US2487795A

US2487795A - Hydrocarbon conversion process

Info

Publication number: US2487795A
Application number: US793000A
Authority: US
Inventors: Louis P Evans
Original assignee: Socony Vacuum Oil Co Inc
Current assignee: ExxonMobil Oil Corp
Priority date: 1947-12-20
Filing date: 1947-12-20
Publication date: 1949-11-15
Anticipated expiration: 1966-11-15

Description

Nov. 15, 1949 EVANS 2,487,795

HYDROCARBON CONVERSION PROCESS Filed Dec. 20, 1947 HOPPER 43 8 COOLER HOPPER 4ND 70 HEATER 6 ON VE ran J 3 our SPF/V7 was SOLVE/VT hF/MES 3e auue'r REMOVAL CONVERTOR PRODUCT REC OVER! SYSTEM /09 IOIV SUPPOR TIA 6 5A5 IN I N V EN TOR. 1.00/5 P EVA/V5 AGE/V7 0/? ATTORNEY Patented Nov. 15, 1949 HYDROCARBON CONVERSION PROCESS .Louis P. Evans, Woodbury, N. J., assignor. to Socony-Vacuum Oil Company, Incorporated, a corporation of New York Application December 20, 1947, Serial No. 793,000

. 1 This invention pertains to a process for conversion of high boiling hydrocarbons at controlled elevated temperatures in the presence of a particle-form contact mass material. This invention is particularly concerned with a process for the conversion of hydrocarbon feed stocks which contain both asphaltic and oily constituents.

Such conversion processes may involve treating, reforming, polymerization, oxidation, desulphurizatidn, cracking, etc., of the hydrocarbons. A particularly important process is the catalytic cracking conversion of hydrocarbons, it being well known, for example, that hydrocarbon fractions boiling above the gasoline boiling range may be converted to lower boiling gasoline containing hydrocarbons upon being subjected to contact with a suitable solid porous catalyst at 8 Claims. (01. 196-52) temperatures of the order of 800 F. and upwards and at pressures usually above atmospheric.

Heretoiore, such conversion processes have been limited to the conversion of a relatively light, clean, substantially tar or asphalt free pctroleum feed stocks because of the tendency of the asphalt containing stocks to cause the formation .of excessive deposits of coky contaminants on the catalyst which deposits cannot be economically removed. In order to avoid these heavy coke deposits which render the cracking process unfeasible, it has been the wide refinery practice to subject some high boiling petroleum feed stocks (when available with a broad boiling range) to'a preliminary tar separation step, separate an easily vaporizable fraction from a liquid fraction which bears the asphaltic constituents and to subject only the vaporizable fraction to catalytic cracking while discarding the liquid tar separator bottoms. Since this discarded fraction may be made up. of a large proportion of valuable oily constituents and a smaller proportion of asphaltic constituents, it is obvious that a large quantity of otherwise acceptable catalytic cracking feed stock is lost and unavailable as such in the prior art tar separator operation. When the crude residuum is not of such boiling range and does not contain substantial amounts of vaporiz-- able gas oil, it has been considered in practice as being unsuitable as such for a cracking charge stock. The problem is becoming increasingly serious due to the fact that relatively low boiling petroleum crudes are becoming less plentiful and the crudes which are most readily available are high boiling crudes in which the oily constituents boil so high as to prevent their separation from asphaltic constituents by distillation process without subjecting them to temperatures at which undesirable thermal cracking and excessive coking occur. As a result, in order to use such high boiling stocks at all, it is necessary first to subject them to a preliminary thermal coking step to provide some lower boiling oily fractions for a subsequent catalytic cracking operation. By-products from the coking process are a heavy liquid out which may contain a substantial amount of oily constituents as well as asphaltic constituents and a very large amount of petroleum coke, the disposal of which often creates a serious refinery problem.

A novel process for conversion of high boiling hydrocarbons which overcomes th above difilculties is described and broadly claimed in my copending application Serial Number 720,271 tiled in the United States Patent Ofiice, January 4:, 1947, now abandoned. In that application the process described is broadly one wherein the by drocarbon feed fraction bearing asphalt and oily constituents is contacted under suitable sorption conditions with a particle-form porous contact material which is suitable for sorbing the oily constituents of the feed in the pores of the contact material while leaving substantially un sorbed the asphaltic constituents of the liquid feed. A substantial separation of unsorbed asphaltic constituents from the contact material bearing sorbed oily constituents is then efiected. The separated contact material bearing sorbed oily constituents is then heated to a temperature suitable for effecting the desired conversion of the sorbed oily constituents. The present inven-- tion deals specifically with an improvement in the above described process wherein the contact material bearing sorbed oily constituents is heated to a temperature suitable for conversion of the sorbed hydrocarbons by contacting it directly with a liquid heat exchange fluid such as a molten metallic alloy. The contact material after sepa ration from the gaseous hydrocarbon conversion products and after separation from the liquid heat exchange fluid is subjected to regeneration to prepare it for reuse.

A major object of this invention is the provision of a process for conversion of the oily constituents in high boiling asphalt bearing hydrocarbon fractions without the formation of prohibitive amounts of coke.

A specific object of this invention is the provislon in a process wherein oily constituents from asphalt bearing petroleum fractions are sorbed on a. suitable porous sorbent, and then converted at higher temperatures in the presence of the sorbent and in the absence oi the asphalt constituents of the petroleum fraction of an improved method for changing and controlling the solvent temperature during the conversion operation.

The size or the sorbent particles employed in the process or this invention is to some extent dependent upon the. variables involved in any particular application of the process. These im- These and other objects of this invention'will portant variables are time or contact between the liquid asphalt bearing charge and the sorbent in the sorption zone, temperature in the sorption zone, viscosity or the liquid charge. and to a lesser extent the ratio-0f liquid oil to sorbent charged to the sorption zone. Increasing time of contact and increasing temperature result in a decrease in the emciency of separation of asphaltic and oily constituents. Decreasing viscosity of the liquid charge has the same effect. On the other hand increasing temperature anddecreasing viscosity both result in more rapid sorption of the percolation of the oils through clay-type adsorb-' ents. The present process is the opposite of the so-called percolation and contact filtration processes for oil refining in that, by the present process, it is the oily constituent and not the asphaltic constituent which is sorbed by the contact material. This fundamental diflerence makes possible the combination cracking process of this invention and permits the elimination of the asphalt materials without contamination of the catalyst thereby. It has been found that porous con tact materials, having a structure corresponding to that of an inorganic oxide gel having a subliquid oily constituents by the sorbent. If the ratio or sorbent to liquid charge is excessive some loss in separation eiliciency results. By proper control of these variables some latitude in the average diameter or the sorbent employed may be provided. However when the diameter of the particles becomes too small, the sorbent preferentially adsorbs the asphaltic constituents from the liquid charge in the same manner as well known oil filtering clays. This is shown in Table I below in which is tabulated the deasphalting results obtained on Mid-Continent residuums using a silicaalumina gel type sorbent having a' bulk density in the 4-8 mesh size range of about 0.7.

