US1543830A - Continuous kiln and method of operating same - Google Patents

Description

Grinnell/Filed July 27@ 1920. 2 Sheets-Sheet 2 II IIIIIIIIIJI I.

j n n c DREssLER cognition# KILNAND us'mon or OPERATING smua -Paieazeailane'm 1925.l y

umrsn s-rArEsrA'rENr Orl-ical Y constan 'nnmumor sumas, omo, a'ssxcnon ro Anuamcnl Dnmsmn rusnx'als, nic., Or myosin-n. Y., A CORPORATION Or maw Yolix.

rcolr'rxmious mn am) nnrnon or orsna'rmo san continuada u'eppneeun semina. :aanstaan my a7, mao, renewed apra sa, laas. -rn'a 1 opnemen nea augen 2s, im. seran ne. 734s.

To all whom it l Beit known that ll, Comun DunssLnn, a subject-ofthe: King of Great Britain, and resident of-'Clevelamh in the county of l Cuyahoga andrSt-ate of Ohio, have invented rccrtainznewtand useful Improvements in t Qontinuous Kilns'and Methods of Operating Saine,'. of which the following is a specification.- i ,n l 'i la Y The generalobjectofthc present invention y is to provide kfor the e-ll'ective utilization of acontinuolus tunnel kiln in "heating/articles to a uniform temperature where,thc rate at which heatil should be imparledto thc articles ll varies from time to time.k v

My inventiamv'was primarily devised for, andis Ofl-"a siecial value ina plant. for casting andro ling aluminum. ln rolling alumiuumiit is desirable that the billets I should be `delivered to the rolls ata lteinperature of about 500 C. lf heatedabove this 'temperature the" 'billets approach ytoo closely to the melting point o aluminum,

aturealuxninum does not have the proper duetility. 'lhe billets are formed by castingyand' may be takenjout of the moulds while their interiors'are well abovel 500 U.,

. although'their surfacer .temperatures will.' 80 their be lesl than .500 C. In lsuch case',

whilefa billdnniy contain sulcient heat to bring it to an average temperature of 5 00O C., it'is necessary to place the billet -in an annealing furnace or soaking pit in which the billet temperature is made uniform Afrom surface to ntmgbepfore passing the billet to' the roll. f

If each ibilletfcast should be withdrawn from the mould in which it is formed and 40 placed'in the annealing kiln orsoaking pit, while stilllretainiug heat sullcient to ring the entire billet to the desired temperature -for rolling it 'would not necessary to use any fuel in heating'thefurmwe'or soaking '45 pit except ip'erhaps to make upy for some or all of the haat radiation or other losses from the furnace orl pit. Where the billets are annealed in a continuous tunnel kiln it `is noty practically "ble,'however, to put so .tu of melbilleeeinu, the ,kan kwhile mh billet maintains sacentheaiio" bring the billet to temperature for rolling. In tb Ollllition of a continuous tun-l nel kan the billets muet be fedrime uw entrance end of the kiln at the same rate as the are withdrawn from the exit vend of the ki n.y The billets must be passed irrimediately to the rolls. as they ar` withdrawn from the kiln .tolavoid cooling, and the rate 4atwhich the hilly'ctsa-re fed into the entrance. endl of thefkiln thus depends upon-the rate A specific object of the present-invention is to Vrovide a continuous tunnel kiln construction and mode .of Operation whereby billetsanay be properly annealed at theide'- ysircd temperature of; say 500 C., as fast or aafslowly as is necessary to provide billets riods in whiehthe for therolls when the operation of the lattcrlis irregular or intermittent, as well as when 1t 1s re ular and contlnuous, and

which will effectively utili-ze the available :elt ed inv-the billets fed into the h In thc practical carrying out of m invention lem ploy a continuous tunnel ki -n of the mutlled heated ty and preferably a kiln of` the wcll known lrcssler-ty )c having internal combustion. chambers .or heating the kiln, and provisions for maintaining a directed gravity circulation of the kiln atmosphere, and suppl heat to or, if necessary, abstract it from the kiln as required to bring the ,billets to the ihesired. temperature in .their passage therethrough regardless of the 'rate at whichthe billets are passing `through the'kiln or` of the amounts of heat retained by the different billets when introduced into the kiln. t In the preferred inode of accomplishing this, 1 pass a stream/of air i through the kiln chamber from its entra-nce end 'to its exil and. and then return this air to the entrance end of* nai combustion chambers wherein it is utilized so -far' as ma be required to support the combustion o fuel fed into the mufthe kiln through the maillesy or. inter' 3 'y Y i, .1,543,330

am in aie-kan my bowed -in otherways` than that shown, as by elec- 'tricity.-' ,L

