US2248118A - Process of cracking mineral oil - Google Patents

Description

July 8, 1941 A. E. PEW, .JR v 2,248,118

PROCESS 0F CRACKING MINERAL OIL Filed Oct. 8, 1957 4 Sheets-Sheet 1 6,45 0M an arms? (WARE/N6 5706A :m vf

l' #froh/@ya july 8, 1941- A. E. PEw, JR 2,248,1 18

PRocEss oF CRACKING'MINERAL on;v y

Fileqoct. e, 41.937 4 sheets-sheet 2 RM n C fr# F July s, 1941.

A. E. PEW, JR

PRocEssoF CRAGKING MINERAL OIL Filed oct. 8, 1937 4 sheets-sheet s O'oOOOOOooOooOooOooO o`o oooooooooooooo .'i'

Mer/ue //v @LM/2M .Ju1ys,1941. AEPEWJ'R 2,248,118

PROCESS OF GRAUKING MINERAL OIL Filed oct. ,8. 19:57 i 4'sheeis4sheez 4 EA y Patented July '8, 1941 PROCESS OF CRACKING lllINERAL OIL Arthur E. Pew, Jr., Bryn Mawr, Pa., assignor, hy

mesne assignments, to Houd'ry Process Corpora.- tion, Wilmington, Del., a corporation of Dela- Ware Application October 8, 1987, Serial No. 168,012

' 9 Claims. (Cl. 196-49) This application is a continuation in part of an application filed by me on the 6th day -of March, 1934, Serial No. 714,254.

The cracking of petroleum or of a selected fraction thereof, such as-gas oil, is usually effected solely by thermal conversion, although it is well known that cracking is effectively induced and/ or promoted by meansof many known catalyzers, which increase the yield of decomposition products such as gasoline, at a given temperature or give an equal yield of such products at a lower temperature, besides producing, where gasoline is the product, a much better anti-'knock gasoline. Usually the oil is heated to effenct'vaporization and the oil in vapor phase passed through the mass of catalyti'cmaterial. The temperature of vaporization may be -below an effective cracking temperature under purely thermal conditions, but may be well within an effective cracking temperaturerange in the presenceof a catalyst.

Or the tempera-ture of vaporization may be high enough and the time of heating long enough to effect some cracking of the vapors before their entry into the catalytic chamber. It is therefore desired cracking. It is also possible to supply heat to the cracking zone to maintain the vapors at or close to their entering temperature.

Notwithstanding the known advantages of cracking in the presence of a catalyst, they do not suffice to overcome the objections thereto, wherefore the commercial-practice of such processes is prevented or much restricted.

There are several serious objections to processes involving cracking inthe presence of a catalyst wherein reliance is had solely upon the heat of the entering vapors to secure an effective cracking temperature. A serious objection is that there is a continuing drop in the temperature of the oil vapors during their passage through the catalytic chamber. This condition is due to the fact that while the 'cracking reactionis partly exothermic and partly endothermic, the net reactionis endothermic. A fall in temperature during cracking is a condition precisely the opposite of that required to most efficiently crack. When oil, in either liquid or Vapor phase, is

raised to a given temperature, cracking proceeds 'I' the temperature gradually decreases the rate of 55 cracking decreases much more rapidly. It is, therefore, apparent that if there is a substantial drop in the temperature of the oil vapors during their passage through the catalytic mass, as therel will be if the heat of the entering vapors is solely relied upon to establish the desired temperature of cracking in the contact chamber, a condition precedent to the most effective cracking, namely, a continued maintenance of desired temperature or a progressive rise in temperature -during cracking, is not present. It is true that .by heating the vapors, before admission to the catalytic mass, to a high cracking temperature, there may be efficient 'cracking `during even 'a very short passage of the oil vapors through the mass, but this procedure involves substantial cracking of the vapo'rs before they enter the contact chamber. This is objectionable if it is desired to obtain the full advantage of cracking in the presence of a catalyst; and, further the higher the temperature, the more rapid the deterioration of the catalyst, due to carbon deposition on the surfaces of pieces or particles of catalytic material which requires frequent regeneration, usually in situ, by passing an oxygencontaining regenerating fluid therethrough. Indeed, deterioration of the catalyst is a-serious problem, since the yield of the lower boiling hydrocarbon mixture desired gradually diminishes,

" 'due to deteriorationoi the catalyst, under any temperature conditions and so rapidly diminishes under high temperature conditions as to make it advisable to carry on the cracking process at atemperature as low asis consistent with a satisterial so as to prevent a substantial drop of temperature while the oil is passing therethrough have not hithereto been successful, due tothe practical difliculty of transmitting enough heat and of imparting such heat uniformly to the entire mass of catalytic material. For example, jacketing the catalytic chamber and flowing superheated steam or hot gases through the jacket is effective only to maintain orraise the temperature of that outer Zone of .the mass adjacent the hot jacket and is not effective to raise the temperature of the entire mass or to establish substantially uniform temperature conditions throughout the mass.

