US1898980A - Distillation of tar - Google Patents

Description

Feb. 21, 1933, s. P. MILLER DISTILLATION OF TAR s sneexsa-she'et 1 and Nov. 2, 192a ATTORNEYS Feb 21; 1933. s. P. MILLER 1,898,,98G

' msfinunou or rm Filed Nov. 2. 1928 3 sheets sheet 2 INVENTOR BY be AW;

Feb. '21, 1933. s. P. MILLER 1,898,980-

mSuLmnou or my Filed Nov. 2. 1928 s snooty-Sheet 3 INVENTOR AT TORNEY6 rammed Feb. 21, 1933 UNITED sa'ras STUART PABMELEE HILLEB, 0F ENGLEWOOID, NEW JERSEY, ASSIGNOR TO THE B a.

COMPANY, {OF NEW YORK, N. Y CORPORATION OF NEW EY nrsmm'rronor' TAB Application filed Rovember 2, 1928. Serial E0. 318,886.

battery. The foul gases leave the ovens at high temperature, e. g., 600 to 700 C. or higher and carry a considerable proportion of volatilized tars and oils as well as solid particles of coke, coal, carbon and other impurities such as entrained pitch, tar fog, etc. Or-

dinarily the gases are cooled as rapidly aspossible by the application of sprays of ammonia liquor or ammonia liquor and tar of tar alone in the goose-necks and collector main, the heat in the gases being thereby (118' sipated and lost. The rapid cooling causes tion of tar constituents.

separation of tar containing heavier oils in the collector main. Further cooling is effected in the cross-over main and in the con densing system connected thereto for the purpose of separating heavier and lighter oils from the gases. These oils are contaminated ordinarily with a considerable propor- The collected tar and oils are usually shipped from the cokeoven plant to a tar-distillation. plant for distillation and separation of the oils and the production of pitches of varying qualities. The expense of handling and of distilling the tar adds to the cost of production of the distillation products. I

It is the object of the present invention to use the heat carried by hot coal-distillation gases to distill tar and produce pitch there from, and to forcibly inject the tar into the gases and thereby cause removal of entrained liquid or pitchy particles and solid particles,

- such as bits of coke, from the gases. By suitable regulation of the process, coal tar solution, creosote oil or clean tar acid oils or other lighter oils can be directly produced from the treated gases by cooling.

According to this invention the tar is brought into contact with the gases while the gases are at a sufficiently high temperature to distill desired oils from the tar and to retain these oils in vapor form while they pass 5 thru the injector and thence into the condensers. The injector is of the type in which a liquid is sprayed under pressure into a gas in a restricted passage or nozzle in such a way as to thoroughly mingle with the gas and to 1 draw the gas thru the passage. The tar is sprayed into the gases with such force and such an intimate degree of contact with the gases is attained that the entrained impurities are effectively removed from the gases.

The force with which the tar is injected. into the gas affects the size of the individual droplets of tar, and the intimacy of contact with the gases and hence afl'ects the rate and degree of distillation of the tar by the hot gases;

the finer the particles of tar and the more intimate the contact between tar and gases, the more effectively will the heat of the gases be utilized for distilling the tar.

According to the present invention the heat of the coal-distillation gases as "the latter come from the coke ovens is utilized to distill tar and to separate vaporizable oils therefrom by aspirating the hot gases with a jet or jets of tar or oil or mixtures thereof. The 89 gases are thus intimately mingled with the tar or other scrubbing medium and the scrubbing of the gases efi'ected thereby causes the separation therefrom of substantially all liquid and solid particles, leaving the gases substantially free from liquid tarry and solid constituents. The result is easily attainable by conducting the scrubbing operation at a sufficiently high temperature. The, dew

points of the gases for the several constit- 90 uents carried therein as vapor are lower than the normal boiling points of these constituents and by suitable regulation of the tem: perature of the gases it is possible to separate at temperatures considerably below the normal boiling point of the oils all or substantially all of the unvolatilized tarry or pitchy constituents while the oils remain in the vapor phase. By cooling the gases to a suitable point the tarry constituents are converted into the liquid hase in which they are readily removed by t e scrubbing operation. The

tar or oil employed as a scrubbing medium I is at the same time subjected to the distilling effect of the hot gases and the latter are enriched in volatile oil constituents while the tar is converted into pitch. By regulating the operation the amount of heating to which the tar is subjected may be varied to produce a pitch having the desired characteristics and pitches having a melting point of around 200 F. or even as high as 250 F. or 300 F. or higher, can be secured by the distillation either directly or by recirculation of the tar or pitch through the same or other injectors in which it is repeatedly subjected to the effect of the hot coal-distillation gases.

