US2410074A - Apparatus for pyrolytically treating hydrocarbons - Google Patents

Description

Oct. 29, 1946. HUGHES 2,410,074

APPARATUS FOR PYRQLYTIGALLY TREATING HYDRocARBoNs Filed Nov. 18, 1945 4 Sheets-Sheet l M5775' GAS ATTORNEY a. @Sumn- Oct. 29, 1946. Q H HUGHES 2,410,074

APPARATUS FOR PYROLYTICALLY TREATING HYDROCARBONS FledNQV. 18, 1945 '4 ShetS-Sheet INVEN'ToR CHA fPL Es, HH uc; Hfs

ATTORNEY Oct. 29, 1946. C. H. HUGHES 2,410,074

.PPARATUSFOR PYROLYTICALLY TREATING HYDROCARBONS Filed NOV. 18, 1945 4 Sheets-Sheet 4 l BYG" @t ATTORNEY Patented Oct. 29, 1946 APPARATUS FOR PYROLYTICALLY TREATING HYDROCARBONS Charles H. Hughes, Glen Ridge, N. J., assignor to Hughes By-Product Coke Oven Corporation, New York, N. Y., a corporation of New York Application November 18, 1943, Serial No. 510,760

(Cl. 19E-104) '7 Claims.

The present invention relates to a method of pyrolytically treating hydrocarbons to cause the conversion thereof, and, more particularly, to a method of pyrolytically treating in a broad cracking and coking oven straight chain hydrocarbons, like paraffin hydrocarbons occurring in petroleum and the like, to convert them into aromatic hydrocarbons, such as benzol, toluol, Xylol, naphthalene,V anthracene, and the like, While evolving vapors containing straightl chain hydrocarbons from a fluid hydrocarbon mass and carbonizing the residue thereof into coke, and to an improved cracking and coking oven to carry the aforesaid methods into practice.

Heretofore, various methods have been used in converting one hydrocarbon into another. Generally speaking, such conversions were conducted ina variety of metal equipment, including stills, cracking units, etc., etc. In recent years, attempts have been made to conduct the pyrolytic conversion of hydrocarbons in ovens, such vas coking ovens oi the broad type. Various diiiiculties were encountered and unsuccessful resuits Were obtained, including failures in certain instances. The most serious diiculties were the choking-up of channels and conduits with carbon, soot, and the like, the production of lovv yields of aromatic hydrocarbons, the poor coking of the residue of fluid hydrocarbon masses, and the 10W grade and bad quality of coke which was pro duced. In attempts at actual commercial operations of the pyrolytic conversion of hydrocarbons on a commercial scale, the results were so bad that the operations were given up as commercially unadvisable and were considered as industrial failures. Although various endeavors were made to overcome the foregoing difficulties, none, so far as I am aware, has been wholly satisfactory for commercial operation conducted on an industrial scale. f

The present invention involves the discovery that in cracking-hydrocarbon vapors evolved during the coking of petroleum residues, fory instance, for the production of aromatic hydrocarbons, it` is necessary to control not only the direction ofi flow of the vapors and the temperature of the cracking fluids, but also the space velocity'and the turbulence of the vapors. It has likewise been discovered that a cracking oven, having a special structure, must be provided in order to properly` carry out the pyrolytic conversion of hydrocarbons while at the same time heating fluid hydrocarbon masses tc evolve hydrocarbon vaporsL and to carbonize the 'residue into good coke having acceptable qualities and properties.

It is an object of the present invention to provide a method for the pyrolytic conversion of hydrocarbons commercially and on an industrial scale with yields high enough to makev it economical to carry the process into practice on a commercial scale. with resulting benefits to the public generally and to industry specifically.

It is another object, of the invention to provide a process for the cracking of straight chain hydrocarbons and their conversion into aromatic hydrocarbons with high enough yields to Warrant industrial operation.

Furthermore, the invention contemplates the provision of a vapor cracking oven having a special structure which is capable of heating a fluid hydrocarbon mass to evolve hydrocarbon vapors therefrom and to carbonize the residue into coke, thereby effecting the pyrolytic treatment of the evolved vaporsy containing straight chain hydrocarbons and their conversion into aromatic hydrocarbons, such as benzol, toluol, Xylol, naphthalene and anthracene, and the like.

Moreover, the invention likewise contemplates the provision of a cracking and broad coking oven in which the tar and carbon resulting from the pyrolytic treatment of hydrocarbons can be made into a high carbon coke having a true specific gravity of 2 plus and suitable for the manufacturing of carbon electrodes.

It is still a further object of the invention to provide a cracking and coking oven of novel and improved design providing a heating system for the distillation of heavy Ipetroleum and also a separate heating system within the same oven structure for the cracking of the oil vapors and the pyrolysis of parafns for the production of aromatic oils and` other aromatic hydrocarbons.

It is also an object of the invention to provide an improved broad cracking and coking oven having the Walls of the vapor flues constructed with uneven surfaces to produce turbulence of the cil vapors in such a manner as to cause the oil vapors to contact the hot wall surfaces, whereby eiective pyrolytic treatment of hydrocarbons can be conducted.

4 ItV is Within the contemplation of the invention to provide a cracking and coking oven of novel and improved character providing an increased and positive control of the flow and velocity oi the oil vapors' through the vapor lues, an increased and positive control of the air to be preheated and of the Waste gas from the oven, and an arrangement of structural elements capable of causing the air Whichis' being heated to ascend and of causing the waste gas which is being cooled to descend, whereby uniformity of ow and an effective change of temperature of the different streams are obtained.