The object of my invention is to so far eliminate or minimize the objections to the performance of the cracking operation in the presence of a catalyst as to make such mode of cracking commercially practicable. More specifically, the object of the invention is to so practice the process as to secure at least as good a yield of the low boiling hydrocarbon desired as withA the most efficient purely thermal process and to produce a product which is distinctly superior, in respect to anti-knock qualities, to lthat produced by any known purely thermal process.

One feature of the process comprises the vaporization of the oil or reactant fluid at a temperature below that which is effective to crack under purely thermal conditions, followed by the passage of the oil into and through a mass of catalytic material which is maintained at a higher I and passes it under pressure through line 9 to the heating coil 8 within the tube still 1.

From the heating coil 8 the stock is passed through line II to a vaporizer I2. Within the vaporizer I2 the heated stock expands into vapor and passes upwardly through the trays which are diagrammatically illustrated. A portion of the vapors is withdrawn from the top of the vaportemperature than that of the entering vapor;

the process also involving such transmission of heat to the mass as to maintain it throughout at about the same temperature so that the temperature of the outowing cracked gases is abovev I as baiiies, etc.

tained at progressively higher temperatures,

thereby establishing the temperature conditions required to effect maximum cracking. Another feature of the invention is the provision of an endless ring of cracking chambers, only one group of which'is being employed on stream or in the path of flow of the vapors at any given time, chambers on which contaminants or combustible deposits have accumulated being successively removed from said path and (other) chambers which have been restored to active condition, as by an exothermic regeneration carried out with an oxygen-containing regenerating medium, being successively inserted in said path.

'I'he catalytic material in each chamber is regenerated while such chamber or zone is bypassed, and this is done within a controlled temperature range since, as above pointed out, the higher the temperature to which the catalyst is subjected, the more rapidly it deteriorates. Ina preferred aspect or embodiment, each chamber, while active, becomes successively one of diierent groups of chambers and alters its series position in the several groups as the operation progresses, its temperature being accurately regulated in accordance with its series position. l

In order that the process may be more clearly understood, and in order, also, to enable the process to be practiced without the necessity of eX- perimentally developing an apparatus for practicing the process, I illustrate in lthe accompanying drawings a complete cracking plant or conversion and temperature control apparatus adapted to practice the process, as well as desirable structural details of the cracking elements per se.

Figures l and 2, taken together, constitute a flow sheet disclosing a complete conversion or cracking unit for practicing my improved process for producing, for example. a lower boiling product from a higher boiling charging stock. Figure 3 is a vertical sectional view of one of the catalytic chambers in which the oil is cracked. Figure 4 is a horizontal section through a part of vsaid chamber. Figure 5 is a diagram of one arrangement of catalytic chambers. Figure 6 is a diagram of another arrangement of catalytic chambers.

I indicates a line through which charging stock, fed to 'the apparatus. flows through heat exchangers 2 and 3, wherein it is partially heated by stock flowing from a later stage in the process. as will hereinafter be described. 'Ihe pump 6 picks up the preheated stock flowing through line exchangers to izer through line I4 and passes through condenser I5. The condensed liquid is then pumped back to the vaporizerhroughv line I1 by means of pump I6 to .serve as` reflux liquid within the vaporizer. A stock which is not vaporized on entering the vaporizer, or which is condensed on the trays, is drawn off through line I3 from the bottom of the vaporizer.

The vapors to bev further treated pass oi through line I8 at the top of vaporizer I2, and pass through separator I9 in""which entrained droplets are removed by mechanical `means such These entrainedV droplets fall to the bottom of the separator and pass by gravity through line 20 to the bottom portion ofthe vaporizer I2 and thence through line I3.

The vapors which, as far as possible, have now been freed of entrainment, leave the separator through line 2| and pass through expansion valve 22 and thence through a Venturi tube 23 or any other appropriate mixing device. A line 24 is also connected to mixing device 23 for the admission of superheated steam or heated dry hydrocarbon or other inert gas such as carbon dioxide or ue gas.

