US2220691A - Conversion of hydrocarbon oils - Google Patents

Description

Nov. 5, 1940. K. SWARTWOOD CONVERSION OF HYDROCARBON OILS Original Filed Sept. 18, 1935 DIST ILLING AND FRACTIONATING COLUMN RECEIVER DISTILLING COLUMN FURNACE INVENTOR KENNETH SWARTW A ORNEY Patented Nov. 5 1940 UNITED sra'res 2,220,691 CONVERSION OF HYliROC/ARBON OILS ,Kenneth Swartwood, Chicago, Ill., assignorto Universal OilProducts Company, Chicago, 111., a corporation of Delaware Application September 18, 1935, Serial No. 41,007 Renewed February 17, 1939 4 Claims. (Cl. 196-49) This invention particularly refers to an improved process for the distillation of hydrocarbon oils of relatively wide boiling range, such as crude petroleum, topped crude and the like for the recovery therefrom of desirable relatively highboiling components which are subjected to rela-' tively mild conversion and subsequent distilla tion for the production of such materials as asphaltic residue, good quality fuel oil and/or lubrieating oil and conversion of the lower boiling fractions of the charging stock, together with intermediate liquid conversion products ofthe process, for the production of high yields of motor fuel of good anti-knock value.

Many crudes and topped crudes containing appreciable quantities of relatively low-boiling components suitable for conversion to produce high yields of desirable light distillate products, such as motor fuel of good antiknock value, also contain appreciable quantities of higher boiling components which, when subjected to the same conversion conditions as its lower boiling components, would yield primarily coke and, gas but which may be subjected to relatively mild conversion and subsequent distillation for the production,

depending upon its characteristics, of such materials as asphaltic residue, good quality fuel oil, lubricating stockand the like. It is the purpose of the present invention to provide an'improved process whereby oils of this character are subjected to distillation or topping for the vaporization of a substantial proportion of their relatively lowboiling fractions desirable as cracking stock for the production of high yields of motor fuel, by means of heat recovered from within the same cracking system wherein said low-boiling fractions are subjected to conversion, and to: recover the desirable relatively high-boiling components of the charging stock without contamination thereof with any appreciable quantity of highboiling products resulting from conversion of the lower boiling oils and to subject said high-boiling components to conversion under relatively mild cracking conditions and to subsequent distillation with or without steam, as desired, for the recovery therefrom of desirable high-boiling products and returning any materials vaporized by said subsequent distillation, of lower boiling characteristics than said desirable high-boiling materials, to the cracking system for further treatment In one specific embodiment the invention comprises subjecting a hydrocarbon oil of relatively low-boiling characteristics, recovered from within the system, toconversion conditions ofcracking temperature and super-atmospheric pressure, separating the resulting vaporous and liquid conversion products and subjecting the latter to further vaporization at substantially reduced pressure, removing the resulting non-vaporous conversion'products from the system, subjecting the vaporous conversion products to fractionation whereby their insufficiently converted components are condensed-as reflux condensate, subjecting fractionatedvapors of the desired endboiling point to condensation, recovering the resulting distillate, commingling charging stock for the process, comprising a hydrocarbon oil of relatively wide boiling range, with the vaporous conversion products undergoing fractionation, whereby the charging stock is subjected to vaporization and fractionation together with 'the vaporous conversion products, withdrawing from the fractionating step non-vaporous high-boiling components of the charging stock together with any correspondinghigh-boiling components of the reflux condensate, subjecting the same to independently controlled relatively mild conversion conditions of cracking temperature and superatmospheric pressureysubjecting the resulting conversion products to further distillation, recoverering from the distilling step desirable highboiling oils such as, for example, asphaltic residue, good quality fuel oil, lubricating stock and the like, returning vaporous products from the distilling step to the'fractionating stage of the cracking system and supplying selected fractions of the charging stock and intermediate liquid conversion products of the process, of lower boiling characteristics than the c'o-mmingled oils subjected to said relatively mild conversion, to conversion in the first mentioned cracking stage of the system. I l

When desired, said further distillation of the high-boiling oils subjected to said relatively mild conversion-may be accomplished in the presence of steam, particularly in case the oil contains an appreciable quantity of lubricating stock or other materials which it is desired to recover without subjecting the same to excessive conversion, the steam serving as a means of cooling the heated products sufficiently to retard or arrest their further conversion and at the sametime serving to assist their distillation.

