US2309957A - Process for coking carbonaceous material - Google Patents

Description

Feb. 2, 1943. c; H, HUGHES 2,309,957

PROCESS FOR' COKING CARBONACEOUS MATERIAL Original Filed larchl 8, 1940 3 Sheets-Sheet 1 INVENTOR CHARLES H.H UGH E5 BY c; M

ATTORNEY I Feb. 2, 1943. c. H. HUGHES PROCESS'FOR COKING CARBONACEOUS MATERIAL l3 Sheets-Sheet 2 original Filed march 8. 1940 lNvENoR CHA mes HHueHEs' BY@ ATroRNEY v Feb. 2, 1943. c. H. HUGHES 2,309,957

PROCESS FOR COKING CARBONACEOUS 'MATERIAL original Filed March 8, '1940 s sheets-sheet :s

ATTORNEY Patented Feb. 2, 1943 UNITED STATES PATENT OFFICE 2,309,957 PRGCESS FOR COKING CARBONACEOUS MATERIAL Charles H. Hughes, Glen Ridge, N. J., assignor to Hughes By-Product Coke Oven Corporation,

New York, N. Y.,

a corporation of New York Original application March 8, 1940, Serial No. 322,875. Divided and this application March l, 1941, Serial No. 381,356

z claims. (c1. 2oz-12) As those skilled in the art know, in the earliest times coke was produced in mound-shaped Meilers similar to the old method of burning charcoal inV heaps. The beehive oven was a modiiication of these except that it was built of brick instead of sod or clay, and the earliest record of coking coal in a regular oven is an English patent to St. John granted in 1620 for making coke in a beehive form of oven. Alth'ough 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. In 1781, an attempt appears to have been made to recover the by-products, and a patent to the Earl of Dundonald was issued, and in 1792 Murdoch experimented with making gas from coal in retorts. These eii'orts bore fruit, and twenty years later the streets of London were lighted by 88S.

'I'he 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 fiues, 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 to recover by-products and illuminating gas. 'I'hese 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 fire or flame passing from a grate through a central ue and then returning through ues on both sides thereof. The following year, Appolt built his first ovens in the shape of vertical and, later, horizontal retorts, using his gas only for heating his oven through horizontal flues. This was about the earliest closed retort coke oven, utilizing the gas for its own heating. By 1861 the Coppee coke oven of Belgian invention was in use on the Continent, and in 1873-74 it was introduced into England. It had vertical nues and was of the non-recovery type.

About 1862 Carves of France introduced side ues in addition to the bottom flues of Knab. About 1880, Simon, an English inventor, improved the Carves oven very materially by adding recuperating iiues. This oven had the oven ues placed horizontally, the gas and air being rst burned in sole flues located underneath the oven chamber, then passing up through a riser to the ovens and down through three horizontal ues in series. In the years 1881 to 1883, Seibel patented an oven having horizontal ues 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 rst admitted over these grates, the amount of coal Abeing such as to supply the required additional heat.

The rst ovens of the Otto type had been erected in Germany in 1881, and in the same year Huessner appropriated the Knab-Carves -model and built a hundred ovens in Germany,

thus establishing the industry on a sound basis in that country, although the quality of coke from these ovens was inferior. In these ovens the ues were horizontal. A very substantial improvement was made by Hoffman, who added the Siemens regenerator to the Otto coke oven and thus provided the first really emcient coke oven, generally referred to in the art as the Otto-Hodman coke oven. In 1888 Festner, a German inventor. changed the Otto-Hoiman design by using horizontal instead of vertical nues and abandoning the Siemens regenerators, replacing the same with a Ponsard gas furnace. Hoiman cooperated with Festner, and this design was called a Festner-Hoffman oven, having horizontal iiues and recuperators. In 1887, the Semet- Solvay oven came into notice, the rst of them having no recuperators or regenerators. It appears that some of the principal features of Semets design were the introduction of the division Wall, the 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, iiue, and, in general, providing a structure which was strong, easily heated and had reservoir of heat in the division walls.

