US1901872A - Method for treating tar and like oils - Google Patents

Description

March 2, E933. w HIGBURG ET AL l METHOD FOR TREATING TAR AND LIKE OIL Filed Jan. 12. 1926 2 Sheets-Sheet l mmm W. HIGBURG ET A1. LQLSZ METHOD FOR TREATING TAR AND LIKE OILS March 2, i933.

Patented Mar. 21, 1933 UNITED STATES PATENT OFFICE WILLIAM HIGBURG AND PETER C. REILLY, F INDIANAPOLIS, INDIANA; SAID HIGBURG ASSIGNOR '.lO SAID REILLY METHOD FOR TREATING TAR AND LIK-E OILS Application led January 12, 1926. Serial No. 80,792.

The present invention relates to physically and chemically alterin hydrocarbons, as will be more fully described herein.

An object of the invention is the provision of a process whereby any parain or straight chain hydrocarbon content (or what is termed sulphonation residue) of coal tar or coal tar distillates or hydrocarbon mixtures (if there be such sulphonation residue present therein) may be substantially or completely removed, a large portion thereof being transformed into cyclic and aromatic hydrocarbons (material capable of being sulphonated) and gases. We note however that the total amounts of as and of free carbon produced, correspon s to only a minor fraction of the total oil treated. The utility of such a process is evidenced by the fact that specifications for certain of the zo industrial applications of coal tar and coal tar distillates specifically inhibit the use of` a tar or oil that contains appreciable amounts of paraflinoid or straight chain hydrocarbons or sulphonation residue. Thus, in certain specifications for the use of tars and tar oils, the amount of sulphonation residue in the fraction distilling between BOO-360 C. is llimited to not more than one and one-half per cent. It therefore follows 3o that tar materials that have more than this amount of sulphonation residue are unfit for use under these specifications.

Irrespective of' any change in the sulphonation residue, the invention further relates to increasing the specific gravities and decreasing the volatility of hydrocarbon materials, tars and tar fractions, whether Aor not such materials contain a high or low (or in fact any) sulphonation residue.

The process and apparatus of the present invention effects the rectication of such tars or hydrocarbon oils which are largely of cyclic or aromatic nature, (if unfit for use under the above mentioned specifications) making them entirely applicable for preservative or other use under approved specifications. The invention will be rst described with reference thereto. The invention is also applicable to the conversion of unsulphonatable matter in water gas tar, such .tar being obtained in the destructive distillation of petroleum oil in the manufacture of gas, the unsulphonatable matter in such tar or tar distillate being reduced t0 a negligible quantity by the application of this invention. This constitutes a most' important application of the present process. Tars produced by lowtemperature carbonization of coal (which tars contain a relatively large percentage of straight chain au hydrocarbons) yield equally satisfactory products on conversion by this process.

The purpose of this phase of the present invention isto process, rectify, transform, or convert such tars, or tar distillates, or similar oils as contain paraflinoid h drocarbons or constituents that are not so uble vor reactable with hot concentrated sulphuric acid (i. e. herein termed unsulphonatable) into tars or oils that contain only traces or im- 7o material amounts of these materials; and at the same time to change the material treated in some other of its physical and chemical properties (especially as noted below); or the treatment of any tar or tar distillate or similar oil by this process to cause such desired changes in its` physical and chemical properties. This process as outlined herein will be hereinafter designated as the conversion process and the process reaction as the v fconversion reaction.

In this process a tar, pitch, tar distillate, creosote oil, dead oil, or other hydrocarbon oil consisting largely of cyclic hydrocarbons (or any desired fraction thereof) may be introduced directly as a liquid (but preferably as a vapor from a still or vaporizing device) into the treating or converting unit. The conversion unit consists of one or several tubes heated directly, or, preferably indirectly, to a suiiciently higll;

temperature to induce the reaction by w ch the parains or straight chain hydrocarbons or sulphonation residues are decomposed and converted into cyclic hydrocarbons and gases. At the same time other physical and chemical changes'are effected in the material treated,

Anal vertical section of the essential parts of the apparatus.

Figure 2 is a cross section on the line 2--2 of Figure 1.

Fig. 3 is a graph showing the relation between the temperature of treatment and speciic gravity of the oil.

Fig. 4 is a graphic table showing the proportion of tar acids in the converted and unconverted oil.