The invention also provides a broad cracking and coking oven having a series o-f interdependent and interconnected heating ues extending in a single continuous, serpentine character under the entire sole of the oven to afford a continuous stream of the heating gases throughout the whole sole flue heating system and having a multiplicity of ,burners in the series fiues to furnish a continuous flow of hot gases throughout whereby uniform heating conditions in all parts of the oil charge are obtained.

Another object of the invention is to provide an improved cracking and coking oven having a system of heating flues so designed as to conduct the products of combustion to each succeeding flue in series for the purpose of using said waste products to prevent high heats or hot spots in the vicinity of the fuel burners and to lengthen the name by means of the increased velocity necessary for proper heat transfer, the increased velocity being due to the increased volume of gases constantly circulating through all heating flues.

A further object of the invention is to provide a cracking and coking oven in which the direction of ow of the hot gases through the heating flue system can be reversed, thereby insuring' uniform heating over the entire floor of the oven.

The invention likewise contemplates the provision of an arrangement of gas burners in the new cracking and coking ovens in such positions 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 ues, moving back and forth from one heating flue to another adjacent flue.

Still further objects of the invention are the provision of an independent upper `heating sys,

tem associated with the roof of the oven and consisting of a multiplicity of separate heating flues disposed horizontally, transverse to the oven and oil vapor flues, for providing the controlled heat required for pyrolytically treating the hydrocarbons in the oil vapors flowing through the super-imposed vapor flues; of a gas or oil burner at the end of each separate ilue so as to control the transfer of heat to the oil vapors as required in various sections of the vapor cracking flues; and of refractory materials best suited for rapid heat transfer, such as silicon carbide, for the ocr of the overland the oor of the oil vapor flues and other super-duty high temperature refractory materials impervious to the infiltration of oil or tar, such as refractories made of diaspore, mullite, cyanite, or the like.

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

Fig. 1 illustrates a vertical cross-sectional View of one oven showing the vertical regenerators, lower and upper heating systems, flues in which the oil vapors are cracked, the gas and air supply manifolds and piping to the upper transverse heating system and the air and oil ports leading into the oven;

Fig. 2 depicts a vertical longitudinal sectional view of one oven, regenerators, lower and upper heating flues, vapor flues and regulating dampers in said vapor ilues for controlling the ilow of the vapors;

Fig. 3 is a sectional View taken on the line 3-3 of Fig. 2 showing the series flue heating system located directly under the door of the oven;

Fig. 4. is a sectional View taken on the line @-4 of Fig. 2 illustrating the longitudinal uneven walls forming the ilues through which the vapors flow and are heat treated and cracked;

Fig. 5 is a sectional view taken on the line 5-5 of Fig. 2 and shows the upper transverse heating system located above the coking chamber and directly under the vapor iiues, shown in Fig. fi;

Fig. 6 is a plan section of the nues taken on the line 6 5 of Fig. 2 directly below the regenerator checker-brick to show the iiow of waste gas and incoming air to and from the vertical re generators;

Fig. 7 is a perspective showing a line diagram of the upper and lower heating systems, regenerators, gas piping, stacks and the Isley system for reversing the air through the regenerators and lower heating iiues and the travel of the exit waste gases through the Isley ejector to the atmosphere; and

Fig. 8 is a sectional view of the special L and orifice provided for the regulation of fuel gas.

Broadly stated, the present invention contemplates the pyrolytic conversion of hydrocarbons, such as the production of aromatic hydrocarbons from hydrocarbon vapors evolved from the heating of petroleum residues and the like. By controlling the direction of flow of the vapors in the oven and through the cracking chamber and the control of temperatures in the cracking chamber while at the same time controlling the space velocity and turbulence of the vapors, relatively high yields of aromatic hydrocarbons, such as benzol, toluol, and Xylol, are accomplished. In carrying the foregoing operation into practice, large quantities of gases are produced from the petroleum residue or the like, under treatment, as Well as tar and carbon, which are converted into useful coke. All of the foregoing operations are conducted in a single structure having cooperating elements which reduces the cost of manufacture and eliminates the operating difficulties of prior operations. Good results and high yields of aromatic hydrocarbons and electrode coke can be obtained from the processing of, for instance, a low grade A. P. I. cracked petroleum residue which is charged into the cracking oven at 700 F. The single structure involves abroad cracking and coking oven with a heating system adapted to operate with either rich fuel gas, such as coke oven gas, oil gas, or with liquid fuels, such as fuel oils, tars, and the like, combined with a heat regenerative system. Housed within the upper part of the oven is a cracking chamber provided with an independent heating system which can be so controlled as to obtain the desired temperature in the walls of the cracking oven. The entire brick work can be encased in a metal shell, such as a welded or riveted steel casing, whereby the interior of the oven can be put under pressure or under vacuum as desired.

Generally speaking, the oven heating system preferably consists of an uneven number of sole nues, say three, ve, seven, or nine interconnected in series and arranged longitudinally of the oven to support and heat the floor of said oven. These heating flues are connected to damper controlled ports or openings, located at opposite ends of the series, with two sets of vertical regenerators located below and parallel to the heating ilues and ovens.A The two sets of vertical regenerators are alternately usedto supply pre-heated air to opposite ends of the series flue heating system and to receive the hot waste products of combustion. The regenerators, of which I prefer to employ three, are connected "in series in eachset, have spacious, chamber-like passages both above and belowr the che'ckerbrick,

giving4 the gases an opportunity to spread or y cracking and heat treating the vapors for theL production of aromatics and for the conversion of hydrocarbons. f

For the purpose of giving those skilled in the art a better understanding of the invention, a detailed description will be given in conjunction with the drawings.