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

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

2. The Coppee oven, with vertical ilues in the oven Walls, these ovens being built narrow, long and high.

3. The Knab broad oven, neath.

4. The Knab oven modied by Carves, with the oven lues horizontally in the side walls as well as underneath.

The high, narrow coke ovens of the prior art described in the foregoing had various important with ues under- *of a high, narrow oven was limited to certain coals or coal mixtures. Coals which expanded upony coking could only be used if mixed with shrinking coals, as otherwise the wear on the walls was too great, and the increasing pressure might have led to destruction of the ovens. Using a large percentage of shrinking coals, as necessarily became general practice, the coal shrank away from the heating walls, causing the formation between coke and wall of irregular gaps and crevices which 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 uniformly carbonized coke in a short `coking period, regardless of the method of heating or control employed.

Also, this channeling brought the rich gases into immediate contact with the highly heated refractory walls, producing two unfortunate results. First, the contact of the crude gases with some 1440 square feet of brick at the highest temperature in the oven caused the destruction of a part of the valuable by-products contained in the gases. Secondly, the gases acted as an insulator between the hot walls and the coking coal,

preventing considerable heat from reaching the -charge by conduction. Again, the gases, bing -much lower in temperature than the walls, took up considerable heat from them and thus prevented this amount of heat from reaching the core of the charge at all. Both of these effects resulted in greatly retarding the coking time and were diametrically opposed to the results desired, for it was, of course, the purpose of the operation to transfer heat from Walls to coal charge as efficiently as possible and in the shortest time. Moreover, the heating of the gases had the undesirable effect of passing the gases to the byproduct plant in a superheated state, necessitating larger condensing surfaces to cool them.

A further disadvantage of the high, narrow coke oven was that the width of the charge varied over the length of the oven, for practical reasons being smaller at the pusher end than at the coke discharge end. In order to provide for uniform coking throughout this constantly varying oven width., more gas had to be burned in the iiues at the coke end of the oven, necessitating a difference in size of heating flues over the length of the oven. This required very accurate control of the fuel gas to the individual flues.

Under these conditions, it was difllcu'lt to control heating conditions in these ovens, the oven structure was intricate and expensive, resulting in high-cost coke, and the coke produced was primarily suitable only for metallurgical purposes and not for domestic use and electrode uses. Subsequently, a broad rectangular sole-fired coke oven attempting to eliminate these disadvantages and to coke coal at a lower cost was developed, but other diiiiculties arose.

Essentially, this broad oven construction provided a rectangular sole-fired coke oven having a multiplicity of long, independent, parallel heating ilues arranged side by side, each of said flues being directly connected at each end to two shallow, horizontal hair-pin regenerators below and parallel to and individual to each separate heating flue for alternately supplying heated air to the flues and receiving the heat of waste gases' discharged therefrom. Each heating flue was provided with a burner or means'for supplying rich fue'l gas to both ends thereof. In this manner all of the flames burned in independent and `isolated fiues in the saine direction and extended from one end toward the other end of the oven. Thus, each heating flue and its associated regenerators could be alternately operated. independently of adjoining heating flues and regenerators.

Although this type of broad oven could be built in relatively small units, the entire heating system and the so-called regenerators were fundamentally incorrect. The oven was ydesigned for underring with rich coke oven gas only. The use of coke oven gas with preheated air gave a short and hot flame resulting in nonuniform heating of the long, straight, parallel and independent heating flues. An excessively high temperature occurred at each burner, producing danger points or hot spots. Moreover, the regenerators were so designed .that the waste l gas and incoming air always circulated in a horizontal direction which failed to give satisfactory and efiicient results.

In other Words, by eliminating some of the disadvantages of prior ovens, the broad oven described introduced new dimculties which were in part much more serious than the former. Thus. the ends of the heating iiues in said broad oven were overheated, causing overcoking and quick overheating of the construction material of the oven, while black spots, too cold for proper coking, developed in the centers of the flues. Clearly, it was practically impossible to obtain proper coking of the center mass except, and then to only a small extent, by overcoking the masses at the ends of the flues. Then, the space provided above and below the regenerators was inadequate for the gases to spread or mushroom out before going through the checkerbrick. Moreover, the regenerators, which were individual foreach flue, were insuiiicient in size and could not function satisfactorily. The velocity of the gases in the heating flues was too slow and in the regenerator too high for proper heat transfer. Of course, not only did this non-uniform distribution of heat greatly decrease 'the over-all emciency of these ovens, but, especially, the hot spots, developed in the operation of the oven, caused early deterioration of the building material and greatly increased the cost of operation and maintenance. The above diiiiculties were accentuated when it was desired to coke pitch of a quality suitable for carbon electrodes, carbon brushes and other articles where a high percentage of pure carbon was required. Between the years 1906 to 1923 attempts were made by coke oven builders and operators to coke pitch in by-product coke ovens. Variousspecial oven designs were tried,v without success. The principal cause of failure was due to the location of the heating iiues. All such ilues, either horizontal or vertical, were adjacent to the coking chamber. 'I'he pitch seeped through the brick Joints and lled the heating flues where it would solidify and stop the circulation. Since the year 1923, the bulk of pitch has been coked in beehive ovens in Which there are no heating nues. The coking process is to charge several tons of flake pitch into the beehive oven, ignite the pitch and after the coking process is completed remove the coked residue. In this operation about 50% of the original charge of pitch is burned to provide heat for coking. The evolved gas is conducted into a hot flue vsituated above a row of beehives Where it is burned. with a loss of all by-products. 'I'he hot waste gas from the hot flue is conducted to a waste heat boilerV for making low pressure steam.