On the other hand the high-boiling oils subjected to said relatively mild. conversion, may, when desired, be subjected to subsequent distillation in the presence of air or other suitable oxidizing medium for the purpose of producing asph-altic residue.

The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the features of the invention and the following description thereof embodies various alternative methods of operation which may be employed within the scope of the invention.

Referring to the drawing, hydrocarbon oil of relatively low-boiling characteristics, recovered from within the system and supplied to heating coil I, as will be later more fully described, is subjected therein to the desired conversion temperature, preferably at a substantial superatmospheric pressure, by means of heat supplied from a furnace 2 of any suitable form. The heated products are discharged from the heating coil through line 3 from which they-may be directed either through line 4 and valve 5 into reaction chamber 3 or through line I, valve 8 and line 9 into vaporizing chamber I0.

Reaction chamber 6, when employed, is preferably operated at a substantial superatmospheric pressure and, although not indicated in the drawing, this zone is preferably insulated to prevent the excessive loss of heat therefrom by radiation so that conversion of the products supplied to this zone, and particularly their vaporous components, may continue therein. Both vaporous and liquid conversion products may be withdrawn in commingled state from lower portion of chamber 6 through line I I and valve I2 and directed through line I and line 9 to vaporizing chamber I0 or, when desired, a regulated portion or all of the vaporous conversion products may be separately withdrawn from chamber 6 at any desired point in this zone and directed therefrom, all or in part, either to vaporizing chamber In or to fractionating column l9. Means comprising line I3 and valve I4 are indicated in the drawing whereby vaporous conversion products may be separately withdrawn from the upper portion of chamber 6 and supplied to vaporizing chamber I0.

Chamber II] is preferably operated at a substantially reduced pressure, relative to that employed in the reaction chamber or, in case no reaction chamber is utilized, relative to that employed in the heating coil, by means of which further vaporization of the liquid conversion products is accomplished. Residual liquid remaining unvaporized in chamber I0 may be withdrawn therefrom through line l5 and valve I6 to cooling and storage or to any desired further treatment. Vapo-rous conversion products are withdrawn from chamber I0 through line H and valve I8 and supplied to the lower portion of distilling and fractionating column I9. As previously mentioned, any vaporous conversion products separately withdrawn from chamber 6 may, when desired, be supplied, all or in part, direct to column I9 by well known means, not shown in the drawing.

It is also within the scope of the invention, when desired, to operate chamber I0 for the production of relatively dry coke rather than liquid residue, in whichcase the coke may be allowed to accumulate within the chamber until it is substantially filled or until its operation is completed for any otherreason, following which the chamber may be cleaned and prepared for further operation. A plurality of coking chambers may be employed for this purpose, when desired, although only one is illustrated in the drawing and they may be either simultaneously or alternately operated.

Simultaneous with the operation above described, hydrocarbon oil charging stock for the process, preferably comprising an oil of relatively wide boiling range, such as crude petroleum, topped crude or the like, is supplied through line 20 and valve 2| to pump 22 by means of which it is introduced through line 23 and valve 24 into the lower portion 33 of distilling and fractionating column I9, being directly commingled therein with the relatively hot vaporous conversion products of the .process, whereby it is subjected to vaporization and to fractional distillation therewith. It will be understood, of course, that the charging stock may, when desired, be preheated in any suitable well known manner, not illustrated, prior to its introduction into the fractionator. A substantial proportion of the charging stock comprising low-boiling fractions thereof desirable as cracking stock for the production of high yields of motor fuel, is vaporized in distilling and fractionating column I9 and these materials, ex-

clusive of any desirable light fractions within the I boiling range of motor fuel and of good antiknock value, are condensed-in the upper portions 34 and 35 of the fractionating column, together with insufficiently converted vaporous conversion products of the process of corresponding boiling characteristics. In the case here illustrated, the condensate thus formed is separated by fractional distillation in column I9 into selected relatively low-boiling and high-boiling fractions which are withdrawn from suitable intermediate points in the fractionator, above the respective separating decks or trays 25 and 26, through the respective lines 2'1 and 28 control-led by valves 29 and 30, respectively, to the respective pumps 3| and 32, by means of which they are returned to further conversion within the same system, as will be later more fully described.

