US1844901A - Distillation of tar - Google Patents

Description

Feb. 9, 1932. s. P. MILLER 1,844,901

DISTILLATION OF TAR ATTORNEYS Feb. 9, 1932. s. PjMlLLER DISTILLATION OF TAR Filed April 13. 1927 3 Sheets-Sheet 2 INVENTOB ATTORNEYS Feb. 9, 1932. P MlLLER 1,844,901

DISTILLATION OF TAR Filed April 13. 1927 5 Sheets-Sheet 3 INVENOR WMM ATTORNEYS Patented Feb. 9i 1932 UNITED srarrs PATENT orrics STUT PARMELEE KILLER, GIB'w TENAFLY, NEW JERSEY, ASSIGNO-R V1.0 THE BARRETT COMPANY, QF NEW YORK, N. Y., A CORPORATION F NEW JERSEY nIs'rILm'rroN or 'ran maintien inea Aprii is,

rlhis inventionvrelates tmimprovements in the distillation of tars, and particularly to the utilization of the heat available in the gases produced in coal-carbonization plants to distill tar and to produce oils and pitches by such distillation. The invention will be described especially with reference to its applieation'to coke ovens.

ln the ordinary operationof by-product I@ 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 the ovens of-the battery, The gases, commonly known as foul gases, leave the ovens at high temperature, e. g., 600 to 700 C. or higher, and carry a considerable proportion of volatilized tars and oils as well as entrained tarry matter and colte and coal dust. Ordinarily the gases 2o are cooled as rapidly as possible by the application of sprays of aininonia liquor or ammonia liquor and tar in the goose-necks and 'collector main, the heat in the gases being thereby dissipated and lost. The rapid cooling causes separation of tar containing heavier'oils in the collector main. Further cooling Ais effected in the cross-over main which connects the collector main. to the condensing system and in the condensing system, and an additional quantity of tar carry ing both heavier and. lighter oils is, thus separated. The collected tar is many cases is shipped from the coke-oven plant to a tar- 'distillation plant for distillation and separation of the oils and the production of pitches of varying qualities. Handling losses, freight charges and distillation. costs, including fuel and lcapital and maintenance eX- penses for the special equipment requiredvfor distillation, add to the cost of production of the tar-distillation roducts'.

lt is the object ofp the present invention to provide a method which permits the distillation of tar at a coke-oven plant, the utilization of the heat of the coke-oven gases for that purpose, and particularly the enrichment of the ases in oil vapors and the production of pitces having the various qualities and characteristics required by the trade.

According to the present invention the heat 1927. Serial No. 188,'263.

excess of the amount of heat required to distill all of the tar produced by the coke-oven battery. The present invention is designed particularly to utilize only a portion of this heat, that is to say, the heat carried by the so-called lean gases. These lean gases are withdrawn from the coke ovens during' the latter part of the coking operation, At this stage the amount of tar contained in the gases is relatively low and this tai' is relatively high in insoluble matter as compared with the tar contained in the gases given ed durinv' the early stages of the coking operation. ',llhere is no sharp line of division between rich and lean gases. Under ordinary conditions the gases leaving the ovens during the first half of the coking cycle may be regarded as rich,- that is, containing relatively lar amounts of .tarry matter. The ratio of ric to lean gas may, of course, bevaried widely to suit any particular set of conditions on distillation..

By utilizing these lean gases'to distill tar the gases are enriched in condensable oil vapors which may be recovered therefrom by suitable condensation. The lean gases, being relatively free from tarconstituents, are articularly desirable for the distillation an recovery of oils from tar or oils since upon condensation they yield such oils substan-` tially free from tar and suitable, therefore,

for immediate use for the various purposes for which such oils are adapted.

Good operation of by-product coke ovens requires that the temperatures throughout the block be maintained uniform. Therefore, coke-oven operators have devised systems of rotation for discharging and charging of the ovens which for any individual oven will affect the temperature of the block as little as possible. An example of the discharging.

and charging schedule is given below. It is assumed 'that the colte-oven battery consists of sixty ovens operating on a twenty-hour coking cycle per oven. Satisfactory tempera- Uff a ten-oven tures throughout the block may be maintained if the ovens are, as regards discharging and charging, divided into groups of ten ovens each. Int is then required thatwithin each ten-oven group the discharging and charging of the ovens be rotated in such a manner as to maintain uniformity of temperature within the group. Each oven is discharged and charged every twenty hours. Therefore, in

roup, an oven will be discharged 'and charged ever two hours.

The numbers elow illustrate a complete cycle for a group of ten ovens. The Roman numerals indicate the serial numbers ofthe individual ovens; the Arabic numerals indicate the order in which the individual ovens are discharged and charged, assuming for this example that No. I oven has just been discharged and charged.

