US1962515A - Production of granulated pitch - Google Patents

Description

S. F. MILLE PRODUCTION 0F QRANULATED BITCH Filed oct. l22. 192A? 2 Sheets-Sheet 1 /gVENTO ATTORN EYS @ZZ- 115m June 12, 1934..4 P. M'ILLR l,962,515

PRODUCTION OF GRANLATED FITCH :Filed 0G13. 22, 1927 2 Sheets-Sheet 2 s INVENT-OR BY 79 wlmfud ATTQRNEYS Patented June 12, 1934- PATENT OFFICE PRODUCTION 'OF GRANULATED Prron Stuart Parmelee Miller, Englewood, N. J., as-

signor to The Barrett Company, New York, N. Y., a corporation of New Jersey Application October 22, 1927, Serial No. 227,927

3 Claims.

This invention relates to improvements in the operation of coal carbonization plants such as coke oven plants, andmore particularly to improvements in the working up of tar at such 5 plants, with 'production of a high yield of mercharitable oils and the production of improved coke.

According to the present invention, the production of tar from coal distillation gases is combined with the distillation of tar by direct Contact with hot coal distillation gases, with the resulting production of distillate oils and a pitch residue, and the lpitch is returned in admixture with coal and there subjected to coking with resulting production of coke and of additional distillate therefrom, which is subsequently recovered from the coal distillation gases. The present invention makes possible the production of a high yield, which may approximate the maximum yield, of distillate oils from tar, with production of a high melting point pitch well adapted for admixture with coal for charging to the ovens, and with return of this pitch to the ovens, there to be converted into pitch coke and additional distillates. A

In the usual Operation of by-product coal distillation plants the hot gases from the ovens or retorts are rapidly cooled by ammonia liquor, or ammonia liquor and tar, in the collector or hy- 30 draulic main, and the greater part of the tar constituents are separated from the gases in the main as a heavy tar which is run off togetherwith ammonia liquor and separated from the ammonia liquor by decantation. In the opera- 35 tion of a coke oven, for example, the gases leavingthe main pass through a cross-over main to condensers or coolers where the gases are further cooled and where a light tar or tarry oil is separated therefrom. The heavy tar from the collector main and the light tar from the condensers are commonly mixed together and sold as coal tar and shipped to tar distillation plants and there distilled to produce distillate oils and pitch.

The shipment of coal tar from the coal distillation plant to the tar distillation plant involves expense and incidental losses in handling ,and shipment, while the distillation of the tar at the tar distillation plant in externally heated tar stills results in decomposition of a considerable part of the oil content of the'tar, so that the yield of distillate oils is materially less than the normal oil content of the tar distilled, and so that the pitch residue produced by the distillation is materially greater than the pitch content of (citas- 91) the tar distilled. The pitch residue, moreover, has a materially increased free carbon content 'produced by decomposition of oil constituents of the tar distilled. When distilling coke oven tar, for example, in simple stills of 10,000 gallons capacity, heated externally, the oil yield is only around 44 per cent when the distillation is carried to the point of producing pitch of around 300 F. melting point, and coking may begin before pitch of 400 F. melting point is 65 reached. With such low yield of distillate oils, the yield of pitch produced from the tar is correspondingly high. A

'According to the present invention, the tar is subjected to distillation at the coal distillation plant by bringing it into direct and intimate contact with hot coal distillation gases. In addition to eliminating or minimizing llosses and expense of handling and shipment of the tar, such distillation gives an unusually high yield of distillate oils, amounting, for example, in the case of coke oven tar to around two-thirds or more of the tar distilled when the distillation is carried'to the point of producing a pitch around 300 F. melting point, and amounting to three- 80 quarters or four-flfths or more of the tar distilled when the distillation is carried to the point of producing pitch of melting point around 400 F. or higher. With the production of such high yields of distillate oils from the' tar distilled, the 85 amount of pitch produced is relatively small, amounting to only one-third or One-quarter vor less of the tar distilled. The pitch of high melting point so produced forms a valuable material for mixing with coal and charging to the coke ovens for the production of coke. therefrom. Such high melting point pitch contains ordinarily less than one-third its weight of volatile material, and gives around two-thirds or more of its weight of coke. In percentage of volatile material and ofl coke produced it is comparable with the bituminous coals commonly subjected to coking. It has such a high melting point that it does not tend to run to the bottom of the coke Ioven and collect there, evenwhen' present in 100- very considerable amounts, around tento fifteen per cent or more. Such hard high melting point, pitch, moreover, can be handled in thesame' manner that coal is handled, and crushed and disintegrated and mixed with the coal in regu- 105 lated proportionswithout danger of softening and becoming sticky during handling.

