US1258191A - Means for cracking hydrocarbons. - Google Patents

Description

J. W.,COAST, Jn.

MEANS FOR CHACKING HYDROCARBONS.

APPLICATION FILED MAR. 22. 1911.

1,258, 1 9 1 Patented Mar. 5, 1918.

M III. I'II Y. I x I] V Il "l IMM-@f UNITEH STATES PATENT OFFICE.

JOHN W. CoAsT, JR., OF TULsA, OKLAHOMA, AssIGNoR To THE PROCESS COMPANY, A

CORPORATION 0F MARYLAND.

MEANS FOR CRACKQING- HYDROCARBONS.

. Specification of Letters Patent.` Patented lIal. 5, 1918.-

Appncationmed Maren 22,1917. yserrant.156,650. l l

To all 'whom it may concern:

Be it known that I, JOHN W'. CoAs'r, J r., a .citizen of the United States ofAmerica, a resident of Tulsa, in the county of Tulsa, State of Oklahoma, have invented certain new and useful Improvements in Means for Cracking Hydrocarbons, of which the following is a full, clear, and exact descrip tion, reference being had to the accompanyingdrawing, forming a part of .this vspecification.

My invention relates to improvements in apparatus for cracking hydrocarbons, and

more particularly `to means for protecting stills from the injurious effects of coke or tarry coke-forming substances.- l y When .high boiling point petroleuln'hydrocarbons are vaporized and cracked in the ordinary cylindrical still, heavy coke-forming substances settle to the bottom of the liquid in the still. If the coke or carbon is .permitted to collect on the still bottom, it

will prevent the free transmission of heat to the liquid contents of the still, and when a suflicient quantity hasaceumulated, the still bottom will become red hot. Some'immediate steps must then be taken to avoid a rupture at the overheated portion of the still. In actual practice, the coke accumu-A lates on the hot still bottom when oil .in the still is maintained at a high temperature and under a high pressure, thus rendering the cracking operation quite dangerous. 0n account of the danger, and for economic reasons,

the coke is usually removed from the still at.

frequent intervals.

Themain object of my invention is to prevent the coke, or tarry coke-forming substances from accumulating on the still bottom where the heat is transmitted to the still. Inthe preferredV form of the invention, this is accomplished by maintaining a body of heavy liquid in the bottom of the i still, floating the oil to be distilled on .said

heavy liquid and transmitting heat through the heavy liquid to vaporize the lioating liquid. The heavy liquid, preferably molten metaL-interposed between the 'still bottom and the oil, prevents the coke-forming substance from reaching the bottom of the still. Since the heat cannot be transmitted readily through the coke or carbon, the latter is preferably circulated or skimmed along the' surface of the heavy liquid to the end portions of the still. By preventing the coke from accumulating on, the still bottom,

the cracking operation may be carried out continuously for` a considerable period of time, without cleaningthe interior of 'the still. Furthermore, the still bottom ,will not be overheated .by the temperature to which it is ordinarily vsubjected.`

Figure I is a diagrammatical view `of a A y cracking apparatus, embodying the features of my lnvention. .i Y q Fig. IIfis a transverse section orl thel still taken on the 'line II-II, Fig. I. y

Fig. III isk a detailv 4viewv of the whereby the vheavyiliquidl',is, displacedy to Contact with a greater area of the still bottom. y f

The still 1, arrangedA above-a heating chamber 2, is connected by means of an air cooled vapor pipe '3 to a reliux condenser/l.l 5 designates a vapor pipe leading fromthe reflux condenser tofa main condensing coil 6 from which the low boiling point'product is recovered.` The condensing coil 6 is preferably arranged in a water tank 7. The air `cooled vapor pipe 3 constitutes a reflux condenser, and it -1s inclined to allow the con- 'densate to liowf backwardly tothe still.

The apparatus I have shown is particularly adapted for use in cracking high boiling point products of distillation, such, for example, l as the distillates or residues resultingfrom the distillation of the crude petroleum. The substances to be treated are V introduced into the still in anyy suitable Y manner, andany desired pressure may beobtained by regulatin a valve 8, preferably located in the vapor pipe 5.v The pressure in the still lis preferably greater than fifty pounds per square inch,'and lthe-temperature vof the contents of the still preferably ranges ,from about 600 F. to 800 \F.