Another diillculty associated with the coking v of pitch was foaming of the liquid pitch at certain temperatures during the coking process. Also, the charge of pitch into broad coke ovens has, of necessity, covered too large an area of the heating surface per charge, producing'` instant boiling of great intensity before the charge could be increased to the proper depth. Likewise, the flow of pitch into the oven over a large area had a chilling eii'ect on the brickwork causing some spalling contraction of the brickwork with .subsequent leakage of pitch into the heating ilues. Although these diiliculties were well known in the art, and, from time totime, various suggestions and proposals were made to eliminate them, none of these suggestions and proposals, so far as I am aware, was completely satisfactory and successful on a practical and industrial scale.

I have discovered that the outstanding problem may be solved in a simple and completely satisfactory manner.

It is an object of the present invention to provide a. process for coking carbonaceous material which eliminates the aforementioned difculties experienced in the operation of conventional broad coke ovens.

It is an other object of this invention to provide a process of coking pitch, tarry matters and coal to produce a coke substance with characteristics different from those lof coke produced heretofore by prior art processes.

Itis a further object of the invention to provide a process of coking pitch of suitable quality whereby coke for use in the manufacture of carbon electrodes, carbon brushes and other articles requiring a high percentage of pure carbon can be produced.

It is also an object of the invention to provide a coking process wherein a iiow of conbustible gases at a temperature suilicient to coke carbonaceous material is directed in a single serpentine stream beneath said material and out of contact therewith, whereby hot spots and partly undercoking and partly overcokng the carbonaceous material are avoided and whereby substantially uniform coking of said material can be obtained.

The present invention also contemplates the provision of a coking progess wherein the products of combustion are conducted in series iiow beneath the carbonaceous material in a-singlev serpentine stream and wherein additional amounts of fuel gas are burned at predetermined space intervals in said stream, whereby the presence of the combustion products prevents high heats or hot spots in the vicinity of the fuel burners and'whereby the flames therefrom are lengthened to assure proper heat transfer through the increased velocity which removes stagnant gas films.

My invention further has in contemplation the provision of a coking process wherein the direction of flow of hot gases beneath the carbonaceous material can be reversed, thereby producing uniform heating of said carbonaceous material.

The invention also provides a process wherein pitch can be added either in liquid form or in solid lump form.

Another object of my invention is to provide a process for coking pitch and tarry materials wherein steam can berintroduced for the purpose of eilectively preventing foaming.

-Moreover, my invention provides a coking process wherein a plurality of layers of carbonaceous material, can be heated by a single serpentine stream of combustible gases beneath said layers and out of contact therewith.

The invention further proposes to provide a coking process wherein carbonaceous material can be coked in two chambers in layers by heat furnished from the burning of combustible gases in a single serpentine stream therebeneath and wherein the combustible gases burned in said stream can be provided by the volatile constituents from one of the layers of carbonaceousmaterial being coked.

Still another object of my invention is to provide a process for coking carbonaceous material in a plurality of independent layers having a separate heating system for each pair of layers wherein a common air inlet duct and a common chimney flue for all of the heating systems is provided. y

'I'his invention further provides a coking process for coking carbonaceous material in a plurality of layers having a plurality of heating systems therebeneath and having a common air inlet and a common waste gas flue for all of said heating systems wherein the stack draft to each individual heating system can be individually regulated.

The invention has the additional purpose of providing a coking process wherein the fuel gas can be furnished either by the gases voiatilized from at least some of the layers of carbonaceous material or, alternatively, by atomized fuel oil or tar.