I II# III 1V V VI VII VIII IX X Cycle 1-... 1 4 7 10 3 6 9 2 5 8 Cycle 2---- 11 14 I 17 m 13 16 19 12 15 18' It will beunderstood by those skilled in the art that the ovens in the first group of ten must be synchronized with those in the second group of ten, and so on, so that the temperatures throughout the entire batter are uniform. At the completion of one cyc e the number I oven has completed the distillation operation and is ready to be discharged and recharged with coal. Consequently in the group often ovens, certain of the ovens will be operating in the initial phase of the distillation operation; others will be in an intermediate stage and others will be approaching completion of the distillation. Assuming oven No. I to be freshly charged, the gases from ovens III, X, VII, IV and I will be rich, and those from ovens VIII, V, II, IX and VI will be lean. Two hours later, however, the ovens delivering rich gas will be V, VII, IV, I and VIII, and those delivering lean gases will be V, II, IX, VI and III. It will be evident to those skilled in the art that with this system of rotation of ovens, from the ten ovens in series 'at least two, and in some cases three or four of the ovens, will be delivering lean gas simultaneously.

If, therefore, only a limited amount of tar distillation is to be carried on as, for example, the distillation of the tar produced by the coke-oven battery, it may be suliicient to utilize only the lean gases from the first ten ovens of the battery at the appropriate time in the operation thereof. Thus, gases from at least two 'of the ovens of the first series can be employed for tar distillation, the gases from the selected ovens being directed at the appropriate time through suitable distillation apparatus in which the heat of these gases is utilized for the purpose of distillation. The gases from the remaining ovens of the series, being relatively rich in oil constituents during the initial stage of coal distillation, will be directed into the ordinary collector main and mingled with'gases from the remaining ovens of the battery.

Of course, where more distillation is to be effected the gases from a second series of ten ovens can be, utilized similarly and if desired all of the ovens of the battery can be so connected to the distillation apparatus as to deliver lean gases at the appropriate time thereto for the purpose of distilling tar, the ovens being connected at other times to the collector main in which the gases are cooled in the usual manner by the application of ammonia liquor or ammonia liquor and tar. Thus, tar from sources other than the battery can be distilled by utilizing the lean gases therefrom and such lean gases can be enriched in oil constituents which can be recovered subsequently by condensation.

In carrying out the invention the intimate contact between the hot lean gases and the tar to be distilled is accomplished preferably by spraying the tar into a suitable still in which the tar is subjected to the relatively high temperature of the gases for the purpose of vaporizing and separating the vaporizable oil constituents of the tar. The distillation can be conducted, for example, in an auxiliary collector main connected to the u take pipes through which the gases are with rawn from the ovens. Th e auxiliary collector main may be provided with spray nozzles for the introduction of the tar to be distilled in the form of a finely divided spray. The partially distilled tar or pitch resulting from contact of the tar with the hot lean gases can be withdrawn intermittently or continuously from the auxiliary collector main. It may be utilized after a single distillation operation as described or it may be recirculated through the auxiliary collector main for further distillation and separation of oil coustituents.

The 4invention can be applied without substantial change in the equipment and arrangement of an ordinary by-'product cokeoven battery. Thus, the gases produced in the earlier stages of the distillation in the respective ovens can be delivered to the ordinary collector main and subjected therein to cooling with ammonia liquor or ammonia liquor and tar to separate tar constituents from the gases. These gases may be conducted thereafter through the usual cross-over main wherein they may be further cooled and delivered thence to the ordinary condenser-s in which they are subjected, for example, to direct cooling with ammonia liquor for the purpose of separating tar and oil constituents. The t-ar and ammonia liquor withdrawn from the collector main, the cross-over main and condensers can be separated in suitable decanters and the ammonia liquor can be treated for the recovery of ammonia therefrom. and utilized for further cooling of the l hot coke-oven gases. The tar recovered may be distilled in the manner hereinbefore described to separate and recover vaporizable oil constituents and to produce pitches of thel tion. By operating the valves the lean gases produced in the latter stage of distillation will be diverted from the selected ovens in which coal distillation is nearing completion into the auxiliary collector main and while such lean gases are passing through the auxiliary collector main the latter will be supplied with tar to be distilled through the spray nozzles provided for that purpose. rlhe lean gases will thus heat and distill the tar and the oil vapors separated from the tar will be carried away with the lean gases which are thereby enriched in oil constituents. The partially distilled tar or pitch will 1 ilow into the bottom-of the auxiliary collectitl tor main and will be Withdrawn therefrom for use as pitch or it may be recirculated or otherwise subjected to further distillation tor the purpose of producing harder pitches and to recover additional quantities of oil vapors.