In said drawings 10 is a still for distilling a tar oil or the equivalent, isothermally, and carrying a layer of molten lead or equivalent 11, in its bottom.

An inlet pipe 12 foroil or tar is provided and is in communication with a constant and uniform feed box 13. 14 represents the outlet for distillation residue, i. e. part not vaporized, and 15 is a vapor outlet.

I'n the vapor outlet, weprovide a thermocouple T to indicate the temperature of the exit vapors. From this vapor outlet, the tube 16 conveys the vapors to the convert# ing element 17. This device preferably ta es the form of a cylindrical shell, having headers 18 and 19, formed by tube sheets 2O and 21 between which are connected a plurality of tubes 22, four of such bein shown in the drawings. One of these tu es contains the thermocouple 23 for indicating the existing temperature in the tubes.

From the space adjacent the outlet header 19, a tube 25 leads to a condenser, shown conventionally at 26, the condensate flowing into receiver 27, and the gas formed passing out through pipe 28 to a point of use, say to one or the other of the burners 29 and 30 employed for heating the shell 17 and the still 10.

Pipe 14 for the distillation residue may extend to a mixing chamber 30, which chamber is also connected with the receiver 27 by a ipe 3 1. The various pipes4 and outlets wi l, of course, be properly Valved as indicated in the drawings.

As a specific example of the process of the present invention the following is glven` without in any manner limiting the scope o the invention thereto. A coal tar oil of specific gravity 1.034 at 38 C. derived from the distillation of a vertical retort tar showed -a sulphonation residue in the fraction distilling between the limits 30G-360 C. of six and eight tenths per cent and was therefore a prohibited material for use as a preservative under specifications. This oil (before treatment) had a distillation range as follows:

This oil was vaporized or distilled isothermally in still 10, at a temperature of 350 C. and the vapors were passed directly from the still to the' conversion unit 17. The conversion unit consisted of several parallel tubes 22, one inch internal diameter, submerged in a bath of molten lead. The tubes and bath of molten lead were heated to a temperature of 700 C. (registered by thermocouple 23), for this run and this temperature was maintained during the process. As the vapors from the still passed through the tubes of the conversion unit and were subjected to the temperature there maintained, the conversion reaction proceeded rapidly. The progress and extent of this reaction was evidenced by the'elux of considerable quantitiesof fixed gases from thc condenser together with the condensed oil. The condensed oil when incorporated with the distillation residue over 350 C., that was drawn from the still through pipe 14, had the following properties:

Specific Gravity 1.069 at 38 C. Sulphonation Residue (300-360 C. fraction) 1.0%.

Distillation Per cent Up t0 210 C 2.1 Up to 235 C c 9.5 Up to 270 C 29.8 Up to 300 C 42.6 Up to 315 C 48.6 Up to 360 C 68.0 In this example, instead of usln a tar oil, we could introduce a tar into stil 10, but

lin such a case we would not necessarily mix the residue of the tar from still 10'with the condensate from tank 27, since such still residue would contain material which under certain specifications would be unsuitable for use as a constituent of a preservative oil.

By the process as detailed in the present case, we have in this example reduced thc paraiiin, straight chain hydrocarbonv content or sulphonation residue of this oil from six and eight tenths percent to one percent in the test fraction (3D0-360 C.). Based on the whole oil the sulphonation residue is reduced from seven and two tenths per cent to half of one percent. We have at the same time in this operation raised the specific gravity of the oil from 1.034 at 38 C. to 1.069 at 38 C., and have altered the oil in such manner that a somewhat greater proportion of the oil distills up to a temperature of 235 C., and a somewhat lesser proportion of the oil distills off up to a temperature of 360 C.; these distillates being determined by the approved distillation tests for the examination of creosote oil. We

5 have in this example converted a prohibited oil under commercial specifications into one that is entirely acceptable.

In the above example Aonly the vapors distilling off up to 350 C., were passed through the converting process for the reason that practically all of the material that it was desired to convert distilled ofi' below this temperature. In other cases it may be desirable to pass only the material distilling up to other temperatures (say 300 C. or 375 C.) through the conversion apparatus or it may be desirable to pass through only the vapors distilling through a certain temperature range. In other cases it may be de- 0 sirable to distill the oil ory tar to a coke and pass all or part' of the vapors of distillation through the conversion unit. Such variations in operation depend upon the characr ter of material to be treated and are so ineluded in the present invention.