In the operation of the coke oven plant, according to the present invention, the plant can,

for the most partbe operated in the usual way,

with cooling of the coke oven gases in the collector main and separation of heavy tar therein, and with further cooling of the gases'in the 'coolers or condensers to separate light tar or tarry oils therefrom. The heavy tar from vthe collector main, andthe light tar or tarry oil from the coolers, can be kept separate, or can be mixed together to form a composite tar. In some cases it is more advantageous to keep the heavy tar separate and subject it to distillation, while keeping the tarry oils for admixture with distillate oil for producing creosoting compositions; in which cases only the heavy tar will be subjected to distillation, or the heavy tar with a part only of the light tar or tarry oil. In addition to the tar produced at the coke oven at which the distillation is to take place, additional tar may be subjected to distillation. This additional tar may be from other coke ovens, or it may be gas house tar, or gas retort tar, water gas tar, etc. v

The hot coke4 oven gases leave the individual coke ovens at high temperature, around 600 to 700 C. or higher, and are capable of distilling an amount of tar many times that recovered from the gases themselves. Accordingly, for distilling the total tar produced from a battery of say sixty ovens, it is necessary to use only the gases from say four to six of the ovens for effecting the distillation. Where tar from another battery or from another source is available, an increased number of the ovens can be employed for distillation; and, if a suicient amount of tar is available, all of the gases from a battery may be employed for tar, in which cas the amount of tar distilled will be many times that which the battery itself` would produce.

The distillation of the tar is eiected by bringing it into intimate contact withthe hot coke oven gases, while they are still at a high temperature. By regulating the intimacy of contact of the tar with the gases, and the time of contact, the tar can be distilled to produce a pitch of medium melting point, e. g. around 200 F. or somewhat lower or higher, or a pitch of high melting point, e. g., around 250 F. or 300 F. or 400 F., or even higher, and with distillation from the tar of a large amount of distillateA oil amounting e. g. to around 50 to 80 per cent or more of the tar distilled. For example, in distilling tar to produce a'pitchof about 300 F. melting point, a yield of oil around per cent was obtained, and in distilling tar to produce a pitch of melting point around 400 F., an oil yield around per cent was obtained.

In order to obtain effective distillation of the tar, the gases are advantageously employed immediately after they leave the individual coke ovens, or before their temperature has been lowered materially by cooling; and the tar to be distilled is advantageously brought into intimate contact with the hot gases by atomizing or spraying it into the gases to provide a large surface contact of the tar with the gases. In order to prevent cooling of the gases before they enter in a series of stills in which the tar is progressively distilled and pitch of progressively higher melting point produced. By using the hot coke oven gases at a high temperature it is readily possible to distill the tar to produce pitches having melting points of around 300 F., or higher. Pitches of lower melting point, e. g. 250 F. or lower can be made with ease. Such distillation eliminates the objectionable local over-heating of the pitch in contact with externally heated walls of a tar still. The heat is applied to the outside of the tar particles atomized into the gases, so that the undistilled part of the tar particles will in general be at a lower temperature than the gases, while the vaporization of oil components from the tar particles tends to keep these particles cooler than the gas with which they are in contact. The distillation of the tar to pitch of any particular melting point by this process takes place at radically lower temperatures than is the case when distillation is conducted by indirect heating in externally heated stills. The distillation of the tar takes place in the presence of large quantities of inert gases. The vaporizing temperature of the oilsdistilled is, under the conditions prevailing, considerably below the normal boiling point of the oils involved. For example it has been found that when the gases leaving the distilling chamber were at about 275 C., pitch of about 400 F. melting point was produced, and oils boiling well above 400 C. were distilled oi. In this case there were available approximately 1000 cubic feet, of inert gas per gallon of tar distilled. Under such conditions decomposition of the oils being distilled from the tar will be greatly reduced as compared with distillation by ordinary methods and oils of boiling points much above those normally recovered can readily be recovered by the process.