From the mixer 23 a line 26 leads to a coil 29 within a furnace-28. From the coil 29 a line 30 leads to a cracking apparatus, which may be a single chamber or, very much preferably, comprise a series of chambers 3|, 32 and 33, arranged or joined' as shown or in other desired manner, or a ring of chambers 9| to |02 as shown in Fig. 6.l These chambers, which include the most important elements required for the practice of the process, are hereinafter described in detail. A by-pass line 21 connects lines 26 and 30. Lines 26, 21 and 30 are provided with suitable valves so that all vapors owing from mixing device' 23 may completely or partially by-pass the heating coil 29. l

The cracked vapors .leaving the cracking chamber, or any one or more of the chambers of the series, pass through line 31 to a distillation tower 38, wherein they may be fractioned to produce, for example, an overhead'gasoline vapor cut, a side stream which may be heavy naphtha or light gas oil, and a. bottoms.

The side stream is withdrawn through line 5 and is passed through heat exchanger 2, while the bottoms are withdrawn through line 4 and passed through heat exchanger 3, both the side stream and bottoms giving up their heat in these preheat 4the stock flowing to this system.

' The overhead vapor cut is removed from the tower through line 39 and passes to a clay tower 41. wherein the vapors are purified by contact with fullers earth, bentonite, or like treating or chemical stabilizing medium. The purified vapors pass from the clay tower 41 through line 49 to a condenser 50 and the condensed liquid is then passed tothe product accumulator 5I. The nolymer fraction which is formed in clay tower 41 is withdrawn through line 48.

In order to provide for reflux within the distillation tower 38, a portion of the overhead v a'- through line 40 and passed through condenser 4| to reiiux accumulator 42. From the reux accumulator 42 the condensed and cooledl reflux stock is withdrawn through line 43 by means of pump 44 and is forced to the top of the tower 38.

The permanent gases which are not condensed in the condenser 4| are Withdrawn from the reflux accumulator 42 by means of line 46 and any surplus reflux liquid may be withdrawn through line 45.

The final product is withdrawn from theaccumulator through line 53. The fixed gases not condensed within condenser 50 are withdrawn from the product accumulator 5| through y line 52.

Each of the cracking chambers 3|, 32 and 33 (see Figs. 3 and 4) may take the form of a cylintion, it can, when introduced to the tubes in when introduced to the tubes 1U, is so close to its temperature of condensation that, in the endothermic reaction, it can, when introduced to the tubes 10 in vapor phase, impart heat to the mass by condensation, while, in the exothermic reacliquid phase, extract heat from the mass by vaporization.

Apparatus applicable to the present case isdisclosed in various patents heretofore issued to me,v for example, in Nos. 1,714,811 and 1,714,812, issued May 28, 1929. The main features of such apparatusare shown in Fig. 3, Mercury from a reservoir or boiler 1| flows through a pipe 12,

drical casing 60 provided Awith tube sheets prov- 'y viding top and bottom headers or manifolding chambers 6| and 62 and between them the reac- 'tion zone or catalytic cracking chamber, which is substantially filled (except for the space occupiedv by'the tubes hereinafter described) with bentonite, bauxite, fullers earth, or any other siliceous or adsorptive catalyst (e. g. in theform of pieces or particles) which has been or may be found effective for thel reaction desired, these `catalysts `being preferably in activated form rather than in their natural condition. A multiplicity' of tubes 64 extends between the tube sheets and are closed at the bottom and are open at the top to allow the extension therewithin'of vapor inlet tubes 83, whose upper ends extend through the upper tube sheet and communicate with upper header 6|. Each tube 63 is in concentric ory telescoping relation with a corresponding tube 64 and extends down to vnearly the lower end of tube 64 and there opensV into tube |54. A multitude of vapor outlet tubes 65 are carried by and extend through the lower tube sheet and there communicate with lower header 62. These tubes extend upward throughout nearly the entire height of the chamber andare closed at the tances and in symmetricalrelation, a number of tubes 65 so that oil vapors passing from tube 30 through header 6| and tubes 63 into tubes G4, pass laterally through the perforations in' tubes 64, thence through the catalytic material with which the chamber is packed, thence through the perforations in tubes 65 into such tubes, thence through such tubes into header 62 and thence through pipe 81 away from the reaction zone, and may pass to the next catalytic cham` ber of the series, 'as desired. IAfter passing through any additional treating or reaction zone, ory not, as the particular circumstance dictates, e. g. through chamber 32, pipe 38 and chamber 33, the finally cracked vapors 4pass through pipe 31 to the fractionating tower 33.*

