US1844741A - Distillation of tar and rectification of the distillate therefrom - Google Patents

Description

DISTILLATION 0F TAR AND RECTIFIGATION oF THE DISTILLATE THEREFROM Feb. 9,5 1932. w.\ M. BYWATER Filed Aug. 31, 1929 5 Sheets-Sheet l f M@ Q ATTORN EYS HE DISTILLATE THEREFROM 1929 5 Sheets-Sheet `2 Feb 9, 1932 wx. M. BYWATER DISTILLATION oF TAR ANDREGTIFICATIQN oF T Fied Aug. 51,

ATTORN EYS FMD. 99 1932. w, M, BYWATER M lw DISTILLATION 0F TAR AND RECTIFICATION OF THE DISTILLATE THEREFROM Fild Aug. 31, 1929 3 Sheets-Sheet Cv ENVENTOR 40%# 3M BY ATTORNEYS lll lilatented Feb. Q, 1932 WLLFRED M. BYWTER, 0F WEEHAWKEN, 'NEW JERSEY, ASSIGNOR TO THE BARRETT COMPANY, 0F NEW YRX, N'. Y., .A CDRPMTIGN 0F NEW JERSEY lDlSUlILLATION 0F TAB, AND RECTIFICATION 0F THE BISTILLATE THEREFRM y Application tiled August 31, i929. Serial ,'lo. 389,678.

lhis invention. relates to the distillation of tar by direct Contact with hot gases, and rectiication of the distillate therefrom. lt includes both the new method and'apparatus.

According to this invention, tar is distilled by direct contact with hot gases, the gases and vapors resulting from the distillation oi the tar are passed thru a rectilying column and then thru an indirect condenser where they are partially cooled to separate oils from the gases and these oils are returned `to the rectifying column and cause the separation of higher boiling constituents from the gases in the re cti'fying column. The gases and vapors leaving lthe indirect condenser are cooled to recover one or more oils of lower boiling range which are free or substantially free from higher boiling constituents of the range which are separated from the gases in the rectiying column. v

rlhe temperature of the gases and vapors passingthru the indirect condenser is controlled to cause condensation and separation of higher boiling oils, only. These oils in passing down the rectifying column in contact with the upflowing distillation gases cause condensation of the highest boiling .constituents carried hy the gas. The lower `looling components of the oils flowing down the rectilying column are yolatilized and again Ipass with the gases into the indirect condenser, `The separation of the distillate into a higher boiling 'traction and one or more lower boiling fractions is such that the constituents in the higher boiling traction are free', or' substantially so, 'from oils of the lower boiling range, and the oils of lower boiling range are free, or substantially so, from constituents of the higher boiling range.

The distillation of tar by hot gases contemplated hy this invention is such as to yield ya gas enriched with a suflicie'nt per cent ot' oil vapors to lend itself to rectification and the fractional recovery of condensable constituents. The gases entering the rectifying column of this invention contain at least seven percent byvoluzne of condensable constituents,nnd preferably ten or fiften percent by volume or more, and are in substantial equilibrium with the enriching medium.

n The hot gases employed for the distillation of the tar are preferably hot coal distillation gases or other hot coal gasification gases lli hen hot coke oven gases or other 'line intense spray which not only exposes a large surface of the tar to the action of the hot gases whereby the tar is distilled, but the line intense spray of the tar and pitch simultaneously scrubs and detars the gases, removing entrained tarry `and pitchy particles so that on subsequent cooling of the gases the oils which separate will be clean oils substantially free from tarry or pitchy constituents.

`When cokey oven gases are employed for the distillation of the tar, they are advantageously employed at substantially the teinperature at which they leave the ovens and while they contain substantially their original vapor content, When pitch of high melting polnt, e. g. 300 F. or 400 E, is to be produced, the temperature of the gases employed 'for the distillation is such that 'the gases, even after partial cooling as a result-oi the distillation are of such a temperature that they will carry from the still in the vapor state constituents lof higher boiling range including compounds which are solid or semisolid in an isolated state at ordinary-ternperatures. Such higher boiling compounds include not only the constituents distilled from the tar but also compounds of this boiling range present in the gases as they leave the ovens. The process of this invention may be employed to advantage to separately recover such ,higher boiling constituents from lower boiling oils in order to obtain a high yield of oils which are free, or

`substantially so, from such higher boiling constituents; The higher boiling compounds thus separated from the gases may be collected as a separate product, or they may be blended with the pitch produced-'or they may he employed in any other way, as desired.

