US2248677A - Apparatus for coking petroleum - Google Patents

Description

y 8, 1941. R. WQGARMAN 2,248,677

' I APPARATUS FOR COKING PETROLEUM Filed June 5, 1939 2 Sheets-Sheet 1 12 4o E 3'6 J 7? I J a 2? an 42 27 22 re I /7 /4 l7 4/ 27 I 7 42 ==CI= O I 8 v 3 INVENTOR:

- BY 9 W 54/241444 I Km- ATTORNEY.

July 8, 1941. R. W. GARMAN 2.248577 APPARATUS FOR COKING PETROLEUM Filed June 5, 1939 2 Sheds-Sheet 2 i 29 l I I I I INVENTOI: G 2444/) ATTORNEY.

' Patented July 8, 1941 UNITED STATES PATENT OFFICE APPARATUS FOR come PETROLEUM Reed Waldo Garman, South Pasadena, Calif.

Application June 5,1939, Serial No. 277,438

11 Claims.

It is an object of the invention to provide apparatus for the simplified treatment of heavy petroleums so that a substantially continuous process of converting such heavy oils into lighter oils and coke can be had with minimum shutdown periods for cleaning out coke.

Another object is to provide an improved apparatus for substantially continuous operation in cracking heavy oils to produce lighter oils and coke. 1

The invention will be better understood by ref erence to the drawings, in which:

Fig. 1 is an elevation, partly in section, showing one form of suitable apparatus;

Fig. 2 is a modification of Fig. 1.

Fig. 3 is an interior view along the lines 3-3 of Fig. 1.

Fig. 4 is a side view, partly in section, showing details of construction.

The invention will be described with reference to the use of the apparatus for treating heavy petroleums to produce lighter oils and coke, although it will be understood that the invention is not limited to this specific use.

Heretofore, in the so-called coking stills used in the art for treating heavy oils, the oil has been preheated to above its cracking temperature and discharged into a receptacle, or evaporator, where the cracking temperature is maintained for the production of lighter oils and the inevitable deposition of coke which eventually accumulates as a solid mass so that long and costly removal is necessary for the practically solidified mass.

Petroleum coke has the attribute of adhering strongly to the usual steel stills in refineries and with the heavy petroleums high in sulphur it is,

impossible to remove the coke residues from coking stills except by breaking the solidified coke mass.

Further, inasmuch as the bulk of the. sulphur remains in the coke, high corrosion efiects cause rapid deterioration of such ordinary apparatus and there is consequently a thickness of coke left on the metal which is practically impossible to remove and which serves as a base on successive coking charges whereon the coke quickly reaccumulates.

In other words, in ordinary coking stills, the coke is never formed so as to be easily broken and removed to leave a clean metal surface.

More particularly, in the so-called delayed cokers recently gone into use forcoking heavy oils, it is usual to quickly heat the oil well above its cracking temperature and then quickly discharge the oil into the bottom of a receptacle, or evaporator, wherein'the heat in the oil in excess of the heat finally retained in the residue at coking temperatures is sufiicient to convert the heavy oil to lighter oils and coke, provided there is suflicient time allowed after thus charging the receptacle before the receptacle is opened to remove the coke which forms a single deep mass. Such coke is hard to break and remove, the socalled cable method often being used in which a spirally coiled metal cable is first placed in the empty receptacle around which the coke forms and when the-coking is completed, the ends of the coil are pulled out through an opened manhole thus fracturing the coke which is then manually removed. Coke removal from such delayed cokers is also accomplished by a so-called hydraulic method. v

I have discovered that, by the use of certain flexible, corrosion-resistant alloys, the deposition of a mass of coke thereon is immaterialto its ready fracture and easy removal while carrying on a coking process.

When such alloys are formed and arranged, a plurality of coking stills assure continuous operations when coking the most refractory, high sulphur, heavy petroleums.

In this respect, it'must be remembered that coking stills are used to recover valuable products, such as gasoline, kerosene, gas oil and fuel oil from viscous heavy petroleums, or residuums, which alone is of little value for ordinary cracking operations because its conversion quickly plugs the whole apparatus with coke and which, further, has little adapt..bility for fuel oils due to its viscous nature and high sulphur content. Such heavy oils may run from about eight to fifteen degrees Baum gravity, and ordinarily, as crude oils, contain no gasoline.

