US1676826A - Process of treating oils - Google Patents

Description

July 10, 1928.

F. A. HOWARD PROCESS OF TREATING QILS Filed May 18. 1921' Patented July 10, 1928.

UNITED STATES PATENT. OFFICE.-

' FRANK A. HOWARD, OF ELIZABETH, JERSEY, ASSIGNOR TO STANDARD OIL DE- VELOPMENT COMPANY, A CORPORATOIN OF DELAWARE.

PROCESS OF TREATING OILS.

Application filed May 18,

v This invention relates to a process of treating hydrocarbon oils and more particularly to a process wherein heavier tconstituents of said oils are converted by heat 5 treatment into low boiling products and any low boiling products or constituents naturally contained in the said oils are simultaneously removed therefrom. It is illustrated by the accompanying drawing, in which the figure shows a diagrammatic view of apparatus suitable for carrying the'process into effect.

The oils used may be of any desired char acter, a characteristic of the present process being that it is adapted to handle a very wide variety of stocks, including many of types not hitherto readily subjected tohe'at conversion treatments by known methods owing to the heavy deposits of coke "which they/leave in the apparatus. The present process may be carried out, for example, on heavy asphaltic oils such as Mexican crude petroleum of say 0.966 to 0.996 specific gravity and containing low proportions of low boiling constituents, such as oil having, for example, 5 to 10% of natural gasoline and kerosene.

Cold fresh stock is fed from any suitable reservoir 5 through pump 6 and meter 7 to heat exchanger 8, in which it receives an initial preheating. From heat exchanger 8 it passes through pipe 9 and coil 10 in the second .heat exchanger 11 and into the chamber or drum 12, where the stock is derived of its natural naphtha, a process own as skimming. From this drum or still the vapors evolved from the oil pass through vapor line 13 to condenser 14, from which condensates pass through sight-b02115 to receptacle 16.

From the drum or still 12 the skimmed oil or residues pass out through pipe 17 and are forced by pump 18 throu h pipe 19 to a fired coil-20. In practice it y as been found feasible to use about 4" pipes for this coil, and the aggregate length may be about 1600 feet, although either dimension maybe very widely varied. The speed with which the. residue is fed by pump 18 is adjusted. to the firing rate so that the oil emerging from the coil 20 has a temperature between 750 and 900 F., say about 800 and the velocity. in the coil is made sufliciently high that there is substantially no coke deposited in the coil. A feed rate 2,000gallons per hour has 1921. Serial No. 470,565.

been successfully employed. The velocity -of the oil in the coil may be modified in diflerent ways without lowering the temperature of the outgoing oil. The obvious method is to increase the firing rate and the feed rate simultaneously so as to increase the velocity without lowering the outgoing temperature. In any-given apparatus this exped ent may be sufficient to prevent coke deposition. 'It may be found, however, that with the maximum firing possible in the apparatus it is impossible to obtain sufiicient veloc ty to prevent coke deposit without in creasing-the feed rate to a point sufficient to lower the outgoing temperature of the oil below that desired. In that case the velocity may be increased by injecting steam or other gaseous fluid into the oil stream, as by the valve 21 which is provided for that purpose. The steam, spreading through the oil body in the form of bubbles, greatly increases the volume and therefore greatly increases the velocity without absorbing any proportionate amount of heat in transit.

Thus the actual oil velocity through the coil 20 can be raised to any desired extent by steam or gas injection whenever it is found that the limitations of the particular apparatus chosen prevent increase in veloclty without loss of outgoing temperature. Avoidance of coke in coil 20 is principally due tovthe fact that while the oil is raised to a temperature ordinarily considered to be an efiective cracking temperature, it remains in the coil for so brief a period that only incipient cracking occurs, and the oil leaves the coil substantially unchanged, a drop in viscosit and a small decrease in specific gravity using the only effects pro-, duced therein. 95

From coil 20 the oil enters drum 22, which is mounted in a setting '23 in such manner as to receive the flue gases from the setting for the coil 20. In this drum the velocity of the oil is greatly reduced and its size is 100 such that the oil remains in it for a con- 'siderable eriod, in practice, about 1% hours. Copious eposits of coke may occur in this drunrj For this reason only suflicient heat issupplied to prevent great loss in tempera- 105 ture, this being effected, as illustrated, by using the waste gases from the furnace heating thecoils 20. This relatively small'heating is insutficientto endanger thewalls of the drum in spite of the copious coke deposits. 11o

