US1844891A

US1844891A - Distillation of tar

Info

Publication number: US1844891A
Application number: US166082A
Authority: US
Inventors: Miller Stuart Parmelee
Original assignee: Barrett Co Inc
Current assignee: Barrett Co Inc
Priority date: 1927-02-05
Filing date: 1927-02-05
Publication date: 1932-02-09
Anticipated expiration: 1949-02-09
Also published as: FR648796A; GB284703A

Description

Feb. 9, 1932. s. P. MILLER DISTILLATVION OF TAR 5, 1927 5 Sheets-Sheet l Filed Feb.

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DISTILLATION OF TAR 5. 1927 5 Sheets-Sheet 5 Filed Feb.

m P N VNTOR BY Pm M M M1/f ATTORNEYS .Tm wm Patented Feb. 9, 1932 UNITED l STATES PATENT OFFICE y STUART PABMELEE MILLER, 0F TENAFLY, NEW JERSEY, ASSIGNOR TO THE BARRETT,

I COMPANY, 0F NEW YORK, N. Y., CORPORATION OF NEW. JERSEY DISTILLATION OF TAR `.application and 'February `5, 1927. serial No. 166,082.

This invention relates to improvements in the 'distillation .of tars and the production of pitches and distillate oilstherefroml and includes a new method of tar distillation and of pitch production. More particularly the invention relates to the recovery of desirable products from coal carbonization and gasification plants such, for example, as by-prod' uct coke ovens, illuminating gas retorts, etc.

' The invention will be described more particularly in connection with the operation of by-product coke ovens. Y

In the ordinary operation of by-product coke ovens the gases produced by the coking operation pass from the individual ovens through uptake pipes and goose-necks to a collector main. common to a battery of ovens. The coke-oven gases leaving `the ovens at high temperature are cooled in the collector main and in condensers connected therewith to separate tar constituents therefrom. In many cases the gases are also substantially cooled in the goose-necks by sprays of ammonia liquori The separated coal tar is c ommonly shipped or conveyedto tar distillation plants `where it is subjected to distillation to produce pitches and various other l products.

Owing to the high temperature of the gases from the coke ovens,- and particularly because of the enormous amount of heat carried thereby.' the successful operation of the collector main in connection with these ovens has always been a serious problem. The heat carried by the gases, which leave the ovens at a temperature of approximately 700 C. or higher, is from twenty to thirty-five times `that required for thev distillation of all of the'tar contained in the gases. A certain amount of heavy tar or pitch separates in the collector main and such tar or pitch is subjected to the distlling effect of the gases at high temperature withI the resulting formation in the main of solid hard pitch which can in some cases be removed only by shutting down the plant and scraping or digging it out. It is customary to flush the main with a mixture of tar and ammonia liquor'or with ammonia liquor alone, but this practice does notalways avoid the diiculty. In fact, the

use of Water'or ammonia liquor aggravates the situation in some cases because the pitches formed in the main are insoluble in water or ammonia liquor and hence are not flushed out unless an extremely large amount of the liquor is employed.

'Ihe use of a large quantity of ammonia liquor for flushing the collector main introduces a new difficulty because of the resulting lowered temperature of the gases. Thus, by spraying ammonia liquor into the collector main in sufficient quantity to prevent accumulations of pitch therein, the temperature of the gases may be so reduced that a considerable proportion of the valuable oil constituents which are present in the gases are condensed and are thrown down with the tar and can be recovered therefrom only by subsequent distillation.

It is the object of the present invention to provide an improved process of tar distillation directly at the coal carbonization plant such as a by-product coke-oven plant, and especially an improvement in the operation of the collector main or mains in connection with the by-product coke-oven plant whereby advantage can be taken of the heat carried by the coke-oven gases to distill the tar and separate volatile products therefrom so that the latter can be recovered independently of the pitch which then constitutes a separate product of the operation.

According to the present invention the hot coke-oven gases as. they come from the coke ovens are utilized for the distillation Of tar and the separation of vaporizable oilsthercfrom by bringing the tar into intimate contact with the hot coke-oven gases in the collector main while the gases are at a temperature high venough to accomplish the desired distillation; and pitching ot-.the'nain is prevented by flushing the main'with a large amount of hot tar or pitch excess of that distilled by the hot gases. The large excess of tar or pitch circulated through the main is continually or intermittently drawn off as pitch and can be in part recirculated Y Aas a finished .product or further distilled by ICF,

a separate operation. lVhere a plurality of short collector mains are employed, as hereinafter described, the tar or pitch may be passed in Succession through several of the mains to effect progressive distillation thereof. Pitches having varying qualities and different characteristics, depending upon the regulation of the distillation operation, may be obtained.

