Patent Publication Number: US-10767115-B2

Title: Methods and apparatus for clarification of pyrolysis oils

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of U.S. patent application Ser. No. 15/717,264 filed Sep. 27, 2017 entitled “Methods and Apparatus for Clarification of Pyrolysis Oils”, the disclosure of which is expressly incorporated herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to methods and apparatus for converting the black color of pyrolysis oil derived from thermal treatment of vehicle tires or other waste materials to a lighter more yellow color. It also relates to methods and apparatus for removing polar compounds from pyrolysis oil and reducing the polyaromatic hydrocarbons (PAH) levels in the pyrolysis oils. 
     2. Description of the Prior Art 
     It has been known to employ methods of pyrolysis of hydrocarbon materials such as waste vehicle tires to produce useful byproducts. This not only minimizes the problem of huge accumulations of discarded tires, but produces economically worthwhile products. See U.S. Pat. No. 6,833,485, for example. The pyrolysis process may produce a carbon product, a liquid hydrocarbon product and a combustible gas. 
     U.S. Pat. No. 6,835,861 discloses a low energy method of pyrolysis of hydrocarbon materials which employs a clay and metal catalyst. It produces a solid carbonaceous material, an oil and combustible gas products. The carbon black produced by the recited method was said to contain no detectable PAHs. The carbon char is said to be usable as a source of fuel. High purity carbon blacks were said to be usable for toner and electrical sensors. Liquid oil and gas produced by the method are said to be easily separable from the system. 
     U.S. Pat. Nos. 8,263,038 and 8,512,643 recite a method of devolatilizing recycled carbon black obtained from the pyrolysis of tires by deagglomerating the recycled carbon black to reduce the black particle size and impinging a countercurrent air current on the black particles to increase the processing temperature and enhance release of volatiles. 
     Pyrolysis oil produced by heating rubber, such as tire rubber in the absence of oxygen, produce a black oil which has a strong sulfur and amine odor. Although the oil has an appearance much like crude oil, its composition is substantially different. 
     While both crude oil and pyrolysis oil contain pentane (C5), heptane (C7) and other alkane insolubles, the insolubles from crude oil consist of paraffins and asphaltenes. Insolubles from pyrolysis oil consist of polar compounds such as benzoic acid and oxygenates, sulfur and nitrogen compounds. 
     Tire pyrolysis oil has currently been used as a crude fuel or for down well application in order to clear oil well deposits. It has been known to collect fractions of the oil by distillation, but except for the fractions at the very light ends, the distillates are black and contain an objectionable sulfury/amine odor. It has been suggested that the black color was entrained carbon, however, when filtration was attempted in order to remove the black color, this was not successful. 
     In spite of the known prior art, there remains a very real and substantial need for solutions to the foregoing problems. 
     SUMMARY OF THE INVENTION 
     The method and apparatus of the present invention effectively reduces the undesired black color to a transparent dark amber and preferably to a transparent yellow which is more preferred with light transparent yellow being most preferred. The invention also effects a meaningful reduction in the undesired sulfury/amine odor. Finally, the preferred final product will have a reduction in the level of PAH&#39;s and be under 1 ppm of the PAH Benzo(a)pyrene. 
     The temperature range for removal of solvent from oil or clay residue is from the boiling point of the solvent up to about the boiling point of the oil fraction. For example, for hexane, when being used to process the unfractionated pyrolysis oil, the temperature range would be about 68° C. to 100° C. It has been found that exceeding the upper limit incurs an increase in the cost of the process without providing an offsetting comparable benefit. A preferred temperature range would be between 68° C. and 78° C. and the most preferred temperature range would be between 68° C. and 70° C. 
     In alternate embodiments of the invention, separation may be effected by a distillation column or a wiped film evaporator (WFE) with a jacket or heater heating the hexane, solvent and oil mixture to above the solvent&#39;s boiling point but not above the boiling point of the oil. Another advantage of the embodiments employing the distillation tower or wiped film evaporator is subject to the capacity of the column and evaporator, the operation may be performed on a continuous basis limited only by the capacity of the clay column. 
     It is an object of the present invention to provide a method and apparatus for efficiently clarifying pyrolysis oils. 
     It is a further object of the invention to provide an efficient and economical means for accomplishing such clarification. 
     It is yet another object of the invention to produce the desired transparent yellow color for the processed pyrolysis oil. 
     It is another object of the present invention to produce pyrolysis oil which does not have the objectionable sulfury/amine odor. 