The distillation of the tar by direct contact with the hot coke oven gases results in greatly enriching the gases in oil vapors so that the vapor content of the gases, instead of being only around one per cent, as in normal coke oven gases, may be as high as ten or fifteen per cent, or even higher. When the resulting enriched gases are cooled to condense the oils therefrom, there will be obtained a greatly increased yield of oils as compared with the yieldl obtainable from ordinary coke oven gases.

lll

l2 The distillation of the tar is accomplished by This not only results in distillationv o f the tar but also causes a substantial cleaning of the hot gases, i. e. it removes from the gases a considerable proportion ofv the tar fog normally present in coke oven gases. The spray of tar or pitch thrown into the gases readily and rapidly settles out of the gases since the droplets, while of small size, are nevertheless of bulk sufcient to cause rapid settling. It is possible there- 'fore to recover from the gases, after their use for distillation, oils containing relatively much less tar or pitch than is the case with the tarry oils normally recovered from the ordinary condensers of a coke oven plant. 4

Furthermore, when the distillation of the tar is carried to the point of producing a high melting point pitch, there will be a large amount of heavy oils distilledfrom the tar, including constituents which in `an isolated state are of a greasy or resinous and semi-solid or solid character at ordinary temperature, but which in admixture with other oils condensed from the gases, form therewith a homogeneous product, which is iiuid at the temperatures required for creosoting operations. The proportion of heavy tar or pitch contained in the oils will be so low -that these oils can advantageously be employed directly for creosotingpurposes, for example, as substitutes for ordinary coal tar solutions, and, in some cases,

additional tar may be added thereto when the oils are to be used for that purpose. In this way the oils condensed from the enriched gases can be utilized directly as merchantable oils, for example, for creosoting purposes, and their high content of heavy distillates from the tar makes them particularly valuable for that purpose.

The enriched gases can, however, be subjected to a further cleaning operationto separate suspended pitch particles therefrom at a high temperature so that the gases will be clean gases and will contain vapors free from -heavy tar and pitch contamination. 1n such case, the gases on cooling will give directly clean= merchantable oils, for example, creosote oils. The cleaning of the gases at a high temperature is advantageously effected with an electrical precipitator which receives the gases directly from the still and which is insulated or heated to prevent undue cooling of the gases while passing therethrough, so that suspended pitch is separated from the gases without cooling and condensation of any considerable amount of heavy distillate constituents from the gases. The pitch thus separated from the gases in the electrical precipitator may be of similar composition to that produced by the distillation, where the gases are not cooled in passing through the precipitator, or the pitch may be of somewhat lower melting point, where more or less cooling of the gases takes place in the precipitator. The pitch from the precipitator can be kept separate, or it can be advantageously refluxed back to the still and subjected to further distillation therein, or it can be admxed with the pitch discharged from'the still. In this way the total pitch can be,k separated and recovered in a form well adapted for returning tothe coke oven in admixture with the coal, while the total oven gases employed for the distillation, then heavier pitch constituents as part of the pitch residue of the distillation and the oil constituents as part of the distillate oils.

The oil produced when tar is distilled to produce a pitch of around 400 F. melting pont will contain a large amount of heavy constituents of a normally semi-solid or solid character, but which in admixture with the ligher oils form a homogeneous solution. Such oils, when the total distillate is condensed together, form valuable oils for creosoting purposes, and can, as a whole, be used for such purposes. Instead of condensing the total oils together, the heavier oil can be condensed as a creosote oil, and the lighter oil as a tar acid or carbolic oil, from which tar acids or phenols can be directly extracted. When a total oil is to be recoveredas a creosote oil, the gases can be cooled from the high temperature of cleaning to a low temperature around 25 to 30 C., and thereafter passed through the ammonia saturator or absorber. When both a heavy creosote oil and a lighter carbolic oil are to be obtained, the gases can be cooled in the first condenser to a temperature around 125 to 150 C., and thereafter cooled to a temperature around 25P to'30" C. to separate the tar acid oil. Other and different fractions can likewise be collected if desired.

The distillation of the tar can readily be controlled by observing the melting point of the pitch produced and increasing or decreasing the rate of distillation to give a lower or higher melting point pitch product. The pitch will be produced continuously, and can advantageously` be drawn off continuously from the still. The operation can however be conducted as a batch or discontinuous process.

The high melting point pitch has such a high melting point that it requires special handling, and there is danger of solidication of the pitch and clogging of pipe lines unless special precautions are taken. The hot pitch can be run directly on to coal on` a conveyor and permitted to solidify in contact with the coal, but this method is not ordinarily to be recommended. The pitch can also be run to a storage place and there permitted to solidify and then dug out as required,

but this involves unnecessary labor in handling the pitch. The hot pitch is advantageously subjected `to rapid continuous cooling and solidication combined with comminution of the pitch .so that there is directly produced a solidied and comminuted pitch product adapted for handling in the same manner as coal.

