US2005527A - Treatment of hydrocarbon oils - Google Patents

Description

June 18, 1935. J. G. ALTHER TREATMENT OF HYDROCARB ON OILS Filed Dec.

INVENTOR JOSEPH G. ALTHER F OZEW ATTOR N Patented June 18, 1935 UNITED STATES TREATMENT HYDROCARBON OILS Joseph 'G. Alther, Chicago, Ill., assignor to Universal Oil Products Company,

Chicago, 111., a

corporation of South Dakota Application December 19, 1931, Serial No. 582,020

Claims.

This invention relates to the treatment of hydrocarbon oils, and refers more particularly to the refining of crude petroleums to produce maximum yields of desired products such as gasoline 5 and lubricating oils with minimum losses.

More specifically the invention has reference to a particular combination of refining operations involving the topping of crude oil to remove gasoline and other light fractions. the cracking of portions of the crude oil and the production of high yields of lubricating oils and of gasoline having a high anti-knock value.

In one specific embodiment the invention comprises heating crude oils by heat obtained by indirect contact with vapors from a secondary fractionator, fractionating' the heated crude in a primary fractionator to produce residuum and light overhead stocks which are cooled, condensed and collected, subjecting ,the light overhead fractions to conversion conditions of temperature and pressure along with refluxes from a final fractionator, passing the heated products to an enlarged vaporizing and reaction zone, introducing topped crude from the primary fractionator into the reaction zone, totally discharging the. products from the reaction zone, fractionating said products under a reduced pressure in a secondary fractionator to produce a heavy residuum which is removed from the system, a

plurality of lubricating side cuts, and overheadvapors containing substantial amounts of gasoline boiling range fractions, passing the overhead vapors in indirect heat exchange relation with incoming crude oil and fractionating said vapors thereafter in a final fractionator to produce vapors of approximate gasoline boiling point range which are cooled, condensed and collected and intermediate insuificiently converted refiuxes which are returned to the heating zone for further conversion.

To further clarify and explain the invention, the attached drawing is referred to which shows by the use of conventional figures in side elevation one form of apparatus suitable for the operation of the process of the invention.

Referring to the drawing, crude petroleum of any type is preferably introduced into the system by way of a line 9, containing control valve 2, and pumped by a pump 3 through a line i, con.- taining control valve 5, through a heat exchanger 6 in which it absorbs a certain degree of heat from the overhead vapors from a secondary fractionator as will be presently described. lhe heated crude may then pass through a line i, containing a control valve 8, and enter a primary topping column 9, wherein such light overhead fractions are distilled as are possible of distillation at the temperature attained as a result of the heat exchange mentioned.

Overhead vapors may be conducted through vapor line l0, containing control valve, II, and be partially liquefied by condenser l2, liquid condensates and fixed gases then passing together through a line I3, containing a control valve It, to a receiver IS in which separation of liquids and gases is effected. This receiver may be provided with gas release line I6, containing a control valve ll, through which gases may be released at a rate consistent with the maintenance of suitable back pressures upon the preceding condenser .and fractionator. A draw line l8 containing a control valve I9, is preferably provided for removal to storage or use of such portions of the straight run gasoline fractions as are not required at succeeding stages in the process.

The major portion of the light distillates from the topped crude which may comprise substantially all of the straight run gasoline and under certain conditions of operation a large percentage of the kerosene fractions is subjected to a cracking operation. To this end a pump 22 preferably ransfers these fractions to a heated conversion zone by taking suction through line 20, containing control valve 2|, and discharging them through a line 23, containing control valve 24, through a heating element 30 disposed to receive a proper amount of heat generated in a furnace setting 3 I Prior to entering the heating element intermediate refluxes preferably enter line 23 from line 63 as will be later more fully described.

A consideration of the wide variations in both quality and quantity of the combined feed which may enter the heating zone will show that any statements as to the exact amount of heating and the pressure employed in the heating and reaction zones will be necessarily subject to reservations and a designation of the operating range of temperature or pressure is diflicult. However, practical considerations of reaction velocity will usually fix the minimum temperature at approximately 850 F. in the case of the type of fractions it is intended to heat and the upper limit will be fixed more or less by the question of strength of -materials, extensive experiments having shown that temperatures much above 1000 to 1050 F. are frequently dangerous. Thus, it may be stated that temperature limits are usually comprised within the range of 850 to 1050 F.

The optimum pressure for any given case will likewise be fixed by a consideration of the type of combined feed undergoing conversion, its volatility and the amount of conversion desired as well as its influence upon subsequent operations. When the crude processed, for example, contains large amounts of straight run gasoline of relatively poor anti-knock value, the pressure may be raised to a considerable point, possibly 500 pounds per' square inch, to provide a relatively long time factor and insure re-formation to produce improved anti-knock value. Sinceit is 2. intended that the heat added to the system for both conversion and fractionating operations is to come from but one heating zone, and since the flow into transfer line 32 through valve 29, con-.

tained in line 28. The temperature in reaction zone 34 will necessarily reach an intermediate point which is the resultant of the heat exchange between the conversion products from coil 30 and the topped crude.

