US2052518A - Art of converting hydrocarbon oils - Google Patents

Description

Aug. 25, 1936.

R. F. RUTHRUFF ART OF CONVERTING HYDROCARBON OILS Filed Aug. 4; 1930 2 Sheets-Sheet l I fiae @W Aug. 25, 1936. F, RUTHRUFF 2,052,518

ART OF CONVERTING HYDROCARBON OILS Filed Aug. 4, 1930 2 Sheets-Sheet 2 Condemero. .5 Qrzderzsens,

Zerz %ra 1 m LZZZM Patented Aug. 25, 1936 PATENT OFFICE I ART OF CONVERTING HYDROCARBON OILS Robert F. Ruthrufi, Hammond, Ind., assignor to Standard Oil Company, Whiting, Ind., a corporation of Indiana Application August 4,

2 Claims.

The present invention relates to improvements in the production of gasoline or other desired light hydrocarbons from heavier hydrocarbon oils, and more particularly to such conversion processes involving a cycle of operations whereby fresh stock introduced into the system is completely converted intothe desired light hydrocarbon products, such as gasoline, except for such portions thereof as are converted to a solid residuum or coke and to gas.

The invention will be fully understood from the following description, illustrated by the accompanying drawings, in which} Figure 1 is a diagrammatic showing of a layout of apparatus for carrying the invention into effect; and

Fig. 2 is a diagrammatic showing of a modified layout of apparatus embodying the invention.

Referring more particularly to Fig. l of the drawings, the numeral 5 indicates a receiving or mixing tank, to which the fresh'stock for the system, suitably a heavy residual oil, is supplied through the line B. The heavy oil thus employed may suitably be a residuum, for example, of the character of one representing 25% or less of a Mid-Continent crude and derived from a distillatory process in which little or no cracking takes place, such as vacuum or steam. distillation.

The residuum thus fed to the mixing tank 5, together with other residual oil products supplied thereto as hereinafter set forth, is removed through the line I and forced by pump 8 through the pipe still furnace 9, in which it is heated to a high cracking temperature, say 840 to 950 F. 35 and preferably 900 to 910 F., with a low outlet pressure, suitably approximately atmospheric or up to 30 lbs. gauge, the operation being preferably as described in the prior application of Robert E. Wilson, Serial No. 329,419. The heated oil leaving the pipe still 9 enters the manifold Ill, from which it is discharged through one or more of lines l2, l3, l4 into one or more of the enlarged chambers or drums l5, l6 and I! respectively. In the drums, which are maintained at elevated c acking temperatures, for example, by the heat of the entering oil products, conversion into a substantially solid residue or coke and into gaseous and vaporous products is completed, substantially as described in the prior application of Robert E. Wilson, hereinbefore ably provided with connections opening into the respective drums at different levels, so that the point of introduction of the entering oil can be raised, if desired, as the level of coke in the referred to. The conduits: I2, I 3 and M are suit- 1930, Serial No. 472,973

drum rises. The heated oil may be fed into the drums I5, l6 and H in rotation, in any two or in all three simultaneously, as desired. Preferably, they are employed in rotation, to permit continuous operation of the pipe still and the '5 required cleaning of the respective drums as they become filled.

Vapors from the drums l5, l6 and H, or such thereof as are in use, pass out through valved connections l8, 19 and/or 20 respectively to a 10 manifold 2|, from which they pass through line 22 to the lower portion of a suitable fractionating column 23, which may be of any desired type, for example, a bubble plate column. In this column the heavier portions of the vapors are 15 condensed, the lighter vapors containing the desired low boiling product together with gas passing out through the vapor line 24 to a suitable condenser 25, in which the desired products are condensed and the cooled products discharged 20 lected therein and discharged through the valved line 28 to a second mixing tank or receiver 29, suitably lagged to prevent loss of heat. If desired, the heavier fractions condensed and collected in the fractionating column 23, and which may include some entrained tar, may be sepa- 30 rately removed therefrom through the valved line 30 'and returned to the mixing tank 5, to be returned to the pipe still 9 and the remainder of the system with the other stocks introduced thereto. It will be understood, of course, that 5 the mixing tank 5 may likewise be suitably lagged or insulated to prevent loss of heat therefrom.

It will be understood likewise that the fractionating column 23 will be at approximately the same pressure as or at a slightly lower pressure 40 than that prevailing in the enlarged drums l5, l6 and ii, for example, at approximately atmospheric pressure or at a pressure up to about 30 lbs. gauge.

The fractions condensed in the fractionating 45 column 23 and discharged into the mixing tank 29 are removed from the latter through the line 3| by pump 32 and forced through pipe still 33, in which they are brought to a cracking temperature, preferably in excess of 850 F. Al- 5 though substantial pressures may be employed at the outlet of the pipe still furnace 33, it is'preferred that the pressure conditions therein be such that the oil passing therethrough is completely vaporized and substantial cracking thereof eifected in the vapor phase. 'I'hemroducts from the pipe still or cracking coil furnace 33 pass through the line 34 into the enlarged. crack ing chamber, 35, in which further cracking takes 1930. For example, with outlet temperatures for 4 the cracking coil as hereinbefore set forth, pressures from atmospheric up to 400lbs. may prevail in the cracking chamber 35. Suitable temperatures and pressures are, for example, a coil outlet temperature of 925 to 950 F. with a pressure in the enlarged chamber of 175 to 300 lbs.,

the cracking chamber being lagged or insulated to prevent loss of heat therefrom.