The intimate contact of the tar with the hot coke-oven gases results in partial cooling of these gases from the temperature at which they normally escape from the coke oven, e.l g., around 600 to 700 C. or in some cases much higher. The temperature of these gases is sufficiently high and the volume ofnon-condensable gases is so great that the effective distillation of-the tar can be accomplished in the manner indicated. The amount of tar supplied and the intimacy and time of contact of the particles of the tar with the gases and, therefore, the nature and amount of oil distilled therefrom, can be varied. Effective distillation can be accomplished with a temperature drop of the gases while passing through the collector main of, for example, 100 C., 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 attained;

' The tar in turn will be heated by the hot gasesv and its temperature may be very considerably raised. Part of the heat, however,

isemployed in vaporizing liquid constituents of the tar without corresponding `increase in the temperature thereof so that the maximum temperature of thetar and of the resulting pitch may in some cases be considerably below that of the gases. In order to avoid pitching of the main it is important that the tar used to flush the main and that circulating throu h-the main be kept hot so that it is thinly uid Iand so that any pitch formed will be dissolved and blended therein. So long as the pitch is kept sufliciently hot it is thinly fluid and by omitting the cooling effect of excessively large amountsv iis4 of ammonia liquor this thinly fluid condition of the tar can be maintained.

-The distillation of tar in the collector main may be accomplished in a' variety of ways involving the intimate contact of the tar with thegases therein. Preferably the introduction of ammonia liquor to the collector main is avoided except as hereinafter described and in lace thereof the main is flushed with a lsufficient quantity of'tar or oil or tar and oil to ensure against any accumulation of heavy pitch in the main. This object is readily-accomplished ifa suflicient quantity of the flushing medium is provided and if the temperature is kept high because the heavy pitch,

1f it is formed, is soluble in the hot tar or oil used and any-'accumulation will be dissolved and carried along with the stream of hot tar which Hows through the main. The tar or oil or mixtures thereof can be circulated through the main, being introduced at one end thereof and Withdrawn at the other,

or at intermediate points. It is important,

of these purposes can be accomplished by the v provision of suitable mechanical agitating devices within the main and actuated to maintain a constant and violent agitation of the tar as it flows through the main so that the t-ar is splashed or thrown into the stream of coke-oven gases and onto the ex- I posed surfaces of the main, either without or -with the use of spray nozzles, etc., for spraying tar directly on to the surfaces of the main. s

The required agitation can be accomplished'by the use of a rotating shaft running lengthwise of the main or a number of such shafts running-across the .main with suitable paddles thereon or by vertical shafts with similar paddles. Rotating cones or other agitating and splashing devices may be disposed in the collector main and arranged to be actuated 'for the purpose of throwing tar into the stream of gases and upon the exposed surfaces of the main.l Discs, plates or spines on rotating shafts will achieve the same purpose. The required agitation can also be accomplished by the introduction of compressed gases such, for example, as fuel or coke-oven gases or steam through a suitable distributor pipe immersed in the tar or suction Ts (McDaniel type ejectors) may be located in the main ,with their suction ends beneath-the level of the tar therein. If the nozzles of the ejectors are allowed to extend above the surface of the tar a spray of tar will be thrown into the gas. The effect of one or more of the mechanical agitating devices mentioned may be augmented by the provision of suitable spray nozzles in the collector main and goose-neck through which tar may be sprayed into the stream of gases flowing through the main.

Although indiscriminate cooling of the gases-in the collector main as heretofore practiced is to be avoided, it may be desirable to introduce water or ammonia liquor with the tarwhich is sprayed into the collector main to cool the gases to a predetermined and regulated extent. The regulation of the cooling effect' can be accomplished more readily with water becauseof the higher specific and latent heats of water as compared with tar' made available, where this is desired, by

passing such gases over the incandescent surface of the coke in the ovens and thence through the uptakes to the collector main. The distilling capacity of the gases from a single coke oven battery is greatly in excess of that required for the distillation of he, amount of tar Which that single cokeoven battery produces so that the tar from a considerable number of coke-oven batteries can be distilled by the hot gases from a single battery. Consequently, to maintain the operation as hereinbetore described, it is ordinarily necessary to provide an amount of tar very much in excess of that produced by the single battery which is so operated or the volume of the gases used should be reduced to that which will distill the available tar, as, tor example, by using such gases in a sepa rate short collector main.

