US2749290A - Method and apparatus for continuous percolation of liquid hydrocarbons - Google Patents

Description

J. E. PENICK ET AL METHOD AND APPARATUS FOR CONTINUOUS PERCOLATION OF LIQUID HYDROCARBONS June 5, 1956 Filed July 17,

4 Sheets-Sheet l R W E 1W M w w 0 N .m W W INVENTORS JOE 5. Pam/r BY EHA HTABW/f/A UIL FEfD /N June 5, 1956 Filed July 17, 1951 J. E. PENICK ET AL 2,749,290 METHOD AND APPARATUS FOR CONTINUOUS PERCOLATION OF LIQUID HYDROCARBONS 4 Sheets-Sheet 2 June 5, 1956 J. E. PENICK ET AL METHOD AND APPARATUS FOR CONTINUOUS PERCOLATION OF LIQUID HYDROCARBONS 4 Sheets-Sheet 3 Filed July 17, 1951 TREK/TED 0/1. 007 r INVENTORj- J05 5. PM/M 0/1. FEED //V RA/5741 5mm M a June 5, 1956 J E. PENICK ET AL METHOD AND APPARATUS FOR CONTINUOUS PERCOLATION OF LIQUID HYDROCARBONS 4 Sheets-Sheet 4 Filed July 17 1951 INVENTORS JOE .5. Pm/c/r [/P/VU/AfiW/K/fi United States Patent METHOD AND APPARATU FOR CONTINUOUS PERCOLATION OF LIQUID HYDROCARBONS Joe E. Penick, Woodbury, and Ernest A. Bodkin, Pitman, N. J., assignors to Socony Mobil Oil Company, Inc., a corporation of New York Application July 17, 1951, Serial No. 237,268

22 Claims. (Cl. 196-147) This invention relates to a process for treating liquid hydrocarbons, particularly lubricating oils and lower boiling petroleum fractions which are of low asphalt contentwith solid adsorbents for thepurpose of removing small amounts of impurities or undesirable contaminants therefrom. It is also applicable to processes for Washing and treating adsorbents to recover liquid materials therefrom, to processes for separation of liquid materials by adsorption, and to solvent extraction processes and the like involving contacting of liquid hydrocarbons with a solid adsorbent material.

Typical of the oil treating processes with which this invention is particularly concerned are decolorizatiom neutralization, removal of suspended colloidal or dissolved impurities such as carbon, coke or oxygen and nitrogen-containing impurities and other gum-forming compounds and improvement of demulsibility properties of the oil.

Recently, there has been developed a continuous percolation method which is applicable to processes of the kind above mentioned. In the continuous percolation process an adsorbent of palpable particle form is caused to move downwardly as a columnar mass through a confined treating zone countercurrently to the liquid hydrocarbons beingtreated. A carbonaceous'contaminant is deposited on the adsorbent which reduces its treating efliciency. The spent adsorbent is passed through oil separation, washing, drying and burning steps and then recycled at the proper treating temperature to the treating zone. Oil recovered from the spent adsorbent is; recycled to the treater. This. process is the, subject of claims in United States Patent Number 2,701,786, issued February 8, 19,55. This invention. deals particularly with the operation of the treater portion of the continuous percolation process. The invention is also applicable in, part to some forms of the adsorbent Washing step of the process.

It has been found that exceptionally high treating efficiencies at operating costs far below those encountered by prior art percolation and contacting methods maybe attained by elfecting a true countercurrent contacting between the adsorbent in the form of a column of downwardly moving particles and the liquid hydrocarbons undergoing treatment. In spite of the advantages to be derived from such an operation, its adoption for practical. commercial processing has been heretofore discouraged because of the many technical difficulties involved in the actual physical accomplishment of this method of operation. In treaters of the large diameter and length such as would be required for commercial scale operation, difficulties of adsorbent and liquid flow channeling through localized areas of the treater arise. Also, it is difiicult to maintain continuity of adsorbent flow due to the tendency for adsorbent to bridge and clog the adsorbent feed and drain lines. A further problem arises in efiecting separation of the treated oil from the" adsorbent column and the supply of freshadsorbent to the column surface without encountering substanice ti'al entrainment of fresh adsorbent in the eflluent treated oil product. proper distribution of the oil feed into the adsorbent column and in the withdrawal of the spent adsorbent uniformly from all portions of the column cross-section.

A major object of this invention is the provision of an improved method and apparatus for effecting continuous uniform countercurrent contacting between an upwardly flowing liquid hydrocarbon and acolumnar mass of gravitating adsorbent of palpable particulate form, which method and apparatus overcomes the above mentioned difliculties;

A further object is the provision in a process for countercurrent contacting of a liquid oilwith a downwardly moving column of adsorbent particles of an improved method and apparatus for eifecting uniform and continuous engagement and disengagement of the liquid and absorbent materials.

Another object is the provision in a system for countercurrently contacting a liquid hydrocarbon with a column of downwardly moving adsorbent of palpable particle form of an improved method and apparatus for supplying fresh adsorbent to the column and for removing contacted liquid therefrom Without substantial entrainment of adsorbent particles.

Another object is the provision in a continuous percolation process for decolorizing and purifying lubricating oils of low asphalt content of an eflicient method for continuously effecting uniform countercurrent contact of the oil with a column of downwardly; moving ad sorbent particles.

These and other objects of this invention will become apparent from the following description of the method and apparatus.

In one form of this invention, a column of adsorbent of palpable particle form is maintained along an intermediate portion of a confined treating zone, a body of treated liquid hydrocarbon is maintained above the colum and open to its surface. Also, a body of liquid hydrocarbon feed is maintained below the column and in communication therewith only through restricted passages through which the oil is permitted to How from the body into the column but through which the. ad-

sorbent is prevented from flowing, so that the adsorbent.

Liquid hydrocarbon feed is supplied to the body of liquid feed so as to force the liquid up into and through the.

column at a velocity controlled below the column, disrupting velocity. Treated liquid is withdrawn from the body thereof above the column at a level well above the level of" adsorbent discharge from the confined feed. stream.

In the preferred form of the adsorbent feed and. liquid disengagementand discharge method of this invention, the rateof adsorbent supply to theconiined feed stream is controlled below the maximum possible rate of adsorbent settling in the liquid existing in the lower portion of said stream and the wetted adsorbent particles are discharged from the. confined feed stream at a level under the surface of the treated liquid body and spaced substantially above.

the column surface.

In conducting this method the adsorbent employed should be made up of palpableparticlescf size within the range about 4-100 mesh and preferably about l0 -6O and Further difficulties arise in eiiecting still more preferably 15-30 mesh by Tyler Standard Screen Analysis. The particles may take the form of pellets, capsules, pills, spheres or the like or granules of irregular shape such as are obtained from grinding and screening. The terms adsorbent in palpable particulate form and palpable particle form adsorbents as employed herein in describing and in claiming this invention are intended to generically cover partiles of any or all of these shapesployed but preferably the preparation thereof should be controlled to provide a pore structure similar to that of the clay type adsorbents wherein substantially more than 30 percent of the total pore volume is occupied by macropores. Gels of this type are described in United States Patent 2,188,007, issued January 23, 1940. It should be understood, however, that by proper control of the operation conditions, adsorbents of the synthetic gel type or otherwise having mostly micropores and less than 30 percent macropores may be employed in the process of this invention although with somewhat inferior results when used for lubricating oil purification. On the other hand, gels of this latter type have been found to give superior results in the treatment of distillate fuel oils by the method of this invention. Such adsorbents of this latter type are disclosed in United States Patents 2,3 84,946 and 2,106,744. The invention in its broadest form is intended to be applicable to adsorbents of this type as well as the preferred adsorbents of larger pore structure.

The invention may be most readily understood by reference to the drawings of which Figure l is an elevational view, partially in section, of a preferred form of the invention; Figure 2 is a horizontal cross-sectional view along line 2-2 of Figure 1; Figure 3 is a horizontal cross-sectional view along line 3-3 of Figure 1; Figure 4 is a detailed view of one of the elements of the apparatus of Figure 1; Figure 5 is a horizontal cross-sectional view taken at a level corresponding at 22 of Figure 1 of a modified form of the apparatus of Figure 1; and Figure 6 is an elevational view, partially in section, of a less preferred form of the invention. All of these drawings are highly diagrammatic in form. Figure 7 is an elevational view, partially in section, of a modified form of the upper portion of the apparatus of Figure l, and Figure 8 is a cross-sectional view taken along line 8-8 of Figure 7.

