US2188312A - Conversion of hydrocarbon oils - Google Patents

Description

ATTORNEY LoqlsC Rusm INVENTOR MLN/Maw mm. A mv Sv :if

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Jan. 30, 1940. c. RUBIN CONVERSION OF HYDRQCARBON OILS Filed April 22 1936 -..-N- ,mw L u Y Y Si--- A Y 1I n C ---x Nm I I ,wb

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25 ess as hereinafter described.

able for improving the anti-knock properties thereof a desired amount and the products from the reforming coil thereafter combined with the products resulting from the initial mild cracking treatment prior to their introduction into the distilling chamber.

Having described the general nature and objects of my invention I will now proceed with a more specific detailed description thereof in which reference will be made to the accompanying drawing which is a diagrammatic and simplified illustration of an apparatus'suitable for carrying the invention into effect.

The apparatus may comprise in general the combined crude distilling and fractionating tower I0, a low-temperature cracking furnace II, a combined low-.pressure vapor separator and fractionating tower I2, a fractionating tower I3 connected therewith, a high-temperature furnace I4, a separating chamber I5 connected therewith, a fractionating tower I6 associated with said reaction chamber together with the necessary pipe lines, valves, controls, heat exchangers and other appurtenant equipment for carrying out the proc- Fresh charging oil, which may comprise crude, topped crude or similar stock having lighter and heavier constituents, after preliminary heating to a distilling temperature, for example, by indirect heat exchange with hot products resulting from the subsequent cracking steps or after having been heated in a directly-fired coil, or both, is forced through charging line 20 by means of pump 2 I .to the bottom section of the combined crude-distilling and fractionating tower I0 wherein the crude voil is subjected to distillation. Vapors liberated as a result of the distillation in the bottom section of the tower I0 pass upwardly through trap-out tray 23 and are subjected to fractionation in the intermediate section 24 of the tower. Condensate resulting from the fractionation in the intermediate section 24 of the tower I0 collects in trap-out tray 23 and may be withdrawn therefrom through line 25 and sub- .jected to further cracking treatment as hereinafter described. This condensate may have an initial boiling point of from 400 to 500 F., for example, and an end point of about 650a F. Vapors remaining uncondensed in the intermediate section 24 of the tower I0 pass upwardly through trap-out tray 26 and are subjected to fractionation thereabove to condense heavy naphtha constituents thereof. condensate formed in the upper portion of the tower I0 collects in trap-out tray 26 and is withdrawn therefrom through line 21 and subjected to further treatment as hereinafter described. This condensate may have an initial boiling point of from 200 to 300 F. and an end point of from 400 to 500 F. Vapors remaining uncondensed in the upper portion of the tower II) pass upwardly through line 28 to condenser 29- wherein the light naphtha constituents of the original charging stock are condensed. The condenser20 discharges into receiving drum 30 wherein the final distillate separates from gases. Gases are removed Afrom receiving drum 30 through line 3I and the desired light naphtha distillate through line 32. Residue resulting from the distillation of the original charging stock in the bottom portion of conditions for the purpose of forming intermediate cycle stock which is amenable to hightemperature cracking treatment. The products from the heating coil 35 may be passed directly through line 36 to theA lower section of the combined separating and fractionating tower I2 or they may be passed through line 31 to a reaction chamber 38 wherein the desired conversion may be carried to completion. In such case the products from the reaction chamber 38 are withdrawn therefrom through line 39 which merges with line 36 and are conveyed lto the tower I2 as hereinbefore described. Products from the heating coil 35, or from the reaction chamber 38, upon being introduced intothe bottom section of the tower I2 are subjected to drastic distillation to vaporize all distillable fractions therefrom and produce a heavy viscous residue. In order to effect this desired drastic distillation the products from the heating coil 35 are merged with lighter gaseous products before being introduced into the chamber I 2. These gaseous products are preferably products obtained from the reforming of the heavy naphtha constituents as hereinafter described. Residue resulting from the drastic distillation of the products from the heating coil 35 or the reaction chamber 33 are withdrawn froxnthe bottom of tower I2 through line 40 and are cooled and passed to storage or subjected to further treatment as desired. y

