US1636520A - Method of and apparatus for treating petroleum - Google Patents

Description

-/ 1636 52o Juy w 1927 J. w. I Ewls, .JR

METHOD OF AND APPARATUS FOR TREATING PETROLEUM Sheets-Sheet 1 Filed April 4, 1925 INVENTOR. BY M i. @la TTORNEY.

E 9 1927. Ju y J. w. LEWIS, JR

METHOD OF AND APPARATUS FOR TREATING PETROLEUM M4 i* l ATTORNEY.

July 19, 1927.

J. W. LEWIS, JR

METHOD OF AND APPARATUS FOR TREATING PETROLEUM Filed April 4, 1925 4 Sheets-Sheet 4 mwN mvkb ok. -ll 1| l L... .N5 m Ill J .wh .IL NM ATTORNEY.

Patented July 19, 1927.

iran sr-'ATES PATENT OFFICE.

.IosnPH vv. LEWIS, .'m., or PHILADELPHIA, PENNSYLVANIA, AssIeNon yro THE Ar- LAN'rIo EEFINING comPANY, or PHILADELPHIA, PENNSYLVANIA, A coEPonA- 'rien dr PENNSYLVANIA. i

METHOD F AND APPARATUS FOR TREAT'ING ZPETROLEUM.

Application led April 4, 1925. Serial No. 20,638.-

My invention relates to a method-of and apparatus for converting hydrocarbons or mineral oils into lighter oils or oils of lower boiling points and more particularly my invention relates to a method of and apparatus for subjecting petroleum, petroleum. .dis-

tillate or petroleum residuum to conditions of temperature sure to eiiect and super-atmospheric presdestructive distillation, dissociation or cracking ot the oil for the production of light hydrocarbons such as napthas, gasolines and burning or'kerosene oil.

This application is in part a continuation of my prior application Serialv No. 601,220, tiled November 16, 1922.

ln the well-known andl commonly used cracking processes one of the principal sources ot' trouble is in the deposition and accumulation of carbon and carbonaceous matter on the heating surfaces thereby cutting d own the rate ofiheat transfer and, if permitted to continue, eventually rendering the apparatus inoperative.

ln accordance With my invention, the velocity of the oil over the heating surfaces 1s high thereby increasing the rate et heat transfer to the oil and also largely preventing the deposition of any carbon or carbonaceous matter which may be formed. My method is accordingly characterized by high rate of heat transfer into the oil and by high velocity of the oil'over the heating surface, the oil and conversion products preferably remaining Wholl in the liquid phase. To effect the high y or largely rate of transfer of heat energy into the oil and to prevent local superheating, the oil is caused to flow in a helical or equivalent path Within a tube through Whose wall the heat is transferred into the oil flowing in a stream of reduced cross section, in Contact with the inner surface of qthe tube wall. the passage through the helical or equivalent path serving also to sur and intel-mingle all portions of dthe oil and to bring them into substantially direct heat transfer relation with the inner surface of the tube -Wall and with the helix surfaces.

'lhe helical path also serves by its smaller SSS ection to imparta high velocity tothe Aheating surface and because of additional heat actually conducted into the oil and transferred to it by the helix itself.

' In accordance with my invention, the oil may be heated to .a higher temperature than is normally used and the time of the crackit@ ing reaction in the tubes may be thereby decreased. .When such high temperatures are used, it 1s,l of course, necessary to employ correspondmgly high pressures, particularly outhe lighter or lovier boiling oils *charged 55 or produced, to maintain the oil substantially 1n the liquid phase. It is possible by means of my invention to obtain relatively high conversions from high to louT boiling products in a briei cracking period with the 7@ deposition of very little carbon on the l1eat ing surfaces and with low gas loss.

Further in accordance with my invention' there may be utilized a reaction chamber in which the oil is retained While at cracking temperature and in which the major portion or substantially all of the cracking takes l placev after the oil has been heated in the aforesaid helical or equivalent path, in which the heat transfer is so increased and the time se of heating, therefore, so decreased that the oil may be heated to a higher temperature than is otherwise possible Without any substantial cracking taking place in the tubes. The high velocity of the oil in the tubes at S5 the same time substantially prevents -the deposition on the 'heating surfaces o the small amount of carbon which is Jformed, thereby avoiding necessity of cleaning the tubes except at infrequent intervals,. and so 9G lperniitting longer runs, and, at the saine though it will be understood that oils lighter4 or heavier than gas oil or fuel oil may be treated in accordance with my invention for producing oils of lower boiling points.