Referring to Fig. 1; if such a heavy oil is quickly heated to a degree well above its cracking temperature as, for instance, by passage through the tubes of any well known oil refinery heating apparatus, and is then quickly discharged into coking still IQ of this invention by pipe ll, so that the time during which the oil is being thus heated in such tubes is insufiicient to cause any substantial degree of cracking whereby coke will be deposited in such tubes, the thus heated heavy oil may be then further heated in its downward passage through still H! by indirect heat so as to produce lighter oils and coke in a relatively short time, the coke produced being exceptionally porous, brittle, and easily removable. As there would normally be a large temperature drop in the ordinary delayed cokers, such drop is herein eliminated by continuous indirect heating with hot vapors and the lengthy time of coking is also eliminated.

Coking still l comprises an outer shell I! of steel or iron capable of withstanding a desired superatmospheric pressure which is lined substantially throughout its length with corrosion proof, flexible sheet metal 13 formed into suitable corrugations and welded completely round its upper and lower ends to shell I! to form a space M to which is joined pipe 15; sheet l3 being also spot welded at suitable points throughout its length to shell l2 for proper strength and support.

The form of corrugations in sheet l3 are shown as longitudinal, but any suitable corrugations are effective to cause movement of sheet l3 responsive to a fluid pressure introduced into space H through pipe l5, such as air, steam, or the like.

Sheet I3 is formed of a ductile, flexible, noncorroding alloy having long life under repeated stresses, such as the nickel-copper-iron alloy known as Monel metal, capable of withstanding temperatures as high as 1000 F. or higher without permanent deformation. Other nickel alloys are especially valuable and the alloy commercially known as inconel metal, containing approximately 80% nickel, 14% chromium, and 6% iron, is very useful when processes are used requiring high resistance to oxidation under 2000 F. together with resistance to sulphur, hardness under impact and little fatigue under high temperatures.

These alloys are merely illustrative and the invention comprehends the use of any metal, or alloy, to suit a given condition of use.

Supported within the inflatable sheet l3 are a plurality of cones, or hoppers, IS, a description of one of which applies to all.

Each cone I is formed of a suitable flexible metal or alloy, as described, having radial corrugations terminating in a substantially circumferential line where it is tightly welded to sheet l3, the cone having its lower end controllably free and relatively restricted compared to its welded upper end; said lower end being regulably expanded as desired.

At spaced intervals on the under side of cone iii are lightly welded narrow metal strips l1 which are preferably set in a corrugation to give added strength and certain of said strips form a stiffer base for connection on the other side of the corrugation to an operating linkage comprising a plurality of arms l8, pivoted at one end to certain stiffened corrugations and at the other end to a collar 19 slidably encircling a central supporting stem 20, moreclearly shown in Fig. 3.

Collar I9 is provided with trunnions 2| journalling the end of a yoke 22 fixed on a shaft 23 adapted to be oscillated exteriorly by lever 24 through a stufling box 25, whereby the smaller end of cone l6 may be expanded and contracted.

Inasmuch as accumulation of coke on any part of the interior of still II] in any quantity is not desired, all operating parts may be made of noncorroding alloys as described, and stem 20 may be further covered between collars I9 with corrugated flexible metal 26 which is cylindrical for a distance suflicient to permit collars l9 to slide. Below each collar IS in each cone I6 is flxed a plug 2'! formed of two oppositely concaved corrugated disks 2B, which may be formed as a welded extension of covering 26 and welded circumferentiaily to supporting plates 29 and 30 having perforations 3| and 32 therein respectively, and the periphery of plug 21 is fashioned to fit loosely into the corrugations in cone l6.

Within a plug 21, stem 20 is perforated at 34 and its lower ends are connected to a pipe 35 for the purpose of applying a fluid pressure to disks 28 as well as to the corrugated covering 26. Stem 20 is suitably supported at the upper and lower ends of still ID by spiders 36 and 37 respectively.

A dump cover 38 is placed at the bottom of still l0 and an inlet pipe 39 serves to introduce a heated gaseous medium while such medium is withdrawn with evolved products through pipe 40.

In the operation of the device for cracking and coking heavy petroleums, the oil heated very quickly to the desired degree, say from 900 F. to 950 F., somewhat above the average coking temperature of 800 F. to 850 F., is introduced into still II) by pipe ll while simultaneously there is introduced a heated fluid medium through pipe 39, it being understood at the start of the operation that the lowermost cone ii is restrictedly open by plug 2'! while the remainder of cones I6 are wide open.

By restrictedly open is meant that there is suflicient space left between the corrugations 33 of plug 21 and the corrugations of cone IE to permit the passage of the heated gaseous medium through the accumulating heavy oil in cone I6, so that a cracking, stripping, and agitating step takes place.

