US1476219A - Process of distilling with catalytic chemicals - Google Patents

Description

Dec. 4 1923.

G. L. PRlCHARD ET AL I PROCESS OF DISTILLING WITH CATALYTIC CHEMICALS Filed Nov. 21, 1921 2 Sheets-Sheet 1 Dec. 4 1923. 1,476,219

G. L. PRICHARD ET AL PROCESS OF DISTILLING WITH CATALYTIC CHEMICALS Filed Nov. 21, 1921 2 Sheets-Sheet 2 Patented Dec. 4, 1923.

enonen L. raron'aan AND HERBERT HENDERSON. or roar ARTHUR, Texas, AS- SIGNORS T0 GULF REFINING COMPANY, or PITTSBURGH, PENNSYLVANIA, A coa- ]PORATION OF TEXAS.

Application filed November 21, 1921. Serial No. 516.5%.

Catalytic Chemicals, of which the following is a specification.

This invention relates to processes of dis tilling with catalytic chemicals; and it comprises a method of distilling oils with a catalyst such as aluminum chlorid for the pro duction of oils of lowered boiling point, wherein a bath of oil and anhydrous aluminum' chlorid is established and maintained at a temperature sufficient to permit free ebullition and production of large volumes of vapor, the heat necessary in the main tenance of temperature and for the production of vapor being afforded by continuously removing material from said bath, passing it through heating means and re turning to said bath; all as more fully hereinafter set forth and as claimed.

As is now known, oils on distillation with anhydrous aluminum chlorid under carefully regulated conditions, can be made to give large yields of products of a boiling point lower than that of the oil distilled. This is 'now commercially used on a large scale in the production of gasoline, etc., from oils of higher boiling points. The conditions necessary for successful operation are many.

and in practice much attention must be paid to details. J

Aluminum chlorid is a hard, more or less crystalline, rather volatile material, reacting violently with water, and having an energetic action upon hot oils; the action which is utilized in the stated process. It is not particularly soluble in petroleum oils and when it is added to a body of such an oil,'it melts down to a heavy, oily liquid with a portion of the oil; this heavy liquid under lying the rest of'the oil. In distilling oils with anhydrous aluminum chlorid, it is necessary to use energetic agitation to keep this heavy liquid stirred up through the rest of the oil and present an extensive area of contact between the two liquids. On heating ,above thatof the bath. is precluded.

such an agitated mixture, it enters into free ebullition, with the production of vapors of lower boiling oils, at a temperature which is often somewhat below the natural boiling point of the oil under treatment. In the case of gas oil and the like, the temperature is usually somewhere between 500 and 600 F. The aluminum chlorid does not retain its converting activity indefinitely, after a time becoming relatively inert. As the converting action goes on. the thickens progressively, becoming tarry or asphaltic, and it is finally discharged as what is known as chlorid residue or chlorid sludge; this material being then treated in various ways, not relevant here, for the recovery of aluminum chlorid. With this change in consistency goes a progressive lessening of activity. The length of time during which a given charge of aluminum chloridretains its activity to a substantial degree varies very much with the conditions of operation and it has been found by experience that slight changes in such conditions often give a materially lengthened period of activity; materially increasing the number of gallons of oil which can be converted by a given amount of aluminum chlorid. 1

Oneof the most important of these conditions is agitation. not only is the effective contact area between chlorid and oil body increased but the chlorid is kept subdivided and, to the extent that it is subdivided and suspended in the agitated body of oil, the danger of overheating it, of heating it to temperatures As stated, the composition of aluminum chlorid and oil forms a heavy liquid, underlying the rest of the oil and tending to settle to and bake on the heating surface with the usual types of bottom heated stills used in this art. \Vhile at first the heavy liquid is easily stirred up into and through the body of oil, as its consistency thickens stirring up becomes progressively more difficult it becomes difficult and finally impossible to keep it off the bottom of the still, where it clings and bakes. The formation of a baked-on layer not only materially impedes the transmission heavy liquid.

By vigorous agitation of heat but in becoming overheated causes a rapid diminution in the activity of the charge in the still.

In this type of operation while the sheer temperature required for distillation is not particularly high comparatively large amounts of heat are necessary. In one way of looking at it, the process is one of converting liquid oils into vapors and, as in all distillations, the number of thermal units required is comparatively large. Much heat must be transmitted through the still walls; and the formation of the baked-on coatings referred to materially impedes this transmission with the result of requiring higher still Wall temperatures and greater superheat of the localized aluminum chlorid.