Where a high melting point pitch is to be produced, it is desirable to pass the hot gases and the tar to he distilled through the still in a concurrent direction while spraying the tar into the gases so that the hot gases entering the still are sprayed with incoming tar which may be partially distilled before it enters the still, and the pitch which is produced after continued spraying of the tar into the hot gases will be sprayed into gases which have been cooled and enriched to some extent by the distillation and production of pitch in them. These conditions tend to prevent overdistillation of the tar or pitch and the formation of coke in the still. In pro ducing pitch of high melting point, the tar may advantageously be distilled in two stages. In the second stage, semi-pitch from the first stage is brought into direct contact with the hottest gases and distilled to pitch ,of high melting point. In the first stage tar is distilled to semi-pitch by direct contact with the hot gases and vapors from the second stage. Y' The gases which have been employed for distillation of higher boiling constituents inY the second stage ot the distillation are then employed for distillation of lower boiling ingredients from the incoming tar, and thus their vapor content is increased. The method of distillation and the type of still which may be employed, according to this invention, are not thus limited, however, since various types of stills and various methods of distillation may be employed.

The cooling medium employed in the indirect partial condenser following the rectifying column according to this invention maybe water or tar or any other desired Huid. Tar may advantageouslybe employed as the cooling medium and the tar thus heated may be `fed to the still or it may be sprayed into the gas saturator where one is employed. Heat economy is thus effected and the eapaeity ot the apparatus for distillation is increased.

The invention will be further-described in connection with the accompanying drawings, in which it is applied to the distillation of tar in hot coal distillation gases, and the rectifying of the resulting vapors. It is intended and is to be understood, however, that the invention is not limited thereto.

In the drawings,

Fig. 1 is a plan view of one applicationof the invention;

Fig. 2 is an elevation of the apparatus shown in Fig. l.;

Fig. 3 is a cross-section thru the still of Fig. 2; and

Fig. 4 is an elevation ot a modified form ot apparatus.

In the drawings, 5 is a coke oven battery. The individual ovens of' the battery are connected thru the uptake pipes and goose necks G with a `collector main 7. From the collector main the gases pass thru the cross-over main 8 to rondcnsers and meansl tor the recovery of ammonia, etc. (not shown). rl`his apparatus may be of the usualtype and is shown more or less diagrammatically in the drawings.

At the opposite side of the coke oven battery is a still 10. Selected ovens of the battery are connected thru the uptake pipes and goose necks'll and the hot gas header 12 with this still 10. By the proper manipulation of valves in the uptake pipes and goose necks 6 and uptake pipes and goose necks 11, the gases from lthese selected ovens may be passed either thru collector main 7 to the usual by-product recovery system or thru the uptake pipes 11 and the hot gas header 12 into the still 10. The gases enter the still at approximately the temperature at which they left the ovens and with substantially their original vapor content. In the still is al roll 13 which is adapted to be driven at high speed by the motor 14. This roll when rotated a speed of 900-1200 R. P. M. for example, sprays the tar or pitch up into the hot gases passing thru the still and exposes a large surface of the tar to the distilling action of the gases and simultaneously scrubs and detars the gases, removing any entrained tarry and pitchy constituents present in the gases. The pitch produced is withdrawn from the still thru the tray 15 and the levelling arm 16. Means suited to the recovery of pitch of the melting point produced, is provided. The drawings show a trough 15 with a cold water spray 16 for granulating pitch ot high melting point. By varying the position of the levelling arml 16, the depth of tar or pitch maintained within the still can be controlled, and this in turn controls the na-v ture of the tar spray produced in the still. The tar is fed to the still thru the line 17 and passes thru the still in a directionconcurrent with the fiow of the gases thru thestill. The roll is advantageously set at one side ot the still, as shown more clearly in Fig. 3.

