US1942374A - Process of distilling tar and recovering oils with apparatus therefor - Google Patents

Description

s. P. MILLER 1,942,374

PRocEss oFQ'DIsTILLING TAR AND RECOVERING oILs WITH APPARATUS .THEREFOR Jan. z, 1934.

Fiied Aug. s1, 1929 4 sheets-sheet 1 INVENTOR WM M ATTORNEYS Jan. 2, l11934. 41,942,374"

PaocEss oF nIsTILLING TAR AND REcovERING oILs WITH APPARATUS 'x'HEREiFc-m"l S. P. MILLER -4 Sheets-Sheet 2 Filed Aug. s1, 1929 warum Y if,

ATToRNEYs Jan. 2, 1934. s. P. MILLER 1,942,374

PROCESS OF DISTILLING TAR AND RECOVERYING! OILS WITH APPARATUS THEREFOR Filed Aug. s1, 1929 4 sheets-sheet 3 fa fara af fa fafa far q/ feeq' v 3:)

s 1 f d ATTORNEYS PROCESS OF DISTILLIG TAR AND RECOVERNG OILS WITH APPARATUS THEREFOR s. P. MILLER FiledvAug, s1, 1929 4 SheetsSheet. 4

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fnde/15er C22/)Jouer INVENTOFQA WM M 1 BY 7 ,/amwwu ATTORNEYS Patented Jan. 2, 19.34 I

UNITED STATES PATENT OFFICE*` PROCESS OF DISTILLING TAR AND RE- COVERING OILS WITH APPARATUS THEREFOR Application August 31, 1929. Seal No. 389,644 13 Claims. (Cl.` 202-30) This invention relates to the distillation of tar in hot gases, for example, hot coke oven gases or other hotv coal distillation or gasification gases to produce a high melting point pitch with rectication of the resulting distillate vapors.

When tar is distilled to produce a high melting point pitch, i. e., a p'tch with a melting point of 300 F. or 400 F. or higher, and the distillation is carried out under conditions which tend to prevent decomposition of the tar' constituents, the distfllate obtained will contain higher boiling constituents' which are solid or semi-solid in an isolated state at ,ordinary temperatures.

It is an object of this invention to provide for the distillation of tar in hot gases and the recovery of a condensate. including o'ls of high boiling range but free from such higher boiling solid or semi-solid constituents and also for the recovery of a fraction of higher boiling range containing a high percentage of such constituents. Where a fraction of ths higher boiling range rich in such constituents is desired, the high boiling fraction recovered by the rectification process of this invention may be collected separately as a separate product of the operation. Where oils free from such higher boiling constituents are desired, the fraction containing such higher boiling constituents removed from the distillate may be separately collected or it may be returned to the still to be subjected to redistillation, or it may be returned to the still and be drawn off with the pitch produced therein.

It is an object of the invention to provide for the return of a fraction of higher boiling con-stituentsrecovered from the gases and vapors resulting from thedistillation of tar with hot gases, to the still, either to subject that fraction of the condensate to redistillation or to blend it with the pitch produced in the still' to form a composite pitch product within the still.

According to the present invention, tar is distilled to pitch by direct and :'ntimate contact with hot gases such as hot coke oven gases in the form of a ne spray, and Where the gases employed for the distillation are pitch-ladengases, i. e., gases such as coke oven gases which contain pitchy constituents in suspended form, the tar is sprayed into the gases inthe form of an in'- tense spray which not only eects dist'llation of the tar but simultaneously detars the gases. 'I'he gases and vapors resulting from this formation of pitch are passed thru a rectifying column and then cooled and where desired, fractional cooling of the gases may be employed to produce two or more oil fractions. Condensate from this cooling of the gases is advantageously employed as the rectifying medium and where two or more d'stillate fractions are recovered from the gases leaving the rectifying column, distillate of the highest boiling range is employed to advantage as the, rectifying medium. The rectification is' so controlled as to fractionally condense in the rectifying column vapors of a particular boiling range and to remove them as liquids from the base of the lfrac'tionating column. In removing in theA rectifying column constituents which are semi-solid or solid in an isolated state, precautions should be taken to insure that the fraction 'removed from the bottom of the rectif-ying column is maintained in a liquid state, andnot allowed to solidify in the draw-off. This is done preferably by maintaining the'draw-oii from the rectifying column at a suiicently high temperature to keep the condensate liquid. According to this invention the rectication and subsequent cooling of the gases is controlled to remove constituents of a desired boiling range in the rectifying column and on subsequent cooling of the resulting gases and vapors to yield a distillate fraction `or fractions free or relatively free from constituents of this boiling range.

