US1892654A - Method and apparatus for distilling tar - Google Patents

Description

9 1932- s. P. MILLER METHOD AND APPARATUS FOR DISTILLING' TAR Filed Jan. 16, 1929 3 Sheets-Sheet 1 INVENTOR ATTORNEYS bank/um; 76%

Sheet 2 3 Sheets- S- P. MILLER METHOD AND APPARATUS FOR DISTILLING TAR Filed Jan. 16, 1929 Dec. 27, 1932.

Q -M MW Dec. 27, 1932. s. P. MILLER METHOD AND APPARATUS FOR DISTILLING TAR Filed Jan. 16 1929 3 Sheets-Sheet 5 ATTORNEYS Patented 27, 1932 UNITED STATES PATENT OFFICE STUART PABHELEE MILLER, 01' ENGLEWOOD, NEW

xarnon AND 'Arrm'rus Ion ms'ritn'me The.

Application filed January 18, 1929. Serial No. 332,779.

Accordin to the present invention, tar is 1 duced therefrom by direct contact of the tar and pitch with highly heated gases, such as those from coke ovens, gas retorts, etc; and the hot enriched gases leaving the still are passed through an indirect heat interchanger and condenser for cooling and condensing oils and for preheating tar; and the tar is preheated in this way to a temperature such that part of the light oils are removed therefrom and a low melting point pitch is produced. The thus preheated and partly distilled tar is then supplied to the stillfor further distillation. The present invention is tion of coal tar at coke oven plants or at coal gas plants by using the highly heated coke oven or coal distillation gases for effecting the distillation.

When tar is distilled by direct contact with highly heated'gases, such as coke oven gases, the distillate oils are carried as vapors admixed with the gases leaving the still, and these oils are recovered by subsequent cooling of the admixed gases and vapors to effect condensation of the vapors. In order to accomplish such. condensation, 'it is necessary distilled an high melting point pitch pro-- particularly advantageous for the distilla-' ly heated gases, and in which the highly heated enriched gases from the still are employed for preheating and partly distilling the tar to remove light oils therefrom, and in which p the thus preheated and partly distilled tar is then supplied to the still. The lighter oils which are removed by the preliminary preheating and artial distillation can be readily condense because they are free from admixed inert gases. The preheating of the tar by indirect contact with the hot enriched gases from the still serves to cool the gases and condense oils therefrom, thus recovering valuable waste heat and employing it for the preheating and fpartial distillation of the tar.

Theremoval 0 the light oils from the tar before it enters the still greatly reduces the loss of light oils with the gases, and greatly improves the condensing operation for condensing the oils from the inert gases. The condensers can be operated at a higher temperature, and the higher boiling oils can be more readily condensed from the gases. The preheated tar thus enters the still in a preheated condition where its heat is taken advantage of in increasing the unit distillation capacity of the hot gases in the still.

The present invention is particularly advanta'geous for distilling tar withfuel gases 8 such as coke oven or gas retort gases, producer gas, water gas, etc. These fuel gases are produced at a high temperature and contain a large amount of waste heat which is commonly dissipated and lost. Such highly heated gases are produced, for example, at tempera tures around 550 to 800 C. or higher. They are at such a high temperature that if tar or pitch were brought into contact therewith in limited amounts and with local overheating, the tar or pitch would be rapidly coked. However, by subjecting such gases to thorough and intense spraying with tar or pitch,

and by regulating the supply of tar or pitch,

the tar or pitch can be rapidly distilled at the same time that the gases are almost instantly. cooled to a temperature approaching that to which the tar and pitch are heated. In producing high melting point pitch, the

gases leave the still highly enriched with oil we tillat-ion before it enters the still proper.

' gases.

vapors and at a high temperature. For example, in distilling tar with hot coke oven gases to produce pitch of around 400 F. melting point, the hot enriched gases may leave the still at a temperature around 250 to 400 C., the hot coke oven gases entering the still at a much higher temperature, for example, around 550 to'800 C.

The hot enriched gases from such distillation contain a large amount of heat, partly in the form of sensible heat of the gases and vapors and partly in the form of latent heat of the vapors. ccording to the present invention these highly heated gases and vapors are utilized for the preheating and partial distillation of tarbefore the tar is supplied to the still, and the distillate produced by the preliminary preheating and partial distillation is taken off and separately condensed so that only the residue from the preheating and initial distillation enters the still. The preheated and partly distilled tar may enter the still itself or may enter the vapor chamber through which the hot enriched gases leave the still and be there subjected to further diIsn such case, the further distillation will remove additional oils from the tar, but these will be higher boiling oils. These additional. oils distilled from the tar by direct contact with the hot gases and vapors will mix with the gases and vapors and be recovered therefrom on subsequent cooling and condensation.

