US3501398A

US3501398A - Method for improving the efficiency of a multiple-stage phenol extraction process

Info

Publication number: US3501398A
Application number: US733165A
Authority: US
Inventors: Roland L Menzl; Fred W Schuessler
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1968-05-29
Filing date: 1968-05-29
Publication date: 1970-03-17
Anticipated expiration: 1987-03-17

Description

March 17, 1970 Nz ETAL 3,501,398

METHOD FOR IMPROVING THE EFFICIENCY OF A MULTIPLE-STAGE PHENOL EXTRACTION PROCESS Filed May 29, 1968 4 Sheets-Sheet 1 F incl 0 Raff/note F lg. 1

*CONTACTOR Secondary Raff m: 2 SEPARATOR I i V -0ONTAGTOR Distillate 25-- Final Extract INVENTORS.

Roland L. Menz/ BY Fred W. Schuess/er mzm'aw ATTORNEY March 17, 1970 ME ErAL METHOD FOR IMPROVING THE EFFICIENCY OF A MULTIPLE-STAGE PHENOL EXTRACTION PROCESS Filed May 29, 1968 4 Sheets-Sheet 2 R w s a ma e Phenol g;

2.9 .Secapdary Rafflnafe --CONTACTOR 36 40 EPARATORS- 35 I --CONTACTOR DisfiI/afe 1 Final Extract x9442 A TTOR/VEY March 17, 1970 MENZL ETAL 3,501,398

METHOD FOR IMPROVING THE EFFICIENCY OF A MULTIPLE-STAGE PHENOL EXTRACTION PROCESS Filed May 29, 1968 4 Sheets-Sheet 5 52 Pnena/ F lg. 3

5/ Final Phenol I L Raff/note Oisfi/lafe f 48 CONTACTORS Extract Extract Fig. 4

7 Phenol Final CONTACTOR 55 59 5-8 Raff/note 57- #CONTACTOR Disfi/lafe 5.9- I Final Exfracf 60 H 0 INVENTORS.

2 Roland L. Menz/ BY Fred W. .Scnuess/er March 17, 1970 R. L. MENZL ET L 3,501,398

METHOD FOR IMPROVING THE EFFICIENCY OF A MULTIPLE-STAGE PHENOL EXTRACTION rnocnss Filed May 29, 1968 4 Sheets-Sheet 4 Fig. 5

? Phenol 75 Final 64 f 67 Raff/note CONTACTOR 69 zCONTACTOR Distillate 4 Final Extract Secondary 7/ Raff/note 73 -SEPARATOR INVENTORS. Roland L. Menz/ BY Fred W. Schuess/er United States Patent O US. Cl. 208-316 9 Claims ABSTRACT OF THE DISCLOSURE The method comprises adding continuously a small amount of water to the intermediate-extract stream which flows between two serially-connected contactors. The added water decreases the solvency of the phenol in the intermediate-extract stream to release secondary-rafiinate material. The secondary-raffinate material is separated from the intermediate-extract stream and is withdrawn as a product. Subsequently, the remainder of the stream is heated to a temperature between about 150 F. and about 200 F. prior to being introduced into the succeeding contacting zone. The added water is an amount that will bring the water content of the phenol-rich phase to a level thatis within the range of about 1 weight percent to about 12 weight percent, based on the total amount of phenol being added to the process.

BACKGROUND OF THE INVENTION Lubricating oil fractions can be obtained from a petroleum crude oil. Such fractions contain not Only the desired high viscosity index hydrocarbons, isoparafilns and cyclic compounds with long paraflinic side chains, but also undesirable highly condensed cyclic compounds of low viscosity index, polycyclics with no or only short side chains, and heterocyclics which reduce the oils stability. The undesirable constituents are selectively removed from the oil by means of solvent extraction processes. These solvent extraction processes include the furfural, phenol, Duo-Sol, Edeleanu, Chlorex, and nitrobenzene processes.