W here several coke-oven batteries are operated at a single plant, e. g., twenty batteries, the tar from several or all of the batteries can be distilled on a single battery by operation according to the present invention. `Where there is only one or a few batteries the tar can be recovered in normal operation, e. g., With ammonia liquor sprayed in the collector main, and after a suflicient amount of tar has accumulated it may then be distilled in the collector main by operating one or more days in the manner described. lt continuous operation with a relatively small amount of tar is desirable,vthe light or heavy oil from the condensers can be returned to the main in suitable proportion to the tar which is circulated. Such operation may be desirable when there is no provision for the accumulation of large stocks of tar.

Instead of carrying on the distillation in the collector main which is common to all of the ovens of the battery, a short collector main may be provided and connected to a few only of the ovens so as to receive the gases from those ovens while the gases from the remaining ovens pass through the large collector main. The ovens which are connected to the short collector main may also be connected with the large collector main and suitable valvcs may be employed to direct the gases through one or the other of tlie'mains as may be desired. The short collector main may be suitably disposed either below or above or alongside of the large collector main or it may be placed at the opposite side of the battery. Instead of providing a long and a` short collector main there may be a series of short .collector mains, each connected to a number ot the ovens of the battery so as to receive the gases from those ovens. In either arrangement the short collector mains may be provided with the mechanical agitating means to ensure the intilnate contact of the tar or oil with the hot coke-oven gases lloWing through the mains. The effect of mechanical agitation can be increased by the provision of tar sprays in the collector main and in the goose-necks leading thereto. lVherc separate short collector mains as hereinbct'ore described are provided, the gases leaving the short main or mains may be conveyed to separate condensing apparatus or into the collector or cross-over main or directly to the condensing apparatus which receives the gases from the large collector main. The condensing apparatus employed may be of the direct or indirect type and may be designed to permit fractional condensation of the condcnsable constituents in the gases.

The tar which is distilled according to the present invention may be tar produced at the same coke-oven plant or at another plant. The tar may be heavy tar, light tar or heavy or light tar constituents which it is desired to distill for the purpose of separating` distillate oils therefrom. Other tar such as gas-house tar, vertical retort tar or watergas tar, etc.. can also be distilled, or light tar or tarry oils, etc. Where blended or composite pitches are desired or composite or blended distillates two or more ditlerent kinds of tar can be distilled separately at the coke-oven plant orthey can be admixed in suitable proportions and can be distilled t0- gether, giving directly a composite pitch product. lVhere dill'erent tars are distilled the resulting pitches can be blended to give a composite product and the distillates can likewise be blended when desired. For example, horizontal gas-retort tar with high free carbon content can be admiXed with cokeoven tar and the mixture can be 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 condensable oils or it may be a heav tar containing only part of the oils. here mixed tars are distilled the condensates will be of a composite character. Where ditl'erent tars are separately distilled the gases and vapors 'from such separate distillations can be condensed separately or together'.

Tar. as commonly produced and collected at coke-oven plants contains more or less water or ammonia liquor admixed therewith. Such tar can be empio-*ed directly an'ddehydrated as well as distilled or it'can be partially or completely dehydrated before ist subjecting it to distillation. The tar can also be preheated in any suitable manner to reduce it to a thinly fluid state which will facilitate the mechanical agitation of the tar and ensure intimate contact thereof with the hot coke-oven gases. The amount of heat contained in the hot coke-oven gases is, however, so great that effective dehydration as Well as distillation can be accomplished readily and preheating the tar by separate preheating means will not usually be necessary.