In another application, Serial no. 5165M; filed Nov. 19, 1921, we have described and claimed various ways of operating taking into consideration the noted facts. in the present invention we arrange for a forced rapid circulation of the bath material to and through a tubular heater and back to the reaction chamber.' in so doing, no op portunity is afforded for the chlorid to deposit on heating surfaces or collect in pockets of any kind. ,The reaction vessel itself may be wholly unheated or merely heated enough to compensate for radiation and the heat units necessary for maintaining temperatures and furnishing vapor sup- -pli'ed in the heater. By this rapid circulation, the heavy liquid is kept disseminated through the oil body in finely divided form, giving a large effective contact area for reaction and preventing its acquiring any temperature above that of the circulating oil body. As a result, the longevity of the aluminum chlorid is much promoted.

To accomplish these ends, we establish and maintain a suitable bath of oil and aluminum chlorid at reacting temperature in a vessel provided with a. good heat insulation. This vesselis connected with an outside heating device having relatively narrow heating tubes mounted in a suitable furnace or the like. The connections are such as to enable a continuous circulation of material from the bath to and through the heating device and thence back to the bath; and means are employed to cause a forced circulation. Sometimes we employ a pump for producing this forced circulation, but it is sometimes convenient to produce it by a sort of injector action; supplying the oil intended for the bath under heavy pressure in such a way as to produce this circulation. \Vhere the oil is, admitted to the system in a preheated condition, as it sometimes is, the necessary pressure of the oil may be p oduced in the preheating operation. In this event. the. forced circulation is produced by a jet of mingled vapors and oil.

By using comparatively narrow tubular Figure 2 is a top plan view of Figure 1,

and

Figure 3 is a segmental detail section showing heating coils in the converter or expansion chamber.

The heater is mounted in the furnace 1 having fire box 2, steam and oil or other burner 3, archd and bridge wall 5. For

T avertically arranged heater there is provided shaft 6 having" baffles 7 and fiue 8 leading to the stack 9. The interior of the furnace. may be lined with fire-brick 10 and be covered with heat insulating material 11 (such as kieselguhr or sil-o-cel or the like) which in turn may be covered with fire clay or bauxite or the like 12. Mounted in the shaft of the furnace and suspended therein is the heater designated as a whole by 18. This heater comprises the upper drum 14 and the lower drum 15, and may lie-suspended in place by means of the ears '16 attached to suspension rods 17, secured to the cross bars 18, supported by the standards 19. The heater may also be supported by means of the angle irons 20, riveted or secured to the drum 1e, resting upon the angle irons or plates 21, in turn riveted to the standards 19 and resting upon the top of the fire bricks and insulation. For the purpose of the present invention, it is advantageous to use a tubular heater. The drums 14: and 15 are in communication through a plurality of tubes 22. Leading from the topof the drum 145 is the heat insulated pipe 23, provided with the thermostatic control 2 L in operative connection with the burner 3, so that the feed of fuel to the burner may be regulated in accordance with the temperature of the oil or oil and vapors leaving the drum 11. This thermostatie control feature is no part of this invention, it being a standard equipment for usein heating apparatus: and the details are therefore not shown. The pipe 23 is provided with three valved inlets 25. 26 and 27, leading to the converter 28 at different points along its height. The inlet at 27 may extend in the converter and. may be provided'with perforated cross pipes 27.

Original oil to be heated is admitted through pipe 29 leading to the pump 30, which in turn leads tot-he lower drum 15 (MID through valved line 31. The converter 28 is provided with a pluralityof valved ofitakes 32, 33 and 34, leading from diiterent points along the height of the converter and with the valved otttake 35 leading from the bottom. The pipe olftakes 32, 33 and 34 are in communication with the pipe 36 leading to the line 29 through which material from the converter may be sent to the pump and directly to the drum through line 31. If desired, this material may be shunted around the pump by means of the valved bypass line 37 (see Fig. 2). The line leading from the bottom of the converter is provided with the valved branch 38 for conveying away coky residue or for removing the contents of the converter as hereinafter described.

Referring to the converter or expansion chamber 28, it comprises a steel or other suitable vessel 39, provided with the settling basin or cone-shaped bottom 40. This con verter may be lined with heat insulation material, such as kieselguhr or sil-o-cel, asbestos, or the like, 41.