Furthermore, the invention has in view a novel process for coking pitch in broad coke ovens which eliminates the disadvantages of conventional coking processes and is capable of producing a high yield of coke of a quality suitable for carbon electrodes, carbon brushes and other articles requiring a high percentage of pure carbon.

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 horizontal plan view, having parts in section, of four broad ovens comprising eight medium-width pitch coking chambers embodying the principles of the present invention, taken on lines I-I of Figs. 2 and 3;

Fig. 2 depicts a transverse vertical sectional view taken on line 2-2 of Fig. 1;

Fig. 3 shows a vertical sectional view of a section of the chimney flue and the front; elevation of two ovens, taken on lines 3 3 of Fig. 1;

Fig. 4 illustrates a vertical, longitudinal sectional view ofA one ofthe ovens and of the regenerators taken on line 4-4 of Fig. 1;

Fig. 5 depicts a vertical section through the special L and the removable diaphragm assembly through which the volume of fuel gas to each burner is regulated;

Fig. 6 represents aperspective view of a heating system employed in a coke oven in accordance with the process of this invention, showing l combustion.

the circulation through the heating nues, regen- Verence characters denote corresponding parts erators, fuel lines, and common air inlet and waste gas outlet nues A Fig. 'l illustrates a plan view of a larger scale of a reversing dam-per incorporated into a coke oven battery in accordance with the present process; and

Fig. 8 is a vertical sectional view of the threeway reversing damper taken on line 8-8 of Fig. 7.

Broadly stated, the present invention relates to a process for coking flat layers of a carbonaceous material in coking chambers wherein they can be sealed against the admission of air. A flow of combustion gases at a temperature suilicient to coke the carbonaceous material is directed in 'a serpentine stream beneath the soles of a plurality, preferably two, of said chambers, and said flow is alternately reversed to provide substantially uniform coking of said carbonaceous material. 'I'he process can be satisfactorily carried out in a battery of rectangular broad coke ovens, each having a pair of coking chambers heated with an even number of sole ilues, preferably six, of which three flues heat each chamber and all six flues are interconnected with a seventh or circulation flue in series. While the shape of this seventh flue is not important, it must have approximately the same cross-sectional area as each of the heating flues. For structural reasons, however, it is preferred to Imake the seventh flue narrow and high, as a flue of such shape can` be fitted into a wall between header brick without having to cut the brick. The heating system common to two coking chambers and the circulation flue are connected by openings located at opposite ends, with two sets of vertical regenerators located below and parallel to the heating flues of the oven. These two sets of regenerators are alternately used to supply preheated air to opposite ends of the series ilue heating system and to receive the hot waste products of The regenerators have spacious chamber-like passages, both above and below the checkerbrick, giving the gases and air an opportunity to spread or mushroom out before passing through the regenerators. This spreading out Of the gases greatly increases the time of contact, and provides the proper contact time fo1` efficient heat transfer. The regenerators also incorporate the correct principle of heat exchange according to which a gas which is being heated must ascend through the checkerbricks, while the gas which is being cooled must descend, if uniformity of flow and high heat transfer eiliciency is to .be attained. Burners are arranged at the turning points of adjoining sole flues which may be operated by either rich fuel gas or fuel oil or tar for underflring the ovens, I also provide transverse or chimney ues in common for the complete battery of `coke ovens, these transverse flues being arranged side by side transversely of the ovens and are used alternately for w-aste gas and air. This arrangement keeps all the ilues within the oven structure in a simple, efiicient and compact form. 'I'he waste gas iiues in common for all ovens are provided at one of their ends -with a three-way reversing valve for periodically reversing the flow of air and waste gas in accordance with conventional regenerator practice.

A coke oven suitable for carrying out the process of the invention will now be more fully described to those skilled in the art, reference being had to the accompanying drawings illustrating a preferred embodiment thereof. Similar refthroughout the various figures.