In carrying out the process the tar may be brought into contact with the hot gases only once or it may be recirculated and brought again into contact with the hot gases to accomplish a further distillation and the production of harder pitches or even pitches of modified character such as those having increased free carbon content. This further distillation may take place by recirculating the tar or pitch through the same collector main or through another or other systems as, for example, successively through a series of short collector mains, so that distillates and pitches of the same or similar character are produced in different systems or distillates and pitches of different character in the different systems. By regulation of the agitation of the tar and by redistillation when necessary, it is possible to regulate the hardness of the pitches produced and to produce softer or harder itches as desired. The further distillation o the pitch first produced to recover additional oil t erefrom can be carried out in the collector main or in other distillation apparatus. By providing separate collector mains, each connected to a series of ovens, it is possible to produce distillates and pitches o different characteristics simultaneously and b operating separate condensing systems `vit such separate distillation systems condensed products having different properties can be produced simultaneously. f

The 'present invention includes not only the distillation of tar for the production of distillate oils therefrom but also the production of pitches of var ing properties and characteristics. By limiting the time of contact of the tar with hot gases and the temperature to which the tar is raised during distillation. pitches of low carbon content and oils of definite characteristics can be produced as hereinbefore described. When, however, the pitch first produced is recirculated, its temperature will be further raised and the temperature can be increased to such an extent that more VVor less decomposition will take Kplace with resulting formation of the materials commonly known as free carbon, thus increasing the free carbon content of the pitch. It is thus possible by recirculation of the pitch and by regulating the agitation of the tar in the collector main so that the pitch is kept in contact with the hot gases for a sufficient time to raise its temperature to the decomposition temperature to decompose or crack greater or less amount of the pitch and/or oil constituents and to produce a corresponding amount of free carbon in the product.

In addition to producing pitches of different properties and characteristics the resent invention permits the production ofp distillates from tar or tar fractions or oils. Consequently it can be employed to distill a dirty oil or an oil contaminated With tar or pitch, to produce a cleaner distillate oil therefrom and a pitch residue. In systems Where separate short collector mains are connected to separate condensing systems,l each systemr may be supplied with a different material, for example, one may distill tar in the manner described and another may distill a mixture of oils for the separation of the different oil constituents therefrom.

The gases escaping from the collector main operated in the manner hereinbefore described contain considerable quantities of vapors or oils derived from the distillation of the tar together with the usual fixed gases. The gases being still at a relatively high temperature in order that the oils may be retained in vapor form and thus separated from the pitch, may he subjected to any subsequent desirable treatment for the purpose of effecting the separation of the oil in fractions. Preferably the gases are withdrawn from the centre box of the collector main independently of the pitch circulating therein and are conducted through a cross-over main to the separation apparatus. If it is desired to cool the gases rapidlyto a temperature necessary for the separation of one or more of the heavier of the volatile constituents, the gases may be sprayed in the cross-over main with ammonia liquor or oil or mixtures thereof and the resulting liquid can be conveyed to a decanter in order to separate the ammonia liquor from the condensed tar or tarry oils.

Instead of cooling the gases and vapors rapidly they may be cooled progressively to effect a fractional condensation of the vapors to yield oil fractions of definite character. The large increase in condensable vapor content of the gases due to the distillation of the tar thereby results in the recovery of a relatively greatly increased amount of light tar and oil products While the scrubbing and ,purifying effect of the tar on the gases gives relatively cleaner oil products than are normally obtained with ordinary by-product condensing systems. The 'present invention is of more or less general application to the distillation of tar and oils and the recovery of distillates. The invention involves utilization of the hot cokeoven gases for the distillation of tar or oil by bringing the tar or oil into direct contact therewith. The invention will be further illustrated by the following more detailed description which should be read with the accompanying drawings showing ap aratus adapted for the practice of the invention, but it is intended and will be understood that the invention is not limited to' specific details of the apparatus as illustrated in the drawings; in which i n l is a plan view of a portion of a coke oven illustrating the application of the in` vention thereto;

Fig. 2 is an end elevation, partially in section, of the structure illustrated in Fig. 1;

Fig. 2a is a sectional view through the center box taken on the line 2a2a of Fig. 1;

Fig. 3 is an enlarged sectional view illustrating the agitator in the collector main;

Fig. 4 is a sectional view illustrating a different form of agitator;

Fig. 5 is a similar view showing'another form of agitator;

Fig. 6 is a sectional view illustrating the application of the suction T in the collector main;

Fig. 7 is a plan view ofthe coke oven with a short collector main;

Fig. 8 is a plan view illustrating the application of multiple short collector mains to the battery; and

Fig. 9 shows a modified arrangement.