The operation can be conducted in various ways and in different types of apparatus. It can be applied readily to an ordinary cokeoven plant in which the ovens of the battery are connected by the usual goose-necks to a collector main from which some or all of the gases if desired may be delivered through a cross-over main to an ordinary condensing system. The gases may be cooled or partially cooled in the collector main by sprays of ammonia liquor or ammonia liquor and tar or tar supplied thereto through suitable s ray nozzles. The tar and ammonia liquor t rown down in the collector main can be withdrawn and separated and the tar can be subjected subsequently to distillation-in the manner hereinafter described. Further cooling can be effected in the condensers to separate tarry oils and these likewise may be subjected to distillation. In applying the resent invention to such an apparatus an injector can be connected to one end of the collector main, the cooling sprays being pref erably eliminated at that end of the main and the hot gases can be withdrawn from the main through the injector by forcing tar into and through the injector so that a suction effect is created which not only withdraws the gases from the collector main but causes them to mingle intimately with the tar in the injector. Preferably the injector is disposed in a suitable chamber and is directed downwardly therein so that the tar and hot gases travel together in a downward direction. the resulting pitch being accumulated in the bottom of the chamber from which it can be withdrawn either continuously or otherwise. The gases can likewise be withdrawn from the injector chamber and treated as hereinafter described for the recovery of the oil constituents.

All or any part of the hot gases may thus be caused to pass through the injector for intimate contact with the tar to be distilled and the coneurrmit scrubbing of the gases to remove tarry and solid constituents therc from.

One or more such injectors can be employed,

Thus, a number of injectors may be arranged in series so that the gases after traveling through one of the injectors are delivered to the next succeeding injector under the suction effect produced by the jet of tar supplied thereto. Or each of the injectors can be separately connected to the end of the collector main so that it will withdraw hot coal-distillation gases therefrom and utilize the heat thereof for the distillation of tar supplied to the injector. Instead of connecting the inj ectors to the collector main they may be connected directly to an uptake pipe or uptake pipes from selected ovens of the battery. An injector or injectors can be arranged, for example, at the rear of the ovens and gases can be supplied from the selected ovens while the gases'from other ovens of the battery are conveyed through the usual collector main and treated therein in the ordinary manner. It will be understood that in either case the quantity of gases required for the distillation of the amount of tar available is utilized for that purpose and that the remaining gases are treated in the ordinary manner for the separation of tar and tarry oils therefrom and that the tar and tarry oils thus recovered can be subjected to distillation by intimate.contact with the hot coal-distillation gases in the manner herein described.

The scrubbing medium employed in the injectors may be ordinary tar or oil or tar and oil or it may be pitch produced b a partial distillation of the tar. The scrub ing material may be introduced at ordinary temperatures or it may be preheated, partially dehydrated or partially distilled. In producing high melting point pitches it is desirable to preheat and partially dehydrate the tar and in some cases to effect an initial distillation thereof in order that the more readily vaporizable constituents may be removed before the tar is introduced to the injector or injectors for distillation in accordance with the present invention. It will be understood, however, that where a number of injectors are employed in series the tar or pitch produced in one of the injectors may be delivered to the second and thence to the third, for example, for further distillation and the preheating, dehydration and partial distillation may be effected thus in the initial injector and the distillation can be completed in the subsequent injectors.

