US2774368A - Blast furnace wind distribution control - Google Patents

Description

Dec. 18, 1956 s. H. JONES BLAST FURNACE WIND DISTRIBUTION CONTROL Filed Sept. 10, 1954 K .NQQR QW N l0 United States Patent The present invention relates to blast furnaces and particularly to control of the various flows of blast 'air to the different tuyeres.

It has become conventional practice to supply blast air at a constant volume rate that is calculated from various factors relating to the particular furnace and particular charge, and distribution of the blast air to the different tuyeres desirably is maintained in preselected ratios. Various causes tend to disturb these ratios and the primary object of the present invention is provision of a novel system that operates more eifectively than do systems previously proposed for accomplishing the same general purpose. Such systems, for example, are disclosed by U. S. Patents No. 1,726,298 and No. 2,083,046.

The conventional practice of supplying blast air at a volume rate that is maintained constant in spite of variation in the resistance to air blast delivery, the so-called burden of the furnace, involves variation in the power expended in delivering the blast air. Obviously the individual valves of the difierent leg pipes that deliver the air to the difierent tuyeres present a power consumption-- increasing source of resistance. To avoid introduction of unnecessary resistance, and resulting unnecessary power expenditure, it is desirable that all leg pipe valves be maintained as wide open as possible, while still maintaining the proper ratios between the volume rates of air delivery to the dilferent tuyeres. In the event that the total demand of the leg pipe valves, as measured bythe;

degrees to which all of them, are opened, exceeds the constant volume rate at which the blast air is supplied,

the required ratios among volume rates of delivery to the dilferenttuyeres will not be maintained. This is simplybecause there is not suflicient air for all tuyeres and their rates of delivery then are determined independentlyof;

their valve settings by flow rate-affecting factors that are individual to the various leg pipes and tuyeres, such as relative distances between the hot blast main and the cations of connection of the different leg pipes to the bustle pipe, and the local furnace charge conditions at the delivery regions of the different tuyeres. Furthermore, while changes in the furnace burden, which depends on the condition of the charge as a whole and which may change considerably during progress of fur: nace operation, or a selected change in volume, rate of total blast air delivery, tend to affect air flows to the different tuyeres in generally similar manner, they may upset the correct tuyere delivery ratios due to such individually differing factors as those mentioned above,

Another problem arising in blast furnace operation is that presented from time to timeby partial blockingof tuyeres by the furnace charge. As set forth in Patent No.

2,083,046, thiscondition, once initiated, tends to intensify itself by cooling of the charge in the region of the blocked tuyere, but may be overcome by forcing air through the blocked tuyere at the normal or an increased rate. This forcing may require closing adjustment of the valves of.

the leg pipes supplying the other tuyeres to provide the bustle pipe pressure necessary to the forcing and prevent disclosed by Patent No. 2,083,046, the system of the pres 2,774,368 C6 Patented Dec. 18, i956 cut invention accomplishes these results by imposing on each leg pipe valve relay a master signal that serves as a standard for adjustment of the valve of that leg pipe in accordance with the condition of the tuyere of that leg pipe, and which master signal is varied in magnitude in response to the positions of all of the leg pipe valves to provide for an increase in bustle pipe pressure if a tuyere is so blocked as to require it. However, in the present system the master and leg pipe signals are developed by and control operation of novel apparatus functioning in accordance with a novel theory and a novel'and markedly improved mode of operation. a

In brief, the novel theory upon which the present invention is based is development of a master signal that represents both the volume rate of blast supply and the furnace burden, thereby simulating the volume flow rate through a leg pipe and tuyere that are in normal conditions, and serving as a very accurate standard to which the actual air flows through the different leg pipes are compared for development of corrective signals that adgist the leg pipe valves to efiEect correction of a faulty An essential feature of the invention is that the master signal is developed from the blast supply by metering the volume rate of flow of a discharge from the hot blast main or bustle pipe. The discharge path is so arranged that it presents flow resistance that varies with the furnace burden. By controlling the rate of the master signal developing discharge in response to the positions of the various leg pipe valves, the system acts to maintain all leg pipe valves as open as is consistent with maintenance of the proper flow ratios, and it also responds to blocked tuyeres to open the valves controlling them, close other valves suficiently to maintain the required flow ratios and, if necessary, raise the bustle pipe pressure. An extremely important operation characteristic of the system is that in the event of a total demand of all leg pipe valves exceeding the constant volume rate of blast supply, an automatic closing adjustment of all leg pipe valves will occur,reducing the demand until it matches the pre-set volume rate of supply and the proper ratios are estabthe master signal is developed from a special pilotfiow discharged direct to atmosphere from the bustle pipe or blast main, preferably the latter since it is not subject to localized pressure variation as the bustle pipe may be. The pilot flow is discharged through a bleeder line presenting resistance to flow that simulates the furnace burden, and that automatically is varied to maintain that simulation as the burden varies, and preferably in response to leg pipe valve positions to obtain the desirable operating characteristics set forth above.

