Title:
Apparatus for alkylation
United States Patent 2453837
Abstract:
The present invention relates to alkylation and particularly to alkylation of isoparaffinic 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 alkylation...


Inventors:
Fisher, Edward J.
Franklin, William B.
Smith, Delmas A.
Application Number:
US50631643A
Publication Date:
11/16/1948
Filing Date:
10/15/1943
Assignee:
STANDARD OIL DEV CO
Primary Class:
Other Classes:
422/647, 422/648, 585/730
International Classes:
B01J14/00; B01J19/24; C07C2/62
View Patent Images:
Foreign References:
DE228544C
Description:

The present invention relates to alkylation and particularly to alkylation of isoparaffinic 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 alkylation reactions.

In the prior art teachings of the alkylation of isoparaffins 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 18 of isoparaffins to olefins charged to the process.

It has generally been understood that a high ratio of isoparaffins to olefins is conducive to obtaining good results. However, it has been found that maintenance of high external isoparaffin-olefin 21 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 2 emulsion recycle ratio is by the internal isoparaffin-olefln ratio concept. The internal isoparaffin-olefin ratio is calculated from the amount of isoparaffin and olefin in the fresh feed to the reactor and the isoparaffin contained in the recycle 3 emulsion at the point where the fresh feed and recycle emulsion are mixed. Thus the ratio of the total amount of isoparaffin in both the feed and emulsion streams to an alkylation reactor to the amount of olefln charge thereto is called the internal isoparaffin-olefin ratio.

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

Another object of our invention is the provisioli 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 II designates a relatively elongated vertical cylindrical vessel closed at both ends and divided by internal partitions 12 and 13 into three compartments 14, 15 and 16, respectively. The top compartment 14 has projecting into it an L-shaped pipe 17 which is positioned so that it will deliver fluid into a downpipe 18.

pAt an intermediate point in compartment 14 inlet 19 is provided for introduction of emulsion.

At a lower point in compartment 14 there are arranged radially on internal header 20, jets 21 for distribution of emulsion upwardly into compartment 14.

Down-pipe 18 projects through partition 12 and terminates in a distributor 22 located in the i top portion of compartment. 15. Distributor 22 is provided with jets 23 equally spaced thereon which allow distribution of the material flowing downwardly through down-pipe 18 from compartment 14.

0 Adjacent to the bottom of compartment 15 and partition 13 there is provided an L-shaped pipe 24 by means of which olefinic hydrocarbons are introduced.

As mentioned before, partition 13 divides vessel 11 into compartments 15 and 16. Partition 13 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.

0 The elongated vertical vessel I I is also provided with outlets 27 and 28 for removal of product and recycling of emulsion, respectively.

Down-pipe 18 and the inlet to distributor 25 are provided with orifice plates 29 and 29' for 35 preliminary mixing of 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 4o 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, isoparaffins, and acid are admitted by 45 lines 30, 31, and 32, respectively, into line 33 where the three streams admix with emulsion withdrawn from reactor II. The emulsion of olefins, isoparaffins, and acid in line 33 pass into line 34 where the mixture is divided into two parts. One 50 portion is circulated by pump 35 to the top com2,4J 3 partment 14 of reactor II by way of line 36 which is connected to header 20; the other portion is circulated by way of pump 37 after cooling in emulsion cooler 38 to compartment 14 to which line 34 connects through inlet 19.

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 14 through L-shaped pipe 1T. Connected to line 30 is a second line 40 for introduction of olefins into compartment 15 by means of an L-shaped line 24.

There is withdrawn from the top of reactor I I an emulsion of hydrocarbon and acid by way of line 41 which connects to acid separator 42. Acid separator 42 is of sufficient capacity to allow resolution of the emulsion into its component parts of acid and hydrocarbon by gravity separation. Hydrocarbon product containing alkylate and unreacted hydrocarbon is 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 2 45 in branch line 46. Fresh. acid is introduced into the system, to replace the spent acid withdrawn, by opening valve 47 in branch line 48. rn an.operation utilizing the improved apparatus of our invention-the olefins discharging into compartment 14 by way of L-shaped line 17 jet 3 downwardly through down-pipe 18 along with emulsion overflowing thereto, the emulsion in compartment 14 being introduced by recycling emulsion from compartment 16 through pumps 35 and 37, and lines 36 and 34, connecting with jets 21 and inlet 19, respectively. The emulsion flows downwardly with increased velocity through down-pipe 18 and through jets 22 into compartment. IS in the manner described and is reacted with olefins in compartment 15 by introduction of additional amounts of olefins by L-shaped pipe 24: The combined reformed emulsion jets downwardly with no substantial decrease in velocity into compartment 16 through jets 26 and the emulsion leaving the vessel 11 by outlet 28 is cir- 45 culated in-the manner described to the top compartment 14. The top compartment 14, from which product is Withdrawn through outlet 27, has a relatively quiescent zone in the top portion thereof which 50 is out of. the main flow of fluid. The material withdrawn by outlet 27 comprises reacted hydrocarbons. and acid which are separated in separator 42' as described.