The scrubbing of the gases and the distillation of the tar when the operation is conducted at relatively high temperatures, provides gases enriched in oil constituents which can be recovered subsequently by cooling the gases in suitable condensers. The cooling can be effected in a single condenser or in two or more conden ers. ln the til-st case a mixture of oil constituents including creosote oil and carbolic or tar-acid oil is obtained. The invention is well adapted for the production of oils rich in tar acids and such oils can be recovered separately by fractional condensation of the gases after the latter have been utilized for distillation of tar and scrubbed in the manner described to remove liquid and solid constituents therefrom. Thus, the gases can be cooled in a condenser to a temperature around 130 to 150 C. to separate creosote oil therefrom, and it may be cooled subsequently in a second condenser to a temperature of around 85 to 90 0., to recover light creosote oil and to 25 to 45 C. to recover carbolic oil, although in many cases the car bolic oil and light creosote oil will be collected in one fraction. The condensers employed may be either direct or indirect type. After separation of the light creosote oil at a temperature of from 85 to 90 C. the gases can be passed thru an ammonia saturator and then further cooled to around 25 C. to recover oarbolic oil.

Where total codensation or the separation of oil in a single fraction is desired it may likewise be advantageous to cool the gases to a temperature of about 85 to 100 C., i. e., above the dew-point of water, and then to pass the gases while still above the dew point of water through the ammonia saturator for the direct recovery of ammonia therefrom. The gases can then be cooled further to a temperature around 25 C. to separate additional quantities of lighter oil constituents. Alternatively the gases can be cooled to a temperature of from 25 to 35 0., to condense substantially all of the condensable oil constituents either in a single fraction or in two or more successive fractions and the gases may be passed then through an ammonia saturator to absorb the ammonia in sulphuric acid or to an ammonia absorber in which the ammonia is absorbed in water to form ammoniacal liquor.

The invention is of more or less general application to the distillation of tar to produce pitches and to recover oils and particularly clean oils from coal-distillation gases. The tar distilled may be from an outside source. VVater'gas tar or other types of tar may be distilled. The invention will be further illustrated by the following more detailed description taken with the accompanying drawings which showapparatus embodying the invention and adapted for the practice thereof, but it is intended and will be understood that the invention is not limited to the specific details of the apparatus illustrated in the drawings, in which Fig. 1 is a plan view of a portion of a cokeoven plant illustrating the application of the invention thereto:

Fig. 2 is an enlarged sectional view of the injector chamber: and

Fig. 3 is a plan view illustrating another application of the invention.

Fig. 4 shows still another application of the invention.

Referring to the drawings, 5 indicates a battery of coke ovens in which the individual ovens are connected by uptake pipes and goose-necks 6 to a collector main 7 having a centre-box 8 from which a cross-over main 9 conveys the gases and vapors to condensers 10 and 11. The gases may be cooled in the collector main and in the goose-necks leading thereto by ammonia liquor or ammonia liquor and tar introduced through spray nozzles 12 which are supplied thru a pipe 13 from a source of ammonia liquor such as a storage tank 14 Further cooling is effected in the condensers 10 and 11 and the gases are delivered thence to an exhauster 15 and to the usual equipment for the separation of light oils and ammonia from the gases. The tar which separates in the collector main 7 and cross-over main 9 may be withdrawn and delivered through a pipe 16 to a decanter 17 wherein the tar is separated from the ammonia liquor. The latter may be delivered through a pipe 18 to the storage tank 14. Tar and liquor from 10 and 11 pass to decanters 17 thru pipe 16. A total tar is thus collected from the decanter. The apparatus as described represents the usual coke-oven plant to which the invention may be applied.

To carry out the invention the plant is provided with one or more injector chambers 20 with injector nozzles 21 disposed preferably at the top of the chambers and connected by pipes 22 to the end of the collector main 7 so that hot coal-distillation gases can be withdrawn from the collector main under the effect of suction produced by the introduction of tar or oil or mixtures thereof under pressure'to the injector nozzles 21. The tar or oil employed as a scrubbing medium may be supplied through pipes 23 and 24 from any suitable source thereof. As hereinbefore in dicated, the cooling effected in the collector main adjacent to the end thereof from which the gas is withdrawn may be reduced and in general in the operation of the process the cooling effected in the collector main should be limited to avoid reducing the temperature of the gases before the latter are delivered to the injector or injectors. To accomplish the most effective distillation the temperature of the gases should be maintained at the highest practicable point, although lar er quantities of lower temperature gases \vi 1 likewise aecomplish distillation.

The pitch produced by distillation in the injectors may be removed from the injector chambers and recirculated by pumps 25 through pipes 26 either through the same injectors or through successive injectors supplied similarly with hot gases from the collector main. The residue may also he recirculated thru pump 25 and line 26'. Fig. 2. This permits the further distillation of the itch to increase the melting point thereof and to recover additional quantities of oil therefrom.