Table 1 Experiment Number l 4 5 6 7 2 3 Charge Viscosity, S. U. V 116.9 116. 9 81. 8 81. 8 81.8 81.8 340 Charge. Ramsbottom Carbon. 2.3 2. 3 2.3 2.3 6.1 Mesh Size of Borbent ('gylerL. 30-60 30-60 60-8) 31-60 4-8 4-8 sorption Zone Contact ime... 24 hrs. 24 hrs. 2 min. 2 min. 2 hrs. 72 hrs. 4 his. BOIFHOD Zone, Temperature F... 160 150 150 150 150 75 276 We ght Ratio of Borbent to lliquid Charge 1 1 l 1 1 1 2.2 Properties of Oily Constituents Retained by Borbent alter Washing: v

S, U. 210 F. Sec 09.7 129.2 75.2 81.7 115.4 49.7 161 Ramsbottom Carbon, Per Cent- 1. 8 2. 3 3. l 2. 4 Properties of Materials Washed irom Sorbent Surface:

B. U. V. 210 F. 860 164 100. 1 85. 9 80.5 76.0 139. 2 660 Ramsbottom Carbon, Per Cent 2. 4 2. 2 2. 0 3. 6 6. 7

stantially uniform porosity of low macropore volume with an average por diameter not exceeding about 125 Angstrom units and a particle size preferably larger than that corresponding to about 30 mesh (Tyler) have the ability to sorb the oily constituents of a liquid hydrocarbon traction while leaving substantially unsorbed the asphaltic constituents. Natural and treated clays and bauxites such as are employed in oil filtering and decolorizing processes do not appear to have this property. The macropore volume of the contact material employed in the present invention should be relatively low so that the pore volume is mostly that or micropores. In general, the volume of macropores, that is. those pores having radii larger than 100 Angstrom units, should constitute less than about 30 percent of the total pore volume and preferably 10 percent or less. The measurement oi pore size and pore size distribution in various porous materials is discussed in detail by L. C. Drake and H. L. Bitter in Industrial and Engineering Chemistry, Analytical Edition, volume 17, pages 782-791, 1945. The methods described there were essentiall those employed in determining the bulk densities, aver. age pore diameters, andother pore measurements 01' the adsorbents employed in the present invention.

when the contact periodwas 24 hours (Experiment 4) or even 2 hours (Experiment 7 the sorbent acted similar to a normal filtering clay and preferentially adsorbed the asphaltic constituents. But when the contact time was reduced to two minutes (Experiment 5) the 30-60 mesh sorbent exhibited a preference for the oily constituents over the asphaltic constituents.

When particle size was reduced below 60 mesh,

the sorbent preferentially adsorbed the asphaltic constituents even at very low contact periods (Experiment 6).

The effect of' contact time and temperature is shown in Table II below in which are presented the deasphalting results on an East Texas residuum having an original Saybolt Universal viscosity of 512 seconds at 210 F. and a Ramsbottom carbon residue of 11.1. In this experimeat a silica-alumina gel type sorbent of 4-8 mesh size and 0.48 bulk density was employed.

In general it may be said that the particle size of the sorbent material particularly in the case of inorganic oxide gel type sorbents should be greater than that corresponding to about 60 mesh Tyler and preferably within the range about 0.022 to 1.0 inches average diameter, The

size ranges given although the results will be less satisfactory. It is contemplated that in its broader aspects this invention covers these latter operations as well as the operations within the specified preferred limits.

The porosity of the gel particles employed in the process of this invention is of fundamental importance. The degree of. porosity is generally reflected in the bulk density of the gel composite used; the lower the bulk density, the greater being the degree of porosity. For the purposes of the present process, porous sorbent particles having bulk densities of between about 0.4 and 1.1 gram per cubic centimeter are preferred. The bulk densities indicated correspond to an average pore diameter of between about 20 and about 125 Angstrom units. Preferably, the sorbent used will have a bull; density between about 0.6 and about 0.8 gram per cubic centimeter. Gel particles having a bulk density greater than about 0.8 have been found to have excellent selectivity but poor sorbing capacity, while particles with a bulk density less than about 0.6 have relatively poor selectivity. However, since the selectivity of the deasphalting process improves with a decrease in temperature, particles with a bulk density less than 0.6 would be satisfactory for deasphalting stocks which can be processed at low temperatures.

The degree of porosity of a synthetic inorganic oxide gel will, in general, depend on the conditions under which it is prepared and allowed to set to gelation. A particularly convenient method of preparing gel particles used in the process of this invention is described in U. S. 2,384,946, issued September 18, 1945, to Milton M. Marisic. It is there disclosed that spheroidal particles of inorganic oxide gel may be prepared by mixing an acidic stream of sodium silicate and allowing the resulting sol to be ejected from a nozzle into an oil column, where the gel sets in the form of bead-like spheroids. The resulting gel spheres, after washing, drying and tempering, were of a size varying between about 4 and about 20 mesh. The gel beads so produced had a bulk density of between about 0.4 and about 1.1 and an average pore diameter of between about 20 and about 125 Angstrom units. They proved to be excellent selective absorbents Ior use in the process of this invention.

Likewise, irregularly shaped porous absorbent fragments or particles having the structure of inorganic oxide gels may be used. However, in general, spheroidal particles are to be preferred, since attrition losses are then at a minimum and contamination with gel fines of the asphalt-bearing stock is substantially eliminated.

In general, siliceous gel particles will be used in the process of this invention, such as silica gel, silica-alumina gel, silica-zirconia gel, silicathoria gel, silica-magnesium oxide gel and the like. Porous sorptive silica glasses having a structure approaching that of a siliceous gel likewise are contemplated for use in the process descrlbed'herein, it being necessary, however, that the porous glasses employed have an average pore diameter less than about Angstrom units, and a macropore volume of less than about 30 percent of the total pore volume.. The size of the porous glass particles must also be carefully controlled so as to obtain preferential sorption of the oily constituents. Usually particles of less than 60 mesh size are undesirable. It is also contemplated that within the scope of this invention other porous materials not of the inorganic oxide gel composition which have structures approaching that of a siliceous gel and are within the above specified pore size and particle size limits may be employed within the scope of this invention.