Fundamentally, all of the above-mentioned processes are similar. In each, the oil is contacted with a selective solvent that extracts the undesirable components and, subsequently, the solvent is separated from the extract and rafiinate streams. The solvent causes the hydrocarbon stream to separate into two phases, a first phase consisting primarily of solvent in which are dissolved the extracted objectionable bodies, such as polycyclic aromatics, and a second phase consisting of the refined oil saturated with the solvent. The primary purpose of each process is to improve the quality of the lubricating oil distillate being treated by selectively removing the undesirable components therefrom, thereby improving the viscosity index and ability to resist oxidation of the distillate. Such separation of lubricating oil hydrocarbons is entirely physical. The yields of such a process vary with the efiiciency of the solvent and the efiiciency of the process itself.

A suitable solvent extraction process for the treating of lubricating oil distillates is the process which employs phenol as the solvent. In such a process, countercurrent contactors may be connected in series and an increase in the number of countercurrent contacting stages reduces solvent requirement and improves the selectivity of the process. The economics of the extraction process are highly dependent on the quantity of solvent required in the process in view of the high cost of solvent recovery. Therefore, a desirable phenol extraction system may comprise at least two contactors wherein the hydrocarbon fraction to be treated is charged to the contactor that is a one end of the serially-connected chain of contactors while the phenol solvent is charged into the contactor that is at the other end of the chain of contactors. There has now been found a method for improving the eflic1ency of a phenol extraction process wherein at least two contactors are connected in series. In addition, an intermediate viscosity-index product of commercial value is recovered, which would otherwise remain in the lowvalue extract oil.

SUMMARY OF THE INVENTION Briefly, in accordance with the invention, there is provided a method for improving the efficiency of a phenol extraction process wherein a lubricating oil distillate stream is treated to improve its color, ability to resist oxidation, and viscosity index and wherein a first contacting zone is serially connected to a second contacting zone so that phenol is charged to and a final-raflinate stream is withdrawn from said first contacting zone, an intermediate-extract stream is passed from said first contacting zone to said second contacting zone, an intermediaterafiinate stream is passed from said second contacting zone to said first contacting zone, and said distillate stream is charged to and a final-extract stream is withdrawn from said second contacting zone. The first contacting zone is operated at a temperature within the range of about 130 F. to about 170 F. The second contacting zone is operated at a temperature within the range of about 150 F. to about 200 F. The method comprises adding continuously a small amount of water to the intermediate-extract stream to decrease the solvency of the phenol that is in said intermediate-extract stream to release secondary-raifinate material, separating and withdrawing said secondary-ratfinate material as a product from said intermediate-extract stream, and heating said intermediate-extract stream to a temperature within the range of abou 150 F. to about 200 F. prior to intro ducing said intermediate-extract stream into said second contacting zone.

The small amount of water that is added continuously is an amount that will increase the water content of the phenol-rich phase of the intermediate-extract stream to a level within the range of about 1 weight percent to about 12 weight percent, based on the total amount of phenol being added to the process. Preferably, the small amount of water is an amount that will bring the water content to a level that is within the range of about 2 weight percent to about 6 weight percent, based on the total amount of phenol being added to the process.

It is known that a reduction in temperature increases:

the selectivity of the phenol solvent, that is, the concen tration of undesirable compounds in the oil portion of the extract is increased. Advantageously, the intermediate-extract stream is passed through a cooler to cool the intermediate-extract stream to a temperature that is within the range of about 70 F. to about F., the. cooler being placed in the process scheme to treat thev intermediate-extract stream prior to the withdrawing of the secondary-railinate material from the intermediateextract stream.

DESCRIPTION OF THE DRAWINGS The accompanying drawings are presented to enable the reader to obtain a better understanding of the present invention.

FIGURE 1 is a simplified schematic drawing of a phenol extraction process which comprises two serially-connected phenol-extraction contactors and which employs an embodiment of the present invention.

FIGURE 2 is a simplified schematic drawing of a phenol extraction process which comprises two serially- 3 connected contactors and which employs another embodiment of the present invention.

FIGURE 3 is a simplified schematic representation of a phenol extraction system comprising two serially-connected contacting zones wherein one-half of the solvent employed is introduced into each of the contacting zones and the lubricating oil distillate to be treated is'introduced into only one.