The casing 60 of each cracking chamber should be insulated from thesurrounding atmosphere by any suitable means such as a jacket 69 for hot gases or by insulating material. In case the insulating function is effected by hot gases, these need not impart any heat to the chamber, since heat so applied does not penetrate the mass of catalytic material or does not penetrate it to the extent required t establish and maintain uniform heat conditions throughout the mass. Such uniform heat conditions are effected, preferably, by means of a heat exchange fluid, such as mercury, or vany other equivalent substance, flowing through a multitude ,of tubes 10, which,

controlled vby a valve 13, into a header 14 and thence into and through tubes 1U, thereby to effect heat exchange with and control the temperature of the vcontact material or catalyst in the chamber 3|, 32 or 33. Where the mercury or other heat exchange fluid is giving up heat to the contact material, as iny the aforementioned illustrative on-stream or `endothermic, reaction, rather than absorbing or withdrawing heat therefrom as would be the casein controlling an exothermic reaction such as the vabove indicated step of regeneration ,within arestricted temperature range, the heat exchange uid may be` supplied partly or entirely in vapor" phase, condensate forming and yielding up heat tothe contact material. Condensed or liquid mercury or like fluid, often accompanied .by some vapors, ows from heat exchange tubes 10 into header 15 and thence through a pipe 16 into a gas trap 11,` provided with a relief valve 18, and thence through pipe19 back to the reservoir or boiler 1|. 1 Valve 13 may be operated to control the rate of ilow of mercury, thereby regulating the pressure 4 within tubes 'I0 and thus regulating the temperature at which a heat exchange' fluid such as mercury will change state, i. e. will change from vapor to `liquid or from liquid to vapor. thereby' possible, a's illustratedNmore fully in said patents, to progressively increase the temperatures in the pipes 'I0 of successive catalyticchambers while maintaining the mercury, or like heat exchange medium, under conditions so that the same is at least to substantial extent in a liquid or condensed state, thereby maintaining such chambers at progressively higher temperatures. The pressure in the reservoir or boiler 1| may,

for convenience, be maintained at least as highI as the desired pressure in the pipes 'I0 of 4any of the catalytic chambers which it may be desired to heat to a higher temperature than the others, e. g., the last chamber 33 of the series, and may,

be higher than the desired pressure in the pipes umns balancesthe said difference in vapor pressure. l

The heating system described' is admirably adapted to provide a substantially precise control of the temperature or temperature range of` any of the catalytic chambers, so as, for example,

to maintain the same substantially at desired temperature and tov provide for, continuously maintaining substantially Vuniform or desired temperatures throughout all portions of the mass or bed of contact material. In general, the temperature of heat exchange liquid or medium which is flowed in direct heat conducting rela-- tion with the body of contact material, as through pipes 10, will be introduced linto the latter at a temperature 'approaching that desired in the contact material and departing from thelatter temperature suiciently only to eil'ect the desired amount of heat 'exchange with the contact material while avoiding, when desired, any sub-- stantial difference in the temperature of contact material adjacent' opposite ends of pipes 10. Pipes 10, or. tubesl 64 and 65 taken in connection with pipes 10, when such tubes are employed, divide the of contact material into a plurality of elongate intercommunicating reaction zones, which facilitates desired temperature control of all portions of the contact or catalytic material, regardless of the particular manner in which fluid reactants are passed through and in contact with such material. This permits reactant fluids orproducts and/or regenerating.

medium to pass from one elongate reaction zone the same temperature as the oil vapors, is mixed with the oil vapors inthemixer 23, and, by the partial pressure effect, insures the thorough drying of the oil vapors. "Usually, either the described sudden expansion of the oil vapors or the described addition ofa. dry gas will insure the thorough drying of the vapors.

The dried vapors are then quickly superheated stock. It is desirable, however, 4to heat the lvapor to another, where desired, in their passage through the contact material.

A valve-controlled pipe 34 connects with vapor lytic material of any chamber becomes impaired,

the valves controlling pipes and 31 may be closed and the valves controlling pipes 3l and 35 opened, 'and suitablegas blown through pipe 3l,v header 6|, tubes 63, 64 and 65, header 62 and pipe 35, in order to-regenerate the contact material. Such regeneration comprises, mainly, the removal, usually in situ, of supercially deposited carbon from the contact materialor catalyst and need not be particularly described, other than to say that it is intended to maintain the catalytic material Within a suitable temperature range so as to avoid deterioration due to high temperatures as by heat exchange with a suitable medium as above described and illustrated.