The gaseous and liquid products of cracking are discharged from the cracking chamber 35 through line 36 provided suitably with a pressure reducing valve 31, and enter a separating chamber 38. The latter may be provided with baflle plates of any suitable design (not shown), for example, doughnut and disk plates or bubble cap plates.

The heavy liquid products separated in the separating chamber 33, which may suitably be at a temperature of 650 to 750 F., are discharged through the line 39 and pass to the mixing tank 5, wherein they are admixed with the fresh stock entering through the line 6 and from which they pass with the latter to the pipe still furnace 9, for treatment as hereinbefore set forth. The vapor products from the separating chamber 33 pass through the vapor line 40 into the fracbe discharged through the line 42, being, for ex-' ample, at a temperature of 600 to 700 F., and may then be passed to the mixing tank 29, to be mixed therein with the reflux condensate formed in the fractionating column 23 and passed to the cracking coil furnace 33. The vapors and gases uncondensed in the fractionating column 4| pass out through the valved line 43, which joins the line 24 leading to. the condenser 25 and separator 21. The desired low boiling products in the vapors are thus condensed and collected with those passing out of the fractionating column 23.

The fractionating column 4| and the separating column 38 may suitably be maintained at pressures approximating those prevailing in the cracking chamber 35 or lower, and are preferably maintained at atmospheric pressure or a pres- ,sure intermediate that prevailing in the fractionas hereinbefore described, the system may be fed with a heavy residual stock, and that the products issuing from the system, apart from the coke formed therein, and the desired low boiling distillate product are entirely gaseous. It will be readily apparent, that if desired, the operation may be modified to secure heavy residual products.

In Fig. 2, there is illustrated an arrangement of 3 apparatus wherein a modified form of the opera-' tion may be carried out.

In the operation illustrated in Fig. 2, a fresh oil, which may be a mixture of light and heavy or residual constituents, such as a crude oil, after suitable preheating as hereinafter described,

is fed through line 50 to the treating or mixing tank 5|, suitably insulated to prevent loss of heat. In the event that light portions of the stock thus supplied are vaporized, the vapors thereof may be removed from the feed tank 5| through the line 52, leading to a suitable condenser and gas separator (not shown). The preheated liquid from the tank 5| is drawn therefrom through line 53 by pump 54, by which 20 it is forced through a pipe still 55, in which it is heated to a temperature sufiicient to vaporize a substantial portion thereof. If desired, steam may be supplied to the oil entering the coil, for example, through line 55*. In the pipe still fur- 26 nace 55, the oil is heated to a temperature such that a sufficient proportion thereof will be vaporized to leave a residue of, say, 27 A. P. I. or lower, for example, a residue corresponding to a 25% or lower residue from Mid-Continent crude 30 oil.

The products from the pipe still 55 pass through line 56 to a separating drum 51, in which the unvaporized portions are separated from the vapors and gases. The latter pass out through 35 vapor line 58 to a fractionating column 59, in which the heavier portions of the vapors are condensed; for example, the gas oil and heavier fractions. If desired, kerosene fractions may be condensed therewith, or may be permitted to pass out through the vapor line 60 with the lighter fractions, to suitable fractional condensers, not shown, wherein further fractional condensation of the light vapors may be effected.

The unvaporized fractions collected in the separating chamber 51 are withdrawn therefrom through line 6| by pump 62 and forced through line 63 to the hot supply tank or mixing tank 64,

for treatment as hereinafter set forth.

The mixing or feed tank 64 is suitably insulated or lagged to prevent loss of heat therefrom. The heavy residual oil is withdrawn from the tank 64 through line 65 by pump 66 and forced through the heating coil 61, from which it is discharged through line 68 to the manifold 69. From the latter the heated oil products are passed through lines 10,-1l and 12 into one or more of the coking drums 13, 14 and 15 respectively, the operation conducted in the coil 61 and the drums 13, 14 and 5 being similar to that hereinbefore described in 60 connection with the coil 9 and the drums |5, I6 and I1 in the operation shown in Fig. 1.

Coke collects in the drums 13, 14 and 15 or such thereof as are in 1 se. The vapor products from these drums or those, of the drums which are in 65 use, pass out through the corresponding lines 16,

11 and/or 18 to the vapor manifold 19, from which they pass through the line into the fractionating column 8|, wherein the vapors are cooled, so, as to condense the heavier portions thereof, the. uncondensed lighter portions comprising the desired low boiling fractions and gas passing out through the vapor line 82 to any suitable condenser and gas separator (not shown).