FIGURE 4 is a simplified schematic drawing of a process employing an embodiment of the present invention wherein solvent is added to only one of two seriallyconnected contacting zones and water is introduced to the intermediate-extract stream being withdrawn from the contacting zone to which the phenol is added.

FIGURE 5 is a simplified schematic drawing of a process employing an ambodiment of the present invention wherein the intermediate-extract stream passing between two serially-connected contacting zones is cooled, water is added to the stream, a secondary-rafiinate stream is withdrawn, and the remainder of the intermediate-extract stream is passed to the succeeding contacting zone.

In the above simplified drawings, auxiliary equipment such as pumps, valves, and the like, are not shown. In addition, solvent recovery equipment is not shown. Such items and their use and location are well known to those people having ordinary skill in the art.

DISCUSSION AND SPECIFIC EMBODIMENTS In a phenol extraction process wherein lubricating oil fractions of a petroleum crude are treated to provide lubricating oils having improved viscosity indexes, improved color, and improved ability to resist oxidation, an increase in the temperature increases the solvency of the phenol solvent, resulting in more oil being dissolved in the phenol. However, as was pointed out above, an increase in temperature also reduces the selectivity of the phenol solvent. Moreover, an increase in the number of contacting stages will reduce solvent requirement and will improve the selectivity of the process. Since water affects the solubility of hydrocarbons in phenol, water is often added to a phenol extraction process to control the solubility of the hydrocarbons. An increased water content reduces the solvency of the solvent.

The efiiciency of a phenol extraction process can be improved through an increase in the number of contacting stages in the process. Therefore, a process that employs serially-connected contacting zones is, in general, more efficient than a phenol extraction process that has only one contacting zone. In a phenol extraction process which employs two contacting zones that are connected in series, the hydrocarbon stream to be treated is introduced into one of the contacting zones while the phenol solvent is introduced into the other. Final raffinate, i.e., the desired product having improved properties, is withdrawn from that contacting zone into which the phenol solvent is charged. An intermediate-extract stream is withdrawn from this particular contacting zone and is passed into the con tacting zone into which the hydrocarbon stream is introduced. A final-extract stream is withdrawn from this latter contacting zone. In addition, an intermediate-rafiinate stream is withdrawn from this latter contacting zone and is passed into the contacting zone into which the phenol is introduced.

Improved operation of a serially-connected two-zone process is achieved, according to the present invention, when water is introduced into the intermediate-extract stream. This intermediate-extract stream containing increased amounts of water is passed into and through a separation zone. While it is in the separation zone, the hydrocarbons having intermediate viscosity indexes are released from the phenol and form a separate layer. This separate layer is withdrawn as a secondary rafiinate stream. Its viscosity index and other properties are sufficient to enable it to be used as a commercial product. The remainder of the intermediate-extract stream is heated to the temperature required for efficient operation of the second contacting zone and then passed into the second contacting zone. For most efficient operation, the intermediate-extract stream may be cooled prior to its separation into two layers.

The principle that an increase in temperature increases the solvency of the phenol is used advantageously in the present invention. For example, the intermediate-extract stream that is withdrawn from a first contacting zone is heated to a temperature as high as 190 F. prior to its introduction into the ,second contacting zone of seriallyconnected Zones and the second contacting zone is maintained at this elevated temperature to improve the ability of the phenol to dissolve hydrocarbons. Therefore, more efficient extraction occurs in the second contacting zone, so that the final extract that is withdrawn from the second contacting zone contains increased amounts of the undesired components of the lubricating oil fraction being treated.

In addition, the present invention advantageously uses the principle that water reduces the solvency of the phenol solvent. For example, the introduction of water into the intermediate-extract stream passing between the two contactors enables the phenol solvent to release some of the hydrocarbons that have an intermediate viscosity index and that have been dissolved in the phenol during its passage through the first contacting zone. These released hydrocarbons are separated from the intermediate-extract stream and are withdrawn as usable secondary-rafiinate material.