     It is yet another object of the present invention to reduce the amount of PAH present in the processed oil. 
     It is yet another object of the present invention to provide a desirable light yellow color for the pyrolysis oil while eliminating the undesired sulfury/amine odor and reducing the PAHs in order to enhance the commercial value of the processed pyrolysis oil. 
     It is another object of the present invention to provide a system for separating pyrolysis oil from a solvent which is mixed therewith employing a distillation column wherein heating is effected above the boiling point of the solvent. 
     It is yet another object of the present invention to provide a system for separating a solvent which is admixed with pyrolysis oil employing a wiped-film evaporator. 
     In a further embodiment, it is another object of the present invention to provide a method and apparatus for continuous operation subject to the limits imposed by the capacity of column absorbent packing. 
     It is another object of the present invention to provide alternate embodiments which employ either a distillation column or a wiped film evaporator in effecting separation of the nonpolar solvent from the pyrolysis oil. 
     These and other objects of the invention will be readily apparent from the following detailed description and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a form of apparatus employable in the present invention using a distillation-elution method. 
         FIG. 2  is a schematic illustration of a form of apparatus employable in the present invention employing a forced flow-elution method. 
         FIG. 3  is a schematic illustration of another embodiment of the distillation elution apparatus of the present invention employing a wiped film evaporator (WFE). 
         FIG. 4  is a schematic illustration of another embodiment of the distillation-elution apparatus employing a packed column employable in the method of the present invention. 
         FIG. 5  is a plot of weight percent versus temperature versus derivative weight percent showing the relationships in drying clay. 
         FIGS. 6 through 10  are schematic views showing the operation of subunits of the general system shown. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides methods and apparatus for removing the polar compounds. Removal is accomplished by adjustment of conditions such that the polar compounds bind to activated attapulgite which is also known as palygorskite. We have tried a number of other materials without meaningful success. These included but were not limited to bentonite, montmorillonite, activated carbon, charcoal, carbon black and diatomaceous earth, but were not successful in producing the desired result. 
     The invention also contemplates methods and apparatus for regenerating the clay with a polar solvent and then reactivating the same. Reactivation may be accomplished using the same apparatus and methods as for elution, but with the said polar solvent. 
     The method of the present invention involves initially adjusting the polarity of the unfractionated pyrolysis oil or pyrolysis oil fractions, absorption of the contaminants onto clay followed by elution and separation of the clean oil from the adjusting solvent. 
     The polarity may be adjusted by dilution with a nonpolar solvent which may be an alkane or combination of several alkanes. The alkanes may be ones having 4 to 10 carbons (butane, pentane, hexane, heptane, octane, nonane or decane) and preferably pentane, hexane, and heptane (C5-C7) with hexane (C6) being the preferred alkane. If desired, combinations of two or more alkanes may be employed in the method. 
     The unwanted components are absorbed onto the attapulgite. These unwanted components include alkane-insolubles of polar compounds such as benzoic acid, quinolone, steric acid oxygenates, sulfur-containing compounds and nitrogen-containing compounds. The methods and apparatus of the present invention removes the polar compounds. This may be accomplished by precipitation and filtration or centrifugation of insolubles and binding of the polar compounds to activated attapulgite clay. The removal of the polar compound not only removes the black color and undesired odor, but the pyrolysis oil maintains its physical and chemical properties. This is followed by elution of the clean oil in the nonpolar solvent. The solvent is then separated from the oil by evaporation. After that, the column is cleaned for reuse with a polar solvent such as acetone, methanol, tetrahydrofuran or dimethylformamide or other polar solvents, for example. 
     The heavier end of pyrolysis oil is known to contain various poly-aromatic hydrocarbons (PAHs) including benzo(a)pyrene which is the most carcinogenic of this compound group. It has been found that the present invention clarifies the oil color, reduces the odor, and has reduced levels of PAHs. 
     The method of the present invention involves removal, by precipitation and adsorption of the black material from the oil by using an alkane or alkane mixture selected from the group consisting of C4 through C10 (butane, pentane, hexane, heptane, octane, nonane and decane). The preferred alkane is one selected from the group consisting of alkanes C5 through C7 (pentane, hexane and heptane). The most preferred alkane is hexane. 