The gas used for such step may be any hydrocarbon gas or vapor heated to a degree where it rapidly transfers its heat to the oil to effect cracking, or conversion, with the production of coke, such as the gases or vapors from the stabilizer of another cracking unit because these are often waste gases and are highly useful in the present process inasmuch as they not only serve as a heating and cracking medium but are believed to enter into the reaction to effect polymerization and be polymerized or condensed with other hydrocarbons in the presence of coke as a catalyst to produce highly valuable lighterprodnets in the gasoline boiling range.

Further, hot hydrocarbon vapors discharged from the cracking tubes or reaction chamber of a so-called vapor phase cracking plant may be directly used because they are already at the desired high temperature for converting the heavy oil and the light gas oil and kerosene in such vapors may undergo further cracking in their passage through-the dried and heated coke while solids carried by such vapors combine with the coke and the so-called fixed gases mixed with the vapors undergo a degree of polymerization in the passage through the dried and heated coke.

Obviously, there is no substantial loss in using such vapors containing fixed'gases and comprising gasoline, kerosene and gas oil fractions.

If the oil is introduced through pipe II at temperatures between about 750 F. and 950 F., with a tendency for very sudden temperature decrease to as low as 700 F., due to the latent heat passer? and the endothermic cracking reaction, the gas will be introduced through pipe 39 at temperatures between about 900 F. and 1000 F., suflicient to cause the desired cracking and coking.

The down-flowing heated oil is subjected to contact with the rising heated gas, or vapor, and in the lowermost cone I 6 the conversion to light oil in vapor form and to coke continues as oil is deposited on. such lowermost cone I6 until a predetermined depth of reduced oil and coke is reached at which time the next succeeding upper cone i6 is closed to the restrictedly open position while the lowermost cone remains in its restrictedly open position. Then the continually rising heated gas in its passage through the reduced liquid and coke on the lowermost cone It continues until such reduced liquid is completely converted to lighter oil vapors and coke. Contrary to expectations, it has been found that such coke accumulation, while relatively solid, is quite porous and permits the continuous passage of heated gas therethrough to agitate and convert the liquid stream continually being deposited on any upper cone Ill.

Inasmuch as-the rising heated gas passes very readily through the coke accumulation and inasmuch as such coke can be more easily removed from the various cones it when it is as thoroughly dried as possible by the continually rising heated gas, none of the cones IE will be opened until the supply of heated gas through pipe 39 is discontinued whichwill occur when a desired level has finally accumulated in the uppermost cone l6.

Such level in each cone i6 is best as a point where the expansibility of the corrugations in cone it is suflicient to free the coke which thereupon fractures into easily dumpable small particles.

In like manner, each cone i6 is utilized up to a certain level of accumulated coke until the uppermost cone is thus used, whereupon the liquid and gaseous streams may be diverted to a second similar still while the gaseous stream continues through the still i and then on through a second similar still until dry coke is formed on the uppermost cone of still I, after which the gaseous stream may be completely diverted to the second still, thus making the operation substantially continuous.

Manhole 38 may then be opened and'pressure applied, alternately, positive and negative, through pipes 18 and 35 alternately to expand and contract all expansible surfaces and thereby loosen coke from such surfaces, leaving the interior ofstill 10 in substantially clean and noncorroded condition for a fresh run.

Lowermost cone i5 may then be opened to expand such cone and dumpthe coke fractured by such action and any coke from the expansible surfaces into the bottom of still l8 and out through manhole 38. This lowest cone is may be subsequently opened and closed several times to thoroughly clean the surfaces and then left in a wide open position while each succeeding upper cone is operated in a similar manner, and so on until all the cones are dumped, each cone in the rising series being left wide open as it is cleaned. Manhole this then closed and the lowest cone is is closed to a restrictedly open position and still i0 is ready for a second run when the second still in the series becomes charged with coke. Any number of such stills as are desired or necessary may be used in series with the usual pipe connectionaor cross-overs, for continuous operation.

Cone I6 should have considerable conical slant when closed, about 40 from horizontal is found suitable, so that a relatively small angular change '(say, to about 60) will make a relatively great enlargement of the lower diameter and the cor rugations 33 of plug 21 should only give suiiicient clearance to permit free passage of gas while preventing slippage of any liquid oil.

With these controls, the coke is substantially dry,'which makes it more readily removable than wet coke and to this end the temperature of the dried coke should preferably be less than 1000 F. because it is much more brittle and fracturable by the apparatus than when above 1000 F.

In the modification in Fig. 2, similar instrumentalities are utilized and operated by metal bellows di connected by pipes 42 to a source of fluid under pressure which are thus operated without great manual efforts The operation may be-operated under superatmospheric pressure of any desired degree but can be operated at atmospheric pressures, preferably between atmospere and pounds per square inch.

