US2375558A - Mixing apparatus - Google Patents

Description

A. J. L. HUTCHINSON MIXING APPARATUS May 8, 1945.

Filed April 9, 1945 2/ #rover/waan J/vz Er REW/r1. fluff f 4 /46/0 INAH i l MPMaJIMIw/z IN V EN TOR.

Patented May 8, 1945 3 Vv2,375,558A4 t I MIXING APPARATUS I Arthur LfHutchinson, Los Angeles,"Calif., ass'gnorto `The Fluor Corporation, Ltd., Los Angeles, `Ca`lii'.,"a` corporation of California v Application' pril 9, 1943, Serial No. 482,405

` ,comme (c1. 25a-e235 This invention deals `generally Withmixingtapparatus ofthe .type in whichuid -is introducedto a `revolving-"agitator or rotor, and is ejected `in iinely divided condition through apertures in the rotor into a surrounding `body of liquid In -cer o tain of itsmore particular aspects theinvention is directed to the use ofsuch rotor. type mixers, for intimately Acontacting chemically reactive I materials and meetingthe thermal requirementsof` the mixing operation by heating or cooling, `as the case may be, the reactingmixture;

It is contemplated that the invention may be employed for mixing or contacting any materials for. which the apparatus is adaptable,"` and that such materials may include liquid` or `gaseous fluids, with or without solids being included in the mixture. 'Ihe invention has been designed partieularly for use as a catalyst contactor info-i1 refining processes, especially for alkyl'ation of hydrocarbons in the presence of an -acid catalyst, and will thereforebe described typically in connection with such uses. Y I Y I The general procedure employed in methods of alkylation, involves contacting afmixture of hydrocarbons,` e. g., olefins and isoparafllns, with an acid catalyst such as sulphuric acid, which prouisites and consequences of ltheir forming a chemically: reactivemixture,` handling and mixing of the` materials present diiliculties and requirements for ,most eilicientloperationgthat are not `met togbest advantage by ordinary mixers.

Among the major features to be desired in a mixer of this kind, are such control over the proportions,

Well as thorough agitation of lthe resultingmx-` ture,and provides for ecienttransfer of heat between the mixture and a surrounding exchanger unit placed in direct contact with the agitated mixture. For'purpo'ses of alkylation, separate I streams ofthe hydrocarbons and acid, or catalyst,

physical condition and distribution ofthe `reactants as to avoidexcessive effects of oneon the other, and to favorably promote the desired comation contactor by providing for the eiiicient'removal of heat `from the mixture directly Within the mixing zone. From standpointsj` of equipment expense and operating `costs itis ldesirable that the apparatus beV of simple` construction, thoroughly practicable `for installation, repair and replacement of parts, and that power costs, pressure drops and the like, `be minimized `tothe greatest extentcompatible with thorough mixing;

In accordance with the invention, these features are embodied in mixingV Aapparatus which utilizes a motor-driven rotor for obtaining initial division avoided, and general uniformity of admixture `and reaction are assured.` Then by providing for direct heat" exchange with" theA agitated mixture, close and eiicient control is had upon the thermal conditions of thereaction'. I I

Included among additional objects andfeatures of the-invention are such structural improvements as the maintenance of a seal preventing access of corrosive fluids tothe motor shaft; packing joint, the simplicity of construction and mounting of the heat exchange unit Within the mixing chamber, and the provisionlfor baffledxflow of thereacted mixture fromthe mixing zone to itsoutlet.

More complete understanding of all the features and objects of the invention, as Well as thedetails of certain typicaland illustrative embodiments, will be had from the description to follow. `Relerence is had throughout the description tothe accompanying drawing in which:` I I Fig, l *is a view showing one form of the mixing apparatus in vertical section; 3 I

I Fig.2'lis a fragmentary sectionon line 2-2 of Fig.1; l I

Fig. 3 `is a introduced through the inlet 22 is taken intofthe I rotor, as will `later appear. The packing joinf-l 23 provides a seal against uid leakage from passage y 2l up-Wardlyalong the rotor shaft,`