This solidication and comminution can be effected indifferent ways. A part*cularly advantageous method Aof cooling and comminution is to run the hot pitch continuously into a trough through which a stream of water is running, so that the hot pitch is brought into contact continuously with a flowing stream of water and is immediately chilled and granulated and the granulated pitch carried away by the water to a place of settling and storage. This method of handling the pitch is simple and convenient and inexpensive in equipment and operation, and it gives a pitch in a particularly valuable form for use in mixing with coal.

sys

Another advantageous method of comminuting the pitch is to run it onto a traveling endless belt of metal cooled underneath by a spray of Water, so that the pitch will be rapidly solidied as claimed in my co-pending Serial No. 352,990,1lled April 6, 1929. When such a metal belt passes over the pulley, the pitch is broken up and dropped from the belt as a broken up material in the form of flakes. Another advantageous method of handling the pitch is to ake it on a rotating roll. This is accomplished by running the pitch into a pan having a rotating hollow metal roll dipping slightly into the pitch in the pan. The roll is cooled internally, e. g. by means of water. The surface of the -roll as it touches the molten pitch must be warm in order that the pitch may adhere to it and be carried up by the roll. This is accomplished by spraying the cooling water onto the top inner surface of the roll at such a rate that the pitch Will be sufliciently chilled to be solid so that it may be scrapedvoff just before the rollV surface reenters the molten pitch. The water warmed by the heat in the pitch runs to the lower surface of the roll.A The Water is withdrawn continuously, but a depth of Warm Water equal to 1/4 to 1A the diameter of the roll is allowed to remain at all times in the roll. This maintains the lower roll surface at the proper temperature and prevents local over-cooling due to cold water.

The pitch scraped from the roll is in form well adapted for handling and use.

The pitch is of such high melting point that it can be readily handled around `the coke oyen plant without danger of softening, even in the hottest weather, so that it does not tend to stick to the apparatus in which it is stored or handled. It can be stored in storage bins and handled with the usual coal handling equipment. It can be mixed with coal in the samemanner that different kinds of coal are mixed with each other in regulated proportions, and it can be pulverized the same as coal is pulverized and mixed therewith to form a substantially homogeneous mixture for charging to the coke oven.

The amount of hard pitch added to the coal charged to the coke oven can be varied. Where only the tar" produced by the coke oven is available for distillation, and where the pitch is to be mixed uniformly with all of the coal gcharged to the oven, the percentage of pitch will only be around one to two per cent of the coal charged. Where a much larger supply of tar is available to be distilled, an increased proportion of pitch can be charged with the coal to all of the ovens. Instead of charging pitch to all of the ovens, a much larger amount can be charged with the coal to a limited number of ovens to produce a coke of much higher pitch coke content. For example, as high as ten or fifteen per cent or more of the high melting point pitch can be admixed with the coal and charged to certain of the ovens without interfering materially with the yield of coke produced since the pitch coke contains a similar content of coke forming material to that contained in the coal, and gives a similar propfrtion of distillates in the coke oven gases.

When a large percentage of the pitch is mixed with the coal charged to a few ovens, the gases from such ovens can advantageously be kept separate, since the distillate from the large amount of hard pitch will be somewhat different from that normally produced from the coal, and, by keeping the gases separate, a somewhat different character of pitch residue and of tar and distillate oil can be obtained therefrom. The gases from the ovens in which a. large percentage of pitch is charged may be employed for the distillation of the tar produced from the gases from the other ovens, in which case the residue from the distillation of the tar will blend with the residue from the gases employed for the distillation, and the oil content of the gases, which contains oil constituents resulting from the distillation of the pitch, will be carried along with the distillate vapors and will be recovered as part of the oil product.

In such a cycle of operations the entire tar from the battery can be distilled in the gases from a few of the ovens, and the pitch resulting from the distillation added to the coal charged to the same ovens, so that the gases from the ovens to which the pitch is so charged will be 'employed for the distillation of the tar. In this way the coke produced from these ovens will 'contain a substantial percentage of pitch coke. A high yield of oil will be obtained from the tar by the distillation, and this oil can be directly recovered as a tarry oil, or, by subjecting the hot gases and vapors to cleaning with an .electrical precipitator at a high temperature, the'oil can then be directly recovered from the gases as clean, merchantable oil, while the pitch thrown down in the precipitator can be returned directly to the coke ovens, or can be subjected to further distillation by contact with the hot coke oven gases.