Turning now to Figure 1, there is shown a vertical treater 10 closed on its ends but vented to the atmosphere at its upper end by means of vent 11. The treater may be of any desirable cross-sectional shape, the vessel shown being of circular shape. Above the treater there is provided a single adsorbent feed conduit 12 which extends down from a surge or supply hopper (not shown). The conduit 12 terminates on its lower end on the bottom of the cylindrical receptacle 13 which is of substantially larger diameter than the conduit so as to provide an annular space 14 for receiving adsorbent particles issuing from vertical slots 15 provided along a lower portion of conduit 12. A slidable sleeve 16, operated by cable and crank 17 is provided to permit adjustment of the amount of slot area open for adsorbent escape from conduit 12. A plurality of pipes 18 connect through the bottom of receptacle 13 at spaced points arranged in a ring symmetrical with respect the conduit 12. These pipes extend downwardly through the top of treater 10 and terminates at their lower ends at a level in the upper section of the treater below its upper end and adjacent the open upper ends of vertical tubes 20. The adsorbent flow control and divider arrangement above described is the subject of claims in application Serial Number 237,264, filed in the United States Patent Ofiice on July 17, 1951. One tube 20 is sus pended by means of straps 21 below the lower end of each pipe 18, the tubes being of substantialy larger crosssectional area than the pipes 18. The tubes 20 terminate on their lower ends at .a common level in the upper scction of the vessel 10 which is substantially below the oil collector channel 22 and outlet pipe 23 and substantially above the surface level of the adsorbent column 24. The oil collector channel or trough 22 may be open on its top and is provided with horizontal rows of spaced orifices 25 located at two vertically spaced levels along its opposite sides. The trough 22 is supported by bracket 26 on one end which is closed and by the members forming the collecting basin 27 on its opposite end. The general arrangement of the trough across the treater may be best understood by reference to Figure 2 in conjunction with Figure 1. An oil outlet pipe 23 connects through the vessel wall into the basin 27. The liquid collecting channel and its arrangement in the treater is the subject of claims in application Serial Number 265,832, filed in the United States Patent Oilice on January 10, 1952.

A horizontal partition 30 extends across the lower section of treater 10 above the bottom thereof so as to provide a plenum or liquid distribution space 31. A plurality of uniformly spaced nozzles 33 are distributed uniformly over the entire cross-sectional area of the partition 30 to provide a passage for liquid flow from the plenum space into the portion of the vessel above the partition. A plurality of adsorbent drain conduits 37 fit tightly through the partition at spaced points uniformly distributed across its cross-section and terminate on their open upper ends just above or even with the upper face of partition 30. These conduits extend downwardly through the plenum space 31 and the bottom of the treater. The lateral arrangement of the nozzles and adsorbent drain conduits on the partition 30 is shown in Figure 3. An inlet header conduit 35, closed on its inner end is positioned across the space 31. Oil is supplied into the conduit 35 from pipe 36 which connects through the bottom of the treater and onto one end of the conduit 35. A plurality of oil dirtributor holes 50 are arranged at spaced intervals along either side of the header 35. The adsorbent drain conduits 37 connect in a ring through the top of the funnel shaped collector vessel 38. A single outlet 51 depends from the lower end of vessel 38 and extends down to a motor driven, liquid tight measuring and flow control valve 39. The method and apparatus for withdrawal of adsorbent described hereinabove is disclosed and claimed in detail in application Serial Number 237.267. filed in the United States Patent Office on July 17, 1951.

The construction of the liquid passing nozzles 33 is shown in Figure 4. it will be noted that each nozzle is made up of several parts, one being a body portion 4?) which screws through the partition 30 and has a central passageway for liquid flow. A circular orifice plate 41 rests on a shoulder (not shown) at the top of the body portion 40. A flanged upwardly extending support member (not visible) rests on the orifice and the support member has a passage through its center and openings along its side for escape of liquid laterally from the central passage. A screw 43 screws into the upper end of the central passage of the support member so as to close oi? the same. The head of the screw also serves to hold inplace the screen 42. The support member and orifice plate are held in place by the nut 44. This nozzle is described in detail and claimed in application Serial Number 237,264, filed in the United States Patent Office on July 17, 1951.

For purpose of illustrating the operation of this invention its application to a process for decolorizing lubricating oils will be discussed. It will be noted that there is maintained throughout an intermediate portion of the treater 10 a columnar mass 55 of adsorbent of palpable particle form. As an example, the adsorbent may comprise l30 mesh size (Tyler) granular fuller's earth. A body of treated liquid oil 56 is maintained above the column and open to its surface entirely thereacross. A body of feed liquid 57 is maintained immediately below the column 56 in the plenum space 31 and in liquid flow communication therewith through the restricted passages formed by the nozzles 33. The particles are excluded from the restricted passages and from the liquid body in plenum space 31 by means of the screens 42 on the nozzles 33.

Liquid feed oil is supplied to the body 57 via inlet 36 and distributor 35 so that the liquid is forced up through the restricted passages formed by nozzles 33 into the lower end of column 55. A pressure drop is incurred due to flow through the orifices 41 which are of equal size and uniformly distributed with respect the bed cross section, so as a result the oil enters the bed at a uniform rate over its entire horizontal cross-sectional area. The liquid oil passes upwardly through the bed at a rate controlled at the oil inlet which is below the column disrupting velocity. As a result, uniform countercurrent contacting of the oil and adsorbent is effected and the oil purification and decolorization is accomplished with high eliiciency. The treated oil product passes upwardly from the surface of the column 55 through the body of liquid 56. Thus, very effective settling of any entrained adsorbent is effected and the treated oil leaves the treater via pipe 23 substantially free of entrained particles.

it will be noted that the soaking tubes extend down under the surface of the body of treated oil 56 and the oil rises up into the lower portion of the tubes to seek its normal level. Fresh adsorbent is dropped from pipes 18, at rates controlled by the slot opening 15 so that the particles fall freely through the upper portions of the soaking tubes 20 which are free of liquid and then settle freely through the liquid oil in the lower portion of the tubes. By this procedure the adsorbent is wetted with oil and entrained air or gas is displaced and caused to escape upwardly through the tubes 20 and out through the vent 11. The wetted and degasified adsorbent discharges from the tubes 23 well above the surface of column 55 and settles through the lower portion of the treated liquid body onto the column surface. Spent adsorbent bearing carbonaceous deposits is withdrawn from the bottom of the column downwardly through but out of contact with the body of liquid feed oil and then out from the bottom of the treater via conduits 37. Some liquid oil having properties similar to the feed oil is withdrawn along with the adsorbent particles in the void spaces between the particles. By the arrangement shown substantially equal amounts of adsorbent are withdrawn from all portions of the column cross section so as to insure uniform downward movement of the particles entirely across the column.

The rate of adsorbent throughput is controlled to provide the desired decolorization of the oil being tneated. Once the required adsorbent to oil throughput ratio has been decided upon for a given operation and the oil throughput rate set, the required adsorbent throughput rate can be calculated. T he sleeve 16 is adjusted to permit the required amount of adsorbent to pass to the tubes 29. Once the proper rate is set in this manner, the controller 14 serves only as a fixed constant throttle on the rate of adsorbent introduction. The rate of adsorbent movement through the column 55 and the surface level of the column is thereafter during that operation controlled by means of the valve 39 on the drain conduit 51. The valve 39 which is of the positive displacement type is motor driven and the motor speed and hence the rate of displacement through valve 39 is controlled automatically in response to variations in the column surface level "within the treater. The rate of adsorbent withdrawal is regulated to maintainthe column surface level within a narrow range of levels all more than three and preferably more than six inches below the lower ends of tubes 26. The particular mechanism for automatically measuring the column surface level and adjusting the valve 39 which is shown in Figure 1, involves the measurement of the pressure drop due to oil flow through a vertical section of the treater between taps 47 and 48 arranged at vertically spaced points shortly above and below the desired column surface level. If the column surface level starts to rise, the measured pressure differential increases and this actuates instrument which in turn actuates the motor controller 49 to increase the speed of motor 61, the latter instruments being of conventional type. If the surface level starts to drop, the motor speed and adsorbent flow rates are decreased to compensate. This particular method for controlling the column surface level is the subject of claims in application Serial Number 237,190, filed in the United States Patent Ofiice on July 17, 1951, and now abandoned. If desired, a needle valve or a slide plate with orifices of different sizes may be substituted for the positive displacement valve 39 in the single discharge conduit 51.

it will be noted that in the preferred operation the adsorbent is caused to freely fall through the tubes 20 and a lower portion of liquid body $6 onto the adsorbent column 55. The adsorbent then flows through the adsorbent column and the discharge streams 37 under conditions controlled to maintain the adsorbent in the continuous phase, i. e. the adsorbent particles touch and rest upon each other and the liquid oil fills the void spaces between the adsorbent particles. It is also within the scope of this invention to discharge the adsorbent from the bottom of the column in streams in which the oil is apparently in the continuous phase, or at least under condition wherein the flow is turbulent and follows the how laws of a stream in which the liquid phase rather than the granular adsorbent phase predominates.