Vapors resulting from the distillation in the bottom of the tower I2 pass upwardly through trap-out tray 4I located therein and are subjected to initial fractionation in the upper section thereof, Heavy condensate formed in the upper section of the tower I2 collects in trap-out tray 4I and is withdrawn therefrom through line 42. This heavy condensate may havean initial boiling point of above 650 F., for example. Condensate withdrawn from trap-out tray 4I is returned via line 42 to a second heating coil 43 located in the low-temperature furnace I I wherein it is subjected to further mild cracking treatment to form lighter constituents amenable to hightemperature treatment. Products from the heating coil 43 are discharged through transfer line 44 and may be passed through lines 45 and 31 to the reaction chamber 38 with products from the heating` coil 35, or the products may be introduced into the transfer line 36 wherein they cornbine with the products from the heating coil 35.

Vapors remaining uncondensed in the upper section of the tower I2 pass over therefrom through line 4l to fractionating tower I3 wherein they are subjected to further condensation to separate a light intermediate fraction. This fraction may have, for example, an initial boiling point of from 400 to 500 F. and an end point of about 650 F. Condensate formed in the lower portion of the tower I3 is withdrawn therefrom through line 48 and is merged with condensate formed in the intermediate section of the crude distilling chamber Il) and withdrawn therefrom through line 25.

The fractionating tower I3 may be provided with a trap-out tray 49 and positioned to collect heavy naphtha constituents of the vapors, or the fractionating tower I3 may be regulated to take overhead a distillate of the desired end point. Vapors remaining uncondensed inthe tower I3 pass overhead through line 5I to a condenser 52 wherein gasoline constituents thereof are condensed. Condenser 52 discharges through line 54 to a receiver 55 wherein gases and distillate separate. Distillate is withdrawn from receiver 5S through line 55, andfgases' are vented through pipe 5l "provided with valve :58 for maintaining the desired back pressure on the fractionating tower I3.

"Combined condensate from the' bottom of iractionating .tower I3 and the trap-'out tray 23 contlnues through line 48 and .is forced by means of pump 59V through heating coil 0I located in the high-temperature furnace I4. The oil, during its passage through the heating coil '61, is subjected to' high temperature, high crack per pass condition's to effect maximum conversion into gasoline of high anti-'knock properties; Products from the heating coil 6I dischargethrouglr trans'- ter line 6.2 to separating chamber I5, wherein vapors and residue separate. Residue from the tower i5 is withdrawn through line B3 andma'y befcooledwand withdrawn from the .system or subjected tor further treatment as desired; Vapors liberatedtheseparatingchamber I5 pass overhead through line S4 to fractionating tower i6 wherein they are subjected to fractionation to condense insmtliciently converted constituents therefrom'. Condefrnzate resulting from the fractionation in tower i6 is withdrawn from the' bottom thereof through line 65 and is returned to line 48 for urthc-:r treatment in the heating coill. Y

Vapors remaining uncondensed in the fractionating tower IFS-pass overhead through line 06 17o-condenser 61 Whereinfthe desired distillate con- Condenser v15'! discharges to a receiving drum 68 wherein gases andy distillate separate. Gases pass overhead through line S9 and are withdrawn from the system and the distillate is removed from the system through line 1 I.