When, for example, it is desired to collect as a separate fraction .the high boiling solid or semisolid resinous or greasy constituents which are volatilized from tar in the production of a high melting point pitch, these higher boiling resinous or greasy constituents are removed from the gases in a rectifying column before the gases are cooled for the recovery of other fractions of condensate and the oil vapors passing fromthe rectifying column with the hot gases will be relatively free from vapors of these higher boiling constituents. On cooling, oils substantially free from these higher boiling constituents will be obtained, and they can be recovered as one oil or by a. stepwise cooling ca'n be recovered as several oil cuts, for example, as creosote oil and tar acid oil.

The degree of distillation of the tar, the amount and characteristic of the reux supplied to the rectifying column and other factors commonly known to those skilled in the art may be regulated to produce a high yieldof oils including oils of higher boiling range, but free or substantially free from thesesolid or semi-solid constituents, as desired. Either oils free from thehigher boiling constituents or the higher boiling constituents `l ,which are solid or semi-solid in an isolated state CIS lected, according to the process of this invention.

According to a preferred method of carrying out` the invention, the distillation of the taris eiected at a coal distillation orother coal gasication plant andthe heat of the hot coal gasication gases is employed for effecting the distillation. The gases are used at substantially the temperature at which they leave the. ovens or` `isolated state at ordinary temperatures. The

distillation in the still is eiected in such a manner that the gases leaving vthe still contain such higher boilingl constituents and in such a way that these constituents are not decomposed in the still. To accomplish this, the tar is brought into direct and intimate contact with the gases in the still, preferably in the form of a fine intense spray in which state the tar is subjected to the action of the hot gases for only a relatively short period of time and the gases are rapidly cooledand the tar is rapidly vaporized so that the pitch residue remaining from the distillation is rapidly brought into equilibrium with the partially cooled gases.

The distillation may be carried to the point where a'pitch with a melting point of 300 F. 012.400 F. or higher is produced and the gases may leave the still at a.' temperature of 325 C. or higher. After leaving the still the gases and vapors pass up thru a rectifying column, which may, for example, be of the ordinary packed type, and then to condensers. Any suitable oil may be employed for the rectification. Preferably oil condensed from the gases after they leave the rectifying column is returned to the rectifying column to effect the ,rectiication i i The lower boiling constituents of the, oil sprayed into the rectifying columnare vaporized and higher boiling constituents present in the `gases are simultaneously condensed and separated from the gases. The rectification separates the higher boiling constituents from the vapors of lower boiling oils which pass over from the rectifying column into the condensers. `'Ihese higher boiling constituents may be separately collected asa separate high boiling fraction or they may be returned to the still and be subjected to redistillationI therein,

be used in any desired way.