The gases after intimate contact and scrubbing with the tar or pitch are withdrawn through pipe 27 and delivered to the condensing system which may include condensers 27 and 28 of the direct or indirect type in which the gases may be further cooled to separate oil constituents. As hereinbefore indicated, the type of cooler employed and the temperature maintained therein will depend upon the nature of the product which is to be recovered. The separated oils may be withdrawn from the condensers through pipes 28 and 29 and delivered to separate decanters 30 and 31 and thence to separate storage not shown. The gases, after passing through the condensers, may be delivered thru a pipe 32 to an ammonia saturator or absorber 33 in which ammonia is recovered by absorption in sulphuric acid or the ammonia may be absorbed in water in absorption towers of the usual type, not shown. The gases may pass thence thru a pipe 33' to another condenser 34 in which light oils are separated and recovered.

In another application of the invention a single injector chamber 36 may be dis posed at the rear of the ovens and may be connected by elongated uptake pipes or thru a short collector main 37 to selected ovens of the battery. The injector chamber may be provided with a nozzle 38 which is supplied with tar or tar and oil under pressure thru pipe 39. The passage of the tar or other scrubbing medium thru the nozzle induces the movement of the hot coal-distillation gases thru the injector nozzle and thus mingles the tar intimately with the hot ases with the resulting scrubbing and distilling effect as hereinbefore described. The u take pipes may be insulated to avoid loss 0 heat therefrom and thus to permit introduction of the gases to the Injectors at substantially their maximum temperature. The pitch produced can be withdrawn from the injector chambers and utilized as such or returned for further distillation by means of a pump 40 and ipe 41 to the injector for the purpose of e ecting further distillation.

The gases containing oil vapors resulting from the distillation and substantially free from tarry constituents are delivered through pipe 42 to condensers 43 and 44, for example, arranged in series and supplied with cooling media for the purpose of separating the oil constituents from the gases. The oils may be withdrawn through pipes 44 and 45 and delivered to separate receptacles 46 and 47. The gases may pass from the condensers to an ammonia saturator or absorber 48 and thence to another condenser 49 for further cooling to separate light oil constituents or other arrangement of equipment may be used for recovery of ammonia or light oil.

Instead of utilizing only a portion of the gases from a battery according to the process of this invention, all of the gases may be so treated b apparatus such as that shown in Fig. 4. Vhereas the gases from the various ovens of the battery ordinarily pass from the collector main 7 thru the centerbox 8 to the cross-over main 53 and thence to coolers not shown by closing the valve 54 and o ening the valve 55 the gases may be passe from the collector main thru the center-box up thru the pipe 57 into and down throu the shell of the injector 59 to the cross-over main 53. According to the drawings tar from the center box of the collector main, after being separated from ammonia liquor in the decanter 60 is supplied to the nozzle 61 of the injector thru the pipe 62 by means of the pump 63. Other tar may be used. Several injectors may be provided in the cross-over main, in series, instead of the single injector shown. By regulatin the amount of spray liquor supplied to t e collector main in the usual way thru spray nozzles not shown, the temperature of the gases entering the injector may be controlled to some extent, and thus the extent to which the tar is distilled can be controlled. Other factors influencing the extent to which the distillation is carried are the height of the injector, the rate at which the tar is su plied to the injector, the temperature of t e tar entering the injector, etc.

It will be understood that the invention as described permits cleaning of the gases in a simple and effective manner so that clean oils can be obtained directly' from the coal-distillation apparatus and that, moreover, the quantity of oils recovered is increased materiallyhl ily the distillation of tar with the gases. oreover, the enrichment of the gases in oil constituents permits the more effective recovery thereof by simple condensation operations. The procedure and the apparatus as herein described may be modified and rearranged in various ways to accomplish the purpose set forth, and various changes may be made, therefore, in the details of application of the invention without departing therefrom or sacrificing any of the advantages hereinbefore set forth.