I A rl'lhe mixing chamber I`f`I containsa `vertically and dispersion of the materialsftobeimixed, as 55 cxtehdingrotorfgenerally indicated *at =24,"0f I view simnar to Fig. 1, `i11usnaung a .variational form of the inventionyand` f hollow construction and preferably frustro-conical in shape, substantially as illustrated. The

top portion 25 of the rotor shell 26 projects into the lower end of the cover plate bore I9 to restrict or largely eliminate the passage of fluid from space 2l downwardly about the rotor, and to confine the fluid delivery to the rotor through space 21 about the shaft 2D. The lower end 28 of the rotor may approach more or less closely the stationary inlet 29 through which an independent fluid stream is introduced to the lower section of the rotor. Displacement of fluid from the mixing chamber il to the top end of the rotor is restricted and largely prevented by an annular baille 30 attached to the cover i5 and extending in close proximity to the surface of the rotor. Further upward displacement of acidic mixing chamber fluid that might be injurious to the packing joint 23, is prevented by the close running of the top end 25 of the rotor Within bore i9, and the maintenance of the oil seal resulting from the hydrocarbon fed to the rotor through passage 2i.

The rotor may be mounted on its drive shaft 26 in any suitable manner, as for example by securing the lower end of the shaft at 3l within the rotor partition 32, and by a spider attachment 33 of the shaft within the upper end 25 of the rotor. The shaft is suitably journaled and supported above the packing joint 23, as by the conventionally illustrated radial bearing 34 and the combined radial and thrust bearing assembly 35, above which the shaft may connect with a motor, not shown, operating to turn the rotor at suitable speed, say in the neighborhood of 300 R. P. M.

The,rotor is surrounded by a heat exchange assembly, generally indicated at 36, which, broadly speaking, may be of any suitable form and construction presenting heat transfer surfaces in direct exposure within the mixinglchamber to the body of liquid undergoing mixing agitation by the rotor. In the form of the invention shown in Fig. 1, the heat exchange assembly 36 comprises a circular arrangement of depending closed end tubes 31 extending upwardly through openings 38 in the shell l0 and terminating within an annular channel 39. The tubes 36 contain iluid delivery tubes illy extending upwardly through channel 39 to terminate within the top channel 4I, the latter containing plugs 4,2 which are removable to permit access to the tubes. Cooling fluid or refrigerant introduced to channel 4i through one or more inlets 43, passes downwardly through tubes 40 and thence flows upwardly within tubes 31 to the outlets 44. By this arrangement, the refrigerant is maintained in a condition of flow permitting elcient transfer of heat from the reacting mixture inchamber il through large tube surface areas in direct exposure tothe liquid mixture being lagitated by the rotor. The rotor is provided with suitable outside vanes for purposes of agitation and iluid circulation, the vanes preferably being in the form of a spiral 45 acting to displace the liquid upwardly in the vicinity .of the rotor, and to thereby cause fluid circulation at substantial velocity downwardly along the surfaces of the tubes 31. f

The reacted mixture is taken from the cha ber IlL through an outlet 46 positioned in an upper location in the shell I at the outside of an annular baille 41 spaced at 48 from the wall of the shell. The presence of baille 41 removes the mixture flowing to the outlet, from the more violent state of agitation existing within the central portion of the chamber, and permits, where the ocasion may require, settling out of emulsions or solids to be retained in the mixing chamber. Auxiliary connections 48 and 49 in the bottom of the chamber may be employed as independent inlets or outlets, as for the introduction or removal of fluid, or of solid catalyst to be included in the mixing.

The form of the invention shown in Fig. 3 differs from the described embodiment with respect to the particular forms of the heat exchanger assembly 50 and associated parts. Here the exchanger comprises an annular, closed bottom shell 5l having spaced walls 52 terminating in the lower channel 53. Refrigerant introduced to I the upper channel 54 through inlets 55 is discharged through tubes 56 into the bottom of the shell 5l, the refrigerant then flowing upwardly to the `outlets 51. Vertically extending vanes 58 may be carried by the inside of the shell 5| to maintain the mixture being circulated by the rotor, in substantially straight line flow along the surface of the exchanger. The vanes thus prevent bodily rotation of the liquid `mixture with the rotor (i. e., at any speed approaching that of the rotor) a purpose also served by the exchanger tubes in the form of Fig. 1,by reason of the effect of the individual tubes 31 in baffling circular llow of the'agitated body of liquid. The mixture flowing through space 59 to the outlet .60 may be similarly baffled or directed `by the outside vanes 6I, it being noted that the shell 5I serves both` as an exchanger and an annular baille between the mixing chamber proper and the outlet 60.