It is the intent of the invention to heat the topped crude in chamber 34 only to a temperature at which it will be lightly cracked, under which conditions there will be a minimum decomposition of the natural lubricating oil fractions remaining in the topped crude after the preliminary removal of gasoline, kerosene, et cetera. In the majority of cases the maximum temperature obtained in reaction chamber 34 will generally not exceed 850 F., and in many instances will be much lower.

The reaction products from chamber 34, both liquid and vaporous, are preferably totally discharged through a line 31, containing a control valve 38, into a secondary fractionator 39 which is preferably operated at pressure very considerably lower than those obtaining in the heating and reaction zones. The operation of this fractionator constitutes a special feature of the invention and therefore warrants detailed descrip-- tion.

This fractionator is primarily operated to produce a plurality of lubricating oil stocks as side cuts, there being drawn from the bottom of the tower a residuum too heavy to contain any lubricating stocks of value and not suitable for further processing or for further heat treatment on account of its coke-forming tendencies. As an overhead product from this tower, gasoline and fractions intermediate between gasoline and the lightest lubricating stock desired are produced. Lines 42, 42 and 42" containing valves 43, 43' and 43", respectively, have been shown to represent any number of lines through which lubricating stocks of varying viscosity may be withdrawn at different elevations in the tower, these being cooled and run to storage though coolers and lines are not shown in the drawing. Heavy residuum is preferably withdrawn from the bottom of the tower thru a line 40, containing control valve 4|, and the overhead fractions leave through a vapor line 45, containing control valve 46, to impart a portion of their contained heat to the incoming crude oil as has been already described. In a majority of cases it is necessaryto introduce steam into the fractionator to assist in the non-cracking distillation of the lubricating cuts by its carrying action, such steam, either saturated or superheated as occasion demands, being introduced through a line 44', containing a valve 45', and terminating in a spray or other distributing means 46'. To further assist in controlling the fractionation and boiling range of the overhead fractions a coil 44 may be provided in the top of the fractionator through which cooling fluid may be pumped in controlled amounts as indicated by the arrows.

Cooled and partially condensed vapors from heat exchanger 6 may be conducted through a line 41, containing a control valve 48, to a final fractionator 49, in which conditions are-maintained to produce overhead vapors of a substantially gasoline boiling point range and intermediate refluxes which are returned to the heating zone for further conversion. Gasoline vapors may be conducted through a vapor line 50, containing a control valve 5|, and pass through a condenser 52 which serves to liquefy the gasoline fractions, the gasoline and fixed gases then flowing through a line 53, containing a control valve 54 to a receiver 55, in which their separation is effected, the gases being released through a line 56, containing a control valve 51, and the gasoline being withdrawn to storage through a line 58, containing control valve 59.

Refluxes from final fractionator 49 are passed through a line 60 containing a control valve 6|, to a pump 62 which discharges them through a line 63, containing control valve 64, to the heating and conversion zone of the process.

Inasmuch as the-heat input in the process is dependent upon the heating of an intermediate distillate, it will be appreciated that at the beginning of a run a suitable distillate from an extraneous source can be initially utilized to charge the heating coil, such extraneous supply being discontinued as soon as the plant is on stream.

An auxiliary inlet line I, containing a valve 2', is shown to indicate that in some cases crude oils of particular characteristics may be introduced directly into transfer line 32 by way of pump 21 without preliminary heating in heat exchanger 6.

A typical example of operations and results obtainable therefrom will serve to illustrate the features of the process and show its commercial value. Such an example may be one in which a crude oil from 'the Bardsdale Field in Ventura County, California, is processed. The gravity of such a crude may be 30.5 A. P. I. and it may have a sulfur content of 0.83% and a pour test of 25 F. The following yields of products may be produced by the more generally used methods of refining involving primary atmospheric pressure distillation to remove gasoline, kerosene and gas oil fractions, followed by reduced or subatmospheric pressure distillation to remove lubricating oil fractions and produce a light asphaltic residuum:

Per cent of A. P. I.

Product crude The straight run gasoline produced by the above operation may have an anti-knock value expressed as octane number of 50-55, this representing the total yield of gasoline by non-cracking operations. The residuum shown may have use as fuel oil or light road oil or may be reduced to asphaltic consistency by further reduction for the production of overhead stocks capable of being worked up into cylinder oils.

