US2234173A - Broad coke oven - Google Patents

Description

March 11 .1941- c. H. HUGHES 2,234,173

BROAD come: OVEN Filed Jan. v24, 1940 5 Sheets-Sheet 1 TTORNEY March 11, 1941. c. H. HUGHES BROAD coxE OVEN Filed Jan. 24. 1940 3 Sheets-Sheetv 3 may BY Q i Patented Mar. 11, 1941 BROAD COKE OVEN Charles H. Hughes, Glen Ridge, N. J., assgnor to Hughes By-Product Coke Oven Corporation, New York, N. Y., a. corporation of New York Application January 24, 1940, Serial No. 315,317

' 12 Claims.

The present invention relates to by'product coke ovens and, more particularly, to by-product coke ovens of the broad, rectangular type.

It is well known by those skilled in the art that, in the earliest times coke was produced in moundshaped Meilers, similar to the old method of burning charcoal in heaps. -The beehlve oven was a modification of these, except that it was built of brick instead of sod or clay, and the earliest record of coking coalf'in a regular oven is an English patent to St. John granted in 1620 for making coke in a beehlve form of oven. Although a German chemist, Becher, received a patent in 1700 for recovering tar from coking coal, it appears that it was not until Claytons discovery in 1737 that the-formation of a combustible gas when coking coal was noticed. About the year .1767, a form of coke oven, producing coke and recovering some tar and ammonia, was

- constructed in Germany and was described as a dome-like re clay retort. appears to have been made to recover the byproducts, and a patent to the Earl of Dundonald was issued, and in 1792 Murdoch experimented with making gas from lcoal in retorts. These efforts bore fruit, an'd twentyI years later the streets of London were lighted by gas.

The earliest records of the rectangular, or retort. ovens show them in operation in Germany about 1830. They had open Walls, pierced by horizontal and vertical flues, and the walls formed a rectangular space which contained the charge. In 1856, Knab is reported to have built a group of retort coke ovens torecover by-prody ucts and illuminating gas. These ovens had flues on the bottom only, but, of course-no regenerator or recuperator system was provided. Moreover, there was no` attempt to furnish uniform heating to the oven sole, the,flre or flame passing from a grate through a central flue and then returning through flues on both sides thereof. The following year, Appolt built his first ovens in the shape of vertical and, later, horizontal re'- torts, using his gas only for heating his` oven through horizontal iiue's. This was about the earliest closed retort coke oven, utilizing the gas for its own heating. By 1861 the yCoppee coke oven of Belgian invention was in use on the Contlnent, and in 1873-74 it was introduced intov England. It had vertical -fiues and was of the non-recovery type.

About 1862, Carves of France introduced side iiues inaddition to the bottom flues of Knab.

- About 1880, Simon, an English-inventor, improved 4the Carves oven very materially by adding re- In 1781, an attempt 'no recuperators or regenerators.

cuperating flues. This ove'n had the oven flues placed horizontally, the gas and air being first burned'n sole ues located underneath the oven chamber, then passing up through a riser to the ovens and' down through three horizontal flues in 5 series. In the years 1881 to 1883, Seibel patented an Oven having horizontal flues and having neither grates nor regenerators. It is apparent that oven designs up to this time were so uneconomical of gas used in heating the ovens, or

the coals were so lean in gas, that grates for burning coal were built into the ovens and the gas was first admitted over these grates, the

amount of coal being such as to supply the re- 1r 0 quired additional heat.

The first ovens of the Otto type had been erected in Germany in 1881, and in the same year Huessner appropriated the Knab-Carvesmodel .and built a hundred ovens in Germany, thus A establishing the industry on a sound basis in that country, although the quality of coke from these ovens was inferior. In these' ovens the flues were horizontal. A very substantial improvement was made by Hoffman, who added the Siemens regenerator tothe Otto coke oven and thus provided the first really efficient coke oven, generally referred to in theart as the Otto-Hoffman coke oven. In 1888, Festner, a German inventor,

changed the Otto-Hoffman design by using horlzontal instead of vertical flues and abandoning the Siemens regenerators, replacing the same with a Ponsard gas furnace. Hoffman cooper- 'ated with Festner, and this design was called a Festner-Hoifman oven, having horizontal ilues and recuperatOrS. In 1887, the Semet-Solvay oven came into notice, the first of them having It appears that some of the principal features of Semets design were the introduction of the division wall, the 40 building of the oven flue system as a sleeve out of D-shaped tile. and the starting of the combustion at the top, or No. 1, flue, and, in general, providing a structure which was strong, easily heated and had a reservoir of heat in the division walls. Y

, From the foregoing historical survey of the development of the coke oven art,l it appears that all designs of ovens for coking coal sprang from four roots classified as follows:

1. The beehlve oven, which was developed from the mound of charcoal burners.

2. The Coppee `oven.`wlthvertical flues in the oven walls, these ovens being built narrow,`long and high.

" shrinking coals, as otherwise the wear on the The high, narrow coke ovens of the prior art Y described in the foregoing had various .important disadvantages. For instance, a recent standard type was usually of the order of about 45 feet in length, about 16 lfeet high, and about 17 incheslin width. and, because of their height and narrow-` ness, they had yto be constructed and built in very. large individual units, so that vthe original oost of` installation was extremely high. Generally speaking, it was not possible either to build or to l operate relatively small units of the conventional type at a lowcost.

Besidesthese economic disadvantages, the use of a high, narrow oven was limited to certain` coals or coal mixtures. Coals which expanded uponcoking could onlybeused if mixed with walls was too great, and the increasing pressure might have ledto destruction ofthe ovens. Using a-large vpercentageof shrinking coals, as neces,-

sarily became general practice, the coal shranky away from .the heating walls, causing the formation between cokeand wall of irregular gaps and crevicesfwhich acted as channels for the gases distilled from the coal. Due to the irregularity of these channels, heat could not be applied so as to produce a uniformlycarbonized coke in a short coking period,'-regardless of the method'of heatl" ing or control employed.