Vessel 1 was employed to alkylate isobutane 55 and butylenes in an operation in which sulfuric acid of 93.8% strength was employed at a reaction temperature of 466 F. and a contact time of 35 minutes with a hydrocarbon retention time per pass of about 2 minutes. 60 The total fresh feed had the following analysis: Table I Per cent Propane --------------------------------- 3 65 Butylenes------------------------------ 6.4 Isobutane ----------------------------- 52.5 Normal butane -------------_----------- 38.1 This hydrocarbon mixture was alkylated in the apparatus of our invention under conditions set 70 forth in the preceding paragraphs to obtain an alkylate having an octane number of approxi- i mately 93 determined by the A. S. T. M. motor I method; The alkylate produced was obtained under conditions such that an internal isoparaffin 75 r 53,837 to olefin ratio of 358, 391 and 391 were maintained in the compartments 14, 15, and 16, respectively, of the elongated vessel 11. The internal isoparaffin-olefin ratios were calculated from the following operating conditions on a commercial size alkylation reactor in accordance with the present invention.

Table II 10 ~----Com- Corn- Compart- part- partment ment ment 14 15 10 Emulsion, gal./min ---...-.------ 12 750 12, 750 12,750 Hydrocarbon in recycle stream, gal./min. 7,057 7,058 7,058 Total fresh feed, gal./min..---------------- 379 408 408 Recycle hydrocarbon, gal./min.... --- ---- 6,678 6,650 6,650 Isoparaffin recycle, gal./min .--------- 3,127 3,105 3,105 Isoparaffin in fresh feed, gal./min .... 208 206 20 Total isoparaffins, gal./min--------- 3,335 3,36 3,3 olefins, gal./m in ------ 9.3 8.5 8.5 Internal ratio, isoparaffins/olefins .-- --- 358 391 391 0 Internal ratio (Overall) --.--......----. 125 Thus it can be seen from the above figures that by operating with the apparatus in accordance with the present invention, high internal ratios Swere maintained during the reaction. These high internal ratios were maintained irrespective-of the external ratio which in the particular operation in question averaged 8.3.

The embodiment of our invention used to carry 0 out the operation described above was as shown in the drawing. The dimensions of the elongated vertical vessel II were 10 by 48 feet. The compartments 14, 15, and 16 were each approximately 1/3 of the over-all length. The down-pipe 5 18 connecting header 22 with compartment 14 was 24 inches in diameter and extended into compartment 14 to a height of 12 feet. In the operation utilizing the present apparatus 1/3 of the olefins were injected into the reactor by way of lines 39; /3, by way of line 40; and 1/3, by way of lines 33, 34 and 36, which in turn connect with compartment 14 of vessel. 1.

The dimensions of L-shaped pipes 1T and 24 and the outlets 27 and 28 will vary depending on the amount of charge, emulsion, and product either introduced or withdrawn from the vessel II. 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 1 was maintained by external refrigeration of the stream-of emulsion entering the compartment 14 by way of line 34 and coolers 38. However, the type of refrigeration employed in the apparatus of our invention is immaterial since either indirect or direct refrigeration may be employed. In some instances it may be desirable to use both types of refrigeration.

The amount of acid introduced into the system by way of line 48 and withdrawn by way of line 46 is not given herein since this figure is dependent on the amount 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 invention and maintenance of acid strength is well-known to the art. In the apparatus of our invention it is desirable to adjust the conditions during the operation thereof so that an internal isoparaffinolefin ratio of between 30 and 500 is maintained n each of the several compartments described.

Preferably the overall internal-ratio should be vithin the range of 50 to 200; theĆ½ overall.internal *atio is obtained by dividing:the-average figure for total isoparaffins by the total of the olefins introduced to each compartment of the apparatus of our invention, the assumption being made that all of the oleflns were introduced into line 33.

The maintenance of the internal ratios should be coupled with maintenance of external ratios of approximately 6-12:1 with a 15 to 25 pounds per square inch pressure drop across each of the jet header assemblies 20, 22 and 25.

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 ol 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 saic openings into said upper compartment, and ai outlet located in the upper end of said uppe: 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 inter0 mediate 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 ,o 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 5, 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 compart:" ment, 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 1,684,489 1,952,482 2,080,737 2,184,838 50 Number 228,544 Name Date Halloran --------- Sept. 18, 1928 Whitaker ---------- Mar. 27, 1934 Nutt, et al. --------- M May 18, 1937 Hooker, et al. ------- Dec. 26, 1939 FOREIGN PATENTS Country Date Germany---------- Nov. 10, 1910