In this cycle of operation not only will a high yield of oil be obtained from the distillation of the tar, but additional oil will be obtained from the pitch charged to the coke ovens, and this will be recovered from the coke oven gases coming from the coke ovens to which the pitch is charged. In this case the total oil yield from the tar and from the pitch will be recovered from the same gases, i. e., from the gases escaping from the ovens to which the pitch is charged and which' are employed for the distillation of the tar. In this cycleof operations, the tarV distillation and thepitch coke formation will be limited to a part only of the battery, leaving the remainder of the battery to be operated in the usual way. c

Likewise the gases from. those ovens to which a large per cent of pitch has been added can be allowed to blend with the gases from the ovens to which no pitch or less pitch has been added.

The tars can be collected together and can be distilled in coke oven gases from ovens towhich no pitch has been added. It will readily be seen that great flexibility is possible with respect to the handling and treatment of the gases from the ovens in which pitch is ycoked with the coal.

While the percentage of volatile matter in the hard pitch is not high, nevertheless the coking of this pitch gives some additional tar and an increased yield of oil, in addition to that obtained by the distillation of the coal. The total oil yield recovered from the tar will, therefore, be made 'up of that directly recovered by the distillation 0f the tar, together with the additional yield obtained from the hard pitch when it is subjected to coking in the coke oven. In this way, substantially the maximum yield of distillate oil can be obtained and only a relatively small percentage of the total tar will be converted into coke in the coke oven. This conversion of the hard high melting pitch into coke is nevertheless advantageous, and does-not interfere with the normal operation of the coke oven. It gives a high yield of coke in proportion to the pitch employed and an additional yield of oils, in addition to that obtained by distillation of the tar to produce the pitch.

In the preceding description, the production of a hard pitch of high melting point and of ahigh yield of ,oils are more particularly described; and the invention presents special advantages for the production and utilization of such pitch and oils.

Many of the advantages of the invention can, however, be obtained when the distillation of the tar is carried only to the point of producing pitch of medium melting point, for example, around 200 F. melting point, or 'pitch of somewhat lower or higher melting point, and when such pitch is returned to the ovens.

The distillation of coal tar in hot coal distillation gases gives a much higher oil yield than obtained by ordinary distillation of tar in externally heated stills, and it is readily possible to obtain upwards'of 50% of the tar as distillate oils in this way, leaving 50% or less of pitch of medium melting point. low carbon content, and, when returned to the coke oven or retort, will not only supply a large proportion of its weight to the coke produced, for example, around two-thirds of its weight as pitch coke, but it will give additional oils which will escape from the ovens or retorts along with The pitch, moreover, is of the coal distillation gases and can be recovered therefrom along with thetar.

When the tar containing the constituents derived from the medium melting point pitch is subjected ,to distillation for example, to produce medium melting point pitch, a considerable amount of the oils driven off from the pitch in the ovens or retorts Will be obtained as distillates, and only such part of thetar as remains in the form of medium melting point pitch will be returned to the ovens.

In this way the tar produced at a coke oven or retort plant can be completely utilized for the production of coke and of distillate oils, with production of a relatively high yield of .oils by distilling the tar to pitch of medium melting point, and with the production of additional oil from the pitch which is returned to the coke ovens or retorts. Where, for example, the medium melting point pitch gives around two-thirds of its weight as pitch coke in the coke oven, only about one-third of the weight of the pitch will be driven 01T as gases and as tar and oil vapors, etc., and the tar recovered from the pitch,'as well as that recovered from the coal, will be subjected to distillation for the recovery'of distillate oils therefrom, leaving only the pitch residue from the distillation for returning to the coke oven.

Where pitch of intermediate melting point is produced and returned to the coke oven, it may be returned to the same oven, the gases from which are employed for the distillation of the tar, or it can be returned in smaller amounts to a largernumber of the ovens, or to -all of the ovens of the battery. When returned to the ovens the gases of which are employed for distillation, separation of part of the tar constituents of the gases as a pitch residue will take place simultaneously with the distillation of tar by the gases. Where the resulting gases and vapors from the distillation are not cleaned with an electric precipitator, a more or less tarry oil will be directly obtained by cooling of the gases to condense the oil, but this tarry oil will contain only a relatively small percentage of heavy tar or pitch constituents which are unobjectionable for certain purposes, such as when the oils are to be employed for creosoting purposes. When the gases are cleaned at a high temperature with an electrical precipitator, or with a hot pitch scrubber, the oils will'be directly obtained as clean, or relatively clean, oils on subsequent cooling and condensation of the vapors.