I claim:

1. The method of distilling ofl' volatile constituents from a material of the group consistin of tars, pitches, and oils by contact with ot fresh coal distillation gases which comprises introducing into a restricted passage the coal distillation gases at a temperature substantially above the dew point of the gases for such constituents, injecting into said passage said material in liquid phase and under pressure whereby a Zone of reduced pressure is maintained in the passage and thorough and intimate contact of the gas and liquid is obtained therein, and regulating the volume of liquid introduced with respect to the volume and temperature of the ingoing gases in such a. manner that the gases are cooled to a temperature above said dew point.

2. The method of distilling of volatile constituents from a material of the group consisting of tars, pitches, and oils by contact with hotfresh coal distillation gases which comprises introducing into a restricted passage the coal distillation gases at substantiall v their maximum temperature, injecting into the passage said material in liquid phase and under pressure whereby a zone of reduced pressure maintained in the passage and thorough and intimate contact of the gas and liquid is obtained therein, regulating the volume of liquid introduced with respect to the volume and temperature of the ingoing gases in such a manner that the gases are cooled to a temperature not less than the dew point of the ingoing gases for said constituents.

The method of distilling off volatile constituents from tar thereby forming pitch by contact with hot fresh coal distillation gases, which comprises introducing into a restricted passage the coal distillation gases at substantially their maximum temperature. injecting into the passage the tar to be distilled in liquid phase and under pressure whereby a Zone of reduced pressure is maintained in the passage and thorough and intimate contact of the gas and tar is obtained, and regulating the volume of tar introduced with respect to the volume and ten'iperature of the ingoing gases in such a manner that the gases are cooled to a temperature above the dew point of ingoing gases for the volatile constituents to be distilled oil".

4. The method of distilling tar by contact with hot coal distillation gases to obtain pitch and vapor-containing gases which, upon cooling, yield clean oils, which comprises introducing into a restricted passage hot coal distillation gases at a temperature substantially above the dew point of said gases for said vapors, injecting into said passage said tar in liquid phase and under pressure whereby a Zone of reduced pressure is maintained in the passage and thorough and intimate contact .of the gas and taris obtained, regulating the volume of tar introduced with respect to the volume and temperature of the incoming gases in such a manner that the ten'ipcrature of the gases is reduced to a temperature above said dew point, separating the gases from the residue, and cooling the gases to condense said vapors.

5. The method of distilling tar and forming pitch by means of hot fresh coal distillation gases, which comprises introducing into a restricted passage the coal distillation gases at substantially their maximum tent perature, injecting into the passage the to be distilled in liquid phase and under pressure whereby a zone of reduced pressure is maintained in the passage and thorough and intimate contact of the gases and tar is obtained, regulating the volume of tar introduced with respect to the volume and tempcrature of the ingoing gases in such a man nor that the gases are cooled to a temperature above the dew point of ingoing gases for the volatile constituents to be distilled off, and a pitch residue having a melting point of atleast 200 F. is obtained.

6. The method of distilling tar by contact with hot coal distillation gases to obtain pitch and vapor-containing gases, which, upon cooling yield clean oils, which method comprises introducing into a restricted passage hot coal distillation gases ata temps ature substantially above the dew point of the gases for said vapors, injecting into said passage said tar in liquid phase and under pressure whereby a zone of reduced pressure is maintained in the passage and thorougland intimate contact of the gases and tar is obtained, regulating the volume of tar introduced with respect to the volume and temperatnre of the ingoing gases in such a man" her that the ten'iperature of the gases is reduced to a temperature above said dew point, separating the gases from the residue, and iractionally cooling the gases to condense therefrom an oil suitable for use as carbolic oil.

'i". In the operation of a coke oven battery wherein the gases from a major portion of the ovens of the battery are cooled recover tar, the process for distilling of? volatile constituents from the tar, which comprises col-- lecting hot fresh coal distillation gases from a minor portion of the ovens of the battery and introducing them into a restricted passage at a temperature substantially above the dew point of the gases for such constituents, injecting said tar into said passage under pressure whereby a zone of reduced pressure is maintained in the passage and thorough and intimate contact of the gases and liquid is obtained therein, and regulating the volume of liquid introduced with respect to the volume and temperature of the ingoing gases in such a manner that the gases are cooled to a temperature above said dew point, and the tar is distilled to pitch.

In testimony whereof I attix my signature.

STUART PARMELEE MILLER.

Images