US1959290A - Distillation of tar - Google Patents

Description

:s sheets-sheet 1 S. F. MILLER DISTILLATION OF' TAR Original Filed Dec.

May l5, 1934.

NVENTOR ifm ATToRNEY May 15, 1934. s. P. MILLER DISTILLATION OF TAR Original Filed Dec. 1l, 1929 3 Sheets-Sheet 2 Fig .JL/ Hrm ya INVENTQR 5, PM BY @@wg f M ATTORNEY5 May 15, 1934. s. P. MILLER DISTILLATION OF TAR originan Filed Dec. 5 sheets-sheet s l Patented. May 15, 1934 UNITED STATES y,PATENT OFFICE to The Barrett Company, New York, N. Y

corporation of New Jersey Application Decemberll, 1929, Serial No. 413,252

Renewed December 14, 1933 n 7 Claims. (Cl. 202-30) This invention relates to the distillation of tar by direct contact with the hot gases from a plurality of gas retorts. The hot gases from a number of retorts are collected togetherand passed into a still, the tar to be distilled is brought into direct contact with the hot gases in the still and pitch is produced. The invention includes both the process and apparatus for carrying it out.

In a gas retort plant such as a horizontal gas 10 retort plant, the retorts are ordinarily arranged in tiers with four to six or more retorts in each tier. A single vertical pipe called a multiple standpipe is often employed to collect thegases from all of the retorts in one tier or from all of the retorts in two adjacent tiersjand to convey these combined gases to the hydraulic main or other gas collector main. According to this invention a multiple standpipe, which may .be similar to the usual standpipe, is employed, but the standpipe of this invention is heavly insulated and the gases are conveyed to a still and employed for the distillation of tar. The gases from several such standpipes may advantageously be combined and conveyed to one or more stills, which may be located on top of the gas retort bench or adjacent thereto. 'Ihe gases from all'of the retorts in a tier or all of the retorts in two adjacent tiers are collected in a single standpipe and the gases from a number of retorts are supplied to a single still and employed for the distillation of tar in this still. The pipes connecting the still with the retortsand the still itself are heavily insulated so that the gases enter the still at a high temperature approaching the temperature at which they leave the retorts.

The temperature and quantity of the gases generated in a retort vary during the distillation of a single charge of coal in the retort. A large quantity of gases of relatively lower temperature are evolved during the earlier stages of the distillation, and during the later stages less gases, but gases of higher temperature are evolved. By combining the gases from several retorts charged at intervals, and preferably charged in rotation so that no two retorts are charged at the same time but the time between the charging of any two or more of the retorts is substantially the same, gases of relatively constant temperature are obtained and in relatively uniform quantities. According to this invention the gases from a number of retorts are combined and the heat of the combined gases is employed for the distillation of tar by bringing the tar into direct contact with the hot gases.

Several stills may be provided each connected with the retorts in several tiers.v The tar may be partially distilled in each of the stills, and by being passed through a number of the stills in series a pitch of any desired melting point may be obtained. Where several stills are thus employed in series a portion of the partially distilled tar produced in any one of the stills preceding the nal still may be drawn 01T as a separate intermediate product. The gases and vapors from all of the stills may be combined and treated in the same condensing system to produce a desired total oil or several oil fractions, as desired. Instead of employing a single condensing system an individual condenser or partial condensers may be connected with one or more of the stills in the series to separately collect an oil fraction from any selected still.

Instead of operating the stills in series fresh tar may be supplied to each of the stills so that the stills are operated in parallel and the operation may be so controlled as to produce any desired oil or pitch products.' One condensing system may be connected with all of the stills so that one total oil or several oil fractions are collected from the combined gases and vapors resulting from the distillation in all of the stills. Where desirable a separate condenser or a separate partial condenser may be connected with any one or all of the stills to separate one or more desired clean oil fractions from the gases.

