US1844889A - Distillation of tar, etc. - Google Patents

Description

Feb. 9,1932. s. P. MILLER- 1,8 ,889

DISTILLATION TAR,' ETC Filed Dec. 31, 1926 5 h ts-Sheet 1 2/ j x /5 6 n 4 22 i-i f-f "F /6 II 7 INVENTOR ATTORNEYS Feb. 9, 1932. s. P. MILLER DISTILLATION OF TAR,

ETC

Filed Dec. 31-, 1926 5 Sheets-Sheet 2 (Luau-m ATTORNEYS Feb. 9, 1932. s. P. MILLER DISTILLATION OF TAR, ETC

Filed Dec. 5 Sheets-Sheet 3 INVENTOR ATTORNEYS Feb. 9, 1932. s. P. MILLER DISTILLATION OF TAR,

ETC

Filed Dec. 31, 1926 5 Sheets-Sheet INVENTOR PM %W MW- W ATTORNEYS Feb. 9, 1932. s. P MILLER DISTILLATION OF TAR, ETC

Filed Dec. 31, 1926 5 Sheets-Sheet 5 Ffg R INVENTOR ATTORNEYS Patented Feb. 9, 1932 UNITED STATES PATENT OFFICE STUART PARMELEE MILLER, OF TENAFLY, NEW JERSEY, ASSIGNOB TO THE BARRETT COMPANY, OF NEW YORK, N. Y., CORPORATION OF NEW JERSEY DISTILLATION OF TAR, ETC.

Application filed December 31, 1926. Serial No. 158,137.

his invention relates to an improved method of tar distillation and the productionof pitch and distillate oils therefrom. More particularly, the invention relateswto improvements in the distillation of coal tar and the production of pitches anddist llates at coal distillation plants, suchas byproduct coke ovens.

In the ordinary operation of by-product coke ovens the gases produced by the coking operation pass from the individual ovens through individual uptake pipes and goosenecks to a collector main or mains common to a battery of ovens. The coke oven gases leaving the ovens at a high temperature are cooled to separate tar constituents therefrom, the tar constituents being separated partly in the collector mains and partly in subsequent condensers.

Coal tar produced at by-product coke ovens is commonly shipped or conveyed to tar distillation plants where. it is subjected to distillation for the recovery of coal tar distillates and the production of pitches as residues of the distillation.

The present invention provides an improved process of tar distillation in which the tar is distilled directly at the by-product coke oven plants without the need of a separate tar distillation plant and vithout transportation expense, and with the pro duction from the tar of distilled oils and of pitches as residue of the distillation.

According to the present invention, the hot coke oven gases, as they come from one or more of the individual coke ovens, are utilized for the distillation of tar and the separation of vaporizable oils therefrom which are separately recovered, and the production of pitches, by bringing the tar into intimate contact with the hot coke oven gases immediately after they leave such coke ovens, or at least while they are at a temperature high enough to accomplish the desired distillation.

In the improved process of the present invention, the distillation of the tar is carried out with separate condensation and recovery of the distilled oils, admixed with so only such oil and tar constituents as are contained in or remain in the coke oven gas employed for the distillation.

According to the present invention, the tar to be distilled is sprayed or otherwise brought directly into contact with the hot coke oven gases from a limited number of individual ovens, at a sufficiently high temperature so that the tar is effectively distilled thereby, with separation theretrom of a greater or less amount of volatile oils, leaving a heavier tar or pitch as the residuum product of the distillation, and the gases and admixed vapors from the distillation are kept separate from the coke oven gases from the other ovens. The spraying of the. tar into the hot coke oven gases results in partial cooling of these gases and separation therefrom of more or less of the heavier tar constitucuts, a proportion of which are .thus thrown down and added to the pitch residue from the tar distillation. This distillation of the tar also results in an increase of condensable vapors in the hot coke oven gases treated as well as in the partial or preliminary removal from the gases of heavier tar constituents, so that these coke oven gases in their partially purified condition and with the increased amount of vapors from the distillation of the tar, difier in composition from the ordinary coke oven gases not so treated.