     The oil to be charged onto the column is diluted with an alkane solvent at a ratio of about 1:2 to 1:30 (oil to alkane) by volume and, preferably, of about 1:4 to 1:15 and, most preferably, of about 1:6 to 1:10. The diluted oil is aged by sitting at room temperature for at least 30 minutes to allow precipitation. The aged diluted oil can be filtered or centrifuged to remove precipitate prior to charging onto the column or it can be charged onto the column without removing precipitate. The oil is charged slowly onto the top of the bed and the fluid is collected from the bottom of the column. For example, this could involve approximately 0.22 liters per hour of column flow per liter of void volume (using a column with approximately 18.2-liter void volume is equivalent to 4 liters per hour column flow). The range of flow rates is about 0.1 to 0.6 liters per hour of column flow per liter of void volume, a preferred range would be about 0.2 to 0.4 liters per hour of column flow per liter of void volume and a most preferred range would be about 0.3 to 3.5 liters per hour of column flow per liter of void volume. 
     The ratio of clay to oil to be clarified is in the range of about 4:1 to 20:1 by weight, or preferably about 6:1 to 15:1 by weight and, most preferably, about 6:1 to 10:1 by weight. The greater weight enhances recovery. 
       FIG. 1  illustrates an alternate method (referred to herein as “distillation-elution method”) of processing the pyrolysis oil which method is slightly preferred over the forced-flow-elution method to be described herein in connection with  FIG. 2 . One advantage over the forced-flow-elution method is that the distillation-elution method uses less solvent and, therefore, can be more advantageously employed economically. 
     While both the methods and apparatus of  FIGS. 1 and 2  will effectively practice the present invention, there is a preference for  FIG. 1 . The distillation-elution method and apparatus (shown in  FIG. 1 ) employs less solvent to elute material from the column in the elution phase and employs less wash solvent in the wash phase, Also, since the column is eluted and washed with distilled solvent, it typically operates at a higher temperature than the forced-flow-elution method. This results in eluting and washing at greater efficiencies. 
     With respect to eluting oil, there are two effective alternate procedures for washing the column. In an example of the first method, hexane is delivered to the top of the bed by means, for example, of a pump and is allowed to migrate down by gravity. The flow is controlled through the columns at approximately 4 liters per hour washing the bed with up to 30 bed volumes using a valve at the bottom of the column. The eluent contains extracted oil and hexane. The oil and hexane is collected in a vessel and separated from each other by distillation at a temperature sufficient to evaporate hexane (68° C.), but not high enough to evaporate the oil. The recovered oil is recovered at the distillation column bottom. The column is then washed and prepared for the next cycle of operation. 
     In an example of the second elution process, freshly distilled hexane is delivered to the top of the column using a distillation system where the eluent bottom of the column is heated at a temperature sufficient to evaporate hexane (68° C.), but not high enough to evaporate the oil. 
     The evaporation temperatures for a particular solvent being employed for elution or cleaning and for a particular pyrolysis oil fraction are (1) between the boiling point of the particular solvent and 32° C. above the boiling point of the most volatile compound in the particular pyrolysis oil fraction or (2) preferably, between the boiling point of the particular solvent and 10° C. above the boiling point of the most volatile compound in the oil fraction or (3) most preferably, between the boiling point of the particular solvent and 2° C. above the boiling point of the most volatile compound in the oil fraction. 
     For example, for hexane being used to clarify unfractionated pyrolysis oil, the ranges would be (1) between about 68° C. to 100° C. or (2) preferably between about 68° C. and 78° C. or (3) most preferably, between about 68° C. and 70° C. The ranges for the other alkanes will be known to those skilled in the art and can be readily determined. 
     While the preferred alkanes are ones having 4 to 10 carbons, it will be appreciated that they may be employed individually, in the process, hexane and butane, for example, may be employed in combinations. Also, while for purposes of example, hexane, the preferred alkane has been used individually, other alkanes within the preferred group having 4 to 10 carbons may be employed individually. 
     In this manner, solvent is delivered to the top of the column continuously. The flow is controlled through the column at approximately 4 liters per hour, washing the bed with up to 30 bed volumes using valve at the bottom of the column. 
     The difference between this process and a known standard column chromatography process is our distillation-elution method employed less solvent and higher temperature. The present invention differs from soxhlet which is used to continuously soak a solid, in our case clay, to remove bound or captured material. It does not flow the solvent through the material in a top down fashion as is required for chromatography, thus, it is not appropriate for our process. In another process, fiber thimbles permit the residue to flow out to the sides of the crucible. This brings a portion of the extract to the bottom of the vessel without residence time with clay thereby minimizing contact therebetween. 
