US1958584A - Distillation of tar - Google Patents

Description

- May 1934' s. P. MILLER 1,95 5

DISTILLATION OF TAR v Original Filed Dec. 29, 1928 3 Sheets-Sheet 1 I INVENTQR MM 7M$MMY ZI ATTORNEYS y 15, 1934- s. P. MILLER 1,958,584

DISTILLATION OF TAR Original Filed Dec. 29, 1928 5 Sheets-Sheet 2 ATTORNEY5 1 1934- s. P. MILLER Y 1,958,584

DISTILLATION OF TAR Original Filed Dec. 29, 19.28 3 Sheets-Sheet 3 Y ATTORNEYfi Patented May 15, 1934 DISTILLATION F TAR Stuart Parmelee Miller, Scarsdale, N. Y., assignor to The Barrett Company, New York, N. Y.,

corporation of New Jersey Application December 29, 1928, Serial No. 329,198 Renewed March 7, 1934 15 Claims.

This invention relates to improvements in the distillation of tar and the production of pitch. It includes a new method of tar distillation and pitch production and an improved apparatus therefor.

GMore particularly, the invention relates to improvements in the distillation of coal tar and the production of pitch at a coke oven battery.

In the ordinary operation of by-product coke ovens the gases produced by the coking operation passfrom individual ovens through individual uptake pipes and goose-necks to a collector main common to a battery of ovens. The coke oven gases leaving the ovens at a high temperature are cooled to separate tar constituents therefrom, the tar constituents being separated partly in the collector mains and partly in subsequent condensers.

Coal tar produced at by-product coke ovens is commonly shipped or conveyed to tar distillation plants where it is subjected to distillation for the recovery of coal tar distillates and the production of pitch as a residue of the distillation.

The present invention enables the tar to be distilled and pitch produced directly at a coal distillation plant without the need of a. separate tar distillation plant and without transportation expense.

According to the present invention, the hot coal distillation gases, as for example hot coke oven gases, as they come from the individual coke ovens, etc., are utilized 'for the distillation of tar and the production of pitch therefrom by bringing the tar into intimate contact with the hot gases immediately after they leave the coke oven. By bringing the tar directly into the hot coke oven gases at a high temperature, the tar is effectively distilled with separation therefrom of a greater or less amount of volatile oils, leaving a heavier tar or pitch as the product of the distillation. In 40 carrying out the present invention, the tar is brought into direct contact with the hot .coal distillation gases and is distilled to pitch, but the tar and pitch are protected from the high temperatures pertaining in close proximity to the uptake pipes adjacent to the ovens in order to prevent over-distillation or coking of such tar or pitch as might result from subjecting it to the intense heat radiated from these uptake pipes.

In the practice of the invention, several ovens of a coke oven battery may be connected with distilling means for converting tar to pitch, and the balance of the ovens may be connected in the usual way with a collector main and ordinary by-product recovery apparatus. As an alternative and preferred method of operation, all of the ovens of the battery may be connected with a collector main in the usual manner, and selected ovens of the battery may be equipped with additional uptake pipes, preferably located at the rear of the battery, and these uptake pipes will be connected with the tar distilling means of this invention. By the propermanipulation of valves in these additional uptake pipes and in the usual uptake pipes of these ovens which are connected with the ordinary collector main, the gases from these ovens may be directed into the ordinary collector main or they may be diverted into the tar distilling means.

In order to protect the product of the distil-' lation effected by the hot coal distillation gases, according. to this invention, from the intensive heat radiated from the uptake pipes, the stills are so constructed that the pitch collecting means located at the bottom of the stills is protected from this heat, as by locating this pitch collecting means at some little distance from the uptake pipes. The pitch is thus protected from localized overheating by the radiant heat from these uptake pipes. The uptake pipes by which the ovens are connected to the distillation means of this invention may be uptake pipes of the ordinary type from which goose-necks resembling the ordinary goose-necks conduct the hot gases to the still or into a pitch receiver located at the bottom of the still. Each individual still may be equipped with an individual pitch receiver or several stills may be equipped with a common pitch receiver.

