US1981626A - Refining oils - Google Patents

Description

Nw.2o,1934.` GEMCCLOSKEY 1,981,626

REFINING OILS BY 7J, ATTORNEY Nov. 20,1934. G, E. MocLosKEY REFINING OILS Filed Sept. 24, 1931 2 Sheets-Sheet 2 vATTORNE Patented Nov. 20, l1934 PATENT OFFICE REFINING OILS Gregory E. McCloskey, South Orange, N. J., as-

slgnor to The Barrett Company, New York, N. Y., a corporation of New Jersey Application September 24, 1931, Serial No. 564,753

16 Claims. (Cl. 202--30) This invention relates to the rening of creosote oils, and in its more specific aspects is drected to the removal of water and low boiling light oil constituents from such oils.

5 Creosote oils are generally marketed according to specifications which limit the maximum permissible content of water and/or low boiling light oils. For example, in many instances specica- `tions provide that the oil shall not contain in ,0 excess of a stated amount of water, say 2% or 3%,

and that the oil shall be so constituted that nothing distills over up to a temperature of say 200 C. It is also quite customary to specify that not more than 5% of the oil shall distill over up to 210 C.,

5 not more than 25% at 235 C. and so on, and additionally, that the ash point of the oil shall/not be below a certain minimum temperature. Further, it is usual to specify the maximum permissible coke residue of an oil (American Society for Testing Materials, Test No. D-168 -27),' themaximum permissible residue left on distillation to 355 C., and that the oil must meet a given Float Test on the residue left on distillation at 355 C., (American Society for Testing Materials, Test No. D-139-27). -These latter tests are a measure of the content and character of heavy constituents not volatilized in the distillation test which may be objectionable in oils used for many purposes. In the sale of creosote oil, any one or :0 all of the above items may be involved.

As is known in the art, the distillation of tar yields an oil fraction known as creosote oil. This fraction may contain low boiling oil constituents, and it is sometimes diicult to provide a product meeting the required specifications because of the `presence of water and/or low boiling constituents in the creosote oil fraction; 'I'his is particularly true where the oil is produced by distillation of tar by direct contact with hot coke-oven gases =0 because in such operation thevolatile.. products of the tar distillation contain not only benzol a'nd light oil constituents present in the tar, but also a substantial quantity of such constituents present in the raw coke-oven gas used for distillation .5 0f the tar. Creosote oil condensed from the volatile products of this type of tar distillation tend to include substantial quantities of light oil con` stituents and it is to .this type of ycreosote oil that the present invention is particularly applicable. .o The principal object of the present invention is to provide a. process for treating creosote oil adapted to reduce the light oil and/or water content of the creosote oil. It is a further object of the present invention to provide a process for treating creosote oil' which will not result in objectionable oxidation and polymerization of constituents in the oil and which will produce an oil low in light oil constituents and water. Another object of the invention is to provide a process for removing water and/or low boiling light oil constituents from creosote oil in such manner that the low boiling oils thus stripped and removed from the creosote oil may be readily recovered.

In accordance with the present invention crea.- sote oil containing objectionable quantities of light oil constituents or water is treated with a gas, preferably an inert gas such as coke-oven gas, to effect the removal of such objectionable constituents from the oil as vapor in the gas. Preferably the temperature of the gas is maintained such that the temperature of the oil being treated will not exceed substantially 95 C., and it has been found that by operating in this manner the objectionable constituents may be removed from the oil without appreciable polymerization of constituents of the oil and consequent increase in the coke residue and residue left 0n distillation of the oil at 355 C.

A fuller understanding of the nature and 0bjects of the invention may be had by reference to the following detailed description when taken in connection with the accompanying drawing in which: n

Figure 1 is a diagrammatic plan view showing one embodiment of the apparatus for carrying out the present process, together with a diagrammatic illustration of somuch of a battery of by-product coke ovens and a by-product recoverysystem as is desirable to acquire an understanding of the present invention;

Fig. 2 is a diagrammatic vertical section taken approximately on the line 2--2 of Fig. 1, and

Fig. 3 is an enlarged diagrammatic vertical section, taken approximately on the line 3-3 of Fig. 1, of a hot gas distillation apparatus asso- 9.5 ciated with coke ovens.