Referring to Figs. 1 and 2 of the drawings, 5 indicates a battery of coke ovens having individual uptake pipes and goose-necks 6 which connect the ovens with a collector main 7. The latter is designed to receive all of the gases from the individual coke ovens and to deliver them through a modified centre box 8 to a cross-over main 9 which is connected to the condensing apparatus hereinafter described. The centre box is constructed and arranged so that a substantial depth of tar or pitch is maintained therein and in the collector main. as illustrated in Fig. 2a, and the centre box is shown as larger than usual so it will hold a considerable body of tar ory pitch. lt may be provided with insulation (not shown).

The collector mainis provided with a longitudinally extending shaft 10 having a plurality of paddles or arms 1l distributed throughout its length. The shaft is adapted to be driven through any suitable mechanical connection with a suitable source of power. A pipe 12 is connected to the collector main, for example, at one end thereof and a pump 13 is provided to force tar or pitch from a receptacle 14 to the collector main. If desired, the tar or pitch may be distributed to the collector main :it a plurality of points through suitable pipes provided for that purpose and it may be introduced, if desired, througli spray nozzles` 15 and 16 connectr d to such pipes in such a way as to permit the spraying of the tar or pitch into the collector main.

The pitch which accumulates in the bottom of the collector main is withdrawn either continuously or intermittently through a pipe 17 and may be recirculated through a pump 18 and the pipes hereinbefore described or the pitch can be withdrawn through a pipe 19 and delivered to a receptacle 20.

As hereinbefore described, the operation of the collector main involves the maintenance therein and the circulation therethrough of a sufficient quantity of tar or pitch to prevent the accumulation of hard pitch on the bottom andexposed surfaces thereof. The pitch is withdrawn continuously or intermittently through the outlet pipes and is either returned or is partly returned and partly replaced by tar or pitch from other sources. The effect of the agitator in the collector main is to throw the tar or pitch in a finely divided condition into the stream of gases which pass therethrough and the tar or pitch is thus subjected by reason of its subdivision to intimate contact with the hot gases. This intimate contact effects a substantial distillation of the tar or pitch to produce a harder pitch which, however, is carried along by the stream of tar and pitch in the bottom of the collector main and is prevented thus -from accumulating and blocking the main. The tar or pitch is likewise thrown in finely divided condition onto the exposed surfaces of the main and flushes its surfaces. therefore, and prevents accumulation of hard pitch thereon. l

Because of the distilling effect of the hot coke-oven gases, these gases accumulate a considerable proportion of volatile oils which are distilled from the tar or pitch and these volatileoils remain in the` gases at the temperature at which the collector main is op# erated. for example. a temperature of from 100 C. to 200O C. lower than that of the gases escaping from the coke ovens. The intimate contact between the gases and the tar or pitch in the collector main serves another important purpose in that it washes from the gases the more readily condensable tar constituents thereof, while still leaving a considerable proportion of the normal volatile constituents ,in the gases. It further washes from the gases to a greater or less extent much of the entrained solid material such as free carbon, etc. The gases are thus not only enriched in the more volatile constituents but are freed to some extent from insoluble and heavier entrained materials.

As hereinbefore indicated, the ei'ect of the mechanical agitator in the collector main may be augmented b v introducing all or a part of the tar in the form of spray through spray nozzles provided for that purpose. These spray nozzles ensure the subdivision of the tar into minute particles and facilitate contact, therefore, between the hot coke-oven gases and the tar particles with resulting improvement in the distilling effect.

The gases which escape from the centre box 8 to the cross-over main 9 carry therewith a large proportion of the volatile constituents of the tar which enters the collector main and are to a considerable degree freed not only from heavy tar constituents which are not volatile at the temperature of operation of the collector main but also from insoluble entrained matter. These gases may be subjected in the cross-over main to contact with ammonia liquor delivered thereto through a plurality of spray nozzles 2l supplied by a pipe 22 from any available source of ammonia liquor in the system. From the crossover main the liquid containing any tar or oil constituents, together with the ammonia liquor` is delivered through a pipe 23 to a decanter 24 in which the ammonia liquor can be separated and returned, for example, through the receptacle 25, pump 26 and pipe 22 to the crosspver main. The tar or oil from the devant-.er is delivered through a pipe 27 to a receptacle 28. A pump 29 and pipe 3() permit delivery of tar or oil to the pipe 22 and the tar can be mixed with ammonia liquor employed as a cooling agent in the crossover main. A pipe 3l connects the receptacle 24 with the tar receptacle. Tar from. any other sour can be delivered to the receptacle 14 through a pipe 14.