' into'the pressure system in the liquid phase until modified by heat conversion. In the case described, this pressure may suitably be 150 pounds per square inch or higher. The treated oil, after passing through'pressure control valve 26, enters the drum or container 27 above the horizontal baflie 28. By reason of the reduction in pressure upon the liquid, there 'is a considerable evolution of vapors in drum 27 in addition to the vapori zed materials carried through the pressure system." These vapors pass out through pipe 29 into coil 30 in the drum or heat exchanger 8. This coil may suitably be provided at an intermediate point with a trap 31, from which liquid products condensed at that qint are drawn off through pipe 32 to cooling worm 33, from which they pass through sight-box 34, to receptacle 35. Vapors conconverted oil, which enter tinue through the coil 30 to condenser 36, from which condensate passes through sightbox 37, to receptacle 38.

The crude oil or initial stock, in passing throu h the heat exchanger 8, is initially heated by the vapors issuing from the low pressure drum 27 and passing through coil 30. It then passes through the coil 10 in heat exchanger 11 in which it is further heated by the bottoms or residues from the the preheater or heat exchanger 11 through pipe 39 and leave it through pipe 41. The 011 then enters the drum or still 12, in which it is further heated by the products of conversion issuing from the drum 22 through coil 25 under pressure. Here the vapors ofl9 w boiling products are given off from the 0 1 passing outthrough vapor line 13' to a suitable condenser system, While the residues from the oil areforced by the pump 18 through the pressure system as heteinbefore descr bed. The oil attains a temperature of 450 to 550 F. by the time it leaves the drum 12.' All of the natural gasoline and some of the kerosene pass off through the vapor line of the drum 12. The residues, which in the case of an oil of the character above described, will have a specific gravity of 0.993 to 1.014, will be so converted in ,its passage through the pressure system as to produce 20 to 25% or upwards of its own volume of distillate having a specific grgvity of, for example, 0.788 and a residue of reduced viscosity.

through a conduit heated to a temperature such that the oil attains a temperature of 750 to 900 F. while traveling therethrough with a velocity such as to prevent substantial deposition of carbon therein, passing the oil into an enlarged drum, holding the liquid oil in said drum at a temperatureabove 720 F., exerting pressure upon the oil in the conduit and drum to maintain the unchanged charging stock in liquid phase, continuously drawing off the mixed products of conversion from the top of the drum, conveying the products into a chamber in which pressure is released, separately withdrawing the vapors and residues from said chamber, passing crude oil containing low boiling point constituents successivelyinto heat-exchange contact with the vapors from the last mentioned chamber, the residues from said chamber and the converted products issuing from the enlarged drum while passing from the enlarged drum to the chamber in which pressure is released, separately withdrawing the vapors given off from the crude oil and introducing the residue therefrom into the first mentioned heated conduit.

2. The method of treating oils to remove natural low boiling constituents therefrom and effect conversion of high boiling constituents of the residue to low boilingproducts which comprises heating residues to temperatures sufficient to effect conversion of high boiling constituents into low boiling products under pressure sufiicient to maintain unchanged residue in the liquid phase, conveying the mixed products of conversion into a chamber at lower pressure, removing the products therefrom, passing fresh oil containing low boiling constituents into heat exchange relation with the conversion products at lower pressure removed from said chamber, and subsequently into heat exchange relation with the conversion products at higher pressure before they enter said chamber without at anytime permitti'ng admixture of said fresh oil and said conversion products, withdrawing the vapors evolved from said fresh oil and subjecting the residue to the hereinbefore described heat treatment. A

3. The method of treating oils to remove. natural low boiling constituents therefrom and effect conversion of high boiling constituents ofthe residue to low boilin products Which comprises heating resi ues to temperatures sufficient to efiect conversion of highboiling constituents into low boiling products under pressure suflicient to ing the oil into heat exchange relation with 10 maintain unchanged residue in the liquid the mixed conversion products before they phase, conveying the mixed products of conenter the low pressure chamber without at version into a chamber at lower pressure, any time permitting admixture of said fresh separating the vapor and liquid products of oil and said conversion products, Withdrawconversion, passing freshoil containing low ing' the vapo s evolved from the heated 15 boiling constituents into heat exchange relafresh oil and subjecting the residue to the tion with the separated vapor and liquid heat treatment hereinbefore described. conversion products in succession, then pass- FRANK A. HOWARD.

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