US1826429A - Method of producing creosote oils - Google Patents

Description

S. F. MILLER nETHoD oF PRODUCING CREOSOTE oILs Filed July 16, 1927 ZP.. I

limes umili-Hnin" m P n 'MINVENTOR BY @W wrm@ Www-0611 ATTORNEY PatentedjOct. 6, 1931 UNITED STATES PATENT OFFICE `STUART' PARMELEE MILLER, or GLEN RIDGE, NEW JERSEY, AssIGNoRTo TEE BARRETT COMPANY, or NEW YORK, N. Y., A CORPORATION or NEW JERSEY METHOD or rRonUorNe cEEosoTE oILs vApplication led July 1.6, 1927. Serial No. 206,366.

i This invention relates to the production 'of creosoting compositions. t*

. Greosote oilslare commonly produced by the distillation of tar inordinary -tar stills. In order to obtain high yields of creo'soten o1ls,

the distillation of the tar must hel carried to a high temperature. vSuch distillation of tar, particularly at high temperatures, is accompanied by avery considerable decomposi? tion of oil constituents, with resulting increase in pitchresidue and in carbon content of the pitch residue, The pitch residue produced, particularlywhere the distillation 1s carried to a high temperature, is high in carbon content, a large part of which is produced by decomposition during the distillation from oil constituents contained in the'` tar, under.- going distillation. j 1

zo ofl'creosoteoils is carried out'attar distillation plants which are frequently remote from the .coke ovens where'the tar is produced, and

v Athe tar must bejshipped from the coke ovenplant to the tar distillation plant with added :i cost of` transportation andgexpense andv loss "of handling and rehandlin'gfthe The tar, which is cari'riedin the-'coke oven 'gases as they leave theo'vcns', is,.recove1 ed ammonia liquor, or ammonia liquor and tar, to separate out the tar constituents from the gases. The tar .thus separated .is thenv shipped, as above noted, tothe tar distillation plant, and there subjected to distillation l to the tar distillation plant and its distillationthere to produce the creosote oilsgare eliminated and in which the creosote oil is 'produced directly at the coke oven or other coal-distillation plant in a simple and advantageous manner and with materially increasedyield of creosote oil.

According to the present invention, the hot coal distillation gases as they com e from the coke ovens or retorts, are subjected to a regu- .This distillation of tar fol the lproduca@ therefrom by cooling the gases, `usually. with` lated cooling such that they will carry in 'suspended form particles of-pitch of relatively high melting point, and the gases are then subjected to a .cleaning treatment for the removaltherefrom of the suspended pitch particles, While leaving` in the gases in vapor for'm'wthe desired oil constituents, and particularly heavy oil constituents. The cleaned gases, containing such oil constituents, are

then subjected to cooling to'a low tem erature` to'separate a composite oil there rom, which wil-l be, a balanced oil containing yboth heavy and lighter oil constituents, but which as a Whole will be suitable for use as a creosote oil. The gases, after the separation of the oil therefrom, are then. passed through the ammonia labsorber or saturator, to remove ammonia therefrom, and they are then finally passed through'a scrubber or absorber for the light oils, such as benzol. By proceeding in thls way, there is directly separated and recovered a creosote oil, in a'single operation, which is available fruse as a valualle'creosote Qil, without furthertreatment.

The hot-coal distillation'gases from a coke oven leave ,the oven at a high temperature, varound 600*D to 700' C. or hi her. These gases are subjected to a regu ated cooling treatment to c'ool them 'to a regulated lower temperature', for example` a tem erature -around 200 C., or around l250" This cooling of the'hot coke oven gases' can4 be eectedby pasing through pipes exposed to the atmosphere or by introducing regulatedamounts of a cooling agent therein, for example, a limited and regulated amount of ammonia liquor, which, by vaporization, will lower the'temperature of the gases. If an ordinary collector main is employed for col- .lecting the gases from a number of ovens, 90 the cooling may take place in such collector 'main' and m the piv es leading from the coke ovens to it, and this cooling may be assisted bya limited and regulated ammonia liquor spray. l

