US1826428A - Pitch composition and method for making the same - Google Patents

Description

Oct, 6, 1931. s. P. MILLER I 1,326,428

PITCH COIPOS ITIQN AND METHOD FOR MAKING THE SAME I Filed June 17, 1927 2 SheetsSheet 1 ELEcne/ou. mum/mum T? 1 'co/w E/yJHu 19 E ii Fir Z7 7 7:4? 29 l 25 I i (q/05min 7 5 l4 22 3 5 Z7 27 H 3 36 W 11 F Q z= 7 5i 7 Fl/EL I 4 INVENTOR 9? r v fig r7fl ew 2 4 ATTORNEYS Oct. 6, 1931.- s. p. MILLER 1,826,428 O PITCH COMPOSITION AND METHOD FOR MAKING THE SAME Filed June 17, 1927 2 Sheets-Sheet 2 Fi -43, i .4.

/8 7 /7 /7 :''.;i 7/41 f: 246 7 :Hi /6 /9 TE 5 u I ATTORNEYS Patented Oct. 6, 1931 UNITED STATES PATENT OFFICE STUART P. MELEB, OF TENAILY, NEW JERSEY, ASSIGNOB TO THE BARRETT COMPANY,

. OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY PITCH G OHPOSITION AND METHOD FOR MAKING THE SAME Application filed June 17, 1927. Serial No. 198,451.

The present invention relates to an improved method of producing pitch composiions.

The pitch composition is a composite prodnot made by blending coal tar with pitch directly recovered from coal distillation gases, the blending being carried out to produce a substantially homogeneous product. The new composition is of value for fuel purposes, for example, as a fuel in open hearth steel furnaces; it is also of value for other purposes, such as for road building and treating pur oses, etc.

e improved method of the invention includes the treatment of hot coal distillation gases, and particularly of coke oven gases, while at a high temperature by an electrical precipitator to separate therefrom the suspended solid and liquid as constituents in the form of a directly recovered pitch, and the blending of the resulting pitch while still hot and thinly fluid and preferably in asubstantially continuous manner, with coaltar to form a substantially homogeneous product. The separation of the pitch directly from the cove oven gases at a high temperature leaves in the gases a lar e amount of oil vapors which are subsequently recovered by cooling the cleaned gases to produce clean or substantially clean oils.

For carrying out the process an electrical precipitator is provided in the by-product system of a coke oven plant for treating the hot coke oven gases at a high temperature to separate pitch therefrom, and means is provided for blending or mixing the resulting pitch, while still hot and thinly fluid, and in a substantially continuous manner, with tar to form the new composite product. The apparatus also includes a condensing system for recovering from the gases and vapors cleaned by the electrical preci itator, clean or substantially clean oil con ensates, etc.

Ordinary coal tar pitch is produced by the distillation of coal tar in externally heated batch typeor continuous tar stills. This distillation, when carried to a sufliciently high temperature to remove the oils which it is desirable to remove by such distillation, and to 5 give a-pitch residue of relatively high melting point, is accompanied by a very considerable decomposition of oil constituents of the tar with the result that the amount of pitch produced is considerably greater than that originally contained in the tar before distillation and with corresponding decrease in the yield of oils produced by the distillation. The formation of pitch during the distillation is accompanied by the formation of carbon and the pitch so produced may contain a high carbon content largely produced by the de structive distillation to which the pitch is subjected during the process of removing oils therefrom. The production of pitch in this way involves first the production of tar from the coke oven gases and the subsequent heating of this tar to distill it to remove oils therefrom and to give the pitch residue which contains the constituents not volatilized at the temperature at which the distillation is carried out and the decomposition products produced during such distillation.

The present invention eliminates the need for distilling tar for the reduction of pitch and makes use of a pitc of different composition and properties which is directly recovered from the coke oven gases and which is free from the products of decomposition produced during the production of ordinar pitch by distillation in externally heate stills. The oil content of the directly recovered pitch is also different from that of pitch produced by distillation of coal tar in the customary manner, even where the two pitches have the same melting oint. The production of the pitch employe in the new composition is also combined with the production directly from the hot coal distillation gases of clean oils which can be employed without subjecting them further to distillation, for example, as creosote oils, or for the extraction of tar acids therefrom, etc. The production of such oils, as well as of the pitch, is efiected without the necessity of d1s-' tillation of tar in the usual manner to produce distillate oils and a pitch residue.