An important novel feature of the present system is that, in accordance with the theory of the system outlinedabove, and regardless of the particular type of discharge flow selected for master signal development, the master and individual leg pipe signals respectively are of magnitudes having proportional relations to volume rates of air-flow, and as hereinafter disclosed, conveniently may be developed by differential pressure type flowmeters.

Another important novel feature of the .system, and

.one that is not confined to a system wherein the master and leg pipe signals are developed by flow metering, is the arrangement and resulting mode of operation of the section of the system that regulates the master signal magnitude in response to the settings of the leg pipe valves. The cycling variation of the master signal and resulting cycling opening and closing of leg pipe valves disclosed by Patent No. 2,083,046, which are resorted to for accomplishing forced draft clearing of blocked tuyeres,

is avoided, and consequently in the instant system the.

leg pipe valves are maintained constantly in as wide open conditions as permitted by the three controlling ractors, total volume rate of blast delivery, furnace burden, and selected ratios of blast delivery to thedifferent tuyeres. f

:The' mastercsignal automatically is so controlled as to provide the following scheme or leg'pipe valve control.

A range of positions within which the leg pipe valves'are to operate under normal conditions is'selected, theupper limit of which preferably is at or near the, liniit of degrees below-the lower operatingrange limit, the master signal is so regulated as to constantly be variedin a sense to impose on'each' legpipe valve relay,a signal calling for continuing opening adjustment of the valve that it t'liiltl'OlS; Resulting opening adjustment of all o'f the'valves continues until at least, one'of them has reached the lower limit otthe operating range,;at which time the yariation ofthe'rnaster signal is stopped. In this conditioner-least one, and possibly more,jof the pipe valves :will have reachedthe lower limit of the operating range, After termination of'the valve opening variation of the mas tersignahanyfurther opening of, any valve is inresponse only to deficiency in the air flow 'thro'ugh the leg pipe controlled by thatvalveqflnthe event that any one valve reachesthe upper limit ofthe' operating range, the mastersignalcontrol automatically,

.starts to vary the master signal in a'sense to'initiate closing operation" of allleg pipezvalvesf However, in r 7 case of a severe air flow deficiencylthrough the legpipe controlled by the wide open valve, the opening legepipe signal applied to the relay controlling that valve will, 7 override the clesing master signal, and'the valveQof'the ,starved legfpipe.; will"remain open while all other valves; are increasinglyclosed. As distinguished from the abovck *menti oned cyclical variationtof the'pn'or art, this valyew clo sing' ya riation of the master signal'isin ot continued: j until the lower limit of the operating range has been' reached byflali valves, butlis terminatedas soon'as the j valves haveheen sufiiciently closed to eliminate'the de- F f fficiency through the leg'pipe controlled by the valve that started the closing operation, which issignalled by de snure erthat valve from the'limit position. Furthermore, all valves but the starved one may be closed to s t greater degrees than the lower limit condition so long as thatrstarved valveremains in the operating range.

Thus it will be seen that the operation characteristic ofthe systern ernbraces a lower non-operating valveposition range occupation 'of which by all' valves serves to vary the mastersignal in a sense resulting in adju'stment of all valves increasingly toward open andcontinumg until at -le'astrone'of themis in the operating range, and a second or-operating range oftvalve positionsjoccupation or by. any valve precludes variation of themaster signal in the sense :to'cause further valve opening, butwherein' any valve may befurthefi-OPened in response 'to deficiency in flow ratethrough the leg pipe' controlledlby it a nd an upper open limit of the operating rahg'e sreachirig of which byany other .valveserves tto, read ust thetmaster signal tothe-de reethat is necessary a! to remove'the valve from thei limit position and place it at-the'up'per limit or" the' operatingt range," in which condition it again becomes subject to readjustment by; variation of the flow rate through the legpipetthat it controls. a

t accompanying drawing is a schematic diagram of a portionjof a system arranged according to the inj ventionjand showing. schematically and in;detail agrelay and rfegulator syste rs ons-singers leg pipe valve,

the portion ofthe system for developing the master sig and valve for regulating the master signal magnitude, and two of the switching relay sections that'operate 5. the motor switching relays in response to the leg' pipe valve positions. An'jimportant feature of novelty of the system is that'the master signal is developed by discharg ing a bleeder pilot-flow. ofair, from the blast source through a; resistance that simulates the furnace burden. Describing the drawing'in detail, a h'otjhlast main is designated 5, i s'the supply source'and is assumed to be supplied withthotbl'astl airwat' a constant volume rate? withfwhi'ch plural leg pipes 7 iar e"connectedi for supply p-rovidingjplural discharge paths frorrimain'S and bustle pipe '6. tuyere are shown, it being understood that as many as required for the furnace are connectedto the' bustle pipe 6. One of the leg pipes 7 is provided with a flow I rate regulating valve assembly that is shown in section at 9, and the other with a similar valve assembly 10" shown in elevation, each suchvvalve conveniently. being.