Referring now more specifically to Figs. l to 4; it will be readily observed that 'the oven battery of my invention comprises a plurality of domed, rectangular coking chambers H-I of mediumwidth and arranged in pairs. Each of these coking chambers has charging holes or ports H in their roofs, adapted to be sealed by covers N. An off-take duct O--I is positioned near the top of each charging hole and communicates with the common gas duct C-I, which is located along the longitudinal axis of the oven rooi'. This common gas duct connects into an oil-take pipe M near the coke charge end of the oven. An ejector J-I connected with the steam or gas line is located in the oir-take pipe, and a valve V-Z'I on said line is adapted to admit steam or gas under pressure to the ejector. I'he coking chambers are adapted to be sealed against the admission of air by oven doors W-I and W-Z at either end of each oven. There is a small door W-3 in the pusher side oven door W-3 through which a levelling ram K may .be introduced, when necessary.

Beneath each pair of these chambers and running parallel to the length of the oven, heating ilues 2, 3, 4, 5, 6 and 1 are arranged in horizontal position, three such heating flues being provided in the sole of each oven. These sole ues are series-connected, being separated from each other by longitudinal partition walls alternately spaced from opposite ends of the ovens to form a turnbetween adjacent flues. In addition, a seventh circulation ue I is provided between each pair of ovens in the division walls thereof. The purpose of this seventh flue is to complete the circulation to the opposite ends of the two sets of regenerators. The interconnected heating ilues I to 1 are provided at the turns with burning means, such as gas burners A, A-I, A-2, B-.I and B-2 which are supplied with iiuid fuel, as 1t will be described more fully hereinafter. Below the heating ues in each pair of ovens are located two series-connected sets of regenerators R-l, BP2, R-a and R-l, RFS., R'6, built or standard checkerbrick or special checkerbrick in the usual manner. Regenerators R-I, R-Z and R-3 are connected in series with flue 1 and the transverse flue C-I common to the entire battery by passages P-I to P-I I inclusive (see also Fig. 6). Regenerators R-I, R-5 and R-6 are similarly connected with flue I and transverse flue C-Z by passages P-I2 to P-22 inclusive. Flues C-I and C-Z are preferably located on the same horizontal level as the regenerators and separate the two sets. They are adapted to serve all the ovens in the battery as manifolds for air to -be preheated in the regenerators or for waste gas to be discharged to the stack. The alternate flow of air and waste gas and the circulation through the heating nues, regenerators and said common transverse ilues are controlled by a three-way reversing damper D-3. This reversing damper is mounted in a reversing damper casing C-3. Transverse flue C-I ends in an opening V3, transverse ues C-Z ends in an opening V,5, and a similar opening V-I connects to stack S. In the illustrated position of the threeway reversing damper, the air to be preheated enters transverse or chimney nue C-Z through open slots V-S and V-S, the reversing damper D-3 being shifted to connected openings V-S and V-I.

P-ll, which lie above the checkerbrick in regenerators R-I, 'Rf-2. R-l and R-l. R-I.

I R-S, respectively (see, especially, Fig. 2),- are spacious, chamber-like and, when these regenerators are being used for waste combustion products, they are adapted to give these waste gases au opportunity to spread or mushroom out befurnish an opportunity for air flowing to the regenerators to spread and mushroom out before its upward passage through said regenerators.

'I'he terminal ilues 1 and I, of the series-nue heating system are connected through passages P--I and P-22, respectively, with regenerators R-I and R-I. The openings or ports V-l and V2 from said ues. respectively, into said passages are respectively controlled by dampers D-I and D-2, adapted to slide over said ports and to effect partial or complete closure, thus providing regulation of the draft in each individual oven.

Fuel gas manifolds F-l and F-2 (see Fig. 4) run along the length of the oven battery on opposite sides thereof and are adapted to supply burners A, A-I, A-Z and B, B-I, B-Z of each oven with rich fuel gas under a moderate and constant pressure. Riser pipes G-I and G-2 from the supply manifolds to the burners are provided and a special L and orifices are also furnished for the regulation of the fuel gas conducted therethrough. This L depicted in Fig. 5 is equipped with a plug T-I and with a removable orifice member T-2 which is adapted to be replaced by other similar members having larger or smaller orifices as required. Valves V-1,.V-8, V-9 and V-I0, V-Il, V-IZ (see Fig. 6), located in the riser pipes from the supply manifolds to burners A, A-|, A-2 and B, B-l, B-2, respectively, are adapted to shut off the gas supply entirely.