As applied to a by-product col e oven, the present invention involves applying an electrical precipitator where it can treat the hot coke oven gases at a sufficiently high temper- (iii ature to separate pitch therefrom while leaving oils, including high boiling oils, in the form of vapor to be' subsequently recovered by cooling of the cleaned gases. The coke oven gases leave the coke oven at a high temperature, for example, around 700 C. or higher. The gases from the different ovens are commonly collected in a collector main common to a number of ovens and the gases pass from the collector main through a crossover main to the condensing system. Usually the gases in the collector main are cooled by ammonia liquor, or by ammonia liquor and tar, to a relatively low temperature so that the gases reach the condensing system around 75 to 90 C. The tar is separated to a considerable extent in the collector main, usually as a heavy tar, while tarry oils are separated .in the condensers. The heavy tar and tarry oils are commonly mixed together and distilled to give coal tar distillates and pitch residue.

According to the present invention. I avoid the excessive cooling of the hot coke oven gases prior to the time they pass to the electrical precipitator. The precipitator may advantageously be arranged at or near the place where the gases leave the collector main and pass to the cross-over main and the temperature of the gases passing through the collector main is kept sufliciently high to permit the direct recovery of pitch therefrom in the electrical precipitator and the passing of the oils, including high boiling oils. in the vapor form through the cross-over main to the condensers. In order to avoid deposition of hard pitch in the collector main, it may advantageously be kept flushed with hot liquid pitch circulated therethrough. So also, tar may advantageously be introduced .into the collector main in the form of sprav and also as a current of tar flowing through the lower part of the collector main with resulting distillation of the tar and the production of pitch therefrom and of distillate oils which pass over in admixture with the hot coke oven gases to the electrical precipitator and thence to the condensing system. A high temperature of the gases leaving the collector main may also be obtained by using a limited amount of ammonia liquor spray in the collector main or by merely flushing the main with ammonia liquor. or a mixture of ammonia liquor and tar. or a large amount of wet tar. Ammonia liquor in limited amounts may locally cool some of the gases to a much lower temperature but the average temperature of the gases leaving the collector main may nevertheless be sufilciently high to carry most of the oils. including a large amount of heavy oils boiling e. g.'above 350 C. over in the vapor form from the collector main through the precipitator.

The temperature at which the electrical precipitator is operated, that is, at which the hot coke oven gases pass through the precipitator, can be varied, and the hardness of the pitch produced can be varied. For example, by passing the gases through the electrical precipitator at a temperature around 150, C. a somewhat softer pitch will be produced than when the temperature is around 200 C. or 250 C. or higher. At any of these temperatures, the electrical precipitator will remove from thehot coke oven gases those constituents which are in a suspended state while the oils which are in the form of vapor at such temperature will pass on with the gases to the condensing system. By regulating the temperature of the electrical precipitator and of the gases passing therethrough, there will be separated with the pitch more or less of the heavier oils, the amount being less as the temperature ofthe gases treated is increased. In general, it is desirable to clean the gases with the electrical precipitator, and to separate pitch therefrom. at a sufficiently high temperature so that a high yield of creosote oils can be obtained from the gases on subsequent cooling, and so that these creosote oils will contain a considerable amount of higher boiling oils, including constituents boiling above 350 C. and including constituents which are incapable of distillation by ordinary distillation methods without decomposition.

The pitch residue or product produced by the electrical precipitation treatment of the hot coke oven gases will be produced continuously and at a high temperature at which it will be thinly fluid. According to the present invention, this pitch is employed while still in a hot and thinly fluid state by blending or admixing it with tar in a continuous manner to form a homogeneous fuel product.

The blending or mixing of the directly recovered pitch with the tar is advantageously efiected bv causing the pitch and the tar to flow together continuously in streams which blend with each other. Ordinary "coal tar contains small and varying amounts of water.

The directly produced pitch is at a temperature' far above the boiling point of water. However. by blending the hot pitch andthe relatively cold tar in the form of a continuous stream and by providing for the escape of such vapors as may be formed bv the intermixture, this intermixture takes place to form a substantially homogeneous product. The high temperature of the pitch and its intimate contact with the tar during the, admixing operation results in heating the tar or the resulting mixture and in removal from the tar of part or all of its water content, while more or less of the lower boiling point oil constituents of'the tar may likewise be removed.