After the gaseshave been cooled to a regulated lower temperature, but a tempera-ture still sulicientlyhigh' to carry the desired oils in the form of vapors and to carry-'in suspenv sion pitch particles of the desired high meltulated melting points such that it can advaning point, the gases are-subjected to a cleaning treatment for the removal of. the pitch particles therefrom, While leaving-the oil vvapors in the gases. This cleaning ofthe gases can be eected by a sufficiently intimate scrubhing or washing of the gases with pitch ofv similar temperature and composition to that 'of the particles carried in the ases; but it 1s more advantageously e''ected y means of an electrical precipitator through Which thegases are passed at the regulated temperature, since the electrical precipitator` will throw the pitch particles out of suspension, While leaving the oil vapors in the gases, and giving clean gases carrying the clean oil vaporspm suspension or admixture withfthem. This cleaning of the gases separates therefrom a pitch product, the melting point ot which ycan be regulated by regulating the temperature to which the ases are cooled and at which they' are cleane lf, for example,

a pitch of melting point around 300 F. is

desired, the temperature to which the gases are cooled should be regulated so that the pitch particles carried in'suspension therein willhave the desired melting point. lf pitch of'a higher y,or lower` melting point is desired, this can beobtained byin'creasing or decreass'n.; ing the temperatureof lthe gasesat the time they are subjected to the cleaning treatment 'for the separation of the pitch particles therefrom. The lower!v the tem n eratu're to which the gase'sare cooled,v the ower the melting point of the pitch, since, with lowering of temperature, somey of` the heaviest oil or grease or resin constituents originally caryried'in'the gasesv in the form of vapors, are

condensed A'as liquids kand included withthe lp'tch particles separated from the gases. -At jigher temperatures, less of these constituents fwlll. have been condensed, and more of them will be carried' in .vapor form through the precipitator' during the cleaningtreatment,

The pitch productproduced by the cleaning ofthe gases'will be a directly recovered itch of low carbon content, and in particular [1t will befree or relatively free from decomposition products formed by subjecting tar togdistilla'tion in 'ordinary externally heated tarstllls The pitchcanbev produced of regtageously be employed' directly for purposes wher'ea harder high melting point pitch is ,5 5 desired; It, may also b e blended with other -pitcl-ortarr products oroils for speciall purposes,"where its low' carbon content makesit The-cleaned gases from' which the pitch oilolglstituents, 'including heavy high boiling y011 constituents,`and constituents which are incapable of distillation, by ordinary distilla -tipon4 methods, without decompositlo'n'. :These gases wifbeelean gases, andthe vvapors car- Leases@ ried thereby will be clean vapors, in the sense that the gases and vapors will be free, or substantially free from heavy tar and pitch particles, which are carried in sus enslon in ordinary coke oven gases and w ich contaminate and form part of the tarry oil products common] produced from such gases.

According to the present invention, these clean gases, carrying vapors of a wide range of-oils therein, are subjected to condensation to separate creosote oil therefrom, or an oil composition valuable for use-as a creosote oil. Where the gases are 4cleaned at a high temerature, they will still contain in vapor orm, heavy or high boiling oil constituents, and they may also contain 'in considerable amount constituents which, by themselves, would be of a` greasy or resinous character at ordinary temperature, but which when condensed with the lighter oil constituents,

blend therewith to form' a homogeneous creosote oil composition. Y

The cooling of the gasesto separate the rcreosote oil therefrom may advantageously be effected-in a single condenser or in a series of condensers such as are commonly .employed at coke oven plants for .the condensatemperature around 25 to 35 C., at 'which temperature most of the oil vapors-will be separated exceptk those subsequently recovf ered in the light oil scrubbers or absorbers.

