US1258190A - Art of cracking hydrocarbons. - Google Patents

Description

J. W. COA'SY, 1n.

AHUF CRACKING HYDRCARBONS.

Patented Mar. 5,1918.

APPLIICATION FILED MAR. 22. 19|?. 1,258,190.

Umtrnn STATES PATENT` onirica. I

JOHN W. COAST, JR., OF TU LSA, OKLAHOMA, ASSIGNOIR T0 THE PROCESS COMPANY, A

CORPORATION OF MARYLAND.

ABT OF CRACKING HYDROGARBONS.

To-all 'who-m t may concern.' Y

Be it known that I, JOHN W. CoAs'r, Jr., a citizen of the United vStates of America, a resident of Tulsa, in the county of Tulsa, State of Oklahoma, have invented certain new and useful Improvements in the Art of Cracking Hydrocarbons, of which the following is afull, clear, and exact description, reference being had to the accompanying drawing, forming a part of this specification;

My invention relates to improvements in the art of cracking hydrocarbons, and more particularly to a method of protecting stills from the'injurious effects of coke ortarry coke-forming substances.

When high boiling point petroleum hydrocarbons are vaporized and cracked in the ordinary cylindrical still, heavy cokeforming 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 sufficient quantity has accumulated, the still bottom will become red hot. lSome u a rupture at the overheated portion of the still. In actual practice', the coke accumulates on the hot still bottom when the oil in thel still is maintained at a high temperature and under a high pressure, thus rendermg the cracking operation quite dangerous. On account ofthe danger, and foreconomic reasons the coke is usually removed from the still at frequent intervals.

The main object of my. inventionfis to prevent the coke, or tarry coke-forming. substances from accumulating on the stillbottom where the heat is transmitted tothe still. In the preferred form of the invention, this is accomplished -by maintaining a body of heavy liquid in the bottom of the still, floating the oil to be distilled on said heavy liquid and transmitting heat through the heavyg'liquid to vaporize the .oating liquid. The heavy liquid, preferably molten metal, interposed between the still bottom and the oil, prevents the cokeforming substance from v reaching the bottom Vof the still. Since theheat 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 By preventingY Specification of 'Letters Patent. Application ledlMarch 22, 1917. Serial No. 156,649.

Patented Mar. 5, 1918.

be overheated by the temperature to which it is ordinarily subjected.

Figure I is a diagrammatical view of a cracking apparatus embodying thel features of my invention.

Fig. II is a transverse section ofthe still taken on the line II--II, Fig. I.

Fig. III is a detail view of the filler vwhereby the heavy liquid is displaced to area of the still botcontact with a greater tom.

The still 1, arranged above a heating l chamber 2, is connected by means of an air cooled vapor pipe' 3 toa reflux condenser 4. 5 designates a vapor pipe leading from the reflux condenser to a 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 reiux condenser, and it is inclined to allow the condensate to How backwardly to the still.

The apparatusrI have shown is particularly adapted for use in cracking high boiling point products of distillation such, for example, as the distillates or residues resulting from the distillation of the crude petroleum. The substances to be treated are introduced into the still in any suitable manner, and any desired pressure may be obtained by regulating a valve 8, preferably located in the vapor pipe 5. The pressure in the still is preferably greater than fifty' pounds per square4 inch, and the temperature of 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 thev vapor pipe 3 and v reux condenser 4 to the pipe 5, leading tothe main condenser 6. The relativelyjhigh 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 reflux condensate includes al large percentage of heavy coke-formn fractions, commingled with lighter fractlons, which may be redistilled to form part vof the low boiln point product.

In the preferred form o the invention, the 'end portions of the bottom are ber, an thsefwalls protect said end porseated u on the walls 9 of the heating chamtio'nsi'from the intense heat of thev heating chamber. The heat is transmitted directly through lthe middle portion of the still bottom, and the protected end portions of the stillxare maintained `in a relatively cool condition. l v

A body of heavy liquid."10,=preferably a' readily fusible metal, for example, molten lead,.is ymaintained'in the bottom :of thestillf- The' oil to-be distilled iioats upon the surface-c ofthe molten lead'10, and'the Aheavy coke#- forming fractions whichl dro V.by gravity to the bottom of the'oiL, also oat upon the lead. The molten' lead thus preventsthe coke-forming substance from reaching the hot still bottom. The heat' is transmittedl from' the still bottom, through the molten 'lead to the floating oil. Owingto the high temperature, the lead. is circulated and ay i5 tated so as to very effectively transmlt t eheat to the oil.'4

. The coke is not a .ood conductor of heat;

and fitiis, therefore, circulated along the sur? face of the lead to points directly above the Walls 9, Where it will not materially interfere with the transmission of heat fromtlie4r heating chamber to the oil.

The means forl circulating o r skimming" the coke comprises a skimmer 11 tted t'o a.l rotary feed screw 12 which extends through a stuiing` box 13 atone end of the still..

Gearing -12 may beoperatedin any suitable manner to rotate the. feed screw 12.' Thisl 'feed screw is reversible, so that it ma vbe actuated to reciprocate the skimmer 11 romV one endl portion of the still to the other. Stationary rods 14 prevent the skimmer 11' from turning on the feed scre1vv12.v The lower portion of the `skimmer extends entirely across the lower portion of the still,-

and it' also'extends into the molten lead 10.

By confining the oil and inolten lead, as herein shown and-described, I preventthe vapors', generated in the' still, fromipassing into, or bubblingthrough the moltenliea'd.

The` vapors are discharged from the upper portion of thel still -at av poi'ntlabovethe ilji 15 designates a filling device, in the form of .a. coil of quantity Aof lead. This filling device 15 displaces some of theD lead, causing 1t to protect a greater areaof the still.- The c oil of pipe constituting the filling device is capped i e, submerged in the molten lead to .avoi t e use'of an' extremely 'large' the device 15 from flating'on Vth's'urface o the molten lead." Q

I claim--' v 1. In the artv of crackingwand distilling hydrocarbons, the method which comprises maintaininga body of heavy liquid on the bottom of a still, floating the liquid to be cracked and distilled on saidheavy liquid,

transmitting heat through said heavy liquid.

to vaporizc the oating liquid, collecting coke-forming substance on the surface of the heavyliquid at the bottom of said float- 1n 'I liquid, circulating such coke-forming" su stance between the heavyliquid and the oatin liquid 'to facilitate the transmission-o heat from said heavy liquid to said voating"liquid, maintainin the contents of thestill under ressure, and 'vapors from t e still at a point above the floating liquid.

` 2.' The method of'distilling and cracking' hydrocarbons -which comprises -maintaining a body of heavy liquid on the bottom of a still' floating. the liquid to be distilled and crac ed yon said heavy liquid, 4transmitting heatI through` the still bottom and through discharging the *saidf heavy liquid to vaporize the floating liquid, discharging thevapors. from the still -at a plae above the floating .liquid without conducting said vaporsv into said heavy hquid, collecting' coke-forming substance on the! surface ofthe heavy liquid, and v.forcing such coke-forming substancealong the surV of the still.

I -testimon that vI claim? the foregoing h eeuntoa mv signature.

' JOHN COAST, JR.'

*face of said heavy liquid tothe end portions

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