While the system disclosed in Figure l constitutes the preferred form of the invention, it is contemplated that within the spirit and scope of the invention the elements thereof may be subject to substantial variation from the particular details of design and arrangement shown in Figure 1. For example, any suitable means known to the art may be employed for supplying fresh adsorbent to the upper ends of tubes 2%) at a controlled or fixed rate. In vessels of relatively small cross-sectional area only one soaking tube 24 may be required. Means other than that shown may be substituted for effecting withdrawal of the liquid oil from the upper portion of the liquid body 56. For example, the outlet device may simply comprise one or more pipes connected to the vessel shell at the proper level.

Also, in the cases of treaters of large diameter it may be desirable to divide the adsorbent column into sectors by vertical partitions and to supply one or more soaking tubes 20 for each sector of the column in the treater. Such an arrangement is shown in Figure 5, in which the vertical partitions are shown at '70 and 71. The partitions 71 may extend the entire length of the column or may extend through only an upper or lower portion thereof.

It is further contemplated that the method for introduction of liquid into the lower section of the column and for maintaining the body of feed liquid below the column may be modified from that shown. For example, simple orifices or nipples of restricted internal diameters may be substituted in partition 30 for nozzles 33 and a screen may be arranged across the vessel above the partition to prevent adsorbent particles from entering the orifices and the body of liquid therebelow. Baffle plates may be provided over the orifices to disperse the flow. Such alternative arrangements are disclosed and claimed in application Serial Number 237,266, filed in the United States Patent Oifice on July 17, 1951. It will be understood that the terms restricted passages and restricted passageways are employed herein in describing and claiming this invention in a broad sense as covering orifices, nozzles, nipples, of small internal diameter and other suit able passageways of restricted cross section adopted to accomplish the function of oil distribution in the manner described.

Further, it is considered that in one form this invention is broad to the particular method for adsorbent supply and treated liquid disengagement from the adsorbent and withdrawal disclosed herein, without regard to the particular method for liquid feed introduction to the column or spent adsorbent withdrawal therefrom. Also considered to be within the scope of this invention is the novel method of treater operation wherein the moving adsorbent column is maintained between two bodies of liquid from which the particles are excluded and wherein fresh adsorbent is supplied to said column by passing downward through at least an upper portion of the liquid body above said column as a confined stream of relatively small cross section and discharging the particles from said stream a substantial distance below the surface of the body of treated oil while treated oil product is withdrawn from the liquid body at a level well above the discharge level of the confined adsorbent feed stream.

An example of a modified form of the invention is shown in Figure 6. In this arrangement, the fresh adsr bent from inlet conduit 12 is measured at a controlled rate by valve 80 into the vertical soaking tube which in this case extends through the top of treater 10. A vent 84 is provided on the tube 20 just below the valve 80. Adsorbent is withdrawn from the bottom of the treater through conduits 85 in which there are provided orifices 86 to control the withdrawal at a fixed rate. The column level is controlled by increasing or decreasing the rate of adsorbent feed in response to fall or rise in the column surface as indicated by float 87 which actuates the motor control instruments 82 and 83. The liquid feed enters from inlet 36 to a laterally extending manifold 88 which in turn feeds the spider arrangement conduits 89. The conduits 89 of which only one may be seen are spaced horizontally apart at equal intervals across the housing cross-section and extend lengthwise nearly entirely across the housing to their closed ends. Orifices 91 are provided at spaced intervals along the conduits 89 so as to provide a uniform orifice area distribution over the entire cross section of the treater. A screen 99 which is of smaller mesh size than the particles of adsorbent but which permits free passage of liquid is wrapped around the conduits to prevent entry of adsorbent into the conduits. Button type baffle 92 plates are welded to the screen over the orifices to break up the high velocity oi] streams issuing from the orifices. Liquid is collected in the upper section of the treater in annular pan or trap formed by the angle type member 93. The valve 80 may be a suitable gate or needle valve and preferably one which provides a symmetrical opening within the feed conduit 20. A suitable adjustable valve for use at this point may be one having an adjustable iris diaphragm such as the valve disclosed in United States Patent 2,458,- 162. It will be noted then in this modification the adjustments on adsorbent flow rate are made during operation on the dry adsorbent stream entering the vessel, while the wet adsorbent stream leaving the vessel is throttled by a fixed orifice. If desired, the adsorbent withdrawal arrangement may be similar to that shown in Figure l with a fixed orifice substituted for the valve 39. Once flow is established at the desired fixed rate through the fixed withdrawal orifice, the flow from the bottom of the column will be steady and uniform and adjustments required to maintain the column level constant may be conveniently and accurately made on the dry adsorbent inlet stream.

A modified arrangement for delivering fresh dry adsorbent to the soaking tubes is shown in Figures 7 and 8 which should be read together. In this arrangement the main adsorbent feed conduit 12 extends into the upper section of the treater. The soaking tube 20 is of annular cross-sectional shape and is supported within the housing by bars 106. Adsorbent issuing from the slots 15 is spread by means of frusto-conical bat'fie which terminates on its lower end over the open upper end of the soaking tube. if desired, the outer wall of the tube 20 may extend upwardly a short distance above the base of battle 105 to prevent escape of any stray particles over the outer rim of the soaking tube. Tubes extend through the annular tube 20 at several points spaced around its upper section at the surface level of the liquid body 56 for by pass of liquid passing up through the space inside the annular tube 20 to the outlet 23.

It will be apparent that within practical limits the operating conditions of the method and the design arrangement and dimensions of the apparatus of this invention may vary widely depending upon the particular process to which the invention is applied and the nature of the liquid hydrocarbon and adsorbent material and the scale of the operation. However, certain general limits have been found to be important and in some cases critical.

As will be apparent from the above, the purpose of the soaking tubes 20 is to permit continuous uninterrupted supply of adsorbent to the column in the treating zone without entrainment in the etlluent liquid hydrocarbon stream. The adsorbent in the dry state contains gas and is relatively light, and in that condition it is readily suspended and entrained in tip-flowing liquid oil streams. By the method of this invention. the liquid oil seeks its level within the lower portion of tubes 20 but in contrast to the remainder of the body 56, the liquid columns within the tubes 20 has no upward velocity component. Thus, the dry adsorbent readily settles into the column of liquid within the tubes and occluded gas is replaced by liquid. It is desirable that the displaced gas should be withdrawn up through the tube 2%) rather than through the body surrounding the tube otherwise turbulence in the liquid body would be promoted. To this end, it is important that the tubes 28 discharge at least 6 inches and preferably 18 to 36 inches below the surface of the liquid body 56. It has been found that if adsorbent is supplied to the tubes at a sulficient rate to provide a compact column thereof in the tubes. there is a tendency for the liquid hydrocarbon to seep up through the column of adsorbent above tle ordinary liquid level in the tube and to cause plugging of the tube by the wetted adsorbent. For this reason, the rate of adsorbent supply to tubes 20 should be restricted so that the adsorbent falls freely through the upper portion of the tubes above the liquid level therein and settles freely through the liquid column in the lower portions of the tubes. Thus, the rate of adsorbent supply to the tubes 20, and the superficial volumetric velocity in the upper portions of the tubes 20 is limited below the maximum settling rates of the dry particles in the liquid in the lower portions of the tubes and in the portion of the liquid body therebelow. Broadly, the rate of adsorbent supply to the upper end of any soaking tube must be below that defined by the equation I 71O,000D- 1M1 ST where U is the rate of adsorbent supply in cubic feet per hour per square foot of soaking tube horizontal crosssectional area (the adsorbent volume here referred to is on the apparent volume basis, that is, the volume of an equal amount of the dry adsorbent when fiowing as a substantially compact throttled stream or as poured into a graduate without agitation of the graduate), Z is the viscosity in centipoises of the liquid hydrocarbon under the condition in the treater and specifically within the ar' raaee lower portion of the tube 20 and is below about 560 centipoises, D is the average adsorbent particle diameter in inches (calculated by averaging the reciprocal of the particle diameters), and above about 0.01 inch, 8a is the dry adsorbent apparent density in grams per cubic centimeter (conveniently determined by pouring a sample of the adsorbent into a graduate without ag tauon and Weighing a measured amount), F is the fraction of voids between the adsorbent particles in grams per cubic centimeter under the same mass conditions at which Sa is determined and generally within the range about 0.30 to 0.55, St. is the density in grams per cubic centimeter of the liquid hydrocarbon under the conditions in the treater and specifically within the lower portion of tube 20 and ST is the true density of the dry adsorbent in grams per cubic centimeter. Preferably the rate of ad sorbent supply to each soaking tube should be approximately that defined by the equation 11 U 443,00OD2 Sa s L) Z 1-1 ST Since the upper portions of the tube 20 are not filled with a compact mass of adsorbent, ample flow area is provided in the tube for escape of gas displaced from the adsorbent. However, it has been found desirable to limit the vertical distance from the liquid body surface to the upper end of the tube or to a vent on the tube below about 3 feet and preferably below about 1 /2 feet.