. Heavy naphthaconstituents` resulting from, the distillation of the crude oil in tower l0 and collected on trap-out tray 2li-are withdrawn through line 21- and passed by means ofA pump 'i2 to a second heating coill 'I3 Alocated in the hightemperature furnace Illn whereinv they are subjected to reforming conditions of temperature and pressure. Products from the reforming coil 13 discharge through line T14, and all or part thereof are passed through line 15 to transfer line 36 wherein they merge withproducts therein andy aid inthe distillation of theheavy products as hereinbefore described; A` portion of the in carryingout my invention toobtain the greatest advantagesv therefrom, it being understood that the val-ues given herein are illustrative rather than limitati-ve. For example, the original crude oil, which may be anyof common Acrude oils, such as Mid-Continent` crude, is initially heated to a distillingtemperature'of from 600 to '700 F. or thereabout before being discharged into the distilling` andl fractionating chamber I0. The distiilation of the' crude charge in the 'tower I0 may be controlled tovfaporize ally constituents boiling below 650'.n to750 F. Unvaporized reduced cxilide stock from the bottomv of' the tower I0 having an initial `boiling point oiD4 from 650 to 7009 F. 'or thereabout maybe heatedfto an 'out'- lettemperature of from 875 to' 900 F'. during its passage through the heating coil 35 provided 'the time of treatment is limited to' avoid excessive coke deposition. The temperature and time of treatment of the reducedcrude in the' heating coli 35er thel heating coil 35 and reaction chamber 38 may be regulated with respect to each other to' produce from 20 to 30% oi constituents boiling below the initial' boiling point of the" reducedcrude of* which fromL 8 to 15% thereof may boii within th'erang'e olf gasoline.

The products from the heating coil 35' or from .the reaction chamber 38, 'as the case be', after being introduced through the bottom section of the separating and fractionating tower 'I2 are4 subjected to distillation tor remove all distillable fractions therefrom and form aheavy residual product having, 'for example, a viscosity' measurement of above 3000 seconds at 122 F. as measured by a Saybolt Furol viscosimeter.

Heavy condensate `collected in the trap-'out tray 4I of the tower -I'2` may have an initial boiling point vof above 600 F. This condensate, during its passage `through the heating coil 43; may be heated to a temperature ranging from about 850 to 925 F., for example, and for a time sufcent to effect from 10 t0 20% thereof intog'soline constituents. The oil, during its passage through the heating coil 43, is preferably maintained under relatively high pressure', such as a pressure in excess of 400 pounds/per square' inch.

condensate collected inthe bottom'of fractionating Vtower I3 may have an initial boiling' point ranging from aboutV 250 to 500 F. and an end point'of 650 F. This fraction, combined with the fraction taken from ,trap-out tray 23 of the `crude distilling` tower I0 during its passage through heating coil I6i may kie-subjected to a temperature ranging fromv850 1:01050@ F. or more and subjected to cracking conditions' and temperatures for a time adequate to effect to from 20 to 40% or more into gasoline constituents.

The heavy naphtha fraction separated from the original crude stock in the initial distilling zone I0 in trap-out tray 216 and, if desired, the heavy naphtha constituents separated in the fractionating tower I 3 may be subjected to atemperature ranging from 950 to 1100 F. during their passage through the heating coil 13.

The pressure maintained on differentparts'of the equipment is not critical to my process and mayv vary over a Wide range depending on the nature of stock treated',oha'racter of thefnal products desired and other factors. In general the outletpressures of the heatingy coils and the cracking portion of the equipment -are materially higher than'that maintained on the distilling. and fractionatingchambers; The outlet pressure on the heating coils may range, for example, from 300 to 1000 pounds or more per square inch'. In practice it is usually preferred to carry higher pressures on coils `6I and 13located in the hightempera-ture furnace I4 than are carried on coils 35 andu43 in the low-temperature furnace II in order to reduce gas loss. The pressure' on heatingY coils 6I and 13 may range from 500 to 1000 poundsy per square'inch, and the outlet pressure on heating coils 35 and 43`may range from 300 to 500 poundsper square inch.

The" pressure on the crude distilling tower IIL the distilling tower I 2 and fractionating tower 13 is preferably materially' lower and mayl range from sub-atmospheric to about 300 poundskper square inch.` The pressure on the separator I5 and fractionatlng tower I6 maybe somewhat higher, such as from 200 to 500 pounds per square inch.