Referring now more particularly to Figures l to 6, it is Vreadily observed that the cracking and colring oven embodying my invention is a domed rectangular broad coking chamberv l-I-l, in which the fluid hydrocarbon mass, such as oil residue, tar or the like, is treated and is distiled. superimposed upon the chamber are flues I-I-l in which vapors from the mass of fluid hydrocarbons, such as hot oil residue or tar, are treated. The hot oil or hot tar is charged into the coking chamber H--l, through charging hole ports H-2, in both sides of side walls of the oven. rThe oil vapors pass from the coking chamber H-l, 'through olf-take duct D, into the vapor heat treating lues H-lL and out of the oven structure through flue lil-5 to ley-product recovery apparatus; In cerinstances, it may be desirable to take off the uncracked vapors `through offftake flue H-, is provided with a damper D-S, similar to' D--5, which is shown in Fig. vl and is illustrated diagrammatically in Fig.' 7. The coking mber l-l-l is adapted to be sealed against the admission of air by oven doors K-l, which e provided at the pusher end and the discharge end of the oven.

Beneath each colring chamber and running parallel to the length thereof, heatingues l, 2, land 5 are preferably arranged in horizontal position and are preferably series-connected. The flues are separated from each other by 1ongitudinal partition walls alternately spaced from opposite ends of the ovens to form a turn between adjacent flues. The interconnected heating flues are provided at said turns with burning means, such as gas burners B--!. B-f, B-3 and B-e, which can be supplied with fuel, as will be described hereinafter. f

Below the heating ilues of each cracking and coking oven are located two series-connected sets of regenerators R-i, R-Z, Re?, and R-el, idf-5, R6. The regenerators are huilt of standard checkerbrick or special checkerbrick in a conventional manner. Regenerators R-l, BMZ and R-3 are connected with flue 5 and transverse ue C-L lay-passages P-l to PY-ll inclusive (see Fig. 7). Regenerators R415-, 1%;5, and R-l keratorsY and separate the tw'o sets.

6 are similarly connected with ue l and transverse ilue C2 and by-passages P-lf' to P-22 in-A elusive. cated on the same horizontal level as the regen- They are adapted to serve as' manifolds for'air to be preheated in the regenerators or for waste gas to be discharged to the stack through the Isley system. The alternate flow of air and waste gas and the circulation through the heating ues, regenerators and said common transverse'r ilues are controlled by reversing and plate dempers of the Isley system connected with flues C-2 and C-l, which are connected with heating flues l and 5, respectively, by passages P-l2 and P-l leading to regenerators R-ll and R-l, respectively, vas will be more fully explained hereinafter.

Passages 13 2, PL-B, P-ill, and P-l, P-VI'P, and P-2l, which lie above the checkerbricl: in R-i, Rw?, Re-3, and R-'ll, R-, R-, respectively (see Fig. 7 andv Fig. `2) are spacious and chamber-like and, when these regenerators are being used for waste combustion products, they are adapted to give these Waste gases an opportunity to spread or mushroom out before passing downwardly through said regenerators. Similarly, passages P-S, P-l, P-ll and i3-lt P-i t, P-`22, which lie below the checkerbricl: in said respective regenerators, are also spacious and chambenlike 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 ihof the series hue heating system are connected through P-l and i3-l2, respectively, with-regenerators R-l and R-4. The openings or ports V-i and V-2 from said fines, respectively, into said .passages are respectively controlled by dampers D-l and D,-l?, 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. 2) run the entire length of one or more ovens on opposite sides thereof and are adapted tosupply burners B-l, B--2, B-k-l, and B-d of each oven with rich fuel gas under moderate constant pressure. Riser pipes G--l andCifrom the 'supply manifolds to the burners are provided, and

a special L orifice are also furnished for the regulation of the fuel gas conducted there through. This L, depicted in Fig. S, is equipped with a plug T--l and a removable orifice T-2, which is adapted to be replaced by other similar members having larger or smaller orifices as re quired. Valves l-3, V-il, V-li and V-li (see 7 and 2'), located the riser pipes from the manifolds to burners B-l B- 2, B-3 and B-ll, respectivelyare adapted to shut olf the gas supply entirely. l

For certain conditions, an auxiliary fuel supply can be easily added by the use ofv pipe lines L-I and L--2 (seeFig), adapted for carrying fuel oil or tar, also run the length of the oven or 'ovens Von opposite sides thereof. They are connected with burners B-l, 3 2, B-3 and B-e through'valves V-`l, V-, V9 and V--l@, respectively, said valves being adapted to atomize the oil or tar. Air lines lr-S and L -Ll running the length of the oven yin association with the pipe lines are also provided connect with valves V-l, V-B, VMS and V-l, through air regulating valves V-i l, V--i2, V-ES and V-M, respectively, and are adapted to furnish air for said atomization.

Flues C+! and C--Z are preferably loy The foregoing description of the lower half of the entire unit is used primarily for the distillation of oil or tar. The following description covers the upper part of the oven in which the oil or tar vapors are cracked` and where the method of pyroiytically treating hydrocarbons for the production of aromatic oils takes place. The two oven sections form and are operated as one unit.

The upper section of the oven structure embodies a heating system and oil vapor cracking, heat-treating fiues,

The heat treating flues H-i (see Figs. 2, l, and 7) which may consist of any number of flues as required lto handle the volume and velocity of the oil vapors, are arranged in a horizontal position and are separated from each other by longitudinal partition Walls W. Each wall has a multiplicity of projections W-l. The purpose of the projections is to cause turbulence of the oil vapors, causing them to contact the hot wall surfaces.

