Патент USA US2411487код для вставки
NOV. 19, 1946. A, ¿_ WHITCOMB BLAST FURNACE CONSTRUCTION Filed April 5, 1945 ` 2,411,487 . 4 Sheets-Sheet l Nov. 19, 1946.. " A_ _|_ wHlTçOMB 2,411,487 BLAST FURNACE CONSTRUCTION Filed April 5, 1945 \1._' ~ 51N f 4 sheets-sheet 2 ¿lil , £25113» ,f W. Nov. 19,- 1946. . A_ J_ WHWCOMB ' BLAST FURNACE CONSTRUCTION 2,411,487 - Filed April 5, 1945 4 Sheets-Sheet 3 ' 18 16 f; if i 1 , VT- C5 H‘ \\\ l/ Y Y l ' t: \ I2 Y __1 x5? ` .‘ ' 1 mx; - [5 ? l _l1 ' ?/ff I f ï uá . 5 . INVENTOR. Af’z'h wmf Whi?comb BY ‘ Nov. 19, 1946. 2,411,487 A. J. WHITCOMB BLAST FURÑACE CONSTRUCTION Filed April 5, 1,945 1_1 Sheets-Sheet 4 n n vul Fig. 4 INVENTGR.- .Af-¿har J. Whi tcamb » BY ~ , Í l ` . „ Patented Ncv; 19, 194s Y «2,411,481 Arthur `J.' Whitcomb. Chicago, ÁFreyn E Company Chicago „ corporation crnnmc f i .' ’ m" ‘ Application Api-u s, 1945, scc-u1 Nc'. `ssa'nc` ` f 4 claims; ~„ (ci. zcßfzfn A, , ‘ ‘l The present"invention‘ïrelates.to improvements ingblastfurnace‘construction: ‘ ` ‘ construction having 1intcrlci¿innig„meaus.Á such,... as, above 'referred to which i'sfsimple Íändìnot likely ` »mast furnaces Iare*commonly 'provided' at `the togctoutotordea4 top thereofV with ‘two ‘ bellsï‘arranged ‘in series,` `an uppérmostïbell termeda small bell> an‘d‘ a lower material into the lfurmfvì.<_:eïwhile preventing the escape of "large ’quantities of‘gas from the'interior commercial service. of thelfurnace‘.- 'I'l'iefFci'm‘RiceY and `Whitcolnb 10 Patent No. 2,215,872, patented `September 24,1940, disclosesa blast; furnace Aconstructionv having lan large bell.':together'withy certain permissive inter i f i ‘ » Further objectswill appear'asfthe description proceeds. ` embodiment of the presentl invention; locking mechanism "therebetween: f 'ThisV ‘equip is mentï "is applicable under ordinarycon‘ditionsf-in which> the «pressure within the top ofthe blast ` ` ‘ c - ` Figure 2 is a. detail view§`partly in section, show ing a relief valve which may be usedin the prac- i tice of the present invention; 'f Figure 3_ is a detail view. partlyl in*` section, showing an equalizer valve which `may >be `used furnace Therevis appear not' ioohigh." `to be ‘certain " advantages u l f i i in op erating blast furnaces at~`increased internal pres 20 sures such that the pressure at the vtop of the blast inthe practice ofthe present invention ;: " u Figure 4 is a panel diagram showing relay' and other instrumentalities‘iwhich _may be `used in ' furnaces “might approximate one atmosphere carrying out the objects of the present invention; above mean atmospheric pressure.` The ‘use of ' and a‘nvequalizer'valve would `be necessary in connec valve being ‘utilized to equalize the pressure bef ` ' i u Figure Referring 1 ist0` a the diagrammatic drawings-view ' ` illustrating-one ` equalizer> `'valve ‘ between Vthe f small" >bell `‘and the essary‘to introduce a‘relief valve, the equalizer K" the large and small bells, an equalizer valve, and y a` relief valve well adapted to meet the-needs of opened alternatively“ 'to "permit" the insertion " `of be sufilcient. In‘ addition thereto it becomes `nec ' construction having interlocking means; between most bellßtermed'ïa ¿large"bell.` ‘ Saidïbells are tion with‘su'chfa'blast furnace, but Íit‘would not ‘ A further `object is to provide a blast furnace 25 ^ ‘ _ » Figure 5 is a diagram which may be> used in locating the instrumentalities in certain ‘of the relay circuits shown inllî'igure 4, the contactors l and coils in said relay circuits being located in line with the corresponding instrumentalities in -tweenïthe‘top of’the furnace chamber‘and the region between the bells prior'to opening theflarge 30 Referring ilrst to Figure 1, the letter A repre bell, therelief valve being used’toreduce the pres sents a small bell (located uppermostland the sure in the region between the -bells ‘to atmos letter B indicates a large bell (located lower Dheric‘pressu're -prior to opening the small bell. " most), which cooperate with vone another in the ` An‘object ‘of the presentinvention is to -provide charging‘of the blast furnace C, which provides a Figure 4. ' , ’ i ` a blast furnace construction having an equalizer 35 furnace chamber below "the large bell B. ~ The two bells A and B may beuarranged coaxially in a together with novel‘interlockin'g means therebe manner which is common in practice, the bell A tween and with the furnacebells. ' ‘ ì being controlled by a cable E, while the lamer l A further object _is to provide an improved blast bell B` is controlled by the cable D, levers F and valve and a relief valve such as above Vreferred to, furnace construction having interlocking means 40 G being> connected to ‘said cables D and‘E, re as above referred to in which themechanisms un-v `spectively, said