The hot gases enter the bottom of the distilling means which may be an ordinary spray tower equipped at the top with a tar spray and at the bottoin with means for. admitting the hot gases and means for withdrawing the pitch. Where more than one still is employed, the gases leaving the tops ofthe stills enriched in volatile constituents are advantageously collected in a common collector main and conveyed from there to condensers.

The gases leaving the coke ovens carry en trained solid and liquid particles commonly known as tarfog.

Although a portion of these entrained particles may be removed from the gases in the still, due to contact with. the tar spray, where clean oils are desired the gases leaving the stills and collected in the gas collector main are advantageously passed through an electrical precipitator or other gas cleaning means a to remove entrained particles. 0n cooling the cleaned gases, clean oils are obtained directly from the gases.

By the enrichment constituents by distillation of tar in per cent of solid and liquid impurities carried by the gases based on the vapor content is reduced. This, together with the fact that some entrained particles may be scrubbed from the gases during the distillation, permits the production of cleaner oils than ordinary by this process.

The enriched gases whether passed through cleaning apparatus or cooled without cleaning may be cooled fractionally to produce fractional of the gases in condensible condensates or a total condensate may be obtained by cooling in a single condenser.

The melting point of the pitch produced by the distillation of the tar by the hot gases will depend upon the temperature to which the-tar is preheated before it is sprayed into the gases, the temperature of the gases, the amount of tar sprayed into the gases, the size of the tar particles, and the time during which the tar remains in contact with the hot gases. Where one passage of the tar through the still is not suflicient to produce a pitch of the melting point desired, the pitch produced may be recirculated through the still so that a higher melting point pitch is obtained and by regulating the proportion of fresh tar admitted to the still and the proportion of pitch recirculated, the melting point of the final product can be controlled. The distillation can further be regulated by admitting a small amount of water or ammonia liquor with the fresh tar in order to cool the gases and lessen the distillation of the tar.

Where a common pitch collector is provided at the bottom of several stills, an apron is advantageously provided at the bottom of each still to prevent gases from the uptake pipes which enter the bottom of the still from passing into the common pitch draw-oil.

In the drawings, various types of stills are shown. It is to be understood, however, that the invention is not limited to the illustrations given in the drawings.

In the drawings,

Fig. 1 is a plan view of a coke oven battery equipped with distillation means of this inven-' tion;

Fig, 2 is an elevation of the distillation means shown in Fig. 1;

Fig. 3 is'a sectional viewshowing the distillation means in its relation to the pitch collector main and the main for the enriched gases;

Figs. 4 and 5 are a plan view and elevation of a modified type of apparatus; and

Figs. 6 and '7 are elevations of other modified types of apparatus.

In the drawings, 5 indicates a coke oven battery equipped in the usual way with uptake pipes 6, a collector main '7, a center box 8, and crossover main 9, which may be of the usual type and are, therefore, shown schematically.

At the rear of the coke oven battery selected ovens are connected through uptake pipes 10 to stills 11 and by proper manipulation of valves in the uptake pipes 10 and the uptake pipes 6 the gasesfrom the selected ovens may be passed through the stills or to the usual collector main.

The stills may be ordinary spray columns equipped with spray means 12 .at the top and connected at the bottom with a hot' pitch main 13 which collects the pitch resulting from the distillation in the various stills. The gases pass from the ovens through the uptake pipes 10 into the bottom of the stills and in passing up through the stills pass counter-current to the spray of tar the still, the

admitted through the sprays 12. The tar is distilled and the pitch produced is drawn off the bottom of the stills through the aprons 14 into the pitch main 13. The apron 14 seals the bottom of each still so that the gases from each uptake pipe pass up through the corresponding still 11 and do not pass out into the pitch main. By withdrawing the pitch through the pipe 14' a constant level of pitch may be readily maintained within the main. The stills are provided with rodding holes 15.