The hot gases and vapors leaving the still pass up thru the tower 20. This tower comprises several compartments. The bottom compartment 21, is a hot gas saturator or saturating chamber in which the gases and va- `down thru the gas passage 27 back into the still. Any particles of tar spray thrown from the roll and carried by the gases into the tower will be washed out ot the gases by thetar spray in this bottom section 2l ot the tower.

` Vaporspassing to the condensers at a constant 'llhe gases leaving the compartment 2l pass up thru the rectitying tower 30. This tower is advantageously tilled with batliin'g means 3l, such as Raschigmings or other suitable means for exposing a large surface of oil to the action of the hot gases and vapors which pass up thru the rectit'yingtower.

|The gases and vapors leaving the rectifying column pass to the indirect condenser 35, where partial cooling is ellected, and higher boiling oils are separated from the gases and these oils are returned and retluxed 'thru the rectifying column. Through partial cooling by indirect contact in the condensers 35 and refluxing in the rectifying column Q1 of the oils which separate in this condenser', substantially complete separation of the higher boiling constituents 'from the lower boiling constituents is obtained.

A cooling medium such as water or tar is passed thru the partial'condenser 35. This cooling medium enters at 36 and is drawn off at 37. The amount of cooling medium passed thru this partial condenser is so controlled desired temperature, and thus to condense and separate from the gases higher boiling oils which it is desired to reflux thru the rectifyinp` tower in order to produce the desired tractio;=ation. The high boiling fraction which collects in 'the bottom of the rectifying tower is drawn oft thru the line '39 and may be separately collected in the tank 40.

or may be used as desired. For example, all or part of this 'fraction may be returned tothe system for redistillation, e. g., to the saturator 2l-,or the still l0.

The hot gases and the vapors which pass thru the indirect condenser 35 are conducted thru the main to the condenser 46. This condenser may be of any suitable type. A direct condenser in which the gases are sprayed with water from the line 4T is here shown. One total oil o r several oil fractions may be'collected in this condensing system. The oils and any non-volatilized cooling medium which collect in the bottom of the condenser are drawn `oifinto one or more decanters 48. and the oils are separately collected in the storage tank or tanks 49. Tanks are provided 'for collecting ammonia liquor from the decanters. An exhauster 5l is provided for drawing the gases and vapors thru the system. Means for the recovery of ammonia and light oils. etc. are located lieyond this exliaustein The saturating chamber 2l. `therectifying column 30 and the partial condenser 35 are here shown as being located one on top. of another in a column.vk This arrangement' is not essential to the invention. The saturator may be omitted, the gases and vapor;-f may leave the still, or the satnrator'where one is employed, thru a' mainand pass thence to the rectifying tower which may be situated. Where desired. Although the partial condenser 35 need not be located directly over lthe rectifying tower and oils condensed and separated from the gases by contact with the cooling coils in the partial condenser may be pumped and sprayed into the rectifying tower 30, the partial condenser' is advantage ously situated directly over the rectifying tower so that oils which separate from the gases in the condenser pass by gravity into the reeti'tying tower.

The uptake pipes l1, the hot gas header 12, the still l0, the spray chamber 2l and the rec tifying tower 30, are advantageously heavily insulated, as indicated at 52, to prevent loss of heat by radiation.

The boiling range of the traction drawn off thru the line 39 into the tank /lO is controlledby the amount and temperature of the gases passing thru the still and the saturator, the amount of tar sprayed into the gases thru the nozzle 23, the nature ot the tar distilled and the melting point of they pitch produced, etc., as well as by the amount of cooling medium passed thru the partial condenser 35.

Fig. 4 shows a coke oven battery 5a, the selectedk ovens of which are connected thru the uptake pipes and goose necks lla thru the hot gas header 12a with the still 10a. This still 10a` may advantageously be situated at -the oppositeside of the` coke oven battery ovens with the regular collector main, the

gases from the desired number of ovens may be passed thru the hot gasv header 12a into the still 10a. YThe still lha is equipped with a spray roll 13a and a pitch draw-ott" lha similar to those described in connection with. the preceding figures. The operation of the still may be as described in connection with those figures. ,From the still the hot gases llO andtvapors pass up thru the tower 60. This tower comprises three compartments, the sat uratorl, thelrectifying column 62 and the partial condenser and tar preheater G3. From the partial condenser the hot gases and vapors pass thru the 'main 64 to any suitable type ot condenser.