levers F and G being connected tothe bells B and A, respectivelv. The cable E necessary movements before the next succeeding is connected to the hydraulic cylinder H, which movements may be made. f 4 ` l Y. is adapted to have a reciprocating movement A further object is to providea blast furnace 45 along a vertical'axis.A ` ‘ ' ' « construction`having interlockingY means of per Disposed within the small bell cylinder H is the missive typefin `that it gives permission >forcertain piston I, which piston is carried by the piston rod functions'to takefplace`,~~l:)ut` also requires them to J. Said piston rod J and piston I are stationarily take place as prerequisites to bell opening opera mounted. The piston rod J Vis provided with the 50 port K‘communicating with the space above the A further object is to 4provide a. blast ‘furnace piston I and is also provided with the port L com der control must‘actually respond and make their tionsi* i f i " construction‘having improvedinterlocking means which prevents the functioning of the parts under improper conditions. v ‘ ' ` ` " ` " municating with the space `below said piston I. . ’I'he letter- M indicates‘a'four-way valve,l which need not be described in detail, inasmuch as‘such A further‘j‘object is to‘pro‘vide a> blast furnace 55 valves are well known and are‘readily purchas > 2,411,487 . 4 i ate member I3 in a clockwise direction-to ymove _able in the open market. It will be suilicient to state that when said four-way valve M is in one the valve I3 from its seat to .open the equalizer valve Il. ‘ ' predetermined position, it provides communica As shown in Figure 1, the cable I3 is train . tion from the fluid inlet N through port L to the space below the piston I. At the same time said Ul over a sheave I3 and has its lower extremity connected to the piston -rod 23, which is con valve M provides access from the port K to an nected to the piston 2I in the cylinder 22. The _cylinder 22 is provided at its top. with the in exhaust O._ When said four-way valve M is in another predetermined position it permits access let conduit 23 and at its bottom with the exhaust space above the piston I. At the same time it per 10. conduit 24. >Said inlet conduit 23v is connected to the three-way- valve 23, which may be of ~ mits access from the space below the piston I to 'usual conformation.. Said three-way valve 23 is the exhaust O. Said four-way valve M is adapted from the ñuid inlet N through the port K to the „ to be operated by means of the motor P, which, ' » through any preferred power transmitting mech anism,- operates the crank Q. Said crank Q may 'be connected to said four-way valve M through any preferred mechanism. Said crank Q may also operate certain limit switches, which will be provided with' the air inlet conduit 23 and with the. exhaust conduit 21. Said valve 23 is re sponsive to the -plunger 23, which is adapted to ’ be ’controlled by instrumentalities to be explained more in detail presently. It may be stated briefly at this point that the valve 23 is biased to a posi tion wherein air above the piston 2|v will be"-ex- described presently.` 'I'he cable D is connected to the cylinder R, 20 which is also `adapted _to have a reciprocating movement along a vertical axis. Said cylinder ' R is provided with the piston S carried by the __ ’ hausted through the conduit 21 to the atmosphere and said plunger will be'raised to its uppermostv position. Air under pressure from the tsupply f conduit 23 may be. communicated through the piston rod T. Said piston S and piston rod T- conduit -23 to the region above the piston 2| to are stationarily mounted. Said‘piston rod T'is 2.5 force said _piston downwardly to exerta‘ down ward pull on the cablev I8 to liftthe counter provided with the port U,_providing access .to the weight I1> to move the valve member I3 'from its' space _above said piston S’k Said piston rod T ‘is seat to open the equalizer valve II. The piston also provided with the port V. providing access rod 20 of the cylinder 22 is provided with a cam to the space below said piston S. The letter W. 29 adapted to operate a pair of ,limit switchesf'to indicates a ’four-way valve similar in function to ythe four-way valve M above described. _be described presently. When - - Communicating with the space between the vsaid four-way valve is in one predetermined posi _ small bell A' and lthe large bell B is a relief con- -V ' tion, vit permits access from the source of iluid duit 3_0 provided with the relief valve 3l.' the pressure N to the space on the under side of the piston S, and at the same time provides access 35 details of which are illustrated in Figure 2. Said relief valve’controls access from the region be from the space above the piston S to the exhaust tween the bells A and B to