The hot gases and vapors leaving the stills are advantageously employed for preheating the tar to be distilled. A single tar preheater may be provided through which the combined gases and vapors from all of the stills pass. In this Way a clean oil, comprising constituents present in the gases and vapors leaving each of the ovens will be obtained in the heat interchanger. By connecting a preheater with any one or more of the stills individually, one or more tar oil fractions may be separately condensed from the gases and vapors by indirect contact with the tar. By proper regulation a total clean oil or several clean oil fractions may be collected from the gases as desired.

Where more than one still is employed each still is connected with a number of retorts. 'I'he hot gases from two or more tiers of retorts may be combined and passed into each of the stills. 'I'he hot gases from multiple standpipes connected with four tiers of retorts, for example, can be combined with a hot gasvheader through which the gases pass to a still. The hot gases from more than four tiers or less than four tiers may be combined to be passed into the still, where desirable.

Where more than one still is employed the gases to be passed through each of the stills may be separately collected yor the gases from a number,

of tiers of retorts may be collected in a hot gas header and a portion of the hot gases thus co1- lected passed intoeach of the stills.

The invention may be applied to through retorts or to stop-end retorts, or any type of retort built into a bench in which the retorts are arranged in tiers. When the invention is applied to through retorts a gas connection is advantageously made at each end of each of the retorts. One end of the retort is connected with an insulated multiple standpipe leading to a still and the other end is connected with the ordinary hydraulic main. By the proper manipulation of valves in the pipes that connect the same retort with both the hydraulic main and the still. the gases from this retort may be passed into the still or to the ordinary hydraulic main and the ordinary recovery system. With such an arrangement the hot gases and vapors from any number of the retorts may be passed to one or more of the stills as desired and the balance of the hot retort gases will be passed into the hydraulic main and thence to the usual condensing system.

The temperature at which the hot coal distillation gases leave a gas retort varies somewhat depending upon the kind of Acoal being distilled, the

coking cycle, etc. Ingeneral the gases leave the retorts at temperatures in the neighborhood of.

500 C., but the temperature may vary above and below this depending on the coking conditions and coking cycle. The temperature of the gases is suiliciently high to carbonize tar and form coke when brought into direct contact with the tar. Therefore, when the gases are employed for the distillation of tar the tar is sprayed into the gases in the form of such a fine intense spray that the gases are rapidly cooled to approximately the temperature of the tar and the tar is rapidly distilled. Such an intense spray of tar is maintained in the still at all times that the heat of the gases is quickly absorbed as sensible heat in the pitch and vapors produced and as latent heat in the oil vapors resulting from the distillation. The entire still is advantageously iilled with a ilne intense tar spray and the walls of the still are washed with the tar so that the accumulation of pitch or coke on the walls of the still is prevented. The word tar in this patent includes raw tar, dehydrated tar or stripped tar from which some of the more volatile oils have been removed. i. e. semi-pitch.

Where several stills are employed in series the distillation residue from the first still is sprayed into the hot gases in the second still of the series where it is further distilled and in this manner the tar is progressively distilled until pitch of the desired melting point is produced.

In distilling the tar the flow of the tar and the hot gases may be parallel so that the hottest gases are brought into contact with the coldest tar, and the tar after being in the still for a period gases may be admitted to opposite ends of the still in order to take advantage of the economies inherent in countercurrent distillation.

The hot gases leaving -a gas retort contain fine particles of suspended impurities. These comprise particles of coke, pitch, etc. They can be separated from the gases only by some thorough cleaning operation, such as an intensive scrubbing. According to the preferred method of carrying out this invention the gases are sprayed with such an intense spray of tar that entrained impurities are scrubbed from the gases and the gases as they leave the still are substantially deterred.

It may be desirable to pass the gases and vapors v resulting from the distillation of tar ,in the hot retort gases, up through a settling chamber or bailiing chamber before they enter the condensing system in order to remove entrained particles of tar spray from the gases, so that the oils obtained in the condensing system will be clean oils substantially free from tarry and pitchy constituents. For this purpose a settling chamber or baiiie tower may be provided on each still, or where several stills are employed and only one condensing system is provided, the gases from the several stills may be combined and together passed through the settling chamber or baflie tower before entering the condensing system.l

The invention will be further described in connection with the accompanying drawings but it is intended and is to be understood that the lnvention is not limited thereto.

