US1925150A - Pitch composition and method of making same - Google Patents

Description

Sept. 5, 1933.

S. P. MILLER- 1,925,150

PITCH COMPOSITION AND METHOD OF MAKING SAME Filed Aug. 17, 1927 2 Sheets-Sheet 1 INVENTOR WWW ATTORNEYS Sept. 5, 1933. v s MlLLER v 1,925,150

PITCH COMPOSITION AND METHOD OF MAKING SAME Filed Aug. 1'7, 192'? 2 Sheets-Sheet 2 INVENTOR ATTORNEYS Patented Sept. 5, 1933 rrrcn COMPOSITION AND METHOD or MAKING SAME Stuart Parmelee Miller, Glen Ridge, N.J., assignor to The Barrett Company, New York,

N. Y., a corporation of New Jersey Application August 17, 1927. Serial No. 213,497

2 Claims. (Cl. 202-30) This invention relates to a new pitch composition and to an improved method for producing the same. The invention also includes improvements in distillation of tar, and in the recovery 5 and production of valuable products therefrom.

In order to produce heavy or high boiling pOint oils from tar by ordinary distillation methods, it is necessary to carry the distillation to a high temperature. Such distillation is accompanied with a very considerable decomposition of oil constituents of the tar, so that the yield of oils recovered by distillation is considerably less than that contained inthe tar distilled, while an increased amount of pitch is produced, partly by,

decomposition during the distillation, and the pitch has a high carbon content.

Such distillation of tar is commonly carried outat tar distillation plants located at a greater or less distance away from the coke oven plant at 29 which the tar is produced. The tar separated from the coke oven gases by cooling and condensation is collected and transported to the tar distillation plant and there subjected to distillation. Such procedure is accompanied by cost of transportation and losses of tarincidental to its handling and shipment, while the distillation of the tar,is accompanied with further loss of oil by decomposition and increase in the amount of pitch and carbon content of the pitch produced.

Y 30 as a residue of the distillation. When such high carbon pitch is blended with ordinary tar, the high carbon content of the pitch may interfere materially with the blending operation and may result in settling out of some of the carbon with 85 resulting lack of homogeneity of the blended product and with liability pf clogging of pipe lines, etc., where the resulting blended product is used for fuel or other purposes.

The present invention eliminates the necessity 4| of the transportation of tar from a coke oven oven plant, and distillation is so carried out as to produce a hard or high melting point pitch, which will, nevertheless, have a much lower carbon conby the hot coal distillation gases.

tent than the pitch produced by ordinary tar distillation methods in externally heated tar stills; and this pitch directly produced by such distillation is then blended with tar to form a composite product valuable, for example, for use 80 as a fuel composition in open hearth furnaces, etc. The production of the pitch in this way,

is accompanied by the production of a high yield of oils, including heavy or high boiling point oils, and including oils which, in ordinary tar distillation methods, are decomposed and converted into a pitch residue or into carbon or other decomposition products.

The gases from coke ovens or retorts leave the ovens at a high temperature, around 600 to 700 C. or higher, and are commonly cooled in the collector main of the battery by the introduction I of ammonia liquor or ammonia liquor and tar, directly into the collector main to throw down a heavy tar from the gases, and by further cooling of the gases in the coolers or condensers to throw 'down a light tar or tarry oil therefrom. The heavy tar and light tar are commonly mixed and subjected to distillation. The tar so produced may be employed in the process of the present invention, and may be tar produced at the same coke oven-plant at which the distillation is carried out or it may be coke oven tar produced at another coke oven plant, or may be in part gas house tar or water gas tar, etc.

According to the present invention, the tar is subjected to distillation by bringing it into direct contact with the hot coke oven gases at a sulficiently high temperature to distill the tar to remove a large part of the oil components thereof, and to leave a pitch residue of high melting point but of relatively low carbon content; and the resulting pitch is then blended with raw tar or with heavy tar, etc., to form the new pitch composition. The distillation of the tar in direct contact with the hot coke oven gases can be carried out, for example, in accordance withathe processes described in my prior applications, Serial Nos. 166,081, 171,955, 172,962, and 181,366, by spraying the tar into the hot coke oven gases at a temperature not greatly below that at which the gases leave the ovens, so as to use the high temperature of the gases for the distillation. Such distillation will take place without external heating of the apparatus in which the distillation takes place, and with heating of the tar only This distillation will remove from the individual particles of tar sprayed into-the gases a large part of the vaporizable components, leaving a pitch residue v which will vary in its melting point with the exthe tar. is not kept in contact with the hot gases for a prolonged period, can be carried out without any considerable increase in carbon content due to decomposition during the distillation, although some such decomposition may take place, particularly where the time of contact of the tar and resulting pitch residue with the hot gases is prolonged. In any event, the pitch residue produced will be of relatively much lower carbon content than pitch residues produced by distillation in ordinary externally heated tar stills, while a considerably increased oil yield can be obtained by distillation from the same amount of tar, as compared with the oil yield produced by distillationin ordinary tar stills. The present invention, accordingly, forms valuable process for the distillation of tar where a part only of the tar is to be distilled, and where the maximum oil yield is desired from the tar and where the pitch residue is to be employed for blending with the remainder of the tar for fuel or other purposes.