The balance of the gases still containing oil constituents are delivered to condensers 32 wherein the available oil products are separated and from which they can be withdrawn to a decanter for Iseparation of ammonia liquor from the oil. The, gases which escape from the condensers are withdrawn through an exhauster 34 which ensures the movement of the gases through the system.

As hereinbefore indicaiM. the primary object of the present invention "s the distillation of tar and the recovery ot' volatile constituentsI therefrom at the coke-oven plant and thi` utilization oi` laat in the y:fases eshe col".l` )in advantage i in coni fr iecior no: and

raping; gnrom the mechanical agitating means in the collector main. In this case a plurality of vertical shafts 35 are disposed in the collector main 36, each shaft carrying a numberof cones 3T. The shafts are adapted to be actuated through any suitable source of power such as a small electric motor. lVhen the shafts are rotated the cones which are immersed in the stream of tar in the bottom of the collector main throw the tar upwardly and in a finely divided form into the hot coke-oven gases which enter the collector main from the coke-oven battery 39. It is understood that the body of tarv or pitch is maintained in the collector main as in the preceding embodiment of the invention.

In Fig. 5 of the drawings a shaft 40 extending longitudinally through the collector main 41 carries a plurality of discs 40. The shaft 40 can be driven from any suitable ,source of power to cause the discs l0 to rotate in the body of tar or pitch in which they are immersed in the collector main. The rotation of the discs causes a spray of tar or pitch to be thrown into the stream of hot coke-oven gases which enter the collector main through uptake pipes` l2 from the battery of colte ovens 48. Yl`l1is structure thus provides for the intimate mingling of the tar or pitch with the hot colic-oven gases to accomplish the distillation of the tar in the manner hereinbefore dcaprbed. lt is understood that the supply of tar orl `pitch in the collector main may ne maintained as hereinbefore described.

Referring to Fig. t5 ol' the drawings a plurality of injectors Llll may be connected to a. pipe 45 extending longitudinally through the collector main and adapted to be supplied with any suitable gas such as fuel gas, colteoven gas: steam or the like. under pressure sufficient to Vproduce ctl'cct ive suction and injector action when the ics passes through Rill the injectors. The sin ride of the injectors maj; in innncrsm- .e tar or pitch in the bottom al" iin as shown and when s supplied in iai: or pitch will .l f lv n n 11am of a spray Y' l entire space p :allector main w i; g subjected to i lie-oven gases 4T from the supply of tar y the collector l l o illf'l'lllC-ii. 'lV ,le invention al collector' n. Thus if f :"dxtiYcly l hert ai' thc wenl with the mann.v

l direte-f the usual uptake pipes and goose-necks l which communicate with the collector main 52 having a centre box 53 from which' the gases and the condensate are delivered to a cross-over main 54 leading to the usual condenser system including the condensers The gases are drawn through the system by an eXhauster 56. .The separated tar and ammonia liquor may be withdrawn through decanters (not shown) as in the usual practice. The structure so far as described is the ordinary arrangement and in the operation of this apparatus ammonia liquor in suitable quantity may be delivered to the collector main for the purpose of cooling the gases therein. Y

To permit the practice of the invention as herein described, a short collector main 57 may be disposed alongside of or above or in any suitable relation to the usual collector main, but is arranged preferably at the rear of the ovens and is connected to a plurality of such ovens by uptake pipes 58. Valves may be provided to permit direction of the gases from the ovens into either of the collector mains. The short or` auxiliary collector main is designed for the distillation of tar in the manner hereinbefore described and is provided, therefore. with an agitator as shown, for example, in Fig. 3. The agitator may be of any of the forms hereinbefore described or their equivalents. The agitation of the tar or pitch results in throwing the latter 1n the form of a spray into the hot coke-oven gases delivered thereto from the uptake pipes, and the tar is consequently7 distilled. The tar and resulting pitch may be circulated as in the similar operation of the usual collector main. The tar or pitch can be withdrawn continu- `)usly or intermittently through a pipe 6l and returned by a pump 62 through a pipe 63 or it may be delivered through pipe 64. to a receptacle 64. Fresh tar or pitch can be introduced through a pipe 59.

