US1473316A - Process of producing low-boiling oils - Google Patents

Description

a Nov. 6,1923.

G. L.'PRICHARD ET AL PROCESS OF PRODUCING LOW BOILING VOILS 3 Sheets-Sheet 1 Filed Nov. 19 1921 Nov. 6, 1923.. 1,473,316

G. L. PRICHAI QD ET AL PROCESS OF PRODUCING LOW BOILING OILS Filed Nov. 1 9. 1921 3 Sheets-Sheet 3 3 m II Nov. 6, 1923. j 1,473,316

G. L. PRICHARD ET AL I PROCESS OF PRODUCING LOW BOILING OILS Filed Nov. 19, 1921 3 ShegztS-Sheet 5 71 6:9

a g Q I zfi a; 22 j o I\ W W Patented Nov. 6, 1923.

UNITED STATES GEORGE L. PRICHARD AND HERBERT HENDERSON, 0]? PORT ARTHUR, TEXAS, AS

SIGNORS TO GULF REFINING COMPANY, OF PITTSBURGH, PENNSYLVANIA, A COR- PORATION OF TEXAS.

PROCESS OF PRODUCING LOW-BOILING OILS.

Application filed November 19, 1921. Serial No. 516,374.

To all whom it may concern:

Be it known that we, GEORGE L. PRICH-. ARD and HERBERT HENDERSON, citizens of the United States. and residents of Port Arthur, in the county of Jefferson and State of Texas, have invented certain new and useful Improvements in Processes of Producing Low-Boiling Oils, of which the following is a specification.

This invention relates to processes of producing low boiling oils; and it comprises a method of converting higher boiling petroleum hydrocarbons (such as gas oil or kerosene)into lower boiling hydrocarbons, (such as gasoline), wherein a boiling bath of a catalytic agent such as anhydrous aluminum chlorid or other metallic halid and higher boiling oil is established and maintained under standardized conditions of temperature and concentration, said bath being replenished with oil and chlorid to make up for vapors of oil withdrawn and exhausted chlorid removed, the heat necessary, for conversion and distillation being supplied to the bath in such manner as to avoid injury to the aluminum chlorid; allas more fully hereinafter set forth and as claimed.

As is now known, high boiling petroleum oils can be converted into lower boiling oils, such as'gasoline, by the action of anhydrous aluminum chlorid. Unlike oils produced by destructive distillation or cracking, these oils are of saturated and sweet nature. In so doing, the petroleum oil is boiled with a small proportion of chlorid, usually about five per cent, and the low boiling oils distilled away as fast as produced, using certain precautions in distillation to prevent aluminum chlorid passing forward with the distillate.

The reaction mixture enters into active ebullition at a temperature which may be,

the lower layer thickens and stifiens progressively and finally becomes of a coky or asphaltic consistency. These changes are reflected in the work of the stirring mechanism which at first moves readily, then begins to require much power and finally moves more easily again. With these changes comes also a progressive diminution in converting or catalyzing power; the aluminum chlorid becomes exhausted and in order to keep up the flow of distillate, it is necessary to raise the temperature. In practice it is found, however, that the rapidity of this diminution in activity depends to a considerable extent on the conditions of operation; that the number of gallons of oil which can be treated by a given charge of chlorid is much aflected by apparently small changes in heating and stirring conditions.

It is the object of the present invention to rearrange and standardize conditions so as to secure an even and uniform production of vapors of low boiling oils in continuous operation, irrespective of the age of the charge of chlorid in use, and to utilize the activity of the chlorid to the fullest extent. To this end, a boiling bath of chlorid and oil of standardized composition is established and maintained in a suitable reaction chamber, replenishing the oil by fresh supplies as oil disappears in the formation of removed vapors and supplying fresh active chlorid in proportion to the removal f the exhausted material. So far as is practicable, the heat required in the operation is supplied elsewhere.

Looked at in one way, the stated process is really one of distillation; the high boiling oil is brought to a certain temperature and then distilled away as vapors of low boiling oils. While the temperature required is not high, there must be an ample supply of heat. The amount of heat necessary is further increased by the practice of condensing and backtrapping a portion of the vapors to prevent aluminum chlorid going forward to the condenser. In the usual practice, using stills heated at the base, much or most of this relatively large amount of heat must be supplied through a layer of aluminum chlorid on the bottom of the still.