Thus the temperature at which the' original oil or tar or fraction is distilled (or in other words the portion of the original which is vaporized) can be varied to suit the particular material under treatment, it being usually advisable to vaporize all or Vsubstantially all of the constituents which are not subject to sulphonation.

Directly heated tubes for the conversion of the vapors may be and have been used by us; ii: the practice of the present process. The advantage of using a lead bath in which the tubes for carrying out the ,reaction are submerged is twofold; first in that the lead bath to which the heat is supplied acts as a mobile distributor and equalizer of heat and prevents the otherwise unavoidable local superheating of the tubes when direct heat by gas or oil burners is supplied; secondly' 5 the lead bath holds 'Within itself a large supply of stored up heat that is continuously supplied to the converting tubes and the vapors to carry on the reactions of conversion and to efl'ectually neutralize any sudden and transient temperature fluctuations.

rIhe amount or degree of conversion obtained in the practice of the present process depends upon and may be controlled by varying the factors of rate of flow of the 5 vapors through the conversion tubes and by raising or lowering the temperatures of the conversion system and is so included in the present invention.

We call attention to the fact that the isothermal distillation or vaporization in the still 10, when under approximately atmos-v pheric pressure, is not a cracking operation, as no substantial amount of cracking occurs in this still. The conversion occurring in the tubes 22 is, in this instance, largely confined to open chain compounds, whereby these are converted into sulphonatable constituents, and only small percentages thereof are converted into gases.

The conversion reactions as herein described are preferably conducted and the Vproducts produced thereby are formed uning used), to fill these with a suitable filling material, in order to m'ore effectively bring all the vapors into direct contact with'the hot tube walls. Suitable filling for such purposes is well known and needs no de tailed description. Such iilling material may be catalytic in character, in order to cause the reactions to take place at a somewhat lower temperature, or to cause the reactions to be more complete. Examples of such catalytic material, are properly prepared iron, copper, alumina or nickel. It

will of course be understood that small tubes without fillings, are more easily kept clean.

In the above description, we have stressed the importance of the feature of the removal or conversion of sulphonation residue. Water gas tars are prevalent in the present industrial market and future practice in coal carbonization will, we believe, tend toward a continually increased production of low temperature tars. The distillates from these tars are in many cases (aside from sulphonation residue considerations) not acceptable to'the users of preservative oils because of their low specific gravities and because of their high volatility. Our conversion process will increase specific ,gravity and reduce volatility and so will make these unfit hydrocarbons suitable for use under present specifications.

Eample E.-We have taken a-pure coal tar distillate containing no sulphonation residue andhave treated it, by the method above described, at temperatures as shown Tempext'afmugt Gravity Yieid ment Per C' cent Increase in the gravity of the oil means a corresponding decrease in its volatility.

The graph constituting Figure 3 of the drawings, shows the same relation between the temperature of treatment (between 510 and 800 C.) and specific gravity on another and entirely different oil of which the orig inal gravity was 1.040. In a series of thermal treatments in which this oil was-processed at temperatures ranging from 510 to 700 C., a series of oils of gravities ranging from 1.040 to 1.084 were obtained as plotted in Fi re 3. .In another case a water gas tar distillate of gravity .97 at 38 C. was converted at 710 C. The converted oil had a gravity of 1.003 at 38 C. Distillation tests on the two oils showed a corresponding decrease in volatility.

E'ample 3.--Results obtained from low temperature tars show even more advantageous results on conversion. A low temperature tar distillate, being 90% of the total distillate from this tar, had a density of .994 at 38 C.' After conversion, as above described, at about 690 C., in our conversion apparatus the product produced from this oil had a gravity of 1.041 at 38 C.

Distillation tests showed a great decrease in the volatility of the oil. The properties of the converted and unconverted oils are shown in the following table:

Untreated Treated Gravity nt 38 C .094 1. 041 Sulphonation residue 8. 4% 1. 4% Tar Acids in -315 C. Fraction.. 42. 8 38. 7

Distillation:

Up to 170 C The decrease in tar acid content of thisV tuting Figure 4 of the annexed drawings show the large increase in the. amount of low boiling tark acids in the converted oil over that .present in the original oil. This :change in? tary acid content and in the constitution.' of the tar -acids themselves is dueto the conversionprocessing. There is a. muchlarger ,demand in thel market for acids of the'l'owboilingt'ype than for those of the higherboiling points which fact adds tothenvalue ofthe process. The low boiling point tar acids have a higher specific gravityor density than the high boiling point tar acids.