While the above conditions of temperature,

pressure and conversion per pass are .given as an aid in operating the invention, it will be understood that the conditions may vary Widely depending upon the character of the original stock and the character of the desired end products.

Having described the preferred embodiment of my invention it will be understood that it embraces such other modifications and variations as fall within the spirit and scope thereof and that it is not my intention to unnecessarily limit the invention or dedicate any novel features thereof.

I claim:

v1. In the cracking of hydrocarbon oils, the process that comprises subjecting crude petroleum residuum to cracking in a primary viscositybreaking Zone under conditions to effect conversion into a high yield of gas oil constituents, directing the resultant viscosity-broken products into a'first separating zone wherein vapors separate from residue, passing the separated vapors to a first fractionating zone wherein the vapors are subjected to fractionation to form therein a heavy gas oil fraction, a lighter gas oil fraction, a heavy naphtha fraction and a final gasoline distillate, subjecting the heavy gas oil fraction to cracking temperature in a secondary viscositybreaking zone under conditions to effect conversion into a high yield of lighter gas oil constituents, directing the resultant viscosity-broken products into said rst separating zone, subjecting said lighter gas oil fraction to cracking temperature in a separate cracking zone under conditions of high cracking per pass to effect conversion into gasoline of high anti-knock quality, 'directing the resultant cracked products into a second separating Zone wherein vapors separate from residue, fractionating the separated vapors in a second fractionating Zone to recover the desired high anti-knock gasoline product, subjecting aforesaid heavy naptha fraction to cracking temperature in a separate reforming Zone under conditions adequate to effect reforming of the' gasolineV constituents into constituents of increased anti-knock quality and directing the hot products of the reforming into said rst separating zone.

v2. In the cracking of hydrocarbon oils, the process that comprises subjecting crude petroleum to distillation to separate out a crude residuum, a gasA oilfraction and a naphtha fraction, subjecting said crude residuum to cracking in a primary viscosity-breaking zone under conditions to effect conversion `into a high yield of gasoil constituents, directing the resultant viscosity-broken products into a v first separating Zone wherein vapors separate from residue, passing the separated vapors to a first fractionating zone wherein the vapors are subjected to fractionation to form therein a heavy gas oil fraction, a lighter gas oil fraction, a heavy naphtha fraction and a nal gasoline distillate subjecting the heavy gas oil fraction to` cracking temperature in a secondaryviscosity-breaking zone under conditions to effect conversion into a high yield of lighter gas oil constituents, directing the resultant viscositybroken products into said rst separating zone, combining said lighter gas oil fraction with the gas oil fraction obtained from the crude distillationand subjecting the combined gas oil constituents to cracking temperature in a separate cracking zone under conditions of high cracking per pass to eifect'conversion into gasoline of high anti-knock i quality, directing the resultant cracked products into a second separating zone wherein vapors separate from residue, fractionating the separated vapors in a second fractionating zone to recover the desired high anti-knock gasoline product, combining aforesaid heavy naphtha fraction with the naphtha fraction obtained from the crude distillation and subjecting the combined naphtha fractions to cracking temperature in a separate reforming zone under conditions-adequate to effect reforming ofthe gasoline constituents into constituents of increased anti-knock quality and directing the hot products of the reforming into said rst separating zone.