Each vapor flue H-c is provided with regulating dampers D-3 and D-d (see Figs. l, 2, and 4) for the purpose of controlling the volume of gas from duct D to exit ue H--5- Beneath the vapor flues H-4 (see Figs. 2, 5, and 7) and located transversely to ues H--li are heating iiues 5. These heating flues 6 are single and separated by partition walls W-Z. Y

Each heating flue has a separate gas burner B-E supplied with fuel gas from gas manifold F-3 (see Figs. l and 5). The air for combustion is supplied from air manifold pipe F--S through air pipes F-l. The products of combustion from all of the heating ues 6 discharge into ue 'l (see Figs. l and 5) and to the stack through flue 8.

When oil and tar vapors from the charge have all been evolved and there are no vapors to heat treatin fiues H-, then the carbonaceous residue has been thoroughly coli-.ed and the coke is ready to be calcined for the purpose of improving the true specic gravity of the coke Ito meet electrode specifications, if so required.

Coke is calcined by means of forcing either hot or cold air in and around the coke to produce limited combustion which burns all remaining oil, volatile matter and loose carbon particles. The local combustion produces a hard dense cell wail structure which increases the specific gravity of the coke from an average specific gravity of about 1.8 to about 2 plus.

In my invention I have discovered that preheated air reduces the time of calcining the coke. I preferably preheat the air for calcining in ues H- (see Figs. l, 2,5 and '7).

Damper D-5 located between vapor flues H-4 and the by-p-roduct recovery equipment is closed. Damper D-e in air pipe 9 is opened. The lair to be preheated hows through pipe 9 into the distributing flue H-5y then through vapor flues H-li, where it is preheated from heating ilues E.

The preheated air for combustion enters the oven H-l through duct D. The small volume of products of combustion resulting from the preheated air burning some of the coke, then enter duct H-'l (see Figs. 2, 5, and 7) and pass to a stack through open damper D-l.

During the coking of tar, some carbon is deposited over certain areas of the oven oor; to burn this carbon air as required is introduced (see TEigs. l and 2) lthrough air ports H-3 from pipe F-S into oven chamber CEI-I.

The transverse flues C-I and C-2, referred to in the foregoing as being used alternately for 'air-,and waste gas, are communicably connected with the Isley induced draft system; dampers,

ejectors and air fans being provided for cooperation with each other, as shown in Fig. 7. 5 The circulation is as follows: Dampers D-l I in pipe L-5, D-I2 in pipe L-, are open, dampers D--IIL in pipe L-S, D-i in pipe L-i are closed, `as is damper D`I3 in stack S-Z; dampers D- in pipe L9 and D-i) in s-tack S-i are open. With the dampers in this position, air from blower BnFl flows through pipes L-5, L--i through ejector E-Z into flue C-Z to flue P-ZZ through regenerators R-S, R-5, R-li and the interconnecting flues to oven heating flue I, the waste gases pass out through valve V-i into flue P-i, regenerators R-, R-2, R-3 and the interconnecting ilues to ue C-I The waste gas is drawn from the oven through ejector E-l by means of blower B-FZ, air enters pipes L--l, L-9, then around ejector E-I to stack S-i, thence to atmosphere The air swiftly passing around ejector E--i flows 4upward through stack S-I carrying the waste products to the atmosphere. The dampers are reversed by a conventional clock mechanism at fixed intervals and the circulation of air then passes to the oven through flue C-l, regenerators R-L R2, Pif-3, and the interconnecting fiues to heating nue 5. The Waste gas passing downward through regenerators R-i, R-E, R-S and the interconnecting ilues to ejector E-2 to atmos- .phere via stack S-Z.

The improved method embodying the present invention can be carried into practice in any oon' vem'entmanner, but it is preferred to conduct the operations of the novel method in the cracking and `coking oven described hereinabove.

The following is a brief description of the operation of this invention when heat treating 8.5 degree A. P. I. Dubbs cracked residuum oil for the production of electrode coke from the carbon content of the heavy oil While heat treating the oil vapors for the recovery of aromatic oils, such as benzol, toluol, and Xylol.

The heavy oil or oil tar is preferably first preheated to about '700 F. At this temperature the oil is continuously sprayed into the coking cham- Vber and immediately covers the entire or substantially the entire hot oven oor or the carbonized residue thereon. The gasifying of the hot oil starts immediately (i. e. volatilizing hydrocarbon vapors, etc.), as well as the coking process (i. e; carbonizing the residue, etc.). An eight hour operating cycle divided as follows is preferred. v(The oven is said to be on stream whenV oil is being continuously charged into the oven). Oven on stream, continuously about five and one-half hours, coking time required including the time on stream, about seven hours, cal- 50 oining the coked or carbonized residue about thirty minutes, pushing coke from the oven and luting or sealing the oven doors and burning carbon, thirty minutes, thus completing the eight hour cycle. In practice operating three eight hour cycles each twenty-four hours can be effected.

'The control of oven floor temperature is necessary in order not to produce cracking of the oil vapors when oil, tar, or the like is continuously sprayed over the floor surface. After the calcining of the coke in the oven before pushing the coke, the entire oor area is overheated due to the combustion of so-me of the coke. The pro cedure preferably used ,is as follows: All gas to the burners in the heating lues under the oven floor is'shut off and the floor temperature is reduced from an average temperature of about 2000 F. to about 1350 F. This quick drop in temperature is induced by the cold air forced into the oven through ports I-I-3, while scurng the small amountof surface floor carbon.