     Our process has been found to be more effective for removal of the polar substances from the oil and polar substances from the column during cleanup. 
     An example of a cycle of operation of the system of  FIG. 1  will be considered. The system shown in  FIG. 1  employs evaporation and gravity in order to deliver solutions and uses about 10 to 15 times less solvent than the forced-flow elution method shown in  FIG. 2  to be described hereinafter. In order to achieve the same degree of purification in this example of the distillation-elution method, the oil and hexane are mixed at an oil to hexane ratio of about 1.4 to 1.15 and most preferably about 1:6 to 1:10 ratio of oil to hexane prior to charging onto the column. The oil and hexane are mixed in vessel  13  and is allowed to sit for about two or more hours. Solids that precipitate in vessel  13  may be removed by filtration or centrifugation or can be left suspended in this fluid. The liquid is fed by gravity through valve  24  to column  17  at approximately the rate of 0.22 liters per hour of column flow per liter of void volume. The bottom valve  26  remains closed for about 1 to 2 hours contact time. Valve  26  is opened and a volume of hexane equivalent to the oil and hexane mix in tank  20  is maintained at a boiling temperature by heat exchanger  14  which is at least 68° C. for hexane. The hexane vapors travel through tube  16  and are condensed by condenser  10 . The condensed hexane drips through valve  24  and on to and through column  17  and then from valve  26  into tank  20 . The flow is preferably controlled at about 0.1 to 0.6 liters per hour of column flow per liter of void volume using valve  26 . The oil elution process is complete after about 10 to 30 column bed volumes of hexane have been eluted through column  17 . 
     At this point valve  23  is opened and valve  24  and  26  are closed. The contents of tank  20  are heated to at least 68° C. to remove the hexane completely by evaporation from tank  20 . In the case of hexane, it is evaporated from tank  20 , passes through tube  16  through open valve  23  and is condensed by condensers  10  and  12  for delivery to tank  18 . Product oil in tank  20  is then drained through valve  25  into tank  21 . After that, valve  25  is closed and tank  21  is replaced with a clean tank. The residual hexane is removed from the clay by closing valves  24  and  26  to isolate the column  17  and heating the column using heat exchanger  15  to evaporate residual hexane through condenser  11  and into tank  18 . 
     The column is then cleaned with a polar solvent. The preferred solvent for cleaning the clay is acetone. In the case of acetone, it is transferred into tank  20  while valves  23 ,  25  and  26  are in the closed position. Valve  24  is open to the condenser  10 . Tank  20  is heated to the boiling point of acetone using exchanger  14 . The acetone from tank  20  evaporates and passes through tube  16 , after which it is condensed in condenser  10  and drips through valve  24  and onto and through column  17 . The bottom valve  26  is open to allow dripping into tank  20 . This is continued for about 30 bed volumes (the volume of clay in the column is a “bed volume”). Tanks  18  and  21  are replaced with clean tanks for this part of the process. Valves  24  and  26  are closed and valve  23  is open. Tank  20  continues to be heated until the acetone is completely evaporated. The acetone vapors travel through tube  16  and are condensed through condensers  10  and  12 . Recovered acetone is collected in tank  18 . The waste material collected in tank  20  is drained through valve  25  into tank  21  for disposal or alternate use. The tanks are then cleaned and are ready for their initial set up for the processing of the next batch. 
       FIG. 2  illustrates schematically an example of a forced-elution apparatus usable in the method of the present invention. In this example, a ratio of oil to hexane of 1:6 to 1:10 is employed. The oil-hexane mixture is in vessel  40  and is allowed to sit for about two hours. Solids that precipitate in the vessel  40  may be removed by either filtration or centrifugation or can be left suspended in this fluid. The liquid is pumped through valve  33  by pump  31  and onto column  22 . The oil is pumped slowly onto the top of the bed and fluid is collected from the bottom of the column  22  at approximately 0.22 liters per hour of column flow per liter of void volume (using a column with approximately an 18.2 liters void volume which is equivalent to 4 liter per hour column flow). Once the material is charged onto the column  22 , the column bottom valve  36  is closed for about 1 to 2 hours to allow sufficient contact time between the liquid and the clay. Valve  36  is then opened and valve  33  is turned open to allow hexane from tank  41  to be pumped by means of pump  31  onto the column  22  at a rate of approximately 0.22 liters per hour of column flow per liter of void volume (using a column with approximately an 18.2 liter void volume which is equivalent to 4 liters per hour column flow.) The column is then washed with about 30 times the volume of oil-hexane that was charged into the column of hexane from tank  41  with valve  36  open,  37  closed and valve  35  in the open position and into tank  27 . Tank  27  is heated to approximately 68° C. by heating jacket  28  and vapors condensed by condenser  44 . Hexane is collected in tank  45  until only oil remains in tank  27 . The cleaned oil is then delivered though valve  37  into tank  29 . Valves  33 ,  35 ,  36 ,  37  are closed with valve  32  being open. Jacket  42  is heated and jacket  43  is cooled to allow the residual hexane to be removed from the column  22  and the clay to be dried. Tank  45  will hold all recovered hexane which ultimately will be pumped through valve  38  by pump  30  to tank  41  for reuse. 