the atmosphere. ' ' ' ‘0. When'said -four-way valve W is in another _ predetermined positiomîitpermits access from r \ Referring to Figure 2, it will be notedv that _ the relief valve 3| includes the _movable mem ber 32 adapted to be seated against the stationary _ valve- member 33. Said movable valve member the source of iiuid pressure N to the space above lthe pistoni S, and at» the same time permits ac cess from the space below the piston S to the exhaust O. Said four-way valve is adapted to be operated by means of the electric motor> Y, A 32 is pivotedto a swinging arm‘34 fast with an arcuate' member35. Saidarcuate member 33 has a pair of grooves in .its arcuate periphery, which, through any preferredpower transmit-. ting mechanism, is adapted to turn the crank _one for receiving a cable 33 which-suspends the counterweight 31. The other end of the cable 33 is secured, through means not illustrated, to the arcuate memberl 33. The other >groove in .Z. Said crank Z is connected to the four-wayl valve W through any preferred connecting means, _ which need not be described'. the arcuate periphery ofthe arcuate member 33 The numeral I0 indicatesa-by-pass conduit, one end of which is connected to the interior of. the furnace chamber adjacent to the top there- ‘ of and the Aother end of which is connected to . the space between the large bell B and thesmall bell A. Disposed intermediate of the length of the conduit Ill’is the equalizer valve I I, shown ' more in detail in Figure 3. By referringto Fig u_re 3 it will be noted that said equalizer valve II includes the stationary seat _l2 adapted to be contacted by the movable valve member~ I3. . Said movable valve member I3 is pivotally mount - ed at the end of a swinging arm I4, which arm is fast to the swinging arcuate member I5 jour naled within~ a portion of the -valve Il. Said arcuate member I5 has two grooves in its pe riphery, one for receiving the cable I3, from an extremity of .which is suspended the counter weight I1. The other end o! said cable I3.is fast receives the cable‘33, one end of which-is secured to the arcuate member 3l. By reference to Figure' 1 it will be noted that the cable 33 is trained over the sheaves 39 and 43 and has its ‘ other extremity connected to the piston rod 4I fast‘with the pistony 42 in the operating cylin der 3. f . ` Communicating with the space above the pis ton 42 in the operating cylinder 43 is the con duit .44 provided with the three-way valve 43. 60 Communicating with the valve 43 is the con duit 43 for supplying air under pressure. and` also communicating with the valve 43 is the con duit 41 for discharging air to _the atmosphere. The lower regi'on ofthe operating cylinder 43 is provided with the exhaust conduit 43 for pass ing air frombelow the piston 42 to the atmos phere. Said valve 43 is responsive to a plunger:v 43, which in its lowermost or-biased position with‘the arcuate member I3. The_counterweight connects the air supply conduit 43 to the region I1’serves to bias'íathe arcuate member l5 in a counterclockwise direction to hold the valve mem 70 above the piston 42, whereby to force said pis ber I3 against its seat I2. The other groove in the arcuate member.. I5 is provided with the » cable I3, one- end of which is fast with the arcu ton downwardly to exert a pull on the cable 33 to raise the counterweight 31 to open the relief valve 3l. Y _ . ' - The piston rod 4I of the operating cylinder 43 ate member I5. Lifting of the cable i3'will tend tn mise the; cnunterwelght l1 and move the 8.11311." 75 is provided with the cam 33, which> as the piston 2,411,487 5 rod moves relative to the operating cylinder“, controls a pair of limit switches, which will be described presently. , , Reference will now be made to a number of limit switches employed in the practice of the present invention. ' ` The motor P, as above indicated, operates the crank Q, which in turn, at two extremes of its travel, operates limit> switches 5I and 52. 'I‘he motor Y, as above indicated, operates the crank Z, which in turn, at two extremes of its travel, v operates the limit switches 53 and 54. The small bell operating cylinder H is adapted to control the limit switch SBC and the large bell ' operating cylinder R is adapted to control the limit switch LBC. The cam 29 movable with the piston rod 20 of the‘equalizer valve operat ing` cylinder 22 is adapted at the upper region of . 6 `. This pair of contacts LBC-i close as soon large bell B leaves its closed position. iisthe4 Limit switch 5| is biased to closed position and is open when the small bell valve M is in bell closing position.