The apparatus of the present invention comprises a still connected with a suitable source of highly heated fuel gases, such as those from coke ovens, etc., and having means for bringing the tar and pitch in the still into thorough and intense contact by spraying with the gases passing through the still. The high melting pointpitch produced can be drawn oft, and the gases and vapors will leave the still as highly heated enriched An indirect condenser is provided for cooling these hot enriched gases and condensing oils therefrom, and this condenser is arranged as a preheater for preheating tar to a temperature to effect partial distillation of it. A separate condenser is provided for the preheated and partly distilled tar, and only the residue from which the distillate has been removed is supplied to the still for further distillation.

In addition to preheating and partly distilling tar before supplying it to the still, part of the preheated and partly distilled tar can be drawn off as lOW, melting point pitch, and only the remainder of the low melting point pitch supplied in a preheated state to the still. In this way it is possible to produce simultaneously a high melting point pitch from the still, and a limited amount of low melting point pitch from the preheating operation. This separate withdrawal of part of the pitch will reduce the amount of pitch supplied to the still, and if the amount so supplied is not sutiicient, additional tar, or tar preheated and partly distilled in some other way, can be supplied to the still. In general, however, the process will be so carried out that the preheated tar, from which part of the oil has been removed by the preheating operation, is supplied to the still as the feed of tar or partially distilled tar (pitch), and only such surplus of low melting point pitch will be withdrawn as may be desired for use as a separate low melting point pitch product.

The partial distillation of the tar in the preheater can be supplemented by applying vacuum to the preheater, thus giving an increased percentage of oil distilled from the tar, and a pitch of somewhat higher melting point. The extent to which the distillation is carried in the preheating operation can be regulated to a greater or less extent by regulatingthe operation of the still and the temperature at which the gases leave it. and the rate at which tar is passed through the preheater. B arranging a generally countercurrent flow ot the tar and of the hot gases, the tar can be preheated to a temperature somewhat lower than that of the hot gases leaving the still, and the gases can themselves be cooled to a temperature somewhat higher than that of the cold tar entering the preheater, thus accomplishing more or less free condensation of oils from the hot enriched gases, and preheating of the tar to a temperature such that a considerable percentage of oils will be distilled therefrom.

The indirect condenser and preheater can advantageously be a pipe coil through which the tar is pumped under pressure and around which the hot enriched gases pass in indirect heat interchanging relation with the tar in the pipe coil, and from which it discharges into avapor box. The tar can be pumped through the pipe coil continuously and under pressure and preferably in a generally countercurrent relation to the hot gases and thereby heated to a high temperature such that when the tar is discharged into the vapor box, a considerable percentage of the tar will be separated in the form of vapors, and a hot 1 J itch of low or medium melting point directy produced. If the vapor box is maintained under a vacuum, the amount of distillate can be considerably increased, and the melting point of the pitch increased, although the temperature of the pitch will be reduced by the further distillation under vacuum.

The invention will be further described in connection with the accompanying drawings, which show in a conventional and diagrammatic manner arrangement of apparatus at a coke oven plant embodying the invention and adapted for the practice of the process of the invention, but it is intended and will be understood that the invention is 1 I indicated at 12 so that the gases enter the.

illustrated thereby but is not limited thereto.

Fig. 1 shows a plan view of a coke oven battery equipped for carrying out this invention;

Fig. 2 is an elevation, partly'in section, of the tar distilling means shown in Fig. 1;

Fig. 3 is a cross-section on the line 3-3 of Fig. 2; I

Fig. 4 is a cross-section onthe line 4-4 of Fi 2; and

ig. 5 shows a slightly modifiedtype of apparatus in elevation.

In the drawings, a coke oven battery 5 is shown equipped with uptake pipes 6, a collector main 7,center box 8, and cross-over main 9 which may be of the usual type and are shown schematically'in Fig. 1. At the rear of the coke oven battery of Fig. 1 are additional uptake pipes 10 connected with the hot gas header 11. By manipulation of valves in the uptake pipes 10 connected with the hot gas header and the uptake pipes 6 connecting the same ovens to the usual collector mai'n 7, the gases from these selected ovens may be directed either to the collector ma n or to the hot gas header.