As already stated, the aluminum chlorid v melts down to a heavy viscid layer underlying the oil body and progressively becoming thicker in consistency. Whatever the efiiciency of the stirrer, the bottom of the still cannot be kept free of aluminum chloride and particularly in the later stages of operation. The aluminum chlorid composition ba'kes on. And such aluminum chlorid composition as is present on the bottom of the still or bakes thereon is overheated; it is heated to a temperature above that prevailing in the reaction zone proper. This uperheating of the aluminum chlorid composition rapidly destroys its activity For the stated reasons, in maintaining a standardized boiling bath in the reaction chamber, it is highly desirable that, so far as possible, all the heat be added elsewhere; that is, outside the chamber. In part the heat units necessary in the operation canbe supplied as heat of incoming oil; as superheat of the oil. With some oils, considerable vaporization is practicable in the preheating and these vapors afiord much heat to the bath in condensing therein. As a rule we do not desire in preheating and superheating to have such conditions of time and temperature as to cause much cracking. The reaction vessel itself may be heated to some extent; but it is advantageous to furnish as much ofthe heat as possible elsewhere. In furnishing the heat necessary, over and above that which is supplied as preheat, in the present invention there may be used a heating system employing superheated steam as a heating fluid. In so doing, the necessary heat units can be supplied without the use of temperature dangerous to the aluminum chlorid.

In the best embodiment of the present iiivention we use, a heat-insulated reaction vessel provided with means for supplying oil thereto, means for removing vapors therefrom, suitable backtrapping means to prevent aluminum chlorid going forward, and with means for supplying fresh chlorid and removing exhausted sludge. The incoming oil advantageously delivered below the normal oil level in the reaction vessel, is heated, prior to its entry into the reaction vessel, to as high a temperature as is practicable. For reasons stated, the formation of vapors in the preheating is not objectionable and is indeed desirable, in so far as it can be done without too much cracking. The reaction or converting chamber is further provided advantageously with interior heating means, such as a steam coil or the like.

In the described method of operation, the aluminum chlorid composition is not exposed to intense direct heat and its period of activity is made much longer; that is, a given amount of aluminum chlorid will suffice for the treatment of much more oil.

The aluminum chlorid is at no time exposed to a reater heat than that of the body of oil in w ich it occurs. And there is no formation of coked bodies or masses. When the-ac tivity of the aluminum chlorid is substantially spent, it occurs in a readily settling sludgy mass which gravitates to the bottom of the reaction vessel and since the fresh aluminum chlorid added continuously, or from time to time, stirs up with comparative readiness, this fact enables continuous operation. The settled material can be removed without substantially stopping the operation and the addition of fresh aluminum chlorid does not interfere with this removal.

In the accompanying drawings, showing one form of suitable apparatus for the performance of our process;

Fig. l is an elevation, partly in section,

showing the preheater, converter and still,

and condensers;

Fig. 2 is a top plan view of Fig. 1; v Fig. 3 is a vertical section on an enlarged scale through the converter and still, the air condenser being shown in elevation; and F Fig. 4 is a section along line 4c-4r of Referring to the drawings, 1 is a suitable foundation upon which is mounted the superstructure of the preheater. This consists of the walls 2 suitably lined with heat insulation 3 and fire bricks 4. The fire box 5 is provided with the oil and steam or other burner 6 and the bridge wall 7 for directing the gases into the furnace shaft. Mounted upon the walls 2 are the upright beams 8 I of angle iron or the like connected by thecross heads 9, the structure being suitably braced by the angle irons 10. The preheater is suspended from this superstructure by means of the suspension rods 11 attached to the ears 12 of the upper drum 13. This drum is provided with the angle irons 14 which, in turn, rest on the angle irons 15 suitably secured by rivets or the like to supports 8. The lower drum 16 is in communication with the upper drum through a plurality of tubes 19. In the furnace shaft is provided a plurality of bafiics 20 of fire brick or the like and near the top of such shaft is the flue 21 leading to the stack 22. The bottom of the furnace shaft may be provided with the depression 23 and the pipe line 24 for carrying off residual oil and the like to the receptacle 25. This inlet is to be used when the preheater is down for repairs or cleaning purposes and particularly when the tubes are being cleaned.