Referring Vto Fig.1 of the drawings, the re!- erence numeral 10 indicates generally a battery of by-product coke ovens 11. As is well known in the art the several coke ovens 11 are each pro- 100 vided with a 'vertically disposed individual gas collecting pipe 12, the lower end of which opens into its respective coking chamber. The upper ends of the collecting pipes 12 feed into a common collector main 13 which communicates through 105 the cross-over pipes 14, with the inlet conduit 15 of a by-product recovery system.

V 'I'he by-product recovery system comprises generally the primary gas cooler 16, exhauster 16a, tar extractor 17, reheater 17a, ammonia. ab'- 110 sorber 18, secondary gas cooler 19, one or more benzol or light oil absorbers 20, and a finalv cokeoven gas holder 21, all of which individual elements of apparatus 'are connected together in series as shown on the drawings. The extractor l17 serves to separate from the gas stream the condensed tar which has not separated previous to this point. In the absorber 18, the free ammonia from the gasstream to which has also been added the free ammonia liberated in the fixed ammonia still is removed from ythe gases by direct contact with sulfuric acid. After further cooling of the gas stream in the secondary cooler 19, the light oils contained in the gases are customarily separated therefrom in the benzol absorber 20 in which the gases are scrubbed,

further description of the construction of such apparatus is unnecessary.

Tar and liquor removed from the gas stream by the extractor 17 and condensate from the primary cooler 16 are discharged into the decanter 25 in which separation of tar and ammonia liquor is effected. Tar owing out of decanter 25 is ,pumped through the line 26 into the tar storage tank 27.

Although the present invention contemplates the treatment of creosote oil produced by any method, the invention is particularly applicable to the treatment of creosote oil obtained in. the

. distillation of tar by direct Acontact with hot cokeoven gases. Accordingly, apparatus for recovering creosote oil from tar by this process is illustrated, diagrammatically, in plan in Fig. 1, and in vertical section in Fig. 3. In Fig. 3, the horizontal line 28 indicates the top of the coke-oven battery.

The lower ends of the vertically disposed standpipes 30 open into coking chambers, and the upper ends communicate with the hot gas collector main 3l. The reference numeral 32 indicates generally a tar still of the type having therein one or more rapidly rotating ro'lls 33 for creating an intense spray of tar or pitch from the distillation of tar within the hot atmosphere of the still. Rotation of the roll 33 may be elected in any manner as by direct connection to a motor 34. Hot gases collecting in the main 31 pass into the still 32 through a pipe connection 35. Still 32 is proided with an outlet 36 to permit withdrawal of pitch from the still. Gases from the still 32 are discharged into the lower4 end of a hot gas saturator 37, having therein a horizontally disposed grid 39 serving to support packing material indicated by the reference numeral 40. Hot partially distilled tar running out of the lower end of the gas saturator 37 ows through the pipe connection 42 into the still 32.

'I'he gas space inthe saturator 37 above the upper surface of the packing is connected to the lower end of a rectifying tower 44 by means of a gas conduit 45. The tower 44 comprises a vertically disposed chamber provided near its base with a grid 46 which supports a body of packing material 47. From the tower 44 the gas passes to a tar preheater 38 which may be superposed on the top of tower 44. 'I'he tar preheater includes a tar preheating and gas cooling coil 48,' the discharge end thereof being connected to a pipe 49 through which heated tar is fed over the packing 40 in the hot gas saturator 37. It will be understood that the saturator 37 is provided in the gas space above the surface of the packing 40 with any suitable means by which the tar discharged into the tower 37 through the pipe 49 is sprayed or dispersed evenly over the upper surface of the packing. The inlet end of the tar preheating coil 48 is connected to pipe 51 which in turn communicates with the tar storage tank Heavy oil formed bythe condensation of oil vapors in the tar preheater 38 ows over the packing 47 in the rectifying tower 44, and out of the bottom thereof, and thence through a pipe 52 into a vsuitable heavy oil storage tank 53. Uncondensed gases are withdrawn from the preheater 38 through a conduit 54, and are discharged into the vertically disposed condensing chamber 55, the latter being of any desirable construction and having therein a cooling coil 56 to bring about condensation of creosote oil. Cooling liquid may be circulated through coil 56. The gas may enter the top of condenser 55 and be discharged from the bottom thereof as shown in the drawings, or it may enter the bottom thereof and be discharged from the top. A direct condenser in which the cooling medium comes into direct contact with the gas being cooled may be substituted for the indirect condenser shown. Uncondensed gases are withdrawn from the condenser 55, and are conducted through the conduit 63, having a suitable blower 64 therein, and are discharged into the collector main 13.