As the oil covers the iioor, the gas is then turned on and the burners in the heating flues ignited from the stored heat in the brick walls. As the coke increases in depth over the floor surface, more gas is used at the burners to raise the temperature as required for coking the incoming Y oil on stream which is being deposited over the ever increasing depth of coke until at the end oi' the oil input, when the coke bed is about 7 inches thick on an average, then the temperature in the heating flues is raised to an average temperature of about 2750 F., which is necessary to complete the coking of the oil carbon residue on the top surface of the coke.

The foregoing description covers the distillation of the oil in the broad oven, whereas the next one relating to an important feature of this invention concerns the production of aromatic hydrocarbons from straight chain hydrocarbons evolved in the oven. It has been found that the exothermic reaction temperature relating to the f conversion of straight chain hydrocarbons to aromatic hydrocarbons will average about 1350 F., and also that Contact of the oil vapors with hot surfaces of the cracking and heat treating chamber is required to bring about the reaction in the oil vapors, to wit: the conversion of straight'chain hydrocarbons to aromatic hydrocarbons. To insure the contact of the hot hy`- drocarbon vapors with hot cracking and heat treating surfaces, meansfor providing turbulence of the Yhot vapors has been provided. I have found that radiated heat of a temperature higher than 1350 F. will not release the aromatic light oils from the oil vapors. In other words, I have discovered that it is necessary to cause the hydrocarbon vapors to contact the hot surfaces in order to effect -the conversion of hydrocarbons and the formation of aro-matics from straightl bulence and surface contact as required for theA production or aromatic oils.

The present invention provides a novel cracking and coking oven which in actual practice is preferably about forty feet long inside oven doors K-l, about nine feet in width throughout from the pusher-end door to the discharge-end doo-r, and about two and one half feet in height or depth. Associated with the roof of the oven is a cracking chamber constituted of a plurality of ues, preferably eight, each of which has a free cross-sectional area of about one hundred square inches. Although the cracking lchamber H-d is heated in part from th-e heat coming from oven H-|, the independent heating iiues 6 provide additional heat required for cracking and heat treating the hydrocarbon vapors. Each separate heating iue preferably has a cross-sectional area of about sixty to about one hundred square inches depending upon the volume of oil vapor and has a control for the a-mount of fuel to be burned and thus the amount of heat evolved and the temperature attained. tis preferred vto control the heat and to maintain a wall temperature of about 1800 E. in the cracking chamber 1.'0 for the conversion of straight chain hydrocarbons to aromatics, such as benZol, toluol vand Xylol. For the purpose of evolving hydrocarbon vapors from oil residues, tar and the like in the oven, a

. controlled amount of heat is supplied. by the heating flue system which preferably has an odd number of nues in series, such, for example, as ve 'as shown in the drawing. 'Ihe velocity of flow in the fiues is preferably about thirty to about thirty-five feet per second. When a rich fuel, such as oil or coke oven gas, is burned in the heating system, each fiue has a cross-section of about one hundred square inches; whereas when a lean gas is used, each flue has a crosssection of about one hundred and thirty square inches. Each set of regenerators (Rf-I, Rf-2 and R--S or R-IS, R- and lit-6) has a vvolume of about 600 cubic feet and is capable of handling about 800 cubic feet of outgoing hot waste gas or incoming air per minute vwhich means that the temperature Aof vthe Waste gas is preferably reduced from about 2750 F. to about 550 F. and the air is preheated from about 70 F. to about 1700 F. As is custo-mary, the valves of the Isley system have to be reversed from time to time and, as a general rule, the interval of reversal is preferably about 15 minutes. With the aforesaid arrangement, about 130 cubic feet of gas per minute (75,000 B. t. u.s) or one half of one gallon of oil (75,000 B. t. u.s) are burned in the main heating flues under the oven whereas about 50 cubic feet of gas (28,500 B. t. u.s) are burned in the auxiliary heating flues whereby electrode coke, gas, aromatics and other by-products are produced in the novel cracking and coking oven.

It is to be observed that the present invention contemplates not only asingle oven but a plurality of such ovens. Due to the unique combination of structural elements in the present cracking and coking oven, it is possible to construct and operate a single oven or two, three, four, five or more ovens in contradistinction to the large slot ovens which require the building of large numbers of ovens in order to make the structure practical, economical and commercial. When a plurality of ovens similar to the one illustrated in Fig. 1 are yto be constructed then the steel work and buck stays are removed to the end of the battery of ovens and the pipes suppiying air and fuel are incorporated directly in the brick work. Of course, the conventional auxiliaries are employed. As these are well known and understood by those skilled in the art, the conventional auxiliaries have not been illustrated and described. Reference to any appropriate publication will give the illustration of the auxiliaries and a description. Thus, for instance, reference may `be had to the following textbooks:

Furthermore, the present inventionv provides a method of p'yrolytically treating hydrocarbons to cause a conversion thereof and the provision of a broad cracking and coking oven in which the aforesaid method can be carried into practica' including the cracking of straight chain hydrocarbons like parafns occurring in petroleum and the like, to lconvert them into aromatic hydrocarbons, such as benzol, toluol, xylol, naphthalene, anthracene, and the like, while evolving vapors containing straight chain hydrocarbons from a fluid hydrocarbon mass and canbonizing the residue thereof into coke. In the new cracking and coking oven the main heating flues are located under the sole or oor of the oven which provides the heat for evolving the vapors from the fluid hydrocarbon mass in the oven, for the coking of the residue of said mass, and for supplying a part of vthe heat for the cracking .cham- -ber superimposed above and associated with the roof of the oven, Whereas the auxiliary heat nues are provided directly under the cracking chamber for the purpose of controlling the heat treatment of the hydrocarbon vapors coming from the oven and passing through the channels or flues of the cracking chamber, whereby the hydrocarbons are converted, particularly the straight chain or parafiin hydrocarbons, into aromatic hydrocarbons.