3. In the cracking of hydrocarbon oils, the process that comprises subjecting crude petroleum to distillation to separate out a crude residuum, a gas oil fraction and a naphtha fraction, subjecting said crude residuum to cracking in a primary viscosity-breaking zone under conditions to effect conversion into a high yield of gas oil constituents, directing the resultant viscositybroken products into a first separating zone wherein vapors separate from residue, Withdrawing said residue from the process, passing the separated vapors to a rst fractionating zone wherein the vapors are subjected to fractionation to form therein a heavy gas oil fraction, a lighter gas oil fraction and a nal gasoline distillate, subjecting the heavy gas oil fraction to cracking temperature in a secondary viscosity-breaking zone under conditions to effect conversion into a high yield of lighter gas oil constituents, directing the resultant viscosity-broken products into said rst separating zone, combining said lighter gas oil yfraction with the gas oil fraction obtained from the crude distillation and subjecting the combined gas oil constituents to cracking temperature in a separate cracking zone under conditions of high cracking per pass to effect conversion into gasoline of high anti-knock quality, directing the resultant cracked products into a second separating zone wherein vapors separate from residue, fractionating the separated vapors in a second fractionating zone to recover the desired high anti-knock gasoline product, subjecting aforesaid naphtha fraction from the crude distillation to cracking temperature in a separate reforming zone under conditions adequate to effect reforming of the gasoline constituents into constituents of increased anti-knock quality and directing the hot products of the reforming into said rst separating zone. i

4. In the cracking of hydrocarbon oils, the process that comprises subjecting crude petroleum to distillation to separate out a crude residuum and a condensate, subjecting said crude residuum to cracking in a primary viscositybreaking zone under conditions to effect conversion into a high yield of gas oil constituents, directing the resultant viscosity-broken products into a first separating zone wherein vapors separate from residue, passing the separated vapors to a rst fractionating zone wherein the vapors ar'e subjected to fractionation to form a heavy condensate and a lighter fraction, subjecting said heavy condensate yto cracking temperature in a secondary viscosity-breaking zone under conditions to effect conversion into a high yield of lighter gas oil constituents, directing the resultant viscosity-broken products into said first separating zone, combining said lighter fraction with said condensate obtained fromk the crude distillation and passing the combined oils to a recycling cracking zone wherein the oil is subjected to cracking temperature at superatmospheric pressure under conditions of high cracking per pass to effect conversion into gasoline of high antiknock quality, directing the resultant products from said recycling cracking zone to a separate separating zone wherein separation of vapors from residue takes place, passing the separated vapors to a separate fractionating zone and subjecting them to fractionation therein to separate a reflux condensate from lighter products and cycling said reflux condensate to the recycling cracking zone.

5. In the cracking of yhydrocarbon oils, the process that comprises primarily separating crude petroleum into vapors and residue and fractionating the separated vapors to form a gas oil fraction and a naphtha fraction, subjecting resultant crude residue to cracking in a primary viscositybreaking zone under conditions to eiect conversion into a high yield of gas oil constituents, directing the resultant Viscosity-broken products into a first separating zone wherein vapors separate from residue, passing the separated vapors to a rst fractionating zone wherein the vapors are subjected to fractionation to form a heavy condensate, a lighter gas oil condensate and a naphtha fraction, subjecting said heavy condensate to cracking temperature in a secondary viscosity-breaking zone under conditions to effect conversion into va high yield of lighter gas oil constituents, directing the resultant viscositybroken products into said first separating zone, combining said gas oil condensates obtained from the crude distillation and from said first separating zone and passing the combined oils to a separate cracking zone wherein the oil is subjected to cracking temperature at superatmospheric pressure under conditions of high cracking per pass to effect conversion into gasoline of high anti-knock quality, directing the resultant products from said separate cracking Zone to a second separating zone wherein separation of vapors from residue takes place, passing the separated vapors to a separate fractionating zone and subjecting them to fractionation therein to separate a reflux condensate from lighter products, cycling said reflux condensate to said separate cracking zone, combining said naphtha fractions obtained from the crude distillation and from said first fractionating zone and subjecting the naphtha mixture to cracking temperature in a separate reforming zone under conditions adequate to eifect reforming of the gasoline constituents into constituents of increased anti-knock quality and directing the hot products of reforming into said first separating zone.

LOUIS C. RUBIN.

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