US1826430A - Recovery of creosote oils, tar acids, etc. - Google Patents

Description

' Oct. 6,1931. 5. MILLER 1,826,430

RECOVERY CREOSOTE OILS, TAR ACIDS. ETC

Filed July 16, 1927 2 sheets-sheet 1 ATTORNEYS Oct. 6, 1931. s. P. MILLER RECOVERY OF CREOSOTE OILS, TAR ACIDS, ETC

Filed July 16, 1927 2 Sheets-Sheet 2- I VENT (R W M M rm ATTORNEYS Patented Oct. 6, 1931 I uNrrEn STATES PATENT orrlcr.

STUART PARMELEE MILLER, OF GLEN RIDGE, NEW JERSEY, ASSIGNOB TO THE BARRETT COMPANY, OF NEW YORK, N. Y., A- CORPORATION OF NEW JERSEY' RECOVERY OF CREOSOTE OILS, TAR ACIDS, ETC.

Application filed m 16,

This invention relates to the recovery of commercially useful products directly from hot coal distillation gases, and particularly from coke oven gases. The products recovered include creosote oil and carbolic oil, as well as pitch of high melting point and low carbon content, ammonia, etc. The common method of producing creosote and carbolic oils is by distillation of'coal tar in ordinary tar stills. The lighter oils first distilled are the carbolic oils, while the higher boiling point distillate forms the creosote oils. The residue'of the distillation is a .pitch relatively high in carbon content, the distillation being accompanied by a very considerable decomposition of oil constituents of the tar, withresulting decrease in yield of oils distilled and increase in pitch residue and in carbon content of the pitch residue. The creosote and carbolic oils contain only such undecomposed constituents of the tar as distill without decomposition, together with such condensahle decomposition products as are of a volatile character at the temperatures of the distillation. When the distillation is carried H to high temperature for the obtaining of a large yield of creosote oil, the decomposition is particularly marked, and the relative increase in pitch residuea'nd carbon content thereof is correspondingly fgreater.

' Such distillation of tar or the production of creosote oil and carbolic oil is commonly carried out at tar distillation plants at a greater or less distance away from the coke oven plants where the tar is produced, requiring transportation of the tar from'the coke" oven plant to the tar distillation plant with attendant expenses and handling losses.

The present invention provides an improved process whereby the production of tar at the coke oven plant and its handling and shipment and subsequent distillation at a tar distillation plant are obviated, and whereby mized.

the expense and losses incident to handling and transportation are eliminated or mim- According to the present invention, creosote oil and ca-rbolic oil are directly produced at the coke oven plant from the. coke oven gases, in a marketable form, requiring no further 1927. Serial no. 206,367.

treatment, and there is simultaneously produced a pitch residue of low carbon content.

According to the present invention, the hot coal distillation gases from the ovens or retorts are subjected to a limited and regulated cooling to a lower but still high temperature, such that there is separated out and carried in suspension in the hot gases particles of pitch of high melting point, while leaving the greater part of the oils of the gases in vapor form. The gases so cooled to a regulated temperature are then subjected to a cleaning operation'for the removal of the pitch particles therefrom, leaving clean gases containing va ors of oil suit-- able for creosote oils and car olic oils. The cleaned gases are then subjected to further cooling in successive stages, first to a temperature around,'e. g., 85 to 100 C., and then to a low temperature, around 25 to 35 (3., and there is directly condensed and recovered therefrom a higher boiling creosote oil" and a carbolic oil, which oils contain constituents WhlCh do not readily boil and distill without decomposition, and which oils are in this and other respects distinguished cleaning treatment to remove itch particles therefrom at a suficiently hig temperature to leave carbolic or tar acid oils in vapor state, then cooling the cleaned gases to separate a tar acid oil therefrom and extracting the tar acids from such oils.

In my companion application Serial No. 206,366 Ihave set forth a process in which a creosote oil, is directly recovered from hot coal distillation gases by cleaning the gases at a high temperature to separate pitch particles theref om, then cooling the cleaned gases to a low temperature, around 25 to o '85 oils are directly recovered from hot coal d1s-. .tillation gases by Sub ecting the gases to a 35 C., to separate therefrom a creosote oil containing both high boiling and low boiling a temperature such that carbolic or tar acid.

constituents, blended together to form a balanced oil composition suitable for use directly for creosoting purposes.