The wetted particles settle from the lower end of each tube 20 through the intervening portion of the liquid body 56 onto the surface of the column 55. There is a tendency for the adsorbent to form a mound on the column surface directly below each tube 20 particularly when the end of the tube is near the column surface. In order to prevent such mounds from acting as throttles, on the discharge of adsorbent from the lower ends of tubes, which would result in turn in eventual stoppage of flow due to plugging of the tubes by wetted and compacted adsorbent, it is preferred to maintain the lower ends of tubes 20 at a level more than three inches and preferably more than six inches above the general surface level of the adsorbent column. For best operation, the lower ends of the tubes should be l8-36 inches above the surface of the adsorbent column. Also, the lower ends of the tubes 20 should be more than three and preferably more than six inches and for best operation 18-36 inches below the surface of the body of liquid oil 56. In order to maintain minimum liquid velocities in the body 56 it is desirable that Within the limits above discussed the tubes 20 occupy as little of the housing cross section as possible. The lateral dimensions of each tube amounts to only a small fraction of the corresponding lateral dimensions of the treater but each tube should have lateral dimensions in any direction greater than 3 and preferably greater than 6 inches. In any case, the total of the cross-sectional areas of all the soaking tubes amounts to only a minor fraction of that of the liquid oil body 56, usually less than about 5 percent.

Small amounts of adsorbent entrainment in the efiluent oil product may occur when the oil velocity is relatively high. It has been found highly desirable to limit this entrainment in any case below about 0.6 pound of adsorbent per barrel (42 gallons) of liquid product. This may be when the following relationship is maintained:

where H is the vertical distance in feet between the column surface and the surface of liquid body 56, and within the the range 6 inches to 8 feet; R is the superficial oil rate through the liquid body 56 in 42 gallon barrels per day per square foot of liquid body horizontal cross-sectional area; Z is the liquid oil viscosity under the conditions in .10 the liquid body 56 and within the range 02-500 centipoises; D is the average adsorbent particle diameter in inches and within the range 0.0058-0185 inch; Sa, SL, ST and F are as defined hereinabove in connection with Equations LIV.

The operating conditions Within the treater may involve temperatures within the range atmospheric to 700 F. and pressures near or moderately below or in excess of atmospheric pressure. The relative amounts of adsorbent and liquid oil feed passed through the treater depend upon the degree of decolorization or other treatment desired. In general, the volumetric ratio of liquid oil measured at 60 F. to adsorbent (packed density) falls within the range 0.3 to 30.

The superficial velocity of liquid oil through the treater should be within the range /;:-20 feet per hour and preferably Within the range 1-10 feet per hour. (Based on oil at treating temperature and free cross-sectional area of treater when empty.) In all cases, the oil velocity should be controlled below that which would interfere with the downward direction of flow of the adsorbent particles. While some expansion in the columnar mass due to oil flow may be tolerated, oil velocities should be avoided which are so high as to cause the adsorbent particles to move upwardly through the treating zone since such high velocities would prevent true countercurrent contacting of the oil and adsorbent with resultant decrease in the efficiency of the treating process.

In general, the adsorbent particles touch each other as they move downwardly within the column so that it may be said that in this portion of the treating zone the adsorbent is the continuous phase whereas in the portion of the treater occupied by the body of treated oil above the surface of the column, the liquid oil is the continuous phase. In order to properly maintain the columnar mass in the condition above discussed, the superficial velocity of the liquid hydrocarbon in the portion of the treater occupied by the adsorbent column should be maintained below the maximum defined by the equation,

where V is the superficial velocity of the oil in feet per hour (calculated on the basis of the total zone cross sectional area when empty of adsorbent) and the remaining variables are as defined in connection with Equation 1. Preferably, the superficial velocity should be below that defined by the equation,

Broadly, the oil viscosity should be below 500 centipoises and usually a viscosity in the range of about 5 centipoises is preferred.

The vertical length of the adsorbent column in the treating zone should be greater than about 5 feet and preferably from l050 feet. If desired, the invention may be applied to the adsorbent washing step of the continuous percolation process wherein occluded oil is washed from a down-flowing column of adsorbent by means of an upwardly percolating solvent such as petroleum naphtha, carbon tetrachloride, carbon disulfide or normal heptane. In general, the same limits discussed hereinabove apply to the washing step except that the operating temperature may be somewhat lower.

In the liquid introduction step, it is desirable to so restrict the cross section of the passageways communicating the body of feed liquid with the column of adsorbent thereabove that the pressure drop due to flow through the orifices at the desired total throughput rate amounts at least to the sum of four times the flow head in the plenum space plus one-fourth of the pressure drop due to flow through the column exclusive of the hydrostatic head, or pressure drop due to flow across the plenum chamber to the restricted passageway plus one-fourth of the pressure drop due to oil flow through the vertical length of adsorbent column above the restricted passageway exclusive of hydrostatic head. When the pressure drop across the plenum chamber below the restricted passageways is very small or when the liquid is presented to all of the restricted passageways at the same pressure, the pressure drop through the passageways at the required flow rate should be at least one-fourth of and preferably equal to the pressure drop due to oil flow through the column of adsorbent. The restricted passages thus required have a total cross section amounting usually to less than one percent of the treater cross section. In general, for proper distribution of the oil into the column, the minimum number of spaced restricted liquid flow passages is defined by the equation,

where A is the horizontal cross-sectional area in square feet of the adsorbent column and L is its vertical length in feet above the restricted oil inlet passages.

While the invention is not limited in its broader aspects to any particular method of adsorbent withdrawal from the treater, it has been found that by far the best operation can be obtained by method discussed in connection with Figure l. Generally, at least one adsorbent withdrawal pipe should be provided for each 12 square feet of column cross section in order to insure uniform withdrawal of adsorbent all across the column. In any case, less than l7 square feet of column area should be allotted to each withdrawal conduit. Further, the minimum diameter of the withdrawal conduits should be at least 20 times the diameter of the particles, otherwise frequent stoppage of the flow will be encountered. The preferred method for adsorbent withdrawal shown in Figure 1 is disclosed in detail and claimed in application Serial Number 237,267, filed in the United States Patent Ofiice on July 17, 1951.

Some liquid oil is withdrawn from the column along with the adsorbent. It has been found that for high, turbulcnt stream velocities in the withdrawal conduits the liquid forms the continuous phase or the flow follows the principles which are to be expected from such condition. On the other hand, solid material forms the continuous phase when the stream velocities are low and non-turbulent. The fiow capacity of a given conduit is very considerably higher when the oil is the continuous phase in the withdrawal stream than when the adsorbent is the continuous phase. Due to the very wide difierence in flow capacities of a given discharge conduit or orifice under these two conditions it is substantially impossible to accurately control the rate of adsorbent withdrawal in the border line region unless liquid tight positive displacement valves are employed in the discharge conduit 51. When orifices or needle valves are employed to reg..- late the rate of adsorbent withdrawal, it is important to adjust the withdrawal stream velocity well below or well above the velocity corresponding to the border line velocity at which the continuous phase changes from solid to liquid. in any case, it is preferred to restrict the rate of wet adsorbent flow in each of the pipes 37 below 350 cubic feet per hour per square foot of pipe cross section in order to insure proportional flow through all the pipes into the collector 38 and single centrally located discharge conduit 51. This is on the basis of the wet adsorbent and exclusive of any free liquid which may be removed in the discharge stream in the space between adsorbent particles.

As an example of this invention, an apparatus was constructed in the manner disclosed in Figure l. The treater measured 8 feet in diameter and the column height above partition 30 was about 17 feet. The depth of the feed liquid body below the column was about 1.2 feet and of the treated liquid body above the column about 3 feet. The adsorbent was supplied through six soaking tubes 1% feet in length and 9 inches in internal diameter.

The feed pipes 18 were one inch standard pipe size. The channel 22 was omitted and the oil outlet pipe 23 was located 6 inches below the top of the tubes 20. The adsorbent column surface was maintained about 18 inches below the lower ends of tubes 20.