The low-boiling condensate formed in the upper portion 35 of column I9 may contain some materials of inferior antiknock value within the boiling range of the desired final light distillate product of the process as well as, when desired, somewhat higher boiling materials such as naphtha, kerosene or kerosene distillate, pressure distillate bottoms and the like. This material, supplied, as previously described, to pump 3 I, may be directed therefrom through line 36 and valve 31 to conversion in heating coil I, in the manner previously described.

Condensate formed in the mid-portion 34 of column I9, preferably comprising intermediate fractions of the charging stock and of the vaporous conversion products of the process supplied to this zone, such as gas oil and any desired higher boiling oils, are supplied to pump 32, as previously described and may be directed therefrom through line 38, valve 39, line 40 and valve 4| to conversion in heating coil 42, or this material may be directed, all or in part, through valve 39 in line 38 into line 44 and thence either through valve 46 in this line into reaction chamber 6 or through line 41 and valve 48 into vaporizing chamber I0.

Heating coil 42, when such a zone is employed, is located within a furnace 43 of any suitable form by means of which sufiicient heat is supplied to the oil passing through the heating coil to subject it to the desired conversion temperature, preferably at a substantial superatmospheric pressure, and the heated products are discharged from heating coil 42 through line 44 and valve 45 and may be directed either through valve 46 in this line into reaction chamber 44 or through line 41 and valve 48 into vaporizing chamber II]. It will be understood, of course, that reaction chamber 6 may be utilized as a'z one of continued con-' versionfor the heated products from heating coil 42, either alone or in conjunction withthe heated products from heating coil l, or thatthe heated products from heatingcoil 42 may, when desired, be supplied to vaporizing chamber i0 regardless of whether or not. the reaction chamber is utilized for the continued conversion of the heated products from heating coil l.

It is also specifically within the scope of the present invention, particularly in case it is not desired to subject materials of inferior antiknook value within the boiling range of the final light distillate product of the process to further conversion or reforming within the same system, to

eliminate removal of a separate low-boiling stream of reflux condensate from the upper portion 35 of the *fractionator and to withdraw the total reflux condensate tobe subjected to further conversion within the system from the intermediate .portion 34 of the fractionat'or to pump 32, in the manner previously indicated, and to supply this material through line 38, valve 39, line 49,

valve 50 and line 36 to heating coil l for furtherv conversion, in which case the use of heating coil 42 will be obviated and separating deck 25 will be eliminated from column I9.

Fractionated vapors of the desired end-boiling point, preferably comprising materials within the boiling range of motor fuel and of good antiknock value, are withdrawn, together with uncondensable gas, from the upper portion of fractionating column I!) through line 51 and valve 52 to .be subjected to condensation and cooling in condenser 53. The resulting distillate and gas passes through line 54 and valve 55 to collection and separation in receiver 56. Uncondensable gas may be released from th receiver through line El and valve 58. Distillate may be withdrawn from. receiver 56' through line 59 and valve 60 to storage or to any desired further treatment. When desired, a regulated portion of the distillate collected in receiver 56 may be recirculated to the upper and/or intermediate portion of column I9 to serve as a refluxing and cooling medium therein to assist fractionation of the vapors.

The components of the charging stock remaining unvaporized or which are vaporized and again condensed in the lower portion 33 of distilling and fractionating column l9, together with any high-boiling components of the vaporous conversion products separated therefrom in this'zone,

are withdrawn from the lower portion of the column through line BI and valve 62 to pump 63, by means of which they are fed through line 64 and valve 85 to heating coil 6'6.

Heating coil 66 is located within a-suitable furnace 67 which supplies the required heat to the relatively high-boiling oils passing through the heating coil to subject the same to relatively mild conversion conditions of cracking'temperature and superatmospheric pressure. Conversion conditions employed in this zone are preferably within the range of those ordinarily identified with viscosity breaking operations whereby mild conversion of the relatively high-boiling oils is accomplished without any substantial production of low-boiling products such as motor fuel. When desired, steam may be supplied to heating coil 66 through line 68 and valve 69 to commingle with the oil undergoing conversion in this zone and temper the conversion reaction in order to avoid excessive thermal decomposition of the oil in the heating coil.