Infthe preferredmode of o tion contemplated a` ionof the iln chamber aijacent its elivel'yend'ismaintained at,

or approximately atfthe desired annealing above, that .whenbillets containing considerable casting hieat .are being' inserted intothe kiln, the frstieiect of the 'air admitted to the' kiln through ythe duct K is to. cool the billets, btfas this`air and the billets travel towardi the exit end of the kiln they y receive heat from the combustion chambers and the pipejextensions H thereof and the apparatus should beso operatedy that a zone o approximately" constant tem krature which is that at kwhich the bil ets are to be delivered is maintained adjacent the exit end ofthe kiln. VWhen, as may sometimes happen, tbe hotbillcts contain more than the necessary beat yrequired tokbring therto a uniform delivery temperature no gas need be supplied to the combustion chambers and in thisvcaseexcess heat Aintroduced into the kiln :the billets and, notr lost by .-.liation froln'the kiln walls' is carried out of Uvkiln`r through ythe stackg'I. Under y other con @itions gasi's burnt in 'the Vcombusf tion .ch'mbers .att-the yrate required to make l up for radiation losses and for the small loss -oi heat cairied out of the kiln through the rate requiredyto make up `for radiation losses and fori thesmall loss of heat carried out of the kiln thron 'the stack and that required to bring t e billets up to the delivery temperature. .Y

In'cases 1n which it ls necessary or des1r-` able to anneal the metal in an atmosphere which is neutral or atleast ynot highly oxidizing, suchas an atmosphere of nitrogen, carbon mononide 'orl carbon dioxide, some mmlification of the apparatus shown in Figs. 1 and 2 must' be employed. One simple modification for use under such conditions is illustrated 3 and 4.- ,Infthis modification, the groupsof pipes Hl areal-ranged to take up less spaoe,.imeasured transversely ofthe kiln, than theeonstruction shown in- Figs. l and 2J a vAlongside of each` group of tubes ll is .a second group of'tubes HC conner-ted at their ends toheaders HB and HB2 respectively. Theheader HB' receives air,

i :is from the fan nthrougi; tbe pipes Q', and

the head1-v' lili* connects tooneend of a durf: lll)v in the;'coiresprmding kiln bench which runsv under the corresponding combustion chamber for its full length, being I connected to the latter atthe exit end of the kiln bv a port F1". AThe headers HA and HAz to which the pipes H are connected are arranged and connected as are the headers H and H2 of the construction first described.

A, pipe provided withl a controlling valve l e leads to the kiln chamber from a. gas tank P or other suitable source of supply of the neutral or non-oxidizing gas which istol form the atmosphere of the kiln :"cliambcr. As shown, the pipe P dischar es into the kiln `chamber through a nozzle A like the nozzle K first descrlbed.

the preferred construction shown herein and that my inventlon 1s capable of advantageous .use for other purposes than preparing alu- 1. The method of annealing articles pre-l viously heated to different temperatures which .consists in passing'the articles through an elongated annealing chamber and supplying heat to, or abstracting it from the chamber as'required to maintain the desired annealin temperature in a ipal portion of the kiln and tobringeach article to a tempcratureapproximately the same as said desired temperature during the passage of the article l V`through* the preceding portion of thechamstark I. Under other conditions ga's is ber burnt in thei combustion chambers at the `to dierent tem eratures which consists in from the rate at which the billets are cast, which consists in passing the billets through an elongated annealing chamber and su plying heat to, or abeti-acting it from the c amber as required to maintain cach/billet at an approximately constant annealing temperature during a final portion of its travel through the chamber, notwithstanding the variations in casting Iheat retaine'dby the billets when entered in. the chamber, andl It will b e apparent'to those skilled in` -the art that my invention may be carried out by means of other forms of kiln than- 2: The method of annealing articles heated A healing the billets at a rate varying at times 'variations in the speed at which the billets are moved through the chamber.

4. The method of supplying a variable demand for annealed billets vcast at a rate varying at times from` the rate at which the.

- 5. The method of operating a continuous tunnel kiln comprising an elongated kiln chamber and a combustion chamber therein extending Afrom the exit end of the kiln chamber towards its inlet end which consists in passing air through the kiln chamber from its inlet end to its exit end, and from the kiln chamber into -the combustion chamber at the exit end of the kiln chamber and supplying fuel to the combustion chamber at its exit end as' .required tomaintain a uniform temperature in a portion of the kiln chamber adjacent its exit end.

6. The method of vannealing billets'at a desired temperature and utilizing casting heat in so doing, which consists in passing the billets through a tunnelkiln chamber, heating said chamber by an, internal 1Coml bustion chamber located inthe kiln chamber and extending from the exit end toward theentrance end of the kiln chan ing air through the 4kiln cha entrance end towards its exit und am into and through the combu and supplying'luel to the conber adjacent the enit end el quired to maintain a portion chamber adjacent its enit end. :1 temperature.

7. A continuous tunnel in combination an elong combustion chamber extending -a the kiln from the delivery end o toward its entrance end, c fuel to said combustion chamba livery end of the kiln, an. air il combustion chamber from the kiln cham at t'he deliveryend of the lat-ter, and niet for passing air into the kilnj clit aber at entrance end.

8. A continuous tunnel kiln comprisiuc' in combination with an elongated chainh Y combustion chamber extending lengthwise el' the kiln from the delivery and of the l: ter toward its entrance end, means supplying fuel to said combustion chamber at the livery end of the kiln, and means for sugoH plying air -to said combustion chamber at the delivery end of the kiln including pr@ visions for causing the so supplied to travel longitudinally ci the kiln ch from the entrance end to the deliveryv ent. thereoil andtoabstract heat -from "the kiln chamber in its travel. A l

Signed at Cleveland, in the county olf Cuyahoga, and State oi Ohio, this 25th day of August, l). i924-,

Images