The gases from the short' or auxiliary collector main are withdrawn through a main 65 and delivered to condensers 66. These can be arranged in series and may be fractional condensers of either direct or indirect type to permit recovery of two or more ditllcrentoil or tarry oil products from the gases leaving the short collector main. The condensates from the condensers are withdrawn and delivered to Suitable receptacles. The remaining gases may then pass through a pipe (57 to the exhauster which maintains the proper balance of pressure in the, system.

In Fig. 8 of the drawings l have illustrated another arrangement in which a plurality of short collector mains replace the usual collector main, each short collector main being connected to a plurality of uptake pipes so that the gases from a selected number of ovens can be utilized for the distillation of tar. This permits great flexibility in the capacity of the plant for tar distillation since one or more of the short collector mains can be utilized for that purpose while the remaining collector mains are operated in the usual way.

Referring to the drawings, the coke-oven battery is provided with the usual uptake pipes and goose-necks 71 which communicate with a number of short collector mains 72, each having a. centre box 73 from which the gases are delivered to a cross-over main 74 leading to the usual condenser system including the condensers 75. The gases are drawn through the system by an eXhauster 76. The separated tar and ammonia liquor may be withdrawn through decanters as in the usual practice. The structure so far as described permits operation in the usual way.

The apparatus is designed, however, as hereinbefore indicated, to permit the distillation of tar in one or more of the short collector mains and for that purpose each may be provided with a suitable agitating device such as hereinbefore described, for example, a shaft with paddles thereon as shown in. Fig. 3 and adapted to agitate the tar or pitch in the collector main and to throw it into the stream of hot coke oven gases passing through the main. Each collector main may be provided moreover with circulating`line 80 and pump 82 to permit recirculation of tar or pitch through the main together with inlet lines 84 for the introduction of such additional tar or pitch as may be necessary to permit the maintenance of the intended operation. Outlet lines 8l are provided by means of which regulated amounts of the tar or pitch can be drawn off or circulated into the next. collector main, depending upon the regulation of the valves. The pipes Sl con necting the short collector main permit the pitch produced in one end to be pumped to the next main and from that main to the next in a continuous manner, whilethe tar or pitch can be recirculated to a greater or less eX- tent through the individual mains. In this way, a progressive distillation of the tar and pitch can be effected with the taking off of progressively heavier vapors and the production of. progressively heavier pitches.V Part or all of the pitch produced in the individual collector mains may be drawn off as products of the distillation. If no tar is introduced except at the short collector' main at one end of the battery. and if the tar is circulated and distilled in this main and the pitch then conveyed to the second main and there further circulated and distilled and the residue then to the third main and further circulated and distilled. the haidest pitch will be produced from the last main and the vapors driven otf will be progressively heavier. The arrangement ot' Fig. t5 howeverprovides for operating the individual short main separately without discharging the tar or pitch from one main to the other, and in that case products of the same or different properties may be produced in the different mains, depending upon the amount and character of the tar supplied and the extent to which it is circulated and distilled. The character of the operation in the different mains can be further modified by supplying additional tar or pitch to the individual mains through the pipe 84.

Each of the collector mains of Fig. 8 may be provided with a separate condensing system, for example, a series of condensers 83, designed to separate different oil fractions from the coke oven gases and vapors resulting from the distillation of the tar or pitch. It is to be understood that suitable ,valves will be included to permit the direction of the gases into the separate condensing system or into the primary condensing system for the battery asma-y be desired. By providing a series of separate condensing systems, it is possible to produce distillate oils of different properties from the admixed gases and vapors from the different short collector mains, particularly where these mains are operated in series or under different conditions so that pitches of different characteristics are produced in them and so that the vapors distilled oftI likewise vary in their characteristics. By regulating the distillation and condensation, it is possible to obtain directly by condensation a series of condensed products of differing properties and characteristics.

A modified arrangement is illustrated in Fig. 9 which shows the top of part of one side of a battery in elevation with three short collector mains 85 arranged atprogressively different levels, each being connected with a series of four uptake pipes 88 and each having an'individual centre box 86 and crossover main 87, each having agitators 89 therein for atomizing or spraying the tar or pitch into the gases passing through the main.