By carrying the condensation to a low temperature, there willbe included inthe product light oil constituents, which, by themselves, would have a relatively low boiling point.l Nevertheless, -where heavy oils are also included in the product, the lightol constituents blend therewith, so that the composition as a whole will give only a small per? centageof o l when subjected to distillation to a temperature up tol-around 210 C., 'for example,not more than five per cent at' 210 C., although in some casesa somewhat in-l creased amount mag` distill at such tempera! ture. Similarly.' when subjected to distillation u to 235 C., the oil will not give more than a out 25 per centof distillate, although in some Acases the amount may be somewhat higher, for example, uptoaround 35 or 40 per centv .Where, however, the heavy high boiling oil constituents, including grease. andA resin constituents, are retainedin-the gases andcondensedas 'part of vthecreosote o il there f will result a blended productfcfaffcomposite heavyoils .balancing the'lighter oils and giv` l ing 'a well balanced creosp 'il compositiom characterand ofa balancedcha'acter, the

iso

The relative proportion of' heavy constituents and of light constitutent'scan be varied and-regulated by regulatingfthe temperature of the cleaning operation at which the' pitch a is removed from thegasesandthe tempera. 'ture of the condensing operation. ,Diii'ere'ntf coal distillation gases-may differ materially from each other in their vapor content and to some extent in the character lof the vapors m andthe proportions-.of the vapor constituents which they contain','depending, forexample,

on the character of the coal subje Ited to the coking or distillation, 'the mannerv in whichthe coking or distillation .--is' carried out, Whether-'with "rapid or slower coking, the temperature of the vcoking operation,l the type of jcoking retort, etc. However, by. cooling the gases to a regulated'temperature and separating the pitch particles. there-v from, it can readily be ascertained. whether the pitch separated is of the desired melting point, and if a higher or lower melting vpoint isdesired, the temperature of the cleaning can be increasedor decreased. If, Afor e2;-v

ample, apitch of a melting point laround 300 F.' is desired, thevcooling can be regulated so that a'pitch of this.v melting point will be separated when the gases are "cleaned .in theelectrical precipitator.- A ,tempera- $0 ture around 250o C. may be. sufficient with `some coke oven gases to 'giveal pitchlof suchl melting point, although .the temperature may vary somewhat Y'with .different cokeoven gases. Thev properv temperature, can readily 86 be ascertained, as above noted,.by noting the of oils will be recovered, 'including heavy loil or grease or resin constituents, which Will blend with.the lighter oil constituents in the v new composite creosote oil product. Where a softer pitch is desired, for example. a pitch having a meltingv point around 200 F., a

correspondingly lower temperature can vbe'.`

y employed for the cleaning treatment, and the cleaned gases will carry less of the heavy oil constituents, and the final temperature of condensation muybe somewhatv higher, :so

that lessof the lighter oils will be lncluded inthe rodu'ct, if a somewhat heavier creof 50 sote o' is desired.

The cooling ofthe cleaned gases for the separation of the creosote oil therefrom may, as above noted, be carried out in either di rect ori'n'direct coolers or condensers and in. a single fraction or series of fractions, partl or 4a temperature around 25 yto 35 C., there operation and a materially' increased portionv perature,L around 25 to 35 C., before they all ,of'which may be combined to give the creosote'oil. Where a single total condenser is employed for condensing the gases, e. g., from a temperature around 200 or 250 C. to 1 will be'fdirectly obtained a composite oil product. containing a wide range of oil constituents, including both heavy high boiling constituents and lighter low boiling constit' uents, which; however, in the blended and balanced product will so blend that the product as awhole will not begin to distill until it reaches, e. g., a temperature around 200 C., andwill give only small percentages at higher temperatures, e. g., around 210.'1'C. The inclusion of the heavy'constitutents in such a product makes possible'the utilization of the total oil content recovered from the gases, including the lighter oil constituents, to give a balanced creosote o il.

v Thecooling of l'the 4gases canI advantageou'sl'y be carried out vwithfdirect'introduction of water, or ammonia liquor free from tar, into the gases. inasmuch as the gases themselves-are free from. heavy tar and pitch constituents, the water employed for cool ing' themv will give an ammonia -liquor free from tar,- and which, when it has increased in ammonia content to the .desired extent,l can be subjected to distillation or treatment for the recovery off'ammonia ,therefrom without the objections incident vto thedistillation" of tar-contaminated liquor. When water or ammonia liquor is employed, the gases ,will be rapidly cooled-to aglow temperature, so that thev entire cooling .operation can becarriedout in one ortwostages,.down to a temperature around-25fto 35C.' Y