V- Itis `wellflrnown in the art that channeling brought the rich gasesinto immediate contact with the highly heated refractory walls, produc? 'ing two unfortunate results. First, the contact l" of the Vcrude gases withsome 1440 square feet of brickV at ther highest' temperature in the oven caused thel destruction of a part of the valuable lay-products contained' in the gases. Secondly, the gases acted as an insulator between the hot tion.v Again, the gases, beir'igmuch lower in temperature thanthe walls, took up considerable..

heat from them and thus prevented thisl amount of heatfrom reaching ythe core of the charge at tarding the coking vtime and were diametricaily opposed to the results desired, for it was, of course,

the purpose of the operation to .transfer heat from walls to coal charge as e'iilciently as possible and g in the shortest time. s Moreover, the heating ofg' the gases had the undesirable effect of passing the g gases to the by-'product plant ina s'uperheated state, necessitating rlarger condensing surfaces to oven was that thew'ldth of the chargey varied over .C001 them.

\ --A further disadvantage of the high, narrow coke i the length of the oven, for practical reasons being ilues .at the coke end ot the oven, necessitating smaller at the pusher end than at the coke discharge end. For the purpose of providing uni- ;form coking throughout this constantly'varying oven width, more gas had to be burnedin the adifl'erence in size of heatingriiues over the length trol heating conditions in vthese ovens, thev oven# l of the oven. 'I'his'requiredvery accurate control of the .fuel gas to .the individual nues..

"Under these conditions, it was diflicult to con- `smru'cturewas intricate and expensive, resulting 'in high-cost coke, and the coke produced was primarily suitable only for metallurgical purposes l.aas-m13 and not for domestic use.y The pressure in the metallurgical purposes.

Subsequently, a broad rectangular sole-tired coke oven attempting to eliminate these disadvantages was developed, but other diliiculties arose. Essentially, this broad oven construction provided a rectangular sole-tired coke oven having a multiplicity of long, independent, parallel heating flues arranged side by side, each of said nues being directly connected at each end to two shallow, horizontal hair-pin regenerators below and parallel to'and individual to each separate heating Iilue for alternatly supplying heated air to the nues and receiving the heat 'of waste gases discharged therefrom. Each heating ilue was pro vided with a burner or means for supplying rich fuel gas to both ends thereof.

Inthis manner,v all of the llames independent flues, entirely isolated from each other. 'I'hese names were all at one end of the oven and hence burned in the same direction,

/extendingtoward the *other end of the oven.

burned in i Burners were located at each end of the ues, and

eachheating flue and its associated regenerators could thus be alternately operated, independently of adjoining heating fiues and regenerators.

Although this broad type oven could be built in relatively small units, the entire heating system and the so-called regenerators were fundamentally incorrect. The oven was designedA for underring with rich coke oven gas only. The

use of :coke oven gas with preheated airl gave a short and hot iiaxe resulting in non-uniform heating of the long, straight, parallel andindeperature occurred at each burner.. producing danger points'or hot spots, Moreover, the regenerators were so designed that the waste gas and ,incoming air always circulated in a horizontal direction, which failed to give satisfactory and eilicient results. y 1 all. Both of theseeffects resulted'in greatly re` In other words, by eliminating some ofthe disadvantages of prior ovens, the broad oven de,- scribed introduced new diiliculties which were in the ends of the heating iiues in said broad oven were' overheated, causing'overcoking and quick overheating of the construction material of theA oven, while black spots, too cold for properv coking, developed in the centers of the flues'. learly, itgwas practically impossible to obtain proper coking of the center mass except, and then to only a small extent, by overooking the masses.

at the ends of the iiues. Then', the space provided above and below the regenerators was in.

adequate for the gases to spread or mushroom' out before going through the checkerbrlck. Moreover, the regenerators, which were individual for each nue, were insunicient in size and couldnot function satisfactorily. The velocity of the gases in the heating flues was too slow and in-the regeneratorstoo high for proper heat transfer. 0f course, not onlydid this non-uniform' distribution of heat greatly decrease the over-all eflipendent heating iiues. An excessively high temwalls and the coking coal, preventing cons ider able heat from reaching the charge by conducpart much mose serious than the former. Thus.-

rial andgreatly increased the cost of operation and maintenance. Although these diiliculties were well known in the art, and, from time to f time, various suggestions and proposals were made factory manner.

It is an object of the present invention to provide a by-product coke oven which eliminates the aforementioned difficulties in the construction and operation of conventional broad coke ovens.

It is another object of this invention to provide a broad,frectangular coke oven `in which v arious coals, tars and oils can be used to produce a coke substance with burning characteristics different from those of coke produced heretofore in high,

i narrow ovens or beehive coke ovens.

It is a further object of the invention to proiiue serving asa manifold for all of the ovens in said battery. 1

The invention also contemplates the. incorporation ina battery of broad'coke ovens of a pair of iiues common to all the ovens in the battery, serving as manifolds alternately for air to be preheated and for combustion products to'be discharged, and reciprocal to each other in function, whereby the direction ofow of the hot gases througb,the heating ilue system can be reversed, thereby insuring uniform heating over the entire floor of the oven. j l

It is also within the contemplation of the invention to incorporate in broad coke oyens, in novel combination with central air admission and waste gas discharge flues, in reciprocal operation,

a plurality of gas burners so arranged in the heating flues that the flames, which burn constantly and at both ends of the oven at the same time, will change direction with the reversal of gases through the heating ilues, lashing back and forth from one iiue to another.

vide a low-cost broad coke oven which is adapted to' produce coke having an open, free-burning cell structure, thereby providing a coke oven which is suitable for supplying small communities, as well as large, with a fuel supply of gas and coke for domestic-use.

It is also the intention of the present invention to contribute a broad coke oven of improved design in which means are incorporated for rapidly removing gases evolved during the coking operation, whereby prolonged contact of said gases with heated surfaces and consequent excessive cracking of hydrocarbons are avoided, thus producing an increased amount of light oils and tars.

My invention also provides a broad by-product coke oven having an auxiliary ejector system so disposed therein as to afford positive and controlled discharge through the gas offtake of gas andLsmoke evolved inthe coking chamber during charging of the coal, thereby avoiding a smoke nuisance whilev charging. coking coals into the coking chamber, whereby said coke oven vcan be' located in residentialtdistr'icts.

Another object of my invention is to provide a by-product coke oven which can burn either rich fuel gas or, alternatively, an atomized liquid fuel, such as fuel oil or tar, such change in operation being easily, `quickly and inexpensively accomplished', thereby allowing the operator to use up stocks of tar produced as a by-product, where these cannot otherwise b'e disposed of, to take full advantage of price differentials and other economic factors, and to/make available for domestic or'industrial service all of the rich coke oven gas evolved.