In the drawings:

Fig. 1 is a plan view of a gas retort plant equipped with several stills for the distillation of tar with parallel ow of the gas retort gases through the stills, and the parallel flow of the tar through the stills;

Fig. 2 is an elevation of Fig. 1;

Fig. 3 is a detail showing a section through one of the stills;

Fig. 4 is a detail vshowing the lvalve arrangement employed for connecting and disconnecting one of the retorts and the hot multiple standpipes:

Fig. 5 shows valve means for connecting or disconnecting one of the retorts and the standpipes connected with the hydraulic main;

Fig. 6 is a plan view ofa gas retort plant with a number of stills and parallel flow of the gases through the stills with means for conveying the tar through the stills in series;

Fig. 7 is an elevation of Fig. 6; and

Fig. 8 is a section through the first still of the series and the settling tower.

In the drawings, 5 indicates a bench of through gas retorts. The retorts 6 are arranged in tiers of ve retorts each. Standpipes 7 connect each of the retorts in the bench with the hydraulic main 8. This main is connected through the foul main 9 with the condensers 10. Tar and ammonia liquor from the hydraulic mainare drawn off into the decanter 11 and the tar and ammonia liquor are separately collected in the tanks 12 and 13, respectively. A pipe is shown at 14 for supplying ammonia liquor from thetank 13 to the hydraulic main. This apparatus may be of the usual type.

At the opposite end of these retorts from the end at which the standpipes 7 are connected. multiple standpipes 15 are provided, each of which is connected with all of the retorts in two tiers. Several of these multiple standpipes connect with a hot gas header 16 and this hot gas header connects the stills 17 with each of the retorts in these tiers to which the multiple standpipes 15 are connected. Three stills 17 are shown.

In each still is a roll 18 or other element of generally cylindrical contour. It is rotated at high speed on a horizontal axis by the motor 19, for example, at a speed of 900 to 1200 R. P. M. By rapid rotation of this roll, tar which is supplied to the still is sprayed in the form of a fine inlense spray up into the hot gases passing through the still. The tar is distilled and the gases are substantially detarred. The pitch produced is drawn off through the tar trap 19 and the levelling arm 20 into a trough 21. Here it is sprayed by a jet of cold water from the pipe 22. This chills and granulates the pitch and the solid pitch product is drawn off into the bin 23 Where it is separated from water in any desirable manner.

The hot gases and vapors pass from the stills through the settling towers or saturators 25. The tar fed to the still is supplied by the line 26 and sprayed into the tower through the nozzle 27. It

is partially distilled by the hot gases and vaporspassing through the tower or saturator and the distillation residue is drawn off from the bottom of the tower through the line 28 and fed to thestill 17 at the end of the still at which the hot gases enter from the header 16. Bailles 29 and 30 are provided in the saturator to remove entrained particles ofspray from the gases so that when cooled the gases which leave the tower will yield substantially clean oils. The standpipes l5, the hot gas headers 16, the stills 17 and the saturators 25 are advantageously heavily insulated as shown at 3l.

By closing part or all of the valves 35 connecting the retorts with the standpipes 7 and the hydraulic main and opening the valves 36 connecting these retorts with the standpipes 15, the coal distillation gases from these retorts will be passed into the stills and will be employed for the distillation of tar. The intense spray of tar in the stills scrubs the gases, the tar is distilled and the gases are enriched in oil vapors, and on cooling the gases leaving the stills, clean oil products are obtained. The flow of tar in the various stills may be independently regulated so that pitches of diierent melting points may be produced simultaneously. Separate condensers may be providcd for each still where this is desirable.