Depending upon the proportions in which the tar and pitch are admixed. the resulting mixture will have a higher or lower temperature,

but the mixture will be sufiiciently homogene- The proportions in which the pitch and cipitator to throw me ting point pitch I operated at high temperatures to give a comtar are admixed can be varied. In some cases,

.for example, equal parts of the directly recovered pitch and of the'tar can be admixed to give the composite fuel product. In other cases, a larger amount of tar can be employed, for example, using up to three or four parts or more of the raw tar to one part of the directly recovered pitch, depending upon the melting point of the pitch and the character of the tar employed. Instead of using composite tar, resulting from admixtureof the heavytar from a collector main and the tarry oil from condensers, the heavy tar-from the collector main, or from the collector main of another, coke oven battery operated at a lower temperature in the usual way. can in some cases be advantageously employed for admixture with the directly recovered pitch, leaving the 't'arry oils available for use for other purposes.- Furthermore, the admixed pitch and tar can be subsequently admixed with additional tar where this is desired.

The heavy tar thrown down from the gases in the collector main may vary considerably with the temperature at which the collector main is operated and with variations in the condition of operation, e. g. depending on whether ammonia liquor is employed for cooling in the collector main, or ammonia liquor and tar, or only hot tar or pitch. Even where hot tar is circulated through the collector main and sprayed into the gases therein the tar or' pitch from the center box of the collector main will usually have a lower melting point than the pitch thrown down in theprecipitator due to the local overcooling of part of the gases before they leave the collector main This is also true where ammonia liquor is employed in the collector main where it will cause local overcooling and the throwing down of tar from gases which may have an average temperature sufficiently high when they leave the collector main and pass through the predowu relatively high melting point pitches in the precipitator. The heavy tar thrown down in the collector main may be blended in suitable proportions with the hot pitch from the precipitator, after the tar has first'been separated from ammonia liquor, in case ammonia liquor is employed inthe collector main.

When an electrical precipitator is operated at a much lower temperature, e. g. around to 100 (3., it will throw down a tar which will be free or relatively free from lower boiling oils that pass through the precipitator in the vapor'state at such temperature.

Tar so thrown down from cooler gases can be em loyed for blending with the hot high from the precipitator substantially homogeneous mixture,

posite product. In this case the product will be made up of the high melting point pitch blended with the soft pitch or heavy tar in proportions to form a composition suitable for use for various purposes.

The new composition of the present in-' vention,- made of directly recovered pitch and of tar or soft pitch blended to form a is valuable for use for various purposes. It is characterized by a low carbon content and by substantial absence of decomposition products produced in ordinary pitch during the destructive distillation to which it is subjected when produced in ordinary externally heated tar stills.

The new composition is valuable for use as fuel and the new method for making it is valuable in that it enables the fuel to be produced continuously at a coke oven plant while simultaneously producing clean oils valuable for creosoting and other purposes, or producing composite products made of the clean oils and of tarry oils suitable for use for creosoting purposes which can thus be directly produced simultaneously with the production of pitch composition. Roadtreating compositions which are soft pitches having a melting point, e. g. around 105 F. can advantageously be made in accordance with the present invention. while simultaneously therewith there may also be produced at the coke oven plant creosoting composition made up either of cleaned oils or of blended clean oils and tarry oils.

The invention will be further described in connection with the accompanying rawings, illustrating certain forms of apparatus adapted for the practice of the invention; but it will be understood that the invention is illustrated by but is not limited to the specific embodiments described.

In the accompanying drawings,

Fig. 1 shows in a conventional and diagrammatic manner, part of a by-product recovery system of acoke oven plant modified to include provision for the direct recovery of pitch from the hot coke oven gases and for the continuous blending or admixture of this pitch with raw tar;

Fig. 2 is a sectional view of a modified form of electrical precipitator combining therein provision for admixing and blending the directly recovered pitch with raw tar, and

Figs. 3, 4 and 5 are respectively an elevation partly in section, a transverse section, and a plan view partly in section, of the precipitator illustrated in Fig. 1, the specific construction of the precipitator being that of the McCloskey Patent No. 1,752,920, issued April 1, 1930.

In the apparatus illustrated in Fig. -1, a coke oven is shown conventionally at I, having the usual uptake pipes 2 leading to a collector main 3 common to a number of ovens,

usually twenty ovens of a battery. The gases from the collector main pass through the main or pipe 4 to an electrical prec1p1- tator indicated at 5, in which the gases are treated at a high temperature to separate pitch therefrom.

The itch which is continuously separated from t e gases in the electrical precipitator and which is hot and thinly fluid, flows continuously through the line 20 to a mixing chamber 25, into which raw tar is also continuously introduced in regulated amounts through the line 26. The pitch and tar enter the chamber 25 near one end and collect in the bottom thereof and flow to the other end, during which flow admixture takes place while the raw tar is heated by the hot pitch and more or less distillation of water and light oils will take place therefrom. The lended mixture flows out continuously through the line 27 into a tank or receptacle 28 which may be the storage tank or receptacle or from which the mixture may be pumped or supplied to the fuel burners or to a storage or supply tank therefor.