The present invention 'also has in-prospect the provision cia broad-coke oven having Aa series of interdependentV and. interconnected heating nues extending in continuous, serpentine character, under` the entire sole of the oven to aiford a continuous streamof the heatingl Vfluid throughout the whole heating system, and-having a plurality of burners inthe series to furnish a more or less continuous name throughout, whereby uni- The invention further purposes to incorporate in by-product coke ovens, in combination with a pair of flues common to all the ovens in a battery and adapted for central admission of airand central discharge of combustionproducts,

series-connected regenerators below and parallel to each.. oven and arranged to cause air which is being heated to ascend and to cause gas which is 'being cooled to descend, thereby obtainingguniformityof `flow and an effective change of temperature of the different streams.

Still another object-of my invention is to provide a battery of broad by-product coke ovens employing central air admission, wherein a novel combination of structural elements is disposed with respect to the series flue heating system of each oven in the battery for' the purpose of independently controlling the amount oi' 'air admitted to said heating system of-the individual oven.

This invention has the-additional purpose of providing a broad, rectangular coke oven having a system of series-connected heatingfilues, said system containing a plurality of burners and being adapted serially to conduct through the successive fiues all of the air required for combustion at the burners and all of the products of said, combustion, thereby considerably increasing the volume of gases constantly ,circulating through all heating ilues and -causing a proportionate increase in gas velocity, whereby stagnant, insulating gas films are effectively scrubbed from brick surfaces'and proper heat transfer is attained.

Moreover, the invention'has in view the contribution of a coke oven having a system of heating fiues so designed as to conduct the products of combustion to each successive flue in series, for the purpose of using' said combustion products to prevent high heats or hot spots in the vicinity of 'the fuel burners and to lengthen the flame by means of the increased velocity resulting from the increased volume of gases circulating through all heating iiues.

form heating conditions in all parts ofthe charge are obtained.

It is also an obiect of the invention to incorporate Lin a battery of broad coke ovens a' novel combination of .structural elements adapted `to admit air required for combustion to a common practical and industrial scale at `low cost and',

which is oi' h'igh structural strength, thus imparting long life to the oven and only requiring low maintenance charges.

Other and further objects and advantages of the invention will become apparent from the following' description taken in conjunction with the accompanying drawings, in which:

Fig.. 1 illustrates a horiwntal plansectional view of .a battery of four ovens embodying the principle of my invention, taken on line i-l of Figs.2and 3; f

Fig. 2 is a vertical transverse sectional view through two of the ovens, taken on line 2 2 of Fig. 1; v

Fig. 3 shows a front elevational view* of two ovens, taken on line 3-3 of Fig. 1;

Fig.' 4 depicts a vertical longitudinal sectional view of one of my ovens )taken on line 4 4 of Fig. 1:

Fig. 5 is a vertical sectional view of the special Fig. 8 shows this 'reversing damper in vertical sectional view. Y z I Broadly stated, according to the principles of the present invention, a broad, rectangular coke oven yis provided, having a heating system adapted tooperate with either rich fuel gas, suchv as coke oven gas, or liquid fuels, such as fuel oils and ltars.- As in my copending application, Serial No'. 301,172, flled October 25, 1939, the heating system consists of an'uneven number of sole ues, lpreferably ilve, interconnected inv series and arranged longitudinally of the oven to support and to vheat the floor of said oven. These heating ilues are connected by dampercontrolled openings, located at opposite ends of the series. with two sets ofyertical regenerators located below and parallel tothe heating ues 3 and ovens. The two sets of verticaliregenerators 'sis are alternately .used to supply preheated air to opposite ends of the series flue heating system and to receive the hot waste products of combustion. The regenerators, of whichIprefer to employ three, connected in series in each set,

have spacious, chamber-like es both above- .and below the checkerbrick,- giving the gases an opportunity to spread orv mushroom out before passing through-and :thus increasing the time of contact and aiording more effective heattransfer. Each set. of regenerators communicates with one ofv twoilueswhlch are -located transversely of the oven below the heating uesand preferably between the two sets of regenerators. My broad coke ovens are preferably arranged side `by side in a battery, and the two'transverse iiues passlngitudinany of said battery to serve an of the ovens in common as manifolds alternately for air to be preheated'and for-combustion prod-A ucts to be discharged. Means associated with said common transverse 'nues are incorporated in the structure for the purpose of reversing the flow through the heating systemin each oven,

usinga single reversing damper and a single pair of plate dampers for the entire battery. The

draft for each'oven is independentlyregulated by the dampers which control the openings connecting the heating ues with the regenerators..

The invention will now bmore fully'described to those sldlled in the art, reference being had lto -the accompanying` drawings illustrating a preferred embodiment'of the present invention.

Similar reference characters denote correspond- 5 ing parts throughout the various gures.

Referring,.now,more-speciiically to Figs. 1 to 4, it is readily observed 'that the oven battery of my invention comprises a pluralityof domed,

rectangular, broad coking -chambers H-I, hav- 1Q ing charging holes vor ports IIL-2 in their roofs,I adapted to be sealed: by covers H-'5.. An'olftake duct H-I is positioned near the top` of each charging holev andv communicates with a common gas duct C3, which is located along 15 the longitudinal axis of the oven roof. This `com-mon gas duct connects into an off-take pipe H-S nearthe coke discharge end of the oven. An' ejector J-I connected Vwith a steam or gas line is located in the oir-take pipe, and a 4va'lve 20 V|5 on said line ls adapted to admitsteaml or gas underv pressure to -the ejector. The coking chambers are adapted to le sealed against the admission of air by yoven doors Iii-f4 at I either end of each oven. There is a small doorl 2 5 l-I-l .in the pusher side oven, door.

Beneath each of these chambers and running parallel to the length of the oven, heating ues l, 2, 3; 4 and 5 are arranged in horizontal posi- 'tionand are seriesiconnected, being` separated 30 from each other Vby longitudinal partition Walls alternately spaced .from Opposite ends of the ovens to form 'a turn between adjacent ilues. y The interconnected -heating fiues are provided at said turns with burning means, such as gas- .35

burners 4B I, B2, B-3 and B-4, which-are supplied with fuel, as will be described infra.