In the partition 30 there were provided 115 nozzles 33 on 3 inch centers with .086 inch orifices therein. Adsorbent was withdrawn through 29 two inch standard pipe size conduits.

in a typical operation a blend consisting of equal volumes of intermediate naphtha and a duo-sol treated bright-stock lubricating oil from 21 Mid-Continent base crude, having an initial color of 100 Lovibond was supplied to the treater via pipe 36 at a rate of 640 barrels per day. The superficial oil velocity in the column was about 3.0 feet per hour. The treating temperature was about 77 F., the pressure about atmospheric and the oil viscosity under treater conditions about 5.2 centipoises. Treated oil withdrawn at pipe 23 was substantially free of adsorbent and had a color of 44 Lovibond. The adsorbent employed was 15-30 mesh size (Tyler) fullers earth which was passed through the treater at a rate of 550 pounds per hour which was about 0.072 pound of adsorbent per pound of treated oil product. About 3.3 barrels of oil per hour were withdrawn from the treater with the spent adsorbent. This oil was separated from the adsorbent and recycled to the treater. The adsorbent was washed, dried and regenerated and returned at its original activity to the treater for reuse therein.

It is intended to cover all changes and modifications of the examples of the apparatus and of the operation of this invention herein chosen for purposes of disclosure which do not constitute departures from the spirit and scope of the invention.

We claim:

1. A method for countercurrently contacting a liquid hydrocarbon feed which remains in the liquid phase during the contacting with a downwardly moving column of adsorbent which comprises, maintaining a column of adsorbent of palpable particle form along an intermediate portion of a confined, elongated contacting zone, maintaining a body of liquid hydrocarbon feed in a lower portion of said treating zone immediately below said column of adsorbent and in liquid fiow communication with the bottom of said column, substantially excluding the particles of adsorbent from said body of liquid, maintaining a body of contacted liquid in an upper portion of said treating zone immediately above and open to the surface of said column, withdrawing used adsorbent from the lower section of said column while maintaining said body of feed liquid free of said particles, replenishing said column at its upper end with feed adsorbent while substantially excluding the feed adsorbent from at least the upper portion of said body of contacted liquid hydrocarbon, introducing liquid hydrocarbon feed into the body of feed liquid so as to force the liquid to flow upwardly into and through said column of adsorbent, and withdrawing contacted liquid from the upper portion of said body of contacted liquid hydrocarbon.

2. A method for treating a liquid hydrocarbon feed which remains in the liquid phase during the treating by countercurrent contact with a downwardly moving column of adsorbent which comprises, maintaining a column of adsorbent of palpable particle form along an intermediate portion of a confined, elongated treating zone, maintaining a body of liquid hydrocarbon feed in a lower portion of said treating zone immediately below said column of absorbent and in liquid flow communication with the bottom of said column, substantially excluding the particles of adsorbent from said body of liquid, maintaining a body of treated liquid in an upper portion of said treating zone immediately above and open to the surface of said column, withdrawing used adsorbent from the lower section of said treating zone by passing a m-gage the adsorbent downwardly along with some liquid hydrocarbon as a plurality of confined horizontally spaced streams through said body of iiquid feed but out of contact therewith and then out from the lower section of said treating zone, supplying fresh adsorbent to the upper end of said column by passing it downwardly through at least an upper portion of said body of treated liquid as a plurality of horizontally spaced confined feed streams from which the adsorbent particles discharge a substantial distance below the surface of said body of treated liquid, supplying liquid hydrocarbon feed to said body of feed liquid so as to force the liquid to fiow upwardly into said column of adsorbent, passing the liquid upwardly through said column at a velocity controlled below the column disrupting velocity, whereby the liquid is treated by countercurrent contact with said adsorbent and withdrawing treated liquid from said body of treated liquid hydrocarbon at a level above that at which said fresh adsorbent discharges from said confined feed streams.

3. A method for treating oils of low asphalt content to purify the same which comprises, introducing an adsorbent of palpable particulate form into the upper section of a confined treating zone in a plurality of horizontally spaced confined feed streams discharging a substantial distance below the surface of a body of the treated oil maintained in the upper section of said zone, at a plurality of points uniformly distributed across the horizontal cross-sectional area of said treating zone, causing the adsorbent particles to fall freely through a vertical section of said body of oil onto a column of said adsorbent and passing the adsorbent in said column downwardly within said treating zone countercurrently tothe liquid oil undergoing treatment, while controlling the velocity of oil flow below the column disrupting velocity, withdrawing spent adsorbent from a plurality of points uniformly distributed across the bottom of said column as a plurality of confined streams which extend downwardly through a lower portion of said treating zone in which there is maintained a body of liquid feed oil, while excluding entry of free adsorbent particles from the bottom of said column into said body of feed oil, supplying feed oil to said last named body to force oil to flow upwardly into and through said column and then upwardly in said body of treated oil and withdrawing decolorized oil product from said body of treated oil above the level of discharge of said confined adsorbent feed streams.

4-. A method for treating oils of low asphalt content to purify the same which comprises, maintaining a column of adsorbent of palpable particle form along an intermediate portion of a confined treating zone; maintaining a body of treated liquid oil above said column and open to the column surface and maintaining an adsorbent free body of liquid oil feed below said column and in liquid flow communication with the column above through a plurality of restricted passages from which the adscrbent particles are substantially excluded, said passages being uniformly distributed over the horizontal crosssectional area of said treating zone; passing fresh adsorbent downwardly through an upper portion of said body of treated oil from which adsorbent is otherwise substantially excluded as a plurality of spaced confined streams of freely falling particles, the adsorbent contacting liquid oil within said confined streams, whereby gas is removed from the adsorbent; discharging said streams into a lower portion of said body of treated oil at a plurality of points spaced substantially above the column surface and uniformly distributed over the horizontal cross-sectional area of said treating zone; permitting the adsorbent particles from said streams to descend freely through the oil onto the surface of said column; withdrawing spent adsorbent from a plurality of points uniformly distributed across the bottom of said column as a plurality of confined streams of small cross section relative to that of said column; leading said strearns downwardly through said body of feed oil and then out from the lower section of said treating zone; supplying the feed oil to said body thereof to force the oil to flow upwardly through said restricted passages into and then through said column and controliing the velocity of oil fiow in said column below that which would disrupt said column, whereby the oil is treated by countercurrent contact with said adsorbent; and withdrawing treated oil from the upper portion of said body of treated oil above the level of discharge of said confined adsorbent streams therein. I

5. In a process wherein liquid hydrocarbons are passed upwardly through a column of downwardly moving adsorbent of palpable particle form maintained in a confined contacting zone, the method for continuously supplyingadsorbent to said column without entrainment in the efiiuent contacted hydrocarbons which comprises, maintaining a body of contacted liquid hydrocarbons above said column and passing the contacted hydrocarbons upwardly from the surface of said column as said body to efiect settling of any entrained adsorbent particles and withdrawing the contacted liquid hydrocarbons from the upper portion of said body, passing feed adsorbent downwardly through an upper portion of said body as at least one confined stream of freely falling particles, said stream being restricted in cross section to only a minor fraction of that of said body and the adsorbent in the lower portion of said stream being brought into contact with liquid hydrocarbons isolated in said stream from the main portion of said body, whereby the adsorbent particles are degasified and wet in said stream, discharging said adsorbent downwardly from said stream into the lower portion of said body of liquid at a location substantially below the surface of said body and above the surface of said column and permitting the adsorbent to descend freely through the lower portion of said body of contacted liquid onto the surface of said column.

6. A method for treating oils of low asphalt content to purify the same which comprises, maintaining a column of adsorbent of palpable particle form along an intermediate portion of a confined treating zone, maintaining a body of treated liquid oil above said column and open to the column surface, passing fresh adsorbent downwardly through an upper portion of said body of treated oil from which adsorbent is otherwise substantially excluded as a plurality of spaced confined streams of freely falling particles, the adsorbent contacting liquid oil withing said confined streams, whereby gas is removed from the adsorbent, discharging said streams into a lower portion of said body of treated oil at a plurality of points spaced substantially above the column surface and uniformly distributed over the horizontal cross-sectional area of said treating zone, permitting the adsorbent particles from said stream to descend freely through the oil onto the surface of said column, withdrawing spent adsorbent from the lower section of said column so as to promote downward movement of the adsorbent particles in said column, introducing the liquid oil feed into the lower section of said column and passing it upwardly therethrough at a superficial velocity controlled below that which would disrupt said column, whereby said oil is purified by true countercurrent contact with said adsorbent and withdrawing treated oil from said body of treated oil at a level in said treating zone substantially above the level of discharge of said confined streams of fresh adsorbent thereinto.