The distillation of the tar and the production of the pitch, according to the present invention, are advantageously carried out as a continuous operation, with the continuous production of a hard, high melting point pitch, and with the continuous blending of such pitch with raw tar to produce the new composite pitch composition. The tar can be introduced, for example, directly into a still through which the hot coke oven gases are passing and the rate of distillation regulated or the tar recirculated and further distilled, to givecontinuously a high melting point pitch; and this pitch as produced can then be advantageously blended continuously'with a stream of raw tar to form continuously the blended composite pitch products.

The hot coke oven gases coming from the individual coke ovens at a high temperature are capable of distilling an amount of tar many times that which is produced from the gases from a single oven. Accordingly, in a coke oven plant where the tar to be distilled is that produced at the same plant, the gases from a few only of the ovens will suifice for the distillation of the tar produced from the remainder of the battery. Where, however, the tar from several batteries is to be distilled, the gases from an increased number of ovens, or from an entire battery, or from so much of a battery as is connected to a single collector main, may be employed for the distillation. By bringing the tar intimately into contact with the hot gases at substantially their maximum temperature as they leave the coke oven, the tar can be continuously distilled in a single operation to produce substantially the maximum yield of distillate and a hard high melting point pitch residue, which can be drawn off continuously and blended continuously with raw tar, etc., to form the new pitch composition. In order to obtain substantially the maximum yield of distillate, the distillation can be carried to such an extent that pitch of high melting point, for example, pitch of 300 F. melting point, can be produced; but the further distillation can advantageously be carried to such an extent that a much higher melting point pitch is produced, such as a pitch of melting point around 400 F., or in some cases as high as 500 F. The di illighter oils, blend therewith to form a homogeneous product. r

The blending or mixing of the pitch with the tar can be carried out as successive batches by adding the hot pitch gradually to a tank ,of hot tar, or vice versa. It can also advantageously be carried out in a continuous manner by running streams of pitch and tar continuously into a" mixing box or receptacle in which the streams blend and mix with each other to form a homo-' geneous product, with further agitation, if necessary, and by continuously discharging the resulting homogeneous mixture from the mixing chamber. When tar is distilled'to produce pitch of highmelting point, and where the pitch is directly blended with raw tar, the hot pitch will heat the tar and result in a heated mixture from which moreor less distillation may take place, due to the heating of the tar to a temperature above the distillation temperature of some of its constituents. tar may be removed and recovered as a distillate oil, or may be refluxed back and blended with the pitch composition. Raw tar which contains water will be dehydrated by the mixing operation, but by running streams of the raw tar and hot pitch into a mixing box, any foaming due to the removal of water will be taken care of without interfering with the mixing operation.

The resulting blended product made by blending the hot pitch and tar can be employed for various purposes, such as for fuel purposes, as fuel in open hearth furnaces, etc.; or it can be employed for other purposes where a blended pitch and tar product is desired, for example, for road-making purposes, or for roofing, etc.

The tar which is blended with the hot pitch may be part of the tar produced at the same coke oven plant, or it may be tar from another plant, or gashouse tar, etc. tar, including both the heavy tar from the collector main and the light tar or tarry oil from the condenser, only the heavy tar from the collector main may be blended with the hot pitch,

leaving the tarry oil from the condensers to be employed for other purposes. Such tarry oil can advantageously be blended with the distillate condensed from the enriched gases resulting from the distillation of the tar and production of the pitch, and a blended product may thus be obtained which can be employed directly for creosoting or other purposes. The present invention includes the production of such a blended productfrom the distillate and from light tarry oils as Well as the production of a composite pitch product from the pitch residue of the distillation and the heavy tar from the collector main.