High boiling oil is admitted, to the lower drum 16 through the oil inlet 26 which may be provided with a thermometer 2? in order to record the temperature of the incoming oil, whereby the efliciency of the heating unit may be determined. The high boiling oil heated in the tubes 19 goes to thedrum 13, from which it is delivered by means of the pipe 28 to the converting apparatus. This pipe 28 is insulated with asbestos or the like 29 and may be provided with a thermostat control, shown diagrammatically at 30, which may govern the amount of fuel oil or gas fed to the burner 6. When the temperature of the oil leaving the preheater is too high, this thermostat control will automatically close the valve on the oil or gas line and when the temperature of the oil leaving the heater is too low, it will open this valve. This is a standard equipment and the details are not shown.

The converter and still 31 is mounted.

upon supports 32 and is providedwith the inlet 33 which may be a continuation of the p1pe 28. To the inlet 33 is connected the pipe 34 which delivers hot oil to the cross a point near the bottom of the converter and still. The inlet 33 is located at a point near the bottom of the converter and still. The converter and still is provided with a plurality of petcocks 38, suitably valved (valves not shown), for determining the level of the contents of the apparatus. The converter may be made of steel or other material 39, suitably heat-insulated with asbestos, sil-ocel or' the like, 40, and it is provided advanta ously near the top with the'inlet 41, for de ivering a magma of aluminum chlorid and oil. This ma ma is preferably delivered below the level 0 the aluminum chlorid and oil in the converter, as is shown bythe down pipe 42. Mounted on the converter or still are the brackets 43 carrying the journal 44 through which passes the shaft 45 carrying the beveled gear 46, meshin with pinion 4 carried by sprocket whee 48, driven by chain 49, leading to reduction gearin 50 suitably driven by belt or chain 51 ro n motor 52. The stirrer shaft 45 carries a plurality of stirrers 53 very much like propeller blades adapted to thoroughly stir or churn the contents of the still. These may be mounted on collars 54 suitably keyed to the shaft and some of the stirrers may be longer than the others to insure uniform and thorough mixing. The stirrer arms 53 carry sets of chains 55 to assist in the stirring and to scrub the walls. The shaft at the bottom is suitably journaled as at 56, such journal being supported by the brackets 57. The still may be heated by steam entering the coil 58 through inlet 59 and withdrawn through 60. The cone-sha ed bottom or settling basin 61 of the stil and converter is provided with the draw-oif line62 for the contents of the still or for drawing off the residual oil and aluminum chlorid or 67 leading to the line 68 carrying condensates back to the still and converter, advantageously under the level of the contents thereof. From the second air cooled contrapped connection 74. This trapped con- J nection forms a seal so that any gases may pass through the line 75, while the liquid low boiling oil condensed may pass to the storage stock tanks through line 76. a

The steam for coils 58 in the converter and still may be superheated in the superheater 77..

In a specific embodiment of our invention, gas oil or other higher boiling h drocarbon oil is pumped to the preheater t rou h the valved inlet 26 and is heated to ahig temperature. In the case of gas oil, for example, the temperature may go anywhere from 500 to 700 F., while in the case of kerosene, the temperature may be somewhat less, say, from 450 to 600 F., or more. Stack gases find exit through the flue 21 and thence to stack 22. v

The higher boiling oil preheated in the preheater is delivered by means of the heatinsulated pipe 28' to the bottom of the still and converter 31, which may now be supplied or ,which may previousl supplied with a charge of alumlnum chlorid and oil from mixing apparatus (not shown) The stirring mechanism of the converter and still is set in motion and steam under preshave been sure and at high temperature is admitted tothe heating coil 58, so that the mixture of higher boiling oil and aluminum chlorid in the still or converter is kept at boiling temrature. The vapors of produced lower oiling oil asoline) together with vapors of higher boi ing oil, aluminum chlorid and combinations of aluminum chlorid with the oil, pass to the preliminary cooler 64, where the majorityof the hi h boiling oil, together with aluminum chlorid and its combinations with the oil, are condensed and are conducted back to the still or converter by the trap line 68 to the still.

line 68. The lighter vapors flow on to the second condenser 66, where condensates are returned by means of the line 67 and back- Vapors leaving condenser 66 go to the final water cooled condenser 70.