`According to the arrangement shown in Figs. 1 and 2 the gases and vapors from all of the stills are collected in the main 40 and pass into the heat interchanger 41 where they are brought intoy indirect contact with the incoming tar. The incoming tar is fed through the line 42 and after leaving the preheater a portion of the preheated tar is supplied to each of the stills. Heavy clean oils are condensed from the gases in the preheater and these oils are collected in the tank 43 and represent a high boiling oil fraction which may be disposed of as creosote oil.

After leaving the preheater the gases pass to the condenser 43' where they are sprayed with Water or ammonia liquor from the pipes 44. The condensate together with ammonia liquor is collected in the decanter 45 and the ammonia liquor and oils are separately collected in the tanks 46 and 47. An exhauster 48 is provided beyond this condenser to draw the gases through the system. This exhauster may be the same exhauster as that employed for drawing the gases from thehydraulic main through the condensers 10 and the same system for the recovery of ammonia and light oils, etc. may be utilized for treating both gases or separate systems may be provided. Valves 49 such as the ordinary butterfly valves may be provided for regulating the flow of gases through each of the stills.

Figs. 6 and 7 show a series of stills in combination with a gas retort plant and means for passing the tar through the stills in series. The stills \17a may each be connected with a number of retorts 6a. through the headers 16a and the standpipes 15a.. Each standpipe is connected with all of the retorts in a single tier. A spray of tar may be produced in each still by a roll 18a in the way described in connection with Figs. 1 and 2 and the pitch produced will be drawn 01T through the levelling arm 20a. The position of this levelling arm controls the depth to which pitch is retained in each still and consequently controls the nature of the tar spray thrown from the roll in each still.

According to the arrangement shown in Figs. 6 and 7, each of the stills is connected with a h ot gas and vapor main 50 and one settling tower or saturator 51 is provided for all of the stills. The gases and vapors are sprayed in this saturator with tar supplied through the line 52. Distillation residue from the bottom of the saturator is fed to the still through the line 53. This tar flows through the still countercurrent to the ow of the hot gases which are admitted to the still from the hot gas header 16a. The partially distilled tar or semi-pitch produced is drawn ofi into the cup 55 at the same end of the still as that at which the hot gases enter. A portion of this partially distilled tar may be'draw'n off through the line 56 to a separate storage tank to be used for road-treating purposes or in any other desired way. A portion of the tar from this cup 55 is supplied by gravity through the line 57 to the second still of the series. In the drawings it is shown as passing through the still in a direction countercurrent to the liow of the hot gases. After further distillation in the still itis drawn oil' into the cup 58. A portion of the semi-pitch produced may be drawn off to a separate storage tank through the line 59.

The last still of the series is supplied by gravity through the line 60 and where high melting point pitch is to be produced the semi-pitch from the preceding partial distillations is advantageously added to this last still at the same end of the still at which the hot gases enter, so that the hot gases and the pitch will flow through the still in a concurrent direction. The high melting point pitch produced is drawn off through the levellirg arm 20a into the trough 6l where is is met-with a spray of cold water from the line 62. This chills and granulates the pitch and the solid pitch lproduct is collected in the bin 63. l

After leaving the hot gas saturator the clean gases and vapors pass through the heat interchanger 64 where they are brought into indirect contact with the incoming tar. This tar is fed through the line 65 and after being preheated in the heat interchanger 64 passes through the line lui) n ammonia liquor and oils are separately collected in the tanks 70 and 71.

An exhauster 72 is provided for drawing the gases through the system and valves 73 are provided for regulating thetlow of gases through each of the stills.

Various modifications of the invention may be employed and existing gas retort y.plants mayf readily be equipped with means for employing the invention without extensive alterations. By proper manipulation high oil yields may be obtained and oils substantially free from tarry and pitchy ingredients may be produced directly.

References to pitch melting points referto melting points determined bythe method described in Methods of Analysis used in the Coal Tar Industry, by J. M. Weiss in the Journal of Industrial and Engineering Chemistry, vol. 10, No. 10, October 1918, page 817. Boiling points refer to boiling points determined by method D-246- of the American Society for Testing Materials.