Typical of the porous glasses used are those described in U. S. 2,106,744, issued February 1, 1938, to Hood et al. There it is disclosed that a silica-alkali-borlc oxide glass of suitable compositlon is prepared by a fusion process. Heat treatment of this glass results in separation of the glass into two phases; one phase is rich in alkaliboric oxide and is soluble in acids, while the other phase, which is insoluble in acid, consists of silica with a small amount of boric oxide. Extraction of this heat treated glass with acid results in a porous silica glass which can be employed as a porous absorbent separating medium in accordance with the present invention.

The liquid heat exchange fluid employed in this invention may be a suitable inorganic salt melt or preferably a molten metal or metallic alloy having a boiling point substantially above the highest temperature at which it is employed in the process and having a melting point substantially below the desired hydrocarbon conversion temperature. The heat exchange fluid should be oxygen-insensitive and should have a sumciently high surface tension to avoid appreciable wetting of the contact material involved. It will be apparent that the proper choice of the heat exchange liquid will be dependent upon the particular conversion conditions and catalyst material involved in any given application of the invention. As an example, where the reaction involved is a catalytic cracking conversion of hydrocarbons occurring at temperatures of the order of 800-1000 F., molten lead orzinc may be employed or some metallic alloy having a melting point below about 750 F.- 800 F. and having a low vapor pressure at 10001100 F. An example of such an alloy is one consisting of 50 percent lead and 50 percent sodium which has a melting point of about 627 F. Exemplary of inorganic salt melts which may be employed when the reaction involved is catalytic cracking is cuprous chloride melting at about 788 F. The melting point of this salt melt may be reduced by the addition of alkali metal chloride in small amounts. For higher temperature reactions a suitable fluid is a mixture of 50 percent lithium sulphate and the balance of approximately equal parts of the sulphates of sodium and manganese, which mixture melts at about 875 F. When the reaction involved is a low temperature treatment or molecular rearrangement of the sorbed hydrocarbons, a low melting point alloy'may be employed such as a mixture of 50 percent tin and 50 percent lead melting at about 429 F.

The invention may be most readily understood by reference to the attacheddrawing which is a schematic arrangement of the system of this invention in which the apparatus is shown partially in section. In the drawing, vessel 20 is a deasphalting chamber which may be of rectangular or any other desired cross-sectional shape. A partition 24 across the upper section of chamber 20 defines a solid inlet surge chamber 25 in its upper end. Tubes 26 depend from partition 24 for flow of contact material from chamber 25 onto the surface of the substantially compact contact material column maintained in the sorption section 28 of the deasphalting vessel. Particle form contact material having a catalytic.

activity for the desired conversion and being suitable for sorbing the oily constituents of a liquid feed while leaving substantially unsorbed the asphalt constituents thereof is cooled to a suitable temperature in hopper 29 positioned above vessel 20 and then passed via conduit 2| into vessel 20 to keep replenished the column of such material in section 28 of vessel 20. -A hydrocarbon feed stock which contains both asphaltic and oily constituents, for example a heavy petroleum residuum fraction or a tar separator bottoms fraction, is introduced into chamber 20 from manifold In via headers I l, closed on their ends, which extend into space 30 and nozzles l2 which are spaced along headers II. The liquid charge distributes itself over the surface 21 of the contact material column and percolates downwardly within the column, whereby the oily constituents become sorbed in the pores of the contact material and the asphalt constituents remain substantially unsorbed. The contact material bearing sorbed oily constituents and the unsorbed liquid are withdrawn together from the bottom of vessel 20 through duct 22 at a suitable rate controlled by the valve 3|.

The mixed liquid and solid material are directed by duct 22 onto an endless foraminous moving belt l4 supported over horizontally spaced pulleys l5 and IS, the latter of which is rotated by means of drive motor H. The drain duct 22 and valve 3| therein may extend horizontally substantially the width of belt l4 so as to uniformly distribute solid material and liquid across the belt. Suitable guards (not shown) may be provided within chamber 35 along the opposite sides of the belt I4 to prevent solid particles from falling off the sides. A drain pan i8 is supported on its opposite sides from the wall of chamber 35 between the pulleys l5 and I6 and below the belt l4 so as to receive liquid which drains therethrough. The drained liquid containing the asphalt constituents is withdrawn from pan [8 via conduit l9 to the asphalt receiver 32. Entrained solid fines may be removed from the bottom of receiver 32 by means of outlet 33 and asphalt may be withdrawn via conduit 34 to pump 36. The asphalt containing liquid then may be entirely pumped from the system via conduits 31 and 38 or in part recycled via conduits 31 and 39 to inlet manifold l0 feeding the deasphaltlng chamber.

In some operations such recycling is desirable in order to reduce the' amount of oily material in the finally discarded asphalt constituents to a minimum.

The contact material is carried along on belt M in the direction of the flow arrows and the contact material from which most of the unsorbed liquid has been separated by draining is discharged from the belt I4 into the washing chamber 40. The chamber 40 communicates on its lower end with the boot section of a bucket elevator 43. In elevator 43 buckets 44 hav n perforated bottoms are moved upwardly and downwardly on endless chain 45 so as to transfer the washed contact material from the elevator boot section upwardly to duct 350 feeding supply hopper 43 which in turn feeds the hydrocarbon convertor 41. The bottoms of the elevator buckets 44 are perforated, the perforations being, of such size as to retain the contact material particles while permitting liquid to pass therethrough. The elevator casing is inclined and the buckets are so shaped that liquid which drains from any given upwardly moving bucket does not fall into the bucket moving upwardly therebelow, but is delivered back to the elevator boot' section. A suitable washing solvent such as a naphtha, kerosene, benzol or light gas oil fraction may be introduced from an outside source through conduit 42 into conduit 48 through which it passes into the elevator boot section. The solvent passes from the elevator boot section into the lower section of chamber 40 via passage 49 and then passes upwardly through the washing chamber to be withdrawn from the upper portion thereof through conduit 50 to a Washing solvent receiver 5|. Baflles 52 provide a zig-zag passage in chamber 40 through which the contact material passes as it descends through the bath of upwardly moving washing solvent. The solid particles are in this manner subjected to a quick wash under conditions so controlled as to accomplish the removal of asphalt containing liquid adhering to the outer surfaces of the contact material particles without substantial separation of the sorbed oily constituents from the contact material. A relatively small amount of washing solvent may also be sorbed by the contact material during the washing operation. The washed contact material may thus contain a substantial amount of sorbed oily constituents from the original feed, a relatively small amount of washing solvent (and in some casespractically no washing solvent) and in some instances small amounts of asphalt constituents from the feed. It should be understood that while the gel type contact material particles of the type described have the unusual characteristic of sorbing oily constituents rather than asphalt constituents from high boiling feeds, nevertheless, in the case of some feed fractions the gel type catalyst will also sorb relatively small amounts of asphalt materials. It has been found that this relatively small amount of sorbed asphaltic materials will not increase the coke deposits on the catalyst to prohibitive levels. It should be understood that in claiming this invention in the expressions while leaving the asphalt constituents substantially unsorbed"; or contact material suitable for sorbing substantially only the oily constituents of the liquid feed and in like expressions the 1 word substantially is intended to allow for these relatively small amounts of asphalt constituents which may in some operations be sorbed along with the much larger amount of oily constituents in the contact material pores.