Individual supply pipes 90 are provided for each of the individual mains so that tar or pitch can be supplied to all of the mains i if desired. Each main is also provided with circulating

lines

91, 93 and 94 and circulating pump 92, and with a discharge line 95 for discharging the pitch residue from the main. The short mains are connected with overflow lines 96 by means of which the pitch can be permitted to overflow from one short main to the next main at a lower level and thence to the third main from which the pitch may likewise be permitted to overflow through the line 97. By means of the overflow pipes 96 and the valves therein, it is possible to permit a greateror less amount of the pitch to flow from one main to the next so that the pitch from one main can be, in whole or in part, discharged into the next, and the residue from the secondinto the first, etc., thus making possible the production and withdrawal of different kinds of pitch from the separate short mains and also making possible the production of heavier distillates from the separate mains. Additional tar can be introduced into the respect-ive short mains if desired, to modify the operation and the products produced, or all of the tar can be introduced into one main and the residue caused to flow progressively through thek other mains. The individual condensing sysf tems, such as are illustrated `in Fig. 8 are not shown in Fig. 9./

The arrangement as described permits the operation of the coke oven in the usual manner and the utilization of a portion of the heat in the hot ycoke-oven gases for the purpose of distilling tar derived from the gases issuing from the other ovens of the battery or tar from other sources. As in the tar distillation in the usual collector main as previshort collector main or mains with a quantity of hot tar or pitch suflicient to prevent accumulation of` hard pitch in the main or mains. The apparatus as described, including a short collector main or mains, is particularly useful where the quantity of tar to be distilled is relatively limited and insufficient to permit proper flushing of the usual large collector main. It can be utilized, therefore, at isolated coke-oven plants where a single `battery of coke ovens is operated and Where the quantityof tar obtainable from other sources 1s relatively limited. It permits the production of pitch having the desired characteristics and the recovery of valuable oils from the tar in a simple, effective and economical manner.

The advantages of the invention have been set forth in some detail and the preferred embodiments have been described. It is to ,ously described,itV is lessential to lflush the be understood, however, that various changes i In the accompanying claims I use the term tar to include not only rawA tar but also the partly distilled tar or tarry oils which are introduced linto the main and atomized or sprayed into the gases and distilled thereby.

l claim 1. The improvement in the operation of coal distillation plants with distillation of tar and production of pitch and oils therefrom and from the coal distillation gases, which` comprises conveying the gases from a plurality of the ovens or retorts to a collector mainrab'ove the surface of the tar while the gases contain substantially the same Avapor content as when they left the ovens or retorts and are still at a temperature sulficiently high to effect rapid distillation of tar and not greatly below that at which the gases leave the ovens or retorts, continuously introducing into the said main a quantity of tar many times in excess of that contained in Such gases and causing the tar to be distributed from the body thereof in the bottom of the main into the coal distillation gases in the form of spray which scrubs the gases and l0 washes the exposed Walls of the main to prevent the carbonization of pitch thereon, whereby it is brought into intimate contact with such gases in a finely divided state to effect rapid distillation of the tar and to scrub the gases so that the gases are considerably enriched in oil vapors and cleaned by the scrubbing treatment, continuously removing from the main the gases and vapors resulting from the distillation and cooling the same to condense oils therefrom and withdrawing from the main the residue from the distillation.

2. The method of distilling tar and of producing pitches and distillate oils therefrom and of simultaneously producing pitches and oils from coal distillation gases, which comprises conveying the gases from a plurality of coal distillation ovens or ret-orts, while at a sufficiently high temperature to eii'ect rapid distillation of tar, to a collector main, maintaining in the main a continually changing body of tar and pitch, introducing the gases into the main above the body of tar and pitch therein, continuously introducing into the main the tar to be distilled in an amount several timesv that normally contained in the gases passin through the main, subjecting such body o tar and pitch to violent agitation to atomize or spray the same into the gases and against the walls of the main above the body of tar therein to effect rapid distillation of the tar and simultaneous scrubbing and rapid cooling of the gases and washing of the exposed sides of the main, so as to prevent the carbonization of pitch thereon, whereby pitch is scrubbed from the gases and combined with the body of tar and pitch at the same time that the tar is rapidly distilled and the resulting oil vapors are combined with the gases passing through the main, passing the resulting gases an vapors to a condensing system to condense oils therefrom, and drawing' olf the resulting pitch from themsin.

In testiml ny whereof I ai-x my signature.

STUART PARMELEE MILLER.