For an understanding` of some of the modes of practicing my method and for an illustration of some of the forms my apparat-us may take, reference is to be had to the accompanying drawings, in which:

Fig. l is a vertical sectional View, some parts in elevation, of apparatus embodying my invention.

Fig. 2 is a plan view of structure of the character illustrated in Fig. 1.

Fig. 3 is a longitudinal sectional view, parts in elevation, showing an oil cracking tube and the helix member within the same.

Fig. 4 is a fragmentary View illustrating structure of the cooler or condenser.

Fig. 5 is a flow sheet or chart.

Fig. 6 is a vertical sectional view, some parts in elevation, of a modified form of apparatus. A

Referring to Figs. l-el, F is a furnace or -combustion chamber in which gas, oil or other fuel is burned, a blower B driven by motor M being utilized, if suitable or desirable, for supplying air and inducing draft. The hot gases pass from the furnace F through the ue a into the manifold tunnel or flue A, common to and extending in front of the ends of the several tubular cracking stills or units S, ten in number in the example illustrated in Fig. 2.

Each still structurey comprises enclosing and surrounding brickwork b and interior walls or partitions c, of brickwork or the like, forming lines or hot gas, passages d communicating with eachother at opposite ends of the structure and forming a continuous passage. Hot gases from the tunnel A are delivered into the lowermost flue passage d through the flue e, controllable by the "damper f. The gases'flow -to the right, Fig.

1, through the lowermost flue passage d, thence toward the left to the middle flue passage (l, and thence toward the right through the upper Hue passage d, and thence through Y the Hue passage g, controllable by the damper h, to the manifold discharge iue C, controllable by the damper z', to the chimney or stack D.

Extending through each of the flue passages d is a cracking tube T, there being preferably a single tube T for each flue passage d, though it will be understood that two or more tub'es T may be employed in each flue passage. While the tubes T are shownl as disposed horizontally, it will ybe understood that they may be disposed vertically or in any suitable inclined position. Each of the tubes T terminates in the end chambers .7' and 7c, isolated by the endy walls b, b .from communication 4with the flue passages d. Threaded on each end o f each tube T is a coupling flange m abutting against similar flanges n on the pipe members or bends 0, bolts p serving to draw the flanges m and n snugly together to bearing thereon at the periphery of the threads or helical ribs, the core r being provided at either or both ends, as at s, with a squared end for reception of a Wrench or the like for rotating the helix structure H when the apparatus is not in operation for loosening such small deposits of coke, carbon or carbonaceous material as may adhere to the inner wall of the tube T. By uncoupling the pipe sections 0 from a tube T, the helix structure may be withdrawn from the .tubei T, cleaned and reintroduced, or a clean spare helix I-I may be immediately introduced.

In a receivinv or pump house E is disposed a pump of any suitable type, to which the oil to be converted or treated is delivered through the pipe t,`raised in pressure, and delivered to the manifold u, with which communicate the oil supply pipes fv, one for each still unit, a meter w and a valve being disposed in each of the pipes o.

Each pipe 'v delivers the oil, under pressure corresponding with the pressure utilized within the tubes T, to the heat exchange structure G, of any suitable character. In

the example illustrated, it comprises a tube for example, to 550 degrees F., and disy charged from the heat exchange apparatus through the valve a1 to the pipe b1, which connects with the inlet end of the tube system at the left end of the lower tube T, Fig. 1. The oil, after traversing the tubes T. is delivered from the tube'g/ through the valve c1 to the manually adjustable pressure-regulating or automatic pressure-reducing valve V, Which delivers the oil to the pipe (l1 and thence to the coil or worm I of acooler or` condenser J through which cooling medium, as water, is circulated, the saine entering, for example, at e1 and discharging at f1.

The coil or worm I comprises lengths of tube or piping extending through the wall of the box or tank J and connected in series annealed drawn seamless steel tubing having with each other on the exterior thereof by the return bends or couplings g1, Flg. 4, which are removable, so that froml the exterior of the cooler or condenser the interior of the tubes may be accessible for cleaning therefrom carbonaceous or other deposits.