Creosote oil and ammonia liquor formed b y condensation in the condenser 55 flow from the lower end thereof through the pipe 58 into the decanter 59, in which the ammonia liquor is separated from the oil, the liquor flowing through the outlet 60, and the oil flowing from the decanter 59` through the pipe 61 into the creosote oilv collector 62.

The creosote oil thus obtained'as the result of distillation of the tar by direct contact with hot coke-oven g'as may contain appreciable quan tities of water and light oil constituents and is treated to effect removal therefrom of such undesirable constituents in a blowing tower 65 shown in plan in Fig. 1, and in section in Fig. 2.

Referring to Fig. 2, the tower .65 comprises a vertically elongated, preferably cylindrical chamber provided near its lower end with a horizontally disposed grid 66 which, in conjunction with the bottom and lower vertical walls of the tower, forms a chamber 67. Resting on the grid 66 is a body of packing material 68, the upper surface of which is spaced from the upper end of the tower so as to aiord a chamber 69 within which is constructed a spray device 70. It will be understood that the spray 70 may be of any suitable construction which will cause an even distribution of liquid over the upper surface of the packing material 68. The creosote oil collector 62 is connected to the spray 70 by a pipe line 72 having therein a pump 71. A device (not shown) for measuring the oil is preferably inserted in the line 72. Oil collecting in the lower chamber 67 of the tower is withdrawn therefrom preferably owing by gravity into the oil storage tank 74 through the pipe line 75.

vAccording to the preferred embodiment of the invention, the creosote oil iscontacted in tower 65 with coke-oven gas from which the light oil constituents have been separated. This treatment of the oil with the coke-oven gas is brought about by withdrawing required quantities of gases from the by-product recovery system, at some point preferably beyond the benzol absorber, and blowing such gases through the tower 65. As indicated on the drawings, the gas conduit 77 at one end opens into the pipe 24 connecting the light oil absorber 20 and the gas holder 21. 'I'he opposite end of the conduit 77 discharges into the inlet side of a blower 78 which feeds the gases thus taken from the by-product recovery system to the gas conduit 79 through which they are delivered for utilization. A desired portion of the gas passing in line 79 is withdrawn through a line 79a and delivered into the chamber 67 in the lower end of tower 65. An orifice meter (not shown) is preferably placed in line 79a to measure the volume of gas being used in blowing tower 65. The gas stream passes out of the upper end of the blowing tower and into the conduit 81, whence the gases are discharged back into the vmain gas line of the by-product recovery system at a point preferably ahead of the benzol absorber, for example as indicated at 82 in the pipe connection between the secondary cooler and the absorber 20.

The tower 65 is also provided with an inlet connection 83 and a suitable vent 84 by means of which the tower may be purged with steam when desired. It will be understood that all the liquid pipes and gas mains are provided at suitable points with necessary valves to facilitate proper operation of the apparatus.