In order to produce a high melting point pitch,

i. e., a pitch with a melting point of about 300, F.-

- pitch immediately before being withdrawn from the still is sprayed into the somewhat cool and partially saturated gases. lTar may be distilled to a high melting point pitch' in this manner without objectionable coking of the pitch. The distillation may be carried on in two stages. In the ilrst stage of the distillation tar is brought into ldirect contact with the hot gases and vapors from the second stage of the distillation and asemipitch is produced. During this stage of the distillation partially saturated gases of a'relatively low temperature are employed for the distillation or they may be blended' with the pitchproduced in the still, or they may and the tar and gases advantageously ow n countercurrent direction. In the second stage of the distillation semi-pitch from the rst stage is Kdistilled to pitch of a high melting point. The

semi-pitch in the form of an intense spray is sprayed into the fresh hot gases and distilled therein. In this stage of the distillation the hot gases and the semi-,pitch are advantageously passed thru the still ina concurrent direction. The semi-pitch is sprayed and resprayed into the gases. 'The high melting point pitch produced is withdrawn from the still at theend of thestill at which the gases and vapors pass from the second stage of the distillation to the rst stage of the distillation. It is to be understood that the invention is not limited to this method of distillation or to distillation inthis type of still, but that other stills and other distillation processes may be employed..

When the high boiling constituentsfrom the rectifying column are added to the still to be blended with the pitch and to be drawn oi from the still blended therewith as a composite blended product, these constituents are advantageously added to the still at or near the point where the pitch is drawn oi from the still. Where .these constituents are returned to the still for redistillation they are advantageously added to the still at a point remote from that at which the pitch is drawn off of the still and may advantageously be added to the still at the same point as the tar, or as the semi-pitch when two-stage ldistillation is employed.

' Where coke oven ygases or other pitch-laden gases are employed for the distillation, the tar is sprayed into the gases in the still in the form of` such a ne intense spray that the gases are scrubbed and detarred simultaneously with the distillation of the tar, and the pitch thus removedv from the gases is 'combined with the pitch residue from the distillation to give the high melting point pitch product of the process. The condensate recovered from the gases leaving the still is a clean condensate, so that both the higher boiling fraction separated from the gases in the rectifying column and .the'oils subsequently recovered from the gases are free or substantially free from tarry or pitchy constituents.

In the drawings, one arrangement aof a still in connection with a coke oven battery and means for rectifyingthe distillate is shown in more or less detail. The drawings also include a schematic showing of this arrangement and modined arrangements'for accomplishing rectification according to other processes embraced by this inve'ntion.l It is to be understood that the drawings illustrateh'the invention but that the invention is not limited thereto. In ythe drawings- Fig. 1 is a plan \view of a coke oven plant equipped for carrying out the invention;

Fig. 2 shows an elevation of the apparatus of Fig. 1;

Fig. 3 is a section thru the still on the line 3-3 of Fig. 2; y

Fig. 4 is a schematic showing of the apparatus shown in greater detailv in Figs. 1-3; .and

Figs. 5-9 are similar schematic drawings of modied adaptations of the invention.

In Fig. l, 5v indicates a coke oven battery, the ovens of which areconnected with the collector main 6 thru uptake pipes and goose necks 7. A

At the rear of the ovens is a still 10. The hot coke oven gases from selected ovens of the battery pass up thru uptake pipes and goose necks 11 and thru the hot gas header 12 into this still l0. By the proper manipulation of valves in the uptake pipes 11 and the uptake pipesA 7, gases from the selected ovens may be passed either to the collector main 6 or thru the hot gas header 12 into the still l0. From the still the gases pass thru the hot gas saturator 11' up thru the openingl2' into the rectifying column 13. The uptake pipes 11, the hot gas header 12, the still l0 and the saturator and rectifier ll and 13 are advantageously insulated as at 40 to prevent loss of heat by radiation.

The tar to be distilledis sprayed into the hot gas saturator thru the nozzle 14. It passes down over the baille 15 to the bottom of the saturator where the partially distilled tar` is collected and drawn off thru the line 16 and fed into the end of the still at which the hot gases enter. In the still is a roll 17 partly immersed in the tar and pitch in -the still and adapted to be rotated at high speed, forexample, 900-1200 R. P. M. by the motor 18. This roll sprays the partially distilled tar or pitch up into the hot gases as an intense spray; distillation is effected bythe hot gases and the hot gases are scrubbed and substantially deterred. The partially distilled taris distilled to pitch which is withdrawn thi-u the coke trap 19 by the levelling arm 20. The position ofthe levelling arm controls the depth to which tar and pitch are allowed to accumulate within the still 10 and this in turn determines the nature of the spray thrown by the roll 17. The high melting point pitch produced in the-still may be drawn ot into the trough 21 and there suddenly chille'd and granulated by a stream of cold water from the line 22. 'Ihe pitch thus chilled may be col- 1 melting point' pitch collected in the bin 23, the