The mixing receptacle 25 serves the purpose not only of a mixing compartment in which the flowing streams of raw tar and hot pitch are blended and admixed but also serves the purpose of a vapor releaser for collectin water vapors and oil vapors which may %e driven off from the tar. These vapors escape through the pipe 29 and are cooled in the condenser 30 and the condensate collected in the trap 31 from which it may either be refluxed back into the mixing compartment 25 through the line 32 or from which it may be permitted to escape with any covery system (not shown).

permanent gases through the line 33. apors may also be allowed to escape through line 29' gas in line 34.

The hot coke oven gases after the separation of the pitch therefrom in the electrical precipitator pass through the cross-over main 34 to the condensers indicated conventionally at 35 in which the hot gases are cooled, or the cooling is completed, to give either a comosite condensate or a series of condensates ractionally condensed and which may be kept separate from each other. The gases after such condensation then pass to the ammonla recovery system and to a light oil re- The oil or oil fractions separated from the cleaned gases in the condensing system will be clean or substantially clean oils. Such oils, or the heayier fractions thereof, may be directly utilised for creosoting purposes, or as ing'redlentsof creosoting compositions. Inasmuch as these oils-are clean oils, i. e. free or substantially free from tarry impurities, they may advantageously be treated for the separation of tar acids therefrom, so that the t8!,801dS'l3llllS directly recovered, as weljlas and blend with vapors and the resulting neutral oils, form valuable products of the process. a

In the operation of the apparatus illustrated and described, the coke oven gases are maintained at a high temperature by preventingundue coolin in the collector m am so that they pass to t e electrical precipitator at a high temperature, for example, a-

continuously thereto and the hot pitch and raw tar coming together in flowin streams andcollecting in the bottom of t e recep-. tacle 25 admix with each other while they flotv therethrough, with resulting equalization of tem erature and driving off of water and lower oiling point oils rom the tar.

The resulting hot homogeneous mixture then flows continuously through the line 27 to the receptacle'28. The fuel composition is advantageously kept hot in storage tanks and may be circulated therefrom to the burners and circulation continued b a return line 27 to the tank which keeps t e contents of the tank in circulation.

In the apparatus of Fig. 2 corresponding parts are indicated with the same reference character as in Fig. 1, and Figs. 3 to 5, with the reference character appended thereto, but the electrical precipitator has an enlarged lower portion provided with baflles 29 and 30. The tar inlet pipe for the raw tar is shown at 26a, the tar flowing in over the bafiles 29 and 30, while the pitch continuously separated from the hot coke oven ases also flows down over these bafiles an admixes with the raw tar and the resulting mixture collects in the bottom of the lower compartment of the precipitator and flows out through the line 20a to the collection or storage tank. Inthis modification of the apparatus, the tank 25 of Fig. 1 can be omitted and the chamber in the lower part of the precipitator can be utilized for the continuous admixture or blending of the hot directly recovered pitch and the raw tar.

Any water vapor and vapors of light oil driven off from the tar during this blending operation will admix with the hot coke oven gases passing through the precipitator. Some further distillation may take place due to the contact of the hot gases with the mixture of pitch and tar flowing through the bottom of the precipitator. This will in turn somewhat cool the gases and tend to throw down add ional oil components therefrom with a. tendency to produce a pitch of lower melting point. In this case the melting pointcan be regulated by regulating the temperature of the gases so .that even after they are somewhat cooled by contact with the composition in the bottom ofthe precipitator they will still have the desired temperature when they ass through the precipitator. Where it is esired to recover the vapors given off by the blending of the hot pitch and 1 tar these may advantageously be returned from the mixing compartment to the line containing the coke oven gases. In Fig. 1 the pi 29' provides for passing these vapors w en desired directly from the mixing chamher 25 to the line 24: where they admix with the vapors going to the condensing system.

This enables all va ors given off from the blended product to e recovered in the ordinary condenser system of the coke oven plant.

The precipitator illustrated in detail in Fig. 2 and in Figs. 3 to 5, comprises a shell 5 e. g. of cylindrical form having a gas inlet 6 near the lower end thereof and a gas outlet 7 near the upper end, these inlets and outlets being for the introduction of the hot coke oven gases and the exit of the hot cleaned gases. A bafile 8 partially separates the lower chamber'fiifrom the electrode chamber 10. A plurality of tubes 11 is supported in headers 12 and form the positive electrodes of the separator, the shell of which is grounded. Bus-bar 14 supports the electrodes 15 in spaced relation to the walls of the tubes 11. The bus-bar 14 extends through openings 16 into chambers 17 in which insulators 18 support the bus-bar which is connected to any suitable source of high tension current. Coils 19 may be disposed in the chamber 17 around the insulators 18 for heating this chamber and a heating medium may also be passed through the jacket surrounding the tubes by means of inlet and outlet 22 and 23.