In operation, the hydrocarbons, e. g., an oleiin-isoparaffin mixture, is fed through inlet 22 into the upper rotor chamber 62 above the partition 32. The acid catalyst, e. g., sulphuric acid, enters the lower rotor chamber 63 through the bottom inlet 29. The two streams are reduced to states of ne division and are intimately dispersed into the liquid mixture being agitated by the rotor in chamber ii, by ejection' through' slots 65 in the rotor. In this manner, the streams are prevented from co-mingling in advance of their dispersion into the mixture, at which point the materials are so divided and distributed as to obviate any possibility of over-reaction resulting from excessive concentrations of vthe acid in the presence of the hydrocarbons. The reaction of the hydrocarbons being exothermic, it is important that provision be made of constant and efcient removal of heat from the reacting mixture. Heat also is developed by the conversion of the mechanical work energy of the rotor, and

it is desirable that such mechanically created heat be removed. Heat removal from the mix-v ture is accomplished by the heat exchanger, by virtue of its surrounding relation to the rotor, and the turbulence and velocity of the uids inside and outside the exchanger surfaces. i

As previously indicated, the mixing apparatus may be employed for lolending or mixing fluids, one of which may be a gas. In such instances, a gas or vapor may be introduced through one of the inlets 22 or 29, and a liquid through the other inlet. Solid pulverulent material such as a catalyst, may be introduced with the fluid, or independently as through one of the connections 43 or 49. As al specific example of a purpose for which a liquid or liquid mixture may be contacted with agas, the apparatus may be used for the conversion of such low molecular weight gases as methane, ethane `and propane, to their solid hydrates by contacting the gas with water under controlled temperature and pressure con-` ditions. The hydrocarbon gas may be introduced through one cf the inlets 22 or 29, and water or By maintaining the chamber under the pressures and temperatures at which the hydrates are known to form, the hydrocarbons are `converted to solid hydrates which may be removed with any excess water, or in the carrier oil, through the outlet 46. The water, or waterand carrier oil, may be precooled to the conversion temperature before introduction to the mixing cham-` ber, and refrigerant circulated through the exchanger 36 to remove the heat of hydrateformation, or the entire cooling of the fluids and removal of the heat of hydrate formation may be effected Within the mixing chamber `by transfer of heat to the exchanger.

The described apparatus may serve also as an efficient contactor for cold acid treatment of hydrocarbons, mixing of the oil and acid, and cooling of the mixture to maintain low temperature conditions, occuring in a, mannersimilar to alkylating treatment of hydrocarbons, as previously described.

I claim:

1. Mixing apparatus comprising a mixing chamber, a vertically extending rotor Within the chamber, means for rotating said rotor, means for feeding linto the rotor a stream of fluid that is ejected through apertures inthe rotor and dispersed in finely divided form into an agitated body of liquid in said chambenheat exchange means contacted by said agitated body of liquid at the outside of the rotor and passing heat con-` ing a mixing chamber, a rotor within said chamber rotatable about` a vertical axis, a rotor shaft extending through the top wall of said chamber, means for rotating said shaft and rotor, a packing joint for preventing fluid leakage from the chamber upwardly along the shaft, means introducing fluid at a location belowY said pack- `ing joint into the top of the rotor, the fluid thence being ejected through apertures in the rotor into a body of liquid in said chamber, means for introducing uid into the bottom of the rotor, means for ejecting the last mentioned fluid into said liquid body through apertures in the rotor separately from the rst mentioned fluid, heat exchange means supported by said top wall of the chamber and surrounding said' rotor for passing heat conductive iluid in indirect heat transferring relation with said body of liquid, a baille surrounding said heat exchange means and spaced from said shell, and an outlet to which liquid liows upwardly from said body at the outside of the baiile.

3. Mixing apparatus comprising a mixing chamber, a rotor within the chamber, means for rotating said rotor, means for feeding :into the rotor a fluid stream that is thence ejected through `one set of. apertures in the rotor to disperse the fluid into an agitated body of liquid in said chamber, means for introducing a second fluid stream into the rotor and thence through a second set of apertures in the rotor into said f chamberfor admixture with said body of liquid, means for maintaining said body of liquid in direct Contact with the rotor and at a level above the location at which said fluid is ejected from the rotor into the liquid, heat exchange means chamber, a rotor within the chamber, means for rotating said rotor, means for feeding separate' into the upper rotor chamber, the uid thence being ejected through upper apertures in the rotor into a body of liquid in said Zone, means for introducing `iiuid into the lower rotor chamber to be ejected separately from `the iirst mentioned iluid through lower apertures in the rotor into said body of liquid, and agitator vanes carried by the outside of said rotor.

` ARTHUR J. L. HU'ICHINSON.

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