Below the heating flues in each oven are located two series-connected sets of regenerators standard checkerbrick o r special checkerbricl-r in the usual manner. Regnerators R-I, R-Z .and

'Rf-3 v'are'conueeted .in -series with ue 5 and a transverse flue C-I -common to the entire .bat'

tery by passages P-I to P-II, inclusive (see 45 alsoFig. 6). Regenerators llt-4, R-S and R-S are similarly connected with ue and trans- `verse ue C-.Z by passages P-l2v to P-22, inelusive. Fiues C-I and C2 are preferably lolcated on `the same horizontal level as the re- 50 generators 'and separate the two sets. They are adapted to serve all the ovens in the battery as manifolds forair-to be preheated in the regenerators or for waste gas to be discharged 4tothe stack. The valternate'ilow of air and waste gas 55 andthe circulation through the heating fiues, re-

generators and said common transverse ilues are controlled by a reversing damper and plate .dempers at the respective ends of the transverse ilues and by dampers associated with the openings .00'

through which flues I and 5 communicate respectively with passages P-I2 and P-I, leading to "regenerators'R-4 and R-"I, respectively, as will be more fully explained hereinafter."

Passages P-2, P-6, P-'i and'P-IS, P-I'L'- 65 P`2I, which lie' above the -checkerbrick in re 'generators Rf-I, R-2, R-3 and R-I, -Rf-5,

R-G, respectively (see, especially, Fig. 2), are

spacious and chamber-like and, when these re-A generators are being used for waste com-bustion 70 products, 4they are adapted to give4 these waste gases an opportunity tospread or mushroom out before passing downwardly through said regenerators.

checkerbrick in said ,respective regenerators, are also spacious and chamber-like and are adapted to furnish an opportunity for air flowing to the regenerators to spread and mushroom out before its upward passage through said regenerators.

The terminal'ues, 5 and I, of the series flue heating system are connected through passages P-I and Pl2, respectively, with regenerators R--I and R--L The openings or ports V-l and V-2 from said flues, respectively, into said passages are respectively controlled by dampers D--I and D2, adapted to slide over said ports and to effect partial or complete closure, thus providing regulation of the draft in each individual oven.

The transverse fiues C-I and C-2, referred to supra as being common to all the ovens in the battery, communicably connect with the atmosphere at one end ,of said flues and with the stack at the other end. At the atmosphere end, dampers adapted to cooperate with each other are provided, and I prefer to employa pair of plate dampers D4 and D5, as shown in Fig. l. These dampers are connected together by a link of such length that the opening of damper D-4 to admit air to flue C-l effects the closing of damper D- to shut off flue C--2 from the atmosphere, 4and vice Versa. At the stack en'd of the ues, a valve or valves adapted alternately to open the two flues to the stack are provided. In my preferred embodiment, I provide an openwalled casing. containing a -slot S-I (see Figs.

'7 and 8) large enough to cover the outlets of both flues. In this slot a reversing damper D-3 is provided, said damper being slightly larger than a quadrant of a circle and being rotatable about anv axis located between the vtwo, flue outlets. In this manner, as will be evident from Fig. 8, damper D-3 is adapted alternately to close off ues C-I or C-2, so that when damper D-3 is in a position such that flue C-I is` closed, flue C-Z will be open to`the stack, and vice versa. Damper D`3 is equipped with a rack S-2 on its periphery, and a pinion S--S is located in slot S-l in such position that it can cooperate with said rack and thus actuate the damper.k The reversing damper D-3 andA the pair of plate dampers D-4 and D-5 are adapted to to operate together, so that, when flue C-lis open to the atmosphere, it will be closed off from the stack, and during the same reversal period flue C--2 will be open to the stack but closed oi from the atmosphere; similarly when flue C-Z is open to the atmosphere, nue C-I will be open to the stack. The reversing mechanism for operating these dampers is not shown, as thoseskilled in the art are familiar with the construction and operation. In a preferred embodiment, it may be brieiiy described as comprising the usual gear drives set in motion electrically by means of standard reversing valve mechanisms. A time clock, which is set for fixed reversal periods, is

adapted to make the necessary electrical contacts required for starting and stopping the motor used for shifting the gears.v

Fuel gas manifolds F-I and F--2 (see Fig. 4) run the length of' the oven` battery on opposite lsides thereof and are adapted to supply burners B-|, B-2, B-3 and B-l of each oven with rich fuel gas under a moderate and constant pressure. Riser pipes G-l and G-Z from the supply manifolds .to the burners are provided, and a special L and orifice are also furnishedfor the regulation of the fuel gas conducted therethrough. This L, depicted at Fig. 5, is equipped with a plug T-'I and a removable orifice member T-2 which isv adapted to be replaced by other similar members having larger or smaller orifices as re quired. Valves V-3, V-l, V-5 and V-G (see Figs. 3 and 6), locatedin the riser pipes from the supply manifolds to burners B|, B-Z, B-3,

and B-4, respectively, are adapted to shut off the gas supply entirely.

Pipe lines L--I andL-Z, adapted for carrying fuel oil or tar, also run the length of the oven battery on opposite sides thereof. They are connected with burners B-I, B-2, B-3 and B-l through valves V-1, V-8, V-S and V-I0, re-

' spectively, said valves being' adapted to atomize "respectively, and are adapted to furnishair for said atomization.

In the operation of the oven as an entire unit, oven doors H4 are closed and sealed air tight, as may be seen from Fig. 4.- Coal is charged through the charging holes H-2 in the top of piles are levelled olf in the usual manner by a levelling rod'K, introduced through a small door H-1 in the pusher side oven door. The charging hole covers H--5 are replaced and sealed airtight. Fuel gas,`fuel oil or tar is then burned with preheated air in the flues .underneath the coking chamber to provide a substantially uniform coking temperature for the entire area of the oven sole upon which the coal charge is supported. As is well known to those skilled in the art, the coking temperature varies, depending upon whether low or high carbonization is desired. Thus, a suitable temperature for low coking, such as about 600 to about 700 C., to a suitable temperature for high coking, for example, about 1150 to about 1450* C., can be successfully used. Reversal periods of suitable duration are employed, as those skilled in the art will understand, and a reversal of about minutes has been found to give satisfactory results `when underring with rich fuel gas, fuel oil or tar and using preheated air to effect the combustion.'

When the coal is coked, oven doors 'H-l are re- Arnovd, and the coke is pushed in the customary manner.