In the operation of this electrical precipitator, the gas enters through the inlet 6, passing around the baflle 8 and thence upwardly through the tubes 11, where the high tension discharge between the electrode 15 and tubes 11 effects removal of substantially all solid and suspended articles from the gases in the form of the irectly recovered high melting point pitch which flows down over the.

bafile 8 into the chamber 9 and thence to the outlet pipe 20. Manholes 21 permit access to the interior of the precipitator.

It will be seen that the invention provides an improved method for the production of a new composite pitch product e. g. a fuel product comprising directly recovered pitch, directly recovered from hot coke oven gases, and tar e. g. raw tar blended therewith in a continuous mannerto form a homogeneous mixture of distinctive'composition, and particularly advantageous for commercial pura5 poses e. g. as a fuel pitch, or as a road-treating material. The new composition is valuble for various purposes where blended products of different melting points are required. Simultaneously with the production of the new composite pitch product there may also advantageously be produced oil or oil compositions valuable for creosoting or other purposes.

By high melting point pitch in the claims I mean a pitch recovered in an electrical precipitator from fresh hot coaldistillationgases at a temperature of 150 C. or higher.

I claim:

1. The method of producing a composite pitch product, comprising subjecting fresh hot coal distillation gases containing entrained particles to treatment with an electrical discharge so as to remove said entrained particles at a sufiiciently high temperature to give a pitch of high melting point and to leave oils, including high boiling oils, in the form of vapors carried by the gases, continuously collectin and drawing off the directly recovere pitch and continuously blending or admixing coal tar therewith while it is still hot and thinly fluid to give a composite and substantially homogeneous mixture.

2. The method of producing a composite pitch product, which comprises subjecting fresh hot coke oven gases containing entrained pitch particles to an electrical discharge so as to separate pitch therefrom-at a temperature suificiently high to give a high melting point pitch and to leave oils, including high boiling point oils, in the form of vapors, continuously collecting the pitch so separated and continuously admixing the same while still hot and thinly fluid with coal tar in proportions to give a hot substantially homogeneous mixture.

3. The method of producing a com osite fuel product comprising subjecting free hot coal distillation gases containing entrained pitch particles to an electrical discharge at a sufficiently high temperature to separate a pitch of high melting point from the gases and to leave oils, including high boiling oils, in the form of vapors carried by the gases, continuously collecting and drawing 01f the directly recovered itch and continuously blending or admixing coal tar therewith while it is still hot and thinly fluid to give a composite and substantially homogeneous fuel mixture.

4. The method of producing a composite fuel product, which comprises subjecting fresh hot coke oven gases condensing entrained pitch particles to an electrical discharge so as to separate pitch therefrom at a temperature sufiiciently high to give a high melting point pitch and to leave oils, including high boiling point oils, in the form of vapors, continuously collectin the pitch so separated and continuously a mixing the same while still hot and thinly fluid withcoal tar in proportions to give a substantlally homogeneous fuel mixture.

5. The method of producing a composlte itch product which comprises sub ecting esh -hot coke oven gases containing antrained pitch particles to an electrical d1scharge so as to separate pitch therefrom at a sufliciently high temperature to give a h gh 10 melting point pitch and to leave high boiling point oils in the form of vapors and collecting the hot pitch and admlxing it while still hot and thinly fluid with coal tar in proportions to give a substantially homou geneous mixture.

6 The method of producmg a composite itch roduct which comprises subjecting resh liot coke oven gases containing entrained pitch particles to an electrical disno charge so as to separate pitch therefrom at a temperature sufficiently high to leave high boiling point oils in the form of vapor, subjecting other fresh hot' coke oven gases to cooling to, separate heavy tar therefrom and 25 to leavetarry oils therein and blending the pitch while still hot and thinly fluid with the heavy tar; I

- The process according to claim 2 in which the hot gases are subjected to an elec-' 3o trical discharge ata temperature in excess of 150 C.

8. The process according to claim 2 in which the hot gases are subjected to an electrical discharge at a temperature in excess of 200 O.

9. The process according to claim 2 in which the hot gases are subjected to an electrical discharge at a temperature in excess of 250 C. 40 In testimony whereof I afiix my signature.

STUART P. MILLER.

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