US2099907A - Distillation of hydrocarbon oils - Google Patents

Description

Nov. 23, 1937. M. c. ROGERS DISTILLATION OF HYDROCARBON OILS Filed Dec. 20, 1955 8 3 mm E235. l w? y me NT Q a a mmw 335 g 25.0w A MN 9 Q MQPQZQFQ'SKm INVENTOR "ARV/N 0. ROGERS I BY ATTORNEY Patented Nov. 23, 1937 method is an tion effected with the aid of DISTILLATION or HIDROCARBQN OILS Marvin 0. Rogers, Chicago, Ill., assignor to StandardO and more especially maximum quantities of coke and gasoline as valuable by-products. The expression clean pressure still charging stock is intended tion of objectionable coke.

Various methods have been employed in the production of reasonably clean charging stock from the heavier portions of crude oil. One

costs being very high. Another method is a non-cracking distillasteam or vacuum heavy bottom as otherwise a rather dirty chargcharging stock.

In carrying out charging stock and gasoline. In accordance with my inresiduum enables an operator to may be the last composition. The

il Company (Indiana), Chicago, 111., a corporation of Indiana Application December 20, 1933, Serial No.

shortening the length of any particular run by the clogging up of the heating coil. My invention permits of an increase in heat supply to the residuum before it enters the coking zone which is' not now possible or practical in commonly used methods. The increase in heat supplied to the not only obtain a maximum yield of pressure still charging stock of the desired cleanliness from the residuum but to also improve the quality of the coke and gasoline produced in the process as valuable byproducts.

My invention will be clearly understood from the following description in conjunction with the accompanying drawing which illustrates a diagrammatic view of apparatus suitable for carrying out the invention.

Referring to the accompanying drawing, the numeral I indicates a source of supply of hot petroleum residue for carrying out my process. The source of supply of hot petroleum residue of a series of continuous stills or may be the flash drum of a pipe still or other convenient sources of hot heavy residue from crude oil. This residue should preferably be of the type subjected to but little cracking or dehot residue may be withdrawn through a line 2 by means of a pump 3 and forced through a line 4 to a heating coil 6 positioned in a suitable furnace 5, the heat for which is preferably supplied by radiation from the products of combustion produced by a suitable burner or burners 1. If difficulty is experienced in pumping the hot residue from the source of supply I to the heating coil 6, a cooler (not shown) may be provided before the oil reaches the pump 3 in order to slightly reduce its temperature to a point where satisfactory pumping may be effected.

The petroleum residue passing through the to a suitable coking temheating coil 6 is raised perature therein and passed through a valved transfer line 8 to a manifold 9 having a plurality of valve pipes ll connecting it with an enlarged coking chamber l2, which may be suitably insulated against loss of heat. The coking chamber I2 is preferably vertical and of substantial dimensions and is adapted to contain the heated residue while distillation to coke takes place. The coking chamber l2 may be provided at its upper end with a valved pipe I 3 which opens to the atmosphere. Vaporous constituents evolved in the coking chamber I2 rise upwardly therein and are conducted by means of a valved line I 4 into the base of a suitable fractionating column IS. The

.tionating column l5 distillate receiver l9 by means of a pipe E8, the

distillate receiver having a valved gas outlet 2! at its upper end and a valved liquid drawoff line 22 at its bottom.

Only one coking chamber l2 has been illustrated for carrying out my invention. It is to be clearly understood that several of these 'cham- I bers may be used, preferably three in number. 8 may enter any selected one of these chambers through Suitable manifolds and connecting pipes similar to those shown. The manifolds may be connected to the line 8 and heated residue caused to flow to the selected coking chamber by manipulation of suitable valves. The use of several chambers enables the process to be carried out for a long period by changing the flow to the next chamber when one has been filled with coke.

The coking chamber l2 may be provided at its top with a valved pipe 23 which may extend to a suitable manifold, not shown, which connects with each of the manifolds associated with the coking chambers. By this arrangement, vapors from the coking chamber l2, or a part of the vapors may be passed through anotherempty chamber thereby preheating it for the reception of heated residue to be distilled to coke. The vapors after passing through the coking chamber next to be used may be passed through the line H to the bottom of the fractionating column l5. No claim is made to the method of preheating the coking chamber next to be used as it is described and claimed in the application of Ernest W. Thiele, Serial No. 332,541, filed January 14, 1929, now U. S. Patent 1,947,319.

As is clearly shown in the drawing, the valved pipes ll associated with the coking chamber l2 permit the residue to enter the chamber at various levels. The lowest pipe may be so placed as to cause the residue to enter the coking chamber l2 at the base thereof.