In, the practice of the invention, the tar to be distilled is sprayed or atomized into the hot coke oven gases, or is otherwise brought directly into intimate contact therewith, so that the hot gases can heat and distill the tar and carry off the distillate vapors, and these vapors are then separately condensed, to-

gether with vapors which the gases themselves contain.

Certain of the individual coke ovens, according to the present invention, are provided with a gas collecting system or systems of a construction which will enable the tar to be sprayed or otherwise introduced directly into a stream of the hot coke oven gas immediately after it leaves the coke oven, or before the temperature has been greatly reduced.

Such gas collecting system or systems may advantageously be uptake stills in the form of modified uptake pipes, such as hereinafter ordinary manner.

described, in which the tar is sprayed or atomized into the stream of the hot coke oven gas while the gas is at substantially its maximum temperature, but the invention in its broader aspects is not limited to the use of such uptake stills. Other apparatus may be employed to utilize .the hot gases for the direct distillation of tar.

The distilling capacity of the gases from a single coke oven is greatly in excess of that required for distillation of the'amount of tar which a single coke oven produces, so that the tar from a considerable number of coke ovens can be distilled in a single uptake pipe by the hot gases from a single oven.

In the construction of a battery of ovens, for distilling all the tar produced on the battery, it is therefore sufficient to provide a few only of the individual ovens with uptake pi e stills for distilling tar with the hot co e oven gases, ancLthe remainder of the coke ovens of the battery may be operated in the ordinary way, the recovery of coal tar from their gases being accomplished in the Such recovered coal tar may then be distilled in the few uptake pipe stills to produce pitches therefrom and to permit recovery of the vaporized oils from the distilled tar, together with tar and oils normally present in the gases.

F or the most part, the construction of the coke oven battery and of'its by-product recovery system may remain unchanged, so that the greater proportion of the coke ovens may be or remain of usual construction, and the gases therefrom maybe collected in the usual collector main, and the tar separated therefrom in the usual way.

A part only-of the coke oven battery will be changed by the provision of the uptake stills arranged for the distillation of tar by the hot coke oven gases and for the production of distillate and pitch therefrom. This part of the battery, provided with such modied construction of the gas outlet pipes, has itsown collecting, cooling and condensing system so that the coke oven gases employed for and mixed with the vapors produced from the distillation of the tar, can be cooled for the separation of tar and oil constituents therefrom independently of the main gas collecting, cooling and recovery system of the battery.

It is one advantage of the present invention that it can bedirectly applied to existing or present day coke oven construction. Present day coke" oven operation so far as the production of coke is concerned, is unaffected, while nevertheless tar may be distilled and pitch produced and oils recovered in the separate gas collecting and condensing system. This special distilling and condensing system does not interfere with the operation of the coke ovens. The by-product re covery system for the coke ovens which are not modified by the provision of the uptake pipe still can be operated in the ordinary way.

Another important advantage of the present invention is that the employment of a separate collector main, with separate cooling and condensing system insures an easier control of the temperature of the distillation process than would be possible with the use of the uptake pipe stills leading to a collector main in common with that for the other ovens of the battery. In other words, the volume of tar required to produce a relatively large change in the temperature of the gases in the separate collector main and in the separate uptake stills would have relatively little eiiect upon the temperature of the total volume of gases evolved by the whole battery. Proper temperature control is important, when tar is introduced into the gases, because injury of the apparatus is avoided thereby and in addition products producible at definite temperature ranges may be secured with certainty.