The hot gas header is heavily insulated as still 13 at only a slightly lower temperature than that at which they leave the ovens. .The still is equipped with means for producing an intense spray of tarv or partially distilled tar in the gases, so that the'tar will be distilled by the hot gases and the hot gases in turn will be detarred by the tar spray. The means shownfor producing this s ray comprises the roll 14 which is locate near. the

curved wall of the still 15. It is so positioned ed with the motor 16- and whenrapidly rotated, e. g. at 900-1200 B. P. M. the roll throws an intense s ray of the tar or partially distilled tar rom the bottom of the still up into the hot gases passing through the still. The gases enriched in" vapors distilled from, the tar and almost entirely free from tar fog, leave the still through thetower 17.

The hot enriched gases which may leave the still at a temperature anywhere from 250? C. to 400 C. when medium hard or very hard pitch is being made pass up through thetower 17 and then through the main 18 V into theheatinterchanger 19 where the hot gases are brought into'indirect contact with the tar which is admitted at 20 and passed upthrough the heat interchanger through thecoil 21 in indirect contact with the hot gases and is heated thereby. The gases are The tar which is heated in the heat inter- I changer and which may leave theheat interchanger at a temperature somewhat lower than the temperature of the gases which enter through t e main18, is conducted through thepipe 23 into the vapor box 24: where vapors of low boiling constituents distilled 7 from the tar separate fromthe undistilled residue and pass from the vapor box through the vapor main 25 to thecondenser 26 which ma be of the direct or indirect t ype. The

lig t oil distillate from thiscondenser 26 is drawn oil" into thereceiver 27.

The partially distilled tar or low melting point pitch which is left after the distillation is drawn off from the vapor box through the draw-off 28 and may advantageously while still atelevated temperature be fed to the still 13. h

The preheated pitch or partially distilled tar from which the low boiling vapors have been removed and collected inthe condenser or pitch vaporized in the tower will passover with the hot enriched gases through the main 18 to theheat interchanger 19. The spray within the settling chamber, which is located preferably between the two sets ofbaflles 30 and 31, helps to wash from the gases any entrained articles of pitch which may be carried overrom the still by the hot gases. The non volatilized material which collects in the bottom of the tower is preferwhich. the hot gases enter the still and is, therefore, advantageously collected in the bottom of the tower and fed to the still through thepipe 32. By bringing the partially distilled tar orlow melting point pitch from the'settling tower into direct contact with the hottest gases and passing the hot gases and the material to be distilled through the still in .the same direction, the finished pitch which is preferablyof high melting point is sprayed into gases of reduced temperature which are partially saturated with oil vapors and the tendency to coke the high melting point pitch spray is not so great as though the tar and gases flowed countercnrrent to one another.

Where the material withdrawn from thevapor box 24 is to be distilled to a point where the greater proportion of the lighter boiling constituents have been removed and is therefore required to be preheated to a relatively high temperature, a higher degree of preheat will result from feeding the residue from the vapor box directly to the still and preferably at a point in the vicinity of where thepipe 32 enters the still.

The pitch fromthe still which is preferably a high melting point pitch and may be a pitch with a melting point as high as 400 F. 1s withdrawn from the still through thetrap 33 by means of theadjustable arm 34 and is collected in thetrough 35 where it is sprayed with water from 36 and chilled. The chilled ,pitch and water are collected in thetank 37 and the pitch may be put to any desired use. A pitch of melting point lower than 400 F. may be made e. g. pitch of 180 F. to 200 F. melting oint; in such a case the partially or lightly istilled tar from the vapor box may be a less distilled tar than if the hi her melting oint final pitch were made. euch itch will preferably not be cooled in water at may be collected in cooling bays or in. tanks in which it mav be held liquid for subsequent use if desired.

The extent to which the tar is preheated within theheat interchanger 19 and consequently the amount of vapor released in the vapor ox may be varied. The production of a pitch oflowermeltingpointmaybeobtained from thevapor box 24 or a pitch of higher melting point, relatively, may be obtained. Lower boiling constituents are separated from the tar in this vapor box, and since they are not diluted with inert gases, as are the vapors present in the condenser connected with the still 13, these vapors of low boiling constituents may be readily condensed and a high yield of low boiling oils will be obtained directly. lVhere the quantity of residue drawn off from the vapor box through the draw-ofi' 28 is greater than that which it is desired to add to the still, a portion of thisresidue throufghthe pipe 38 into thereceiver 39 and.

may be separately withdrawn used or any purpose.