The coking chamber 12 is preferably mounted in an elevated position on any suitable supporting structure and is provided with a removable closure 24. The closure 24 permits entry into the coking chamber for the purpose of removing coke residue therefrom. If desired, a suitable pipe may be provided through the closure member 24 for the purpose of admitting any desired fluid into the lower part of the coking chamber.

In the lower portion of the tower IS the heavy entrained tar-like constituents are separated from the vapors by subjecting the latter to a slight condensation. A valved line 25 extends from the base of the fractionating column l5 and may be provided with a pump 26 for the purpose of withdrawing such separated heavy material together with the small amount of heavy condensate admixed therewith. The thus withdrawn material may be passed through branch conduits 21 and/ or 28 connecting with the outlet and inlet, respectively, of the heating co'l 6. In this manner the heaviest material is returned to the coking chamber l2 wherein it is further decompotigd.

The fractionating column l5 may be provided with a suitable drawoif line 29, positioned at a sired somewhat elevated point, for the purpose of withdrawing the clean charging stock produced in accordance with this process and which is separated in tower l5 as reflux condensate. As shown in the drawing, the valve line 29 may be positioned so as to withdraw the clean charging stock from a point. above the second or third plate within the fractionating column.

In operating, the coking chamber l2 preferably should be preheated to a satisfactory temperature, for example 650 F., in order to prevent the heated residue entering it from cooling to a point below cracking temperature. The preheating of the coking chamber [2 may be accomplished in any suitable manner, such as'by passing steam or heated oil therethrough or by} combustion therein. After the chamber to be used for coking has been preheated to the desired temperature, the petroleum residue from the source of supply and at a temperature of about 720 F. is forced through the heating coil 6 at a rate sufficient to prevent excessive cracking or coke deposition therein. The residue in passing through the heating coil may be raised to a temperature of about 900 to 910 F. or to such a high temperature that coking thereof may be accomplished in the coking chamber [2 by its contained heat. If dea. small quantity of steam may be forced into the oil to speed its flow through all or a part of the heating coil and minimize cracking conditions therein. The temperature to which the heavy residue is raised in passing through the heating coil may be varied depending upon the heavy residue being treated. For example, for a heavy residue from Mid-Continent crude, the

temperature thereof should preferably be above about 870 F. to insure the production of a satisfactory coke without too much volatile matter.

superior quality areobtained, together with a maximum yield of clean charging stock. While it is possible to raise the residue'to the desired high temperature in the heating coil, it is not practical or economical to do so in view of the adverse coke difficulties always experienced. In accordance with my invention, be supplied with additional heat before entering the disadvantages heretofore present. additional heating of the residue by admittingto the stream thereof, preferably after leaving the heating coil, a regulated quantity of an oxidizing fluid, such as air or other combustion supporting or oxidizing material, to thus raise the temperature of the residue to that desired in its passage through the pipes connecting the heating coil and the coking chamber. As shown the drawing, a regulated quantity of air or other the residue may,

suitable fluid, preheated if desired, may be forced introduction of the air may be to arrange the nozzle tangentially to the transfer line 8.

The air entering the stream of 011 residue consumes a very small quantity of it in supplying the additional heat required to raise the temperature of the stream entering the-coking chamber to that desired. ature of the oil leaving the heating coil may be raised from 900 F. to 940 F. before entering the coking chamber by adding 160 cubic feet of air at 60 F. per barrel of charge of 50 gallons each.

' pipe II as long as possible in order to accomplish the desired building up of the coke from the bottom. If the lowest pipe II heated stream of residue may then be introduced into the next higher pipe I I. By building up the coke in this manner, it is possible to obtain the production of a much denser coke than would be possible if the heated residue was only supplied at one point.

The vapors from the coking chamber entering the fractionating column l5 are therein fractionated to yield an overhead gasoline or pressure distillate which is condensed and collected in the distillate receiver I 9. Clean cracking stock is withdrawn through the pipe 29 and the reflux below the lowest two or three plates, which is not sufficiently clean to be raised to a high cracking temperature in that it consists mainly of heavy entrained matter separated from the vapors, is preferably returned by the pipe 25 to the inlet and/or outlet of the heating coil 6.

In operating in accordance. with my invention it is preferred to maintain the coking chamber l2 at approximately atmospheric pressure. In operating in this manner only suflicient pressure is applied by the pump 3 to force the petroleum residue through the heating coil 6 at the desired rate to prevent coke deposition therein. The destructive distillation taking place in the coking chamber may, if desired, be effected at moderately superatmospheric pressure of between 20 to 30 pounds per square inch. I i

In coking petroleum residues from Mid-Continent crude temperatures between about 870 F. and about 940 F. have been employed. My invention contemplates raising the particular pe-- troleum residue being treated to a temperature Just below that at which objectionable coke deposition takes place in the heating coil and thereafter supplying additional heat to the thus heated residue to raise it to a higher temperature. For example, the oil in passing through the heating coil may be raised to a temperature of about 920 F. and thereafter supplied with additional heat to cause the temperature to be raised to about 960. F.