The tar which is distilled according to the present invention may be tar produced at the same coke oven plant at which it is distilled, or it may be tar from another coke oven or other plant. The tar may be a heavy tar, light tar, or heavy or light tar constituents which it is desired to distill to separate distillate oils therefrom. Other tar, such as gas house tar, vertical retort tar or water gas tar, etc., can also be distilled. \Vhere blended or composite pitches are desired, or composite or blended distillates, two or more dif ferent kinds of tar may be separately distilled at the coke oven plant, or may be admixed in suitable proportions and be distilled together, giving directly a composite pitch product. \Vhere diil'erent tars are distilled, the resulting pitches may be-blended to give a composite product, and the distillates may likewise be blended when desired. For example, horizontal gas retort tar with high free carbon content can be admixed with coke oven tar and the mixture distilled to give a composite pitch higher in free carbon than the pitch from the coke oven tar and to give a composite oil distillate. The tar distilled may contain all or practically all of the condensible oils, in case all the tar constituents are normally condensed or collected together, or it may be a heavy tar containing only part of the oils. \Vhere mixed tars are distilled, the condensates condensed in the separate condensing system or systems will be of a composite character. \Vhere difi'erent tars are separately distilled, the gases and vapors from such separate distillation can be separately condensed in separate condensing systems, or condensed together in the same condensing system.

The amount of condensible oil vapors distilled from the tar in the present process may be in some cases less than the condensible oil vapor content of the coke oven gases employed for the distillation, particularly where the amount of tar distilled is regu- I tained in the coke oven gases, so that these gases may be doubled or more than doubled in their vapor content, giving a higher concentration of condensible vapors in the gases. Moreover, the effect of the distillation is proportionately to increase the content of relatively lighter oil vapors and to decrease proportionately' the content of heavy pitch constituents, owing to the purifying efiect of the tar spray in separating and throwing down some of the heavier constituents of the gases.

Where a few only of the coke ovens of a battery are employed for the distillation of tar and separate collection of oil, in accordance with the present invention, the separate condensing system or systems for the vapors from the coal gases of such ovens can be much smaller than the main condensing system for the remainder of the battery. Such separate condensing system or systems may be of similar. construction and operation as the ordinary condensing system, from the standpoint of oil recovery, or of different construction and operation. Owing to the increased condensible oil vapor content of the gases, a proportionately smaller amount of gases require handling, while, from corresponding quantities of the gases, a muchgreater amount of condensible constituents can be recovered than from ordinary coke oven gases.

Tar as commonly produced and collected at coke oven plants contains more or less water or ammonia liquor admixed therewith. Such tar can be employed directly and dehydrated as Well as distilled, or it can be partially or completely dehydrated before subjecting it to distillation according to the present invention. The tar may also be employed in a preheated and thinly fluid state for spraying into the hot coke oven gases.

The manner in which the tar is brought into direct contact with the hot vapors can be varied. A'suitable atomizing or spray nozzle, to which the preheated and thinly fluid tar is supplied under a sufiicient. pressure to bring about atomizing or spraying.

and resulting intimate contact of the tar with the hot gases, can be located in the upper part of the modified uptake pipe to-bring the tar into intimate contact with the hot gases.

A single tar spray can be used in each of the individual uptake pipes, or a plurality or series of such sprays, and the rate at which the tar is sprayed, as well as its temperature, can be regulated and controlled to obtain a greater or less degree of'distillation of the tar and the production of distillates of desired characteristics, and of harder or softer pitches or pitch-like products The gases esca ing from the top of a coke oven are at a. hig temperature, e. g., around 600 to 7 00 C., or in some cases much higher. The temperature of these gases is sufiiciently high so that effective distillation'of the tar can be accomplished by an intimate and regulated spray of the tar into the hot gases. By employing the gases at practically top-ofoven temperature their maximum heating and distilling effect is utilized. The amount of tar and the intimacy and time of contact of the particles of the tar spray with the gases, and the nature andamount of oil distilled therefrom, can be varied. Effective distillation can be accomplished with a temperature drop of the gases'while passing through the tar spray, of, for example, (3., although with increased amount of tar or increased intimacy and time of contact a greater drop in temperature and increased distillation of oil can be obtained.

The'tar in turn will be heated by the hot gases and its temperature may be Very con siderably raised. Part of the heat of the gases, however, is employed in vaporizing liquid constituents of the tar without corresponding increase in temperature of the tar, so that the maximum temperature of the tar and of the resulting pitch may be considerably below that of the gases.