' The improved process of the present-inhot coal distillation gases of .both a creosote oil and a carbolic or'tar acid oil by cleaning the hot gases at a sufliciently high temperatureto leave therein oils includingheavy v011s, and then subjecting the hot cleaned gases to cooling first to a temperature such that a creosote oil will be separated therefrom and subsequently to further cooling to oil will be separated therefrom.

The creosote oils produced in accordance with the present invention may, to a large extent,- be similar to the creosote oils produced in accordance with my companion ap-- plication Serial No. 206,366, butwill be substantially free from the lighter oil components, which are separately recovered as carbolic oils.

The cooling of the hot coke oven gases,

according to the present invention, is regulated and limited so that only the heavier the ovens, the heavierpitch constituents which are orlginally present in the form of vapors, are progressively condensed as the temperature is lowered, and they, together with any suspended particles of carbon, etc., will be removed from the gases by the cleaning operation. The initial cooling of the gases can be eifected by a limited spray or contact with water or ammonia liquor, or by regulated atmospheric cooling while the gases are passing through pipes or conduits exposed to the atmosphere. The gases can be collected in the ordinary collector mains and subjected therein to a regulated cooling, as by the limited introductlon of ammonia liquor into contact therewith. Such cooling by ammonia liquor may result 1n local overcooling of some of the gas and separation of heavy tar therefrom in the collector main, but the average temperature of the gases leaving the collector main can be maintained sufliciently high so that a relatively high melting point pitch can be separated therefrom when the gases are subjected to the cleaning treatment.

The cleaning of the gases at a re lated temperature can be effected by a su ciently intimate scrubbin with hot pitch; for example, hot pitch aving a temperature and composition the same as or similar to that of the pitch particles carried in suspension in vention provides for the recovery from the.

the gases. The cleaning is inore advantageously efl'ected, however, by an electrical pre cipitator through which the gases are passed and in which theyare subjected to the action of high tension electric current. The clean, in treatmentis'carried out without any co'nsi erable further reduction in temperature, so as to leave the gases escaping from the precipitator the desired heavy oils. v

The cooling of the cleaned gases from the high temperature of the cleaning operation to the lower temperature of around 25 to 35 C. is carried out in successive stages so that there is thus separated therefrom an oil suitable for use directly as a creosote oil, and so that there is subsequently separated from thegases a' lighter oil rich in phenols or tar acids, which oil forms a valuable carbolic oil. After the gases have been so cooled and the respective oil's removed therefrom,.they are then passed through anammoniaabsorber or saturator, for the recovery of ammonia, and then to a scrubber or-absorber for the recovery of light oils such as benzol.

The temperature to which the gases are cooled before they are subjected to the clean- 1 ing treatment, is a relatively high temperature, so that a large yield of oil vapors is retained therein, and so that a relatively high melting point pitch is obtained. The melting point of the pitch will increase or decrease as the temperature at which the v gases arecleanecl' is raised or lowered, and, the proper temperature of operation can be readily determined and regulated by the characterof the pitch produced, particularly as difl'erent coal distillation gases may .require different tem eratures for the preparation of pitch of t e same melting point.

With the direct production of a lower melting point pitch, for example, having a melting point around 145 F.,'the yield of creosote oil will be materially less than when a higher melting point pitch is directly recovered and an increased amount of heavy oils left as vapors in the cleaned gases. Even with the production of a melting pointof a itch at around 145 F., however, there can e produced a creosote oil, suitable for use d rectly for commercial purposes. Such an oil can be obtained, for example, in a yield representing around 10 to 20 percent of the .tar which would ordinarily be' recovered from the gases. In addition, there can be recovered from the gases a carbolic oil representing around 15 to 20 percent of the tar which would ordinarily be recovered from the gases. The creosote oil obtained when such a relatively low melting point pitch is produced Will be relatively free from the eavier oil constituents, but it will also be free, or relatively free, from the lighter car I higher melting point pitch residue, for example, a itch of meltlng point around 160 to 170 an increased yield of creosote oil can be directly'recovered from the gases, while a similar yield of carbolic oil can be subsequently recovered at a lower tempera ture; If the cleaning is carried out at a still higher temperature, to leave a pitch of, for

example, 200 F. or 300; F or even 400 F.

cases around 85 to 90 C., such that the oils desired in the carbolic oil product will be retained in vapor state in the gases leaving the creosote oil condenser, although it is not essential that a sharp fractionation or separation be obtained.