a plug valve with a 'body iL that'is movable toward andaway from closed relation to seat 12, and that is" operated bya piston and cylinder assembly 13. a

The cylinder and piston assemblies 13 are'the p ower i 7 output units of first and second relay devices, generally turie provided with apair of receiverportsZO'that are narrowly V spaced in the direction of pi'ston'ltravel, :which' 1 40 also is the direction ofmovement of the jetpipfe orifice; as' the jet pipe swings about jaxis11 7. Thereceiverpo itsie '20 arecr'oss-connected by passages through the auxi liaryi 1 Mpistqn 18 with cylinder spacesat oppositefendsof 'thef "ends, .cau'sedi by. departure ofthejet tpip'egfro'm equalregistration with the two ports 26, the piston twillfbt displacement, that 'movement continuing until 'thefpoi't's' t clos'e 'thefconnected valve body ll." t

' The jet pipe has exerted upon 'it'a positioning a force that is proportionah to the'flow rate'bf air through. the leg pipe 7, thevalvebody 11 0f 'fvhich itfcontrols a through the piston and eylindef assembly :1 f end each of the leg' pipes js provided vwithiafconven;

' tional t'ype of volumeflow r' at e measuriiigde 7 -erably o f the differential pressureltype, udin restrictiyc 'meansjand" signal pipes'if or detectln as comprising a venturi typ-eflo'wje str'iction '22 havin nal, the motor switching relays that control the motor 7 V Main 5 delivers to 'a 'bustle'pipe-Q' which in convert-f: V tional fashion is assumed/to encircle a blast furn'acerand ing individual 'tuyeres such 'as that indicatedat*8, and

In the drawing only two'leg pipes and on'e pistom soithat'upon iinbalanceiof pressure tthr spisten moved by 'the' pres'sure" differential:in thedirectionof 1 '20 are. again in"-eq'u a1',registration -with'the jet pipe;

v By this structural arrangement the' pist'on 18 followsmovcment of the jetpipe'. Th'e' piston 18 is I connected to ja; control valve-21 0f spool type'that "s V 'movable in opposite directions from a neutral position respectively to connect the differentends of the cylinder V 55 of assembly '13 with a source of pressurized Ifiuid and with, exhaust in reversed senses respectively to a es pressures uiniregions' of differentpressures developed the 'fiowl restrictive meansgiSuch an assemhly isjshown anupstream pressure signalpipe23 tapped into it at" V locationspaced toward'thele'g pipe valveandbu's'tl-e pipe f jfromdtstpoint of maximuin'rest'riction, and antiwar-,1 I

flstrea'rn signal pressureipipe 24 tapped nfii it 1 I v narrowest part of its throat, these locations beiagreg ens' of dilfererit pressures developed -bytheflew iestricti6n r V greases foice balance device that opposes one to the other to develop a force signal of a magnitude proportional to their.

connected with the diiferent signal pipes 23, 24 and separated by a flexible diaphragm 27 to which .a signal link 28 is connected. The force exerted through link 28 by diaphragm 27 is exerted on jet pipe 16 and tends to position it. The senses of signal application, that is of the pressures of the difierent regions of the venturi 22 to the diaphragm 27, and of application of their resultant force, are such as to tend to swing jet pipe 16 in directions to open and close valve body 11 respectively in response to decrease and increase of rate of air flow through the leg pipe.

It will be seen that the relay mechanism so far described and which is provided at each leg pipe for operating the valve body 11 of that pipe, constitutes a flow rate regulator, operation of which tends to main tain the volume rate of flow through that leg pipe con stant by adjusting the valve body 11 to correct variation in that flow rate. Each of the relay assemblies is provided with a so-called ratio regulator by means of which setting of the relay for difierent volume rates may be accomplished. The ratio regulators of the diflferent leg pipe relays afford means for selectively varying the ratios of. volume rates of flow through the various leg pipes that are to be maintained by the system. Each such ratio regulator includes a lever 29 that is angularly positioned by movement of the motor output link 28 and a slider 30 that is movable, as by a handwheel 31, between and along lever 29 and jet pipe 16 to vary the point of application to the latter of the signal from diaphragm 27 transmitted by link 28 and lever 29, thereby to vary degree of response movements of the jet pipe,

to changes of force exerted by the diaphragm.

Ashas been suggested above, such factors as distance ofa particular leg pipe connection with the bustle pipe from the delivery location of main 5 may aifect delivery through that leg pipe, and this characteristic exists even though the legpipe in question be provided with a constant flow regulator of the type just described. For example, the volume rate of air that is drawn ofi by other leg pipes may so reduce the air supply to the one in question that it will not receive the proper proportional flow regardless of the setting of its valve by the relay.