The pitch is drawn off from the hot pitch main through the pipe 16 into the pitch container 1'1. Where one passage of the tar through the still does not produce the desired distillation of the tar, the partially distilled tar drawn ofi from the stills through the main 13 and pipe 16 into the receiver 17 may be in part recirculated through the stills by the pump 18 and line 19 and blended with fresh tar admitted to the system through the pipe 20. The recirculated tar and fresh tar are then sprayed into the still, and the proportion of recirculated tar and fresh tar is regulated in order to produce the desired distillation 'in the still. The finished pitch may be withdrawn from the tank 1'? through the draw-off 21.

The hot gases enriched in condensible constituents volatilized from the tar in the still are collected in the gas collector main 22. If clean oil productsare desired from the operation, the hot gases are passed through the gas collector main to suitable gas cleaning equipment such asan electrical precipitator. and the gases passing through the main 22 are maintained. at a willciently high temperature to ensure the passage of desired oil constituents through the main 22 and the cleaning apparatus in vapor form, so that they are carried as vapors over into the condensers where they are condensed by cooling in the usual manner. To maintain the gases at a high temperature the main 22, as well as the still, etc., are advantageously well insulated.

Where cleaning is not necessary and the oils are to be recovered as tarry oils, the gases may be cooled in the main 22 as with water or ammonia liquor sprays. A pipe 23 is shown at one end of the main 22 for flushing the bottom of the main with a suitable medium to prevent the accumulation or pitchy materials, etc., within the main where such flushing is desirable.

Although other spray means may be employed such as a scrubber, etc., in the drawings an electrical precipitator 24 is shown for cleaning the gases. The precipitator may be 01 the wellknown Cottrell type. By subjecting the gases to a silent electrical discharge as they pass through the precipitator, entrained solid and liquid particles are thrown out of the gases and collect in the bottom 01' the precipitator. They constitute a pitch of higher or lower melting point, depend- 130 cross-over main 9. Beyond the exhauster the 4 gases are treated for the recovery of ammonia, light oils, etc. In the condensers, the oils carried by the gases in vapor form as they leave the precipitator are reduced to the liquid state and are recovered as clean oils and drawn oil into the 1m receivers 40. Where the gases are cooled below the dew point of the gases for ammonia liquor, the receivers 40 will be operated as decanters for the separation of the ammonia liquor from the clean oils.

Figs. 4 and 5 show modified apparatus in which the pitch from each still 51 is separately collected in a separate receiver 50 instead of being drawn off into a common pitch main. The pitch from each still may be drawn oif into a common storage tank 52, or separate pitch storage tanks may be provided for the various stills. distillation is not attained in one passage of the tar through the still, the pitch may be recirculated from the pitch receiver 52 by means of the pump 53 and the line 54. Fresh tar is admitted through the pipe 55. By properly adjusting the ratio of the fresh tar and the partially distilled tar, the distillation can be regulated to produce a desired pitch, which may be drawn oil from the pitch receiver through the draw-off 56. A clean out hole 57 is shown for keeping the up-take pipe and goose-neck free from heavy pitch and coke.

As an alternative arrangement, a small amount of water or ammonialiquor may be sprayed into the gases through 59 to regulate the temperature of the gases employed in distilling the tar sprayed into the gases at 58. The gases passing up through the lower portion of the still 60 after passing from the ovens through the uptake pipes 10 on coming in contact with the tar sprays will distil the tar, and larger particles of spray entrained in the gases will settle out as the gases pass up through the settling chamber 61. The gases, more or less freed from entrained tar particles, then pass over into the gas collecting main. Pitch residue is collected in the receiver 62 which may be a receiver for the individual still or a common pitch main.