Although it is not necessary for the operation to be hereinafter.described, the still and converter 28 is shown as provided with stirring mechanism which is advantageous in some uses. The shaft 42 carries a plurality of, preferably, staggered paddle arms 43, suit-ably keyed to the shaft and provided with sets of chains 4st adapted to assist in the stirringand adapted to scour the sides of the converter. The shaft is journaled in the trunnion 45 mounted in the bottom of the converter by means of the brackets 46, and is also journaled through a stutling box 47 at the top of the still. The shaft carries beveled gear 48 meshing with beveled pinion 49 carried by shaft 50 which also carries the pulley 51 driven by the belt or chain 52 leading to reduction gearing 53 driven by motor 54.

' The still is provided with an inlet 55 for introduction of oil or ofaluminum chlorid or of a magma of oil and aluminum chlorid. Leading from the still is the vapor line 56 leading to air cooled condenser 57 provided with vapor line 58 leading to a second air cooled condenser 59. Each of these air cooled. condensers is provided with the thermometer 60 for a purpose hereinafter described. Each air cooled condenser is further provided with backtrap line 61 for returning condensates to the still, preferably below the level of the contents thereof, by means of line 62. Vapors leaving the air cooled condenser go by line 63 to the coils (not shown) in the water cooled condenser 64:. This is mounted by means of suitable supports 65 upon any desired foundation arrangement 66.

or reasons to be hereinafter explained, it is sometimes advantageous to heat the contents of the drum and still and for this purpose we provide interior heating means,

such as the steam coil 67 having inlet 68 and outlet 69. This coil may be located in the basin or cone-shaped bottom of the converter. Steam is supplied to the line 68 by means of the superheater 70.

Our process is performed as follows:

Assuming anhydrous aluminum chloridto I be the catalyst used with a high boiling oil and that gas oil or kerosene oran oil intermediate the two is used as the high boiling oil which is to beconverted into the lower boiling oil, the still or converter 28 is sup plied with a magma of anhydrous aluminum chlorid and high boiling oil, advantageously of the same composition as that to 'be converted. This magma may be admitted through line 55 which extends normally below the level of the oil in the converter when in operation. High boiling oil is then admitted either through line 55 or from the preheater. High boiling oil is sent to the preheater from line 29 to pump 30, thence be admitted at any one of a plurality of points. The stirrer is started and one or more of the valves on lines 32, 33, 34-and 35 opened. These lines lead to the pump, with the result that the contents of the still or converter may be sent back to the heater. If desired, the contents may be shunted around the pump by means of the line 37 and thermal circulation relied on, thus keep-ing aluminum chlorid out of contact withthe pump. Also, ifdesired and when necessary, heat additional to that supplied by the heater may be furnished by the interior heating means shown in Figure 3. It isadvantageous to operate the pump so that there is a rapid and continuous circulation of the material from the still to the heater and back again to the still; a circulation which will be rapid enough to prevent deposit of aluminum chlorid or aluminum. chlorid residue in the tubes. According to the arrangement shown, we may deliver the high boiling oil in admixture with aluminum chlorid to the heater at several different points, either in the vapor space as shown by line or beneath the normal level of the contents as shown by lines 26 and 27. Or we may open valves on these lines slightly and deliver the preheated mixture at all these points or any of them. Similarly, we may send the mixture back to the heater on either the pressure or the suction side of the pump and we may tap it from the converter or still at any one of a plurality of points.

As stated, after a time, the aluminum chlorid tends to settle as a rather heavy vis- (rid material, usually termed coky sludge or aluminum chlorid sludge. This settling will take place in the basin at) of the converter and the aluminum chlorid sludge thus settled may be withdrawn from time to time or continuously by means of lines 35 and 38,

' and sent to aluminum chlorid recovery apnations with the oils from the vapors 01" low.

paratus.

Vapors of low boiling oils formed, vapors of some higher boiling oil and vapors of aluminum chlorid and its combinations with the oils, pass from the converter by line 56 to the preliminary air cooled condenser 57 from which the condensate flow back by means of lines 61 and 62 to the still or converter, best below the level of the contents. Any vapors not condensed in preliminary air cooled condenser 57 pass by line 58 to the second air cooled condenser 59, condensates from which flow back to the still through lines 61 and 62. When properly controlled, the vapors from 59, which will be vapors of low boiling oils, will leave the condenser 59 through line 63 and go tothe final or water cooled condenser 6 1.

,In operation, in order to make a separation of aluminum chlorid and its comb i boiling oils, the rate of speed of running and the heat conditions are so controlled that the volume of vapors in the second air cooled condenser should not register a temperature substantially above 350 F. on the thermometer. Since aluminum chlorid and its combinations with oils will condense at about that temperature and below, they are condensed, together with the higher boiling oils, and return to the still through the backtrap lines described.

