US2453837A - Apparatus for alkylation - Google Patents

Description

Nov. 16, 1948. E J.' FISH'EIQ r AL I 2,453,837

APPARATUS FOR ALKYLATION Filed Oct. 15, 1945 Product Spent 5 Acid 39 O 44 53/ I 2 Olefins lsoporqffin Cooler v 52 Recycle Acid f) I 37 Q 35 pg J A OQMQ INVENTORS ATTORNEY.

fig MM Patented Nov. 16, 1948 APPARATUS FOR ALKYLATION Edward J. Fisher and William B. Franklin, Baytown, Tex., and Delmas A.

Standard Oil Development Company, a corporation of Delaware D. 0., assignors to Smith, Washington,

Application October 15, 1943, Serial No. 506,316

The present invention relates to alkylation and particularly to alkylation of isoparaflinic hydrocarbons with olefinic hydrocarbons in the presence of a liquid catalyst such as sulfuric acid. More particularly, this invention is concerned with an apparatus for carrying out liquid'phase alkylationreactions. r

;In the prior art teachings of the alkylation of isoparaflins with olefins it has been customary to conduct the reaction in an emulsion of the hydrocarbons with the sulfuric acid catalyst. One measure of successful alkylation is maintenance of external ratios of isoparaffins to olefins of the order of about 6 to 12: 1 and even higher. By external isoparaffin-olefin ratio is meant the ratio of isoparaffins to olefins charged to the process. It has generally been understood that a high ratio of isoparafiins to olefins is conducive to obtaining good results. However, it has been found that maintenance of high external isoparaflin-olefin ratios alone is not a satisfactory basis for indication of successful operation since it does not take into account the important variable of emulsion recycle ratio. A satisfactory method of combining the external isoparaffin olefin-ratio and the emulsion recycle ratio is by the internal isoparaflinolefin ratio concept. The internal isoparafiin-olefin ratio is calculated from the amount of isoparafiin and olefin in the fresh feed to the reactor and the isoparaffin contained in the recycle emulsion at the point where the fresh feed and recycle emulsion are mixed. Thus the ratio of the total amount of isoparafiin in both the feed and emulsion streams to an alkylation reactor to the amount of olefin charge thereto is called the internal isoparaffin-olefln ratio.

It is one of the objects of our invention to provide an improved apparatus for isoparafl'in-olefin alkylation which allows maintenance of very high internal ratios of isoparafiin to olefin irrespective of the external ratio.

Another object of our invention is the provision of apparatus which allows reforming of the emulsion during the reaction whereby improved results are obtained.

In the drawing, the single figure shows a preferred form of the apparatus of our invention in sectional elevation.

In the drawing numeral ll designates a relatively elongated vertical cylindrical vessel closed 2 Claims. (01. 23 235) at both ends and divided by internal partitions l2 and I3 into threecompartments l4, l5 and I6, respectively. The top compartment l4 has projecting into it an L-shaped pipe H which. is positioned so that it will deliver fluid into a down: pipe l8. 1

' At an intermediate point in compartment I! inlet [9 is provided for introduction of emulsion. At a lower point in compartment l4 there are arranged radially on internal header 20', jets 2| for distribution of emulsion upwardly into compartment l4.

Down-pipe l8 projects through partition l2 and terminates in a distributor 22 located in the top portion of compartment. l5. Distributor 22 is provided with jets 23 equally spaced thereon which allow distribution of the material flowing downwardly through down-pipe [8 from compartment l4. 1

Adjacent to the bottom of compartment l 5 and partition l3 there is provided an L-shaped pipe 24 by means of which olefinic hydrocarbons are introduced.

As mentioned before, partition l3 divides vessel ll into compartments l5 and [6. Partition I3 is provided with a depending distributor 25 on which there are arranged equally spaced jets 26 for distribution of the material flowing downwardly from compartment 15 to compartment 16.

The elongatedvertical vessel l l is also provided with outlets 21 and 28 for removal of product and recycling of emulsion, respectively.

Down-pipe i8 and the inlet to distributor 25 are provided with orifice plates 29 and 29. for preliminary mixing 0 the streams flowing therethrough.

The manner in which this preferred form of apparatus is to be employed in carrying out an alkylation reaction will now be described with references to the drawing, the flow lines, hereinafter referred to, all being connected to vessel II at points the exact location of which appear in the drawing.