The theory underlying the pyrolysis of hydrocarbons is not completely understood at the present time and the mechanism of the chemical reactions involved is very complex. In the conversion of hydrocarbons, a variety of reactions occurs including decomposition, polymerization,

and side reactions. The aforesaid reactions include those of the endothermic type as well as those of the exothermic type. Generally speaking, the decomposition of hydrocarbons belongs to the endothermic type, whereas those relating to polymerization belong to the exothermic type. In the conversion of straight chain hydrocarbons to aromatic hydrocarbons it appears that the first reactions are of the decomposition variety and are subsequently followed by those of a polymerizing variety which may also be accompanied with various side reactions. Although many factors are involved, it appears that the more important are temperature, time or space velocity, turbulence of the vapors, pressure, concentration, contacting surfaces and catalysts. Under certainconditions, such products as butadiene may be formed. By controlling the conditions in the cracking and heat treating chamber a variety of products can be produced. It is understood, however, that the present invention is not to be restricted to and dependent upon any theory including the foregoing.

Although the present invention has been disclosed in connection with a preferred embodiment thereof, variations and modications mayV be resorted to by those skilled in the art without departing from the true spirit and scope of the invention as disclosed in the foregoing specification and defined by the appended claims. Thus, for instance, the present method and coking and cracking oven can be used for coking and d istilling coal tar and coal tar pitches, for the recovery of a variety of compounds including .creosote and tar acids. The novel method may like- Wise be used for the treatment of peat for the recovery of volatile products including volatile oils. Moreover the novel process and oven can be used for heating of oil shales for the recovery of various icy-products including oil and fractions thereof.

I claim:

l, In a refractory cracking and coking oven of the broad rectangular sole-fired type having a sealable broad refractory coking oven of a long rectangular type being broader than it is high and adapted to receive carbonaceous material capable of evolving upon being heated volatile vapors including straight chain hydrocarbon vapors and a residue capable of being carbonized and coked, and a main heating system located under substantially the entire sole of said oven to eiect a substantially uniform heating of substantially the entire sole whereby vapors are evolved from carbonaceous material in said oven and some heat is supplied to said cracking chamber, for pyrolytically treating carbonaceous material including fluid hydrocarbon masses such as petroleum, heavy oil, oil residue, tar, and the like to evolve vapors containing straight chain hydrocarbons such as paraffin hydrocarbons and then cracking said straight chain hydrocarbons and converting them into aromatic hydrocarbons such as benzol, toluol and xylol while carbonizing the residue into good coke having acceptable qualities and properties, the improvement which comprises a refractory cracking chamber superimposed above and associated with said oven for cracking and heat treating said hydrocarbon vapors to effect pyrolysis therein and conversion of straight chain hydrocarbons into aromatic hydrocarbons, said cracking chamber being divided into a plurality of longitudinally extending Zones by means of partitions extending longitudinally thereof, each of said partitions having a multiplicity of projections for producing turbulence in said hydrocarbon vapors, means connecting said coking oven with said cracking chamber to conduct the volatile vapors including straight chain hydrocarbon vapors evolved in said coking oven to said cracking chamber, and an auxiliary heating system interposed between the top of said oven and the bottom of said cracking chamber for supplying the rest of the heat required in said chamber, said auxiliary heating system having independent control whereby the temperature in the cracking chamber may be independently controlled relative to that of the coking oven and desired aromatic temperatures may be maintained within said cracking chamber to effect the desired pyrolysis of vapors therein including the conversion of straight chain hydrocarbon vapors into aromatic hydrocarbon vapors.

2. In a refractory cracking and coking oven of the broad rectangular sole-fired type having a broad refractory coking oven of the long rectangular type being broader than it is high and adapted to receive carbonaceous material including fluid hydrocarbon masses such as petroleum, heavy oil, cil residues, tar and the like capable of evolving volatile vapors including straight chain hydrocarbons upon being heated, a door provided at each end of the oven for sealing the same against the admission of air, and a main heating system located underneath the sole of said oven for providing suicient heat to evolve said vapors from the said carbonaceous material and to coke the residue thereof and for providing substantially uniform heat throughout the sole of said oven without cracking straight chain hydrocarbons therein and without overcoking residue in one part and undercoking residue in another part of the oven, for pyrolyticaly treating carbonaceous material including nuid hydrocarbon masses such as petroleum, heavy oil, oil residue, tar, and the like to evolve vapors containing straight chain hydrocarbons such as parafiin hydrocarbons and then cracking said straight chain hydrocarbons and converting them into aromatic hydrocarbons such as benzol, toluol and xylol while carboniaing the residue intogood coke having acceptablequalities and properties, the improvement which comprises a refractory cracking chamber superimposed above and V associated with the roof of said coking oven, said cracking chamber beiner divided into a plurality of longitudinally extending zones by means of partitions extending longitudinally thereof, each of said partitions having a multiplicity of projections for producing turbulence in said hydrocarbon vapors, and said partitions being in heat conducting relationship with the heated bottom of the cracking chamber, whereby heat is transmitted to the cracking zones by the walls thereof as well as by the bottom thereof, a flue connecting said oven with said cracking chamber for conducting vapors from said oven toisaid chamber, and an auxiliary lheating system located underneath said cracking chamber and above the roof of said coking oven for supplying a desired and controlled amount of heat to establish predetermined thermal conditions Within said cracking chamber to cause the conversion of straight chain hydrocarbons to aromatic hydrocarbons including benzol, toluol, and xylol whereby the ternperature in theV cracking chamber may be independently controlled relativev to that of the coking oven.v