I claim as my invention: v

1. Appa'ratus'for recovering solids from liquids comprising: a tower containing a flexible contact cone, means to supply liquid to an upper part of said tower to flow downwardly into said cone, means to supply a gas to a lower part of said tower, means to withdraw said gas from an upper part of said tower after passage through said cone, and. means to flex said cone.

'2. Apparatus for recovering solids from liquids comprising: a tower containing interiorly a series of superimposed contact cones, means to supply liquid to an upper part of said tower to flow downwardly into said cones, means to supply a gasto a lower part of said'tower, means to withdraw said gas from an upper part of said tower after passage through said cones, and ex-' terior means to independently flex said cones.

3. Apparatus for recoveringsolids from liquids comprising: a tower containing'a flexible contact cone, means to supply liquid to an upper part of said tower to flow downwardly into said cone, means to supply a gas to a lower part of said tower, means to withdraw said gas from an upper part of said tower after passage through said cone, means to retain said liquid in said cone, and means to flex said cone.

4. A tower comprising a shell having an inlet for liquid at an upper part, an inlet for gas at a lower part, an outlet for gas at an upper part, a flexible frusto-conical contacter fixed interiorly of said shell to receive said liquid and gas in direct countercurrent flow and adapted to discharge its solid contents downwardly, means to maintain liquid in said'contacter, and means to discharge the contents of said contacter.

I 5. A tower comprising a shell having an inlet for liquid at an upper part thereof, an inlet for gas at a lower part thereof, an outlet for gas at an upper part thereof, a corrugated frusto-conical contacter fixed interlorly of said shell intermediate said liquid and gas inlets and having its smallest cross-sectional area discharging downwardly, means to maintain liquid in said contacter, and means to flex said contacter.

6. A tower comprising a shell having an inlet.

for liquid at an upper part thereof, an inlet for gas at a lower part thereof, an outlet for gas at an upper part thereof, a corrugated frustoconical contacter fixed interiorly of said shell intermediate said liquid and gas inlets and having its smallest cross-sectional area discharging downwardly, means to maintain liquid in said contactor, means to flex said contacter, a. plug in said smallest area adapted to retain material in said contacter, and means to expand said contacter about said plug to discharge said material downwardly.

7. A tower comprising a shell having an inlet for liquid at an upper part thereof, an inlet for gas at a lower part thereof, an outlet for gas at an upper part thereof, a corrugated frusto-conical contacter fixed interiorly of said shell intermediate said liquid and gas inlets and having its smallest cross-sectional area discharging downwardly, means to maintain liquid in said contacter, means to fiex said contacter, a corrugated plug in said smallest area adapted to retain material in said contacter, and means to expand said contacter about said plug to discharge said material downwardly.

8. A tower comprising a. shell having an inlet for liquid at an upper part thereof, an inlet for gas at a lower part thereof, an outlet for gas at an upper part thereof, a series of spaced corrugated frusto-conical contacters fixed interiorly of said shell intermediate said liquid and gas inlets and adapted to discharge their contents downwardly from the uppermost contacters to the lowest contacter, means to maintain liquid in each contacter, and means to independently fiex each contacter.

9. A tower comprising a vertical shell lined substantially throughout its height with a flexible metal covering, a central shaft in said shell, a series of frusto-conical flexible metallic contacters fixed at spaced intervals on the inner wall of said shell at their large circumference, a series of plugs fixed on said shaft at intervals so spaced as to place each one of said plugs at about the interior of the small circumference of each of said contacters to partially ,close the discharge of each of said contacters means to flex said metal covering, and means to expand each contacter independently about each plug. 10. A tower comprising a vertical shell lined substantially throughout its height with a flexible metal covering, a hollow central shaft in said shell having a flexible metal covering, a series of frusto-conical flexible metallic contacters fixed at spaced intervals on the inner wall of said shell at their large circumference, a series of plugs fixed on said shaft at intervals so spaced as to place each one of said plugs at about the interior of the small circumference of each of said contacters to partially close the discharge of each of said contacters, independent means to flex said metal coverings, and means to expand each contacter independently about each plug.

11. In a tower having an inlet for liquid at an upper portion thereof, an inlet for gas at a lower portion thereof, and an outlet for gas at an upper portion. thereof; a radially corrugated frusto-conical metal contacter having a larger circumference fixed to the interior of said tower with its smaller circumference at a lower level than said larger circumference and being positioned between said inlets for liquid and gas, and means to radially expand said contacter.

REED WALDO GARMAN.

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