Pipe lines L-l and L2, adapted for carrying fuel oil or tar, also run the length of the oven battery on opposite sides thereof. They are connected with'burners A, A,-I, A-Z and'B, B-I, B-2 through valves V-I3, V|4, V-I5, and V-IIB, V-Il, V-IB, respectively, said valves being adapted to atomize the oil or tar. Air lines L-5 and L-6, running the length of the battery in association with the pipe lines, are also provided and connect into valves V-I 3, V-I4, V-I 5 and V|6, V-|l, V-IB through air regulating valves V-I9, V20, V-2I, and V22, V23, V-24, respectively, and are adapted to furnish air for said atomization.

The supply pipe L-3, running transversely across the complete battery of ovens, is provided for supplying the liquid pitch to be coked through pipe L-il, the ow of pitch being controlled by means of a valve V25. Steam to prevent foaming of the pitch in the oven may be admitted through valve V-26 and pipe L-4 into the cokng chamber. (Figs. 1, 2 and 4).

In the operation of the oven as an entire unit, oven doors W-I and W-2 are closed and sealed airtight, as may be seen from Fig. 4. Liquid pitch in the coking chamber, it is admitted througlf a valve V-26 and pipe L-4 into said chamber. When flake or lump pitch or coal are used, they are charged through charging holes 75 H in the top of the ovens. The flake or lump pitch, when heated, will become plastic' and willl now to a uniform depth during eoking. 0n the other hand, if coal,is charged, the cone-shaped piles are leveled oi! in the usual manner by a leveling ram K introduced through a small door W--3 in the pusher side oven door W-2. 'I'he chargingcovers N are replaced and sealed airtight. Fuel gas. fuel oil or tar is then burned with preheated air in the heating nues underneath the coking chambers to provide a uniform coking temperature for the entire area of the oven sole upon which the coal charge is supported. Asiswellknowntothoseskilledinl 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 readily understand, and a reversal period of about 15 minutes has been found to give satisfactory results when underiiring with rich fuel gas, fuel oil or tar and using preheated air to effect the combustion. When the coking process is nn; ished, oven doors W-l and W-2 are removed, and the coke is pushed in the customary manner. 'I'he gases evolved during coking rise up through charging holes H and pass through off-take ducts O-I into the common gas duct C-I, where all the gases evolved in the ovens merge into a single stream. A gas olf-take M is provided at the end of each oven and from there to the by-product plant. In this manner, the gases evolved are rapidly removed from the coking chamber, thus avoiding prolonged contact of said gases with heated surfaces and consequently excessive cracking of hydrocarbons is effectively prevented and an increased amount of light oil and tar is produced when coking coal.

An ejector J-I, located in gas off-take pipe N, is employed to suck the evolved gases to the olf-take pipe. This ejector is used only during charging operation. Steam or gas under pressure is admitted through valve V21. 'I'he flow' of the steam or gas in an upward direction draws into the off-take pipe the gas and smoke during the charging of the coal through the charging holes H. Without this induced draft some of the evolved gases could escape into the atmosphere due to the removal of the charging coal covers N. The action of the ejector in drawing these gases into the off-take pipe prevents a smoke nuisance during charging.

The operation of this improved broad coke oven will now be described particularly in conjunction with Fig. 6, which illustrates diagrammatically the flow of gases through the several fines, ducts, regenerators, dampers and valves, for the convenience of those skilled in the coke oven art. It has been pointed out in the foregoing, that this improved oven is adapted to burn both rich fuel gas and liquid fuels. The fuel gas is conducted at a moderate and constant pressure through supply manifolds F-I and F-2 into risers G-l and G-Z. Its supply to the burners is regulated through a special L conveniently located, as described before, in each of the risers. When fuel oil or tar are used instead of rich fuel gas for underring the ovens, gas valves V-l to V-i2, inclusive, are closed. The oil or tar from pipe lines L-I and L-Z illows into valves V--l3 to V-Il, inclusive, and air isalso supplied to these valves from air. lines L-'5 and L-B. The air serves to atomize the liquid fuel, which then passes to the burners. The volume of air for vaporizing said liquid fuel is regulatedV by means of valves V-IQ to V-24, inclusive.