The production of the secondary-rafiinate material can be increased by cooling the intermediate-extract stream in addition to the use of water as a means of promoting separation of the more-paraffinic hydrocarbons i.e., com pounds with a high ratio of carbon atoms in side chains to carbon atoms in rings, from the intermediate-extract stream. This is another example of the application of the principle that an increase in temperature increases the solvency of the phenol, or stated differently, a decrease in temperature decreases the solvency of the phenol.

Typical lubricating oil fractions that are treated in a phenol extraction process employing the present invention are petroleum hydrocarbon fractions boiling within the range of about 750 F. to about l,050 F. at atmospheric pressure. Such fractions possess at 210 F. a viscosity within the range of about 35 SUS to about SUS. These hydrocarbon fractions may be waxy or may be dewaxed. Such feedstocxs will provide oils which meet the viscosity specifications established for 5 to 50 SAE grade oils.

Commercial grades of phenol are employed in the phenol extraction process. It is most desirable to introduce a relatively anhydrous phenol stream into the first contacting zone in a phenol extraction system employing two contacting zones. The use of a relatively anhydrous phenol stream in the first contacting zone provides more efiicient use of the water being added to the intermediate-extract stream.

It has been found that introducing water with the phenol into the contacting zone will not provide maximum efficiency. A greater improvement will be attained in a twocontacting-zone phenol extraction process, if a major portion of the small amount of water that is added to the process is added to the intermediate-extract stream that is passing between the two serially-connected contacting zones. To provide maximum separation of the desired more-paraifinic hydrocarbons from the other hydrocarbons that are present in the intermediate-extract stream, the intermediate-extract stream should be cooled prior to the addition of the water thereto. It has been found that maximum efiiicency can be achieved, if the small amount of water that is added to the intermediate-extract stream is an amount that will increase the water content of the phenol-rich phase of that stream to a level that is within the range of about 1 weight percent to about 12 weight percent, based on the total amount of phenol that is being charged to the process. Preferably, the amount of water is an amount that will increase the water content to a level that is within the range of about 2 weight percent to about 6 weight percent, based on the total amount of phenol being charged to the process.

The following figures and examples demonstrate the operability and advantages of various embodiments of the invention.

FIGURE 1 provides a simplified schematic diagram of a phenol extraction process which comprises two seriallyconnected contacting zones and which employs an embodiment of the present invention. The contacting zones may be either extraction towers (gravimetric contactors) or centrifugal contactors, or a mixture of both. For the purposes of this discussion, the contacting zones are shown as extraction towers.

In the processing scheme of FIGURE 1, contacting zones 11 and 12 are connected in series. Phenol is introduced into contacting zone 11 near its top by way of line 13. Distillate is charged to contacting zone number 12 near its bottom by way of line 14. Contacting zones 11 and 12 are connected by line 15 through which an intermediate-raifinate stream passes from the top of contacting zone 12 to contacting zone 11 near its base. An intermediate-extract stream is withdrawn from contacting zone 11 near its base by way of line 16. This intermediate extract stream is passed through cooler 17 and line 18.

The intermediate extract being withdrawn from contacting zone 11 is at a temperature within the range of about 130 F. to about 170 F., the temperature being maintained in contacting zone 11. This material is cooled by cooler 17 to a temperature within the range of about 70 F. to about 120 F. Since a decrease in temperature decreases the solvency of the phenol, the cooling of the extract will cause the release of some of the less soluble hydrocarbons therefrom, namely, the more-parafiinic hydrocarbons. The water is introduced into the cooled extract in line 18 via line 19. The addition of water tends to reduce the solvency of the phenol. This provides further impetus for the release of more of the less-soluble hydrocarbons.