In operation, the still and converter should be run at such a rate that at no time the volume of the vapors in the second air cooled condenser 66 or in the pipe leading therefrom shall be such as to maintain the thermometer 71 at a temperature higher than about 350 F., since at about that temperature and much above, the aluminum chlorid and its combinations with the oil are in vapor form and would leave the system with the vapors of the lower boiling oils produced.

Cracking is not particularly harmiful, since the vapors and the oil from the preheater will both go to the converter and be converted into saturated-products. The time factor enters into cracking and since the high boiling oil is constantly moving in the preheater not much cracking takes place, even at relatively high temperatures. It is therefore possible to use relatively high temperature in the preheater. The higher the temperature in the preheater or the greater the amount of vapors delivered to the converter, the less the amount is necessary in the converter itself.

The mixture in the converter and still is heated to the boiling temperature,'which of course depends upon the character of the higher boiling oil undergoing treatment and the percentage of aluminum chlorid in the converter. With gas oil boiling around 600 F. and with 5 per cent of aluminum chlorid in the converter, to cause boiling it is necessary to heat the mixture to a temperature of from, 500 to 550 F.

The stirring mechanism in the converter should be operated at a speed sufiiciently high to thoroughly mix the aluminum chlorid and the oil inthe converter.

While the process may be run as a batch process. we prefer to operate continuously, supplying in proper ratio the aluminum chlorid in admixture; with enough oil to make it fluid through inlet 41 and the higher boiling oil from the preheater through in et 33.

After a time, the aluminum chlorid and its combinations with the oil form a heavy residue containing more or less coke which settles in the conical-shaped bottom 61 of the converter and such residue may be withdrawn by means of the outlet 62 and sent to suitable recovery apparatus. This residue, which is termed sludge. contains very little free oil, since the sludge settles in the coned bottom of the converter.

We are aware that it has been proposed to heat the high boiling oil for the purpose of drying it before adding to the still containing the aluminum chlorid, but it is our purpose to do more than this and superheat the incoming oil to a relatively high temperature and in effect use it for supplying substantial quantities of heat units to the converter and still.

While aluminum chlorid in anhydrous form is the best catalytic agent for the purpose now known to us, other catalytic agents may be used, such for instance as other metallic halids-ferric chlorid and zinc chlorid; but they are not so active as aluminum chlorid.

lVhile the preheated oil supplied to the converter is advantageously of the same general character as that already contained therein, it is not necessarily so; as it is frequently convenient to change the supply of oil from onegrade to another in continuous operation; and futhermore, in any event, the oil of the bath is always composed in part of refluxed oils coming from the backtrapping means, and therefore may differ somewhat from admitted oil.

We claim:

1. The process of converting hi her boiling oils into lower boiling oils w ich comprises establishing and maintaining a boiling body of higher boiling oil and aluminum chlorid, conducting vapors of lower boiling oils formed away from such body,

and supplying additional high boiling oil substantially in liquid form; to said body at a temperature higher than the boiling point of the body.

2. The process of converting higher boiling oils into lower boiling oils which comprises establishing and maintaining a boiling body of higher boiling oil and aluminum chlorid. conducting away from such body vapors of lower boiling oils formed, supplying additional higher boiling oil substantia'ly in liquid form at a temperature higher than said body and supplying heat directly to said body of higher boiling oil and aluminum chlorid.

3. The process of converting higher boiling oils into lower boiling oils which comprises establishing and maintaining a boil-- ing body of higher boiling oil and aluminum chlorid, conducting away from such body vapors of lower boiling oils formed, supplying additional higher boiling oil substantially in liquid form at a temperature higher than said body and supplying heat directly to said body of higher boi ing oil and aluminum chlorid, said heat being supplied at a temperature not much above that of said body. 0

4. The process of converting higher boiling oils into lower boiling oils which comprises establishing and maintaining a boiling body of higher boiling oil and aluminum chlorid, conducting away from such substantially in liquid form liquid form at a temperature above 600 body. vapors of lower boiling oils formed,

and supplying additional highboiling oil to said body at a temperature above 600 Fahrenheit.