The gases evolved during coking rise up to charging holes H-Iand pass through off-take ducts H-'-3 into the common gas duct C-3, where all the gases evolved in the ovens merge into a single stream. In this manner, the gases evolved are rapidly removed from the coking chamber',

thus avoiding prolonged contact ofsaid gases with heated surfaces and consequent excessive cracking of hydrocarbons, an increased amount of light oils and tars being produced. The gases are deliveredv by gas duct C-3 to an off-take pipe H-- near the coke discharge end of the oven, and from there they pass to the by-product plant.v

Ejector .1 -l, employed to suck the evolved gases into the off-take pipe, is used only, during. charging operations. Steam or gas under pressure is admitted through valve V--I5. The flow of the steam or gas in an upward direction draws into the off-take pipe the gas and smoke evolved during the charging of the coal through the charging holes H-2. Without this induced draft, some of the evolved gases would escape into the atmosphere due to the` removal of the charging hole covers H5. The action ofthe 25 the oven (see also Fig. 2), and the cone-shaped 11o i and liquid fuels; The fuel gas is conducted at a tionl with Fig. 6, which illustrates diagrammatically the flow -of gases through the several ues,

ducts, regenerators, dampers and valves, for'the convenience o f those skilled in the coke oven art.

It has been pointed out supra that my improved `oven is adapted to burn both rich fuelgas moderate and constant pressure through supply manifolds F-I. and F--2 into risers G-I and G-2. Its supply to the burners is 'regulated through a special L, conveniently located, as de'4` scribed before, in each of the risers. vThe size of the orice used in the L controls the amount of fuel gas supplied to the burners. IWhen fuel oil or tar are used instead of rich fuel gas for underflring the ovens, gas valves V-3, V-I, V-5, and

V-B are closed. The oil or ytar from pipe lines I .-,I and L-2 ilows intovalves V-1, V-I, V-S and V-III, and air isalso supplied to these valves from air lines I r-B and L-L The airserves to atomize the liquid fuel, which then passes to the burners. The volume of air' yfor vaporlzing said liquid fuel is regulated by means of valves V-I I,

Assuming that regenerators R-I, 'Rf- 2 and R-l are being preheated by outgoingfproducts of combustion, damper Dbl is closed, .shutting oi flue Cef-I from the atmosphere,I and damper D-l is in such position as to close the outlet from flue C-2 to the stack, leaving`fiue`C-I open thereto. Damper D-5,. connected by a link to damper is open, so. that air to be preheated can enter linto flue 'CI-.2. It willfbe understood, of course; that, when an oven is'in operation, ports V-I and V-2 between the heating flues and the regenerators of that oven are open in some, degree. Although the stack draft for each individual oven is regulated byV the amount of closure of sliding dampers D--I and D-2 over ports` oven.

l The air to be preheated enters iiueMC-Z through opelr damper D-5 'and flowslnto'the mushrooxningchamber or passage P`22, which, as described above, is large enough to permit the air to spread out. 'I'he velocity of the air 'isthus reduced, and it then passes uniformly up through the hot checkerbrick in regenerator R-B to passage P-2 I', whence, by passages P-2l and P I9, the now partially heated 'air is brought to the spacious Passage P- I8`fbelow regeneratorvRf- Jf This Checkebrick is hotter than that lhe-lener- 4ator R-j, and the already heated air, upon pass-k in g through, is brought to a' st/ill higher tempera--A ture. Similarly, the air ows on 'through passages ,Pf-I1, P-I6, P-I5 and P-ll, successively, toregenerator R-l and from there emerges 'into passage B-I at a very high temperature.

Itwill be observedthat provision of relatively large gas spaces above and below the. regenerators permits the gas'f (here, air) -to spread out before entering thefcheck'erbrickgand thus lslows down its passage through theregenerators, giving l improved heat transfer. .Y The hotairpasses along' l passage P-Il above the vregerierator B -I and 1. `by passage'P-I2 and through port V 2 into heating nue l. This preheated eir'forthefeombustion of the fuel gas at'the burners is delivered in `flue I in great excess over the air requirements entirely' closed vduring pperationof the" 2,234,173 lejector in drawing these gases into the off-take for burner B-Iv and, after the combustion at burnerB-I, the air,'still in considerable excess of the requirements of the next burner in the series, passes mixed with the products of combustion to burner B-2, and similarlyto all burnregenerator R-2, and thence go down at reduced velocity through the checkerbrick inregenerate:` llt-2, to give up much of their remaining heat thereto and to emerge considerably cooler ln passage P1.below. Similarly, thevyvaste gases continue on through passages P-8, Pes and P-III and vdown through regenerator I12,?3, to emerge still cooler in passage P-I I. These cooled combustion products. flow through passage P-I I into flue C-I, whence they exit to the stack.

It is evident from the foregoing that, during the operation in the direction just detailedv (i. e., airfentering at damper D+S and waste gases going to the stack through flue C-I), the draft set up is in the direction from heating ue I,

through ues 2, 3 and 4,-to heating flue 5. Therefore, the i'lame at burner B-I, located at the turn between flues I and 2 (see also Fig.- 1), is deected by the draft into ilue 2. Similarly, the ilames of burners B-2, B3 and B-l are deiiected into fiues 3, 4 and 5, respectively. Thus, with the draft in this direction, there is no flame in'ue I, and the flames burn at the coke end (with'respectto the oven) of ues 2 and and at the pusher end of ilues 3 and 5. The hottest f end of flue Z-and this applies as well to flue is under the coke end of the oven, and the flue 'gets progressively less heat from burner B-I as one moves down toward the pusher end. Conand' least to the pusherend. while lues 3 and 5 1 furnish most heat to the pusher end ofthe oven, somewhat less to the centre, and least to the coke-end. Adding these two effects, the conclusion fs arrived at that the sum of the heat furnished at any point along the length of the oven is vabout the same as at any other'point, irrespecf tive of the distance from lthe actual burners themselves. v Upon a reversal of the draft, accomplished by closing. damper D 5, opening damper D-4 and rotating damper D-S from its position in front of the outlet of ue C-2 to a position closing off ilue-C-I, as indicated supra, ywith the preheated air'- entering at the coke end' (with respect to the oven above) of flue 5, the names of burners B'-l, B-3, B-2 and B-I are deflected into ilues 4 3, 2 and I, respectively. In this case, then. .the llames bur-"i at the pusher ends of ilues' 2 and 4 and at the coke ends of flues'I and 3, so that adaptability and flexibility never before attained the effect of each individual iiue upon .the oven is just opposite to that detailed in the foregoing paragraph. The cumulative or additive effect of the whole series of fiues beneath the oven, however, is exactly the same as in the other case. In

other words, the heat furnished throughout a full` cycle is practically uniform for the entire oven length, so that, with no black spots possible at the centres of the flues, there canl be neither overcoking at the ends of the oven nor undercoking at its centre. Moreover, the reversal of the names, being deflected alternately from one flue into another, eliminates the' danger of hot spots.