In the carrying out of the process, the tar may be brought into contact with'the hot gases once only or it may be recirculated and again brought into contact with the hot coke ovengases to bring about further distillation and the production of harder pitches, or even pitches of modified character, such as pitches of increased carbon content. This further distillation may take place by recirculating the tar or pitch through the same distillation system, or through another or other hystems, so that distillates and pitch of the same or similar character are produced in theldifi'erent systems, or distillates and pitches bf dif' ferent character in the different systems. By regulation of the rate and type tar spray and its temperature of preheating, and by redistillation when necessary, it is possible to regulate the hardness of the pitches produced, and produce softer or harder pitches, as desired, and oils of diflerent characteristics mav be formed. The further distillation of the pitch first produced to recover additional oil therefrom, can be carried out in the same uptake pipe still, or it may be subjected to further distillation in another uptake pipe still. By operating separate uptake pipe stills as separate systems, it is possible to produce distillates and pitch of different characteristics simultaneously, While by operating separate condensing systems with such separate distillation systems,

condensed products of area-m properties can be simultaneously produced.

In a coke oven plant having a small. battery of ovens, for example, a twenty oven battery, one or two uptake stills may be sufficient to distill the tar from the remaining ovens of the battery and such still or stills may have a separate condensing system. In a larger coke oven plant having a large number of ovens in the same or separate batteries, a larger number of the uptakestills will be required to distill the tar produced by the remaining ovens of the battery or batteries. If tar from an outside source is distilled, a larger number of uptake stills may similarly be rerprireal. lVhere a coke oven plant has several batteries of ovens, one or more uptake stills may be provided on each battery, or a suflicient number may be provided on a single battery to distill the tar produced by the other batteries and by the other ovens of the same battery, to yield the desired quantities and qualities of distillates or of pitches.

\Vhere several uptake pipe stills are provided for the distillation of a large amount of tar, all of the uptake stills may be connected to the same condensing system, or two or more separate condensing systems may be provicr-d. "Frhere two or more or" the uptake stills are combined with .e same condensing stem, these uptake 8H s may advantagea separate co ctoi niain tor cole gases if: stills so may pass separate syste uptake ovided, 1,

r "'S COLA,

, cone sirable to .1Sll3l6 const system beyond ti tins or the 'ns is as: n' amount into t mains, or by sprayi. anthracene oil, etc., i

temperature so that the gases are not cooled to such an extent that too large an amount of the condensible constituents areseparat-ed in the collector main. Tar which .is thus sprayed into the collector main may be dehydrated and recovered from the main along with condensed constituents from the gases as a dehydrated and partially distilled tar product. The gases, even after passin through the vuptake stills will be at a su ficiently high temperature to effect distillation of tar brought into contact therewith, as'by spraying it intimately into the gases in the separate collector main. In such case, the hot coke oven gases will be employed in a two-stage distillation, first in the uptake still and second in the collector main. The tar which is dehydrated, or preheated, or both, in the collector main, may then be returned to one of the uptake stills to effect its furher distillation and to produce pitch thererom.

The gases after passing through the separate collector main then pass to the condensing system in which further condensation of condensible constituents takes place. Such condensation may be a fractional condensation in direct or indirect coolers or condensers of the type now commonly employed for recovering condensible constituents from coke oven gases, or the gases may be subjected to fractional condensation in a stage-by-stage scrubbing system, as for example, by scrubhing them with oils progressively lower temperatures.

The present invention includes not only the cteristics described.

' "uccc incre; us possiole ulating the snray .Qti kept in conta ,1; it time to raise ""ion temeater and to pitches produced from the tar produced at horizontal gas retort plants. Such high carbon pitches are in the nature of synthetic gas house tar pitches.