The. gases leaving the creosote oil condenser then pass to the carbolic oil condenser, where they are cooled to a low temperature, around to 0., to separate the carbolic oil therefrom. The gases then pass to the ammonia absorber or saturator for the recovery of ammonia, and then to the light oil I melting point,'the creosote oil recovered from absorption system.

The condensers for separating the creosote'oil and carbolic oil directly from the 15 the ases willbeahearier creosote oil, rich .111 high boiling andheav constituents, 1n-

' eluding constituents whic are normally of 3 oil shoul gases, be around 80 to 100 a grease or resin-like character, but which .in admixture with the other oil constituents blend therewith to form a homogeneous liquid.- These grease or resin-like constit uents form valuable components of-the creos'ot'e oil, 'since they remain as a residue in the creosoted material after the volatile oils have 25 :been to a large extent volatilized or va orized.

' e The creosote oilcomposition pr need in accordance with the present invention will have a relatively hi h initial boilingpoint. Instead of having a hailing point'such that a 9small percentage will be distilled at temperature up to 210 0., in general an appreci- 1 ably higher temperature will be requlred before'a'ny considerable amount of the oil will be vaporized although it is not essential that the be free from constituents such that when heated to tem eratures of 210 C. some distillation will ta e place. As comparedwith' the creosote oils produced in accordance with my companion application (Serial No. 206,366), the creosote oil pro- Y duced in accordance with the present process will, when it contains heavy constituents and is produced 'from gases rom which pitch of the same melting point has been se arated,

45 be a heavier creosote oil, being free rom the light carbolic oil constituents which are retained in the creosote oil composition pro .duced according to the process of; my said companion application. When the creosote oil produced according to the process of the present invention, is an intermediate oil, produced from gases from which a lower melting'point pitch has been separated, it will likewise be a somewhat heavier cresote oil in the sense that it will be free from or contain the coal distillation gases, but in general the coke oven temperature will, for ordinay or in some gases may be of'either the indirect'type,

cooled by indirect contact with the cooling medium, or direct condensers in which the cooling liquid is directly introduced into the hot-gases. If cooling liquid is introduced directly into the gases in the creosote oil condensers, the temperature of the liquid should be regulated so that local over-cooling is not obtained, and a large amount of the carbolic oil thrown down with the creosote oil, although some of the carbolic oil can be so thrown down and included in the creosote oil. The cooling of the gases in the-creosote oil condenser can advantageously be obtained by the introduction into the gases of some of the carbolic oil supplemented by external cooling, since the vaporization of the carbolic oil will tend to give a closer separation between the creosote and carbolic oil products.

The cooling of the gases in the carbolic oil condenser can advantageously be carried out with direct introduction of water or ammonia liquor, in which case the ammonia liquor is advantageously free from tar. so that a clean or tar-free ammonia liquor is directly obtained, from which the ammonia can be recovered without contaminating tar impurities. Even withindirect cooling of the gases in the carbolic oil condenser, there will'be condensed more or less water with the oils in the form of dilute ammonia liquor, which will, however, be clean ammonia liquor, free from tar.

The gases leaving the carbolic oil condenser are then passed through the ammonia absorber or saturator, where the ammonia is combined with sulphuric acid to form ammonium sulphate,-or is absorbed in water to produce ammonia liquor. The gases may be passed to the acid saturator without reheatmg, or they may be reheated to a higher temperature before they pass to the saturator. After the gases escape from the'saturator or absorber, they then pass to a scrubber or absorber where the llght oils are recovered therefrom, for example, b scrubbing them in an absorbent oil, such as straw oil.