After the condensation of 'the clean oils therefrom, ,the which' Awill Abe clean gases,free from suspended- 'tar' particles, are then passedt'o the ammonia absorber' or saturator, and the'ammoniastill carried in the gases willube recovered therefrom, e.v g., as ammonia 'liqlorf' :or ammonium sulphate, which will he free from ta'r contamination. The completion of` the separationyof'sus* pended oil particles from the gases 'can be effectedl b a further cleaning of the gases with an e ectrical precipitator at `a low tem*- enter the ammonia absorber- .or`saturator. After` the gases leave thesaturator or absorber, they then pass' through the' scrubber orjabsorber for light oils,- leaving clean gases 19 for use. for fuel or otherpurposes. l

he'cresote oil directly recovered from the coke O Yen gases, according to the resent in.

vention, differs materially 'from t e creosote oils produced .as distillate oils Aby'dis'tilling 125 coal tarzin ordinary tarstills. vIt contains. oil components -which,.in .the distillation vof tar in ordinary tar stills, are converted m'to carbon or pitch. con

stituents 'are ld H- H lectin ordinary tar distillation methods for making 'creosote oils, are retained in the cresote oil prepared according to the process of the present invention. This creosote oil accordl`1ngly represents a greatly increased yield of `cresote oil, directly recovered from the coke oil, by=regulating the temperature of clean- L. ing at which the pitch is separated and the y temperature of cooling for completing the condensation of the oils from the gases. Even where yt-he pitch separated from the f gases has a melting point around 160 or 170 F., the total oil subsequently condensed from the clean gases may be employed as a creosote oil. Where a higher melting point pitch is recovered at a higher temperature of cleaning of thegases, for example, a pitch of meltingI points around 200 F., the total oil recovered from the gases can also be employed as acreosote oil and will be a somewhat heavier oil than that abovel mentioned. With a still higher melting ,point pitch separated at a higher temperature, for example, a pitch ofmelting point around 300 F., the total o1l recovered will be a rather heavy creosote oil, While with the separation of a still higher melting pointpitch around 400 F., melting point, at a higher temperature cleaning of` the gases, a materially increased yield of creosote oil will be obtained and the entire oil will be a heavy creosote' oil, which will be valuable for useswhere aheavy oil is desired. Because of the inclusion in the creosote oil ofthe heavyconstituents, including heavy oils of boiling point above 350 C., and

` including also constituents which by themvselves would be of a `greasy or resinous character, the composition has the advantage that when employed for creosoting purposes, or

` as part 0f a creosoting composition, it supvobtained. According to the radically lincreased yields of plies not only lower boiling constituents which may slowly vaporize, but relatively large amounts offhigher boiling constituents which remain. as a valuable residue in the material creosoted.

In ordinary externally heated stills of e. g. 10,000 gallons capacity in which successive changes ofttar are distilled to make pitch and distillate oils, they Aoil yield obtained `in distilling tar to produce avpitch of 170 Fm. p. yisfonly. about 33% of the tar distilled; in distilling vtar to produce-pitch of'200 F. melting point, the oil yield is around 38% in distllling to 300 F.,m. p. pitch the oil yield is around 44%; and `coking maybegin to take place before a pitch of v400 F. m. p. can be present process,

a different and LezamaY lsuperior roil product can be recovered. For example, when pitch of around 170 F. m. p. is directly separated from coke oven gases, according to the present process, an oil' yield of around 48% or vhigheris obtained; when 200 F. m. p. pitch is produced, the oil yield is around 55% or higher; when 300 F m. p.

pitch is produced, the oil yield is around 7 0% or-higher; when 400 F. m. p. pitch is roduced the oil yield is around or hig er; andit is possible to produce pitch of even higher melting point and obtain even higher yields of creosote oils. These radically increased oil yields are accompanied by a radi- -cal reduction in the amount of pitch of correposition and formation therein of such decomposition products.