lected in any suitable storage vbin v23. y

When pitch of a high melting point, for example, pitch with a -melting point of 300 or 400 F. or higher is produced, the gases passing from' the still are enriched not only in lower boiling constituents but also in vapors .of higher boiling resinous or greasycompounds which are solid or semi-solid in an isolated state. Accordy ing to this invention these higher boiling constituents and oils substantially free from such constituents arey collected as separate products. The. hot enriched gases pass from the still 10 up thru the hot gas'saturator 11' where they are sprayed with tar; and the tar is partially distilled and,l the gases are further saturated in lower boiling constituents. The gases are then passed to the rectier-13. From the rectier the gases pass to condensers V25 land 26, which may be either direct orindrect condensers. The relativelyheavier oils separated in the condenser 25 are collected in the tank 27 and the lighter oils separated in the condenser 26 are collected in the storagetank 28.

Higher boiling oils from this storage tank 27 are returned in `whole or in part, depending on the nature of the tar distilled, the fractions desired, etc. to the Vrectifying column by the pump 29 thru the line 30. The condenser may be so located' asv to allow the oils to run bygravity to the rectifying column. 'I'he oils., are sprayed into the gases in the rectifier thru the spray nozzle 3l. Lower boiling constituentsof these oils are volatilized and carried over by the gases from the rectier into the `condenser 25. Resinous and greasy .constituents or other undesirable condensate of highboling range present in these higher boiling oils will to a large extent be separated out as* liquids in the rectifier 13. yThe unvolatilized oils together with any condensate formed from the vvapors in the gases flow down over the baliling means 32 in the rectifying column and are drawn off at 33. 'This high boiling fraction may be separately collected in the storage tank 34.

Instead of one condenser at 26, fractional condensersl may be employed. By proper control of the. amount, temperature and character of the oil returned to the rectifying column, the degrees of fractionation of the oil may be determined and the character of the oils drawn off from the rectifier, from the partial condenser and'from the total condenser or condensers may be regulated. L n In orderto produce creosote oil low inconstituents which are solid 'or semi-solid in an isolated state at ordinary temperatures, the operation is so vcontrolled that higher boiling resinous or greasy constituents are condensed from the gases in the rectifier 13. When all, the oils from the condenser 25 and tank 27 are reiluxed in the rectifying column, the oils condensed in the cooler 26 and collected in the storage tank 28 will be freeU or substantially free from higher boilingv solid or semi-solid constituents. This ,oil from the tank 28.may be used 105 alonev as creosote oil or where only a portion of the oilfrom the tank 27 has been refluxed thru the rectifying column, the oil from the tank 28 may be blendedwith a portion of the fraction condensed' in the cooler25 and collected in the tank 27 for creosote oil. Either oi1`may be blended with coal tar to produce so-called coall tar solution. J

The products of the operation are a high oil free lfrom higher boiling resinous or greasy constituents collected in 28, the fraction rich in these higher boiling constituents which is collected m34, and if desired, an intermediate oil from the tank 27. A portion of the oil from this tank 27 may be drawn off as a separate product or a portion .may be blended with the oil collected in the tank 28, they balance being' pumped to the rectifying column 13.

This apparatus shown in more or less detail in Figs. 1-3 is shown schematically in Fig. 4.