7. In a process wherein a liquid hydrocarbon material is passed upwardly through a column of downwardly moving adsorbent of palpable particle form in a confined contacting zone and the contacted liquid is withdrawn from the upper section of said zone, the method for supplying adsorbent to said column and withdrawing contacted liquid from said contacting zone without substantial entrainment of the adsorbent particles which comprises: maintaining a column of contacted liquid hydrocarbon material above the surface of said adsorbent column in said contacting zone; passing the dry adsorbent downwardly through a confined passage discharging it at a location more than six inches below the surface of said body of liquid and more than six inches above the surface of said column, said passage i being limited in cross-sectional area to only a minor fraction of that of said body of liquid and being open on its lower end to said body whereby the liquid rises into said passage to wet the particles of adsorbent falling therethrough; causing the adsorbent to drop from the lower end of said passage and to settle freely through the intervening portion of the body of contacted liquid on to the surface of said column; controlling the superficial velocity of the adsorbent in said passage below the maximum settling velocity of the adsorbent in the liquid in and below said passage by limiting the rate of. adsorbent supply to said passage below that expressed by the equation Sa S1, 2 1-F si) where U is the rate of adsorbent supply to said passage in cubic feet per hour per square foot of passage crosssectional area, Z is the viscosity in centipoises of the liquid hydrocarbon under the conditions in said passage, D is the average particle diameter in inches of the adsorbent, S is the apparent density in grams per cubic centimeter of the dry adsorbent, ST is the true density in grams per cubic centimeter of the dry adsorbent, Sr. is the density in grams per cubic centimeter of the contacted liquid under the conditions in said passage, and F is the fraction of voids in the dry adsorbent when massed to give the apparent density Sa; flowing contacted oil upwardly within said contacting zone from the surface of said column as said body of liquid whereby any entrained particles are settled and withdrawing the contacted liquid from the upper section of said body above the location of adsorbent discharge from said confined passage.

8. A method for treating oils of low asphalt content to purify the same which comprises: maintaining a column of adsorbent of palpable particle form along an intermediate portion of a confined treating zone; maintaining a body of treated liquid oil above said column and across its entire surface; passing fresh adsorbent downwardly from a location above said body of treated oil through an upper portion of said body from which adsorbent is otherwise excluded as a plurality of spaced confined streams of adsorbent particles which fall freely through an upper portion of said streams and settle freely through liquid oil within a lower portion thereof, said streams having a total horizontal cross-sectional area amounting to only a minor fraction of that of said body of liquid; discharging the particles from the lower ends of said streams into the open body of treated oil at a evel more than six inches below its surface and more than six inches above the surface of said column of adsorbent and permitting the particles to settle freely down through the intervening portion of said body of liquid onto said column; continuously supplying fresh adsorbent to said confined streams at a rate below the maximum settling velocity of the adsorbent through the liquid oil in the lower portion of said streams by limiting the rate of adsorbent supply to each of said confined streams below that expressed by the equation where U is the rate of adsorbent supply to said stream in cubic feet per hour per square foot of stream. crosssectional area, Z is the viscosity in centipoises of the treated oil under the conditions in said stream, D is the average adsorbent particle diameter in inches, Sa

is the apparent density and ST the true density in grams per cubic centimeter of the dry adsorbent, Sr, is the density in grams per cubic centimeter of the oil under the conditions in said stream and F is the fraction of voids between adsorbent particles under the same conditions as Sa; withdrawing spent adsorbent from the lower section of said column so as to promote downward movement of the adsorbent particles in said column; introducing the liquid oil feed into the lower section of said column and passing it upwardly therethrough at a superficial velocity controlled below that which would disrupt said column, whereby said oil is purified by true countercurrent contact with said adsorbent; flowing treated oil upwardly within said treating zone from the surface of said column as said body of liquid, whereby any entrained particles are settled and withdrawing the purified oil product from the upper portion of said body above the location of fresh adsorbent discharge from said confined streams.

9. A method for treating oils of low asphalt content to purify the same which comprises, maintaining a column of adsorbent of palpable particle form along an intermediate portion of a confined treating zone; maintaining a body of treated liquid oil above said column and open to the column and across its entire surface; passing fresh adsorbent downwardly through at least one vertical confined passage from a level above said body of oil to a discharge level more than six inches below the sur' face of said body of treated oil and more than six inches above the surface of said column, said passage having maximum lateral dimensions amounting to only a small fraction of the corresponding lateral dimensions of said liquid body and minimum lateral dimensions greater than about 3 inches, and said passage being open on its lower end so that liquid oil rises into the lower portion thereof to seek its level and thereby to wet the particles of adsorbent dropping through said passage; causing free fall of the particles through the upper portion of said passage not occupied by liquid by supplying adsorbent to said passage at a rate below that defined by the equation r si) where U is the rate of adsorbent supply to each passage in cubic feet per hour per square foot of passage cross section, Z is the viscosity in centipoises of the oil in the treating zone and is below about 560 centipoises, D is the average adsorbent particle diameter in inches and is above about 0.01 inch, Sa and ST are the apparent and true densities respectively in grams per cubic centimeter of the dry adsorbent, Sr, is the density in grams per cubic centimeter of the oil in the treating zone under the conditions therein and F is the fraction of voids between the adsorbent under the same mass conditions as Sn and within the range 0.30 to 0.55; permitting the ad sorbent particles to settle from the lower end of said passage through the intervening lower portion of said body of treated oil onto the surface of said column; withdrawing spent adsorbent from the lower section of said column so as to promote downward movement of the particles in said column; introducing the liquid oil feed into the lower section of said column and passing it upwardly through said column at a velocity below the column disrupting velocity and the maximum defined by the equation r F T) 250,000D v Z where V is the superficial velocity of the oil through the portion of the treating zone occupied by said column in feet per hour, and D, Z, 812, Sn, Sr, and F are as defined above; flowing treated oil upwardly through the treating zone from the surface of said column as said body of liquid whereby any entrained particles are settled and withdrawing the purified oil product from the upper Sa 1F assume portion of said body above the location of fresh adsorbent discharge from said confined passage.

10. In a process wherein a liquid hydrocarbon. material is. treated by passing it upwardly through a column or downwardly moving adsorbent of palpable particle form in a confined treating zone and the treated liquid is withdrawn from the upper section of said zone, the method for supplying. adsorbent to said column and withdrawing treated liquid from said treating zone without substantial entrainment of the adsorbent particles which comprises, maintaining a body of treated liquid hydrocarbon material above said column: and entirely across its surface, maintaining a continuously supplied single. feed stream of adsorbent above said treating zone, splitting said feed. stream into a plurality of confined secondary streams. and discharging. said secondary streams into a plurality of horizontally spaced vertical passages uniformly distributed over the entire cross-section of. said liquid body and extending downwardly from a level. above the surface of. said liquid body to a level more than 6 inches below the surface thereof and more than six inches above. the surface of said column, each. of said passages being greater than 3 inches in minimum lateral dimension but all of said passages occupying only a small fraction of the horizontal cross-sectional area of said liquid. body, said passages opening on their lower ends to said liquid body so that the liquid seeks its level therein, controlling the rate of adsorbent supply from said single stream to said secondary streams so: that the adsorbent. discharges into the upper end of each ofsaid vertical passages at a rate below that defined by the equation l r" b where U is the rate of adsorbent supply to saidpassages .1 in cubic feet per hour per square foot of. passage crosssectional area, Z' is the. viscosity in centipoises of the treated liquid hydrocarbon under the conditions in said passages; D isthe. average particle diameter ininches of adsorbent, Sa the apparent density in grams per cubic centimeter of the dry adsorbent, ST is the true density in grams. per cubic centimeter of the dry adsorbent, Sn is the. density in grams per cubic centimeter of. the treated liquid under the conditions in said passage, and: F isthe fractionof. voids in the dry adsorbent under the same conditions as Sa, permitting. the adsorbent particles to settle'frorn. the. lower. ends of said passages through the intervening portion of said liquidbody onto'the surface of: said column.- of adsorbent, flowing treated oil upwardly through said treating, zone from the surface of said column as said. body of liquid whereby any entrainedrparticles aresettled: andv withdrawing the treated liquid from the" upper section of. said body above the. locationv of adsorbent discharge from said confined passages.

LI. method for treating. oils: of low asphalt. content .to-purify the same which comprises, maintaining. a column of adsorbentof palpable particle for-m1 along an=intermediate portion of a confined treating zone; maintaining" a body of treated liquid oil above? said column char.ge. level within the. range I8-36 inches below the surface of. said body of. treated oil and within the range 18-36 inches. above the surface of said column, said passagesoccupying only a minor fraction of the horizontal cross-sectional area of said body of liquid but having 7 1 8 minimum lateraldimensions greater than about 3 inches and said passages being open ontheir lower ends so that the liquid oil rises into lower portions thereof to seek its level and to wet the particles of adsorbent falling through the passages; causing free fall of the particles through the upper portion of said passages not occupied by liquid by supplying adsorbent to said passages at a rate approximately equal to that defined by the equation where U is the rate of adsorbent supply to each passage in cubic feet per hour per square foot of passage cross section, Z is the viscosity in centipoises of the oil inthe treating zone and is below about 560 centipoises, D is the average adsorbent particle diameter in inches and is above about 0.01 inch, Sa and Sr are the apparent and true densities respectively in grams per cubic centimeter of the dry adsorbent, Sr. is the density in grams per cubic centimeter of the oil in the treating zone under the conditions therein and F is the fraction of voids between the adsorbent under the same mass conditions as Su and within the range 0130' to 0.55; permitting the adsorbent'particles to settle from the lower ends of said passages through the intervening lower portion of said body of treated oil onto the surface of said column; withdrawing spent adsorbent from a plurality of points uniformly 443,000D Z F distributed across the bottom of said column as a plurality of confined streams of small cross section relative to that of said column; leading said streams downwardly through said body of feed oil and then out from the lower section of said treating. zone; supplyingv the feed oil to said body thereof. to force the oil to flow upwardly through said restricted passages into and then through. said column; controlling the velocity of oil flow in said column below the maximum defined by the equawhere V is the superficial velocity of the oil through the portion of the treating zone occupied by said column in feet per hour, and D, Z, Sa, Sn, ST and F are as defined above; flowing treated oil upwardly through said treating zone from the surface of said column as said body of liquid whereby any entrained particles are settled and withdrawing the purified oil produ'ct from the upper portion of said body above the location of fresh adsorbent discharge from said confined streams.

