US1798341A - Treating petroleum oils - Google Patents

Description

March 31, 1931. P. M. TRAVIS TREATING PETROLEUM OILS Filed July 15, 1927 Sheets-Sheet 1 INVENTOR Pierce/114.5017 Fans BY A ' ATTORNEY5 March 31, 1931. P. M. TRAVIS v TREATING PETROLEUM OILS Filed July 13, 1927 Z $h65t$-5h68t 2 5 5 Wm mm m m A M Q \Q w flw MW. 3 Q N Wm Patented Mar. 31, 1931 UNITED STATES PATENT OFFICE PTERCE MASON TRAVIS, OF RIDGEWOOD, NEW JERSEY, ASSIGNOR T TRAVIS PROCESS CQRPORATION, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF DELAWARE TREATING PETROLEUM OILS This invention relates to improvements in the treatment of petroleum oils and residues for the removal of suspended solid and semisolid materials therefrom and to obtain a clear liquid free from substantial sedimentation. The invention is of particular value and application in the treatment of residual oils from commercial cracking operations, for example, pressure cracking operations conducted for the production of motor fuels from heavier hydrocarbon oils.

Residual oils obtained from cracking operations of this character contain relatively large quantities of free carbon, a byproduct of the cracking reaction, which is present in different sized particles, varying from coarse granules, which settle readily, down to particles of a few microns diameterwhich are dispersed throu h the liquid oil in a semi-colloidal state so t at their removal by settling is difficult even on prolonged standing. In addition to free carbon residual oils from the usual commercial cracking operations contain tarry, carbonaceous substances which tend to slowly settle out with the free carbon forming a gummy mass which makes oils containing constituents of this character unsuitable for fuel because of the pronounced tendency to foul the fuel lines, burners and regu-.,

lating valves, making continuous and well regulated firing extremely diflicult. Appreciable sedimentation on standing is also objectionable in oils to be used as bunker fuels because of the difiiculty due toinaccessibility of removing sediment which accumulates in ship bunkers. Further, the presence of these tarry or pitch-like constituents makes separation of the free carbon from the oil by the ordinary filtering operations impossible from a practical standpoint due to rapid plugging and tarry materials may be removed from oils containing them in suspension, which gives a maximum yield of clarified 011. The proccentrifugal action in a revolving cylindrical container. Solid carbon and tarry matter which are heavier than clear oil are separated by the action of centrifugal force, which is many times the force of gravity, forming a' separate layer at a greater distance from the axis of rotation than the clarified oil. The solid material forming the outer layer is caused to move arallel to the axis of rotation by positive mec anical forcing means and is discharged continuously in the same manner with motion inwardly toward the axis of rotation. Fresh oil is fed continuously to the interior of the revolving cylinder, moving along the periphery of the cylinder parallel to the axis of rotation in a direction opposite to the movement-of the solid material and is similarly discharged continuously with movement toward the axis of rotation. In traveling along the periphery of the revolving cyl inder the liquid oil is subjected to centrifugal pressure for an appreciable period of time so that a thorough separation of the solid and semisolid materials from the liquid oil is effected. The solid materials are discharged at a point nearer the axis of rotation than the point at which the clarified liquid is discharged and is thereby separated from oil remaining admixed therewith so that the former are discharged in a substantially dry condition thereby obtaining a maximum yield of clarified oil. I

The invention will be further described in connection with the accompanying drawings which illustratein a somewhat conventional manner one form of apparatus adapted for the practice of the improved process of the invention, but it is intended and will be understood that this further description is for the purpose of exemplification and that the invention is not limited thereto.

In the drawings: Fig. 1 is a somewhat diagrammatic representation in elevation of an arrangement of apparatus adapted for the practice of the improved process of the invention.

Fig. 2 is an elevation partly in section of one form of centrifuge suitable for use in the arrangement illustrated in Fig. 1.

Fig. 1 of the drawings shows a storage tank 1, provided with a heating coil 2 and connected through with the centri uge 7. The standpipe 8 is interposed in the feed line to assist in maintaining a constant feed to the centrifuge 7. Tank 1 is shown equipped with a stirring device 9 so that the body of oil therein may be agitated to prevent settling to the extent that the feed line might become choked. The clarified oil is discharged from the centrifuge through pipe 10 and the solid material is discharged through connection 11 to the conveyor 12.