3. In a refractory cracking and coking oven of the broad rectangular sole-fired type having a scalable broad refractory coking oven of a long rectangular type being broader than it is high and adapted to receive carbonaceous material capable of evolving upon being heated volatile vapors including straight chain hydrocarbon vapors and a residue lcapable of f beingcarbonized and-coked, anda main heating system located under substantially the entire sole of said oven to effect a substantially uniform heatingof substantially the entire sole whereby vapors are evolved from carbonaceous material in said oven and some heat is supplied to said'cracking chamber, for pyrolytically treating carbonaceous material including fluid hydrocarbon masses ysuch as petroleum, heavy oil, oil residue, tar, and the like to evolve vapors containing straight chain hydrocarbons such as parain hydrocarbons and then' cracking said straight chain hydrocarbons and converting them into yaromatic hydrocarbons such as benzol, toluol and xylol While carbcnizing the residue into good coke having acceptable qualities and propertiesthe improvement which comprises a refractory cracking chamber superimposed above and associated with said oven for cracking and heat treating said `hydrocarbon vapors to eilect pyrolysis therein and conversio-n of straight chain hydrocarbons into aromatic hydrocarbons, said cracldng chamber being divided into a plurality f` longitudinally extending Zones by means ci partitions extending longitudinally thereof, eachof said partitions having a multiplicity of projections for producing turbulence in said hydrocarbon vapors, means connecting said coking oven with said cracking chamber to conduct the volatile vapors including straight chain hydrocarbon vapors evolved-in said'coking oven to said cracking chamber, and an auxiliary heating system interposed between the top of said oven and the bottom of said cracking chamber for supplying the rest of the heat required said chamber, said auxiliaryheating system having independent control whereby the temperatherein including the conversion of straight chain hydrocarbon vapors into aromatic hydrocarbon vapors, and independent burners disposed in the flues' or the auxiliary heating system whereby the temperature' in the cracking chamber may be independently controlled relative to that of the coke oven.

4. In a refractory cracking and coking oven of the broad rectangular sole-fired type having a scalable broad refractory cokingoven of a long rectangular type being broader than it is high and adapted to receive carbonaceous material capable of evolving upon being heated volatile vapors including straight chain hydrocarbon vapors and a residue capable of being carbonized and coked, and a main heating system located Arudder substantially the entire sole of said oven to effect a substantially uniform heating of substantially the entire sole whereby vapors are evolved from carbonaceous material in said oven and some heat is supplied to said cracking chamber forpyrolytically treating carbonaceous matcrial including kfluid hydrocarbon masses such as petroleum, heavy oil, oil residue, tar, and the like t0 evolve vapors containing straight chainy hydrocarbons such as parafn hydrocarbons and then cracking said straight chain hydrocarbons and converting them into aromatic hydrocarbons such as benzol, toluol and Xylol while carbonizing the residue into good coke having acceptable qualities and properties, the improvement which comprises a refractory cracking chamber superimposed above and associated with said oven for cracking and heat treating said hydrocarbon vapors to effect pyrolysis therein and conversion of straight chain hydrocarbons into aromatic hydrocarbons, said cracking chamber being vided into a plurality of vapor cracking and heat treating flues by meansvof partitions capable of producing turbulence in said hydrocarbon vapors, means` connecting said coking oven with said cracking chamber to conduct the volatile vapors including straight chain hydrocarbon vapors evolved` in said coking oven to said cracking chamber, and an auxiliary heating system interposed between thetop of 'said oven and the bottom of said cracking chamber forA supplying the' rest of the .heat'required in said chamber,v said auxiliary `heating, system having independent control whereby the temperature in the cracking chamber may be independently controlled rela-1; tive to that of Vthe coking oven and desired aromatic cracking temperatures may7 be maintained' within said cracking chamber to effect the desired' pyrolysis of vapors therein including the conversion of straight chain hydrocarbon vapors into aromatic hydrocarbon vapors.

5. In a refractory cracking and coking oven of the-broad rectangular sole-red type having a broad refractory coking oven of the long rectangular type being broader than, it is high and adapted to receive carbonacecus material including iiuid hydrocarbon masses such as petroleum,

heavy oil, oil residues, tar andthe'like capable of evolving volatile vapors including' straight chain'hydrocarbons upon being heated, a door provided at each endof the oven forsealing the same against the admission of air. and amain heating system located underneath the sole of saidbven for providing sufcient heat tov evolve said vapors from the said carbonaceous material and to coke the residue thereof and for providing substantially uniform heat throughout the sole of said oven without cracking straight chain hydrocarbons therein and Without overcoking residue in one part and undercoking residue in another part oi the oven and for pyrolytically treating carbonaceous material including fluid hydrocarbon masses such as petroleum, heavy oil, oil residue, tar, and the liketo evolve vapors containing straight chain hydrocarbons such as parafn hydrocarbons and then cracking said straight chain hydrocarbons and converting them into aromatic hydrocarbons such as benzol, toluol and Xylol while carbonizing the residue into good coke having acceptable qualities and properties, the improvement which -comprises a refractory cracking chamber superimposed above and associated with the roof of said coking oven, means connecting said coking oven with said cracking chamber for conducting vapors from said oven to said chamber, said cracking chamber containing at least one vapor cracking and heat treating iiue made by means of partitions in heat conducting relationship with the heated bottom of the cracking chamber whereby heat is transmitted to the cracking iue by the walls thereof as Well as by the bottom thereof, and an auxiliary heating system located underneath said cracking chamber and above the roof of said coking -oven for supplying a desired and controlled amount of heat to establish predetermined thermal conditions within said cracking chamber to cause the conversion of straight chain hydrocarbons to aromatic hydrocarbons including benZol, toluol, and xylol whereby the temperature in the cracking chamber may be independently controlled relative to that of the coking oven.