The washed contact material bearing sorbed oily constituents may be passed from the convertor supply hopper converter 41 as a substantially compact, elongated gravity feed leg flowing downwardly in conduit 55. Within the upper section of convertor 41 a horizontal partition 55 is positioned so as to define a seal chamber 51 in the upper end of the converter. It is into this seal chamber 51 that the contact material feed is delivered.

A suitable inert seal gas such as steam or flue gas may be introduced into seal chamber 51 at a rate suflicient to maintain a gaseous pressure therein above that in the conversion section of 46' into the upper end of l space above the moving bed sorbent in the lower portion of the drain chamber. The partition 13 extends horizontally entirely across chamber 10 thereby providing a purge zone I50. A'

purge gas inlet pipe 18 connects into the top 14 above the space 15. A sorbent discharge pipe 82 connects into the lower end of purge zone I50 preferably a substantial distance above the plate from manifold 65.

vessel 41. Conduit I30, diaphragm valve I3I and differential pressure control instrument I82 are provided for this purpose. A plurality of uniiormly spaced vertical conduits 58 serve as a passage for solid flow from seal chamber 51 onto the column 59 of contact material maintained in a lower section of the converter. A horizontal liquid distributing plate 80 is positioned across the vessel 41 shortly above the lower ends of pipes 58. The plate 60 has therein a plurality of uniformly spaced orifices GI which are of smaller diameter than the sorbent particles but of sui'flcient size to permit flow of liquid therethrough. Two header pipes 62 and 53 closed on one end thereof extend across the space 64 between pipes 58 and substantially above the plate 80. These pipes connect outside the vessel into heat exchange fluid inlet manifold 55 and have a number of nozzles 66 spaced along their length for delivery of liquid into the space 64 above plate 50. The liquid supplied from nozzles 56 passes through the orifices 6i and percolates down through the column 59. The rate of liquid heat exchange fluid supply is limited so as to maintain the column 59 in a non-flooded condition. The rate of liquid heat exchange fluid supply may be so limited either by proper design oi the number and size of the orifices GI or by throttling at valve 61 on manifold 65. A pertition 58 is provided across the lower section of convertor 41 and a plurality of uniformly distributed pipes 69 depend from partition 68 for delivery of the used contact material and liquid heat exchange fluid into the drain chamber 10. The partition 68 is so shaped as to provide funnel shaped approach passages to each of the pipes 89 so as to avoid pockets of stationary solid material. The pipes 69 are of substantial length so as to provide a gas-solid disengaging space 85 above the bed of solids in the drain section. A gas outlet 85 connects into the vessel so as to communicate with space 85. The drain chamber 10 is of expanded cross-sectional dimension and is provided with a perforated bottom plate 1i which extends across chamber 10 at a slope greater than about 35 degrees. The top 14 of chamber 10 is substantially parallel to the plate 1|. While the vessel 41 above the drain chamber 10 may be of circular or rectangular cross-sectional horizontal shape, the passage for solid flow along plate 1i as seen along line 2-4 should be preferably of rectangular shape. The orifices 12 in plate 1! are of suflicient size to permit the liquid heat exchange fluid to drain freely therethrough but of insuflicient size to permit passage of sorbent particles therethrough. A vertical plate partition 13 depends from the top 14 of chamber 10 and terminates at a level above the plate 1I so as to provide a gas distributing 1I. Below the plate 1I there is provided a closed sump chamber 80 having a bottom outlet 8I.

In operation relatively cool contact material bearing sorbed oily constituents at a temperature of the order of 400600 F., for example, is supplied onto column 59. A suitable hot liquid heat exchange fluid is supplied into space 64 The heat exchange fluid exists at a temperature substantially above the desired hydrocarbon conversion temperature and its rate and temperature of supply are so controlled as to heat the sorbent to and maintain it within a suitable narrow range of hydrocarbon conversion temperatures. For example, molten lead may pass downwardly through orifices BI onto column 59 at a temperature of about 1050" F. and at a rate suiflcient to control a temperature of about 830 F. at the level of conversion zone drain pipes 89. The rate of lead flow is controlled below that which will flood the voids in the column 59 so as to leave adequate space for flow of liberated gaseous hydrocarbon products down through the column. The lead, sorbent and gaseous conversion products all pass through pipes 69 at the lower end of the conversion zone. The gaseous products are disengaged from the solid sorbent and liquid heat exchange fluid in space 85 and are withdrawn via pipe 88 to a suitable product recovery system 81 which may be of conventional type in the industry. In connection with the gaseous products it will be understood that the word "gaseous" as used herein in describing and in claiming this invention is intended in the sense of covering materials which are in the gaseous phase under the particular operating conditions involved regardless of the normal'phase of those materials under atmospheric conditions. For example, gaseous conversion products leaving the convertor through circuit 86 at a temperature of the order of 800 F. to 950 F. and say 10 pounds gauge pressure may exist substantially entirely in the gaseous phase under these conditions although gasoline, gas oil and heavy fuel oil constituents maybe present which are ordinarily liquids under atmospheric conditions. In drain section 10, the liquid heat exchange fluid settles from the bed of sorbent and passes through orifices 12 into sump 80. The sorbent is purged free of any residual gaseous hydrocarbons or liquid heat exchange fluid by the introduction of a suitable purge gas such as steam or flue gas via pipe 16. The purge gas passes down through the bed of sorbent and through orifices 12 and is removed from the upper portion of sump via pipe 88. A suitable balile 89 may be provided to prevent entrainment of liquid heat exchange fluid in the effluent purge gas stream. A body of liquid 90 is maintained within the bottom of sump 80 so as to prevent escape of gas through the heat exchange fluid outlet M. The purged sorbent passes via pipe 82 to conveyor by which it is transferred to duct 96 supplying the regenerator catalyst surge hopper 98. The rate of sorbent withdrawal from the purge zone I50 is controlled by a suitable flow control valve I02 on pipe 82. Lead now existing at a temperature of the order 11 of 825 F., for example, is pumped by pump 9| through pipe 92 to a heat exchanger I30 where it is again heated. The heated lead may pass via pipes I33, I34, I35 and 65 back to the convertor 41, or it may pass via pipes I33 and I36 to heater I31 wherein its temperature is further raised before it passes to the convertor via pipes I44 and 65. Alternately, the exchanger I30 may be bypassed entirely in which case the lead passes via pipes 92, I39, I34 and I36 to heater I31 and then via pipes HI and 65 to convertor 4'I. Valves are provided on the above pipes to permit control of the lead flow in the manner described.