     The evaporation temperatures for a particular solvent being employed for elution or cleaning and for a particular pyrolysis oil fraction is (1) between the boiling point of the particular solvent and 32° C. above the boiling point of the most volatile compound in the particular pyrolysis oil fraction or (2) preferably, between the boiling point of the particular solvent and 10° C. above the boiling point of the most volatile compound in the oil fraction or (3) most preferably, between the boiling point of the particular solvent and 2° C. above the boiling point of the most volatile compound in the oil fraction. 
     For example, for hexane being used to clarify unfractionated pyrolysis oil, the ranges would be (1) between 68° C. to 100° C. or (2) preferably between 68° C. and 78° C. or (3) most preferably, between 68° C. and 70° C. 
     A column bed that could treat four liters of oil employed in an example test was approximately 18 inches in diameter and 24 inches high and have a capacity of approximately 34 liters. The bed was filled with about 16 Kg of clay which is approximately 32 liters and was wet with approximately 20 liters of hexane. The column distribution consisted of screen plates and glass wool at the top and at the bottom with a valve at the bottom to control flow. 
     As shown in  FIG. 2 , valve  38  is opened and the contents of tank  45  is pumped through pump  30  into tank  41 . When the transfer is complete, valve  38  is closed. Tank  41  is replaced with a tank containing acetone. Acetone from tank  41  is pumped though valve  33  using pump  31  and is delivered into column  22 . The acetone extracts the material in column  22  and delivers it through open valve  36  into tank  27 . 
     The material collected in tank  27  is evaporated to collect acetone into tank  45 . Vapors passing through open valve  35  are condensed by cooling jacket  44  with the acetone being collected until only waste residue remains in tank  27 . The temperature ranges for the wash procedure are as described hereinbefore. Waste material from tank  27  is drained through valve  37  to tank  29  for disposal or alternate use. The tanks are then replenished to the initial setup conditions for the next cycle of operation. 
     The following discloses two alternate embodiments with respect to the foregoing disclosure which focus on separation of vaporized nonpolar solvents and separating them from the pyrolysis oil using in one instance a wiped film evaporator and, in another, distillation column. Apart from the specific way disclosed method and apparatus variations focusing on these alternate embodiments the preferred characteristics may remain the same as the foregoing. 
     The additional embodiments disclosed in this continuation-in-part application involve the use of a wiped film evaporator (WFE) or a distillation column. The solvent is stripped from the oil exiting the clay column using a distillation column or a wiped-film evaporator (WFE). This involves heating the mixture of oil and solvent in a tank at a temperature above the solvent&#39;s boiling point and below the boiling point of the oil. 