' Olefins,'is0parafiins, and acid are admitted by lines 30, 3|, and 32, respectively, into line 33 where the three streams admix with emulsion withdrawn from reactor I I. The emulsion of olefins, isoparafiins, and acid in line 33 pass into line .34 wherethe mixture is divided into two parts. One portion is circulated by pump 35 to the top: compartment l4 of reactor H by way of line 36 which is connected to header 20; the other portion is circulated by way of pump 31 after cooling in emulsion cooler 38' to compartment l4 to which line 34 connects through inlet I9.

Line 30, by means of which olefins are introduced into line 33, is provided with a branch line 39 by means of which olefins are injected into compartment [4 through L-shaped pipe l1. Connected to line 30 is a second line 40 for introduction of olefins into compartment I by means of an L-shaped line 24.

There is withdrawn from the topof reactor H an emulsion of hydrocarbon and acid by way of line 4| which connects to acid separator 42. Acidseparator 42 is of sufficient capacity to allow resolution of the emulsion into itscomponent parts of acid and hydrocarbon by gravity separation. Hydrocarbon productcontaining alkylate and unreacted hydrocarbonis withdrawn from. the acid separator 42 through line 43'; while acid is discharged from the separator 42 through line 44 connecting to line 32. A portion'of the acid discharged from the separator 42 by line 44 may be withdrawn from the system by opening valve 45 in branch line 46. Fresh. acid is introduced into the system,.to replace the spent acid withdrawmbyopening valve 41 in branch line 48;

In anoperation utilizing the improved apparatus of'our inventionthe olefins disch'argin'g'into compartment l4'by way of L-shaped line i! jet downwardly through down-pipe I8 along with emulsion overflowin thereto, the emulsion in compartment 14 being introduced by recycling emulsion from compartment I 6 through pumps 35"and 3'1 and lines 36 and 34, connecting with ets 2'! and inlet l9, respectively. The emulsion flows downwardly with increased velocity through 'down.-pipe l8. and throughjet's 22 into compartment. lfiin the manner described and-is reacted with olefins in compartment l5 by introduction of additional amounts of olefins by L-shaped pipe 241 The combined reformed emulsion jets downwardly with no substantial decrease invelocity into compartment l6 through jets 26 and the emulsion leaving the vessel H by outlet 28'is circulat'ed inthe manner described to the top coinpartment' I4:

The top compartment I4, from which product i's'withdrawnthrough outlet 21, has a relatively quiescent. zone in the top portion thereof which is outof. themainfi'owfof fluid. The material withdrawn by'outl'et 21 comprises reacted hydrocarbons. and acid which are separated inseparator 42' as described.

. Vessel II was employed toalkylate isobutane andbutylenes in an operation in which sulfuric acid of 93.8% strength was employed at a reaction temperature of 46 F. and a contact time'of 35 minutes" with a hydrocarbon retention time per pass" of about 2 minutes.

The total fresh feed had the following analysis:

Table I Per cent Propane 3 Butylenes 6.4 Isobutane r 52.5 Normal butane 38.1

This hydrocarbon'mixture was alkylated in the apparatus of our invention under conditions set forth in" the precedlngiparagraphs to obtain an alkylate having an octane number of approxin'iat'ely'93 determinedby the A. S. T. M. motor method; The alkylate produced was obtained underconditicns s'uclrthat aninternal isoparaifin 4 to olefin ratio of 358, 391 and 391 were maintained in the compartments l4, l5, and [6, respectively, of the elongated vessel H. The internal isoparaihn-olefin ratios were calculated from the following operating conditions on a commercial size alkylation reactor in accordance with the present invention.

Table II Oom- Oon1- Compartpartpartment ment ment Emulsion, galJmin 12, 750 12, 750 12, 750 Hydrocarbon in recycle stream, gal./Inin 7, 057 7, 058 7, 058 Total fresh feed, gaL/min. 379 408 408 Recycle hydrocarbon, gaL/min 6, 678 6, 650 6, 650 Isoparaflin recycle, gal./min 3, 127 3, 3, 105 Isoparafiin in fresh feed, gaL/min 208 206 206 Total isoparafiins, gaL/min 3, 335 3, 311 3, 311 Olefins, gal/min 9. 3 8. 5 8. 5 Internal ratio, isoparaffins/olefins 358 391 391 Internal ratio (Overall) Thus it can be seen from the above figures that by operating with the apparatus in accordance with the present invention, high internal ratios were maintained during the reaction. These high internal ratios were maintained irrespectiveof the external ratio which in theparticular operation in question averaged 8.3.