The present process presents the advantags that the oils recovered are clean oils,

i. e., substantially free from heavy tar or pitch constituents, while the gases,' being likewise free from such constituents, can, advantageously be treated in the ammonia saturator and in the benzol absorber for the recovery 01' benzol and ammonia free from tar contamina tion. The advantages of freedom from heavy tar or pitch constituents are thus obtained throughout the subsequent treatment of the gas, while the heavy tar or pitch constituents are directly recovered in the form of a pitch 7 ofregulated melting point suitable for use directly as a commercial product or to be employed by blending or compounding it with tar or other pitch constituents for commercial purposes. The'pitch will be materially different from ordinar pitch produced as a residue from the disti lation of tar in ordinary externally heated tar stills. As compared with pitch of the same melting points, it will have a radically lower carbon content, andbe nary distillation. v In particular, the decomposition of oil constituents which takes place in ordinary tar 'stills is eliminated, or substantially so, in

obtained in considerably decreased yield, while the oil recovered will be considerably increased in amountas compared with the amount of oil recovered from tar by ordithe process of the present invention, so that there is present in the directly recovered creosote and carbolic oils, constituents which are not present in ordinary creosote and carbolic oils, but which are decomposed or .destro ed orconverted into other products dur ng the ordinary .tar distillation process.

Therefore the creosote and carbolic oils can, however, be employed to advantage in place of ordinary carbolic and creosote oils.

The creosote oils can be used, for example,-

directly for creosoting purposes, or they can be blended or admixed with tar or other creosote oil components to form composite products, such as solutions of coal tar in the improved creosote oils or blends of directly recovered tarry oils with the new creosote oils to give composite creosoting compositions of the character described in my companion application, Serial No. 199,629.

The carbolic or tar acid oils produced by the present process can be marketed as carbolic oils or they can advantageously be ex tracted for the recovery of tar acids of.

phenols therefrom, for example, in accordance with the process described in my companion application, Serial No. 202,736.

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

In the accompanying drawings,

'ferent gases'to Fig. 1 is a plan showing the arrangement of the apparatus; M

Fig. 2- is-an elevation; and

Fig. 3 is an elevation with parts in sectionshowing one form of electrical precipitator for cleaning-the hot gases.

In the apparatus illustrated, a coke oven .block is shown conventionally at 1, having the usual uptake pipes 2, leading to a collector main 3, common to a number of ovens. The gases from the collector .main pass through the main or pipe 4-, to an electrical precipitator 5, in which the gases are treated at a high temperature to separate itch therefrom. The gases then ass throug the 12, shown as a sulphuric acid saturator, the

light oil scrubber 13, and then out through the pipe 14, to a place of storage indicated at 5 'I Spray pipes 15 are rovided for spraying a regulated amount 0 ammonia liquor into the gases entering and in the collector main, but the amount of liquor so sprayed is limited, so that the gases escape from the collector main at the desired high temperature, for

example, at'temperatures up to around 250 0., for-example, where a pitch of melting point around 300 F. isto'be separated'from the gases, although. the temperature of clean-' ing of the gases will vary somewhat with difgive a pitch'of any particular melting point. i I

The cooling of the gases in the collector main, particularly with local over-cooling of some of the, gas in contact with the ammoma liquor, may result in throwin down a heavy tar in the collector main, which can be'drawn oil, together with anyunvaporizedv ammonia liquor throughthe center box 16 and pipe 17 to'receptacle 18. Considerable ammonia liquor can be circulated through the bottom of the. collector main,- to carry away with it any de osited tarwithout coolingithe gases to too ow a temperature, if the ammonia liquor sprays are omitted or limited, since a part only of the gas will be cooled by the ammonia liquor, while a large part of the gas will escape cooling, so that .the resulting mixture of gases leaving the collector main will be at the desired high tem erature.