The low boiling point vapors passing from the liquid, flow through the vapor. pipe 3 and reflux condenser 4 to the vpipe 5, leading tothe main 'condenser 6. Therelatively high boiling point fractions are condensed in the vapor pipe 3 or in the condenser 4, such fractions being returned to the still through the inclined vapor pipe 3. This reliux condensate includes a large percentage of heavy coke-forming fractions, commingled `with lighter fractions, which may be redistilled to form In the preferred form of the invention, l

part of the low boiling point product.

the end portions of the still bottom are vseatedupon the walls 9 of the heating chamber, and these walls protect said end portothe bottom of the oil, also float upon theA tionsfrom the intense heat of the heating chamber. The heat is transmitted directly through the middle portion of the still botytom and the protected end portions of the still are maintained in a relatively cool condition. A body of heavy liquid 10, preferably readily fusible metal, for example, molten lead, is maintained in the bottom of the still. The oil to be distilled iioats upon thesurface of themolten lead 10, and the heavy cokeforming `fractions which drop by gravity lead.v The molten lead thus prevents the coke-forming substance from reaching the hot still bottom. The heat i's transmitted from the still bottom, through the molten lead, to the ioating oil. VOwing to the high temperature, the lead is circulated and agitated so as rto very effectively transmit the Y heat to the oil.

The coke is not a good conductor of heat,

Vand it is, therefore, circulated along the surface of the lead to points directly above the walls 9, where'it will not materially interfere` with the transmission of heat from the heating chamber to the oil.

"The means for circulating or skimming the coke comprises a skimmer 11- fitted to a rotary feed screw 12 which extends through a stufling box 13 at one end of the still. Gearing 12 may be operated in any suitable manner to` rotatethe feed screw 12. This I feed screw is reversible, so that it ma be actuated to reciprocate the skimmer 11 rom ,onev end portion of the still to the other.

Stationary rods 14 prevent the skimmer 11 from turningV on the. feed screw 12. The lower portion of the skimmerextends entirely across the lower portion of the still,

landit also extends into the molten lead 10.

By confining the oil and molten lead, as

v herein shown and described, I prevent the vapors generated in the vstilLfrom passing into, or bubbling through the molten lead.

The vapors-are discharged from the upper portion of the still at a point above the oil.

A15 designates a'filling device, in the form of a coil of pipe, submerged .in the molten lead Yto avoid the use of an extremely large quantity of lead. This filling device 15 displaces some of the lead, causing it to rotect a greater area of the still. The coll of pipe constituting the lling Idevice is capped at its ends, as shown at 16 in Fig. III, to prevent the lead from entering ythe pipe. Anchors 17, secured to the bottom of the still, prevent the hollow filling device 15 from floating on the surface of the molten lead. l I claim: 1. A cracking still provided 4.with'a bou of heavy fusible material on itsbottom wal a heating chamber below said .bottom wall, and means for moving coke-forming substance along the surface of said heavy fusible material. i 2. A cracking still provided with a body of heavy liquid forming a support for thel Y liquid' to be distilled, and a skimmer arranged to move coke-forming, substance alongl the surface of said heavy liquid.

3. A cracking still provided with a body of 4heavy liquid forming a support for the liquid to be distilled, a skimmer-arranged partly within said heavy liquid, and means for reciprocating said skimmer to ,move coke-forming substance along the surface of said heavy liquid.

4. A crackmg still provided with a body n of heavy liquid forming ay support for the liquid to be distilled, a skimmer arranged partly within said heavy liquid, and means for reciprocating said skimmer to move coke-forming substance along the-surface of said heavy liquid, said means including a reversible feed screw fitted to said skimmer.

5. A cracking still provided'with a body f `tom, a body of heavy fusible material' arranged in the still and forming a support for the liquid to be distilled, said fusible material being so heavy that the coke-forming substance will float on its surface, andI a skimming device forcing such coke forming substance toa oint directly above one of the end walls otpsaid heating chamber.

. In testimony that I claim the foregoing I hereunto aiiix my signature..

JOHN w. consi?, an.

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