The used contact material which is supplied to the regenerator surge chamber 98 has lost a substantial part of its catalytic eifectiveness due to the deposition of a carbonaceous contaminant thereon. The regenerator shown in the drawing is of the multi-stage variety which is described and claimed in application Serial Number 447,432, filed in the United States Patent Oifice June 17, 1942, now Patent No. 2,417,399, and application Serial Number 447,433, filed in the United States Patent Ofilce June 17, 1942,

nowPatent No. 2,436,780, in which applications the present applicant is one of the applicants. In general the regenerator 91 is divided into a vertical series of alternating burning and cooling stages. Separate gasinlets 99, I00, IM and I02 and separate gas outlets I04-I0I inclusive spaced vertically from the inlets, are provided for the burning stages. The gas inlets are supplied by a combustion supporting gas such as oxygen, air or mixtures of air and flue gas, from inlet manifold I08. Flue gas passes from the burning stages through outlets I04-I0I and is manifolded into outlet flue I09. Heat transfer tubes or coils may be suitably spaced within the cooling stages. Pipes II are inlets to these tubes and pipes III are outlets therefrom. The inlet pipes II 0 connect into an inlet manifold H2 and the outlet pipes connect into an outlet manifold H3. The hot heat exchange fluid from manifold II3 passes via pipe I I4 to heat exchanger I30 wherein it gives up its heat to the fluid entering via pipe 92. For example, heat exchange fluid from the regenerator existing at about 1050 F. may be cooledin exchanger I30 to about 830 F. The cooled fluid passes via pipe I45 to a cooler I46 wherein it is further cooled before passing via pipe I41, pump II! and pipe II8. back to the inlet manifold II2. In this manner a large por- 12 in hopper 43 through conduit I0. The heat recovered from the final cooling ofthe regenerated contact material may thereby be utilized for partially heating the cooler, oily constituent bearing contact material in hopper 40. The heat exchange fluid, relieved of its heat in hopper 40 may be withdrawn from the tubes therein through conduit 1| and reintroduced into the tubes in hopper 29 through conduit 99. A pump tion of the heat liberated on regenerating the sorbent material may be used for heating the sorbent within the convertor 41. The regenerator heat exchange fluid may take any of a number of .forms such as a suitable gas under pressure or fused metallic oxides or mixtures of certain fused inorganic salts.

Hot regenerated contact material is withdrawn from the lower end of regenerator 91 through outlet H9 at the desired rate as controlled by throttle valve I20. The hot regenerated contact material is then transferred by conveyor I2I to hopper 29 where it is cooled to a temperature at which it may be reused in the deasphalting operation. The regenerated contact material in hopper 29 is cooled to a temperature suitable for its introduction into deasphalting chamber 20 by means of a suitable heat exchange fluid introduced at 68 and removed at 59. If desired, heat transfer tubes may be provided in both hoppers 29 and 46; and the heat exchange fluid withdrawn from the heat transfer tubes in hopper 29 via conduit 69 may be introduced into the tubes I2 may be provided to cyclically circulate the heat exchange fluid and an exchanger I3 may be provided to permit any heat adjustments that may -be required by the desired contact material outlet temperatures from hoppers 29 and 40. Heat may either. be added or withdrawn by means of exchanger I3 as the particular operation involved requires;

While the system described hereinabove is one of the preferred forms of this invention. it should be understood that the various elements making up the particular combined system described are shown in highly diagrammatic form in the drawing and that'the invention is not intended to be limited to the par icular detailed construction of the various elem nts as shown. For example, while it is preferre to percolate the liquid charge downwardly throug a column of the gel particles in the deasphalting chamber, nevertheless it is contemplated that within the scope of this invention the contacting of the gel particles and the liquid charge may be accomplished in a number of other ways and any method which permits the desired contacting is considered to be within the scope of this invention. For example, the liquid charge and the gel particles might be merely charged to a batch type mixer provided with suitable mechanical mixing devices and after suitable mixing has been accomplished, the material may then be discharged from the mixer to a suitable liquid solid separator. Likewise other methods and apparatus than that described hereinabove may be employed to effect separation of unsorbed liquid material from the contact material bearing sorbed oily constituents.