e pitch particles carried in suspension in the gases entering the electrical precipitator 5 will be thrown down therein and c01 lected in the bottom thereof, and can be drawn oil through the line 19,-to the pitch receptacle 20. The gases leaving the elec trical precipitator and entering the crossover main 6- will still be at a high temperature, carrying alarge amount of oils in vapor form. These gases'will be cooled in ssing through the cross-over main 6, and will be further cooled in the first condenser 7, which will be regulated in temperature so that the creosote oil will be directly condensed therein and run out through the line and the exit of the hot cleaned gases. A baflle' 32 partiallv separates the lower chamber 33 21, to the creosote oil receptacle 22. Oil condensed in thecross-over main may likewise be drawn oil through the line 27 to this same race tacle. The gases will be cooled in the con enser 7, to a regulated temperature e. g., around 85 to 90 (1, or in general, to a temperature between 80 and 100 0., so as to leave in vapor form the oils desired in the carbolic oil products. The gases then pass into the condenser 9, where they are cooled to a low temperature, around 25 to 35 (1,, and the carbolic oil separated therefrom. This cooling can advantageously be effected by sprays 28 of water'or tar-free ammonia liquor, and the resulting oil and ammonia liquor can be drawn off to the decanter or receptacle 24, and the ammonia liquor and oil separated from each other and separately collected in the receptacles 25 and 26. The ammonia liquor can be used over again for cooling the gases or fresh oil or cooler ammonia liquor can be employed. .The ammonia liquor will be clean liquor in the sense that it will be free from tar and can therefore be more advantageously handled for the recovery of ammonia therefrom.

'The gases leaving the condenser 9 at a temperature around 25 to 35 C., will pass through the exhauster 7 and then, for example. to the saturator 12, where the ammonia will be combined with sulphuric acid to form ammonium sulphate and the gases will then pass through the light oil scrubbing system 13. where the gases will be scrubbed with a suitable oil, such as creosote oil or straw oil to absorb the benzol, etc. from the gases, after which the benzol can be recovered from the absorbent by distillation.

The electrical precipitator illustrated in Fig. 3 comprises a shell of, for example, cylindrical form, having a gas inlet 30 near the lower end thereof and a gas outlet 31 near the upper end. these inlets and outlets being for the introduction of the hot coke oven gases from the electrode chamber 34. A plurality of tubes 35 is supported in headers 36. and form the positive electrode of the separator, the shell of which is grounded. Bus bar 37 supports the electrodes 38 in spaced relation to the walls of the tubes 35. The bus bar 37 extends through openings 39 intochambers 40, in which insulators 41 support the bus bar, which is connected to any suitable source of high tension current. Coils 42 may be disposed in the chambers 40, around the insulators 41, for heating this chamber when desired, and heating medium may also be passed through the jacket surrounding the tubes by means of inlet and outlet 43 and 44, or the tubes of the electrical recipitator, and the precipitator itself, may e surrounded with insulating material (not shown) so as to prevent or reduce loss of heat by radiation while the gases are passing through the precipitator. i

In the operation of this electrical precipitator, the gas enters through the inlet 30, passing around the bafile 32, and thence upwardly through the tubes 35, where the high tension discharge between the electrodes 38 and tubes 35 effect removal of substantially all solid and suspended pitch particles from the gases in the form'of a directly recovered high melting point pitch, which flows down over the bafile 32 into the chamber 33, and thence to the outlet pipe 19.

The pitch directly recovered by the process "can be employed directly as a merchantable product and used for briquetting or fuel or other purposes, or it can be blended with other pitch or tar constituents to form a composite product, for example, a composite product such as described in my companion application, Serial No. 199,451, in which the hot high melting point pitch is blended with raw tar, etc., to form a new pitch composition. Where a pitch of desired high melting point is to be produced, the operation can be regulated as described in my said companion application, Serial No. 199,451, and the pitch can then be employed as described in said application. The process of thepresent invention is not, however, limited to the use of pitch for the production of such new pitch compensations, but the pitch can be directly employed. for example, for briquetting purposes, or for fuel purposes, or for other purposes for a high melting point pitch of low carbon content if desired.

It will thus be seen that the present invention eliminates the production of pitch at the coke oven plant and its shipment to a tar distillation plant, and its distillation at such plant for the production therefrom of distillate oils and pitch residues; the present invention providing an improved and simplified process. whereby not only a high melting point pitch but a pitch of low carbon content can be directly produced without distillation, and whereby an increased yield of an improved creosote oil can be directly recovered without requiring distillation, and whereby a carbolic or tar acid oil can also be directly recovered without having recourse to distillation, and whereby the ammonia recovery isi also improved by providing a gas free from tar. The present invention has the further advantage, among others, that it can be carried out in existing equipment of a byproduct coke oven system, with only such changes as are required, for example, for the installation of an electrical precipitator with its connecting piping and means for regulating the temperature of the gases before they reach the electrical precipitator and whilepassing therethrough, and with provision for separately condensing and collecting the creosote and carbolic oils.