It has been found that the coke and gasoline obtained when additional heat is supplied in accordance with my invention possessessuperior qualities to those obtained when additional heat is not supplied. The oxidized gasoline obtained is much more stable than finished cracked gasoline as begins to clog, the

regards oxidation stability and it has been found that as little as 2 of oxi d duced in accordance with my invention when mixed with finished gasoline to be more stable than the finished gasoline alone. 5 Moreover, it has been found that the octane number of the gasolineobtained inaecordance with my process was better Without supplying additional eration, 10% of lump coke (as determined by a screen of three inch square mesh) was obtained.

ized gasoline procauses the mixture than that obtained heat by oxidation. The addition of air can be accomplished with- 10 out any harmful effect to the transfer line or air nozzle whereas heretofore hot spots or the like were likely to occur when This is particularly, true when air is introduced into an enlarged coking chamber, the difliculty' 15 residing in the lack of combustion within the chamber and the inability to accomplish even distribution of the air throughout the body of air was introduced.

positive indications of oil residue being coked. Coke obtained in accordance with my inven-' 20 tion has been found to be harder than that obtained when-operating introduction of a controlled quantity of air. The

the process without the greater percentage of lumps than was possible 25 While myinvention has been described as cok- 30 ing uncracked petroleum residue obtained from the distillation of crude oil, it is to be understood that such a residue mixed with pressure tar ob tained from a cracking operation may alsobe coked. The pressure tar may be introduced into the stream of petroleum residue passing through the line 4 by means of a sired, the pressure tar petroleum residue in the source of supply I and the mixture forced through the heating coil as 40 described. When pressure tar is mixed with the petroleum residue, it has been found that more advantageous results are obtained when a small quantity of the pressure tar is used. For example, about 7 to 10% mixed with the petroleum residue to obtain the desired valuable by-products as well as the desired maximum yield of clean charging stock.

valved pipe 32. If demay be mixed with the I of pressure tar may be 45 Obviously, many modifications in the appa- What I claim is: s

1. A method of converting heavy residual hy- 55 drocarbon oil into lower boiling hydrocarbons and a solid coke residue, which comprises passing heavy residual hydrocarbon oil in a confined stream through a heating zone, heating said oil during passage through temperature, controlling the rate of flow of said oil through said zone and time of treatment therein to avoid troublesome coke deposits within said heating zone, thereafter introducing a gas containing free oxygen into said stream of heated 65 oil to effect partial combustion of said oil to further increase the temperature thereof, limiting the amount of gas containing free oxygen added to said heated oil to thereof from rising more than about 40 F. above 70 that obtained in the heating coil and maintaining said oil thus heated in a coking zone for a period adequate to convert said oil into a solid coke residue and lower boiling hydrocarbons.

said zone to a cracking 60 prevent the temperature 2. A methodof converting heavy residual hy- 75 therein to avoid troublesome 4 drocarbon oil into lower boiling hydrocarbons and a solid coke residue, which comprises passing heavy residual hydrocarbon oil in a confined stream through a heating zone, heating said oil during passage through said zone to a cracking temperature, controlling the rate of flow of said oil through said zone and time of treatment coke deposits within said heating zone, thereafter introducing a gas containing free oxygen into said stream of heated oil to effect partial combustion of said oil to further increase the temperature thereof, limiting the amount of gas containing free oxygen added to said heated oil to prevent the temperaturethereof from rising more than about 40 F. above that obtained in the heating coil, thereafter passing said heated oil into an enlarged coking chamber, maintaining said oil within said coking chamber for a period adequate to convert said oil into a solid coke residue and hydrocarbons boiling below said heavy residual oil.

' 3. A method of processing heavy hydrocarbon oil to produce gasoline which comprises passin a confined stream through a tubular heating said oil during its passage said oil in heating I coil,

of the oil within said coil with respect to each other to effect the maximum cracking of the oil within the coil while avoiding troublesome coke deposits therein, passing the converted products from said heating coil into a reaction zone wherein further conversion is effected and vapors separate from residue, introducing air into the cracked products from said tubular heating coil in an amount of about 3.2 cubic feet of air at F. for each gallon of oil treated to further heat said oil by partial combustion thereoflto a temperature not more than about 40 F. above that obtained in the heating coil, separately removing the vapors from saidreaction zone and subjecting them to fractionation to separate a gasoline distillate fraction relatively free of. gumforming constituents.

MARVIN C. ROGERS.

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