When the regenerators R|, R2and R-3 are raised to the temperature necessary for preheating the air, the directions of flow of the air and thewaste gases are reversed in the manner described in the preceding paragraph, viz., by opening damper D-l, closing damper D-5 and rotating damper AD-3 to close o flue C-l from the stack and to open iiue C-2 thereto. Air then enters iiue C-I through damper D-l and, damper D-3 closing off the outlet of said iiue C-l to the stack, the air fiows through passage 4P--II andupward through regenerators R-3,

R--Z and R-l in series, by means of the interconnecting passages P-l0 to P2, described supra. Passage P-l then carries the preheated air into heating flue 5. As detailed immediately above, the ames are then deected by the draftv into heating fiuesl, 3, 2 and I. The waste gases flow downward through regenerators R-l, R-'5 and R-B and through interconnecting passagesV P-l2 to P-22 and so enter flue C-2 and out to the stack.

Stack draft or the draft induced by a fan is used for drawing air into the regenerators and for removing the gases of combustion. As explained supra, the stack draft for each individual oven is regulated by the position of slide dampers D-l and D-2 over p'orts V-I and.V-2,lre

spectively. A y

From the foregoing description, it will be appreciated by those, skilled in the coke oven art that my broad, rectangular,l byproduc't coke oven possesses extreme. simplicity of operation. Furthermore, it will be observed'that it is a lowcost oven designed for adaptability to changing circumstances, and that these qualities make it lespecially suitable for supplying small, aswell as large, communities with a fuelsupply of gas and coke for domestic use. The foregoing, with the other advantageous features described herein, give my novel and improved' combination an by the coke oven art.

It will also be appreciated that, with my novel broad coke ovens, it is possible to produce al coke which is far more suitablefor domestic purposes than was the coke produced by the high, narrow ovens of the prior art. As explained supra, coke for domestic use should have an open, free-burning cell structure, and this type of coke can be made in my sole-fired broad oven. Level-ing off the coal charge in my oven over the entire horizontal heating surface gives a thin layer of. about 12 to about 20 inches in depth spread evenly over a surface .about 35 to about 45`feet long and about 8 to aboutl 12 feet wide. The free flow of hot, evolved gases through the thin coal charge and the low pressure to which the coal in the plastic state is 'subjected create entirely different carbonizing conditions from those prevailing in .the high, narrow ovens. An open cell structure results, and, invaddinon to the fact that a different molecular arrangement of the coke structure is developed, the carbonizin'g reaction is accompanied byless than the amount of' cracking of by-products which resulted from contactfwith 5 the hot, vertical surfaces of the prior art. Thus, the broad, flat oven herein described .can be operated to leave a suitable volume of volatile'matter in the coke to insure` the free-burning properties desirable in domestic coke. It will, of course, 10 be understood that an appropriate mixture of` coals can as readily produce a high grade'metallurgical coke in my broad ovens, so that my ovens have the great adavntage of being adaptable to the production of either domestic or metal- 15 lurgical coke.

Although the present invention has been disclosed inv connection with a preferred embodif ment thereof, variations and modifications may be resorted to by those skilledin the art, without 20 been indicated, those skilled in the coke oven art 25 will readily perceive that. otherI operative valvular means could be substituted for my arrangement and that other valve-actuating means could be used with satisfactory results. It will also be observed that, while I have preferred to employ a 30 yregenerative system under each oven which comprises two sets of vertical regenerators with each set comprising threeV regenerators connected in series, sets or one or two regenerators or of four or more 'series-connected regenerators could. be 35 satisfactorily used with relatively minor alterations and adjustments. Moreover, while I have described my invention particularly with reference to the coking of coal, itwill be readily understood that it is as easily adaptable to the cok- 40 ing of any carbonaceous material, such as peat, tar, lignite, pitch, culm waste and other low grade coals, fuel oil, bunker oils and other petroleum products, and the like. I consider all of these variations and modifications to be within 45 v -the true spirit and scope of the present invention, as disclosed in the foregoing description and defined bythe appended claims.

I` claim: I

1. A by-product coke oven of the tangular sole-fired type which comprises a broad horizontal coking chamber having a sole thereunder and adapted to be sealed against the admission of air, a plurality of'horizontal heating ,i'lues arranged in parallel-spaced position underneath the sole of the chamber and extending 1ongitudinally substantially from end to'end of the oven, longitudinal partition walls alternately spaced from the ends of the oven separating said ues from each other and connecting said nues 00 in series to define a single serpentine heating passage under substantially the entire sole area of s aid coking chamber, burning'me'ans located at each turn between adjacent heating nues and" positioned in substantial alignment with the partition walls whereby flames issuing from said burning means can be deflected by a draft along either of said adjacent heating flues depending` upon the direction of the draft therein, means for supplying uid fuel to said burning means, air in- 70.

let means- .for supplying air to said burning means, a waste gas stack for removing products of combustion of said burning means from said heating flues. a set ofv regenerators at each end of the oven respectively connected to the endsv 1I broad rec- 50 while at the same time disconnecting the other 8p of said heating passage, a pair of chimney-air f 'ber and in communication with said sets of reilues positioned transversely to the coking chamgenerators, single chimney valve means for connecting one of said` chimney-air ilues to the chimney while at the same time disconnecting the other-chimney-air flue from thel chimney, and

single aix` valve means cooperatingwith said chimney valve means for connecting the chimneyair flue disconnected from the chimney to the air chimney-air ilue from the air,l whereby a ilow of 'l gases is effected throughsaidregenerators and said heating passage in alternating directions and whereby substantially uniform heating conditions are provided over substantially the entire"A sole area of the coking chamber. f