5. The process of converting higher boiling oils into lower boiling oils which comprises establishing and maintaining a boil- 111 body of higher boiling oil and aluminum chlorid, conducting vapors of lower boiling oils formed away from such'body, supplying additional higher boiling oil substantially in liquid form at a temperature above 600 1*. and supplying heat directly to said body of higher boiling oiland aluminum chlorid.

6. The process of converting higher boiling oils into lower boiling'oils which comprises establishing and maintaining a boiling body of higher boiling oil and aluminum chlorid, conducting vaporsv of lower boiling oils away from such body, supplying addi-. tional higher boiling oil substantially and supplying heat directly'to said body of higher boiling oil and aluminum chlorid, said heat being supplied at a temperature not much above that of said body.

7. The process of converting higher boiling oils into lower boiling oils which comprises'heating a mixture of higher boiling oil and aluminum chlorid to from 500 to 600 F., conducting aw'a vapors of lower boiling oils formed, an

oils formed, supp ymg higher boiling oil 7 substantially in liquid form at a temperature above 600 F., and supplying additional heat directly to the body of higher boiling oil and aluminum chlorid.

. 9. T he process of converting higher boiling oils into lower boilin oils which ,com prises heating a mixture 0 higher boiling oil and aluminum chlorid to from 500 to 600 F., conducting awa vapors of lower boiling oils formed, supp yin higher boiling oil substantially in liquid orm at atemperature above 600 F., and supplying additional heat directly to the body of hi her boiling oil and aluminum chlorid, sai heat being supplied at a temperature not much above that of said body.

10. In the conversion of higher boiling oils into lower boiling oils with the aid of aluminum chlorid, the process which comrises establishing and maintaining abo iling body of higher boiling oil and 81111111111111! chlorid, conducting awa vapors of lower boiling oil formed, heatmg higher boiling supplying additional higher boiling oils substantially ur liquid form at a temperature above 600 F. 35

oil to a temperature higher than the temperature of said body, and adding the so heated oil substantially in liquid form" to said body of oil and aluminum chlorid.

11.- Inthe conversion of higher boiling oils into lower boiling oils with the aid of aluminum chlorid, the process which comprises establishing and maintaining a boiling bath of-oil and aluminum chlorid and supplying superheated oil thereto substantially in liquid form.

12. In the conversion of high boiling oil into low boiling oils with the aid of aluminum chlorid, the process which comprises establishing a boiling bath of higher boiling oil and aluminum chlorid and supplying superheated higher boiling oil of the same .character thereto substantially in liquid form. t

13. In .theconversion of higher boiling oils into lower boiling oils with the aid of aluminum chlorid, the process which comprises establishing a boiling bath of oil and aluminum chlorid, removing vapors of lower boiling oil produced and supplying superheated oil thereto substantially in liquid form in proportion to removal of vapors.

14, The process of producing lower 'boilin oils from higher boiling oils which comprises establishing and maintaining a boiling body of higher boiling oil and aluminum chlorid, heating higher boiling oil to a temperature higher than the temperature of the boiling body, conducting away from said boiling body vapors of lower boiling oil formed, adding to said-boiling body the so heated higher boiling oils substantially in liquid form at a temperature higher than the temperature of said boiling body, removing contaminated and used aluminum chlorid residue from the body of higher boiling oil and supplying fresh aluminum chlorid to said body of higher boiling oil.

15. The process of converting higher boiling oils into lower boiling oils which comprises heating a mixture of aluminum chlorid and higher boiling oil to a temperature sufiicient to cause ebullition, agitating the mixture, allowing sludge of aluminum chlorid formed to settle underthe body of higher boiling oil and aluminum chlorid, removing such sludge, adding additional aluminum chlorid to said mixture of aluminum chlorid and the higher boiling oil, conducting away vapors of'lower boiling oil formed, and adding to the said mixture higher boiling oil heated to a temperatureabove that. o the lit

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