For example, a rotary type filter provided with suitable means for accomplishing both filtering oil of unsorbed liquid and washing of the contact material may be employed. In some operations the washing step may be eliminated entirely and the combination of draining and purging of the contact material with a suitable purging gas may be relied upon to separate the contact material from unsorbed asphalt containing liquid. Moreover, while in the system described he einabove the washed contact material was partially heated and then charged through a gravity feed leg to the converter, it is contemplated that the preliminary partial heating step may be eliminated and all of the heating accomplished within the convertor. Also suitable forced feed devices may be substituted for the gravity feed leg in less preferred forms of the invention as means of introducing the contact material bearing sorbed oily constituents into the convertor. It is also contemplated that the convertor and regenerator construction may be materially different from that shown in the drawing. Other suitable means for disengagement of gaseous products from the solid sorbent and the liquid heat exchange fluid may be employed. Also means other than that shown may be provided foraccomplishing the separation of the heat exchange liquid from the used solid sorbent as will be apparent to those skilled in the art. The regenerator may be of the single stage type or of tical and desirable in order to prevent undue attrition of the contact material to handle the contact material as a substantially compact moving bed or column in the convertor and regenerator and to convey it between vessels by continuous bucket elevators. However, within the broader scope of this invention it is contemplated that the contact material may move in suspension in the liquid heat exchange fluid in the heating and conversion zone and in the gaseous regeneration agent in the regeneration zone; and that means other'than bucket elevators may be employed for transferring the contact material irom one zone to another. It is further contemplated that within its broader scope the method of this invention may involve a substantially in situ process wherein the contact material remains permanently in one or more vessels. For example, the deasphalting, draining, washing, heating conversion and catalyst regeneration and cooling steps may be conducted in proper cycle in a single chamber in which the contact material particles remain as a fixed bed. In the case of operation of the latter type the contact material is heated by percolating a hot liquid heat exchange fluid through the fixed bed of sorbent bearing oily constituents until the desired conversion of the hydrocarbons has occurred. Thereafter the bed is purged substantially free of heat exchange fluid and a stream of air is passed through the bed to accomplish the regeneration. If desired a liquid heat exchange fluid may be percolated through the fixed bed during regeneration to remove the liberated heat. After the regeneration a separate heat exchange liquid may be percolated through the bed to cool it to a suitable temperature for the deasphalting step. Such an in situ operation may be conducted in a battery of side by side vessels containing fixed sorbent beds. The operation of the several vessels may be regulated so that a different step of the cyclic operation is being conducted in each vessel at any given time. The heat exchange fluid passing from a vessel in which the catalyst is being regenerated may be passed through the catalyst bed in a vessel in which the heating step is in progress, and from the latter vessel the heat exchange fluid may return to the bed undergoing regeneration. A batch type operation wherein the contact material is moved periodically, batch-wise from zone to zone is also contemplated.

It will be understood that the desirable conditions of operation during the deasphalting, washing, conversion and catalyst regeneration and cooling steps will vary depending upon the particular liquid charge stock involved and the conversion reaction involved and the particular conversion products desired. Certain general conditions of operation must, however, be observed.

' temperature.

14 decreases. The desirable sorption temperature has been found to var from below room temperature to about 500 F. depending on the liquid traction treated. The temperature of the hydrocarbon liquid charged into the sorption zone and the contact material supplied thereinto should be both adjusted to provide the desired sorption The contact material should not be permitted to contact the-asphalt containing liquid feed at temperature at which substantial thermal coking of the liquid fraction would take place. This means that in general the contact material should be cooled in hopper 29 of Figure 1 for'example, to a temperature which is at least below about 750 F. The pressure in the sorption zone may conveniently be within the order of atmospheric to 50 pounds per square inch. The residence time of the contact material within section 28 of chamber 20, i. e. the sorption zone,

may vary from about l-l0 hours depending upon the liquid fraction involved, the temperature and the ratio of the contact material to the liquid charge. .In many operations it is desirable to control the residence time of the contact material in chamber 20 by means of valve 3| such as will permit substantial saturation of the contact material with sorbed oily constituents.

The ratio of contact material to liquid charge to the deasphalting chamber may vary from about 0.5 to 20 parts by weight of contact material per part of liquid asphalt bearing charge and preferably from about 2 to 6 parts of contact material per part of liquid charge.

The amount of solvent employed in the washing operation may vary depending upon the characteristics of the solvent and of the 'unsorbed liquid involved. In general the contact material washing should be a relatively quick wash so controlled as to prevent removal by the solvent of substantial amounts of sorbed oily constituents from the contact material. The amount of solvent employed may be of the order of 0.25 to 2.0 volumes of solvent per volume of contact material. In some operations the purging step following the washing step may be omitted but when this step is employed the purging gas employed should be a gas which is not apt to cause oxidation of the oily constituents during the conversion, unless of course, the conversion process in-, volved is a partial oxidation process. Steam, nitrogen, flue gas and low molecular weight hydrocarbon gases are suitable purging gases for most operations.

As an example of the separation obtainable in the deasphalting step of this process, the treatment of an East Texas crude bottoms fraction having an A. P. I. gravity of 15.0 at 60 F., a Saybolt Universal viscosity of 512 seconds at 210 F., a pour point above F., and a Conradson carbon residue of 11.1 percent may be considered.

The vacuum assay distillation of this feed fraction was as follows:

F. I, B. P 880 10% 964 30% 1026 40% 1054 47% 1082 This feed fraction was contacted in a suitable confined chamber with a silica-alumina, spheroidal gel catalyst prepared by the method described in United States Patent 2,384,946 issued September 18, 1945 to Milton Marisic. The catalyst unpacked density was about 44 pounds per in the range 4 to 16 mesh by Tyler standard screen analysis. The catalyst had been regenerated until the residual carbon thereon was below 0.5% by weight. During the operation the temperature was maintained at about 275 F. and the pressure was substantially atmospheric. The ratio of liquid to catalyst charge to the sorption zone was about 332 parts by weight of catalyst per part by weight of liquid charge. The

residence time within the sorption zone was about 240 minutes. The unsorbed liquid was recycled until substantially all of the oily constituents had been removed therefrom. Finally a tar fraction amounting to about 30 percent by weight oi the liquid charge was separated from the catalyst bearing sorbed oily constituents and the catalyst was washed with about half of its weight oi Stoddard solvent, the residence time of the catalyst in the washing operation being limited to about 3 minutes. The catalyst after washing contained about 22 percent of its original weight of sorbed oily constituents which represented about 70 percent by weight of the original liquid charge. The catalyst bearing oily constituents was then heated to a temperature suitable for the cracking conversion oi the sorbed oilyconstituents in a confined conversion zone. An an-' alysis of the sorbed oilyconstituents before conversion was as' follows: A. P. I. gravity 17.1; viscosity (K. V.) at 210 F.-46; pour point above 120 F., and Conradson carbon residue 5.7% by weight,

When the contact material bearing sorbed oily constituents is partially heated before introductionto the conversion zone as shown in Figure 1, it should be heated only to a temperature which is substantially below the desired conversion temperature. Usually a temperature of the order of 750 F. is the maximum temperature to which the contact material should be heated in hopper 46 of Figure 1. As has been pointed out, the contact material introduced to chamber 20 should be below about 750 F. so that regenerated contact material in hopper 29 of Figure 1 should be cooled to a level at least below about 750 F.