T o obviate this difliculty, the relays such as 14 and 15 are provided with a common master or pilot signal additional to the signal developed by the venturi 22, which latter signal represents.the flow rate through the individual pipe. This pilot signal, which is applied in common to the relays of all leg pipe valves, represents volume rate of a discharge from main 5. In the specific form shown it is developed by a pilot line 33 that has an inlet in communication with the hot blast main and bustle pipe, as by connection at 34 to the former, and that has structure presenting to air flow through that line a resistance that is preselected and preferably adjustable. Conyeniently this pilot bleeder line 33 discharges to atmosphere which is assumed to exert substantially constant back pressure, and it is provided with flow restrictive means, which may be a control valve alone, but which preferably includes structure providing an orifice 35 for development of a difierential pressure signal. The upstream pressure, which is transmitted by a signal pressure pipe 36 connected to line 33 at the upstream side of pressures of the regions upstream and downstream of z orifice 35, the latter of which is atmospheric in the ar rangementshown, are exertedoppositely on'diaphragm 38. Therefore device 37 actually is a flow rate measuring device of the same pressure differential type as device 25. The resultant-force developed by diaphragm 38 is transmitted as a positioning signal to jet pipe 16 by a link 39. Senses of introduction of pressures to devices 25, 37, and of connection of the diaphragms 27, 38 to jet' pipe 16 are such, that the upstream and downstream pressures developed at the restrictions 22,- 35 are opposed, so that the leg pipe and bleeder line flow rate signals are summarized by opposition. Therebythe volume rate of flow through the leg pipe is proportioned to the bleeder line flow rate, and varies in response to its variation, and all leg pipe flow rates, by being varied in proportion to the bleeder flow, are maintained in the ratios selected by setting of their respective ratio regulators 29.

In further consideration of this characteristic, the senses of application of the various signal pressures and their elfects on the relay and the valves thereby operated may be considered. The upstream leg pipe pressure is applied to diaphragm 27 in a sense to swing the jet pipe 16' rightward or clockwise as seen in the drawing. This tends to operate the auxiliary piston and valve body 21 rightward, thereby to admit operating fluid to the upper end of the cylinder of assembly 13 and connect the lower end of that cylinder with exhaust, and thereby move valve body 11 downward toward closed position and tending to reduce flow rate through the leg pipe and the differential between the upstream and downstream pressures developed by venturi 22 and the former of which is opposed to the upstream pressure by diaphragm 27. The signal pressure delivered through pipe 36 tends to swing the jet pipe'16 leftward or counter-clockwise, as seen in Fig. 1. This tends to aid the downstream pressure delivered to diaphragm 27 by pipe 24, and atmospheric pressure exerted on diaphragm 38 aids and opposes the upstream and downstream pressures of venturi 22. i

The above arrangements assure the proper distribution of air flows among the leg pipes so long as the total of the leg pipe valve demands are within the volume flow rate of blast supply through main 5. I

Assurance of maintenance of the leg pipe valves in as nearly wide open condition as permitted by the blast supply, burden, and individual tuyere conditions, and assurance of a maintained flow rate to a partly blocked tuyere are provided as follows: Bleeder line 33 is provided with a valve 40 that is connected in series in line 33 with orifice 35, and upstream, toward main 5, from the orifice and the tap point of signal pipe 36. This valve 40 permits selection of a particular degree of resistance to air flow through the pilot bleeder line 33. It may be regarded as efiectively being a resistance to'flow that is parallel to the total furnace resistance, and its adjustment permits variation of the bleeder line resistance to to simulate the resistance of a specific furnace condition or a particular furnace burden and effect of such resistance or burden on air flow to a normally operating tuyere. Adjustment of this valve 40 towardsmore open or more closed positions serves respectively to increase and decrease the magnitude of the signal delivered to all of the relaysignal devices 37 through pipe 36, which in turn tends respectively to adjust all leg pipe valves toward' 'open or closed positions. Setting of valve 40 to stimulate a particular furnace burden, therefore, serves as a means of adjustment of all leg pipe valves to positions that are proper for that burden'and afiording a standard for regulation of each leg pipe flow.

The valve 40 is subjected to automatic adjustment operation to maintain it in correspondence with the furnace burden condition, to maintain the leg pipe valves as wide open as possible with maintenance of proper operation and to provide the proper relative adjustments of the leg pipe valves in case of blocking or impairment of air flow through any of them.