The arrangement shown in Fig. 7 is a somewhat modified form in which the gases pass through the uptake pipe 10 into the still 65, where they meet a spray of tar from the pipe 66. The temperature of the gases may be somewhat regulated by spraying a small amount of water or ammonia liquor into the gases from the spray nozzle 67. Vaporization of this spray cools the gases, and by regulating the spray the temperature of the gases with which the tar comes into contact may be more or less controlled. The pitch re-- sulting from the distillation of the tar by contact with the hot gases collects in the pitch receiver 68. This receiver may be an individual receiver for the one still or may be av tar main connected with several stills. Where the distillation of tar is not complete by one passage through the still, the partially distilled tar may advantageously be 'resprayed into the hot gases. By continually drawing oil a portion of the pitch and continuously adding a limited amount of fresh tar to the cycle, a pitch of desired melting point may be produced, and by regulating the temperature of the gases by admitting a fine spray of aqueous liquor through the spray nozzle 6'7, the degree of the distillation may be limited and controlled and excessive coking of the pitch may be prevented.

The various arrangements shown provide means for bringing tar into contact with fresh hot coal distillation gases and converting the tar into pitch. The tar is brought into contact with the fresh hot gases almost immediately after the gases leave the ovens. The tar is sprayed into the gases and passes counter-current to the hot gases and is distilled, the distillation residue be- Where complete 1 ing collected at the bottom of the still in a reservoir protected from the intensive heat radiating from the uptake pipe whereby excessive distillation of the pitch or decomposition of the pitch to produce coke is prevented. Although the in vention has been described more particularly as applied to the operation of a coke oven battery, other coal distillation gases may be employed in carrying out the invention, as for example the fresh hot gases from vertical gas retorts, etc.

I claim:

1. The method of distilling coal tar by hot coke oven gases and producing pitch therefrom which comprises spraying a regulated quantity of the tar into fresh hot coke oven gases immediately after leaving the oven, thereby distilling the tar by contact with the hot gases and producing pitch therefrom, and collecting the pitch resulting from the distillation in a body out of indirect heat interchanging relation with the stream of the hot gases thru the medium of the pipes conveying the gases directly from the ovens.

2. The method of distilling coal tar by hot coke oven gases and producing pitch therefrom which comprises spraying a regulated quantity of tar into fresh hot coke oven gases immediately after they leave the ovens, thereby distilling the tar by contact with the hot gases and producing pitch therefrom, and collecting the pitch resulting from the distillation at a point removed sufliciently from proximity to the uptake pipes of the ovens to prevent localized overheating of the pitch by the radiant heat from the uptake pipes to a temperature sufficient to cause objectionable decomposition of the pitch conveying the hot gases from'the ovens to the still.

3. The method of distilling tar and producing pitch therefrom which comprises conveying fresh hot coke oven gases directly from a coke oven into a still, passing the gases up through the still, spraying coal tar down through the still whereby the tar is distilled by the fresh hot gases and pitch is produced, spraying the walls of the still with tar to prevent the accumulation of pitch thereon, collecting the pitch from the walls and spray deposited directly from the gases in a body out of indirect heat interchanging relation with the stream of the hot gases thru the medium of the pipes conveying the gases out of the coke ovens.

4. The method of distilling coal tar to produce pitch which comprises conveying fresh hot coke oven gases directly from a coke oven into a still, passing the gases up through the still, spraying the tar into the gases as they pass up through the still, reducing the rate of flow of the gases to allow tar or pitch spray to settle from the gases, collecting pitch resulting from the distillation of the tar by contact of the tar spray with the hot gases, and cooling the gases leaving the still to recover condensable oil constituents therefrom.

5. The method of distilling coal tar with hot coke oven gases to produce pitch therefrom which comprises conveying fresh hot coke oven gases directly from a coke oven into a still, passing the gases up through the still, spraying the tar into the still and causing the tar to be distilled by contact with the fresh hot gases, collecting partially distilled tar at the bottom of the still at a distance sufficient to prevent undesirable decomposition due to localized overheating of the partially distilled tar by the radiant heat from the pipes conveying the gases from the ovens, and recirculating'a portion of the partially distilled tar through the still whereby it is subjected to fur- !-v ther distillation by the fresh hot gases and pitch is produced.