In addition to producing pitches of different properties and characteristics, the present invention enables distillates to be obtained from tars or tar fractions or oils, particularly where it is desired to redistill a dirty oil, or an oil contaminated with tar or pitch,

to produce a cleaner distillate oil therefrom and a pitch residue. Such distillation of oils can, moreover, be carried out simultaneously with the distillation of tar by operating one or more of the uptake stills as tar stills to produce -pitclr-anddistill'ates, and by operating one or more of the uptake stills for the distillation of oils to separate them into various constituents. In systems where different uptake pipe stills, or diflerent groups of uptake pipe stills, are connected to separate condensing systems, each system may if desired, operate upon a different material; for example, one system may distill tar in the manner described, and another system may distill a mixture of oils for the separation of difierent oil constituents therefrom.

It is one advantage of the improved.system of the present invention that it makes possible the keeping of the distilled oils separate from the main condensing system of the coke oven battery, so that, whatever oils or tar constituents are distilled in the uptake stills, they can be separately recovered; while by operating different distillation and condensing systems. different products can be simultaneouslv distilled. A mixture of oils having a wide boiling point range can be subjected to distillation in one of the uptake stills, or in a group of uptake stills, having a separa e condensing system, and the mixture thereby fractionated, giving the heaviest fraction as products from the uptake stills, admixed with such tar constituents as are separated from the coke oven gases in the uptake still, while the other oil constituents can be recovered partly in the separate collector main or mains. and partly in the subsequent fractional condensers or coolers.

The present invention is thus of more or less general application to the distillation of tar and oils and the recovery of distillates. It involves utilization of the hot coke oven gases for the distillation of the tar or oil by bringing the tar or oil into direct contact therewith and separate condensation of the resulting distillate or distillates fractionally or otherwise. The invention also includes an improved operation. of coke oven batteries or of coke oven plants in which the battery or battcrics are balanced in operation in the sense that part of the coke ovens are employed by providing them with uptake stills for the distillation of tar produced by the remainder of the battery or batteries, in such cases as it The invention will be further illustrated by the following more detailed description taken together with the accompanying drawings, which show apparatus adapted for the practice of the process of the invention, but it is intended and will be understood that the invention is illustrated thereby but not limited thereto.

In the accompanying drawings,

Fig. 1 is a view in elevation with part in section showing a portion of a coke oven provided with an uptake pipe still and separate collector main,

Fig. 2 shows a plan .view of a part of a battery of coke ovens with part-of the ovens provided with the uptake pipe'stills and with a separate condensing system,

Fig. 3 is an elevation taken at right angles The invention is of more or less general application to different types and constructions of by-product coke ovens such as Semet- Solvay ovens, Koppers ovens, etc., but will be more particularly described and illustrated in connection with by-product cok'e ovens of the Semet-Solvay type.

In Fig. 1 is illustrated one of the coke ovens of a battery, with gas piping modified to provide for the distillation of tar or oils with the hot coke oven gases which rise from;

the oven. The coke oven is illustrated conventionally at 1 and has the usualgas outlet 2 for the escape of the hot coke oven gases. The uptake'pipe still, viz, the modified uptake pipe, may consist generally of the outlet pipe 3, the casing 4 and the uptake L 5. The outlet pipe 3 is seated in a suitable seal over the gas outlet 2 and connects at its upper end with the lower end of the casing 4. The upper end of the casing 4 connects with the uptake L 5 which leads to a main 6 which may be similar to the ordinary collector main but smaller in size. The casing 4 is enlarged to provide a space around the inner pipe 7 which extends upwardly into the said enlarged casing. The lower ends of the pipe 7 and the casing 4 are preferably integral or threaded one within the other or joined by means of a pipe stills in a different manner from thatin which the others are-operated. For example, tar which has been distilled in one uptake pipe can be redistilled in another uptake pipe still to drive off an additional amount of heavier oil vapors therefrom and give a heavier pitch. In such cases, separate collecting and condensing systems can be provided for the individual uptake pipe stills so that heavier oils can be recovered from one than from another. Thus, for example, uptake pipe stills 5?) may be connected to two of the ovens and to a small collector main 6?). Tar or oil to be distilled may be fed to the stills through spray nozzles 96 and the distillation may be conducted as in-the stills 5. The pitch produced in the stills will be withdrawn through a pipe 11?) and the gases carrying the distilled vapors will be withdrawn through a cross-over main b and delivered to condensers 31b and 32b to which decanters 34b are connected. A decanter 337) permits separation of the condensed oils from the ammonia liquor which separates in the crossover main. The condenser 326 may be connected to the exhauster 35 to facilitate the flow of gases and vapors through the system.