Tar is fed thru theline V65 to the partial condenser 63 which is an `indirect condenser or heat interchanger in which the gases and/- vapors are cooled and 1n which tarentermgat 65 is simultaneously preheated. This preheated tar drawn oli the condenser thru the line 66 is sprayed into the gases in the saturator-Gl thrii the nozzle 67. Additional tar may be added to the line 66 thru the line 68. Battles 69 are provided to insureexposing a large surface of the preheated tar to the action of the hot gases. The tar is partially disbaffling means.

tilled in the saturating chamber and the distillation residue, which may be a low melting point pi-tch, is drawn olf from the bottom of the tower thru the line'70. A part of this distillation residue may if desired be separately collected in the tank 7l as a low melting point pitch product. The remainder` or all of the partially distilled tar is fed into the still 10a thru the line 72. The tar entering at 72 has been partially distilled in the saturator 6l by direct contact with the hot gases and vapors leaving the still and at least a part of the tar has been preheated in the indirect condenser 63. 1

The gases and vapors leaving the saturator 6l pass up thru the rectifying column 62 and are partially cooled in the heat interchanger 63. Oils which are condensed and separate from the gases pass down thru the rectifying column over the baffling means 74. The large surface of contact between the oil and hot gases and vapors in the rectifying tower provides rectification and sharp fractionation of Jhe oils so that the heavy oil condensate, which collects in the bottom of the rectifying column 62 and isdrawn off thru the line 75 into the storage tank 7 6, is an oil of relatively high boiling range, and represen ts the highest boiling oil fraction collected from the system. Its character will. depend upon the character of the tar distilled, the degree of fractionation employed, the melting point of the pitch made, etc. v

The amount of gases passing` thru the still, the nature-of the tar distilled in the still, the melting point of the pitch produced, etc. control the temperature of the gases and vapors entering the saturator thru the passage 78. The amount to which thesegases and vapors are cooled in the saturatoris controlled by the temperature and amount of'tar sprayed thru the nozzle 67 and the ecieney of the By controlling the fraction of low melting point pitch which is separately collected in the storage tank 71, the saturator and still mav be operated as different units to produce pitches of different desired melting points. Similarly, by controlling the amount of tar passed thru the partial condenser 63 and where possible, controlling the temperature of the tar passed thru this condenser, the cooling effected in the condenser and consequently the amount of oils'condensed and refluxed thru the rectifier isQControlled; this step may be made independent of the distillation which is effected in the saturator 61 and in the tar still 10a by passing any desired proportion of the tar thru the heat interchanger 63 and/adding the balance to the system thru the line 68. The tar supplied thru G8 may he tar of the sam'ekind and temperature as that suppliedy thru the line or tar of a different kind or different temperature maybe-employed. i The control of the tar thru these two lines is regulated by the valves 79 and 80.

VAlthough the invention is more particularly described herein as applied to the distillation of tar by hot coke oven gases, it is not limited thereto and may be applied to advantage to tar d istillations employing the heat of other waste gases, for example, hot gas retort'gases, hot water gas, hot producer gas, etc. l/Vhere hotcoal gasification ases are employed, they are used at substantially the temperature at which they leave the ovens or retorts and while they contain substantially their normal vapor content, i. e. before the removal of an appreciable amount of tar or pitch therefrom. Because o the intensive tar spray to which they are' subjected, and because of the thorough flush- Iing of the walls of the still as provided in the apparatus shown, apparatus of this type may be employed for distilling tar with gases of a temperature sufliciently high to cause coking of the pitch formed if this Spraying and flushing were not provided. Vhen gases of such a `high temperature are used the tar and gases are advantageously passed thru the still in a concurrent direction so that the fresh tar is sprayedinto the hot gases and the partially distilled tar is sprayed into gases which have already been somewhat cooled and which are partially saturated with vapors from the previous use of the gases for distillation of the incoming air.