The coke oven battery is not shown in this -tlgurel The still is indicated at S. 'Ihe saturator 11? isy indicated lat T. The rectier 13 is shown at R. The condensersf25. and 26 are shownat C'l and C2. 'The pitch draw-oft and tar feed are indicated by the legends. This showing is schematic and Figs. 5-9 are similarly schematic and indicate various modifications of the apparatus hereshown. '135 Fig. 5 shows a slight modication ofthe arrangement shown in Fig. 4 in which the high boiling fraction separated in the rectifying column R is returned to the still together with the semi-pitch from the saturator T to subject it to redistillation.

Fig. 6 illustrates a still with tar fed to the still thru a saturator T and rectification. of oils with a single condenser C. Only a portionv of the oils recoveredn the condenser are sprayed s stead of being combined with the saturator T in a single column. The same processes can be carried out in the arrangement shown in Fig.v

Y to any desired use.

. Fig. 9 is still another modification of Fig. 4 in which the high boiling fraction from the rectifying columnR is blended with the pitch in the still to produce a composite pitch product. This high boiling fraction is returned to the still at -the end adjacent' to the pitch draw-off. High boiling constituents thus returned to the still may be subjected to partial redistillation, but to large extent they will be removed from the still blended withu the pitch before they are revolatilized. Instead of blending the high boiling fraction with the pitch in the still, the blending may be effected outside of the still after the pitch has been -drawn off from the still.

I claim: l 1. The method of distilling tar and recovering high boiling resinous or greasy constituents, which comprises bringing coal tar into direct .contact withhot coal gasification gases whereby the tar is distilled to pitch of a high melting -point and resinousA or greasy constituents are volatilizedfrom the tar, bringing the gases and vapors resulting from the distillation into direct contact with a regulated quantity of oil to eiect only partial cooling of the gases and vapors whereby resinous and greasy constituents are condensed and separated from the gases and remaining vapors, and subsequentlycooling the resulting gases and vapors to separate oils therefrom'. f

2.y The method of distilling tar and rectifying the distillate therefrom, which comprises bringing coal tar into direct contact with hot coal gasication gases, whereby the tar is distilled and pitch of a high melting point is produced, passing the resulting gases and vapors thru a rectify'- ing tower and then cooling thev resulting gases and vapors to lcondense oil and passing oil thus. 'recovered in a countercurrent direction and in direct contact with the gases and vapors passing -thru the rectifying column, whereby high boiling resinous and greasy constituents are condensed and separated from the gases and remaining vai pors in the rectifying column.

` 3. The method of distillingvtar andrectifyingV the distillate therefrom which comprises bringing coal tarvrinto directand intimate contact with hot gas in a still whereby the tar is distilled to pitch, passing 4,the resulting ygases and vaporsthru i 'a rectifying column and cooling them therein by bringing them into direct contactzwith oil conv densate of successively increasing volatility therein', returning condensate obtained in the rectifying column to the still, vand coolingthe v'gases and vapors leaving the rectifying column to -recover oil condensates.therefrom.`

, 4. The method of distilling tar andrectifying the distillate whereby oils, including oils of higher boiling range, substantially free from higher boiling resinous or greasy constituents are produced, which comprises bringing coaltar into direct contact with hot coal gasification gases,

l* whereby the taris` distilled and pitch :of a high to pass over from the rectifying column into the melting point is produced, passing the resulting gasesk and vapors thru a rectifying column and then thru a fractional condensing system where various oil fractions are separated from the gases and employing the highest boiling oil fraction as rectifying liquid in the rectifying column to sepf arate high boiling resinous or greasy constituents from the gases and remaining-vapors in the rectifying column while allowing higher boiling oils condensing system. Y

5. The method of distilling tar, which corn-4v I prises collecting the gases from a plurality of the ovens or retorts of the coal distillation plant, bringing them into direct contact with doaltar in a still, whereby the tar is distilled and pitch 1s produced, passing the resulting gases and vaporsthru a rectifying column, andthen thru a condensing system, bringing oil condensates into direct contact with the gases and vapors in the rectifying column in such a` manner as to cool the gases therein and subject'5the gases to con-v tact with condensates of successively increasing volatility to separate higher boiling constituents therein, and returning the higher boiling constituents to the still and blending ythem with the pitch therein. l v