As compared with ordinary methods of producing creosote oil, it willaccordingly be seen that the present process avoids the necessity of separating and collecting "tar from the coke oven gases and the handling and shipment of this tar, and its subsequent distillation, thus greatly simplifying land reducing the expense'of producing vvthe creosote yield'of creosote oil of new and improved composition, containing constituents not contained in ordinary distillate'oils While simultaneouslythere is producedfa relatively high melting point pitch which is nevertheless of relatively low carbon content and whichrepresents a materially lower proportion or percentage of the total tar content of the coke oven gases than is represented by the pitch residue from ordinary tar stills distilling a corresponding amount of the tar. Y

The/invention will be further described in connection with the accompanying drawings, which illustrate, in a somewhat conventional and diagrammatic manner, an apparatus suitable for the practice ofthe process of the invention; but it isintended and will be understood that the invention is illustrated by, but isnot limited to the Ispecific apparatus and procedure described.

In the accompanying drawings Fig. V1 shows in a conventional and diagrammatic manner, part of 'a by-product recovery system of a coke oven plant, modified for the tion, an l l Fig.- 2 is an yelevation partly insection of one` `form of electrical"precipitator' illustrate'd in `AFig.-1,"`th=.} specific 'con/'struction of oil, while also giving a radically increased `the precipitator being that of the McCloskey patent, No. 1,752,920 issued April 1, 1930.

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 numberof ovens. The gases from the collector main pass through the main or pipe 4 to an electrical precipita tor 5, in which the gases are treated at the required high temperature to separate pitch particles therefrom and to leave clean gases carrying the clean oils in the form of vapors. The hot clean gasesV from the electrical precipitator pass through the cross-over main 34 to the condensers indicated conventionally at 35, in which the hot gases are cooled to separate the clean oils therefrom by introduction of cooling liquid such as water through the pipes 40. The condensers shown are the type in which the gases enter first at the bottom of one compartment or condenser and are cooled therein by direct contact with a coolf ing liquid such as Water or ammonia liquor, and then passed to the bottom of the next compartment or condenser, Where they are further cooled by direct contact with cooling liquid, after which the gasespass to the exhauster and thence to the ammonia saturator and light oil scrubber. In the drawings the exhauster is indicated at'36,.the ammonia saturator at 37 and the light oil scrubber at 38, the gases then flowing through the line 39 to a as storage or to a place of use.

he condenser is shown as having the outlet at the bottoms .of both` compartments leading to the same receptacle or decanter 26, this arrangement being such that the total condensate in the condenser will be collected together as a creosote oil. The condensate that forms in the'cross-over main 34 may be y' lcollected. in the receptacle or decanter 27,

While that condensing in the outlet pipe from the condensers may be collected in the further receptacle or decanter 28. The oils from all of these decanters or receptacles may be blended'` to make a composite product containing all of the oils condensed from the.

gases; or the oils from the separate compartmentsof the condensers may be collected separately `and mixed in desired proportion.

The clean oils condensed from the gases may be extracted for the recovery of tar acids therefrom, althou h it is not necessary to extract them, and ti able creosote oils ofimproved properties for osote compositions by blending with other ingredients, such astar, Where a solution of tar in oil is desired.

. Where tar acids are to be recovered from the creosote-oil, the entire oil can be extracted, to give substantially the total taracid'content of the oil, including-higher phenols or tar acids v as well as lower phenolsfqntar acids, in which v e oils can be utilized directly without further treatment as merchantcase the extracted creosote oil Will be free or substantially so from tar acids, but will otherwise be practically unchanged in composition. Instead of extracting the total oil,

only the lighter fraction or fractions rich in lower tar acids may be extracted, and the resulting neutral oil blended back with the heavier unextracted oil, in which case the resulting creosote oil. will be relatively free from lower boiling tar acids. The extraction of tar acids, Where this is to be eected, may be, for example, with a ten per cent solution of caustic soda brought into intimate interinixture with the oil, and by setting free the tar acids from the resulting carbolate solution, e. g. by treatment with carbon dioxide.