The intermediate-extract stream in line 18 is passed into separator 20 wherein the released hydrocarbons are separated from the solvent phase. The released or sprung hydrocarbons are withdrawn from separator 20 via line 21 asa secondary-ratfinate stream. The stream is an inl termediate-viscosity-index product having commercial value. The solvent phase is withdrawn from separator 20 by way of line 22 and is passed through heater 23 and line 24 into contacting zone 12. The solvent phase is heated by heater 23 to a temperature that is within the range of about 150 F. to about 200 F., the temperature being employed in contacting zone 12. The increase in temperature improves the solvency of the phenol to compensate for the loss of solvency brought about by the water addition to the solvent. Final extract is withdrawn from the bottom of contacting zone 12 by way of line 25. Final rafiinate is withdrawn from the top of contacting zone 11 via line 26. Both the final-raflinate and secondary-raffinate streams possess improved viscosity indexes improved color, and improved ability to resist oxidation and are, therefore, satisfactory usable products.

FIGURE 2 provides a simplified schematic diagram of a phenol extraction process comprising two serially-connected contacting zones and employing another embodiment of the present invention. In this process scheme, the cooled intermediate-extract stream is separated in a twostage separating zone.

With reference to FIGURE 2, contacting

zones

27 and 28 are connected in series. Relatively anhydrous phenol is introduced into contacting zone 27 by way of line 29. Distillate is charged to contacting zone 28 near its base by way of line 30. Contacting

zones

27 and 28 are connected by line 31 through which an intermediate-raffinate stream is passed from the top of contacting zone 28 to contacting zone 27 near its base. Intermediate extract is withdrawn from contacting zone 27 near its base by way of line 32. This intermediate extract is passed through cooler 33 and line 34 into separator 35, the first stage of a multiple-stage separating zone. The temperature of the intermediate-extract stream is cooled from "a temperature within the range of about F. to about 170 F., the temperature within contacting zone 27, to a temperature within the range of about 70 F. to about 120 F. In separator 35, the hydrocarbons released as a result of the cooling of the intermediate-extract stream are separated from the intermediate-extract phase and are withdrawn from separator 35 and returned to contacting zone 27 by way of line 36. The intermediate-extract phase is withdrawn from separator 35 via line 37. Water is introduced by way of line 38 into the intermediate-extract phase that is withdrawn from contacting zone 35. The water-bearing intermediate-extract phase is passed into separator 39, the second stage of the multiple-stage separating zone. The addition of the water results in further release of less-soluble hydrocarbons from the intermediate-extract phase and these less-soluble hydrocarbons are separated from the intermediate-extract phase and are withdrawn from separator 39 by way of line 40 as a secondary-raflinate stream. The remaining intermediateextract material is withdrawn from separator 39' near its base and passed through line 41 into heater 42. The temperature of the intermediate-extract phase is increased to a level that is within the range of about F. to about 200 F. This temperature range is the temperature range that is being maintained in contacting zone 28. Heated intermediate-extract material is passed through line 43 into contacting zone 28 near its top. The heating of the remaining intermediate-extract material increases the solvency of the phenol in the intermediate-extract material to compensate for the etfect of its water content on the solvency of the phenol. Final extract is withdrawn from the bottom of contacting zone 28 by way of line 44 while final rafiinate material is withdrawn from contacting zone 27 at its top by way of line 45. Both the secondary-raffinate and final-trafiinate material posse ss desired viscosity indexes, color, and improved ability to resist oxidation and, therefore, are recovered as usable lubricating oil products.

Data presented for the process schemes represented in the following examples were obtained in laboratory equipment in batch operations. These examples demonstrate advantages of the present invention.

EXAMPLE I In this example, two small-scale contactors are employed, as schematically represented in FIGURE 3 by contacting zones, or contactors, 46 and 47. An MP10 dewaxed distillate is charged to contacting zone 46 near its base by way of line 48. This distillate has a viscosity of 214 SUS at 100 F. and a viscosity of 45.6 SUS at 210 F. Its viscosity index is 72. The fresh solvent-to-oil ratio used in this process is 2.5 :1. The extraction temperature employed is 150 F. One-half of the total phenol solvent used in this example is charged to contacting zone, on contactor, 46 near its top via line 49. This fresh phenol solvent contains 6 percent water. Extract is withdrawn from contactor 46 at its bottom by way of line 50. This extract is discarded. Intermediate raflinate is withdrawn from contactor 46 near its top via line 51 and is passed into contactor 47 near its bottom by way of line 51.