The distillation of the tar by the hot coke oven gases will result in a very material enrichment of the gases in oil vapors, and the oil condensed from the resulting enriched gases will contain a relatively low content of heavy tarry matter, since they will be made up largely of the distillate oils and will contain a relatively small amount of oils and heavy tar directly condensed from the gases employed for the distillation and originally carried thereby before the enrichment by the distillation. The enriched gases can be employed with whatever heavy tar or pitch constitutents they contain and blended,

Instead of using the total The oils so distilled from the ,for example, with the light tar or tarry oilsdirectly produced from coke oven gases in the ordinary condensers or coolers of the by-productrecovery system. In such case, only the heavy tar from the collector mains may be subjected to distillation for the production of the pitch residue, and the light tar or tarry oils from the condensers may be kept separate and blended with the distillate from the distillation of the heavy tar in such proportions as will give, for example, a creosote composition suitable for use as asubstitute for ordinary coal tar solution. -Such a creosote composition is describedin my prior application, Serial No. 199,629.

The gases produced by the distillation can be subjected to a cleaning treatment at a high temperature with an electrical precipitator to remove suspended pitch particles therefrom, and to leave only gases carrying only clean oil vapors, from which clean oils free from tar can then be directly condensed. In this case an added amount of pitch will be recovered from the electrical precipitator, which may be blended withthe pitch resulting from the distillation. In this case; only pitch and clean oils will resultfrom the distillation, and the clean oils may be recovered as merchantable oils, for example, clean creosote oils, or as a creosote oil fraction and a tar acid oil fraction, as described, for example, in my companion applications Serial Nos. 206,366 and 206,367.

The new pitch composition of the present invention differs greatly from compositions made by mixing tar with pitch produced by distilling tar in simple, externally heated tar stills. In

such stills of, for example, 10,000 gallons capacity,

where successive charges of tar are heated and distilled by the application of external heat to the still, the yield of distillateoil is relatively. small, and the amount of pitch produced is large and the pitch is high in free carbon, and particularly in carbon produced by decomposition during the distillation. Tar distilled in such stills to produce a pitch of melting point around 170 F. gives an oil yield of only about 33 per cent of the tar distilled; if the distillation is carried further to produce a pitch of around 200 F. melting point, the oil yield is only about 38 per cent,

while if the distillation is carried still further to produce a pitch of around 300 F. melting point, the oil yield is increased only to about 44 per cent, and coking of the tar may begin before pitch of a melting point of around 400 F. is

reached. The distillation of tar with hot coke oven gases, as carried out in producing the new pitch composition, gives a radically increased yield of oils and a corresponding reduction in the amount of pitch and an entirely different character of pitch. For example, 'in distilling certain coke oven tars by direct contact with hot coke oven gases where the time of contact is short, the distillation of the tar to produce a pitch of a melting point around 170 F. gives an oil yield around 48 per cent; while with distillation to produce a pitch residue of melting point around 200 R, an oil yield around 55 per cent or higher can be obtained; and if the distillation is carried so far as to produce pitch of a melting point around 300 R, an oil yield around '70v per cent can be obtained; and it is possible to carry the distillation to produce pitch of 400 F. melting point and higher, with a yield, for example, around percent of oil when 400 F. melting point pitch is produced. Comparing, ior example, the pitches of melting point around 300 F. produced respectively in ordinary externally heated tar stills of the type above mentioned, and pitch of similar melting point produced by direct distillation with hot coke oven gases, it will be seen that the yield of oils is only about 44 per cent in\one case and around 70 per cent in the other. The remaining 26 per cent of oil is largely decomposed by the distillation in the ordinary tar stills, with increase in pitch residue. Moreover, this decomposition, due'to local overheating, etc., results in production of l a large amount of carbon, and of carbon of a diiferent character. It includes not only substances commonly called carbon because insoluble in benzol, but it contains considerable elemental carbon or decomposition products insoluble, for example, in anilin, while the so-called carbon contained in the pitch employed in the new composition is readily soluble in anilin and is composed of heavy hydro-carbons, which are readily soluble in, or form a homogeneous composition with, the tar with which the pitch is blended. The ayoidance of the large; increase in carbon of a difierent character in the pitch products employed in the new composition gives an improved composition from which there is little, if any, liability of carbon settling out, for example, in pipe lines by 'whichthe composition is supplied to fuel burners. v

The invention will be further described in connection with the accompanying drawings, which illustratein a somewhat conventional and diagrammatic manner an arrangement of apparatus suitable for the practice of the invention.