Assuming that regenerators R-I, R-2 and .lt-3 are being preheated. damper slots V-I, V-2, V-3 and V-4 are open, permitting a flow of waste gas to chimney flue C-l and stack S. The air to be preheated enters chimney flue C-2, through open slots'V-i and V--S in the reversing damper casing C-3, the reversing damper D-3 being shifted to the position in which openings V-3 and V-I are connected. A

The air flows from chimney flue C-Z into passage P|2 or regenerator R--G which is large enough to permit the air to mushroom out, and then uniformly up through the hot checkerbrick to passage P|3. From here, by passages P-M and P-I 5, the now partially heated air is brought vv,to a spacious passage P-IS below regenerator R-5. It then flows in a similar manner through the regenerators R- and R-4 through flue P-22 to heating flue l. The preheated air for combustion of the fuel gas or vaporized fuel oil at the burners is delivered in flue l in great excess over the air required for burner A. After the combustion at burner A, the air in considerable excess of the requirements of the next burner in the series passes mixed with the products of combustion to burner B and similarly to all burners successively. The hot waste gases of combustion pass out of the series flue heating system from flue 1 through passage P-I to passage P-2 above regenerator RI. Passage P-2 is sumt ciently large for the gases to spread uniformly and then downward relatively slowly through regenerator R-l to passage P-3 below regenerator R.-I, and then successively through passages P-4 to P-II and regenerators R-Z and R-3 and into chimney flue C-l It will be noted that flue 1 is located in the wall between the adjoining pairs of coking chambers whereby the side walls of such chambers are likewise heated and prevents chilling ofthe tarry materials to be coked. In addition, the object of the provision of the seventh flue, is to complete the circulation `of heating gases to the opposite ends of the two sets of regenerators.

Upon a reversal of the draft accomplished as described above with a preheated air entering at the pusher end of flue 1, the names of burner B-2, B-I and B are deflected into nues 6, l and 2 respectively, and ames of burner A2, A-I and A are deflected into flues 5, 3 andl I, respectively. In this case, the flames burn at the pusher ends of ues 5, 3 and I and at the coke end of nues 6, 4 and 2 so that the effect of each individual flue upon the oven is just opposite to that described in the foregoing. The cumulative or additive effect of the whole series of fiues beneath the oven, however, is the same on both reversals. The heat throughout the full cycle is uniform for the entire oven. l

The reversal of the flames being deected alternately from one nue into another, mixed with the products of combustion, eliminates the danger of hot spots when regenerators Rf-I, R-Z and R-3 are raised to the temperature for `preheating the air. The direction of flow of the air and waste gases is` reversed by shifting damper D3 to cover valve .openings V-I and V-5 and to leave valve opening V-3 open for the admission of air to c ey ue C-I. `Air then enters chimney flue C-I through passage R-3, Rf-Z and R-I to heating flue 1. Stack.

draft or an induced draft fan is used for drawing air into the regenerators and for removing the gases of combustion. The stack draft for each heating system of seven flues is regulated by the position of slide damper D-I over opening V--I and damper D.-2 over opening V-2. In the operation of the two chambers heated by a single common heating system, it is not necessary to charge the pitchor coal into the two chambers simultaneously, as each chamber, having separate charging means and individual doors, can be operated upon an independent schedule.

After the pitch or coal is coked, oven doors W-l and W-2 are removed and the coke is pushed in the customary manner.

It will be noted that the broad coke ovens embodying the process of my invention provide various important advantages. Due to the fact that the heating flues are placed under the floor of the oven, any pitch seeping into these ilues will be quickly burned in the presence of the burning fuel gas. Any unburned carbon or carbon ash can be raked or blown out by removing the panel wall at the ends of the heating fiues. The walls separating each heating flue extend to the face of the outside wall, and each end panel can be removed without disturbing the adjoining brickwork whereby inspection and maintenance of the heating iiues is greatly facilitated,

It is also to be observed that, in the closed type coking chamber employed in the present process, none of the pitch charged into the closed oven chamber is burned as in the conventional Aof operation are obtained.

Those skilled in the art will appreciate that the present invention provides a novel and improved process for coking pitch. As a result of the fiat oven floor, a pitch coke of uniform thickness is produced. All pitch is charged into the oven quickly. The mass starts coking uniformly oven the entire oven floor area insuring a uniformly dense coke. Either liquid, flake or lump pitch can be charged into the oven and foaming of the pitch is prevented by admitting steam into the coking chamber.

Furthermore, the present invention makes it possible to coke carbonaceous material in a pair of coking chambers with the use of a heating system common to both chambers. If the vol. ume .of gas evolved from the pitch is not sufficient for underring, then coal can be coked in one chamber to provide sufficient gas, while the other chamber can be used for coking pitch. In contrast to the conventional coking ovens employed in prior art coking processes, the ,fuel gas burns constantly in the heating ues under the oor of the coke ovens which I have described as suitable for carrying out the process of the present invention, and the flames change direction only upon reversal, means being provided for regulating the volume of gas separately to each burner.