     The variations in the system for clarification of pyrolysis oil shown in  FIGS. 3 and 4  employ evaporation and gravity in order to deliver solutions to the column as does the original invention. Identical reference numbers will be employed for the same elements in both  FIGS. 3 and 4 . These embodiments also use about 10 to 15 times less solvent than the forced-flow elution method shown in  FIG. 2  of the original application. In addition, these embodiments allow for continuous operation, limited to the capacity of the absorbent packing column  69 . In order to achieve the same degree of purification in this example of the distillation-elution method, the oil and alkane, which is preferably hexane, are mixed at a ratio of oil to alkane of about 1:4 to 1:15, and preferably a 1:6 to 1:10 ratio of oil to hexane prior to charging onto the absorbent column  69 . The oil and hexane are mixed in vessel  63  and the mixture is allowed to sit for at least about two hours. Solids that precipitate in vessel  63  may be removed by filtration or centrifugation or can be left suspended in this fluid. The liquid is fed by gravity through valve  74  to absorbent packing column  69  at approximately the rate of about 0.1 to 0.6 liters per hour of column flow per liter of void volume and preferably, at a rate of about 0.2 to 0.3 liters per hour of column flow per liter void volume. The bottom valve  76  remains closed for about 1 to 2 hours contact time. Heat exchanger  65  may be employed to heat the oil and hexane mixture in absorbent packing column  69  to vaporize the hexane. Valve  76  is opened to a position to allow hexane and eluted oil to flow through pipeline  80  to heated distillation column  67  where the hexane is stripped from the oil and the oil is delivered by gravity through valve  77  to tank  70 . The hexane in vaporized form is stripped from the oil and flows through wiped film evaporator  66  (WFE) or distillation column  67  is condensed by condenser  60  ( FIG. 3 ) or  82  ( FIG. 4 ), respectively and drips through valve  74  on to and through absorbent packed column  69  ( FIG. 3 ). The flow continues through absorbent packed column  69  through valve  76  and back into wiped film evaporator  66  ( FIG. 3 ) or distillation column  67  ( FIG. 4 ). The flow continues through absorbent column  69  and out of the bottom through valve  76  and through pipeline  80  and onto WFE  66  or absorbent packed column  67  where the cycle continues. The flow is preferably controlled at about 0.1 to 0.6 liters per hour of column flow per liter of void volume using valve  76  and temperature control in Wiped Film Evaporator  66  or column  67 . The oil elution process is complete after about 10 to 30 column bed volumes of hexane have been eluted through absorbent packed column  69  or WFE  67  or the absorbent column effluent is clarified. 
     Tank  63  is allowed to empty and absorbent packed column  69  is drained through pipe  80 . Then valve  74  is positioned to stop flow from tank  63  and valve  73  is opened to allow flow through condenser  60  by pipeline  63 ,  77  and into hexane receiving tank  68 . Tank  63  is allowed to empty and absorbent packed column  69  is drained through column  66  to complete the cycle. Recovered vaporized hexane passes by pipeline  78  through condenser  61  and is collected in tank  68 . At this point, the packing in absorbent packed column  69  is regenerated. After the process has been completed, the clay may be regenerated by washing with a polar solvent. 
     Regeneration is preferably accomplished in the following manner. Valve  73  is opened and valves  74  and  76  are closed. Product oil in tank  70  is then drained through valve  75  into tank  71 . After that, valve  75  is closed and tanks  68  and  71  are replaced with clean tanks. Absorbent packed column  69  is then cleaned with a polar solvent. The preferred solvent is acetone. The polar solvent is transferred into tank  63  while valve  74  is in the closed position. Valves  74  and  76  are opened and acetone flows through absorbent packed column  69 , through valve  76 , and into WFE  66  ( FIG. 3 ) or column  67  ( FIG. 4 ). Acetone strips residue oil from absorbent packed column  69  and flows out of the top of column  66  and through absorbent packed column  69  and continues the cycle. The residue from absorbent packed column  69  and WFE  66  transfers by gravity to tank  70 . This is continued for about 20 to 40 bed volumes (the volume of clay in the column is a bed volume) or until column  69  effluent is clear. Valve  74  is positioned to close tank  63  and open pipeline  76 . The acetone is drained from absorbent packed column  69  and cycled through condenser  82  which condenses vaporized hexane which passes through the absorbent packed column  66  through valve  76  and pipeline  80  to Wiped Film Evaporator  66  or column  67  through condenser  60 ,  82 , respectively into tank  68 . Heat exchanger  65  is heated to between about 150° C. and 250° C., valve  74  is closed and residual acetone is driven from the wiped film evaporator  66  or column  67  and flows in pipeline  78  and is condensed through condenser  61  into tank  68  for reuse. The waste material collected in tank  70  is drained through valve  75  into tank  71  for disposal or alternate use. The tanks are then cleaned and are ready for their initial set up for the processing of the next batch. 
     Referring to  FIG. 4 , it will be appreciated that the major components of the system and mode of operation are generally similar to that of the distillation column embodiment of  FIG. 3 . In this embodiment, a column  67  is employed. The mixture of vaporized hexane and oil passes through valve  76  and pipeline  80  to the wiped film evaporator  67 . The portion exiting from the top is condensed in condenser  82  and is either recycled to absorbent packed column  69  or passes through valve  74  to absorbent packed column  69  and then through pipe  78  passes through condenser  61  and is delivered to tank  68 . The lower portion of column  67  has its separated oil delivered through valve  77  to tank  70 . The operation of this embodiment is otherwise similar to the embodiment of  FIG. 3 . The oil in tank  70  can be heated by means of heat exchanger  64  if it is noted that hexane is observed to condense in the tank. 