In Fig. 4 an arrangement is shown for recirculating the pitch produced from one distillation so that it may be redistilled in a second distillation, and the coke oven gases employed in said respective distillation, with difierent oil vapor content, can be separately collected and condensed in separate condensing systems. In this way, a fractional dis-' tillation of the tar can be effected, taking off first the more volatile constituents and giving a soft pitch, then redistilling the soft pitch to take off heavier constituents and give a harder pitch, and the lighter and heavier oils driven off by these successive distillations can be separately condensed along with the vapors of the coke oven gases by which they are carried. In Fig. 4 the pitch receptacle 19 is shown as having a pipe 27 leading therefrom to the spray nozzle and a pump 26.

in this line for recirculation of the pitch or tar.

Onesuitable form of spray nozzle is indicated in Fig. 8, this having an outer casing 36 with an inner core 31' having helical passages formed between it and the outer casing 36 and with the nozzle orifice 38. The construction is such that the tar or oil is discharged with a whirling motionin the form of a conical spray. The tar or oil, when it is preheated and thinly fluid, may be pumped to the nozzle under a suitable pressure, for example, 40 pounds per square inch and discharged through the nozzle so as to atomize or spray it into the hot uprising gas.

In the operation of the apparatus illustrated, and the carrying out of the process of the invention therein, the hot gases from the distillation of coal in the coke ovens pass upwardly throu h the uptake pipe stills and thence throng the connecting piping to the condensing system which in the apparatus illustrated is a small collector main. The remainder of the battery of ovens can be operated in the ordinary way to separatetar fractionally or completely from the' coke oven gases, as by spraying ammonia liquor or tar or both into the coll ctor main and separating out more or less of the tar in the collector main and then passing the gases through coolers or condensers where the remainder of the tar or oily constituents is for the most part separated. The entire tar 'or oil, separated both in the collector main and in the subsequent coolers or condensers, may be admixed and employed for redistillation according to the present invention; or only the heavier tar may be so distilled or only the lighter tar or oils may be used or tar or oils from another battery of ovens or from another plant may be employed in the process. capacity of the hot coke oven gases is so greatly in excess of the amount of tar or oils which-is normally produced from the gases that a few only of the ovens,-when provided with'the new uptake pipe stills, can distill the tar or oils produced by the rest of the battery, and a larger number of ovens can be employed to distill tar or oils from other batteries or from other plants.

/ The tar or oil to be distilled is supplied in regulated amounts to the spray nozzle and sprayed into the hot coal distillation gases. The tar or oil may be advantageously preheated before being so sprayed. The hot coal distillation gases are brought into intimate contact with the spray of tar or oil and the tar or oil is heatedand distilled by the hot gases, while the hot gases themselves are somewhat cooled. The taror'oil is prevented bafile 8 and collects in the space outside the ipe 7 and runs out through the pitch or residue outlet 11.

. The action of the hot gases upon the particles of tar or oil. spray or upon the tar or oil otherwise brought into intimate contact with them and flowing down over the surfaces of the uptake pipe still, is such that the tar or oil is heated and volatile oils distilled therefrom so that a heavier tar or pitch or residual oil collects and'runs out through the pitch or residue outlet. The distillation can be regulated in the manner hereinbefore described, as by preheating the tar or oil to a greater or less extent before spraying it into the hot gases, or by regulating the rate or character of spray, etc.