to so low a temperature anda/pr for so short a time as to prevent a material amount-of cracking, ialthough, less desirably, a limited amount of cracking may occur in the heater 28. Preferably, the temperature should closely approximate that in the rst crackingchamber, since the capacity of the catalyst to induce cracking is so great'that it is possible to effect, in the catalytic chamber, what would ordinarily .be considered complete cracking, at a temperature at-which substantially no' cracking is effected in heater 28. Thus-very effective cracking ofi the vapors may be eiected in a single catalytic chamber 3| at a temperature of between 820 and 850 F., and such low temperatures therein are often desirable, since the Y lower the temperature therein, the longer .the

I shall briefly illustrate the operation of the apparatus above described and shall, as a matter of illustration and not of limitation, specify certain pressures, temperatures and modes of op,-

eration. It must be understood that such specific conditions need not be adhered to inl actual practice, as the most desirable temperatures and vaporizer I2, Within which it is partly freed from entrainment by passing' counter-current Ito the reflux liquid owing down 'over trays therein. The vapors then ilow into separator I9, wherein they are further dried by mechanical means. The vapors then pass through line 2| to the expansion valve 22, where they are expanded to a pressure approximating 15 pounds gauge. At this time their temperature will have dropped due to their expansion to about 775 F. This sudden expansion vof heated vapors serves to thoroughly dry them. To make sure that no mist or small droplets remain in the vapors, superheated steam or other dry gas, such as dry hydrocarbon vapors or carbon dioxide,heated to about time during which it is economically practicable to operate without regeneration of the catalyst.

Thus, if the cracking temperature in chamber 3|` considerably higher than 4that of the entering vapors and considerably higher than a temperature of 850 F., although in such case the catalyst will deteriorate more rapidly.' It may be assumed, therefore, that the oil vapors enter chamber 3| at a temperature of 850 F. and are therein subjectedto a temperature of. 860 F., at which temperature, with a fresh catalyst, the yield of gasoline. will be about 40 per cent. more or less, depending on the particular charging stock and all conditions of operation.

It is clear, from the foregoing description, that vthe process is of great advantage if lbut o ne catalytic chamber is employed; and a process involving the use and temperature control of one such chamber, as herein illustrated and described,

is within the broader eld of my. invention. However, as hereinbefore explained, a maximum cracking effect'cannot be achieved by subjecting oil to a constant, however,v high, cracking temperature, but can only be achievedby raising the temperature, throughout a .temperature cracking zone, gradually or by increments. By providing `a series of s'uch cracking chambers, and passing the oil vapors therethrough successively, at temperatures (say) of 860 F., 880 F. and 900 F. successively, a very thorough cracking is eiected,

' giving not only a very high yield of gasoline, but

producing a gasoline having high anti-knock quality.

' three or more chambers.

It will be understood'that the series of three catalytic cracking chambers is merely illustrative Iyield. The number is limited, however, by considerations such as cost of installation and maintenance.

It should be stated that the use of a special vapor vheater 28 is not imperative, since it is possible to heat thev oil to the required temperature in coil 8; orwhat is more practicable, to so superheat the dry gas admitted at the mixer 23 that it will supplyy the heat that would otherwise be supplied in the special heater' 2'8. If heat is so added, the oil vapors will be by-passed, through pipe 21, to pipe 30 and the catalytic chamber 3|.

In any process involving cracking in the presence of a really effective catalyst, the efciency of the catalyst becomes impaired as the process proceeds, with a resultant gradual reduction in yield of the desired product. It is, therefore, desirable to maintain the catalyst in continuous use for a relatively short time and to then cut it out of operation and regenerate it. I diagrammatically show, in Fig. 5, three series of catalytic chambers, namely 80, 8|, and 82, each series comprising One series only is in operation during .anyvgiven time. While one series is in operation, the other two series are undergoing regeneration. The time required for regeneration is usually approximately equal to the time during which the catalyst is in the oil circuit, so that the provision of three (or more) series of catalytic chambers not only gives ample time for regeneration, but provides for maintaining any series in circuit for so comparatively short a time that it may be cut out of the oil circuit before its eiiiciency becomes seriously reduced. 'Ihe heated oil vapors flow from pipe 30 into a header 83 (Fig. 5) and thence successively through the catalytic chambers of one of the series 80, 8|, and 82 and thence into header 84 and into pipe 31. After the lapse of a given time (say two hours), the active series is cut out of the oil circuit and one of the other series is 'brought into the oil circuit, by obvious manipulation of valves which need not be described. Then the second series is cut out of the oil circuit and the third series brought into the oil circuit. Then the rst arrangement is re-established.