The condensate formedin the fractionating tower 8|, or the greater portion thereof, is withdrawn through the valved line 83 and passes to the insulated mixingchamber 84, to which may also be supplied the condensate separated in the fractionating column 59 as hereinbefore set forth. This condensate may be withdrawn from the fractionating tower 59 through the valved line 85, by which it is conveyed to the mixing or feed tank 84.

If desired, a small heavier fraction of the condensate formed in the fractionating column 8|,

- which may include any entrained tar-entering the latter, may be withdrawn through the line 86 and discharged into the mixing tank 64, to pass through the pipe still 61 with the heavy residue, as hereinbefore described. I

The heavy distillate fractions from the fractionating column 8 I, together with those from the fractionating column 59, are withdrawn from the feed tank 84 through the line 81 by pump 88 and forced through the cracking coil furnace 89, from which the heated products pass through the line 99 to the cracking chamber 9|, the operation in the cracking coil 89 and cracking chamber 9| being similar to that taking place in the cracking coil 33 and cracking chamber 35 in the operation of Fig. 1, as hereinbefore described. The products from the cracking chamber 9| pass out through the line 92, in which may be provided the pressure reducing valve 93, to a separating column 94, in which a separation of vapor and liquid products is effected, similar to that occurring in separating column 38 in the embodiment illustrated in Fig. 1. The separated residual liquid or tar passes out of separating column 94 through line 95 and is discharged into the mixing or feeding tank 64 from which the heating coil 61 is fed. The vapors pass out of the separating column 94 through line 96, and enter the fractionating column 8| at an intermediate point, cooling and fractionation thereof being effected in said column together with the cooling and fractionation of the vapors received from the coking chambers l3, 74 and/or I5. The heavier fractions of the vapors from the separating column 94 are thus simultaneously condensed and commingled with those from the cracking chambers, as hereinbefore set forth, and the resulting condensate passes together throughtheline 83 to the feed tank 84 for the cracking coil 89. Similarly,the uncondensed vapors and gas derived from'the separating column 94 likewise pass out of the fractionating column 8| through the line 82 to suitable condensers and gas separators, not shown.

A suitable pressure release valve 9'! is provided in the line 96 in the event that the separating column 94 is operated at a substantially higher pressure than that prevailing in the fractionating column 8|, since it is readily apparent that pressure in the latter may not exceed that prevailing in the coking chambers I3, 14 and 15 and will therefore ordinarily be not higher than 30 lbs. gauge, whereas the separating column 94 may be operated at pressures not exceeding those prevailing in the cracking chamber 9|, which may be substantially higher. The pressure in the separating column is preferably not higher than about 65 lbs. gauge.

In order to secure the desired cooling action in the fractionating column BI and the separating column 94, cooling coils 98 and 99 respectively may be provided therein, and the heat abstracted thereby may be utilized in preheating the crude. Crude or mixed oil is supplied to the heating tank 5|, to be fed to the heating or distilling coil 55. For instance, the crude oil or other oil fed to the system may be passed through line I60 to the coil 98 in the fractionating column 8| thence through line to the coil 99 in the separating column 94; and from the latter through the line 50 to the feed tank Although the present invention is described in connection with specific details of various embodiments thereof, it is not intended that these shall be regarded as limitations upon the scope of the invention, except in so far as included in the accompanying claims.

I claim:

l. The method of treating crude oil which comprises heating said oil to a temperature sufficient to vaporize a portion thereof and leave unvaporized a residue having a gravity of 27 A. P. I., or lower, dephlegmating resulting vapors in a first fractionating zone to produce a condensate, heating said residue to a cracking temperature under low pressure and introducing it into a coking zone wherein separation of vapors occurs, dephlegmating these vapors in a second fractionating zone and separating therefrom a heavy condensate in quantities only great enough to remove entrained tar, and a larger quantity of intermediate condensate, withdrawing said heavy condensate from said second fractionating zone and combining it with said residue for heating, mixing said condensate first-mentioned with said intermediate condensate, cracking the mixture in the vapor phase, under a pressure materially higher than said low pressure, dephlegmating the resulting vapors to separate a condensate, combining the separated condensate with said residue prior to the heating thereof to cracking temperature, combining the dephlegmated vapors with the vapors from the coking operation to be further de phlegmated therewith, and removing uncondensed dephlegmated vapors and condensing them as a desired product.

2. The method of treating heavy residual hydrocarbon oil which comprises heating said oil to a coking temperature, introducing the heated oil into a coking zone wherein coking occurs and vapors are liberated, fractionating said vapors to separate therefrom substantially only the entrained tar, further fractionating the vapors to separate condensate heavier than the desired final product as an intermediate fraction, cracking said intermediate fraction in the vapor phase, separating the resulting cracked products into vapors and a residue while out of contact with said vapors undergoing fractionation and in a zone separate from said coking zone, combining the vapors separated from said resulting cracked products with said vapors first-mentioned after removal of entrained tar, combining said entrained tar and said residue with said heavy residual oil and condensing the completely fractionated vapors as a desired final product.

ROBERT F. RU'I'HRUFF.

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