The process is carried out substantially as follows: The several coke ovens l1 in the battery are operated in the customary manner, and the gases formed in the coking chambers rise through the individual uptake pipes 12 and enter the collector main 13. The gases are thence conducted through th'e cross-over' mains 14, the inlet conduit 15, and into the primary gas cooler 16. From the cooler, the gases pass in succession through the exhauster, the tar extractor, the gas reheater, the ammonia absorber, the secondary cooler, and the benzol absorber, and finally into the gas holder 21. The treatment of the oven gases in the by-product recovery system constitutes no part of the present invention, and it will be understood that such gases are cooled, the tar, the ammonia, and the light oil constituents are separated from the gas stream in the customary manner. The tar condensed out of the gas stream and removed therefrom in the primary cooler and bythe extractor 17, after passing through the decanter 25, is pumped into the storage tank 27. The gas leaving the benzol absorber and entering the gas holder 21 through the pipe connection 24 is a representative coke-oven gas, the analysis of which may be approximately as follows:

The gas is thus substantially free of oxygen and oxidizing constituents. The temperature of the gas stream leaving the light oil absorber will in general be approximately C., although this temperature may of course vary somewhatvwith different installations and different atmospheric conditions.

The operation of the tar distillation and creosote oil recovery system is as folows. Hot raw coke-oven gases are withdrawn from the coking chambers, and pass into the insulated header 31 of the direct recovery apparatus through the several stand-pipes 30. The gases thus collected in the main 31 ow through the pipe connection 35, and enter the still 32 at temperatures ranging from say 450 to 850 C. Tar, which may be that removed from the main gas stream of the by-product recovery system and collected in the storage tank 27, or any other tar, is distilled in the still 32. To effect such distillation, tar is withdrawn from the tar storage tank 27 by means of the pipe 51, and pump 51a and fed into the tar preheating coil 48, whence the heated tu' flows through the pipe 49 and into the upper end of the hot gas saturator 37. The gas saturator is provided at its upper end with a suitable means for spraying the preheated tar over the upper surface of the packing material 40. The tar trickles downwardly over the packing, at the same time contacting with the upwardly rising stream of hot gas from the still 32, thus becoming further heated and more or less distilled. Tar collecting in the lower end of the gas saturator 37 runs into the still 32 through the pipe connection 42. As noted, the still 32 is preferably of the type having one or more rapidly rotating rollers 33 which create within the still chamber above the surface of the liquid therein, a nely divided spray of tar, thus effecting intimate contact between the liquid particles and the hot gases charged into the still from the collector main 3l. The temperature in the still 32 may be maintained around 350-400 C. The pitch formed in the still 32 which may, for example, have a melting point of say 340-360 F., is continuously withdrawn through the pipe connection 36. 'Ihe gaseous products of the distillation operation pass out of the still 32, and into the lower end of the hot gas saturator 37. The hot gases thence rise through the packing 40, and are contacted with the heated tar sprayed into the upper end of the saturator from the tar inlet pipe 49. The purpose of the gas saturator 37 is to eil'ect a preliminary distillation of the tar, thus acting to saturate the gas with volatilematerial and also to recover from the gas stream particles of pitch and partially coked material which may have been entrained in the gas stream from the still.

The gases, which may be at a temperature of about 240r260 C., leave the upper end of the saturator 37 and are discharged into the lower end of the rectifying tower 44, thence passing upwardly through the packing 47, into the tar preheater 38 and around the tar heating coil 48. In this preheater, the gases are cooled -to some extent, and condensation of heavier oils takes place. Oils so condensed iiowonto the upper surface of the packing 47, and run downwardly therethrough, thus providing reflux for the rising i gas stream. In the preheater 38, the cooling eifect of the tar heating coil 48 is suflicient to cause condensation of an appreciablequantity of heavy l oil, say about 25-30% of the volume of tar treated.

conducted through the gas conduit 54 into the condenser 55. In the latter, further condensation of the gas is eiected by circulation of a suitable cooling medium through the coil 56. The cooling in condenser 55 is carried out to such an extent that substantially all the oil which will condense at a temperature of 40 C. or higher is condensed and withdrawn as liquid through the outlet pipe 58. The remaining uncondensed gases are conducted through the gas conduit 63 into the collector main 13 by the exhauster 64. The condensate from the condenser 55 may constitute around 45% of the volume of tar treated and is a creosote oil containing various quantities of dissolved and admixed water, and some light oil constituents.