; References to pitch melting points are to be understood to refer to melting points determined according to the method described in Methods of analysis used in the coal tar industry by J. M. Weiss, The Journal of Industrial and Engineering Chemistry, Vol. 10, No. 10, October, 1918, page 817. The boiling points of creosote oils are to be determined by Method D'24630 of the American Society for Testing Materials.

I claim:

a e 1. The method of treating coal distillation gases whereby creosote oil and carbolic oil are produced directly from the gases, which comprises subjecting coal distillation gases to cleaning at a suflicientlv high temperature to separate therefrom a pitch of relatively high melting point and to effect substantially com-- plete elimination of suspended pitch particles therefrom while-leaving a large amount of heavy oils in the form of vapors, the cleaning operation being effectedwithout substantial cooling of the gases, subsequently cooling the cleaned gases to a temperature around 80100'C. to separate therefrom a creosote oil and subsequently cooling the gases: to a lower temperature around 2535 C.- to sepaate therefrom a carbolic oil before passing the gases thru an ammonia absorber.

, 2. The method of treating hot coke oven gases whereby creosote oil and carbolic oil are produced directly from the gases. which comprises cooling hot coke oven ases to a regu-v lated temperature such that it retains a large regulated temperature and subjecting such gases to a cleaning operation to effect substantially complete separation of pitch constituents therefrom-in the form of a pitch havin a melting pointin excess of 145 F., and en sequently subjecting the cleaned gases to successlve condensing treatments at suecessively lower temperatures to separate therefrom first a creosote oil and then a carbolic oil before passing the gases-thru an ammonia absorben.

4. The method of treating hot coke oven gases whereby creosote oil and carbolic oil are produced directly from the gases, which comprises cooling hot coke oven gases to a regu ated temperature and subjecting such gases to a cleaning operation to e'fiect substantially complete separation of pitch constituents therefrom in the form of a pitch havin a melting point in excess of 200 F.,

and su sequently subjecting the cleaned gases to successive condensing treatments at successlvelylower temperatures to separate therefrom first a creosote oil and then a car bolic oil before passing the gases thru an ammonia absorber.

5. The method of treating hot coke oven gases whereby creosote oil and carbolic oil are produced directly. from the gases, which comprises cooling hot coke oven gases to a regulated temperature and subjecting such gases to a cleaningoperation to effect substantially complete separation of pitch constituents therefrom in the form of a pitch having amelting point in excess of 300 F., and subsequently subjecting the cleaned gases to successive condensing treatments at successively lower temperatures to separatetherefrom first a creosote oil and then a carbolic oil before passing the gases thru an ammonia absorber.

6; The method of treating hot coke oven gases whereby creosote oil and carbolic oil are produced directly from the gases, which com rises cooling hot coke oven gases to a regu ated temperature and subjecting the cooled gases to a cleaning operation to efi'ect substantially complete separation of pitch constituents therefrom in the form of a pitch havin a, melting point in excess of 400 F., and su sequently subjecting the cleaned gases to successive condensing treatments at successively lower temperatures to separate therefrom first a creosote oil and then a carbolic oil before passing the gases thru an ammonia 'absorber. 1

7. The method of treating hot coke oven gases whereby creosote oil and carbolic oil are produced directly from the gases, which comprises subjecting hot coke oven gases to a limited and regulated cooling with ammonia liquor to separate a limited amount of heavy tar therefrom while leaving the gases at a sufficiently high temperature so that upon cleaning the pitch separated will have a high melting point and subjecting the gases at such hi h temperature to cleaning so as to efiect su stantially complete removal of pitch particles therefrom without substantial cool- 5 carbolic oil.

In testimony'whereof I affix my signature.

STUART PARMELEE MILLERQ

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