' ditio'n's. The revers -g'cir nifsef met een trmre1a s4a, s0. 7 v s p 7 J The variable pressure system 'ofeach leg pipe "control sidefofpowersupply 65.

metorrfi opp site directions, thereby farming to ad 'jirsft va1v'e140' respe n ely toward demand 'ctdsed' con- V p j 51ers provided with'a comnabnrenniiial 46that may'he'cofifiedt'dto one other terminals :47, or 48 of th respective circuits rion i'i'inn'ing' c'onditionfof the niotoi'l .sw tching or the motor terminals isfiaccoiiiplish'e'd "by rrrans of two valve position-responsive relays 49 so solenoids of thefse relays are so connected in an energiza'no'n'c'ircuit controlled v the leg pipe valves'that while all valv "are in relatively closed conditions lying ljlowflie lovve fliriiit of the is elec'lt'ed operating range,

' t'e'f inf'als' 46, 48' a're con ected, through, relay 49, to

gperaterrterqr 45in a dire'c'tiofi r ope valve 40. Open- .irig of valve (40' increases the ,difier'e'ntial pressure be;

fweenthe u stream region of'o'r'ifice sis and atmosphere,

iiie'reases the magnitude [of force developed .by relay' r'e'gillat'or' i'not'or 37 and operatesall r of the leg pipe .va'lve r'elay 's to :efiect openin'g' -adjustments of the valve 7 bodies 11 of *all leg pipe valves,

amrrmer, easy 49 is so ontrlolled thatfupon arrival of any valve body 11 at the degree of opening coffesporiding to the lower limit of 'the' operating range, motor t 'operatiofrlisjterniinated, arm's .ciit'zilitifor operating the v ifiotor' in the reverse djrec'tiofris cohditioned for closing i 5y relay" 50'; Upon arrival of anyone of the leg pipe 7 ,valvfdibodies 11 at l the preselected wide-open limit,

cor'tipli'shed' by a wide'variety' of remote. control sys temg arid is showntin a preferred form'as including a' var able pressure system for 'eaoh'leg pipe valve; which systems operate pressure responsive switch means that assembly is suppliedtwith operating'fiuid underpfessure pfipe. 54( It will be s ee'n; thatr each leg .i'alve V is'fconiiectedwitlra camSS 'thQat is. rotated int 'opposite 1 directions in respsns'eto f ops t and closing} movefiniits. "oruse waive lassemu' q elvejssgof s fluid pressur sglsremrnrmi h 'aalink 57 and s5 n5 58. Adi aphragm 59s is connected with s pring 7 581mm ftne expansi leiehamber er which it formsa wall is connectediwith aficon'tro'lled pressure lineafil r assess; a

I s fver rbiejetectrtcmotor 45 operativel'yf connected with ttre valve. This"r'iiot'of 'ha two eversing circuits,flthe iridrvidiral'el'qsirig of which re pective- 1 erve' fo'i-un the,

, cl that'c'irc'uit; fope'ri'ingof lio'tli circuits results in pressure, or leg fvalve 1 opening lirrirfit switching-- relay 62; includes-a contact 7 that is' conn'ec ted with] the first side'of supply '66 by the same; wiring that soqconnects contact 64; a contactor- 73 and a controlled contact 74' that'tis connected with;

power contact;72Whentpressure:inline- 6Greaches the selected limit; say fortyfive pounds. Cor'itactf741 is" connected by a line'175 witha' seconds common; control; line 'that' also is connected with the high pressure; switch ofeach of; thele g pipe valve assemblies; This linei is connected, to-a Contact 71 0f relay49. During de er'ter'giz'ed condition, or solenoid 69' contact 77 is 1 dis connected ,'but upon energization of that solenoid it is A eonnect'edby contactor 781with a controlled contactBZ,

The latter'is connected by a line 80' with one terminalf of the solenoid 839 of relay 50,the second terminal'ot" which is connected withthe second side of powerfsupp ly 66 by line 71'. It will be seen that energization'of the j I solenoid ofrelay 50 is: dependent upon energization''of r r r r solenoid 69 of relay 49." V V t w 7 3 Relayi49' includes: a second 'switch assembly "including a pair of contacts 82 which'are connected together by a contactor83 while solenoid 69 is de-energiz'ed and dis connected while it is energized. "Closing ofithis latter 7 switch serves to short-circuit. 'tnest'erminals 46,, 48105 motorAS, thereby operating motor in the directionto,

open valve 140. 7 Relay includes a 'similar' switch i I V 7 having contacts 84 and'a contactor 85' that connectstherrr V Wh'erithe solenoid 8 1 is'' energized to interconnect motor t'errtrinals tti, 4.7 to run the'motor; in the dire'ction to closetvalvetl. V r

The 7 operation of the pressure relays, andthe resulting'lcontrol of motor 45"and valve.

rose-squared to energizewtheicirc'iiit:that'operates the motorin valveclosing direction. Thisl mavhe ac- '40",'u'po1'1 blocking of any 'tuyere. is' as; follows." Reduc tion' of air flow through-the leg pipe tends. to equalize the magnitudes 'of tjhe' upstream and downstreamp'res5 '7 sures developed byfv'entu'ri 22, reducing the difierential across diaphragm 27"and permitting the force 'exerte d" and motor switching" V Ijy diaIihragmlS to override it. 5 The resulting operation" a V of relay ll lfis to start "opening v'alvel9;' Assuming that the system'has been 'operating; normally, the, low pressure 7 switchih'g relay of at leaston'e leg pipe valve. system' will;