I claim: y 1. The method of distill'ing tar from a coal distillation or gasification plant and rectifying the distillate therefrom, which comprises bringing the tar into direct contact with hot y gases to effect distillation thereof and to produce pitch, passing the resulting gases and vapors thru a rectifying column and rectify ing them therein, and then thru an indirect condenser where they are partially cooled by indirect heat exchange with a suitable cooling medium, thereby separating condensable constituents from the gases, bringing this condensate into direct contact with' the gases passing thru the rectifying column, and then cooling the gases leaving the indirect condenser to separate lower boiling oils therefrom. y

2. The method of distilling'tar from a coal distillation or gasification plant, which comprises spraying tar into hot coal distillation gases at a temperature at which they retain substantially their original va or content, thereby, distilling the tar an producing pitch, and simultaneously scrubbing entrained impurities from the hot gases, pass. ing the resulting gases and vapors thru a rectifying column and rectifying them therein and then thru an indirect condenser and cooling the gases therein to produce a condensate, preheating the tar b v indirect heat exchange with the gases and vapors inI this condenser,

to pitch, means for passing hot coal distillation gases from the plant in to the still, a rectifying column, an indirect condenser and a further condensing system with means for passing the gases and vapors from the still therethru in succession and means for re turning condensate from the indirect condenser to the rectifying column.

9. In combination with a coal distillation 10 plant, apparatus for the vdistillation of tar and the rectification of distillate therefrom, comprising a still for the distillation of tar to pitch, means for passing hot coal distillation ases from the plant into the still, a recti ying column, an lindirect condenser and a further condensing system with means for passing the gases and'vaporsfr'om the still therethru in succession, means for returning condensate from the indirect condenser to the rectifying column, and means for passing tar thru the jacket of the indirect condenser and from there to the still.

10. In combination with a coal distillation plant, apparatus for the distillation lof tar and the rectification of distillate therefromcomprising a still for the distillation of tar or semi-pitch to itch, a pitch draw-off, means for passing ot coal distillation gases from the plant to the still, means for spraying tar into direct contact with the gases and vapors leaving the still, a vrectifying column, an indirect condenser for effecting partial cooling of the vaporsy leaving the rectifying column, means for'supplying oil removed from the gases in the indirect condenser to the rectifying column, and further condensing means beyond the indirect condenser. i Y

1l. In combination with a battery of coke 40 ovens, a still, insulated means` for 'passing hot coal .distillation gases from the ovens into the still, a pitch draw-off from the still, spray means in the still to spray semi-pitch up into the hot coal distillation gases in the form of an intense spray, whereby the semipitch'will be distilled and the gases will be substantially detarred, a hot gas saturator, a gas connection between the still and the hotgas` saturator, a tar spray in the saturator, and means for feeding semi-pitch roduced in the saturator to the still, a rectiigying column thru which the gases and va ors pass from the saturator, an indirect conV enserior cooling the gases and va ors leaving'thevrectif ing column, means or bringing tar into in irect contact with the gases and vapors 1n the indirect condenser, whereby the tar is, heated, means for supplying the heated tar to the saturator, and further condensing means located beyond the indirect condenser. In testimony whereof I atlix signature.

WILFRED M.,B s ATER.

CERTIFICATE 0F connection Patent No, Latem, a cramedreemiy 9, 1932i, m

WILFRED M, BYWATER,

It is' hereby Vcertified that error appears in the printed specification of the above numbered patent requiring correction as foliows: Page i, line 73, for the -ietter "E' read; page 2, line 94, for "tray" read trap, and line 115, for the misspelled word "vaports" read vapors; page 4,- lne 98, for "air" read tar; page 5, lines 54- and 84, claims 5 and 6, respectiveiy, after the comma insert the words and reotifying them therein; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office, Y f

Signed anni sealed this 22nd day of March, A.. D, i932o M., i., Moore, (Seat) Acting Commissioner ot Patents,

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