While such arrangement and operation are entirely practicable, it is obvious that to the extent that the yield drops during the continuation of the operation of any given catalytic chamber or series of chambers, to that extent the yield will vary during the operation ofthe plant. To secure an approximately constant yield I carry out the process in the following manner. An endless ring of catalytic cracking chambers is provided. 'I'he hot vapors from heater 28 pass successively through a group of (say) three chambers and bypass the remaining chambers. After the lapse of a given time, one of the active chambers is removed from the oil circuit and one of the previously inactive chambers substituted, forming a new active group. This method of cutting out one chamber of the temporarily Vactive group'and simultaneously substituting one of the previously i inactive chambers, which has been restored to active condition by regeneration, after the'lapse of a given time interval, is carried on indefinitely. There is thus incircuit, just after each change, three chambers, one chamber containing fresh f pipe 31.

catalyst, another that has been in operation during one time unit and another that has been in operation during two time units. The greater the number of chambers in operation during each time unit, the more nearly constant will bey the yield and character of products from the apparatus.

In Fig. 6 is shown in diagram an apparatusadapted to carry out the process Ain accordance with the immediately,V precedingdescription. Twelve catalyticchambers, 9| to |02 inclusive, are shown. The hot oil vapors flow from pipe 30 into a header |03'. Each catalytic chamber is connected withy the header |03 yby a, valve-controlled vapor. inflow pipe |04. Each :hamber is provided with an outlet pipe v|05 hating valvecontrolled branches |06 and `|01 lcommunicating respectively with the vapor inflow pipe |04 of the next chamber of the series and with a header |08 for outflowing cracked'va'por.

Let it be assumed that the valves are so operated as to cause the hot oil vapors to flow from pipe 30 and header |03 through chambers 9|, 92

and 93 successively and thence to header |08 and After a given time interval thevnecessary valves are manipulated to cut out chamber 9| and shift the flow through chambers 92, 93 and 94. After another equal time interval the necessary valves are operated to cut out chamber 92 and shift the flow through chambers .93, 94 and 95; and so on throughout the ring.

If it be assumed, but only for convenience of illustration, that it is desired to maintain each chamber in operation for three consecutive hours and to maintain three chambers always in operation, it will be understood that the several chambers may be in operation during the following periods. ber 92 from 1 to 4, chamber 93 from 2 to 5, chamber 94 from 3 to 6, chamber 95 from 4 to '1, chamber 96 from 5 to 8, chamber 91 from 6 to 9,

chamber 98 from 7 to 10, chamber 99 from 8 to 11, chamber |00 from 9 to 12, chamber |0| from 10 to 1 and chamber |02 from 11 to v2. Chambers 9|, 92, and 93 will be simultaneously in operation from 2 to 3 oclock, chambers 92, 93, and 94 from 3 to 4, chambers 93, 94, and 95 from 4 to 5, chambers 94, and 96 from 5 to 6, chambers 95, 96, and 91 from 6 to '1, chambers 96, 91 and 98 from '1 to 8, chambers 91, 98, and 99 from 8 to 9, chambersl 98, 99 and |00 from 9 to 10, chambers 99, |00 and |0| from 10to`11,chambers |00, |0| and |02 from 11 to 12, chambers |0|, |02 and 90 from 12 to 1 and chambers |02, 9| and 92 from 1 to 2.

It is obvious that a greater number of chambers may be included in the active series during any given hourly (or other) period, and that the total number of chambers may be increased lor diminished. `'I'he specc illustration given provides more than ample time for effecting regeneration of the catalytic material contained in any chamber during its period of inactivity. By so carrying on vthe process, a nearly constant efficiency of the processjmay be maintained, with a nearly constant yield of the desired low boiling product.

It is obvious that the pipe connections' to the ring of catalytic chambers may be so arranged that the chamber which,` at the expiration of each hourly (or other period) is brought into the oil vapor circuit may operate as the first, instead of the last, consecutive chamber of the newly established circuit; and that the chamber which, at the expiration of each hourly (or other) period, is

Chamber 9| from 12 to 3 oclock, cham-l cut out of the oil vapor circuit, will be the chamber that is functioning as the last, instead of the iirst, consecutive chamber of the series.

