeds a value of about 400 'F., that is, a value that is below the normal temperature existing within the casing 12 during operation thereof.

If it be assumed that the web of material has broken after several hours of normal operation, and if it be further assumed that the system, as controlled by the drag link57, has caused the motor to actuate the drum 32 -t0 the position in which the cooperating brushes are-in! the positions illustrated in F ig. 3,.thait=is, all oi the heating units have been de-encngizejd, and if tho switch 88 is in the; closed position, the thermostat 86 ,will

reinain initsopen position for a predetermined length of time until the normal operating temperature of 500 F. has been reduced, by reason ofheat radiation from the casing 12, to 400 below.

.Whenithe temperature drops to 400? For below, the thermostat 86 engagcs'the contact member 8?? to-completetin-energizing circuit extending. from supply circuit conductor 58- thnough conductou 91, drag lmk 7,.contact 89 ;iswitch; 88,-.thermostat .8(3,'.'contact member 8'Z=and actuating coil 82't0- the other supply cimuiticonductnmfiSL- .Ehe core 81 is. energized andxinowcs the lever-79' toEthe position indicatodizbyi-tlie bnokenlines inJEig. 2 0i 2c the drawing thereby closinganenergizing circuit..- from supply circuit conductor 58 thmugh-bmislm 74;: contact-.plate;7l=, brush 75, .con.txict:mbmher-. 7S,v lever (19,-. contact 85, field winding 51, anmature, 48- andconductor 68::t0- the: other supply circuit conductor 59. The motorsthen rotates the two drums clockwise,-.as viewed from the right,. whereby ti ie brus'hes-or' contact members-:40 and 4-1 will beicausedifto enga e: the electric-conducting. .surface, energize t 'e-"cooperatmg actuating coilsrohthe contactors and thereby effect energization'oi a portion only of tlltkllGfit-lllg units. -Thenotation of the'drums continuesuntil contact? member or-bnush 75-reaches the :recess; 72latz-whiohi time the energizing circuit through flue-motor is interrupted, and the motorwillistopn -.'Iihe-arcuate extent-of the electric conducting; Plate 71 is-so selected that, as nearly as,- possible, the amount of .clectric energy translated into heatin the heating-unitsthuszenergized will be just sufficient: to maintain approxin'mtely the normal'opemting'. temperature within the casing 12. This temperature may be made or main taincdat substantially 400 'F. as it is evident that if atemperature of 400 is exceeded, the thermostatic member 86 will be disengaged from. the contact member 87, the coil 82 will be deenergized and the switch lever 79 will be permittedto return to the is-closedthrough coil 55, moving the switch lever 53 -tothe position illustrated by the full lines in F i'g. 2, and causing energization of the field winding 51 of the motor 48 through-thecasing and: the dragzlink-vis cone to eifect. rotation of the drums to the. posis tions shown in Fig. 2 of the drawing. In

this position, all ofthe brushes associated A push 'buttoneontrolsw'itch9Q-hasbeen provided in order that the circuit normally;

controlled by. the drag link- 57, .mayhe closed,

to eifect euergization of all-.of the" heating.

units a short :time in advance-ot-the-time when the web. of paper is agam moving;

trolled thereby.

11 he system embodying my invention;

:provides a drag-link .controlledand -motog operated contact. drum {on effecting? .gfiSQBB by-step energization' and de-ener-gization; aplurality of heating units, ,With, limit switches associated therewith for: effect h1g5 de-energizationof. the .motor. at the desireds.

thermally controlled-in caseof breakageofi scribed drag link,. to effect: a-stephyg-step' energization andideenergization of aportioin only of the heating elements'-to-;mai n tain- .limit o travel-Lot the contacngdrum; auxiliary contact .drunris provided; that is:

.90,. theweb and through. the hereinbefore ;de=-

As hereinbefore. stated, ,1 'ihava illii s tratedii and described a system. embodying my iii vention .as applied toan electrically! heated paper drier un thereto. y i e p an.

Various modifications may 'benma'dei the systemembodying my invention withoutideeparting from .the spirit and seope'thereofi and all such modifications are intendedito'be covered by. theappended claims which are to be limited only by the prior art.

I claim as my invention:

1. In wheating systemfor drying a.- webof material, the combination with a plurality of heating units, of: means: forefieeting; the energization of said heating; units in; step-by-step sequence, a relay for controlling the energizationof said means, and a link, normally operatively ex-igaging saidweb: of-material and effective upon linealizingiv of said \\-'eb-to'actua.te--sai d relayto e'nergizesaid operating means toteflfeet deenergization of the heating units in-steprliy s tflpf sequence. a

2 In a heating: system for dryingfazinoving webof material, the combination with a plurality of heating unitsgoiadraig-link--' controlled means for effecting deenergp za tion of all of said heatingunits-in step by ste sequence in case ofxbreakage (at-said we and a thermal'eleinent, energized only in case of breakage of said web, for encv gizing said' means to effect re-energlzatlon of a predetermined number only of said heating units.

3. In a heating system for drying a web of material, the combination with a plurality of heating units, of means for effecting deenergization of said heating units in stepby-step sequence in case of breakage of said web, and thermal means for causing re-energization of a portion only of said heating units upon the occurrence of a predetermined temperature in said system.

4. In a heating system for drying a web of material, the combination with a plurality of heating units, of a reversible contact drum efiective to cause energization and deener ization of all of said heating units in stepy-st-ep sequence, a motor for actuating said drum, adrag link normally operatively engaging said web for controlling said motor, and a thermal element energized by said drag link in its inoperative position for causing said motor to energize and deenergize a part of said heating elements only in accordance with the temperature of said thermal elements.

In testimony whereof, I have hereunto subscribed my name this 8th day of July 1925.

STEPHEN A. STAEGE.

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