The operating conditions within the converter M will vary depending upon the activity of the catalyst employed, the particular petroleum charge involved, the reaction involved and the products desired. In general it has been found desirable to maintain the pressures within av range varying from sub-atmospheric to about 200 pounds per square inch. Pressures of the order of to 50 pounds per square inch gauge are preierred. The temperature for the conversion for cracking operations may vary from about 750 F. to 1100 F., temperatures of the order of 850 to 1000 F. being preferred where gasoline is the desired product. Where noncondensable gases are the principal desired product somewhat higher-temperatures may be employed. The ratio of contact material to hydrocarbon throughput may vary from about 1.0 to 40 parts by weight of contact material per part of hydrocarbon charge.

The rate of liquid heat exchange fluid charge to the conversion zonewill vary dependent upon the heat requirements of the particular operation involved. As an example, in the catalytic cracking of hydrocarbons an inorganic oxide gel catalyst having a density of about 40 pounds per cubic foot may be employed. The reaction temperature may be of the order of 8501000 F. with the catalyst entering the conversion zone at from said contact material and said liquid heat about 400 F.'carrying about 30 percent by weight sorbed oil and'leaving the conversion zone at.

about 850 F. Lead may be percolated through the catalyst bed at a rate within the range about 20 to pounds of lead per pound oi catalyst throughput, for lead supply temperatures of the order of 1200-950 F. respectively.

In the contact material regenerator, pressure of the order of.atmospheric to about pounds per square inch may be employed, pressures around atmospheric being preferred. The contact material temperature should be controlled below a heat damaging level by removal of heat therefrom during the course of the contaminant burning. The heat damaging level is that level at. which and above which the contact material suflers permanent loss in catalytic effectiveness for the conversion involved or loss in sorptive efliciency. The heat damaging temperature may vary from temperatures above about 1150" F. to temperatures above about 1450" F. depending upon the particular gel type catalyst involved.

It should be understood that the details of apparatus construction and arrangement, of operating conditions, and of applications of the process of this invention given herelnabove are intended merely as illustrative and it is not intended that the scope of this invention should be limited thereto or limited otherwise except as it may be limited in the following claims.

I claim:

-1. A process for conversion of oily constituents in asphalt bearing hydrocarbon liquid feeds which comprises: contacting the hydrocarbon feed with a suitable solid sorbentmaterial for sorbing the oily constituents, said sorbent being one in which more than about '70 percent of 'its pores are micropores, controlling the size of the sorbent particles and the contact time and temperature and the relative amounts of liquid and sorbent contacted to effect sorption of the oily constituents into the pores of said sorbent while leaving substantially unsorbed the asphalt constituents, the size of sorbent particles employed being larger for longer contact periods and higher contact temperatures, separating the sorbent bearing sorbed oily constituents from the unsorbed asphalt constituents, and contacting said sorbent directly with a hot liquid non-wetting heat exchange fluid to heat said sorbent to a temperature suitable for the desired conversion of the oily constituents.

2. A process for conversion of high boilin oily constituents in asphalt bearing hydrocarbon fractions to lower boiling products which comprises: contacting said liquid fraction for a suitable time and at a suitable temperature with a porous solid contact material in which the particle size is greater than about 60 mesh size and in which most of the pores are micropores and the volume of pores having radii larger than about 100 Angstrom units is less than about 30 percent of the total pore volume to effect the sorption of the oily constituents of said feed in the pores of said contact material while leaving the asphalt constituents substantially'unsorbed; effecting a substantial separation of the unsorbed liquid from the contact material which bears the sorbed oily constituents, and passing a suitable hot, nonwetting liquid heat exchange medium into direct contact with said contact material to heat it to a temperature suitable for conversion of said sorbed oily constituents to lower boiling products, separating the lower boiling hydrocarbon products 17 exchange medium. separating said liquid heat exchange medium from said contact material, reheating said heat exchange medium and again passing it into contact with contact material bearing sorbed oily constituents.

3. A process for the conversion of the oily constituents of high boiling liquid asphalt containing hydrocarbon feeds which comprises: contacting said liquid feed for a suitable time and a suitable temperature for oily constituent sorption with a porous particle-form inorganic oxide gel-type contact material in which most of the pores are micropores and the volume of pores having rdii larger than about 100 Angstrom units is less than about 30 percent of the total pore volume and in which the particles are greater than about 30 mesh size, to effect the sorption of the oily constituents of said feed in the pores oi said contact material while leaving the asphalt constituents substantially unsorbed; eflecting separation of the non-sorbed asphalt containing liquid from said contact material containing sorbed oily constituents, passing said contact material containing sorbed oily constituents through a confined conversion zone in admixture with a sufllcient amount of hot liquid heat exchange fluid to heat it to a temperature suitable for the desired conversion of said sorbed oily constituents, said liquid heat exchange fluid being incapable of substantially wetting said contact material, separating converted hydrocarbon fluid products from said contact material and liquid heat exchange fluid, separating the used contact material from said liquid heat exchange fluid, passing said used contact material through a confined regeneration zone while contacting it with an oxygen containing gas to burn off contaminant deposits and thereby regenerate said contact material, cooling the regenerated contact material to a temperature suitable for its use in contacting said asphalt bearing liquid feed and reusing the cooled contact material for contacting asphalt bearing liquid feed as aforesaid, heating the liquid heat exchange fluid after its separation irom said used contact material and returning the heated liquid heat exchange fluid to said conversion zone to heat said contact material as aforesaid.

4. A process for conversion of high boiling oily constituents in asphalt bearing hydrocarbon fractions to lower boiling products which comprises: contacting said liquid fraction with a porous particle form inorganic oxide gel-type catalyst in which most of the pores are micropores and the volume of pores having radii larger than about 100 Angstrom units is less than about 30 percent and in which the particles are greater than about .022 inch average diameter to efl'ect sorption of the oily constituents of said fraction in the pores of said catalyst while leaving the asphalt constituents substantially unsorbed, efiecting separation of said catalyst bearing sorbed oily constituents from the non-sorbed asphalt version zone, separating the liquid heat exchange a medium from the used catalyst upon which a carbonaceous contaminant has been deposited, passing the used catalyst through a confined regeneration zone while contacting it with a combustion supporting gas to burn off said carbonaconstituents, passing said catalyst bearingIsorbed ceous contaminant, controlling the temperature of said catalyst below a heat damaging level in said regeneration zone, cooling the regenerated catalyst to a temperature suitable for its use in contacting said asphalt bearing liquid fraction,

re-using the cooled catalyst for contacting said asphalt bearing liquid as aforesaid, heating the liquid heat exchange medium after its separation from said used catalyst to a temperature substantially above the desired hydrocarbon conversion temperature and returning said heated liquid heat exchange medium to said conversion zone.