The distillation of tar in the auxiliary collector. main may be accomplished'in a variety ot ways involving the intimate contact'ot the tar with the gases therein. Preferably the introduction of ammonia liquor to the auxiliary collector main is avoided except as hereinafter described and in place thereof the main is flushed with a suiiicient 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 it a sutlicient quantity of the iiushing medium is provided and if the tempera ture is kept high because the heavy pitch if 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 flows through the main. All or a portion of. the tar can be introduced advantageously through spray nozzles provided for and in the connected goose-necks. In addi tion to the tar' or oil introduced through the spray nozzles in the collector main and Vgoose-necks, tar or oil 'or mixtures thereof can be circulated through the main by introducing it at one end thereo and with- A drawing it from the other. There are two important `requirements, the first of which is the intimate mingling of the tar with the lean gases from the ovens at high temperature to eiect the desired distillation and the other is the constant washing or lushing of the surfaces oit the main with a large excessof hot tar o r oil or mixtures thereof to prevent an accumulation thereon of heavy pitch. Both of these purposes can be accomplished by the use of spray nozzles. It

)can be accomplished likewise by the use within thev main of suitable mechanical agitating devices actuated to maintain a constant and violent' agitation -of the tar as it flows through the main so that the tar is splashed or thrown into the stream of cokeoven gases and onto the exposed surfaces yot the main.

The agitation can be effected bythe use of a rotating shaft or shafts with suitable paddles thereon. Similarly rotating cones or other agitating and s lashing devices may be disposed in the colector main and arranged to be actuated for the purpose of throwing the tar into the stream of gases and upon the exposed surfaces of the main. Discs, plates or spines on the rotating shafts will achieve the same purpose. The required agitation can be accomplished also 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 T., (McDaniel type ejectors) may be located in the main with their suction ends beneath the level of the tar therein. It the nozzles of the ejectors are allowed to extend above the surface of the tar a spray of tar will be thrown up into the gases. Y

Although indiscriminate cooling of the ases in the auxiliary collector main is to he avoided it may be desirable to introduce water or ammonia liquor with the tar which is sprayed into the auxiliary collector main to cool the gases to a predetermined and regulated extent. The regulation of the cooling eilect can be accomplished more readily with water because of the highest specific and latent heats of water as compared with tar and oils. It is possible, therefore, to add water or ammonia liquor in the proportion required to remove substantially all heat from the gases except that needed for the distillation of tar. 'When hard pitch is desiredless water can be added..

The gases and vapors from the auxiliary collector main are preferably delivered to a condensing system independent of the ordilos , ferent kinds.

na condensers in which the rich gases are coo ed. Such an independent condensing system may include condensers designed to separate all of the oil ,constituents to ether or fractional condensers may be emp oyed to remove the oil constituents from the gases in separate fractions having .different boiling points and adapted for various commercial uses. The oils recovered from the lean gases will be substantially free from tar constituents and adapt-ed, therefore for commercial use without further distillation or purification.

The amount of tar which can be distilled by the hot gases from a single coke oven is many times that which the coke oven itself produces so that the lean gases from relatively few selected ovens of the battery will suflice to distill all of the tar produced by the battery. It may be desirable, however, to

kutilize the heat from a greater number of ovens for the distillation of tar from other sources such as that produced by other coke ovens 0r from coal-distillation plants of dif- By connecting a suitable number of uptake pipes to the auxiliary collector main an additional quantity of tar from any source can be distilled effectively and the lean gases can be enriched in oil constituents which can be recovered subsequently for commercial use.

In carrying out the invention the tar may, as hereinbefore indicated, be brought into contact with the hot lean gases only once or it may be recirculated and again passedv through one of the auxiliary collector mains to effect a further distillation of the tar and the production of a harder pitch containing varying characteristics ,can be withdrawn; and utilized as commercial products or subjected to further distillation as may be desired. Y

The amount of distillation effected in the auxiliar;Y collector main can be regulated as desired by varying the quality of the tar introduced, the time during which' it is permitted to remain in contact with the hot cokebe described more particularly in connection with by-product coke ovens of the Somet- Solvay type.

In the accompanyin drawings, in which an apparatus suitable or the practice of the invention is disclosed,

Fig. 1 is a plan view of a portion of a cokeoven battery illustrating the application of the invention thereto;

Fig. 2 is a side elevation of the structure as illustrated in Fig. 1; and

Fig. 3 is an enlarged sectional view of the auxiliary collector main and connections.