2. A by-product coke oven of\the broadfrectangular sole-fired type which comprises a broad horizontal coking chamber having 'a sole-thereunder and adapted to be sealed against the admission of air, a plurality of horizontal heating nues having an odd number and arranged in par-` allel-spaced positions underneath the sole of the chamber -and extending longitudinally substantially from end to end of the oven, longitudinal partition walls alternately spaced from the ends Aof the oven separating said ilues from each other 1 andconnecting said ilues in seriesvto dene av .130

single serpentine heating passage under substantially the entire sole areaof said coking chamber, a burner located at ,each turn between adjacent heating iiues and positioned in substantial alignment with the partition walls where-l by flames issuing from said burners can be de@ ilected by a draft along either of the nues-adjacent'said' burner depending upon the direction of the draft therein, means for supplying iluid' fuel to,said burners, air inlet means forlsupplying air to said burners,'a waste gas stackfor removing products of combustion of said burners from said heating ilues, aset of vertical regenerl ators at each end ofthe oven having a chamberlike space in the upper and lower portions thereof to cause `spreading out of the gases passed therethrough.- ducts connecting .an upper chamber-like space in each set of regenerators to the terminal heatingilues of said heating passage, a pair of horizontal` chimney-air fiues arranged transversely to said coking chamber and in communication with said sets of regenerators, ducts connecting a lower chamber-like space in each set of regenerators to. said transverse chimneyair ilues, single chimney valve means for'con-l necting one of said chimney-air nues to the chimney while at the same time disconnecting the other chimney-airtime. from the chimney, and single air 'valve means cooperating. with said chimney valve -means for connecting the chimney'- air flue Adisconnected from the chimney to the airwhile Aat the same time disconnecting rthe other chimney-air-ilue from the air; whereby a flow oi' gases is eifected through said regenerators and said heating passage in alternating directions and whereby substantially uniform heating conditions are provided over substantially the A entire sole area of the coking chamber. Y

3; A by-product'coke oven` of the broad lreci tang'ular sole-fired type' which comprises a broad horizontal coking chamber having a sole thereunder and adapted to. be sealedl against the admission lof air, a plurality of horizontal heating nues having an odd numberand arrangedcin parallel-spacci position' underneath the sole of the chamber and. extending longitudinally substantially from end to end of lthe oven, longitudinal partition walls alternately spaced from the ends of the oven separating said ilues from each other and connecting said ilues in series to denne a single serpentine heating passage neath said heating iiues having a chamber-like.

l space in the upper and'lower portions thereof to cause spreadingl out of the gases vpassed therethrough, a duct at each end of the oven respectively connecting an upper chamber-like space in each set of regenerators to the terminal heating ilues of said heating passage, a pair of horizontal chimney-air ilesarranged transversely of saidcoking chamber and in communication with said sets of regenerators, ducts 'respectively connecting a lower chamber-like space in each set of .regenerators to said chimney-air transverse ilues, air-inlet ports at one end en' said transverse chimney-air fiues, a, waste gas stack at the other end of said transverse chimney-air ues, single chimney'valve means for connecting one of said chimney-air ilues tothe chimney while aty the same time disconnecting the other chimney-air flue from the chimney, and single air valve means'cooperating with said chimney valve means for connecting/the chimney-air flue disconnected from the chimney to the air while at the same time disconnecting the other chimney-air nue from the air, whereby a ow of gases is effected through said regenerators and said heating passage in alternating directions and whereby substantially uniform heating conditions arev provided over substantially, the entire vsole v area of the coking chamber.

, 4. The yby-product coke o'venconstruction-as set forth in claim 3,' wherein the valve means for interchangeably connecting one o`f the transverse ilues with the, air inlet ports and the other with the stack comprises a pair of plate dampers cooperating with said air inlet ports, and a quadrant-shaped reversing damper cooperating with said waste gas stack, said dempers being constructed and arranged to be operated in predetermined alternate sequence.' f a 5'. A by-product coke oven o't the'broadrectangular sole-'fired type which comprises a broad' horizontal coking chamber having a'sole ther under and adapted to be sealed against the admission ci'v air, a plurality of horizontal heating ilues having an odd number and arranged in parallel-f spaced positions underneath the sole ofthe chantment with the partition walls'wherebyames issuing from'said burners can be deect'edvby a draft along either of the nues adjacent said burn- 7g -ses therein, means for supplying rich f uel gas to .said

burners, means for supplying liquid fuel and atomizing air under pressurey to said burners, valve means for selectively controlling the'admission of said gaseous andv atomizedliquid fuel, a pair of sets ofserially connected vertical regenerators located beneath said heating flues having archamber-like spacein the upper and lower portions thereof to cause vspreading out ofthe gases passed therethrough, a. ductat each Aend of the oven respectively connecting the upper chamber-like space of a terminal regeneratorof each of said sets of regenerators tothe terminal heating nues of said heating passage, damper means intermediate to said ducts and said terminal heating fines, a pair of horizontal chimney-air ues arranged transversely to `said cok'ing-chamber and in communication with said sets of regenerators, go ducts'respectively connecting the lower chamberlike space of the other terminal regenerator of each ofvsaid sets of-regenerators to said transverse chimney-ai;` flues,'air inlet ports at one end of said transverse chimney-air flues; a waste ges stack at the other end of said transverse chimneyair ilues, `single chimney valve means for connecting one of said chimney-air nues to the chimney while at the same time disconnecting the other chimney-air iiue from the chimney, :and single air valve means cooperating with said chimney valve means for connecting the chimney'- air flue disconnected from the chimney to theair while at the same time disconnecting the other chimney-air ueifrom theair, whereby Va flow of gases-is effected through said regenerators and said heating passage in alternating directions and whereby substantially uniform heating conditions are provided over substantially the entire sole area of the coking chamber. v v

6. The byproduct coke ,oven construction as set forth in claim 5 wherein each of thetwo sets of regenerators comprisesl three vertical regenerators serially connected with each other in'such manner that the lower chamber-like space of the 1'5 terminal regenerator connectedto the heating nues is connected to the upper Xchamber-like space of the middle regenerator. and that the lower chamber-like space of the middle regenerator. is connected to' the upper chamber-like space of the terminall regenerator connected to a transverse flue. i i