The heated products are discharged from heatthis zone.

ing coil 66 through line wand valve H into the loweror va'porizin'gsection 12 of distilling column 14 wherein substantial vaporization and distillation of the heated products is accomplished and wherein their vaporous and non-vaporous components are separated. Steam may also be supplied, when desired, to the lower portion of column 14 through line 15 and valve 76, serving both as a means of cooling the conversion products supplied to this zone from theheating coil and as a means of assisting vaporization in this zone; Line 15 and valve 16 may also serve, when desired, as a means of introducing air or any other suitable oxidizing medium into direct contact with the residual liquids undergoing vaporization in chamber 12 in order to effect their reduction to asphaltic residue.

- Non-vaporous components of the heated products supplied to, th vaporizing section 12 of column 14 which remain unvaporized in this zone,

comprising, for example, asphaltic residue or good quality fuel oil may be withdrawn from the lower portion of this zone through line 19 and valve 88 to cooling and storage or elsewhere, as desired.

vaporous components of the heated products supplied to zone 12 and vapors evolved in this zone pass through a suitable partition or deck 3! in column 14 into the upper or fractionating section 13 of the column wherein any desirable intermediate fractions of the products from heating .coil 66 such as, for example, lubricating stock they may be supplied to any other suitable point in column l9 by well known means, not shown in the drawing.

It is also within the scope of the present invention, when desired, to separate the condensate formed in fractionating section 73 of column #4 into selected relatively low-boiling and high-boiling components which may be separately withdrawn from suitable intermediate pointsin this zone, although means for accomplishing this are not shown in the drawing. It is also specifically within the scope of the present invention, when desired, although not illustrated, to subject the overhead vaporous products'from column 14 to condensation and return the distillate thus formed either to fractionating column l9, at any desired point .in this zone, or direct to heating coil l or heating coil 42 for further conversion.

The preferred range of operating conditions which may be employed in accordance with the process of the present invention, in an apparatus of the character illustrated and above described,

may be approximately as follows: The first mentioned cracking coil may employ an outlet conversion temperature of from 950 to 1050 F.,

preferably with a superatmospheric pressure, measured at the outlet from the heating coil, of from 200 to 800 pounds, or more, per sq. in., .although, when desired, lower pressures down to substantially atmospheric may be employed in The other cracking coil, when such a zone is employed, may utilize on outlet conversion temperature of from 850 to 950" F., or there- 75 abouts, preferably with a superatmospheric pres sure of from 100 to 500 pounds, or thereabouts, per sq. in. as measured at the outlet from .the heating coil. The reaction chamber, when employed, may ultilize a superatmospheric pressure of the order of 100 to 500 pounds per sq. in. The vaporizing chamber may utilize a pressure ranging from 100 pounds, or thereabouts per sq. in., down to substantially atmospheric and this pressure may be substantially equalized or somewhat reduced in the succeeding fractionating, condensing and collecting portions of the cracking-system. The temperature to which the high-boiling oils from the fractionator of the cracking system are subjected in the heating coil to which they are supplied may range, for example, from 750 to 850 F., preferably with a superatmospheric pressure measured at the outlet from the heating coil of from 50 to 350 pounds, or thereabouts, per sq; in. The succeeding distilling column is preferably operated at a relatively low superatmospheric or substantially atmospheric pressure in order to assist vaporization and fractionation in this zone and to prevent any appreciable further conversion therein of the heated products supplied thereto.