According to the present invention these objectionable components of the creosote oil, such as Water and/or low boiling oils whether they come originally from the tar being distilled or from some other source, such as the coke-oven gas used for distillation, may be removed from the oil without harmful effect thereto, by blowing the oil with a gas which will carry oif such objectionable constituents. 'I'he gas used to effect removal of water and low boiling*l constituents from the creosote oil is preferably an inert gas such as coke-oven gas after removal of benzol or light oil. The blowing of the creosote oil with the coke-oven gas may be carried out, according to one embodiment of the invention, by contacting the oil and the gas in counter-current flow relation in a suitable tower.

Creosote oil is withdrawn from the collector 62, and pumped through pipe '12, into the spray 7 0 in the blowing tower 65, and is thus charged evenly dispersed over the upper surface of the packing 68. Simultaneously with the initiation of the feed of the creosote oil into the upper end of the blowing tower, coke-oven gas, at a temperature of around say 30 C., is withdrawn from the gas line 24 by the blower '18 and a portion thereof is pumped through the gas conduit. 79a into the chamber 67 in the lower end of the blowing tower 65. During the passage of the gas through the blower, the temperature of the gas may be raised somewhat depending more or less'upon the increase in pressure.- Thetemperature of the gas entering the tower is preferably maintained low so that polymerization and objectionable action on the oil is avoided and preferably should be low enough so that the temperature of the oil being treated will not exceed about 95 C.; a satisfactory temperature of the oil during treatment has been found to be about '10 C. 'Ihe dispersed oil trickles downwardly over the packing 68, and is in this manner brought into intimate contact with the rising gas stream, the pressure of the gas created by the blower 78 being suilicient to forcel the gas upwardly through the downwardly flowing stream of oil.

In place of coke-oven gas, Iany other suitable inert gas may be used. Preferably the inert gas should contain little `or no oxygen, since oxygen apparently acts to oxidize certain components of the oil, imparting an undesirable color thereto and raising the coke residue and float tests, and increasing they residue left on distillation at v355 C. It is further preferable that the gas employed should be at a relatively lowtemperature so that the oil'will not become unduly heated and polymerization of certain components effected by the increased temperature. 'In general, as in the case of coke-oven gas, the temperature of the gas contacted with the oil should be so low that the temperature of the oil willnot exceed about While, as previously indicated, the gas used should preferably be a low temperature inert.

gas, other gases such as air or steaml may be used under certain circumstances. If, for example, the creosote oil being treated is of a type which is not sensitive to oxidation or if the oil gives originally a very low test for coke residue, and low float test on the residue at 355 C. so that a substantial increase' in these tests is permissible before exceeding a given specication, or

if the oil is to be used for a purpose where a high coke residue and high-oat test are not objectionable, air may be used for blowing the oil with consequent reduction in the light oil and water content of the creosote oil. Further, if -the oil is of a type containing but a small amount of constituents polymerized at high temperatures, or if a high coke residue and high float test are permissible, steam may be used for blowing the oil. In the preferred embodiment of my invention, however, the gas used for treating the creosote oil is a low temperature inert gas which will not act to oxidize or polymerize constituents inthe oil.

Where the temperatures of the available gas and of the oil to be treated are so low that an excessive volume of gas would be required per gallon of oil to remove a desired amount of volatile material, or to eiect a desired increase in` flash point, the oil or the gas or both oil and gas may be heated.

During the contact of the inert gas and the oil, the water and light oil constituents are taken up by lthe gas and pass out of the tower therewith through the gas conduit 81. The coke-oven gases, at a temperature of for example about 50 C. and carrying the low boiling constituentsare discharged back into the main gas line of the byproduct recovery system, preferably at a point just ahead of the benzol absorber 20. The oil, stripped of detrimental quantities of water and light oil constituents, runs out of the base of the tower, and flows preferably by gravity into the oil storage tank 74. Since the exit gas from the blowing tower containing thev light constituents removed from the oil is discharged back into the main gas line of theby-product recovery system at a point ahead of the benzol absorber, such gas is again conducted through the benzol absorbers, and the light oil constituents picked up in the tower are removed by the customary scrubbing operation in the benzol absorber. The invention thus provides a process for removing water and low boiling constituents from creosote oil, and also for the subsequent recovery of such low boiling constituents thus stripped from the creosote oil.