5. A process for conversion of the oily constituents present in a liquid hydrocarbon feed stock containing both oily and asphaltic constituents at elevated temperatures in the presence of a particle-form contact mass material which process comprises: contacting the liquid charging stock in a confined deasphalting zone with a particle-form porous contact material having the pore structure of an inorganic oxide gel in which the total pore volume is taken up mostly by micropores, there being less than about 30 percent pores having radii larger than about Angstrom units, the contact material being made up substantially of particles larger than about 30 mesh size; controlling the temperature during the contacting at a level suitable for the sorption of oily constituents in the pores of the contact material and below that which would cause substantial coking of the asphalt constituents, which constituents remain substantially unsorbed in the pores of said contact material; eflecting separation of the contact material bearing sorbed oily constituents from the unsorbed constituents of said hydrocarbon feed stock; passing the separated contact material bearing sorbed oily constituents downwardly as a substantially compact column through an elongated, confined substantially vertical conversion zone to eflect conversion of said oily constituents to lower boiling gaseous products; passing a hot liquid heat exchange medium downwardly through said column at a rate below that which would flood the voids in said column, said heat exchange medium being incapable of substantially wetting said contact material, controlling the supply rate and temperature of said liquid heat exchange medium to effect heating of said contact material to a temperure suitable for said hydrocarbon conversion, separating the gaseous products from said contact material and liquid heat exchange fluid, separating the used contact material upon which a carbonaceous deposit has formed from the liquid heat exchange fluid, passing the used contactmaterial through a confined regeneration zone while contacting it with an oxygen containing gas to burn oil said carbonaceous contaminants, passing a second fluid heat exchange medium in heat exchange relationship with said contact material in said regeneration zone to remove the heat liberated by said contaminant burning, efiecting an exchange of heat from said'second heat exchange medium to said first heat exchange medium which has been separated from said used contact material, thereby heating said first heat exchange medium to a temperature substantially above the average conversion temperature in said conversion zone, returning said first heat exchange medium to 8. A process for conversion oi high boiling oily constituents in asphalt bearing hydrocarbon fractions to lower boiling products which comprises: contacting said liquid fraction with a porous particle form inorganic oxide gel-type catalyst in which most of the pores are micropores and the volume of pores having radii larger than about 100 Angstrom units is less than about 30 percent and in which the particles are greater than about .022 inch average diameter to effect sorption of the oily constituents of said fraction in the pores of said catalyst while leaving the asphalt constituents substantially unsorbed, eflfecting separation of said catalyst bearing sorbed oily constituents from the non-sorbed asphalt constituents, passing said catalyst bearing sorbed oily constituents downwardly through a confined conversion zone as a substantially compact column, introducing a molten metal heat exchange medium into the upper section of said conversion zone at a temperature substantially above the desired average hydrocarbon conversion temperature, percolating saidheat exchange medium downwardly through said column at a rate sufficient to heat it to a temperature suitable for conversion of said oily constituents to lower boiling gaseous products, and withdrawing the gaseous products, used catalyst and heat exchange medium from the lower section of said conversion zone.

7. A process for conversion of high boiling oily constituents in asphalt bearing hydrocarbon fractions to lower boiling products which comprises: contacting said liquid fraction with a porous particle form inorganic oxide gel-type catalyst in which most of the pores are micropores and the volume of pores having radii larger than about 100 Angstrom units is less than obout 30 percent and in which the particles are greater than about .022 inch average diameter to effect sorption of the oily constituents of said fraction in the pores of said catalyst while leaving the asphalt constituents substantially unsorbed, effectin separation of said catalyst bearing sorbed oily constituents from the non-sorbed asphalt constituents, passing said catalyst bearing sorbed oily constituents downwardly through a confined conversion zone as a substantially compact column, passing a hot liquid heat exchange medium downwardly through said column at a rate insuflicient to flood the voids in said column but at a temperature and rate sufficient to heat said catalyst to a temperature suitable for conversion of said oily constituents to lower boiling gaseous products, said heat exchange fluid being incapable of substantially wetting said catalyst, withdrawing the used catalyst, gaseous products and liquid heat exchange medium from the lower section of said 20 conversion zone, separating said gaseous products from the catalyst and liquid heat exchange medium, draining the liquid heat exchange medium from said catalyst and finally purging said catalyst with a suitable inert purge gas, passing the purged catalyst through a confined regeneration zone while contacting it with an oxygen containing gas to burn off from the catalyst carbonaceous contaminants deposited thereon in said conversion zone, cooling the regenerated catalyst to a temperature suitable for its use in sorbing oily constituents and re-using the cooled catalyst for above the average hydrocarbon conversion temperature in said conversion zone and returning the heated heat exchange medium to the upper section of said conversion zone.

8. A process for conversion of oily constituents in asphalt bearing hydrocarbon liquid feeds which comprises: contacting the hydrocarbon feed with a porous, particle form solid sorbent in which most of the pores are micropores and the volume of pores having radii larger than about Angstrom units is less than 30 percent of the total pore volume and having an average particle diameter greater than that corresponding to about 60 mesh Tyler, controlling the contact time and temperature and the relative amounts of liquid and sorbent contacted to eflect sorption of the oily constituents into the pores of said sorbent while leaving substantially unsorbed the asphalt constituents, separating the sorbent bearing sorbed oily constituents from the unsorbed asphalt constituents, and passing a hot preheated molten metal directly into contact with said contact material to heat it to a temperature suitable for the desired conversion of said sorbed oily constituents.

LOUIS P. EVANS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'ENTS Number Name Date 226,001 Reibeck Mar. 30, 1880 1,278,023 Rosenbaum Sept. 3, 1918 1,447,297 Day Mar. 6, 1923 1,568,018 Forrest et al Dec. 29, 1925 2,354,354 Abrams July 25, 1944 2,354,355 Abrams et a1 July 25, 1944 2,382,755 Tyson Aug. 14, 1945 2,437,222 Crowley, Jr., et al. Mar. 3, 1948 OTHER REFERENCES Allibone: Journal of the Institute of Petroleum," vol. 2'7, pages 94-108 (1941).