As has been stated, it is necessary to provide means for thoroughly agitating and stirring the contents of the still, not only to secure the best possible contact between the catalytic agent and high boiling oil, but also to prevent settling of the aluminum chlorid and its combinations with the oil, particularly after the operation has been in progress for a short time. And we may use the stirring mechanism described for that purpose in combination with the CTL culation means. However, we have found in actual operation that the stirring mechanism is not essential when the high boiling oil and the aluminum chlorid are stirred by circulating them rapidly through the tinuously removing possible under conditions may be supplied continuously to the heater by line 29. That is, it may be led in in (3 where solid materials settle and from which oil or the like may be removed by line 7 1. This arrangement is not claimed in this application.

During the distillation steam may be admitted to the coil 67. In the heater the oil may be heated to the reaction temperature, or above or below suchtemperature-in the latter event, supplemental heat from the steam coil being used.

\Vhat we claim is 1. The process of converting higher boiling oils into lower boiling oils which comprises establishing and maintaining a bath of a mixtureof a catalytic material of the aluminum chlorid type and of higher boiling oil, continuously removing a. portion of the said bath, heating it, continuously returning it to the bath and continuously removing i'rom the bath vapors of lower boiling oils formed.

2. The process of converting higher boiling oils into lower boiling oils which comprises establishing and maintaining a bath of a mixture of anhydrous aluminum chlorid which will also insure thorough mixing. High boiling oil and of higher boiling oil at a temperature giving free ebullition, continuously removing a portion of the said bath, heating it and continuously returning it to the bath and continuously removing from the bath vapors of lower boiling oils formed.

3. The process of converting higher boiling oils into lower boiling oils which comprises establishing and maintaining a bath of a mixture of anhydrous aluminum chlorid and of higher boiling oil, continuously removing a portion-of the said bath, heating it to a temperature above its boiling point and returning it to the bath, and confrom the bath vapors of lower boiling oils formed.

4. In the conversion of higher boiling oils into lower boiling oils with the aid of a catalyst of the aluminum chlorid type, the process which comprises establishing a body of higher boiling oil and of the catalyst, and circulating this body to outside heating means and back to the body, while removing from the body vapors of low boiling oil formed.

5. In the conversion of higher boiling oils into lower boiling oils with the aid of a catalyst of the aluminum chlorid type, the

process which comprises establishing a ody of a mixture of such higher boiling oil and of the catalyst, and circulating this body to outside heating means,-heati ng to ebullitionand returning it to thesaid body. 6. Process of converting higher boiling oils into lower boiling oils which comprises heating a mixture of higher boiling oil and 'of anhydrous aluminum chlorid, delivering sai mixture to a distillation apparatus, and during distillation in said apparatus withdrawing a portion of said mixture,

sending the said portion back to the heating means, whereby, a. portion of the mixture is kept in constant circulation through the heating means and back tothe still.

7. Process of converting higher boiling oils into lower boiling oils which comprises heating a mixture of highervboilingoil and of anhydrous aluminum 'chlorid, delivering said'mlxture to a distillation apparatus, and

'during distillation in said apparatus, withdrawing a portion of said mixture, sending the said portion backto the heating means, whereby a portion ofthe mixture is kept in constant circulation through the heating means and back to the still, and constantly supplying fresh higher boiling oil.

8. 'rocess of converting higher boiling oils into lovrer boiling oils which comprises heating amixture ofhigher boiling oil and anhydrous aluminum chlorid, vdelivering said mixture to a distillation apparatus, and during distillation in said apparatus, withdrawin a portion -o f,said mixture, sending the sai portion back to the heating means, whereby a portion of the mixture is kept in constant circulation ,through the heating means and backto. thestill andconstantly k 10. The process of converting higher boil-- ing oils into lower boiling oils which comprises establishing a hot body of higher. boil-- removing vapors of low boiling oil;

that from oils in admixture with aluminum chloformed-and constantly tapping oil from a low point of-said body a portion of said mixture, sending it to heating means, and

. heating'it to a temperature'above the boiling point, returnin .it to the body at a higher point than t at from which it was.

tapped. v

11. The process of converting higher boilin oils into lower boiling oils WhlCh' OOIIb prises'establishinga hot body of higher boiling oils in admixture with aluminumchlorid, removing vapors of low boiling .oil formed and constantly'removing a portion of'said body, heating the said portion and said'body.

returning it to-the said body and heating ".In testimony whereof we have hereunto signed our names at Port Arthur, Texas, this 14th day of November, 1921. 1

, GEORGE L. 'PRIGHARD.

HEBBERT'HENDERSON'.

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