While I have applied the term ring to the arrangement of contact chambers shown in Fig. 6 andihave thereinillustrated a'ring-like arrangement,` it vwill be understood that the actual structural arrangement may have no resemblance to a iringff although the word may be even then apt tofmkapply to the process actually carried out vin any structural arrangement. y

While the hereinbefore described specic example of the process is ofthe cracking of gas oil to gasoline, the process ,is also applicable to the cracking or transformation of heavy naphtha, kerosene, fuel oil and (exceptionally) gasoline or a gasoline fraction, and the desirable reaction temperature will vary with the charging stock, being, for example, usually progressively higher in the case of cracking of progressively lighter fractions. v

What I claim and desire to protect by Letters Patent is:

1. The process of cracking the vapors of a mineral oil charging stock which comprises heating the vapors to within a temperature range Within which no eflicient cracking occurs during said heating period but within which range rapid and efficient cracking would occur during such period in the presence of the catalyst hereinafter specified, and then flowing said heated 'vapors through a mass of adsorptive catalytic materialadapted to induce such rapid and efficient cracking within said temperature range, and while the oil vapors are so flowing within said mass supplying heat thereto to compensate for that absorbed by the net endothermic cracking reaction and thereby maintain the oil vapors throughout their entire flow through said mass at a temperature within said range bytransfer of heat from a multiplicity of symmetricallyv disposed streams 'of heating medium flowing through but out of contact with the catalytic material so that the cracked vapors leave the mass at a temperature withinsaid range and not below that of their entry thereinto.

2. The process of cracking the vapors of a mineral oil charging stock which comprises heating the vapors to within a temperature range within which no efficient cracking occurs during said heating period but within which range rapid and efficient cracking would occur during such period in the presence of the catalyst hereinafter specified, and then flowing said heated vapors through a mass of adsorptive catalytic material adapted to induce such rapid and efficient cracking Within said temperature range, and while the oil vapors are so owing within Asaid mass supplying enough heat thereto to more than compensate for that absorbed by the net endothermic cracking reaction and thereby raise the temperature of the oilr vapors during their flow through said mass by transfer of .heat from a multiplicity of symmetrically disposed streams of heating medium iiowing through but out of contact with the catalytic material so that the cracked vapors leave the mass at a temperature within said range appreciably above that of their entry thereinto.

3. The process of cracking the vapors of a mineral oil charging stock which comprises-heating the vapors to within a temperature range within which no efficient cracking occurs during said heating period but within which range rapid and ecient cracking would occur' during such .period in the presence of either of Vthe catalytic masses hereinafter specified,l and then flowing said heated vapors successively through a plu-v rality of cracking chambers, the catalyst in each chamber comprising afmass of adsorptive catalytic material adapted 'to induce cracking and while the vapors 'are so passing Within each cracking chamber so supplying heat thereto by transfer of heat from a multiplicity of symmetrically disposed streams of heating medium flowing through but out of contact with the catalytic material as to at least compensate for that absorbed by the net endothermic cracking reaction and -thereby prevent the reduction in temperature therein that would otherwise occur.

4. The process of cracking the vapors of a mineral oil charging stock which comprises heating the vapors to within a temperature range within which no eicient'cracking occurs during said heating period but within which range rapid and eiiicient cracking would occur during such period in the presence of either of the catalytic masses hereinafter specified, and then flowing said heated vapors successively through a plurality of cracking chambers, the catalyst in each chamber comprising a mass of adsorptive cata-..

lytic material adapted to induce cracking and while the vapors are so passing within each cracking chamber so supplying heat thereto by transfer of heat from a multiplicity of symmetrically disposed streams of heating medium flowing through but out of contact with the catalytic material as to somewhat more than compensate for that absorbed by the net endothermic cracking reaction so that the cracked vapors leave each chamber at a temperature Within s'aid range appreciably above that of their entry thereto.

5. The process of cracking the vapors of a mineral oil charging stock which comprises heating the vaporslto within a temperature range within which no ecient cracking occurs during said heating period but within which range rapid and eicient cracking would occur during such period in the presence of the catalyst hereinafter specined, then owing said heated vapors through a mass of adsorptive catalytic .material adapted to induce such rapid and efficient cracking within said temperature range and during the catalytic cracking operation flowing a heating medium through and in direct heat exchange relation, but out of contact, with the catalytic mass, said heating medium being at such temperature as to supply enough heat to the mass to at least compensate for the' heat absorbed by the net endothermic cracking reaction and traveling through the mass in the form of a multitude of fine closely associated independent streams distributed with substantial uniformity throughout the mass, whereby lall. parts of the `mass are heated with substantial uniformity and 'the cracked vapors leave the mass at a temperature not appreciably below the temperature of their entry into the 'maSS.

tion supplying enough heat to the catalyst while the oil vapors are nowing therethrough to com' pensate for that absorbed by the net endothermic cracking reaction by flowing substantially vertically through the catalytic mass, in direct heat conducting relation therewith but out of contact therewith, a heating medium in a multiplicity of closely associated and evenly distributed inde,- pendent flne streams so that all parts of the mass are heated with substantial uniformity and the cracked vapors leave the mass at a temperature within said range and not below the temperature of their entry into the mass.