In the accompanying drawings,

Fig. 1 shows an arrangement of part of a coke oven plant with part of the by-product recovery system, including an arrangement for distilling tar by direct contact with hot coke oven gases; and

Fig. 2 is an elevation with parts in section of the short collector inain and electrical precipitator of Fig. 1..

In the accompanying drawings, the coke oven 1 has the usual uptake pipes 2 leading to the ordinary collector main 3, having center box 4 and cross-over main 5 for leading the gases to the condensers shown as 6 and 7, which are of the direct type cooled by introduction of cooling liquid, such as water or ammonia liquor, through. the pipes 8, From condensers the gases pass to the exhauster 9, and then to the ammonia absorber and light oil scrubber (not shown).

Ammonia liquor, or'zammonia liquor and tar, is

and to flush the tax; from the collector main 4 through the center box. The outlet for tar and. liquor is indicated at 10 and leads tothe separator or decanter 11, from which the tar flows to the tar storage or receiving tank 12, and the ammonia liquor to the tank 13. The line 15, with pump 14 in it, conveys tar toa short collector main 21 for distillation.

The tarry oils condensed in the condensers 6 and 'I are run ofi through lines 16 and 17 and may be collected together in the receiver or decanter 18, from which the ammonia liquor is collected in the receiver 20,'and the tarry oils in the short collector main for such distillation. The

tar is introduced into the short collector main through spray nozzles 23, and is brought into intimate contact with the hot gases passing through I the short collector main, and is thereby distilled and a pitch residue produced. A pump 14' is provided through which the pitch residue may be recirculated. The hot gases coming from the individual ovens are at a high temperature, around 600 to 700 C. or higher, and with insulation of theindividual uptake pipes and of the shortcollector main, these gases enter the short collector main without any considerable reduction in temperature, so that they are available at a high temperature for distillation of the tar. By regulating the tar supply, and by recirculating the resulting pitch if necessary, the tar can be distilled to produce a pitch of high melting point, from which a high yield of oils is driven off.

The pitch residue from the distillation goes through the line 24 to a mixing tank or chamber 25, to which tar' is also supplied in regulated amounts through the line 26. With continuous distillation of tar and continuous production of pitch, the pitch can be supplied continuously to the mixing chamber, together with continuous supply of tar in regulated amount so that the pitch and tar will continually mix in the mixing chamber and the mixture will flow out through the outlet 30 to the receptacle 31 for the mixed product.

The hot pitch will enter the mixing chamber 25 at a high temperature, while crude tar, or even wet tar, may enter through the line 26 at ordi nary temperature. The heat of the hot pitch will serve to heat the tar with which the pitch admixes, and this in turn willserve to dehydrate the tar and removetherefrom more or less of the oils volatile at the temperature of the resulting mixture. Some foaming may take place where the hot pitch and the wet tar come into contact with each other, but this will be unobjection'able, because the mixing chamber 25 can be kept nearly empty, that is, with only a layer of thefiowing mixture in the bottom, so that any foam formed will be taken care of. The-mixing chamber 25 may be supplied with an agitator to promote the intermixture of the tar and pitch, but, ordinarily this will not be necessary where regulated streams of the two materials are suitably brought together in the mixing chamber. The hot pitch, because of its low carbon content, and because the carbon content which it contains is largely made up of heavy hydrocarbons, readily blends with the tar to form a substantially homogeneous mixture with little, if any, tendency for the separation of carbon therefrom during storage and circulation to burners, etc. A

Oils vaporized in the mixing chamber can be condensed by the condenser 27 and either re turned to the mixture of tar and pitch through the line 28, or drawn off as condensate through.

the line 29 and employed as an oil for other purposes.

be materially enriched in vapors due to the distillation. These gases pass through the line 32 to the condensing-system shown in two condensers 34 and 35. The gases may be passed to this condenser without further treatment by cleaning, but are advantageously subjected to cleaning with an electrical precipitator at a high temperature to recover suspended pitch particles therefrom rating the suspended pitch particles therefrom,

' covered in the main condensing system in proper a pitch in the form of a pitch product which can advantageously be added as part of the new fuel composition. The gases from the short collector main will leave it while still at a high temperature, and if passed through the electrical precipitator without material cooling, will carry pitch particles of relatively a high melting point pitch and will carry a large amount of oils in the form of vapors. By treating the gases and sepathe pitch can be employed in making the new pitch composition while the gases can be subjected to cooling and condensation to recover directly therefrom clean oils, free or substantially free from heavy tar and pitch impurities. These clean oils will be condensed in the condensers 34 and 35 which may be of the indirect type, i. e., cooled by indirect contact with water, so that a heavy creosote'oil and a lighter tar acid oil can be directly recovered therefrom. The gases then pass to the exhauster 36 and to an ammonia absorber, etc., (not shown).