One-half of the solvent employed in this example is charged to the top of contactor 47 by way of line 52. This phenol stream contains 1.9 percent water, based on the phenol. Extract is withdrawn from contactor 47 at its bottom via line 53. Final-rafiinate is withdrawn from contactor 47 near its top via line 54. The extraction yield of this example is 58.7 weight percent and the Viscosity index of the final-rafiinate is 96.

7 EXAMPLE II The process scheme of this example is schematically represented in FIGURE 4. The distillate charged to the process of this example is the same as that employed in Example I. The fresh-solvent-to-oil ratio is 1.25:1. The extraction temperature is 150 F. The distillate is charged to contactor 55 near its bottom via line 56. Intermediate raffinate is withdrawn from contactor 55 via line 57 and is passed by way of line 57 into contactor 58 1 near its bottom. Intermediate extract is withdrawn from contactor 58 at its bottom via line 59. The water content of the phenol in this intermediate-extract stream is raised to 6 percent by adding water via line 60 and the intermediate-extract stream having this 6 percent water level is passed into contactor 55 by way of line 59. Final extract is withdrawn from contactor 55 via line 61. Fresh phenol solvent is introduced into contactor 58' by way of line 62. This phenol contains 1.9 percent water and is equal in'amount to one-half the amount of solvent employed in Example I. Final raifinate is withdrawn from contactor 58 near its top via line 63. This final raflinate provides an extraction yield of 75.4 weight percent and possesses a viscosity index of 82.

Use of the extraction scheme employed in Example II, wherein only one-half of the amount of solvent that was used in Example I is employed, provides an improved extraction yield of material, but with a' lower viscosity index than that of the product obtained in Example 1.

EXAMPLE IH In this example, the process scheme represented in FIGURE 5 is employed. This process scheme employs an embodiment of the present invention.

A portion of the same distillate employed in Example I is employed in this example. The fresh-'solvent-to-oil ratio that is employed herein is 1.25:1 and the extraction temperature is 150 F.

Distillate is charged to contactor 64 near its bottom by way of line 65. Intermediate rafiinate is withdrawn from contactor 64 via line 66 and is passed via line 66 into contactor 67 near its bottom. Fresh phenol solvent is introduced into contactor 67 at its top via line 68. This phenol contains 1.9 percent water. A final-raffinate stream is withdrawn from contacting zone 67 near its top via line 69 while an intermediate-extract stream is withdrawn.

from contacting zone '67 at its bottom via line 70. This intermediate-extract stream is passed via line 70 into separator 71. The water level of this intermediate extract is raised to 6 percent, based on the phenol charged, by the addition of water via line 72. The intermediate-extract phase, now at a temperature of about 80 F., is permitted to stratify into two layers. The top layer, being a second- 7 ary raffinate, is withdrawn from separator "71 via line 73. The bottom layer, being extract, is withdrawn as intermediate extract from separator 71 by line 74 and is passed through line '74, heater 75, and line 76 into contactor 64 near its top. The intermediate extract is heated to 150 F. prior to its introduction into contactor 64. A final-extract stream is withdrawn from contactor 64 at its bottom by way of line 77.

The amount of phenol solvent that is charged in this example is one-half of the amount of solvent that was employed in Example I. The final raffinate provides an extraction yield of '61.0 weight percent and has a viscosity index of 94. The secondary raflinate furnished ayield of 9.5 weight percent and posseses a viscosity index of 78.

Consequently, the total saleable product of this example is 1 onstrates the improved efficiency that can be obtained when the present invention is employed.

8 EXAMPLE IV weight percent and possesses a viscosity index of 94.

In this example, which is another embodiment of the present invention, the same amount of fresh solvent that was used in Example I was employed. The same overall yield of saleable product was obtained. However, 74.6v

percent of this product showed a viscosity index which was 5 units higher than that of the product of Example I, while 25.4 percent of the saleable product showed a viscosity index that was lower by only 2 units.

EXAMPLE V In this example, the process scheme described in Example III is used. However, in this example a waxy 10 distillate is employed as the material to be treated. This waxy distillate possesses a viscosity of 179 SUS at F. and a viscosity of 44.4 SUS at 210 F. The viscosity index of this waxy distillate is 85.