     We have found that the attapulgite clay works more efficiently after being activated. Activation may be accomplished by drying it at about 120° C. to 300° C. and preferably about 140° C. to 250° C. until there is no weight change. Referring to  FIG. 5 , the appropriate temperature was reached using a TGA with a ramp rate of 10° C./minute to 700° C. Although the clay can be dried above 150° C., clay tends to decompose at that temperature and loses much of its capacity.  FIG. 3  shows the results of Thermogravimetric Analysis (TGA) of the attapulgite testing showing the percent weight loss as a function of temperature. This profile shows the temperature at which free water and hydrated waters evolve. We have found that driving off the higher temperature hydration waters decreases capacity of the clay for the clarification residues. 
     In cleaning the clay for reuse, it is preferred to use a polar solvent such as selected from the group consisting of acetone, methanol, tetrahydrofuran, dimethyl-formamide or another solvent suitable for the purpose. At present, acetone is the preferred polar solvent for this purpose. In cleaning, the flow is controlled through the column at approximately 4 liters per hour washing the bed with up to 30 bed volumes using the valve at the bottom of the column. 
     In another embodiment, freshly distilled hexane is continuously delivered to the top of the column using a distillation system wherein the eluent from the bottom of the column is heated to a temperature sufficient to evaporate the polar solvent, but not high enough to evaporate the oil. For example, for hexane, an effective range might be about 68° C. to 75° C. The ranges for other alkanes known to those skilled in the art can readily be determined. In this manner, fresh solvent is delivered to the top of the column continuously. The flow is controlled through the column at about 2 to 8 liters per hour, with a preferred rate of about 3 to 5 liters per hour washing the bed with up to about 30 bed volumes using a valve at the bottom of the column. 
     Referring generally to  FIG. 6 , it is seen that the hexane feed  200  and pyrolysis oil feed  202  are mixed at  204 . The mixture of the pyrolysis oil and the nonpolar solvent which preferably may be hexane, is delivered to filtration unit  206  resulting in a solubles filtrate  208  and insolubles filter residue  210 . After filtration to remove undesired materials in the filtration unit  206 , the oil/hexane output of filtration unit  206  is directed through solubles  208  clay bed  212 . The output of insolubles  210  will be combined with residual oil  214 . Oil from the clay bed  212 , also known as the absorbent packed column, will become the feed for a distillation unit in  FIG. 7 . 
     Referring now to  FIG. 7 , there is shown a subunit of the global schematic for stripping hexane from the clay bed eluent and separating the hexane from the oil. This is achieved by the distillation unit  302 . Hexane  300  is evaporated and condensed  304  and fed to the top of the clay bed  212  and flows through carrying cleaned oil to the distillation unit  302  to continue the cycle. The heavier clarified oil  306  is separated by gravity and is collected. 
     Referring to  FIG. 8 , which shows another subunit of the global process of  FIG. 6  in which residual hexane  300  is driven off of the clay bed  212  through the condenser  301  and collected for reuse. The clay bed  212  is heated to above the boiling point of hexane but, below the boiling point of the process oil. 
     Referring to  FIG. 9 , the clay bed is cleaned with a polar solvent, preferably acetone  400  to remove the polar residue oil  214 . Acetone  400  strips residue oil  214  from the clay column  212 . The distillation unit  302  strips the acetone  400  from the residue oil  214 /acetone  400  eluted from the clay bed  212 . The residue oil  214  drains down and the acetone  400  evaporates and is condensed and cycled back to the clay bed  212 . This results in the clay bed having been cleaned. 
     Referring to  FIG. 10 , the residual acetone  400  from the clay bed  212  is removed by heating and condensing  304 . This is similar to the process component described in  FIG. 8 . The clay bed  212  is heated to above the boiling point of acetone, but not above the boiling point of the residue oil. 
     While the schematics of  FIGS. 6 through 10  have shown the distillation unit, the alternate embodiment would at the same position, use the wiped film reactor in the manner disclosed herein. 
     Whereas particular embodiments of the invention have been described for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made departing from the invention as defined in the appended claims.