The process of the present invention makes possible the utilization of all tar produced at a coke oven plant, and the production therefrom as commercial products of only coke and merchantable oils, such as clean oils, or tarry voils suitable for use for creosotng purposes, together with gas and the usual by-products obtained from coke oven gases, such as ammonia, etc. Even with the production of pitches of medium melting point, a much higher over-all yield of oils can be obtained than by ordinary distillation methods,y

while the destructive distillation which results in the formation of carbon takes place largely in the coke ovens where the carbon content forms part of the coke produced. When distillation of the tar is vcarried to the point of producing hard pitch'of high melting point, e. g., around 300 or 400 F. melting point, a much greater oil yield is obtained from the tar, 'including heavy oils, with a minimum of decomposition of such oils during the distillation, leaving only a relatively small amount of the hard pitch of high melting pointlfor return to the coke oven, and this hard pitch can be returned in relatively large amounts, where desired, to give coke containing a relatively high percentage of pitch coke' intimately combined therewith.

The added equipment necessary at a coal distillation plant for the practice of the invention includes the equipment for distilling `the tar by bringing it intimately in contact with the hot coal distillation gases with provision of an electrical precipitator or other cleaning device where the resulting enriched gases are to be substantially completely freed from suspended pitch particles, separate condensing means where the enriched gases are not passed through the ordinary condensers and decanter for separating ammonia liquor from the oil. Means for handling the high melting point pitch can readily be provided, for example, a trough with water supply for granuiatmg the hot pitch continuouny. The pitch when thus produced, can, if desired, be stored and handled the same as coal.

Where a large percentage of the high melting pitch is admixed with the coal charged to the coke oven, for example, around ten per cent or fteen per cent or more, the resulting coke ,will have a high percentage of pitchcoke intimately admixed and combined therewith,` this amount being. in general similar to that of the hard, high melting point pitch admixed with the coal, inasmuch as the pitch has a similar content of volatile material and produces a similar yield of coke to that of the coal.

Instead of subjecting the total tar, including both the heavier tar in the ,collector main and the light tar from the condensers, to distillation, only the heavy tar can be subjected to distillation, or the heavy tar with a. part only of the light tar, leaving the light tar, in whole or in part, for blending with some of the distillate oil produced from the distillation. distillate oil will contain a large percentage of heavy constituents, and it can advantageously be blended with the tarry oil from the ordinary condensers in proportion to give an improved creosoting composition suitable for use as an improved substitute for ordinary coal tar solution. Such improved composition is described in my prior` application, Serial No. 199,629, led June 17, 1927. The invention will be further described in connection with the accompanying drawings, which are more or less conventional and diagrammatic in character, and which illustrate part of a byproduct coke oven plant adapted for the process. of the invention.

In the accompanying drawings Fig. 1 is a plan view;

Fig.. 2 shows the still in elevation; and

Fig. 3 is a section through the still showing the 135 precipitator.

In the drawings part o1 a coke oven battery 1, is shown, having the usual uptake pipes 2, and collector main 3, common to a number of ovens of the battery. From the center box 4 of the 140 collector main the gases pass through the crossover main 5 to the condensers or coolers 6 and 7, which may be either indirect or direct coolers or condensers but which are shown as direct oondensers provided with lines 8 and 8' for the in- 145 traduction of water or ammonia liquor. From the condensers the gases pass through the line 9 to the exhauster 10, and then to the ammonia absorber or saturator, and light oil scrubbers (not shown).

The parts of the coke oven thus-dev scribed may be operated inthe usual way withy introduction of ammonia liquor, or ammonia liquor or tar, into the collector main to cool the gases passing therethrough, and with drawing off of the tar and ammonia liquor from the crossover main through the line 16 to the separating tank or decanter 17, from which the liquor is collected in the receiver 18, and the tar in the receiver 19. The light tar or tarry oils separated in the condensers 6 and 7, pass through outlet pipes 11 and 12 to separating tank or decanter 13, from which the liquor flows to receiving tank 14, and the tarry oils to receiver 15.

The heavy tar from the collector and crossover mains, or the blended heavy tar and tarry oils, are supplied through lines 20 and 22 to the line 21, leading to the tar still 23. Tar from an outside source can also be supplied through the line 22, and this may be either a heavy tar from the collector main of other coke oven batteries, or total tar, including light tar or .tarry oils, or it may be tar from other sources, such as gas house tar or gas retort tar, water gas tar, etc.