The final rafiinate provides an extraction yield of 66.5 weight percent and, upon dewaxing, possesses a viscosity index of 95. The secondary raflinate furnishes a yield of 7.5 weight percent and, when dewaxed, possesses a viscosity index of 95.

The above examples provide results which demonstrate that the addition of water to the intermediate-extract stream and the subsequent separation of oil from this extract stream and heating of the remaining extract stream prior to its use in a subsequent serially-connected contacting zone provides increased yields of distillate material possessing improved viscosity indexes.

The above examples and figures are presented for the purpose of illustration only and are not intended to limit the scope of the invention.

What is claimed is:

1. A method for improving the efficiency of a phenol extraction process wherein a lubricating oil distillate stream is treated to improve its color, ability to resist oxidation, and viscosity index and wherein a first contacting zone is serially connected to a second contacting zone so that phenol is charged to and a final-rafiinate stream is withdrawn from said first contacting zone, an intermediate-extract stream is passed from said first contacting zone to said second contacting zone, and intermediateraflinate stream is passed from said second contacting zone to said first contacting zone, and said distillate stream is charged to and a final-extract stream is withdrawn from said second contacting zone, said first contacting zone being operated at a temperature within the range of about F. to about 170 F. and said second contacting zone being operated at a temperature within the range of about F. to about 200 R, which method comprises adding continuously a small amount of water to said intermediate-extract stream to decrease the solvency of the phenol that is in said intermediateextract stream to release secondary-rafiinate material,

separating and withdrawing said secondary-rafiinate material as a product from said intermediate-extract stream, and heating said intermediate-extract stream to a temperaturewithin the range of about 150 F. to about 200 F. prior to introducing said intermediate-extract stream into said second contacting zone. 1

2. The method of claim l wherein said small amount of water is an amount that will increase the water content of the phenol-rich phase of said intermediate-extract stream to a level that is within the range of about 1 weight percent to about 12 weight percent, based on the-total amount of phenol being added to'the process.

.3. The method of claim 1 wherein said small amount of water is an amount that will increase the water content of the phenol-rich phase of said intermediate-extract stream to a level that is within the range of about 2 weight percent to about 6 weight percent, based on the total amount of phenol being added to the process.

4. The method of claim 1 wherein said intermediateextract stream is passed through a cooler to cool said intermediate-extract stream to a temperature that is within the range of about 70 F. to about 120 F., said cooler being placed to treat said intermediate-extract stream prior to said withdrawing of said secondary-raffinate material from said intermediate-extract stream.

5. The method of claim 4 wherein said cooler is placed to treat said intermediate-extract stream prior to said adding of said small amounts of water.

6. The method of claim 4 wherein said small amount of water is an amount that will increase the water content of the phenol-rich phase of said intermediate-extract stream to a level that is within the range of about 1 weight percent to about 12 weight percent, based on the total amount of phenol being added to the process.

7. The method of claim 4 wherein said small amount of water is an amount that will increase the water content of the phenol-rich phase of said intermediate-extract stream to a level that is within the range of about 2 weight percent to about 6 weight percent, based on the total amount of phenol being added to the process.

8. The method of claim 5 wherein said small amount of water is an amount that will increase the water content of the phenol-rich phase of said intermediate-extract stream to a level that is Within the range of about 1 Weight percent to about 12 weight percent, based on the total amount of phenol being added to the process.

9. The method of claim 5 wherein said small amount of water is an amount that will increase the water content of the phenol-rich phase of said intermediate-extract stream to a level that is within the range of about 2 weight percent to about 6 weight percent, based on the total amount of phenol being added to the process.

References Cited UNITED STATES PATENTS 2,178,321 10/1939 Clarke 208335 2,344,406 3/ 1944 Hibshman 208324 2,773,005 12/1956 Meyer et a1. 208324 2,846,354 8/1958 Holm et al. 208335 HERBERT LEVINE, Primary Examiner US. Cl. X.R. 208317, 324, 335