" he closedfand in any-event thejone controlling the] blocked rmye're is eitherfalready closedior will be'come V Th'i'sicam'positions the 1 t to exert upon 59, a'force thatoppose'sfthatof Spriiig S' S iheg ey re maintain a proportional relation of the pres "sure in line 60 to-the angularposition of cam and the position ofl'valve 'bo dyili; The magnitude of pressure 7 in line 64') controls-low.and'fhigh pressure-responsive gvvitchingn'relays' 16ll,'62,' lwhic'h iarelconnect edt as shown tofcontr'ol energiztiori. of th'e solenoids of relays 49; 50

o du c e the scheme. of motor operation described e. may he assumed that the low pressure switch V responds a pressure of forty pounds per; square v inch; corresponding to a selected low limit" in theiope rab I g gran'ge ofleg 'pipe' valvepositions lto m ivqit sacon "setnbia 'is' connected by uses jog ith the sewer;

i'nisuhfrelation tothe' switch :Wil'll'lg of the, latter relays V of n g i il th' ant force on diaphragm closed as valve opening progresses; Therefore, solenoid 6 96f relay 49 will be energized, conditioning the circuit; t i

' ofsolenbid '81 of reIa'y 50 for energization and insuring thatthe hleedervalve" opening circuit 48, 82,83, 82,46

isop'enh Subsequent continuing opening of; the legipipe valve 'cor1t'rolling'the'blocked tuyere to'the limit position will rlesultiri closing of the high 'pressure'switch 62, ene ri-i' V gizing solenoid 81 and'closing'the hleeder; valve closing circuit 47',"84','-85, 84,46 startin'g motor 45 inthe direcf tion to close'valve 40. Closing valved!) decreasesvolume 7 rate of pilot now through orifice ,35, thereby decreasing the magnitude off'glifferfentialpressure across it, and the 1 re sultant foi'ce exerted on diaphragm 38 of each'of the they'rco' trol. tIhe'masterpressure signalsreductiomhowr.

lockedltuyere,sinceEthat-pressur andr'the result? 7 ded byfthe downstream ip essure exerted l P P 'is' *j la yfly l rge. The closing a'dustme'nt 1955 1 the unblocked lines'iwill continue so; long fas one lin'e s ,rela'vs oontrolli ng'fthe'unblockedtuyeres, and operating p i thefrlays to efieet closin'g 'adu'stment of the valvesthat- H 2'7, through pipeizt',which-inthe-blocked v V n jp ec ihe r ti f frl r ontrol-5 i sufli ciently-ghloeked to he m aintained fully open since, so i? I t 7 long aslonel'o'w' pressure switch 1 is closed the blee der ,valve openingicircuit43,182,?83, 82; 4:6"remai ns opefujjn i and so long as'one high'pr essure switch remain'sjclosedj i';

the lbleeder' valve- closing circuit 47 ,184, 85,84; 46: re 7 1 I l'inain s closed. As clearing of the blocked tuyere PI O l .gress'es air flow' 'througli it will increase, until he: ignal 7 force balance is such as ttolbeg'in closing adustn en :o'r. V, of

the leg '"pipe serve controlling i'tfl iAt commencement of this closing, the high pressureswitch 62 will open, terminating energization of solenoid 50 and closing adustment of valve 40. Thereafter, closing of the leg pipe valve of the'previously blocked tuyere will continue until it reaches the degree of closing corresponding to the selected limit, at which time pressure switch 61 will open, de-energizing solenoid 69, and starting motor 45 in the direction to open valve 49. Thereafter the system will operate by variation of the master signal and operation of leg pipe relays until it is in normal condition.

In the event that supply through main is insuflicient to supply all of the leg pipe flows called for by the conditions in which their valves are set, pressure at 34 will decrease, with a consequent decrease in volume rate of discharge through line 33 and orifice 35. This will decrease the magnitude of the master signal component tending to maintain the leg pipe valves open, and consequently the leg pipe valves all Will be adjusted to the more closed conditions called for by the actual blast supply and necessary to maintenance of the selected leg pipe flow ratios.

Opposite operation occurs in the event that blast supply exceeds the valve demand, which condition is reflected by an increase in master signal magnitude and results in opening adustment of the leg pipe valves.

Actually, with the possible exception of some abnormal situation, conditions will not occur wherein the blast supply is deficient or in excess of the valve demand, since the system responds in the ways described immediately above to any trend toward them rather than delaying response until they actually exist.

It will be noted that in line 87 that connects terminals 64 of the pressure-responsive switching relay 61 and terminal 72 of relay 62 is connected'a make and break switch 88. Opening of this switch in the relay circuit of any leg pipe valve control system disables that entire circuit from control of motor 45, thereby making operation of the motor by that leg pipe valve impossible regardless of its position and the resulting magnitude of pressure in its signal line 60, but at the same time not disablingcontrol by the circuits of the other leg pipe systems.