This application is in part -a continuation of my copending application, Serial No. 326,770, filed December 18, 1928. f

I claim:

1.The method of distilling tar by direct contact with hot coal distillation gases from a bench of gas retorts which comprises collecting the hot gases to be used for the distillationfrom a plurality of retorts and combining them, passing the combined gases into a still at a temperature not greatly below that at which they leavel the retorts, intensely spraying tar to be distilled into the hot gases, so regulating the amount of tar supplied and the intensity of spraying with respect to the volume and temperature of the hot gases employed for distillation that almost instantaneous cooling of the gases to a substantially lower temperature, and rapid heating and distillation of the tar are effected, withdrawing distillation residue from the still, and withdrawing the mixed gases and vapors therefrom and cooling them to condense oils.

2. The method of distilling tar to pitch by direct contact with hot coal distillation gases from a bench .of gas retorts which comprises collecting the hot gases to be used for the distillation from a plurality of retorts and` combining them, passing the combined gases into a still at a temperature not greatly below that at which they leave the retorts, spraying tar into the gases Cin the still in the form of a iine intense spray which substantially iills the entire vvapor space of the still and washes the walls of the still `so that accumulation of pitch thereon is prevented, whereby the tar is rapidly distilled to pitch, withdrawing the pitch from the still, and withdrawing the mixed gases and vapors therefrom and cooling them to condense oilvapors.

3. The method of distilling tar by direct contact with hot coal distillation gases from a bench of gas retorts in which the retorts are arranged creased, combining the gases and vapors resultin tiers, which comprises collecting the gases from a plurality of the retorts in a plurality of the tiers and forming them into a plurality of hot gas streams, all while minimizing any drop in the temperature of the gases, introducing each of said streams into a different tar still, bringing tar into direct contact with each stream in each still whereby the tar is distilled and the vapor content of the gases is increased, and combining the gases resulting from the distillation of tar in the stills and also cooling the gases from the stills so as to recover distillate oils.

4. The method of distilling tar by direct contact with hotcoal distillation gases from a bench of gas retorts in which the retorts are arranged in tiers, which comprises collecting the gases from a plurality of the retorts in a plurality of the tiers and forming them into a plurality of gas streams all while minimizing any drop in the temperature of the gases, introducing each of said gas streams into a tar still, passing the tar through the stills in series, bringing the tar into direct contact with each of the gas streams in each of the stills and subjecting it to partial distillation in each of thek stills whereby the tar is progressively distilled and the oil vapor content of each gas stream is increased as it passes through the still.

5. The method of distilling tar by direct contact with hot coal distillation gases from a bench of gas retorts in which the retorts are arranged in tiers, which comprises collecting the gases from a plurality of the retorts in a plurality of the tiers and forming them into-a plurality of hot gas streams, all while minimizing any drop in the temperature of the gases, introducing each of said 1 gas streams into a diiferent tar still, bringing tar into direct contact with the stream of hot gas passing through each still, whereby the tar is distilled and the oil vapor content of the gas is ining from the distillation of tar in a plurality of the stills and bringing the combined gases and vapors into indirect heat interchanging relation with the tar to be distilled, whereby the tar is preheated and oils are condensed from the gases.

6. The method of distilling tar with highly heated tar-laden gases resulting from the distillation of coal in a gas retort which comprises repeatedly and continuously and thoroughly spraying the gases with such an intensive spray of the tar that the tar particles suspended in the gases are effectively removed so that on subsequent cooling substantially clean oils are obtained while simultaneously the tar is rapidly heated and distilled v and the gases are almost linstantly cooled to a 1 temperature approaching that to which the hydrocarbon is heated, separating entrained spray from the resulting gases and vapors, and cooling the gases and vapors to condense hydrocarbons therefrom in the form of clean oils.

7. In combination with a gas retort bench in which the retorts are arranged in tiers, an insulated standpipe connected to retorts of one of said tiers, a tar still adapted to contain a small body of tar, a hot gas header for conveying hot fresh 1

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