6. The method oiidistilling coal tar by hot coke oven gases which comprises conveying the fresh hot gases directly from a c 'ke oven into a tower still, passing the gases. up through the tower still, spraying the gases with'a limited amount or an aqueous solution in the still and then spraying them with the tar in the still whereby the tar is distilled, and collecting distillation residue at the bottom of the still.

'7. In combination with a coke oven battery, a tar still, an uptake pipe on top of one of the ovens of the battery and directly-Q connecting the oven with the tar still, a spray device for dispersing tar through thegases in the still, and a pitch receiver at the bottom of the still protected from undesirable radiation of heat from the uptake pipe.

8. In combination with a coke oven battery, a tower still, a tar spray in the top of the still and arranged to disperse a spray of tar through the gases in the still, an uptake pipe on top of one of the ovens of the battery and directly connecting the oven with the bottom of the still, a pitch receiver, and an apron at the bottom of the still dipping into the pitch receiver and thereby sealing the gases in the still against escape into the pitch receiver, the pitch receiver being situated at a distance 'from the uptake pipe of the coke oven.

9. In combination with a coke oven battery, several tower stills, means at the top of each still for spraying tar into each of the respective stills, means for separately conveying gases from individual ovens directly to the respective stills, a common pitch main at the bottom of the stills, a common gas collector main for receiving from the stills the gases enriched in condensable constituents vaporized from the tar, and aprons on the bottom oi! each still to seal each still in the pitch flowing through the pitch draw-ofl.

10. In combination with a coke oven battery, a tower still, a spray device at the top of the still arranged to disperse a spray of tar through the gases in the still, an uptake pipe on top of one of the ovens of the battery and directly connecting the still with the oven and constructed so that no great temperature drop takes place in coke oven gases during their passage therethrough, a pitch receiver at the bottom of the still at a sufficient distance from the place where said gas conveying means connects with the oven to prevent localized overheating of said pitch receiver by the radiant heat from said coke oven. 1

11. The method of distilling coal tar to produce pitch, which comprises separately conveying fresh hot coke oven gases from several ovens to several stills, passing the gases up thru the stills and spraying the tar down thru the stills whereby the tar is distilled by the hot gases and converted to pitch, collecting the pitch from the several stills in a common pitch main out of indirect heat interchanging relation with the stream of the hot gases passing from the ovens to the stills while keeping the gases from the'several ovens distinct and then collecting the gases from the various stills enriched in condensable oil constituents vaporized from the tar.

12. In combination with a coke oven battery a tower still, means at the top of the still arranged to disperse tar through the gases passing up thru the still and arranged to spray tar on to the walls of the still, an uptake pipe on top of one of the ovens of thebattery and directly connecting the oven with the still, a pitch receiver at the bottom of the still to collect spray which settles directly outof the gases into the receiver and to collect tar which drains from the walls of the still directly into the receiver, said receiver being at a sumcient distance from the place where said gas conveying means enters the oven to prevent localized overheating of the receiver by the radiant heat from the gas conveying means.

13. In combination with a coke oven battery a tower still, means at the top of the still for spraying tar into the still, a pitch receiver at the bottom of the still and an uptake pipe on top of one of the ovens of the battery and directly connecting the oven with the top of the receiver.

14. In combination with a coke oven battery a tower still, means at the top of the still for spraying tar into the still, a pitch receiver at the bottom of the still and an uptake pipe on top of one of the ovens of the battery and directly connecting the oven with the still near but not at the bottom thereof.

15. The method of distilling coal tar and producing pitch therefrom, which comprises spraying a regulated quantity of the tar into fresh hot coke oven gases immediately after they leave the oven, thereby distilling the tar by contact with the hot gases and producing pitch therefrom, passing the resultant mixture of gases and oil vapors through a settling zone whereby entrained particles of liquid are separated from the gases, collecting the pitch resulting from the distillation in a body out of indirect heat interchanging relation with the'stream of hot gases through the medium of the pipe conveying the gases directly from the ovens, then cooling the gases to recover condensable oils.

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