The tar or oil may be subjected to a high temperature for only a short period of time. As a result, a low carbon pitch, as compared with ordinary distillation, can be directly produced without any appreciable increase in The distilling carbon content over that normally present in the tar from which the pitch is produced.

Instead of passing the tar once only into contact with the hot coal distillation gases, and recovering a part only of the distillate therefrom, the residue from a first distillation can be redistilled or further distilled by recirculating one or more times through the same still, or through another or other stills, to subject it to further distillation and to produce a heavier distillate and a harder pitch. Instead of producing pitch of low melting point, around 108 F., harder pitches of higher melting point, e. g. pitches melting at 140150 F. (melting point by cube-in-wat-er method) or pitches of melting point around 180 F.. air bath method) or pitch of 212 F. melting point, or even harder pitches can be obtained. By limitingthe amount of tar or pitch sprayed, or by prolonging its contact with the hot gases, its temperature can be raised to the cracking or decomposition temperature of some of its constituents, and its carbon content increased,

thus giving a higher carbon pitch, more comparable to gas house tar pitch. By mixing different tars before distilling them, e. g., coke oven tar and gas house or water gas tar, composite distillates are obtained, and composite pitches.

The gases after leaving the uptake pipe still and while still at a relatively high temperature may be further cooled, for example, by ammonia liquor or tar sprays in the small collector main, before passing to the condensers, or the gases may be passed to the crossover main and to the condensers while still at a high temperature. Depending upon the method of cooling and condensation, the oils from the redistillation of the coal tar, to gether with oil and tar constituents from the normal coal distillation gases employed in the tar distillation, can be obtained in part in the collector main and in part in the subsequent coolers or condensers as relatively clean oils or tarry oils or oily tar containing a greatly decreased content of heavy tar constituents and made up mainly of oils.

When tar or oils are sprayed into the gases in the separate collector main, the heat of the gases will effect partial distillation thereof, and such sprays will further cool and clean the gases, removing some of the heavier tar constituents and increasing their content of oils. In such cases the hot coke oven gases are employed twice, in series, at a higher and then at a somewhat lower temperature, to distill tar or oils, and the gases so employed are twice scrubbed or cleaned by the tar or oil sprays. lVhere the residue from the second or subsequent treatment or treatments is used in the first treatment, the peration becomes counter-current, and the tar or oils are preheated and may be dehydrated as well as partly distilled, by the gases at the lower temperature before further distillation by the gases at the higher temperature. Nevertheless the heat of the gases is such that effective distillation of a large amount of tar or oil can be so effected, while still leaving the gases at a high temperature such that they carry a large amount of condensible oil constituents recoverable in the separate condensing system, tractionally or otherwise. In the operation of the battery illustrated in Fig. 2, most of the ovens are provided with uptake pipes of usual construction which may have ammonia liquor or tar sprays in the goose-neck and in the collector main to separate a considerable amount of heavy tar in the collector main and to give gases of low tar content going to the coolers or condensers. The entire tar product, or only the heavier tar. or only the lighter tar, can then be employed as the tar to be distilled by the process of the present invention, for example, by pa sing the tar to a dehydrator and there dehydrating and preheating it and then bringing the preheated tar into intimate contact with the hot coal distillation gases from the coke ovens so as to utilize the high temperature and heat of these gases to distill the tar.

and produce distillates and pitch therefrom.

The part of the battery thus employed for tar distillation purposes combines in its function that of a coke oven plant for producing coke and coal distillation gases, and the distillation of tar by the hot coal distillation gases, thus combining a tar distillation plant with the coke oven plant and eliminating expense of transportation of the coal tar from the coke oven plant to thetar distillation plant While also greatly reducing plant costand fuel cost for the tar distillation by utilizing the hot coal distillation gases, the heat of which is valueless and which must commonly be removed at large expense.