' l2. Amethod for countercurrently contacting a liquid hydrocarbon feed which remains as a liquid during the contacting and a downwardly moving column of adsorbent which comprises, introducing an adsorbent of palpable particle form into a body of contacted liquid hydrocarbons maintained in the upper section of a confined" contacting zone as a confined stream discharging well. below the surface of said body of liquid and causing the adsorbent to fall freely as dispersed particles downwardly through a vertical section of said body onto a column of said adsorbent maintained below said body of contacted hydrocarbon liquid, passing the adsorbent downwardly within said column countercurrently to the liquid hydrocarbon material, withdrawing spent adsorbenf along with some liquid hydrocarbon feed from. the lower section of said column as at least one confined stream, controlling the linear rate of flow in said confined stream sufficiently low to maintain the adsorbent as the continuous phase in said stream by regulating the flow in said stream at a level substantially below where it leaves said column, introducing liquid hydrocarbon feed into the lower section of said column and passing it upwardly therethrough while controlling the velocity of oil flow below a column disrupting. velocity, whereby countercurrent contacting of the hydrocarbon liquid and adsorbent is effected and withdrawing contacted liquid hydrocarbon from said body thereof at a level above that of the adsorbent discharge from said confined adsorbent feed stream.

13. A method for treating oils of low asphalt content to purify the same which comprises, introducing an adsorbent of palpable particulate form into the upper section of a confined treating zone in a plurality of horizontally spaced confined feed streams discharging substantially under the surface of a body of the treated oil maintained in the upper section of said zone, at a plurality of points uniformly distributed across the horizontal cross-sectional area of said treating zone, causing the adsorbent particles to fall freely through a vertical section of said body of oil onto a column of said adsorbent and passing the adsorbent in said column downwardly within said treating zone countercurrently to the liquid oil undergoing treatment, while controlling the velocity of oil flow suificiently low to maintain the solid material as the continuous phase in said column, withdrawing spent adsorbent along with some oil from the lower section of said column as at least one confined stream while maintaining the solid material as the continuous phase in said stream by controlling the flow below that at which the oil would exist as the continuous phase, said control being imposed on said stream at a point substantially below where it leaves said column, introducing liquid oil feed into the lower section of said column and passing it upwardly therethrough as aforesaid and withdrawing treated oil from said body of treated oil above the level of discharge of said confined adsorbent streams thereinto.

14. A method for countercurrently contacting a liquid hydrocarbon feed which remains as a liquid during the contacting and with a downwardly moving column of adsorbent which comprises, introducing an adsorbent of palpable particulate form into the upper section of a confined treating zone as at least one confined feed stream discharging into a body of contacted oil maintained in the upper section of said zone at a point well below the surface of said body and causing the adsorbent to fall freely as dispersed particles downwardly through a vertical section of said body onto a column of said adsorbent maintained below said body of contacted oil, passing the adsorbent in said column downwardly within said treating zone countercurrently to the liquid oil undergoing contacting, while controlling the velocity of oil flow below the column disrupting velocity, withdrawing spent adsorbent along with some liquid oil from the lower section of said column as at least one confined stream, while maintaining the velocity of flow in said stream sufficiently high to maintain the liquid as the continuous phase in said stream, introducing liquid oil feed into the lower section of said column and passing it upwardly therethrough as aforesaid and withdrawing contacted oil from said body of contacted oil above the level of discharge of said confined adsorbent feed stream thereinto.

15. A method for countercurrently contacting a liquid hydrocarbon feed which is maintained as a liquid during the contacting and a downwardly moving column of adsorbent which comprises, maintaining a column of adsorbent of palpable particle-form throughout a substantial portion of the length of a confined contacting zone, maintaining a body of contacted liquid hydrocar-.

bon above said column and open to the column surface, introducing liquid hydrocarbon feed material into the lower section of said column and passing it upwardly therethrough at a rate controlled below that which would interfere with uniform downward flow of adsorbent particles in said column, flowing the contacted liquid hydrocarbon material upwardly within the contacting zone from the surface of said column as said body to effect settling of any entrained adsorbent particles, withdrawing the contacted liquid hydrocarbon material from the upper section of said liquid body, withdrawing wet contacted adsorbent from the lower section of said column as at least one downwardly extending, confined stream of gravitating adsorbent and imposing a fixed flow restriction on said stream to maintain the rate of flow constant, supplying adsorbent to said column by passing it downwardly as at least one confined stream of gravitating particles through at least an upper portion of said liquid body from which confined stream the adsorbent is discharged a substantial distance below the surface of said body of liquid, the adsorbent being in dry condition as supplied to said stream, and adjustably controlling the rate of adsorbent supply to said column before the adsorbent becomes wetted with the liquid hydrocarbon so as to maintain the column surface level substantially constant, the rate being decreased when the column level rises and increased when the column level falls.

16. A method for treating oils of low asphalt content to decolorize the same which comprises, maintaining a column of adsorbent of palpable particle-form throughout a substantial portion of the length of a confined, treating zone, maintaining a body of treated oil above said column and across its entire surface, introducing liquid oil feed into the lower section of said column and passing it upwardly therethrough at a rate controlled below that which would interfere with uniform downward flow of adsorbent particles in said column, flowing the treated oil upwardly within said treating zone from the surface of said column as said body to effect settling of any entrained adsorbent particles, withdrawing the treated oil from the upper portion of said liquid body, withdrawing spent adsorbent along with some liquid oil downwardly from the lower section of said column as at least one confined stream of gravitating material so as to promote downward movement of the particles in said column, imposing a fixed restriction on said stream to limit the flow therein to a constant rate which is suitable for effecting the desired decolorization of said oil feed, passing fresh adsorbent downwardly from a location above said body of treated oil through an upper portion of said body from which adsorbent is otherwise excluded as at least one confined, vertical stream of adsorbent particles which fall freely through an upper portion of said stream and settle freely through liquid oil within a lower portion thereof, said stream having a horizontal cross-sectional area amounting to only a minor fraction of that of said body of oil, discharging the particles from the lower ends of said streams into the open body of treated oil at a level more than six inches below its surface and more than six inches above the surface of said column and permitting the particles to settle freely down through the intervening portion of said body of liquid onto said column, continuously supplying a stream of dry fresh adsorbent to said confined stream and adjustably controlling the rate of flow of said last named stream of dry adsorbent to maintain the column surface within a constant narrow range of levels, the rate being increased to compensate for a drop in surface level and increased to compensate for a rise in surface level and the rate being controlled at all times below the maximum settling velocity of the adsorbent through the liquid oil in the lower portion of said confined vertical stream.

17. In a process wherein a liquid hydrocarbon material is treated by passing it upwardly through a column of downwardly moving adsorbent of palpable particle form in a confined treating zone and the treated liquid is withdrawn from the upper section of said zone, the method for supplying adsorbent to said column and withdrawing treated liquid from said treating zone without substantial entrainment of the adsorbent particles which comprises, maintaining a body of treated liquid hydrocarbon material above said column and entirely across its surface, maintaining a continuously supplied confined column of adsorbent extending downwardly from. a location above said treating zone to a location within the: upper section thereof above. said liquid body,

permitting adsorbent to escape from the lower end of said confinedv column through a plurality of flow restricting apertures distributed around the lower section of said column, flowing the particles issuing from said apertures downwardly over a conical surface to expand the flow and dropping the adsorbent downwardly from the lower end of said conical surface as a laterally confined annular curtain of adsorbent particles falling freely through a confined vertical passage from a location above the surface of said liquid body to a location spaced a substantial distance below the surface of the body of liquid but. spaced above the column of adsorbent therebelow, permitting the adsorbent to settlev from the lower end of said annular passage through the intervening portion of the liquid body onto the surface of the column of adsorbent. therebelow, flowing treated oil upwardly within said treating. zone from the surface of said column of adsorbent as said body of liquid whereby any entrained particles are settled and withdrawing the treated liquid from the upper section of said body above the location of adsorbent discharge from said vertical passage.