The centrifuge illustrated in Fig. 2 comprises a bowl 13 supported by the supporting web 14 and rotatably mounted on shaft 15. The element 16 is keyed to the shaft 15 and is provided on its outer surface with extension 17 which is helical in form and extends approximately to the interior of bowl 13. The central portion of the bowl 13 is cylindrical in form, tapering toward the shaft at one end. The other end of the bowl is provided with a ring 18 extending inwardly from the periphery of the bowl. The tapered end of the bowl is continued until it approaches nearer to the shaft 15 than the inner edge of the ring 18. The bowl 13 is provided with a series of openings 19 around its periphery at one end beyond the ring 18. The shaft 15 extends through the gear casing 20 and may be driven directly from any suitable source of power, for example, by a silent chain engaging the sprocket 21. The bowl 13 and supporting web 14 are driven by the collar 22 from the shaft 15 through a set of diiferentia 'gears in the gear casing 20 so that the bowl 13 rotates in the same direction as the helix 17, but at a slightly lower speed. While both the bowl 13 and the helix 17 rotate at high speed the differential be-' tween them is relatively small so that any difficulties incident to the provision and care of a high speed bearing between the shaft 15 and the collar 22 are eliminated. The direction and speed of rotation of the helix 17 relative to that of the bowl 13 is such that the helix will operate to discharge continuously at the tapered end any sol1d material which would ot erwise accumulate within the bowl, for example, the bowl may be driven at 800 to 900 R. P. M. and the helix at 850 to 950 R. P. M. Collecting rings 23 and 24 are provided at opposite ends of the bowl to collect the clarified oil and separated solid material as they are discharged from the pipes 3, 4 and 5 and pump 6 bowl. The shaft 15 is provided with a stuffing box 25 to prevent leakage of the material introduced through the hollow shaft.

In the operation of the apparatus described and illustrated in accordance with the improved process of the invention the oil to be treated is heated preferably to a temperature of between 120 and 135 F. by circulating steam or other suitable heating mediums through the heating coil 2. This range of temperature has'been found to give particularly advantageous results though a somewhat higher temperature may to advantage be employed in treating an exceptionally heavy oil to reduce its viscosity and perm1t greater ease in handling. The heated oil is supplied to the stand pipe 8 by the pump 6 from which it is constantly fed to the interior of the bowl 13, assing through the shaft 15 and a series of openings26 in the element 16. The centrifugal force causes the solid materials suspended in the oil to separate and form an outer layer which is me chanically conveyed to the tapered end of the bowl by the helix 17 where it is discharged continuously. The speed of the helix 17 relative to the bowl 13 is not sufiicient to act positively on the liquid which passes in the opposite direction overflowing at the inner edge of the ring 18 as it is displaced by fresh oil supplied to the bowl. The time during which the oil is subjected to centrifugal action may be regulated by the rate at which fresh oil is supplied and by the length of bowl employed. The speed at which the bowl is driven will vary somewhat with the nature of the oil being treated, the degree of dispersion of the solid material therethrough and the maximum amount of sediment permissible in the clarified oil. A bowl 24" in diameter revolving at 800 R.- P. M. will usuallybe sufficient to reduce the amount of sediment in residual oils from pressure cracking operations containin initially in excess of 4% solid materials to less than 2%.

If desired the oil may be subjected to a concentrating treatment, for example, a preliminary settling operation and the concentrated solid material centrifugally separated from the liquid oil as above described. Oils containing in excess of 32% of heavy carbonaceous material have been successfully treated in this manner.

When a larger percentage of sediment is permissible in the clarified oil, for example, 5%, a lower speed may be employed or the throughput-increased without decreasing the rotative speed, or a shorter bowl may be employed. Thus, in one instance a residual oil containing approximately 5% of solid carbonaceous material was heated to a temperature of 122 F. and treated centrifugally as above described usin a bowl 24" in dlameter approximately 15" Tong rotating at a speed of 700 R. P. M. The heated oil was supplied to the centrifuging operation at a rate of about 4000 gala, er hour. By this treatment the sediment in t e clarified oil was reduced to 44%. About h. p, was required to drive i the centrifuge in operating at this capacity.

The process of the invention is continuous and eliminates the necessity of the large stora e capacity required where settling 1s relief upon for the clarification of oils of the character above referred to. Other adi vantages are that the apparatus re uired is rugged and does not require critica adjustment nor the supervision of a skilled operator.

1 I claim:

1. The improvement in the treatment of petroleum oil residues for the removal of solid and semisolid materials therefrom, comprising heating the residual oil to be treated to a tem rature of between 120 F. and 135 F. an subjecting the oil while at this temperature to centrifugal force in a separating zone whereby the solid material and clear liquid are separated into layers,

positively conveying the solid material axially in one direction in the separating zone while it is subjected to centrifugal force and causing the liquid to move axially in said zone in the opposite direction, continuously discharging the solid material from the said separating zone at one point with movement toward the axis of rotation and continuously discharging clarified oil from said separating zone with movement toward the axis of rotation at another point.

2. The improvement in the treatment of petroleum 011 residues for the removal of solid and semi-solid materials therefrom, comprising heating the residual oil to be 40 treated to a temperature of between 120 F. and 135 F. and subjecting the oil while at this temperature to centrifugal force, whereby the solid material and clear 1i uid are separated into layers, positively disc arging the solid material in a continuous manner from the zone in which it is subjected to centrifugal force at one point with movement toward the axis of rotation and continuousl discharging clarified oil from said zone with movement toward the axis of rotation at another oint.

In testlmon whereof I aflix m signature. P ROE MASON AVIS.

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