Referring to the drawings, 5 indicatesra battery of ovens which are connected b uptake pipes 6 and goose-necks 7 to a col ector main 8. Thellatter may be provided with spray nozzles'in the usual manner for the introduction of ammonia liquor or ammonia liquor and tar,for the urpose of cooling the gases therein. The col ector main is connected to a cross-over main 9 which delivers the gases to condensers 10 wherein they are subjected to further cooling, for example, with ammonia liquor, for the purpose of condensing and separating the oil constituents. The gases may pass thence to an exhauster 11 which maintains the pressure balance in the system. Thereafter the gases may\be treated in the usual manner for the recovery of light oils and other valuable constituents, the gases being delivered finall to a suitable gasometer for storage as fue gases. The ammonia liquor and tar from the collector` main, cross-over main and condensers may be delivered to decanters 12 and 13 in which the tar is separated from the ammonia liquor. The latter may be treated in any suitable way to recover ammonia therefrom. The tar can be delivered to a tank 14 where it is stored for subsequent distillation in accordance with the invention.

A suitable number of the ovens, for example, the lirst ten, may be provided with separate uptake pipes 15 perferably at the rear of the ovens and communicating with a separate or auxiliary collector main 16 wherein the tar is distilled. The gases are permitted to pass from the ovens into the auxiliary collector main only during the latter part of the coal-distillation operation when the gases are relatively low in tar constituents. At the proper time, as indicated by the period of operation, the lean gases are diverted from the ordinary collector main into the auxiliary collector main and tar is supplied then through the spray nozzles 17 through pipes 18 from a source of supply such the tank 14, a pump 19 being provided to force the tar through the spray nozzles. The pitch can be withdrawn from the auxiliary collector main through a pipe 2O and all or a portion thereof can be rccirculated by means of a pump 2l through a pipe Q2 which is connected to the spray' :essaies or through a pipe 23 which delivers the pitch to the end of the collector main. Thus, the pitch may be subjected to further heating and distillation in the auxiliary .collector main to produce harder pitches and to remove more of the volatile constituents therefrom.

The lean gases carrying-the vaporizable oil constituents ofkthe tar pass through a pipe 24 into condensers 23 which, for example, may be arranged in series and may be designed to remove the vaporizable constituents in fractions so as to permit the recovery oi a number of oil products having diferent boiling points. The gases escaping from the condensers may be delivered through a pipe 24 to the exhauster 1l, being mingled with the gases from the remaining ovens of the battery and subjected to treatment for the recovery of light oils and other valuable constituents before the 'gases are finally discharged from the system.

The invention as described permits the dist-illation of tar in an economical and satisiactory manner to produce itches having the desired characteristics an to recover valuable oil constituents from the tar. The oils recovered, being `substantially free *from contaminating tar-constituents, may be employed directly Without further distillation or purification. The invention may be uti lized likewiseforthe distillation and purifica tion of dirty oils, that is to say,oils which are contaminated with tar constituents, such con-- stituents being separated and retained in the distillation apparatus. n

While l have described the preferred mode of operation according to the invention, it is to `be understood that various changes may be made in the procedure as described with- .,out departing from the invention or sacrificing any of the advantages thereof.l

1. The method of distilling coal tar and of producing pitch and distillate oils therefrom and from coal distillation gases, which com'- prises distilling coal, drawing o lean gases relatively low in tarry constituents given oi during the latter part of the coal distillation operation separately from rich gases given oli' during the earlier portion of the coal distillation operation, bringing the lean gases while still at a high temperature into direct and intimate contact-with the tar in regulated amount to eiiect distillation o? the tar and the production ot a pitch residue and of distillate oils which are carried in vapor form in the lean gases, and subjecting the admixed gases and vapors to cooling to condense oils therefrom.

2. The method of distillin coal tar and of producing pitch and distil ate oils ther from and from coal distillation gases, which comprises coking coal, drawing o lean gases given oil during the latter part of the colring operation separately from rich gases givenoff during the earlier portion of the coldng operation, distilling the tar by atomizing it into the lean gases after they are collected and while they are still at a high temperature.

ygases with the atomized tar, and cooling the resulting admixed gases and vapors to con-A dense oils therefrom.

3. The .method of distilling coal tar at coke oven plants and of producing pitch arid distillate oils therefrom and trom. hot coke oven gases, which comprises colring coal, drawing off lean gases relatively low in tarry constituents given ofi during the latter portion of the coking period separately from rich gases given oli during the earlier portion of the coking period and passing the lean gases while still hot through a still, atomizing tar to be distilled into the gases in the still and regulating the amount of tar brought into intimate contact with the gases with ref# erence to the high temperature oi the gases in the still so that the tar is rapidly distilled to produce pitch and distillate oils which are carried in vapor ici-mty the gases, drawing oli the resulting gases and vapors at a high temperature and cooling the same to conn dense oils therefrom.

In testimony vvhereoiE l az my si STUART PARMELEE ature. ER.

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