'I'he tar still 23is shown as connected with four uptake pipes 24, leading from four ovens at the end of the battery, but it will be understood that a largeror smaller number of ovens can be connected to this still, that more than one still may, if desired, be provided, and that the still or stills maybe connected to any desired ovens. Mounted upon the still 23 is an electrical precipitator 25, from which the gas main 26, leads to a condenser 27, from which the gases pass through the line 28, to condensers 29 and 30, and then .through the line 36 to the exhauster 10 and to the usual ammonia absorber or saturator, etc., (not shown). f

The still 23 is arranged to receive the hot coke oven gases from the individual coke ovens while .still at a high temperature approximating the maximum temperature of the gases, and it is provided with means for bringing the tar to be distilled into intimate contact with the hot gases. 'I'he particular means illustrated is a roll 38, hav, ing suitable bearings, driven by the electric motor 39 at a high speed This -roll causes rapid spraying of the tar or pitch from the bottom of the still into the hot gases passing therethrough, and the amount of tar supplied through the line 21 is so regulated that the pitch escaping from the still through the outlet 40, will have the desired high melting point. Particles of tar and pitch entrained by the gases will be separated therefrom in the electrical precipitator 25, and returned to the still, leaving cleanedgases, free orV substantially free from suspended pitch particles,

to escape through the line 26 to the condensers.

1n order to utilize the hot coke oven gases .at substantially their maximum temperature, the exposed portions of the internal uptake pipes 24, the still 23, and electrical precipitator 25, are provided with heavy insulation, shown at 47, and this insulation may also be provided around the electrical precipitator tubes as shown at 46. By avoiding or reducing much as possible cooling of the gases passing through the electrical precipitator, the gases can be kept at a high temperature as they leave the top of the precipitator and will carry a large proportion of the vapor content distilled from the tar and pitch, while leaving a high melting point pitch to run from the still through the spout 40.

The cleaned gases escaping through the line 26 will be enriched in oil vapors, and may contain, for example, as high as ten or fifteen per cent or more of oil vapors. These can be fractionally cooled and condensed iirst in the'condenser 27 to separate the heavy creosote oil therefrom, which will contain constituents solid or semi-solid or plastic or greasy at ordinary temperatures in an isolated state, but which when blended with other oils form therewith a homogeneous liquid. The cooling in the condenser 27 may be indirect or direct or in part indirect cooling and in part direct cooling. Lighter oil from condensers 29 and 30 subsequently collected in the tanks 32 and 33 can be returned and sprayed into the top of the condenser to assist in condensing the heavier oils, the lighter oils being themselves vaporized and somewhat fractionated. The heavy creosote oil escapes through the line 34 to a receiving tank 35, and is a valuable heavy creosote oil directly usable and saleable without further treatment.

Further condensation of clean oils will take place in condensers 29 and 30, which are cooled 95 by direct introduction of water or clean ammonia liquor through line 31. The condensed oils are collected in receivers 32 and 33, and the oil from 32 and 33 can, as above described, be returned to the heavy oil condenser to assist in condensing the oil therein. 'I'he lighter oils, as Well as the heavier oils, will be clean oils, directly saleable or utilizable, for example, for the extractionof tar acids therefrom.

Where a total oil only is desired, only one condenser, e. g., 27, will be required and the gases may be cooled in one step down to, e. g., 25-30" C., by use of ammonia liquor or water in a direct condenser; or an indirect condenser may be used.

By regulating the distillation in the still '23, 110 pitch of high melting point can be directly produced. This regulation can be effected by the amount of gases introduced into the still, for example, by connecting a larger or smaller number of individual ovens with the still, so that the gases therefrom will passA through the still. The distillation can also be regulated by regulating the amount of tar introduced into the still. 'Ihe same ovens which are connected to the still through the uptake 24, may also be connected with collector main 3 through uptakes 2, with the usual valves when the gases therefrom are not desired for distillation purposes.

When the tar is distilled to give a high melting point pitch, for example, around 400 F., in 19.5 order to obtain approximately the maximum oil yield, and particularly heavy constituents which are valuable in creosoting compositions, precautions must be taken in handling the resulting high melting point pitch, since its high melting .point g3g makes it solidify readily on reduction of temperature. The pitch outlet illustrated is a short spout entering or leaving the still below the normal level of tarI or pitch therein, and arranged so that the pitch will ilow outwardly therethrough by overflow as fast as it is produced in the still. As shown in Fig. 2, the spout is upwardly inclined and is open so that a cleaning rod can be inserted therethrough in case of stoppage or clogging.