7. In'a process for the chemical treatment or transformation of hydrocarbon fluid in the presence of solid porous adsorptive and incombustible contact material within a reaction space in which said contact material is alternately emmation of said hydrocarbon fluid and in regeneration in situ by passing a regenerating fluidtherethrough to effect removal of combustible deposits therefrom, the cycle of operation involvtiplicity of parallel vertical streams and thence through the contact material and thence flowing the transformed fluid in a multiplicity of parallel vertical streams within but out of contact with the bed of contact material, the vertical streams of each set being symmetrically -arranged at variing a period on stream and a period in regeneration being repeated over and over, the method of heat exchange and temperature control which comprises flowing each of said fluids, alternately one with the other, within but out of contact with the bed of contact material in a multiplicity able distances from the vertical center line of the bed and the streams of the two sets being so` symmetrically arranged .relatively to each other as to provide amultiplicity of paths of fluid flow through the bed of contact material between vertical inflow and outflow streams, that are spaced apart a distance short relative to the lateral dimensions of the contact bed, and si-A multaneously flowing a heat exchange fluid through the mass of contact material in direct heat conducting -relation, but out of contact with said contact material and at a temperature approaching that'which it is desired to maintain in said contact .material and deviating from the latter temperature substantially only to effect the desired amount of heat exchange therewith, the temperature of the heat-exchange fluid during the on-stream cycle being such as to lsupply enough heat to the mass to compensate for the heat absorbed by said net endothermic reaction, said heat exchange fluid being a material extraneous to said reactant and l'regenerating fluids and flowing vertically through the bed of contact material in a multitude of independent streams at variable distances from the center line of the bed and symmetrically arranged with respect to each other and to the vertically flowing fluidvinlet andoutlet streams, and subjecting the transformed vertical inflow and outflow streams that are spaced apart a distance short relative to the lateral dimensions of the contact bed, and si-' multaneously flowing heat exchange fluid through the mass of contact material in direct heat conducting relation but out of contact with said contact material and at a temperature ap'-v proaching that which it is desired to maintain in said contact material and deviating from the lathydrocarbon fluid to further reformation in another contact chamber in whichthe flow of such hydrocarbon fluid and the ow of a heatA exA change medium is the same as in the firstl chamber but in which the temperature of the heat exchange medium is sufciently high to maintain, in the contact mass a uniform temperatureabove that maintained in the first contact mass, thereby insuring in the second treatment the subjection of all the hydrocarbon fluid to a temperature above that to which it is subjected in the first treatment. ,v 1

9. In a process for the chemical treatment -or transformation of fluid hydrocarbon reactants :in the presence of solid porous'adsorptive and incombustible contact material within a reaction space in whichl said contact material is alter-4 nately employed on stream to effect the desired transformation of reactants with accompanying net endothermic reaction and in regeneration in l on stream anda period in regeneration being-retransformation of fluid hydrocarbon reactants in the presence of solid porous adsorptive and incombustible contact material within a reaction space in which said contact material is alterflowing each of said fluids within but out of contact with the bed of contact material in a' mulpeated over and over, the method 'of Vheat ex'.-l change and temperature control `which comprises flowing each of said fluids within but o ut of contact with the bed of contact material in a multiplicity of parallel vertical streams and thence through the contact material and thence flowing the transformed fluid in a multiplicity of parallel vertical-stream within but out of contact with the bed of contact material, the

vertical streams of each set being symmetrically arranged at variable distances from the vertical center line of the bed and the streams of the two sets being so symmetrically arranged relastreams that are spaced apart a distance short relative to the lateral dimensions of the contact bed, and simultaneously flowing heat exchange fluid through the mass of contact material in direct heat conducting relation but out of contact Withsaiducontact material and at a temperature approaching that which it is desired to maintain in said contact material and deviating from the latter temperature substantially only to eiect the desired amount of heat exchange therewith, the temperature of the heat-exchange uid during the on-stream cycle being such as to supply enough heat to the mass to compensate for the heat absorbed by said net endothermic reaction, the temperature of the heat exchange fluid during the regenerating cycle being such as to extract heat from the mass, said heat exchange fluid being a material extraneous to said reactant and regenerating uids and flowing vertically through the bed of contact material in a multitude of independent streams at variable distances from the center line of the bed and symmetrically arranged with respect to each other and to the vertically flowing fluid inlet and outlet streams.

ARTHUR E. PEW, JR.

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