The several worms or pipe coils I of the dierent still units may be disposed within one and the same box or tank J, as indicated lin Fig. 2. The discharge outlet of each,

worm or coil l'is connected through a pipe h1 and a. strainer l with a receiving drum or tank R, in which the-permanent or uncondensable gas and liquid oil separate from each other, the gas being drawn od through the the valve y and pipe k1 to the gas mani- 'old pipe K, which delivers into any suitable gas storage tank. When `the cooler or condenser coil or worm I and drum R are. under super-atmospheric pressure, there may be employed the pressure-reducing valve N, which delivers the gas to the pipe c'l at at* inospheric or slightly super-atmospheric pressure. Connecting with each pipe k1 may be provided a pipe m1, controlled by a valve nl, for Venting the pipe k1 to atmosphere.

i The oil is discharged from the receiver or drum R through a meter o1 anda liquid-delivering trap or valve structure p1, which delivers the oil at lower pressure, if superatmospherie pressure exists upon the drum R, through the pipe g1, controlled by valve '111, to the manifold pipe L, which delivers to storage tank O, or any other suitable destination, 'as for example, the tire stills Lhereinafter referred to in connection with Fig. 5. The meter o1 and trap p1 may be lay-passed through the valve s1, a valve t1 iuteri-'ening between the trap p1 and the bynass..

' Extending across the several stills or pressure tube units is a platform or walk Q, for convenience of the attendants.

'Running adjacent the Walk Q is a pipe U, communicating with a steam boiler for deliveringsteam for purposes of cleaning the pressure tube structure. Connection is made to the pipe U for each tube unit through a valve u1 and a check valve 211 With the pipe b1, whereby steam may be passed through the pipe 111 and through the tubes "l" for blowing them out or cleaning them either before or after removal of the helix structures H, the check valve v1 preventing iiow of vapors or oil to the steam pipe U when the pressure employed upon the tubes T during their operation is greater than that of the steam supplied to the pipe U.

The aforesaid cracking tubes T may be of any suitable material to withstand the pressures .and temperatures involved as herein described, and may be, for example. of

about .5 per cent carbon. y

way of example of apparatus which I Withfmy. invention, it may be stated that the internal diameter of each tube T is two inches and its external diameter about 2.37 5 inches, each tube having a length of about twentyt'eet, of which about seventeen and a halt feet are disposed within the heating zone or flue d, Whose cross section may vary from about six inches to about fifteen inches square. The cylindrical core r of the helix struct-ure H is about one inch in diameter and the thickness of the thread about onequarter inch, whereby the cross section of the helical path for the oil is about onehal't inch deep and three-quarters inch wide, the area of the cross section being approximately three-eighths of a square inch, or about one-eighth of the cross section of the tube. The pitch of the helix is about one inch, whereby for each linear foot ofthe tube T the oil niakesv twelve turns around the core 1'. Any suitable number of tubes T in series or tandem may be utilized, '1nd the rate of delivery of the oil to be treated is preferably such that the time required for the oil to traverse the tubes will be of the order of tive to twenty-live minutes, and a period of ten minutes ais found suitable when using three of the above mentioned tubes having a length of about twenty feet with about seventeen and one-half feet within the heating zone. lVith the aforesaid rate ot delivery of oil to betreated into the cracking tubes, there is ell'ected, because o the helical path and its small cross section, velocity sufficient to prevent deposition of substantial quantitiesot carbon or carbonaceous ma terial upon the heating surfaces. However, by utilizing more tubes in series or tandem, thereby increasing the length of the helical path, thel velocity of flow correspondingly higher, when an equal quantity of oil is pumped through in the saine total time of passage, thereby increasing the rate ot' heat transfer. i

The pressure maintained upon the oil While traversinet the cracking tubes may range from about 200 to about 2000 pounds per square inch, and is effected largely or substantially entirely by the pump P.

The hot gases entering the left end of the lowermost flue passage d have a temperature of the order of 2000 degrees F. and at their discharge at the entrance to the flue g have a temperature of the order of 1000 degrees F. The oil entering the system of tubes T will have a temperature of the order of 550 degrecs, and at the discharge end of the tubes T will have a temperature of the order of 1000 degrees j, the temperature of the oil dropping materially in the heat exchange 'havesuccessfully employed in accordance i days duration the carbon produced weighed out structure G in raising the incoming oil to the aforesaid temperature of about 550 degrees F. However, temperatures of the order of 7 50 degrees to 1050 degrees may be part of the path in opposite direction there- When operating under my method as above described, only very small quantities of carbon or carbonaceous materials are formed. In acontinuous run of about four as little as .05per cent of the Weight of the oil discharged from the drum R.

The treated oil obtained by the use of my invention may subsequently be treated in any suitable vor desirable way, such as by fractional distillatiomyielding distillates of r gasoline and naptha, lamp oil and gas oil,

leaving as bottoms fuel oil or heavylubri- -eating stock, as indicated, for example, in

Fig. 5. The various distillates may be chemically or physically treated in any of the well known ways to yield standard products.