18. A method for countercurrently contacting a liquid hydrocarbon feed which is maintained as a liquid during the contacting and a downwardly moving column of adsorbent which comprises, maintaining a column of adsorbent of palpable particle-form throughout a substantial portion of the length of a confined contacting zone, maintaining a body of contacted liquid hydrocarbon above said column and open to the column surface, introducing liquid hydrocarbon feed material into the lower section of said column and passing it upwardly therethrough at a rate controlled below that which would interfere with uniform downward flow of adsorbent particles in said column, flowing the contacted liquid hydrocarbon material upwardly within the contacting zone from the surface of said column as said liquid body to efiect settling of any entrained adsorbent particles, withdrawing the contacted liquid hydrocarbon material from the upper section of said liquid body, withdrawing wet contacted adsorbent from the lower section of said column through a confined passage as a confined, downwardly extending stream of gravitating adsorbent, supplying adsorbent to said contacting zone through a confined passage as a confined stream of gravitating particles extending downwardly through at least an upper portion of said liquid body from which confined stream the adsorbent is discharged a substantial distance below the surface of said body of liquid, adjustably controlling the rate of adsorbent flow through one of said confined passages so as to maintain the column surface level substantially constant, the rate being decreased when the column level rises and increased when the column level falls, while maintaining the flow rate of the adsorbent in the other of said confined passages substantially constant.

19. In a process wherein a liquid hydrocarbon material is passed upwardly through a column of downwardly moving adsorbent of palpable particle form in a confined contacting zone, the method for supplying adsorbent to replenish said column and for withdrawing contacted liquid from said zone without substantial entrainment of the adsorbent particles which comprises, passing the contacted liquid hydrocarbon material upwardly from the surface of said column and through a portion of the confined zone thereabove and withdrawing the liquid from said confined zone at a level spaced substantially above the column surface so that a liquid body of the contacted hydrocarbon material is maintained above the column, introducing feed adsorbent of palpable particle form into said liquid body as at least one confined stream of substantially smaller cross-section than said liquid body, which stream discharges into said body a substantial distance below its surface but above the column surface, whereby a settling space is provided in the liquid body 22 above the; level of adsorbent discharge thereint'o and causing the adsorbent particlesto fall freely through a vertical section of said body of oilinto the column of adsorbent;

20. An apparatus for effecting countercurrent contact of a liquid oil'with a downwardly moving column of adsorbent particles which comprises, an upright contacting vessel, a partition across the lower section of said vessel spaced above the bottom thereof so as to define a plenum chamber, a plurality of uniformly distributed, spaced nozzles in said partition for liquid flow from said plenum chamber to the. portion of the vessel thereabove, aplural-ity of uniformly distributed laterally spaced conduits of adsorbentwithdrawal extending through. said partition and downwardly through said plenum chamber andiIthe bottom of said vessel, means to introduce liquid oil. into said'plenum chamber, a device at a locationalong the upper section of said vessel spaced a substantial distance 'above said partition to measure the surface. of the: column of adsorbent within theupper section of said vessel, a plurality of laterally spaced uniformly distributed, vertical tubes positioned within the upper section of said vessel, said tubes terminating on their open upper ends short of the upper end of said vessel and on their open lower ends at a common level more than six inches above the level of said level measuring device, said tubes having lateral dimensions amounting to only a small fraction of the corresponding dimensions of said vessel so that only a small fraction of the horizontal cross-sectional area of said vessel is occupied by said tubes but the minimum lateral dimension in every direction at any location along each of said tubes being greater than about 3 inches, means to supply adsorbent to the upper ends of said tubes and an outlet for treated liquid oil arranged for withdrawal of oil from the space in said vessel between said tubes at a level below the upper ends of said tubes and more than 6 inches above the lower ends thereof.

21. An apparatus for effecting countercurrent contact of a liquid oil with a downwardly moving column of adsorbent particles which comprises, an upright contacting vessel, a member defining a plenum chamber within the lower section of said vessel, said plenum chamber communicating with the portion of the vessel thereabove only through a plurality of laterally spaced restricted passageways which are uniformly distributed across the horizontal cross-sectional area of said vessel, means to supply liquid oil to said plenum chamber, means to withdraw adsorbent from the lower section of said vessel, a device at a location along the upper section of said vessel to measure the surface level of the column of adsorbent within the upper section of said vessel, a plurality of laterally spaced uniformly distributed, vertical tubes positioned within the upper section of said vessel, said tubes terminating on their open upper ends short of-the upper end of said vessel and on their open lower ends at a common level more than six inches above the level of said level measuring device, said tubes having lateral dimensions amounting to only a small fraction of the corresponding dimensions of said vessel so that only a small fraction of the horizontal cross-sectional area of said vessel is occupied by said tubes but the minimum lateral dimension at any location along said tubes being greater than about 3 inches, a plurality of adsorbent feed pipes extending down through the upper end of said treater, one of said pipes terminating adjacent and in line with the upper end of each one of said tubes and arranged to deliver the adsorbent directly into the upper section of said tubes, said pipes being of substantially smaller cross section than said tubes, and an outlet for treated liquid oil arranged for withdrawal of oil from the space in said vessel between said tubes at a level below the upper ends of said tubes and more than 6 inches above the lower ends thereof.

22. In an apparatus for effecting countercurrent con- 23 tacting of a liquid hydrocarbon and a column of downwardly flowing adsorbent of palpable particle-form in an upright contacting vessel, the improved means for supplying adsorbent to said vessel and withdrawing contacted liquid therefrom which comprises, at least one annular tube, open on its ends, positioned vertically within the upper section of said vessel and below its upper end, at least one adsorbent supply conduit extending downwardly from a supply location above said vessel to a location within the said vessel spaced above the upper end of said annular tube, said conduit having a plurality of apertures distributed around its sidewall near its lower end, a closure member across the lower end of said conduit, a sleeve mounted slidably on the lower section of said conduit and adapted to cover said apertures to any desired extent, means associated with said sleeve for ad- ,justing the same from outside of said vessel, an upwardly and having sides which slope upwardly and inwardly towards and at least as far as the edge of the lower end of said conduit so as to catch all of the adsorbent issuing from said apertures and deliver the same into said annular tube, and an outlet for liquid withdrawal on said vessel at a level intermediate the ends of said annular tube.

References Cited in the file of this patent UNITED STATES PATENTS 2,132,151 Fenske et a1. Oct. 4, 1938 2,412,135 Evans Dec. 3, 1946 2,459,056 Watson Ian. 11, 1949 2,477,281 Bergstrom July 26, 1949 2,490,336 Crowley Dec. 6, 1949 2,552,435 Knox et al. May 8, 1951 2,552,436 Bennett et al. May 8, 1951 2,564,717 Olsen Aug. 21, 1951 2,618,586 Hendel Nov. 18, 1952

Claims (1)

1. A METHOD FOR COUNTERCURRENTLY CONTACTING A LIQUID HYDROCARBON FEED WHICH REMAINS IN THE LIQUID PHASE DURING THE CONTACTING WITH A DOWNWARDLY MOVING COLUMN OF ABSORBENT WHICH COMPRISES, MAINTAINING A COLUMN OF ADSORBENT OF PALPABLE PARTICLE FORM ALONG AN INTERMEDIATE PORTION OF CONFINED, ELONGATED CONTACTING ZONE, MAINTAINING A BODY OF LIQUID HYDROCARBON FEED IN A LOWER PORTION OF SAID TREATING ZONE IMMEDIATELY BELOW SAID COLUMN OF ADSORBENT AND IN LIQUID FLOW COMMUNICATION WITH THE BOTTOM OF SAID COLUMN, SUBSTANTIALLY EXCLUDING THE PARTICLES OF ADSORBENT FROM SAID BODY OF LIQUID MAINTAINING A BODY OF CONTACTED LIQUID IN AN UPPER PORTION OF SAID TREATING ZONE IMMEDIATELY ABOVE AND OPEN TO THE SURFACE OF SAID COLUMN, WITHDRAWING USED ADSORBENT FROM THE LOWER SECTION OF SAID COLUMN WHILE MAINTAINING SAID BODY OF FEED LIQUID FREE OF SAID PARTICLES, REPLENISHING SAID COLUMN AT ITS UPPER END WITH FEED ADSORBENT WHILE SUBSTANTIALLY EXCLUDING THE FEED ADSORBENT FROM AT LEAST THE UPPER PORTION OF SAID BODY OF CONTACTED LIQUID HYDROCAR-

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