The embodiment of our invention-used to carry out the-operation described above-was as shown in the" drawing. The dimensions of the elongated vertical vessel I l were 10 by 48 feet. The compartments I 4, l5, and I6 wereeach approximately of the over-all length. The down-pipe l8 connecting header. 22 with compartment l4 was 24 inches in diameter and extended into compartment l4 to a height of 12 feet. In-the operation utilizing the present apparatus ofthe olefins were injected into the reactor by way of lines 239; by way of line-40; and ,-by way of lines 33; 34 and 36, which in turn connect with compartment l4 of'vesselll..

The dimensions of L-shaped-pipes. Hand 24 and the outlets 21 and 28 will vary depending on the amount of charge, emulsion, and product either introduced or withdrawn from the vessel H. Stating this in another way, the dimensions of the inlets and outlets to'the vessel II are a function of the unit through-put.

The temperature of: the vessel H was maintained by external refrigerationof the stream-of emulsion entering the compartment I4 by way of line 34 and coolers 38. However, the type of refrigeration employed in' the apparatus ofour invention is immaterial-since either indirect; or direct refrigeration may beemployed. In some instances it may be desirable-to use both types of refrigeration.

The amount of acid introduced intothe system byway of line 48 and-withdrawn by way of line 46 is not given herein sincexthis figure. is dependent on theamount of olefin charged and-the level at which it'is desired to maintain the-strength of acid circulating in the system. Furthermore, this is not a critical feature of our inventionand maintenance of acid strength is well-known to the art.

In the apparatus of our invention it is desirable to adjust the conditions during theoperation thereof so that an internal isoparafiinolefin ratio of between 30 and 500v is. maintained in each of the several compartments described. Preferably the overall internal ratio should be Within the range of 50 to 200; the overallinternal ratio is obtained by. dividingtheaverage figure tor It will be understood that the apparatus and mode of operation described may be modified within the scope of our invention. Our invention is not limited by any of the embodiments which are understood to be given strictly by way of illustration and not by way of limitation. Manifestly, the apparatus is adapted for use in any reaction between liquids where a circulating stream of reaction mixture is maintained and it is desired to control time of contact between the reactants.

The nature and objects of our invention having been fully described and illustrated, what we wish to claim as new and useful and to secure by Letters Patent is:

1. An apparatus for conducting reactions between a plurality of liquid reactants while maintaining a circulating stream of reactants in the form of an emulsion which comprises a closed vessel, horizontal spaced partitions disposed within said vessel and dividing it into an upper compartment, at least one intermediate compartment, and a lower compartment, a, down pipe having an open upper end extending from an intermediate point in said upper compartment through the first partition and into a distributor having a plurality of restricted downwardly directed openings below said first partition, and in said lower compartment another distributor having a plurality of restricted downwardly directed openings, and being constructed and arranged so that it is in communication with the intermediate compartment, a conduit arranged to discharge a liquid reactant downwardly into the top of said down pipe, a distributor located below the opening of said down pipe in said upper compartment having a plurality of upwardly directed restricted openings, a conduit connecting said last named distributor with the lower compartment for recirculation of the liquid therein back through said openings into said upper compartment, and an outlet located in the upper end of said upper compartment.

2. An apparatus for conducting reactions between a plurality of liquid reactants while maintaining a circulating stream of reactants in the form of an emulsion which comprises a closed vessel, horizontal spaced partitions disposed within said vessel and dividing it into an upper compartment, at least one intermediate compartment, and a lower compartment, a down pipe having an open upper end extending from an intermediate point in said upper compartment through the first partition and into a first distributor having a plurality of restricted downwardly directed openings below said first partition, and in said lower compartment a second distributor having a plurality of restricted downwardly directed openings and being constructed and arranged so that it is in communication with the intermediate compartment next above, a first conduit arranged to discharge a liquid reactant downwardly into the open end of said down pipe, a third distributor located below the opening of said down pipe in said upper compartment and having a plurality of upwardly directed restricted openings, an outlet passing through the wall of the vessel at the lower end of the lower compartment, a second conduit connecting said third distributor with said outlet for recirculation of the liquid from the lower compartment back through said openings into said upper compartment, an inlet passing through the wall of said vessel into the upper compartment, and a third conduit having a cooling means arranged therein fluidly connecting said outlet with said inlet.

EDWARD J. FISHER. WILLIAM B. FRANKLIN. DELMAS A. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,684,489 Halloran Sept. 18, 1928 1,952,482 Whitaker Mar. 27, 1934 2,080,737 Nutt, et a1 May 18, 1937 2,184,838 Hooker, et al Dec. 26, 1939 FOREIGN PATENTS Number Country Date Germany Nov. 10, 1910

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