Such disabling is made necessary by provision of each of the individual leg pipe control assemblies with a manually actuated control by means of which the simple adustment of a control member between three positions can effect either automatic positioning regulation of the leg pipe valve by operation of the system as described above, or its adustment to a fully open or fully closed position. This is permitted by auxiliary relay mechanisms that operate in response to positioning of the manual control members.

A control assembly is shown by means of which selection can be made between this manual open-closed operation or automatic regulation. .Full disclosure of the mechanical and structural details of a suitable arrangement is made by U. S. Patent No. 2,635,584, dated April 21, 1953. In brief, the arrangement includes a control member such as hand wheel 90, rotation of which among three positions selects between automatic control of the leg pipe valve or its opening or its closing. In the system in question hand Wheel 90 constitutes the actuating element of a master relay control 91. The system includes two channels, which respectively include pairs of controlled lines 94, 94 and 95, 95. The master relay control is so arranged that it selects the one or the other of the two channels that is effective to control the sense of selective connection of the cylinder lines 96 with supply line 92 and exhaust line 93, thereby to select the ends of cylinder 13 that are connected with supply and erhaust.

' To accomplish this result the one of the channels that includes the lines 95 is the automatic control channel that is operated by the jet pipe 16, and valve 21 accomplishes the selective senses of connection of lines 95, 95, and the cylinder lines 96, 96 with supply and exhaust in response to the position of the jet pipe 16. .This channel includes I a cutoff valve 9 7 that is selectively positionable either ts block or unblock both lines' 95. i

The other channel includes a blocking and control valve 98 that is movable from a neutral position wherein it blocks both control lines 94, in opposite directions respectively to connect lines 94 with supply line 92 and exhaust line 93 in reversed senses. The movable body of valve 98 is connected to an actuator 99 that is controlled by the master relay control to position valve 98 in its neutral position while control wheel is in a position corresponding to automatic operation and to move the valve body in one direction or the other upon movement of the wheel 90 to a position corresponding to openingor closing operation of the leg pipe valve.

An actuator 100 is provided for the cutoff valve 97 of the other channel and this is controlled by master relay control 91 in such fashion that the cutolf valve blocks lines 95 while the hand wheel 90 is in the position calling for opening operation or that calling for closing operation of the leg pipe valve and valve 98 is appropriately positioned to accomplish that operation; While the wheel 90 is in the position corresponding to automatic operation,

master relay control 91 operates actuator to move valve 97 to unblock lines 95, and actuator 99 positions valve 98 to block both'lines 94.

Switch 88 is so actuated by hand wheel 90 that it is closed while the wheel occupies the position corresponding to automatic valve control and is open to disable the leg pipe valve position-responsive pressure switch relay control of bleeder valve 40 while hand wheel 90 is in positions calling for either opening or closing of the leg pipe valve.

- From the foregoing, the principles and modes of operation that characterize the invention will be apparent, and it is to be understood that many changes in the details of arrangement of the system and its elements herein disclosed may be resorted to within the scope of the invention as defined by the appended claims.

I claim:

1. 'Control means for a blast furnace Wind distribution system which system includes plural leg pipes for respectively supplying blastair to different tuyeres and each provided with a valve having a body that is adjustable in position to vary an internal pressure condition of that leg pipe, an individual relay for adjusting the position of each said valve body, individual means connected with each said leg pipe for developing a leg pipe signal of magnitude corresponding to volume rate of air flow through that leg pipe, means for developing a master signal and individual regulator means for each said relay comprising a'device for comparing magnitudes of the leg pipe signal of that leg pipe and said master signal and adjusting the leg pipe valve body of that leg pipe upon departure of said signal magnitudes from a preselected ratio to restore that ratio by adjusting that valve body to vary said pressure condition; said control means comprising a system for controlling the magnitude of said master signal, and operating, while all of said leg pipe valves are more closed than to a preselected limit degree, to vary said master signal in the sense tending to operate said individual relays to adjust said valves toward more open conditions, operating when any of said valves is opened to a preselected limit condition of opening to vary said master signal in the opposite sense, and operating to maintain said master signal magnitude constant while all said valves are more closed than said limit condition of openingand at least one of them is more open than said limit degree, said system comprising means for varying the magnitude of said master signal and including a control member that is movable in opposite first and second directions respectively to vary magnitude of said master signal in the senses respectively tending to open and close said valves by operation of said individual relays, plural signal devices respectively connected withthe different said valve bodies and operable .by movements of the latter to vary;

rial switch connected in the one of said motor circuits that is closable to operate the motor in the direction to adjust said leg pipe valve and vary said master signal in senses to open said leg pipe valves, and said motor switch being connected with said output member for being closed and opened respectively as it is moved to its first and second positions, and a relay switch connected with said output member and that is opened and closed respectively as said output member is moved to its first and second positions, a second relay having a solenoid and a second motor switch that is connected in the second said motor circuit and that is closed and opened respectively in response to energization and deenergization of said solenoid, a third relay having motive means provided with a movable output element and responsive to the positions of all of said leg pipe valves for maintaining said element in a first position while all of said leg pipe valves are more closed than a preselected limit condition more widely open than said preselected degree and to move said element to a second position when any leg pipe valve is opened to said limit condition, a second relay switch operable by said output element and opened and closed respectively in the first and second positions thereof,

and a circuit for energizing said solenoid and including said first and second switches in series connection,