The electrical lprecipitator illustrated in Fig. 5 comprises a shell 5, for example, of cylindrical form, having a gas inlet 6 near the lower end thereof, and a gas outlet 7 near the upper end, this inlet and outlet being for the introduction of the hot coke oven gases and the exit of the hot cleaned gases. A baille 8 partially separates the lower chamber 9 from the electrode chamber 10. A plurality of tubes 1l is supported in headers 12 and forms the positive electrode of the separator, the shell of which is grounded. Bus-bar 14 supports the electrodes 15 in spaced relation to .the sides of the tubes 11. The bus bar 14 extends through openings 16 into chambers 17, in which insulators 18 support the bus bar which is connected to any suitable source of high tension current. Coils 19 may be disposed in the chambers 17 around the insulatois 18 for heating these chambers when desired and the heating medium may also be passed through the jacket surrounding the tubes by means of connections 22 and 23; or the space between the tubes may be filled with insulating material to reduce loss lof heat by radiation or cooling while the gases are passing through the precipitator.

In the operation of this electrical precipitator, the gas enters through the inlet 6, passing around the battle 8 and then upwardly through the tubes 11, where the high tension discharge between the electrodes 15 and the tubes 11 effects removal of substantially all solid and suspended particles from the gases in the form of a directly recovered high melting point pitch which flows down over the battle 8 into the chamber 9, and thence to the outlet pipe 20. Manholes 2l permitaccess to the interlor of the precipitator.

In the operation of the apparatus illustrated, the coke oven gases from the individual ovens enter the collector main and then pass through an electrical precipitator at a high-temperature, and are there cleaned and entrained pitch and other particles removed therefrom, leaving clean hot gases containing the oils in vapor forni. The gases may be cooled in the collector main b a regulated and limited spray of ammonia iquor, or am-V f in the main will ing pitch.

`which will be drawn monia liquor may be flushed through the bottom of the main, Where it will comein surface contact with the hot gases and cool them to some extent while keeping the main clear from obstructions due to accumulated tar orY pitch. Excessive cooling of the gases should be avoided, although some local over-cooling may take place. The average temperature of the gases, however, when they leave the collector main and pass through the electrical precipitator should be vsuiiiciently high to give a. pitch of the desired high melting point and to leave oils of the desired character in vapor form. Owing to local over-cooling, the product separated in the collector main may be a heavy tar admixed with ammonia liquor, orti into the receptacle or decanter 30. v i

The regulation of the tem erature in the collector main may also be eiiiected by circulation of hot pitch through the collector main so as to avoidexcessive cooling, and to keep the main free from. accumulation of hard pitch. By circulating a sufiicient amount of hot pitch through the collector main, the main can be kept free from such obstructions, and any tar orpitch constituents separated be blended With the circulat- Some distillation othis pitch may take place with resulting increase in vapor/content of the gases, and tar may be added to the pitch and may likewise undergo distillation. Such-distillation will result in enrichment 'of the gases in the vapors distilled from the tar or pitch, and such enrichment will materially7 change the temperature of operation of the electrical precipitator to separate a pitch product of a particular melting point. With such enrichment, the temperature of the gases passing through the lprecipitator must be materially higher to give a pitch of the same melting point, than Where normal coke oven gases are employed Without such enrichment ,and .with any large amount of distillation of tar and enrichment' of the gases,

a very much higher temperature `for cleaning of the gases should be employed to retain theincreased amount of vapors in the vapor state, sired high melting point. Where ammonia liquor in limited amount is employed in the collector main, the gases will not be enriched, but will carry only their normal tar and vapor content. Pipes forleading cooling liquid to the collector main and goose-neck are indicated at 41, and the outlet for the tar or pitch etc. at 24 leading to receptacle 25.