6. n a refractorycracking and coking oven of the broad rectangular sole-iired type having a scalable broad refractory coking oven of a long rectangular type being broader than it is high and adapted to receive carbonaceous material capable of evolving upon being heated volatile vapors including straight chainv hydrocarbon vapors and a residue capable of being carbonized and coked, and a main heating system located under the sole of said oven for providing suficient heat to evolve said vapors-from said carbonaceous material in said oven and to coke the residue thereof and for providing substantially uniform heat throughout the sole of said oven without crackingand without overcoking residue in one part and undercoking residue in another part of the oven and for pyrolytically treating carbonaceous material including fluid hydrocarbon masses such as petroleum, heavy cil, oil residue, tar, and the like to evolve vapors containing straight chain hydrocarbons therein such as paraiiin hydrocarbons and then cracking said straight chain hydrocarbons and converting them into aromatic hydrocarbons such as benZol, toluol and Xylol while carbonizing theresidue into good coke having acceptable qualities and properties, a chimneysystem for conductinghot waste products of combustion from said/main heating system to the atmospheregand a heat exchange system interposed between said main heating system and said chimney system for exchanging heat from the hot waste products of combustion coming from said heating system to preheat incoming air -and/or gas going to said heating system, the improvement which comprises a refractory cracking chamber superim..

straight chain hydrocarbons into aromatic hydrocarbons, said cracking chamber being divided into a plurality o vapor cracking and heat treating lues by means of partitions capable of producing turbulence in said hydrocarbon vapors, means connecting said ccking oven with said cracking chamber to conduct the volatile vapors including straight chain hydrocarbon vapors evolved in said coking oven to said cracking chamber, an auxiliary heating system interposed between the top of said oven and the bottom of f said cracking chamber for supplying the rest of the heat required in said chamber, said auxiliary heating system having independent control whereby the temperature in the cracking chamber may be independently controlled relative to that of the coking oven and desired aromatic cracking temperatures may be maintained within said cracking chamber to eiect the desired DY- rolysis of vapors therein including the conversion of straight chain hydrocarbon vapors into aromatic hydrocarbon vapors, and independent burners disposed in the nues of lthe auxiliary heating system whereby the temperature in the cracking chamber may be independently controlled relative to that of the coke oven.

7. In a refractory cracking and coking oven of the broad rectangular sole-red type having a sealabie broad. refractory coking oven of a loner rectangular type being broader than it is high and adapted to receive carbonaceous material capable of evolving upon being heated volatile vapors including straight chain hydrocarbon vapors and a residue capable of being carbonized and ccked, and a main heating system located under the soie of said oven for providing sufficient heat to evolve said vapors from said carbolnaceous material in said o-ven and to coke the residue thereof and i'or providing substantially uni-form heat throughout the sole ofA said oven without cracking and without overcoking residue in one part and undercoking residue in another part of the oven and for pyrolytically treating carbonaceous material including fluid hydrocarbon masses such as petroleum, heavy oil, oil residue, tar, and the like to evolve vapors containing straight chain hydrocarbons therein such as parain hydrocarbons and then cracking said straight chain hydrocarbons and converting them into aromatic hydrocarbons such as benzol, toluol and Xylol while carbonizing the residue into good coke having acceptable qualities and properties, a chimney system for conducting hot waste products of combustion from said main heating system to the atmosphere, and a heat regenerative system interposed between said main heating system and said chimney system for exchanging heat from the hot waste products of combustion coming from said heating system to preheat incoming air and/or gas going to said heating system, the improvement which comprises a refractory cracking chamber superimposed above and associated with said oven for cracking and heat treating said hydrocarbon vapors to effect pyroylsis therein and conversion of straight chain hydrocarbons into aromatic hydrocarbons, said cracking chamber being divided into a plurality of vapor cracking and heat treating ues by means of partitions' capable of producing turbulence in said hydrocarbon vapors and extending substantially from one end of said oven to substantially the other end, means connecting said 17 coking oven With said cracking chamber to conduct the volatile vapors including straight chain hydrocarbon vapors evolved in said coking oven to said cracking chamber, an auxiliaryrheating system interposed between the top of said oven and the bottom of said cracking chamber for supplying the rest of the heat required in said chamber, said auxiliary heating system comprising a plurality of ues extending underneath substantially the entire cracking chamber and having independent control whereby the temperature in the cracking chamber may be independently controlled relative to that of the coking oven 18 and desired aromatic cracking temperatures may be maintained Within said cracking chamber to eiect the desired pyrclysis of vapors therein including the conversion of straight chain hydrocarbon vapors into aromatic hydrocarbon vapors, a multiplicity of projections in said flues for producing turbulence in said hydrocarbon vapors, and independent burners disposed in the flues of the auxiliary heating system whereby the temperature in the cracking chamber may be independently controlled relative to that of the coke oven.

CHARLES H. HUGHES.

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