'The utilization of the helical path of the type above described is further of advantage in a system of the character indicated-in Fig. 6, wherein the oil is first 'heated for a relatively short period during traverse of the helical path at velocity higher than in the system of Fig. 1 and in liquid phase to raise itl to suitably high temperature, Withsubstantial cracking and then discharged into the reaction chamber Z, preferably heat-insulated, and of suitably large dimensions to retain a large bulk of liquid oil, where the majorportion or substantially all of the cracking is effected during the prolongedperiod during which the oil remains .in that chamber at suitable cracking temperature, the high pressure obtaining in the tubes, or suitably lower super-atmospheric pressure, being maintained in the reaction chamber. A

In this case, the rate of combustion in the furnace F may be suitably higher than in the system of Fig,` l to enhance rapidity of heating the oil in traversing the helical path and preferably also to 'cause itto attain a relativelyV higher temperature vupon discharge from the tubes to the reaction chamber Z.

In theexample indicated in Fig'. 6, the oil to be treated is introduced, either cold or previously heated, under pressure by a suitable pump, corresponding With pump P of Fig. 1, at a2, into the tube system from which it is discharged through the line b2 to the reaction chamber Z.

The'oil remains for a substantial period in the react-ion chamber Z, for example, twenty minutes, and is discharged through the pressure-reducing valve c2, together with some vapors, into the vaporizing chamber or fractionating tower d2, in which there may obtain substantially atmospheric pressure or preferably a super-atmospheric. pressure, for example, forty pounds per square inch'. From the upper portion of the tower d2 there are drawn off through the line e2 certain vapors, comprising the lighter conversion products and some unconverted oil or comprising lighter conversion products only, and delivered 'to the cooling worm f2 of the Water-cooled condenser g2. densate is then delivered to the receiving drum R-wherein the gas is separated from the condensate, the gas being drawn oli*l through l the line h2 and the condensate .through the line 2, the condensate then being further refined, as by distillation of the' general character indicated in Fig. 5.

In the bottom of the vaporizing or fracf tionating tower d2 is collected the unvaporized portion of the material discharged from thereactionchamber Z. This material is'of the character of tar or fuel oil, which is dischz'izcrged through the worin jg of the tar cooler 2.

In a system of the character described in connection with Fig. 6, the rate of transfer of heat into the charged oil in thetubes T is high, and the period of heating relatively short, with no or at most only small amount of cracking of the oil during traverse ofthe heating tubes. Furthermore, the velocity of the oil through the helical path is sufficiently high to a'ord insuticient time for cracking and to ensure that such small quantities of carbon or carbonaceous material as may be formed are not to substantial degree de- The conlli) posited upon the heating surfaces. l4`urtheiq The foregoing method as described in con- .f

nection with the use of the reaction chamber is preferred, though it'will be understood that other modes of use of reaction chamber may be practiced. For example, a lower pressure may be used upon the tube structure T and Within the reaction chamber, in

Which event vaporization may take place in that chamber., and the 'vapors drawn olf ,therefrom for condensation, and there may 'be drawn off from the reaction chamber tar point from higher boiling point hydrocarbon oils, which comprisespassing the higher boiling point oil in liquid phase-in a helical path through a tubular passage in a stream Whose cross section ,is a small fraction of the cross 'section of said tubular passage, and subjecting the oil While in said helical path to cracking temperature.

2. A tubular pressure cracking still structure comprising a tube, a stationary helix member therein, said helix member having such pitch and having a core of such diameter that the cross section of the helical path is a small fraction of the cross section of said tube, means for forcing oil in liquid phase through said helical path, and heater structure surrounding said tube.

3. In the art of producing lower boiling point from higher boiling point hydrocarbon oils the method which comprises rapidly passing the higher boiling point oil in liquid phase While under super-atmospheric pressure once through a heating zone in a helical path through a tubular passage in a stream Whose cross section is a small fraction of the cross section of said tubular passage, subjecting the oil While in said helical path to cracking temperature, thereafter delivering the hot oil into a cracking zone, and effecting the major portionl of the cracking in said crack-l ing zone.

4. Still structure for cracking hydrocarbon oils comprising a tube, a stationary helix member therein, said helix member having such pitch and having a core of such diameter that the cross section of the helical path is a small fraction of the cross section of said tube, means for forcing the oil in liquid phase under super-atmospheric pressure through said helical path, heating structure surrounding said tube, and a cracking chamber to which the heated oil is delivered from said helical path. l

JOSEPH W. LEWIS, JR.

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