In order better to regulate the temperature of the gases, the collector main and individual uptake pipe from the individual oven to the collector main and also the connecting main or pipe 4 in the electrical preciitator may be insulated to reduce and regulhte the loss vof heat due to atmospheric cooling.

and to give a pitch 4ofthe de-` With gases entering the electrical precipitator at a regulated temperature, for eX- ample, around 200 C. or 250 C., or such a regulated temperature that a pitch of the desired melting point will be obtained, e. g. a pitch of melting point of 300 F. or 400 F.,.there will be recovered from the precipitator a pitch of the desired `melting point, while the gases will leave the precipltator still at a high temperature and carry a large amount of oil in vapor form, including heavy or high boiling oil constituents, a considerable amount of which will boil above 350 C., and some ofv which may, as above noted, be of a grease-like or resin-like character in an isolated state.

The lclean gases leavin theprecipitator at 'a high temperature, wi l then pass to the condensers 35, and be there cooled, and the oils condensed therefrom in the form of clean oils with increased yield `as compared with the yield of distillate voils obtained by distilling coal tar in ordinary stills. By condensing all of the oil constituents together, including both light and heavy oil a balanced product is obtained, so that the product as a whole can be employed as a creosote oil, thus giving the maximum yield of creosote oil as a directly recovered oil of distinctive and improved composition as compared with ordinarycoal tar distillate oils.

References to pitch meltingl points refer to melting points determined'by the 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.

temperature such that pitch particles of relativelyhigh melting oint are carried in 'suspension therein, whi e creosote oils are contained in vapor form, then cleaning the gases without cooling them to separate pitch particles therefrom and to leave clean gases containing creos'ote oil vapors and cooling the cleaned gases to separate therefrom an oil suitable for use as creosote oil, before passing. the gases through an ammonia absorber.

2. The method of treating coal distillation gases, which comprises subjecting them to the action of an electrical precipitator at a temperature such that'pitch` particles of relatively high melting point are separated from the gases, -while oil constituents, including v uents, before passing the gases through an ammonia absorber.

3. The method oftreating coke oven gases whereby creosote oils are produced directly therefrom, which comprises subjecting the coke oven gases to a cleaning treatment at a sufficiently high temperature to separate therefrom a pitch product having a melting point in excess of about F. and cooling the resulting cleaned gases to separate therefrom an oil suitable for use as a creosote oil, before passing the gases through an ammonia absorber.

4. The method of treating vcoke oven gases whereby creosote oils are produced directly therefrom, which comprises subjecting the coke oven gases to a cleaning treatment at a sufficiently high temperature to separate therefromv a pitch product having a melting point in excess of about 200 F. and cooling the resulting cleaned gases to separate therefrom an oil suitable for use as a creosote oil, before passing the gases through an ammonia absorber.

` 5. The method of treating coke oven gases whereby creosote oils are produced directly therefrom, which comprises subjecting the coke oven gases to a cleaningtreatment at a suflicentitly high tem erature to separate therefrom a pitch pro uct having a melting point in excess of aboutl 300 F. and cooling the resulting cleaned gases to separate therefrom an oil suitable for use as a creosote oil, before passing the gases through an ammonia absorber.

6. The method of treating coke oven gases whereby creosote oils are produced directly therefrom, which comprises subjecting the coke oven gases to a cleaning treatment at a sufficiently high temperature to separate therefrom a pitch product having a melting point in excess of about 400 F. and cooling lthe resulting cleaned gases to vseparate therefrom an oil suitable for use as a creosote oil, before passing the gases through an ammonia absorber.

7. The method of treating coke oven gases whereby creosote oils are produced directly therefrom, which comprises subjecting the coke oven gases to cleaning with an electrical precipitator at a sufficiently high temperature to separate therefrom a pitch of relatively high meltin point and to leave oils, including oils of igh boiling point above 350 C., in the form of vapors and cooling the vresulting cleaned gases to separate therefrom an oil suitable for use as aI creosote oil, before passingthe gases thru an ammonia absorber, such cooling including cooling of the gases to a temperature around 25 to 35 C.

In testimon whereof I affix mysignature.

STUA T PARMELEE MILLER.

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