Although the present invention has been disclosed in connection with a preferred oven construction for carrying out the same, variations and modifications of this construction may be resorted t0 by those skilled 1n the art Without departing from the principles of the present invention. I consider all of these variations and modiiications as within the true spirit and scope of the present invention as disclosed in the foregoing description and dened by the appended claims.

The present application is a division of my copending application Serial No. 322,875, led

,March 8, 1940, and entitled Broad coke ovens.

now Patent No. 2,259,380.

I claim:

l. 'I'he process of coking pitch in a long rec-l tangular oven broader than its height and having a pair of combined coking chambers. which comprises introducing pitch into one chamber of said pair of combined coking chambers; spreading said pitch onto the sole of the coking cham- .ber in a layer that is thinner than its width and length; introducing coal into the other coking chamber; sealing said oven against the admission of air; establishing under the soles of said pair of combined coking chambers and 1ongitudinally thereof, a ow of hot combustion gases to furnish heat at a temperature sufilcient to coke the coal and the pitch; changing the direction of said ilow of hot combustion gases v of hot combustion gases, whereby uniform heating conditions over substantially the total area of the soles of said pair of combinedcoking chambers can be attained, and whereby hot spots and partly overcoking and'partly undercoking the pitch and the coal on the soles of said pair of combined coking chambers are avoided; continuing said alternate reversals until the entire volume ofthe layer of pitch is fully coked; removing at least a portion of the volatile constituents of the coal from the coking chamber wherein the coal is contained; and conducting said volatile constituents beneath thevsoles of the pair of combined cokingl chambers to provide t e hot combustion gases for coking the pitch and the coal, whereby the pitch is coked substantially uniformly.

2. The process-of coking pitch in ia plurality of long rectangular ovens broader than their height and in which each of said ovens has a pair of combined coking chambers, which comprises introducing pitch into a chamber of each i of vsaid pairs of combined coking chambers; spreading said pitch onto the soles of the coking chambers in layers that are thinner than their other coking chambers; sealing said ovens against the admission of air; establishing a main stream oi' combustion air for the plurality of ovens; dividing said main stream into a plurality of individual streams of combustion air foreach oven; streams of combustion air: introducing under v width and length; introducing coal into the preheating said individualthe soles of the pair or combined coking chambers in each oven and longitudinally thereof,

the plurality of preheated individual streams of combustion Aair, said preheated individual 'streams of combustion air being substantially parallel and having their ends at predetermined space intervals transversely with respect to said pair of combined coking chambers; alternately changing the direction of ilow of preheated combustion air in said plurality of substantially parallel individual streams of preheated combustion air under the soles of said pair of combined coking chambers to provide substantially parallel individual streams in which preheated combustion air flows in opposite directions in adjacent streams; alternately uniting the ends of adjacent streams of preheated combustion air to combine the ow of preheated combustion air in said plurality of individual streams of preheated combustion air into a single and continuous serpentine stream of preheated comlbustion air under substantially the total area of the soles of said pair of combined coking bustion air, whereby the direction of iiow of preheated combustion air in said adjacent streams will determine the stream in which the fluid fuel will flow; burning said iiuid fuel in said 4plurality of substantially parallel individual streams of preheated combustion air un. der the soles of said pair of combined coking chambers to propagate therewith a plurality of ames alternately traveling in opposite directions in said individual streams to furnish heat to the soles of said pair of combined coking chambers in each oven at a temperature sumcient to coke the pitch and the coal thereon;

introducing steam into thecoking chambers containing pitch to prevent foaming of said pitch; withdrawing and storing heat from said individual streams; reuniting said individual streams y and partly undercoking the pitch and the coal on the soles of said pairs of combined coking chambers are avoided; continuing said alternate reversals until the entire volume of the layers of pitch is fully coked; removing at least a portion of the volatile constituents of the coal from the coking chambers wherein th coal is contained; and conducting said volatile constituents beneath the soles of each pair of combined Y coking chambers in the plurality oi' ovens to provide the uid fuel for coking the pitch and the coal on the soles of the pairs of combined ,coking chambers, whereby pitch is coked substantially uniformly. l CHARLES H. HUGHES.

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