` Limit switch 52 is biased to closedì position and is open when the small bell valve M is Vin bell-opening position. _ Limit switch 53 is biased to closed position and is open when the large'bell valve W is in bell closing position. Limit switch 54 is biased to ' closed position and is open when the large bell valve- W is in bell-opening‘positlon. - Referring now to Figure 4, the various instru-` mentalities above mentioned are shown diagram „matically in an electrical control circuit. In addition to the instrumentalities previously men tioned, the diagram of Figure 4 shows the follow ing instrumentalities: its stroke to control the limit switch EVC and The small bell push button SBPB includes a at the lower region of its stroke to control the» 20Y walking beam operating member having the alter limit switch EVO. ' The cam 50 movable with the piston rod ’4| of the relief valve operating’cylinder 43 is adapted in the upper portion of its stroke to control the limit switch RVC and at the lower region of itsl ` stroke to control the limit switch RVO. natively operative buttons marked “Open” and “Close." When the "Close” button is depressed, a switch a is moved to open position and a switch b is moved to closed position. When the button “Open” is depressed. the switch a is moved to closed position and the switch b is moved to open The three-way valve. 25 for controlling the oper position. ` ating cylinder 22, which in turn controls the VThe large bell push button LBPB is also pro equalizer valve Il, is responsive to the solenoid vided with a walking beam operating member EV-solenoid, and the three-way valve 45 for con 30 provided with the alternatively operative but trolling the cylinder 43, which in turn controls tons "Open” and "Close'J’v Said large bell push the relief valve 3|, is responsive to the solenoid button controls the switch c, d and e. When the “Close” button is depressed, switches c and d Rif-solenoid. ` - ~ The various solenoids and switches abovemen are moved to open position and the switch e tioned are controlled from a panel CP supplied 35 is moved to closed position. vWhen the "Operi”4 by the electric conductors 55-55. The control button is depressed, switches c and d are moved panel CP is connected to the various switches and to closed position and switch e is moved to open solenoids through multiple wire cables, as illus~ trated in Figure 1. The circuits embodying said As shown in the diagram of Figure 4:,A the multiple wire cables, switches and solenoids will 40 motor P is provided with the armature Pa and be clear from the diagram appearing in Figure 4. with the two series iìeld windings Pb and Pc, The valve 25 associated with the equalizer valve which serve to operate the motor in two direc || is biased to a position corresponding to that in which the region above the piston 2| .is con Y The motor Y is provided with the armature nected to atmosphere, yWhen the ETV-solenoid is ~ Ya and with the two series iield windings Yb energized, the valve 25 is positioned to cause and Yc. . ' high pressure air to enter the region above the The control panel CP also includes relays EVI, piston 2|, thereby opening the equalizer valve ’ RV and EV, the operating coils of which are position. _ , ‘ tions. i ' ‘ A indicated in Figure 4 by the reference letters The valve 45 associated with the relief valve A50 .lust mentioned. The operating coil E'VI when 3| is biased to a position in which air under pres energized is adapted to close the pairs oi contacts ‘ sure is introduced above the piston 42, thereby EVI-i, EVI-----2 and EVI-3, which contacts are opening the rel-iet valve 3|. So long as RV-sole biased to open position when‘the coil EVI is not Il. ' « Y noid is energized. relief valve 3| is closed. ' energized. ’ Limit switch EVC is provided with two pairs 55 The operating coil ` RV when energized is of contacts EVC-_i and EVC-2. The pair oi? con adapted to close the pair of contacts RV-l, tacts EVC-i are closed when the equalizer valve which contacts are biased to open position when i i is closed, that is--when the piston 2l is up. the coil RV is not energized. The'pair of contacts EVC-lare open when the The operating coil EVwhen energized is adapt equalizer valve || is closed._ i l 60 ed to close the pair of contacts EV--|, biased Limit `switch EVC includes the pair of con to oâien position when the coil EV is not ener glze . tact" EVO-l, closed when the equalizer valve Il ` » _ The mode of operation oi' the above described Limit switch RVC includes two pairs of contacts embodiment of the present _invention is substan RVC-I and' BVC-2, both of which `are closed 65 tially as follows: when the relief valve 3|~is closed, that is-when After a load of material has been charged upon the piston 42 is up. . the small bell A, said> small bell may be opened Limit switch RVO includes a pair of contacts by pushing the “Open” button of the push but RVO--L closed when the relief valve 3| is open. ton SBPB. 