\Vhere the hot enriched ases have been subjected only to partial cod ling in theheat interchanger 19, these gases are drawn off into further condensing means 40 which is here shown as a direct condenser in which the gases are sprayed with water or ammonia liquor through thesprays 41. The liquids collecting in the bottom of thecondenser 40 are withdrawn to thedecanter 42 from which ammonia liquor is separated into thetank 43 and clean oils of relatively low boiling range are collected intank 44, although it is to be observed that due to the fact that oils of low boiling range have been removed from the tar in the vapor box the quantity of low boiling oils which can be recovered from the enriched gases is less than would otherwise be expected. From the condenser the gases pass to theexhauster 45 and thence to means for the recovery of ammonia and li ht oils which may be of the usual type. here it is desired to remove from 24 such a quantity of tar may be introduced through partially distilled tar as to leave insuflicient for feeding the still 13, or where the amount of tar added at 20 is to be limited, additional tar may be added at 32' or through theline feeding spray 29.

An alternative arrangement is shown in elevation in Fig. 5. The hot gas header 11 and still 13 are of the same general structure as that shown in the preceding drawing, and the settlingchamber 17 may be of the same structure, although in Fig. 5 the preheated tar is shown as entering the still at 50 instead of entering the still through thetower 17. The still 13, the header 11, the settlingchamber 17, main 18 andheat interchanger 19 are all heavily insulated. The finished itch from the still is withdrawn throught e trap 33 and the hot enriched gases leave thetower 17 through the main 18 and are cooled in theheat interchanger 19. Tar from 20 is assed through the heat interchanger referab y in a direction countercurrent to t e fiow of the gases and passes in a preheated condition through theinsulated pipe 23 to theinsulated vapor box 51.

I Fig. 5 shows preheating means 19 from whic the preheated tar is discharged into a.vapor box 51 which ismai ntainedunderavacuum. From the vapor box the vapors pass to acondenser 52 which is also maintained under vacuum. Avacuum pump 53 is shown at 23. It is connected with thecondenser 52. The clean low boiling oils condensed from the vapors which are separated from undies" tilled residue in the vapor box and email, because of the vacuum, may comprise oils of higher boiling range than would ordinarily be produced in the vapor box, are withdrawn through theseparator 53 and thebarometric column 55 and collected in the clean oil storage. 56.

The undistilled residue from the vapor box is withdrawn through a similarbarometric column 57 and collects in thereceiver 58. Residue from this receiver is pum ed in preheated condition by the pump 59 t rough the insulated line 60 into the still 13 at 50. A

portion of the undistilled residue may be.

withdrawn through theline 61 into the low melting itch storage tank 62 and be employed tb'r any desired purpose. Where withdrawal of the greater proportion of such partially distilled tar is desired, additional I for production of hard pitch in still 13. I

The gases leaving theheat interchanger 19 through the main 63 may contain some oil vapors carried over from the still by the gases through the main 18 which are not condensed in theheat interchanger 19. This will be true when the condensation is so regulated as to collect only the heavier oils in theclean oil storage 22. Since the tar is top (1 in thevacuum vapor box 51 before being admitted to the still 13, the content of vapors Cir of low boiling oils in the enriched gases will be low. Any oils leaving theheat interchanger 19 through themin 63 may be condensed in further cooling apparatus for recovery of uncondensed oil and the gases will then be treated-as usual for the recovery of ammonia and the usual light oils.

I claim: 7

1. The m'ethod of distilling coal tar by direct contact with highly heated. coke oven gases, which comprises distilling pitch by sprayin it into the gases in a still with such t orougliness and intensity that the gases are rapidly cooled to a temperature approximatin that to which the resulting pitch is heate regulating the operation as to produce a high melting point pitch and hot enriched gases leaving the still, passing the hot enriched gases in indirect contact with the coal tar to preheat the tar, regniating the rate of supply of the tar to the-prehcater so as to preheat it to a temperature suiiicient to P efiect partial distillation thereof, separating the resulting vapors of lower boiling point oils from the preheated and partially distilled tar residue, withdrawing the distillate from such partial distillation, and supplying the tar residue to the still in the form of low melting point pitch to be there further distilled to produce high melting point pitch, whereby the distillate" produced in the still by direct contact with the hot coke oven gases is a distillate relatively free from low boiling point oils, which can be readily condensed from admixture with the gases on cooling. "1

2. The method of distilling coal tar by di rect contact with highly heated fuel gases,

which comprises bringing such gases into direels and intimate contact with a spray of pitch in a still wherebythe pitch is distilled and regulating the intensity of the spray and the operation of the still to produce high melting point pitch and hot enriched gases leaving the still, passing the hot enriched gases into direct contact with preheated and partly distilled tar to eil'ect further distillation thereof, passing the resulting hot enriched gases into indirect heat interchanging relation with the coal tar to he preheated.

and distilled and thereby cooling the enriched gases and condensing oils therefrom, regu lating the supply of tar to the indirect preheater so that it will be preheated to a temperature that will effect partial distillation of oils therefrom, separating the resulting oil vapors from the preheated and partially distilled tar residue. separately withdrawing and condensing the oils so distilled, passing .the tar residue into direct contact with the hot enriched gases leaving the still and thereby effecting further distillation of oils therefrom and further preheating of the residue, and supplying the resulting' preheated and partly distilled residue tothe stillfor further distillation therein.