7. The system of claim 6, wherein each of said leg pipe valve-adjusting relays includes a power unit having an output member connected with the leg pipe valve and oppositely movable to position it, and regulator means responsive to said leg pipe volume rate and master signal magnitudes and connected with said power unit for operating it to position its said output unit according to said magnitudes, and said system includes a manual control for each said leg pipe valve relay, including auxiliary relay means for disabling said regulator means from control of said power unit, auxiliary relay means for actuating said power unit to adjust the leg pipe connected with its output member in a selected direction, auxiliary relay means for disabling said relay circuit and comprising a third relay switch that is series connected therein, and a common manually operable control that is movable between two positions wherein respectively it renders all of said auxiliary means effective and inefiective.

8. A system for maintaining selected ratios of volume rates of flows of blast air to multiple tuyeres of a blast furnace through plural leg pipes individually supplying the difierent tuyeres from a common blast main and each of which leg pipes has a valve that is adjustable to vary rate of air flow through it, a reversible relay power unit connected with said valve for adjusting it, and a relay regulator having a control element movable in opposite directions and to various positions and arranged to operate said power unit to adjust said valve to a position corresponding to its own position; said system being provided with individual relay regulator means for each said leg pipe valve, comprising first and second difierential pressure expansible chamber force balancing devices each having a movable output element connected with said regulator control element and each arranged I and said system also including a bleeder line in communication with said main for discharging a pilot flow of air, means for measuring the volume rate of said pilot flow comprising structure providing a flow-restrictive orifice in said bleeder line, means for exerting on the output element of said second device of each said leg pipe relay regulator a force that is proportional to differential in pressures developed by said bleeder line fiowrestrictive orifice, and that is exerted on the regulator control elements of the respective relay regulators in senses to move them to effect opening and closing adjustment of all of the leg pipe valves respectively in response to increase and decrease in the volume rate of pilot flow, a bleeder valve in said bleeder line and adjustable to vary said pilot flow rate, and bleeder valvecontrolling relay means responsive to the positions of all said leg pipe valve-controlling relays, and arranged to respond to their positioning of all said leg pipe valves in conditions more closed than a preselected condition to continually adjust said bleeder valve in a direction to increase said pilot flow, to respond to opening of any leg pipe valve to said condition to terminate said bleeder valve opening adjustment, and to respond to adjustment of any leg pipe valve to a preselected degree more open than said preselected condition to adjust said bleeder valve toward closed condition only while the latter said leg pipe valve is open to said preselected degree.

9. Control means for a blast furnace wind distribution system, said system comprising a blast supply main and piping structure that provides plural paths of discharge of blast air delivered through said main and including plural leg pipes for respectively supplying blast air to difierent tuyeres each provided with a valve that is adjustable to vary volume rate of air flow therethrough, and individual relays respectively operable to adjust the difierent said valves; said control means comprising individual fiow metering devices each responsive to the volume rate of flow through a difierent one of said leg pipes to develop a leg pipe signal of magnitude that is proportional to that rate, an additional flow metering device responsive to volume rate of air flow through a selected one of said paths of discharge to develop a master signal having a magnitude proportional to volume rate of air flow through that path, individual regulators for controlling operation of the different said relays, including means, responsive to both the magnitude of said master signal and magnitude of the leg pipe signal developed from air flow through the leg pipe of which the valve is adjusted by the relay controlled by that regulator, to develop upon departure of the rate of the latter flow from a preselected proportional relation to said master signal magnitude an error signal of sense corresponding to sense of that departure, and each said relay being responsive to sense of error signal developed by its regulator to adjust the leg pipe valve in a sense to restore said proportional relation, and said control means also including means responsive to the positions of said leg pipe valves for varying the magnitude of said master signal, operating, only while all of said valves are closed to a degree greater than a preselected limit, continuously to vary said master signal in the sense to effect leg pipe valve-opening operation of said relays, and operating, only while one of said valves is opened to a'preselected limit condition more open than said limit degree to effect leg pipe valveclosing operation of said relays.

References Cited in the file of thislpatent UNITED STATES PATENTS 2,042,374 Wunsch et al. May 26, 1936 2,083,046 Burke June 8, 1937 2,379,008 Klinker June 26, 1945 2,420,415 Bristol May 13, 1947 2,635,584 Jacques Apr. 21, 1953

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