By running this same crude through a combination of operations similar to that described with reference to the drawing, the net results may be, under properly controlled conditions such'as temperature of 950 F. in the transfer line and 850 F. in the reaction chamber along with a pressure of; 30!) pounds-per square inch, a substantial reforming of the straight run gasoline and a selected-cracking of the kerosene and gas oil fractions and the easily decomposable residuum, so that the improved yields from the standpoint of motor fuel and lubricating oil fractions will be as follows:

Percent of A. P. I. Product crude gravity 419 end point gasoline 55 53. Light gas oil or recycled stock 32 Light lubricating stock (150 sec. Saybolt) 9 27. 5 Medium lubricating stock (325 sec. Saybolt 7 23. 2 Heavy lubricating stock (450 sec. Saybolt). 2 20. 8 Fuel oil residuum l2 5 A comparison of the yields by ordinary and by the improved operation characteristic of the present invention will show that the gasoline yield has been increased approximately 30% on a crude basis and that the total yield of light, medium and heavy lubricating stocks has been reduced slightly, this reduction being more than compensated by the fact that they are more resistant to the deteriorating influence of high temperature usage. The gasoline produced by the improved operation will be that resulting from the re-forming of the natural gasoline, the cracking of intermediate straight run cuts under conditions of proper severity and mild cracking of the light asphaltic residuum, .this mixed gasoline having an octane number in the neighborhood of 75, which conforms to the demands of the best premium gasolines. In addition, to those skilled in petroleum refining operations, the process presents the advantage of simplicity and heat conservation, both of which are desirable from an economical standpoint.

The invention as described above by the specification and example given is generally broad in scope and applicable to practically any type of crude oil with suitable modifications of equipment and operating conditions, so that the particular description of apparatus and the results obtained in one instance are neither to be construed as imposing limitations thereon.

I claim as my invention:

1. A process for treating crude petroleum oil containing natural gasoline which comprises topping the crude and separating therefrom a distillate containing a substantial quantity of the natural gasoline hydrocarbons, combining said distillate with a hydrocarbon distillate heavier than gasoline formed as hereinafter set forth, passing the resultant mixture through a heating zone and heating the same therein to cracking temperature under pressure, commingling the topped crude with the heated mixture discharging from the heating zone, separating the thus commingled oils into vapors and residue, fractionating the vapors and separating therefrom a reflux condensate heavier than gasoline, utilizing such reflux condensate as said hydrocarbon distillate heavier than gasoline, and condensing and collecting the fractionated vapors.

2. A process for treating crude petroleum oil containing natural gasoline which comprisestopping the crude and separating therefrom a distillate containing a substantial quantity of the natural gasoline hydrocarbons, combining said distillate with a hydrocarbon distillate heavier than gasoline formed as hereinafter set forth, passing the resultant mixture through a heating zone and heating the same therein to cracking temperature under pressure, commingling the topped crude with the heated mixture discharging from the heating zone under conditions such, as will not destroy the lubricating oil components of the crude, separating the thus commingled oils into vapors and residue, subjecting the vapors to primary fractionation to condense and separate lubricating oil fractions therefrom, withdrawing such condensed lubrieating oil fractions and recovering the same as a product of the process, further fractionating the vapors to condense fractions thereof intermediate gasoline and lubricating oil and utilizing resultant reflux condensate as said hydrocarbon distillate heavier than gasoline, and condensing and collecting the fractionated vapors.

3. A process for treating crude petroleum oil containing natural gasoline which comprises topping the crude and separating therefrom a distillate containing a substantial quantity of the natural gasoline hydrocarbons, passing said distillate through a heating zone and heating the same therein sufficiently to increase the antiknock value of the gasoline hydrocarbons contained therein, commingling the topped crude with the hot distillate discharged from the heating zone whereby the topped crude is raised to cracking temperature by the heat of the distillate, separating the commingled oils into vapors and residue, and fractionating and condensing the vapors.

4. A process for treating crude petroleum 011 containing natural gasoline which comprises topping the crude and separating therefrom a distillate containing a substantial quantity of the natural gasoline hydrocarbons, passing said distillate through a heating zone and heating the same therein sufficiently to increase the antiknock value of the gasoline hydrocarbons contained therein, discharging the heated distillate into an enlarged reaction zone maintained under cracking conditions of temperature and pressure, introducing the topped crude into said reaction zone and commingling the same therein with the heated distillate, separating the commingled oils into vapors and residue and fractionating the former to condense heavier fractions thereof, heating resultant reflux condensate to cracking temperature and pressure and thence introducing the same to the reaction zone, and finally condensing the fractionated vapors.

5. A process for treating crude petroleum oil containing natural gasoline which comprises topping the crude and separating therefrom a distillate containing a substantial quantity of the natural gasoline hydrocarbons, heating said distillate, while flowing in a restricted stream under pressure through a heating zone, sufficiently to increase the anti-knock value of the gasoline hydrocarbons contained therein and then discharging the same into an enlarged zone, introducing the topped crude into said enlarged zone to be heated therein by contact with the heated distillate and separating the resultant mixture into vapors and residue, fractionating the resultant vapors to condense heavier fractions thereof, heating resultant reflux condensate to cracking temperature under pressure and then discharging the same into said enlarged zone and finally condensing the fractionated vapors.

JOSEPH G. ALTHER.

DISCLAIMER '2,005,527.Joseph G. Alther, Chicag Patent dated June 18, 1935. the assignee, Universal Oil 0, ]]l. TREATMENT OF HYDROCARBON Oms. Disclaimer filed June 29, 1938, by the patentee;

Products Company, approving and concurring.-

Hereby enters'this disclaimer to claims 3, 4, and 5 of the patent.

[Oflicvlal Gazette July 26, 1938.]

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