The products obtained by the redistillation of the tar, according to the present invention, include low carbon pitches or high carbon pitches which may be of varying degrees of hardness. The products obtained by the process also include the distillate oils produced from the distillation of the tar which are admixed with oils and tar constituents from the coal distillation gases employed for the distillation. Where the tar distilled is a complete tar, containing practically all of the tar constituents, a correspondingly wide range of boiling point oils will be produced. lVhere only heavier tar is distilled, the distilled, product will contain a correspondingly increased content of heavier oils. lVhere the tar is recirculated and redistilled, the oils driven off by the rcdistillation will be heavier than those from the first distillation. Vhere the oils from the separate distillations are condensed separately, :1 series of products differing from eaclrothcr can be directly produced by condensation or fractional condensation of the oil vapors from the gases. The invention makes possible therefore, the production of oils of different properties, with low content of heavier coal tar constituents, directly at the coke oven plant.

The uptake pipe andthe circulating lines, etc., are illustrated in the drawings in a conventional manner and without any insulation around them, but where it is desired to prevent loss of heat by radiation, or to reduce such loss, or to prevent undue cooling of circulating lines, etc, such circulating lines, and the uptake pipes and connecting pipes through which the gases and liquids pass, can be provided with heat insulation.

Furthermore, the hot coal distillation gases from the coke oven can be cooled somewhat before bringing them into contact with the tar provided their temperature is still sufficiently high to bring about the desired distillation of the tar and the production of distillates and pitch therefrom. It is advantageous, however, to utilize the hot gases at their maximum temperature, immediately after they escape from the coke ovens, by employing them in the manner described.

While I have described and illustrated a particular type and construction of uptake pipe still,it will be evident that the invention in its broader aspects can be carried out in apparatus of other construction in which the tar or oils are distilled by the hot gases and the distillates separately condensed in the manner described.

I claim:

1. The improvement in the operation of a coal distillation battery in which coal is be ing distilled, which comprises removin the coal distillation gases from a part 0 the ovens or retorts of the batter f and cooling the same so as to separate tar therefrom, distilling tar by bringing it into contact with hot coal distillation gases from other ovens or retorts of the battery so as to separate volatile oils from the tar and produce pitch therefrom, subjecting the gases and vapors resulting from the distillation of the tar to cooling separately from said first-mentioned gases so as to separate distillate oils therefrom, combining the second-mentioned gases after the separation of distillate oils with the first-mentioned gases and subjecting the combined gases to further treatment for the recovery of by-products.

2. The improvement in the operation of a coal distillation battery in which coal is being distilled; which comprises removing the coal distillation gases from the majority of the ovens or retorts of the battery and cooling them to separate tar therefrom, distilling the tar so separated by bringing it into direct contact with the hot coal distillation gases from other ovens or retorts of the battery and separately cooling the gases and vapors resulting from the distillation of the tar to separate distillate oils therefrom.

3. The improvement in the operation of by-product coke oven batteries in the ovens of which coal is being distilled, which comprises removing the coal distillation gases from a part of the ovens of the battery and cooling the same so as to separate tar therefrom, distilling tar by bringing it into contact with hot coal distillation gases from other ovens of the'battery so as to separate volatile oils from the tar and produce pitch therefrom, subjecting the gases and vapors resulting from the distillation of the tar to cooling separately from said first-mentioned gases so as to separate distillate oils therefrom, combining the first-mentioned gases after the separation of tar and the second-mentioned gases after the separation of distillate oils and subjecting the combined gases to further'treatment for the recovery of by-products.

4. The method of producing composite tar products, which comprises distilling coal tar by direct contact with coal distillation gases at substantially the temperature at which they leave the oven and simultaneously separating tar constituents from the gases, the tar present in the gases used for the tar distillation' and the tar beingdistilled being of different character and composition due to their production by different methods of coal distillation, whereby as a result of the distillation of the tar the distillate is admixed with vapors present in the hot gases before the distillation so that mixed vapors are produced, and the residue from the tar distillation is added to the tar constituents separated from the gases during the distillation 50 that a mixed pitch residue is produced.

, In testimony whereof I aflix my signature.

STUART PARMELEE MILLER.

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