The clean oils recovered in the condensers 34 and 35 may be blended with the tarry oils reproportions to give a creosoting composition; or only the heavy condensate from the condenser 34 may be so employed. If the gases are not cleaned with an electrical precipitator, they will carry more or less heavy tar and pitch constituents with them, and the oils condensed in the condensers 34 and 35 .will be tarry oils. They will differ materially, however, from the tarry oils collected in the receiver 19, because they will be recovered or condensed from enriched gases, and willcontain relatively little pitch and heavy t'ar constituents. The tarry oils from the respec- 'tive systems can advantageously be blended in proper proportions to give directly a creosoting composition suitable for use as an improved sub- 5 stitute for coal tar solution.

The apparatus illustrated includes the byproduct recovery system of an ordinary coke oven plant in which ammonia liquor is employed for cooling the gases in the collector main, and in 2 which a heavy tar is separated from the collector main and tarry oils from the condensers. In

addition, the apparatus illustrated includes a tar still for distilling the tar by direct contact with hot coke oven gases from part of the battery so.

as to produce from this tar a pitch residue and distillate. oils which may be clean distillate oils,

or which may be tarry oils. The pitch residue is then blended with tar to'form the new fuel composition. The oils resulting from the distillation may likewise be blended with the tarry oils from the ordinary recovery sytem to make a creosoting composition, while 0 y the heavier tar from the collectormain of the ordinary system may be subjected to distillation to produce 5 I residue and distillatebils thereform.

The present invention involves the production of a new fuel composition, in which the pitch directly produced by distillation of tar with hot coal distillation gases and of the distinctive comi position resulting from such distillation is blended The gases leaving the short collector main will with tar or heavy tar or tar from another source such as gashouse tar, or water gas tar, to make a new composite product suitable for use, for

in a manner which makes the pitch available to advantage for fuel and other purposes. The composite pitch product can be employed, for exam ple, for roofing purposes, or for road treating purposes, etc. Simultaneously with the production of the new pitch composition, there may advantageously be also produced a creosoting composition by blending the distillate oils resulting from the distillation with directly recovered tarry oils in suitable proportion.

In this way the total tar produced by the coke oven plant may be used up and converted into the new fuel composition andfmto compositions suitable for use directly for creosoting purposes. When the tarry oils, as well as the heavy tar from the ordinary by-product system, are subjected to distillation to produce the pitch for blending to make the new product and to produce distillate oils, the distillate oils can be employed as such or blended with other products. Instead of working up all of the tar from the coke oven battery by distillation, part of it may be employed for blending with the pitch produced by the distillation, or the pitch so blended may be tar from another source, and even tar of different properties, such as, for example, water gas tar. Fuel compositions made from the high melting point low carbon pitch and water gas tar are advantageous, inasmuch as water gas tar itself is not suitable for distillation to give distillate oils suitable for certain purposes, such as creosoting purposes, or it gives distillate inferior for that purpose. By subjecting coal tar to distillation to recover creosote oils, and then blending the pitch residue with water gas tar, a valuable fuel composition is obtained.

cooling hot untreated coke oven-gases to sepa-' rate therefrom first a heavy tar and thereafter a light tar, subjecting the heavy tar to distillation by bringing it into direct contact with hot coke oven gases, at substantially the temperature at which they leave the ovens to produce a pitch residue of high melting point and gases enriched in oil vapors, mixing the resulting hot pitch residue with tar to form a homogeneous pitch composition, cooling the enriched gases to condense oil vapors therefrom and mixing the oil condensed from the gases with the light tar to form a composition suitable for use for creosoting purposes.

2. The method of producing composite pitch compositions and clean oils, which comprises subjecting tar from gasification or coal carbonization processes to distillation by bringing it into direct contact with hot coke oven gases to produce a pitch residue of at least 300 F. melting point and gases enriched in oils, subjecting the resulting gases to cleaning with an electrical precipitator to separate suspended pitch particles therefrom, combining the pitch from the precipitator and the pitch residue from the distillation while still hot and without substantially increasing the free carbon content of either with tar to form a composite pitch composition, and recovering clean oils from the gases resulting from the distillation.

STUART PARMELEE MILLER.

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