6. The method of distilling tar, which comprises collecting the gases from a plurality of the ovens or retorts of the coal distillation plant, 105 bringing them into direct contact with coal -tar in a'still, whereby thel tar is distilled and pitch is produced, passing the resulting gases and vapors thru a rectifying column in a generally countercurrent direction and in direct contact with oil condensates so as to only partially cool the gases and separate higher boiling constituents therefrom, returning the higher boiling constituents to the still and subjecting them to redistillation therein, andcooling the rectied gases and vapors to recover the oil condensates therefrom.

7. The method of distilling tar and rectifying the distillate therefrom, which comprises bringing coal tar into direct contact with hot coal gasification gases, whereby the tar isdistilled and, pitch is produced' therefronnbringing the resulting gases and vapors into contact with further tar and distilling it, passing the resulting gasesv and vapors thru a rectifying column in a generally countercurrent direction to and in direct contact lwith oil condensates so as to only partially cool thel gases and separate higher boil'- ing constituents'therefrom, and thereafter cooling the rectied'gases and vapors to separate the tion gases, passing the semi-pitch and the hot gases thru a still-in a concurrent direction while spraying the semi-pitch into the gases in the form of a ne intense spray, whereby the semipitch is distilled to pitch of a high melting point, and` then bringing the resulting gases and vapors 4J into direct contact with tar and thereby distilling-the tar to produce the semi-pitch, passing thev resulting vgases Vand vapors thru a rectifying column in a generallyicountercurrent direction and in direct contactwith -oil condensates so as to only partially Ycool the gases and separate higher boiling constituents therefrom, and cooling the rectied gases and vapors to recover the oil condensates. y

9. The method of distilling tar and rectifying the distillate therefrom, which comprises bringing the tar into direct contact with hot coal distillation gases whereby the tar is distilled to pitch having a melting point of at least 300 F., passing the resulting gases and vapors up thru a rectifying column, withdrawing them from the rectifying columnand cooling them to recover oil condensates, spraying the oil condensates into the top of the rectifying column in such .a manner that the oil passes downwardly in the rectifying column in a generally countercurrent direction and in directl contact with the gases and vapors passing up therethru, thereby partly cooling the gases and separating high boiling greasy and resinous constituents therefrom, and withdrawing such constituents from the bottom of the rectifying colunm.

10. In combination with a coal distillation vplant a still, a hot gas saturator, a rectifying lplant, a still, a pitch draw-oir from the still, means for maintaining a small reservoir of liquid in the still, a roll for-spraying the liquid into gases passing thru the still, means for passing hot coal distillation gases from a plurality of the ovens or retorts of the coal dstillationplant into the still,

a hot-gas saturator, means for conveying tar to Lthe saturator and residue from the saturator to the still, arectifyi'ng column, a condensing system, means for passing hot gases and vapors from the still ;to the saturator and then to the rectifying column and then to the condensing system,v

simultaneously 'cleaned and then rectifyixg thev resulting clean gases to separate higher boiling oils from vapors of lower boiling oils said rectication being etected'by bringing oil condensate into direct contact with the gases and vapors in the rectifying column in such a manner as to coolthe gases therein and subject the gases to contact with condensate of successively increas- 'ing volatility.

13. The method of simultaneously producing high melting point pitch and creosote oil free from high boiling greasy and resinous constituents, which comprises distilling tar to pitch of high melting point by bringing the tarinto direct and intimate contact with hot coal gasification gases whereby high boiling greasy and resinous constituents are distilled off by the hot gases, removing the high boiling greasy and resinous constituents from the hot gases and vapors, and then cooling the remaining hot gases and vapors to 'condense a creosote oil substantially free from the high boiling greasy and resinous constituents.

STUART PARMELEE MILLER.

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