The following is a specific example of the invention showing the results obtained by blowing creosote oil with coke-oven gas. temperature of which in passing through the blower was raised to approximately 85 C., entered the tower at substantially this temperature, and leftthe tower at approximately 50 C. An

average of 400 cu. ft. of gas per gallon of oil was used:

Untreated oil Treated oil Water content of oil 0. 8% 0. 7l? Spec.. grav. 38 C 1.046' 1.0560 Distillatlon 210 C 4.5% 1.5917 Di=tillati0n 235 C 21. 6% 18.3% Residue at 355 C 19.3 18.9 Float test at C. on residue at 355 C 37 se. 39 secs Coke residue 1. 69% l. 79% Flash point (Pensky-Martin) 152 F. 192

The gas, the

I claim 1. The method of refining creosote oilv which comprises treating the oil with an inert gas, and maintaining the temperature of the inert gas such that during the treatment of the oil the temperature thereof is not increased to exceed substantially C.

2. The method of refining creosote oil which comprises treating the oil with an inert gas, and maintaining the temperature of the inert gas such that during the treatment of the oil the temperature thereof is not increased to exceed substantially 70 C.

3. The method of raising the flash point" of creosote oil containing low boiling constituents which comprises blowing the oil with coke-oven gas under such conditions that during the treatment of the oil the temperature thereof is not increased to exceed substantially 70 C.

4. The method of removing low boiling constituents from creosote oil which comprises passing a stream of coke-oven gas through the oil, the temperatures of the coke-oven gas and of the oil being such that during the treatment of the oil the temperature thereof is not increased to exceed substantially 95 C.

5. The method of removing low boiling constituents from creosote oil which comprises dispersing a body of the oil, and passing in countercurrent relation through the dispersed oil a stream of coke-oven gas, the temperatures of the coke-oven gas and of the oil being such that during the treatment of the oil the temperature thereof is not increased to exceed substantially 95 C.

6. The method -of refining creosote oil containing low boiling constituents which comprises treating the oil with an inert gas, under such conditions that during the treatment of the oil the temperature thereof is not increased to exceed substantially 95 C., separating the oil and the inert gas, and recovering the low boiling constituents from the inert gas.

7. The method of refining creosote oil containing low boiling constituents which comprises treating the oil with coke-oven gas, under such conditions that during the treatment of the oil the temperature thereof is not increased to exceed substantially 95 C., separating the oil and the coke-oven gas, and recovering the low boiling oil constituents from the gas.

8. The method of removing low boiling constituents from creosote oil which comprises dispersing a body of the oil, and passing in countercurrent relation through the dispersed oil a stream of coke-oven gas, under such conditions that during the treatment of the oil the tem-A perature thereof is not increased to exceed substantially 95 C., and recovering the low boiling oil constituents from the gas.

9.- The method of removing low boiling constituents from creosote oil which comprises withdrawing gas from a coke oven by-product recovery process including a light oil absorption stage at a point subsequent to the light oil absorption stage, treating the creosote oil with the said gas, separating the oil and the gas, and passing the gass through the light oil absorption stage, where-by the light oil constituents removed from the oil by the gas are recovered in the light oil absorption stage.

10. The method of removing low boiling constituents from creosote oil which comprises withdrawing gas from a coke ovenfby-product recovery process including a light oil absorption stageat a point subsequent to the light oil absorption stage, treating the creosote oil with the said gas,r

to the said process at a point ahead of the light I oil absorption stage, and passing the gas through the absorption stage whereby the light oil constituents removed from the oil by the gas are recovered in the light oil absorption stage.