'1. A coke oven battery comprising a plurality of broad by-product coke ovens arranged side by side each of which comprises a broad horizontal coking chamber having `a sole thereunder and adapted to be sealedfagain'st the admission of air;

a plurality of horizontal heating flues arranged rin parallel-spaced position -underneath the sole of the chamber and extending longitudinally subw stantiallyfrom end to end of the oven', longitudinal partitionv walls alternately spaced from the vends of the oven separating said nues from each other and connecting said nues in series to define va single serpentine heating passage under ,sub-v '55 stantially the entire sole area of said coking chami -ber, a burner located at each turn between adjacent heating flues and' positioned in substantial alignment with the partition walls whereby llames issuing from said burners can he deflected 70 by a draft along either of the ilues adjacent said burner depending upon the direction of the draft therein,Y means .-for supplying ,iiuid fuel to said burners, a set 'of regenerators at each end of said heating e, a pair of chimney-air nues arranged transversely to said plurality df coke ovens 9 and in common'for all of the ovens of said battery communicating withl said regeneratorn Vair inlet ports at one end of saidttransverse chimney-air flues, awaste gas stack at'the otherend of s'ald transverse chimney-air nues, single chimney valve means for connecting one of said chim'neyfai'r ilues to the chimney while at the same vtime disconnecting vthe other chimney-air flue from' the chimney, and single lair valve means cooperating with said chimney valve means for connecting the chimney-air flue disconnected from -the chimney to the air while at the-same time disconnecting the other chimneyfair flue from the air, whereby a ilow of gases is effectedthrough said l regenerators and said heating passage inaIternating directions and whereby vs\.ib.-ita .ntially uniform l heating conditions are provided. oversubstantiali ly the entire sole area of thecohing chamber,` j g 8. A coke oven battery comprisingla plurality of broad by-product coke ovens arranged side by side eachof which comprises abroad horizoutalr,

coking chamber having asole thereunder and adapted to be sealed againstthe admission ofair,

a plurality of horizontaljheating yiiues arranged yiin parallel-spaced position underneath the; sole 'of the chamber and extending longitudinally sub.

stantially from end toend of the oven, longitudi-` nal partition wallsalternately lspaced fromtheV ends of the oven separating saidiilues from each other and connecting saldilues' in seriesto define Y a single serpentine `heatingpassage under 'sub-u:

stantially thejentire-so`le area of said'coking l chamber, a burner located at each turn between 4adjacent heatingfluesfand positioned in substanf tial alignment with the partition vwalls wherebyl 'flames issuing from said burners can be deilectedf vby a draft along eitherwof the flu'es adjacentsaid burner depending upon the direction of the draft .thereingmeans for supplying, rich fuel gas to said v burners, ineens' ,for supplying :liquid fuel and atomi'zing air under pressure to said-burners, valve means for selectively controlling the admission -of said gaseous 'and atomized liquid fuel,- two' series of vertical regenerators located beneath the he'ating nues and having inner' portions of 'checkerbrick and chamber-like spacesboth above and."

4below the checkerbrick in each regenerator' thereby giving gases passing through saidregenerators .an opportunity to mushroom'out before passing through said yoheckerbriclr and thus increasing nectin'g the upper chamberlike space of a terminal regenerator of each series of regenerators re- :spectively to a terminal heatingilue of'said heating passage, idamperv means intermediate to said.A

ducts and said terminal heating ues,^a of for all of the ovens of .the battery located at the same level with and in between said sets of serial- Aiii) the time of contact and affording a more effective i heat transfera duct at each end of the oyenl conf ,Y

`ly connected regenerators, ducts. connecting the lower'chamberiike yslums of the other'terminal l regenerator of each of said series of regenerators to said transverse chimney-air nues. sir inlet ports at one end of said transverse chimney-sir flues, a waste gas stack at the other end ofl said transverse chimney-air flues, single chimney valve means for'connecting one ofsaid chimney-air4l` nues to the'chimney while at the same time disconnecting the otherchimney-air flue from the chimney, and single air valve meanscooperating with said chimney valve means fox" connecting the chimney-air i'lues disconnected from the chimney to the air-while at the same time disconnecting the other chimney-air flue from the air and automatic actuating means for said valve means for interchangeably connecting one of said transverse ilues 'with said air ports and the other 'with said stack respectively to cause the flow of adapted to be sealed against* the admission of air"- and having a sole thereunder, a plurality of longitudinai andhorizontal heating ues located in parallel-spaced position underneath the sole of iss said chamben'each of said flues being connected with the adjacent fines-on either side of it at lalternate ends of said chamber respectively to form a-serpentine heating passage, burners located",at the turns between adjacent heating nues, -a pair of sets-of regenerators below said 'heating passage, each set having one end respectively connected to one end of said heating passage and adapted alternately to preheat air and to withdraw heat from the. hot products of combustion', a pair of chimney-air flues arranged transversely to said pluralityof coke ovens and in common for all of said colse ovens connected to the other ends of said lsets of, regenerators respectively, air inlet ports at one end f said transverse fines, a waste gas stack at the other end of said transverse nues, and 'gas stack at the other end of said transversev chimney-air flues, and single chimney valve means for connecting one of said chimney-air fiues to the chimney while at the same time disconnecting the other chimney-air flue from the chimney, and single vair valve mean's cooperating with said chimney-air flue disconnected from the chimney to the air while at' the same time disconnecting vbroader than its heightl adapted to be sealed against the admission of'air and having a soie thereunder, a plurality of longitudinally extending horizontal heating -flues' located vin parallelspaced position underneath the sole of said chamber. each of sam-nues being cometen was Athe adjacent flues on either side of it at alternate ends of said chamber respectively to form a serpentine heating passage, burners located'at the turns between adjacent heating ues, a series of `regenerators connected to each end of said heatney-air flue from the chimney, and single air valve means cooperating with said chimney valve means for connecting the, chimney-air nue disconnected from the chimney to the air while at the same time disconnecting the other chimney-air ilue from the air, whereby a flow of ygases is eifected through said regenerators and said heating pas-v sage in alternating directions and whereby substantially uniform heating conditions are provided over substantially the entire sole area ofthe coking chamber.

11. In a by-product coke oven of the broad rectangular sole-tired type, 'the combination set forth in claim l0 which includes a plurality of take-ofi ducts in the roof df said coking chamben and a common gas duct in communication with said take-oi! ducts whereby the gases evolved are rapidlyremoved from the cokingI chamber vand prolonged contact of said gases with heated surfaces and consequent excessive cracking of hydrocarbons are eliminated, thereby providing an increased yield of by-products. v

l2. In a by-product coke oven of the broad rectangular sole-tired type; the combination 'set forth in claim 10 which includes`a plurality-of charging holes in the rooff'of said coking chaxnber, take-ofi ducts and a common horizontal gas duct' connected to said charging holes for rapidly removing coking gases from said oven to eliminate prolonged contact of said gases with heated surfaces and consequent excessive cracking `of hydrocarbons, an off-take pipe in vcommunication with said horizontal gas duct, and ejector means for introducing a gaseous medium under pressure' into the olf-take pipe in an upward direction to provide .an induced draft' whereby gases and smoke evolved during the charging operation can be positively removed'throughthe o'E-take pipe. 55

CHARLES H. HUGHES.

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