The graphic table constituting Figure 4 shows a comparisonl ofv the distillation ranges of purified tar acids obtained from the same vdistillate fractions of converted and untreatedoils.-

4With regard to apparatus used, we call attention to thejactthat the space 18, into which the vaporsare delivered, is relatively large, in order-,to allow the vapors to eX- pand.. into and fully mixinthis space. This allows equalization of pressure over space andcauses-equalvolumesxof the vapors, thoroughl mixed to travel through the several tu es,vandhto again thoroughly mix in the space 19.

While in thissp'ecification we have particularly shown .and described the conversion operation. as being performed on the material while .inalvapor phase, we call attention, to the ,fact that in-some cases the material may beintroduced into the high heating zoneas .liquids orvsprays or even as solids,.and.the claims of the present case are to be construed-asA covering such operaf tion, and also .,2,1i"e lintended to cover the carrying out Vinthe process at pressures below, equaito, or above, atmospheric pressure., l l Likewise'in,V the.'v claims, the expression a tube. does not indicate that one single tube is necessary'since several of such tubes may be employed if desired. Further, the broad process maybecarried out without the use of tubes in WhiclitQ'cOnduct the selective cracking operatio'nj- What is claimed is g 1. A procesls'foi"v -lowering the sulphonation residue of ,oily tar fractions'containing some unsulphonatable constituents, which comprises vaporiz,iiig the' desired volatile portion of the Asaine-and thereafterl superheating such vaporiz'ed portion suiciently to convert a large partof said unsulphonatable constituents into sulphonatable constituents andgases, condensing the vapors and mixing the condensate with ,the distillation residue ofthe first step.

2. A process ofi lowering the sulphonation residue of water gastar .distillates containling va substantialamountv ofsulphonation residue, whichcomprises-vaporizing a vvolatile portion of the same and thereafter superheating such vaporized portion suliiciently to convert a large part of said unsulphonatable constituents into sulphonatable constituents and gases, condensing the product thus produced and mixing the same with the distillation residue of the first step.

3. A process of lowering the sulphonation residue of tar distillates other than high temperature coal tar distillates, which comprises vaporizing a volatile portion of the same and thereafter superheating such vaporized portion sufficiently to convert a large part of said unsulphonated constituents into sulphonatable constituents and gases, condensing the product and mixing the same with the distillation residue of the first step.

4. A process of producing a creosote oil which comprises subjecting a hydrocarbon material of a predominantly tarry character, and containing not more than a few percent of constituents which will distil below 210 C., and containing an undesirably large sulphonation T'esidue, to a temperature above 510 C. and below 750 C. sufficient to selectively convert substantially all the unsulphonatable constituents thereof into sulphonatable materials, producing thereby a material of higher specific gravity and less volatility than the starting material.

5. A process of producing a creosote oil which comprises subjecting a hydrocarbon material of a predominantly tarry character, and containing not more than a few percent of constituents which will distil belowV 170 C., and containing an undesirably large sulphonation residue, while in the vaporized state, to a temperature of about 603 C. to 750 C., suicient to selectively convert substantially all the unsulphonatable constituents thereof into sulphonatable materials and gases, producing thereby a material of a higher specic gravity and of less volatility than the starting material. n

6. A process of making creosote oil which comprises subjecting a hydrocarbon material consisting largely of cyclic and aromatic substances of which only a small percentage will distil below 170 C., but containing sulphonation residue in excess of 1.5% to a. temperature of about 510 C. to 7 50 sufiicient to selectively convert substantially all the unsulphonatable constituents thereof into sulphonatable materials.

7. A process of treating tars and tar oils containing substantially over 1.5% of sulphonation residue in the BOO-360 C. fraction, and containing a substantial amount of high-boiling low density tar acids to produce a creosote oil containing tar acids of higher density, which comprises vaporizing the major part of the high-boiling low density tar acids along with the tars and tar oils, passing such vapors through a heated

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