11. The method of removing low boiling constituents from creosote oil which comprises withdrawing gas from a. coke oven by-product recovery process including a light oil absorption stage at a point subsequent to the light oil absorption stage, passing the gas in counter-current relation through the creosote oil, the temperature of the gas being such that during the treatment of the oil, the temperature thereof is not increased to exceed substantially 95 C., returning the gas to the said process at a, point ahead of the light oil absorption stage, and passing the gas through the absorption stage whereby the light oil constituents removed from the oil by the gas are recovered in the light oil absorption stage.

12. The method of removing low boiling constituents from creosote oil which comprises withdrawing gas from a coke oven by-product recovery process including a light oil absorption stage at a point subsequent to the light oil absorption stage, dispersing a body of the creosote oil, passing the gas in counter-current relation through the dispersed oil, the temperature of the gas being such that during the treatment of the oil, the temperature thereof is not increased to exceed substantially 70 C., returning the gas to the said process at a point ahead of the light oil absorption stage, andpassing the gas through the absorption stage whereby the light oil constituents removed from the oil are recovered in the light oil absorption stage.

13. The method of operating a coke oven byproduct recovery system which comprises treating one portion of the coke-oven gas to recover tar and light oil lconstituents therefrom, whereby a coke-oven gas is produced substantially free of tar and light oil constituents, utilizing another portion of the coke-oven gas for distillation of tar by direct contact with said tar, recovering a creosote oil fraction from the volatile products of said tar distillation,4 andrening said creosote oil fraction by passing a quantity of said lightoil-free coke-oven gas in surface contact with said oil whereby low boiling constituents present in said oil are removed therefrom as vapor by said gas.

14. The method of operating Aa coke oven byproduct recovery process including a light oil absorption stage which comprises treating one portion of the coke-oven gas to recover tar and light oil constituents therefrom, whereby a cokeoven gas is produced substantially free of tar and light oil constituents, utilizing another portion of the coke-oven gas yfor distillation of tar by direct contact with the said tar, recovering a creosote oil fraction containing substantial amounts of low boiling constituents from the volatile products of said tar distillation operation, refining said creosote oil fraction by passing a quantity of said light-oil-freecoke-oven gas in surface contact with said oil whereby law boiling constituents present in said oil are removed therefrom as vapor by said gas, under such conditions that during treatment of the oil the temperature thereof is not increased to exceed subthe gas are recovered in th light oil absorption stage.

l5. 'I'he method of operating a coke-oven byproduct recovery system which comprises utilizing all or a portion of the foul gases generated in the coking chambers for distillation of tar by direct contact with tar, recovering a creosote oil fraction from the volatile products of said tar distillation, combining the uncondensed gases resulting from said tar distillation with any remaining foul gases not utilized in said tar distillation, treating the combined gases to recover tar and light oil constituents therefrom, and refining said creosote oil fraction by passing a quantity of said light-oil-free coke oven gas in surface contact with said oil whereby low boiling constituents present in said oil are removed therefrom as vapor by said gas.

16. The method of operating a coke-oven byproduct recovery process including a light oil absorption stage which comprises utilizing all or a portion of the foul gases generated in the coking chamber for distillation of tar by direct contact with tar, recovering a creosote oil fraction containing substantial amounts of low boiling constituents from the volatile products of said tar distillation operation, combining the uncondensed gases resulting from said tar distillation operation with any remaining foul gases not utilized in said tar distillation, treating the combined gases to recover tar and light oil constituents therefrom, and rening said creosote oil fraction by passing a quantity of said light-oil-free coke-oven gas in surface contact with said oil whereby low boiling constituents present in said oil are removed therefrom as vapor by said gas, under such conditions that during treatment of the oil the temperature thereof is not increased to exceed substantially 70 C., and reintroducing the gas after treatment of the oil into the said process ahead of the light oil absorption stage, whereby the light oil constituents removed from the oil by the gas are-recovered in the light oil absorption stage. GREGORY E. MCCLOSKEY.

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