'I'his closes the circuit through the is op en. 'I'he limit switch'SBC for the small bell cylin- " 70 series iield winding Pb and armature Pa because ' der includes the pair of contacts SBC-i, >closed of the fact that the limit switch contacts EVC-I Awhen the small bell A- is closed. . . The limit switch LBC for the large bell cylinder are closed (equalizer valve V|| being closed) and A limit switch contacts RVO-l are closed (the includes the. pair of contacts LBC-i, closed at relief valve 3i being open). 4'The motor P moves all times except when the large bell _B is closed. 75 the valve M intoposition to raise the small bell 2,411,487 , 7 - ‘ . ing coil EV. causing the contacts EV-I to open, `deenergizing the solenoid EV-solenoid, causing cylinder H and open the small bell A. As soon as the valve M is in this position, limit switch 52 opens and the motor 'P stops. Meanwhile ' limit switch 5I closes. When it is desired to close the 'exhausting of air from the upper portion’of the Acylinder 22, causing the equalizer valve || to close. the small bell, the “Close” button of SBPB is depressed. This closes the .circuit through the switch b and through the series field winding Pc and armature Pa. The motor P moves the valve M into position to lower the small bell cylinder This causes the limit switch contacts EVC-2 to open. When the. large bell B Vfully closes, limit switch contacts LBC-I- are opened. ' Coil RV is now deenergized because contacts ,EVI-l, EVC-_2 and LBC--l are all'Open. Con H and close 4the small bell A. As soon as the 10 sequently the contacts RV-I open, leading to , the deenergization oi the solenoid RV-solenoid, ` valve M is in this position the limit switch 5| opens and motor P stops. In this manner >the small bell A is opened and closed. This cycle may be repeated several times in order to'dis , thus causing the relief valve 3| to ì open. The cycle is thus completed. . The interlocking arrangement as illustrated and describedY is of the forced type; that is, the mechanisms under control must actually respond and make their necessary movements in order , charge `several loads of material upon the large bell. At intervals it will be desired to open the large to actuate the limit switches whose contacts are ` bell B in order to discharge into the blast fur included in the control circuits. The interlock nace the material which has been delivered from the small bell A. 'I‘he large bell B may be 20 ing arrangement is of the permissive type in that opened by pushing the button marked “Open" of the push button LBPB. 'I‘his closes the cir cuit through the switch c, causing coil EVI to be energized. 'I'he resulting closure of the con tactor EVI-_I causes the coil RV to be ener 25 gized. This causes contactor RV-I to close, it gives permission for certain’functionsy `to take> place, but it also requires them to take place as a prerequisite of bell-opening operations. 'I_'he interlocking arrangement illustrated and de scribed prevents the operations fromy taking place under improper conditions. . - l Recapitulating certain advantages of the pres ent‘ invention, the following may be mentioned: leads to the closure of the relief valve 3|. The 1. The small bell A can open only when" the instrumentalities in Figure 1 are shown as though the operationwere stopped with the re 30 equalizer valve || is closed andthe relief valve thus energizing the solenoid RV-solenoid. This 3| is open. lief valve closed, the equalizer valve closed and » ' the large bell and small bell both closed. v is a transient condition. ` This = Vrelief valve 3| is closed and the equalizer valve Energization" of the coil EVI also results in the || is open. closure of contactor EVI-2, completing a circuit 35 . through the coil EV as soon as the relief valve || closes (thereby closing the limit switch con - 4. The relief valve 3| can be opened only when the equalizer valve | I is closed and the . cause the rsmall bell A is in closed position. . Energiz‘ation of the- coil EV causes the closure 40 large bell B is closed» closure of the contacts EVI-3, completing a cir - 3. The relief valve 3| must be closed and the small bell A_must be closed before the equalizerl valve || can be opened. ' tacts RVC-D . Contacts SBC-l are closed be _of the contactor EV---|, which causes energize tion of the solenoid EV-soienoid.’ This leads to the opening of the of the equalizer valve ||~. En ergization of- the coil EV--l also results in the ~ 2. 