As a specific example of one method of operation-of the present process, the charging stock comprises a California crude of about 16 A. P. I. gravity containing no appreciable quantity of materials within the boiling range of gasoline but containing a high percentage of gas oil and a high percentage of higher boiling fractions including about 25 percent of heavy residue. The charging stock is supplied to the lower portion of the fractionator wherein it is subjected to substantial vaporization by commingling with the hot vaporous conversion products in this zone and its non-vaporous components comprising principally said heavy residual fractions are withdrawn'from the fractionating column, subjected in a heating coil to an outlet conversion temperature of approximately 800 F. at a superatmospheric pressure of about 150 pounds per sq. in. and introduced into a distilling column operated at a superatmospheric pressure of approximately 50 pounds per sq. in. The resulting non-vaporus products comprising good quality fuel oil are recovered from the distilling zone and the vaporous products are returned to the same fractionating zone to which the charging stock is supplied. Components of the charging stock and reflux condensate formed in the fractionlator comprising materials within the boiling range of approximately 575 to 730 F. are subjected in a separate heating coil to an outlet conversion temperature of approximately 930 F. at a superatmospheric pressure of about 350 pounds per sq. in. and the heated products are introduced into the upper portion of the reaction chamber. Lower boiling fractions of the charging stock and reflux condensate having a boiling range of approximately 400 to' 575 F. are subjected in another separate heating coil to an outlet conversion temperature of aproximately 950 F. at a superatmospheric pressure of approximately 400 pounds per sq. in. and the heated products from this zone are also introduced into the reaction chamber. The reaction chamber is maintained at a superatmospheric pressure of approximately .350 pounds per sq. in. and both vaporous and liquid conversion products are withdrawn in commingled state from this zone and introduced into a reduced pressure coking chamber operated at a superatmospheric pressure of approximately 50 pounds per. sq. in. This'ipressure is substantially equalized in thesucceeding fractionator to which the vaporous productsfrom the coking zone are supplied. This operation may yield, per barrel of charging stock, approximately 55 percent of 400 F. end-point motor fuel having an octane number of approximately by the motor method, approximately 45 pounds of low volatile petroleum coke and about 17 percent of premium fuel oil, the remainder being chargeable, principa1ly,"to uncondensable gas.

This application is a continuation in part of my earlier application Serial No. 757,511, filed December 14, 1934.

I claim as my invention:

1. In a processfor the conversion of hydrocarbon oils wherein an oil is subjected to conversion conditions of cracking temperature and superatmospheric pressure, the resulting vaporous and liquid conversion products separated in a separating zone, the vapors subjected to fractionation in a fractionating zone whereby their insufficiently converted components "are condensed as reflux condensate, reflux condensate formed by said fractionation subjected to said conversion, fractionated vapors of the desired end-boiling point subjected to condensation and the resulting distillate recovered, the improvement which comprises introducing charging stock for the process, comprising a hydrocarbon oil of relatively Wide boiling range, into the fractionating zone and commingling the same therein with the vaporous conversion products subjected to said fractionation, whereby the charging stock is subjected to vaporization and to fractionation therewith, subjecting the resulting non-vaporous high-boiling components of the charging stock, together with any commingled high-boiling components of the reflux condensate of corresponding boiling characteristics, to independently controlled relatively .mild conversion conditions of cracking temperature and superatmospheric pressure, subjecting resulting products to further distillation in a zone apart from said separating zone whereby to separate therefrom desirable high-boiling components uncontaminated with residual products rom said separating zone, supplying vapors from said further distillation to the fractionating step to which the charging stock is supplied, separate- 1y recovering said liquid conversion products and said desirable highg-boiling components, separating into selected relatively low-boiling and high-boiling fractions the portions of the reflux condensate and of the charging stock of lighter character than 'said non-vaporous high-boiling components of the charging stock and separately subjecting said selected low-boiling and highboiling fractions tofurther conversion within the same cracking system.

2. A hydrocarbon oilconversion process which comprises introducing to a fractionating zone cracked vapors and charging stock for the process comprising an oil of relatively wide boiling range, fractionating the vapors and charging fractionating zone, Separately subjecting said heavy liquid fraction to relatively mild conversion conditions, separating the products of the last-mentioned step into vapors and liquid in a vaporizing zone apart from said separating zone whereby to produce a liquid residue uncontaminated with residual conversion products from said separating zone, supplying vapors from said vaporizing zone to said fractionating zone for fractionation therein, and separately recovering the cracked residue from said separating zone and the liquid residue from said vaporizing zone.

3. The process as defined in claim 2 further characterized in that the cracked residue is reduced to coke in said separating zone and recovered as a solid product. i

4. The process as defined in claim 2 further characterized in that the cracked residue is withdrawn and recovered from said separating zone as a liquid product.

KENNETH SWARTWOOD.

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