From the overflow spout 40 the pitch is shown 140 as ilowing into a trough 41, into which a rapid stream of water is introduced through the pipe 42. This trough is downwardly inclined suiliciently to permit a rapid flow of water therethrough. As the pitch drops upon or into the rapid stream of i4;- water, the pitch is suddenly cooled and chilled and disintegrated into a pulverulent condition and is carried with the water through the trough 41 to a suitable place of storage of the pitch illustrated at 43. This place of storage may be a large E55 sump or bin in which the mixture of water and pitch is received and in which the pitch is permitted to settle and from which the water can be drawn off for recirculation through the line 42 by means of pump 44. By providing a plurality of pitch receptacles or storage places, the pitch can be accumulated and the water permitted to drain oil therefrom in one receptacle While another is .being lled. Y

From the pitch receptacle the pitch can be handled with a grab bucket or conveyer, the same as coal is handled and conveyed to the mixing bin, and mixed With the coal in proper portions and then passed with the coal to the Crushers and then to the storage bin, from which the lorry or coal-charging car is charged for charging the individual ovens. The direct granulation of the pitch places it in a condition Well adapted for further handling and admixture with the coal. The water will readily drain therefrom to a suicient extent to permit the pitch to be employed for mixing with the coal without special drying.

In case a small proportion of the hard pitch is mixed with the coal charged to all of the ovens, the distillate from the pitch, as well as the distillate from the coal, will largely be collected in the ordinary tar collecting system.

In case, however, the pitch is charged in larger proportions, around ten per cent or more, with the coal charged to the ovens connected to the tar still, the resulting coke oven gases from the coking of such charges and containing the products of distillation of the hard pitch as well as the tar from the coal, will pass through the tar still and will be there employed forthe distillation, and such heavy tar constituents, as well as lighter tar constituents produced from the hard pitch during the coking thereof, will be recovered as clean oils from the gases from the tar still, or as high melting point pitch for returning to the coke ovens for further operation. The pitch charged to the oven with the coal will during the coking operation7 undergo destructive distillation and will yield coke, xed gases and tar or tarry oil.

The practice of the process of the present invention enables the coke oven or retort plant t0 dispose within the plant of its entire tar production, and, if desired, additional tar to produce saleable oils, coke and gas and the normal byprodutsf-light oils and ammonia. The production of ordinary pitch as a residue or end product will be eliminated and substantially the maximum yield of oil can be obtained when desired, while the high melting point pitch will in turn give additional oil and a high yield of coke with resulting improvement in the coke produced at the coke oven or retort plant. This improvement in coke results from the fact that the coke resulting from the pitch is at least 95% fixed carbon, there being very little ash in the pitch. Furthermore,

the pitch coke is very much stronger than is coal coke.

Where part of the light tar or tarry oil collected in the receiver 15 from the condensers is not returned for distillation, part or all of this tarry oil may advantageously be mixed with the clean oils resulting from the distillation of the tar. The large content of heavy constituents which such oils contain, makes them well adapted for blending with the tarry oils for making creosoting compositions. When the electrical precipitator 25 is not provided in the equipment, and when the gases are not so cleaned to separate suspended pitch particles therefrom, or where only partial separation takes place in mechanical or centrifugal or other separator, the distillate oils may contain more or less pitch or tarry matter therein, but the proportion of such material will be relatively small so that the oils may, nevertheless, be employed directly as merchantable oils for creosoting and other purposes, or for blending with the tarry oils directly recovered from the coke oven gases and collected in the receiver 15. It will thus be seen that the present invention provides for an improved operation of by-product coal distillation plants whereby improved coke can be produced, and whereby a high yield of valuable oils can be directly produced, requiring no further treatment, and whereby all of the heavier tar constituents, not so recovered as oil, are utilized for the production of coke and for the production of additional oil by distillation, so that only coke, merchantable oils and gas (with ammonia) are recovered as by-products of the coke oven or retort operation.

I claim:

1. The step in the production of a granulated pitch, which comprises continuously bringing a stream of hot molten pitch and a stream of water into contact so that the stream of water breaks up the stream of pitch thereby continuously and simultaneously chilling and granulating the pitch.

2. The steps in the production of a granulated pitch, which comprise continuously withdrawing pitch from a still in the form of a stream and running the stream of pitch into a jet of water directed away from the still so that the jet of water breaks up the stream of pitch, whereby the pitch is simultaneously chilled and granulated and simultaneously removed from the vicinity of the still.

3. 'I'he steps in the production of granulated pitch, which comprise running a stream of hot molten pitch into a concurrently flowing stream of cold water thereby chilling and granulating the pitch, separating the pitch thus granulated from`the water and reusing the water to form said stream of cold water.

STUART PARMELEE MILLER.

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