3. The method of distilling coal tar and of simultaneously producing high melting I,

point pitch and low melting point pitch which comprises subjecting preheated and,

partially distilled tar (pitch) to distillation by direct contact with highly heated fuel gases in a still and regulating such distillation to produce high melting point pitch and hot enriched gases, passing the hot enriched gases into indirect contact with the coal tar to be preheated, thereby cooling the gases and condensing oils therefrom, and preheating the tar, regulating the supply of tar to the preheater so that it will be heated to a tempera ture sufiicient to distill part of the oils therefrom, withdrawing the preheated tar into a vapor separating chamber and separately condensing the resulting distillate, withdrawing low melting pitch residue remaining from such preheating and distillation, and supplyin part of such low melting point itch residue to the still to be there further distilled to produce high melting point pitch.

4. The method of distilling coal tar by direct contact with highly heated coal distillation ases which comprises distilling tar or pitch y brin ing tar or pitch in a still into thorough an intimate contact with the gases in a still under such regulated conditipns that a high melting point pitch residue is produced and highly enriched hot gases leave-thestill, passing the hot enriched gases condensing the oils so distilled, and supplying at least part of the preheated and partly distilled tar to the still.

'5. An apparatus for distilling tar, comprising a still provided with means for introducing highly heated gases therein and for spraying pitch into the gases to effect its distillation so that high melting point pitch can be produced and hot enriched gases leave the still, a heat interchanger and indirect condenser, means for passing the hot enriched gases from the still to the interchanger and condenser to effect cooling thereof and condensation of oils therefrom, means for supplying tar to be preheated to the interchanger and condenser to effect its preheat ing and partial distillation, means for withdrawing and separately condensing the distillate so produced, and means for supplying the partly distilled tar, freed from such distillate, to the still to be there further distilled to produce high melting point pitch.

6. An apparatus for the distillation of tar,

comprising astillprovided with means for be there further distilled to produce high introducing fuel gas thereto in a highly heatmelting point pitch.

ed state and with means for bringing pitch into intimate contact with the ases in the still, means for withdrawing high melting point pitch from the still, means for withdrawing hot enriched gases from the still and for passing them into indirect heat exchange relation wlth tar to be preheated and partly distilled, means for drawing ofi the condensate from such indirect preheater, means for supplying tar in a regulated way to said preheater, means for drawing off and separately condensing the distillate produced by such preliminary distillation, means for introducing preheated residue from such preliminary distillation into direct contact with the hot enriched gases leaving the still to effect further preheating and distillation thereof, and means for introducing the resulting preheated and partially distilled residue into the still to be there further distilled.

7. An apparatus for distilling tar, comprising a still having means for introducing highly heated fuel gases thereto and for withdrawing hot enriched gases therefrom, means for bringing pitch in said still into intimate and thorough contact with the gases passing therethrough whereby high melting point pitch can be produced and hot enriched gases leaving the still, a heat interchanger and indirect condenser and tar preheater having pipe coils. therein over which the hot enriched gases pass to effect preheating thereof and cooling of the gases and condensation of oils therefrom, means for supplying tar to said pipe coils to preheat it by indirect Contact with the hot enriched gases, a Vapor box into which said pipe coils discharge, a separate condenser arranged to condense the vapors removed in said vapor box, and means for introducing the preheated residue from said preheatiiifiand partial distilling operation into the still for further distillation.

8. An apparatus for distilling tar comprising a still provided with means for introducing highly heated gases therein and for spraying pitch into the gases to effect its distillation so that high melting point pitch can be produced and hot enriched gases leave the still, a heat interchanger and indirect condenser, means for passing the hot enriched gases from the still to the interchanger and condenser to effect cooling thereof, and condensation of oils therefrom, means for supplying tar to be preheated to the interchanger and condenser, means for withdrawing the preheated tar therefrom, and a vacuum pump with means for subjecting the preheated tar to reduced pressure, means for withdrawing and separately condensing the distillate produced under reduced pressure, and means for supplying the partly distilled tar free from such distlllate to the still to In ture.

testimony whereof I afinr my i .STUART PARMELEE MILLER. 19

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