'I'he large bell B can open only when the i Though a preferred embodiment of the pres ' ent invention has been described in detail, many modifications will occurl to thoseskilled in the art. It is intended to cover all such modifications 45 that fall within the scope'of the appended claims. What is claimed is:` 1. A blast furnace comprising, in combination, amature Ya of the motor Y, since the switch a furnace chamber, -a lowermost charging bell, d is closed and the relief-valve 3| is closed (whereby limit switch contacts yl'tVC--z are y a, topmost charging bell at the top of said cham- i closed) and the equalizer valve || is open (whereaf 50 ber, said bells> being arranged in series with one by limit switch contacts EVO--I are closed). another, means for operating the lowermost of said bells, means for operating the uppermost ofV The motor Y operates to move 4the valveyWA to ' a position to cause a large bell operating -"cylinsaid bells, a by-pass conduit adapted to connect der R to lift, opening the large bell B. As soon the space between said bells with said furnace as thc valve W has moved to the cylinder lifting 55 chamber, an equalizer vvalve in said conduit, mo position the limit switch 54 is opened, stopping tive means for said equalizer valve, a relief valve the motor Y. Meanwhile the limit switch 53 for providing communication between the space cuit through the series iield winding Yb and the between said bells and atmosphere, motive means for said relief valvefand means for interlocking “Close” button oi.' the push button LBPB. This 60 said operating meansv for the uppermost of said closes the circuit through the' switch e through bells with said equalizer valve and said relief the limit switch 53 and through the series field valve to permit said uppermost of said bells to winding Yc and the armature Ya. of the motor open only when said equalizer valve is closed Y. ’I'he motor Y operates in a direction to move and said relief valve is open. - ‘ closes. - ‘ The large bell B is closed by. depressing the the valve W into position for lowering the cyl 2. A blast furnace comprising, in combination, a furnace chamber, a lowermost charging bell, a topmost charging bell at the top of said cham ber, said bells being arranged in series withv inder R. As soon as the valve W attains this position the limit switch contacts 53 open. Low ering of the cylinder R results in the closure of the large bell B. ' ’ one another, means for operating the lowermost AThe depressing of the “Close” button of LBPB results in the opening of the switch c, which leads to the deenergization of the coil EVI, re sulting in the opening of contacts EVI-I, EVI-_2 and EVI-3. Opening of the contacts EVI-2 f .ruses the deenergization of the operat of said bells, means for operating the uppermost of said bells, a by-pass conduit adapted to con nect the space between said bells with said‘fur 75 nace chamber, an equalizer valve in said conduit. motive means for said equalizer valve, a relief valve for providing communication between the 2,411,487 10 space between sai'd bells and atmosphere, motive means for said relief valve, and means for inter locking said operating means for the lowermost of said bells with said relief valve and said equal izer valve to permit said lowermost of said bells to open only when said relief valve is closed and said equalizer valve is open. ' 3. A blast furnace comprising, in combination, valve to permit said equalizer valve to be opened only when said relief valve and said uppermost of said bellsl are closed. 4. A blast furnace comprising, in combination, a furnace chamber, a lowermost charging bell, a. topmost charging bell at the top of said cham ber, said bells being arranged in series with one another, means for operating the lowermost of , said bells, means for operating the uppermost of a furnace chamber, a lowermost charging bell, a topmost-l charging bell at the top of said cham 10 said bells, a by-pass conduit adapted to connect the space between said bells with said furnace ber, said bells being arranged in series with one chamber, an equalizer valve in said conduit, mo tive means for said equalizer valve, a relief valve for providing communication between the space said bells, a by-pass conduit adapted to connect the space between said bells with said furnace 15 between said bells and atmosphere, motive means for said relief valve, and means for interlocking chamber, an equalizer valve in .said conduit, mo said relief valve, said equalizer valve and said tive means for said equalizer valve, a relief valve operating means for the lowermost of said bells for providing communication between the space to permit the opening of said relief valve only between said bells and atmosphere, motive means for said relief valve, and means for interlock 20 when said equalizer valve is closed and said low ing said relief valve and said operating' means ermost -bell is closed. for said uppermost of said bells and said equalizer ARTHUR. J. WHITCOMB. another, means for operating the lowermost> of said bells, means for operating the uppermost of '