US2377937A - Stirring and mixing device - Google Patents

Description

June 12, 1945. s. 1.. HERVERT 2,377,937

STIRRING AND MIXING DEVICE Filed Sept. 24, 1942 2s ;h .3' 3o l 3| F a 3| I I as a as GEORGE L H VERT I, BY I I ATTORNEY Patented June 12, 1945 STIRRING AND MIXING DEVICE George L. Hervert, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., corporation of Delaware Application September 2 4, 1942, Serial No. 459,531

2 Claims. (Cl. 259-96) This invention relates to an improved form of apparatus of the class of mixing and stirring devices and the like, driven by electrical means such as an induction motor.

One of the primary objects of the invention is to provide an apparatus of this general class wherein the contacting or mixing zone may be operated at sub-atmospheric or superatmospheric pressure and in which packing means for preventing leakage past moving parts of the apparatus to or from the mixing zone are obviated.

Another object of the invention is to provide such an apparatus wherein the transfer of heat between the motor and the mixing zone is minimized.

The features of the invention are particularly advantageous as applied to apparatus for conducting contact conversion reactions at superatmospheric or sub-atmospheric pressure and at controlled temperature in a confined zone wherein agitation or mixing of the reactants with each other and also, when desired, with a catalytic agent for promoting the reaction is accomplished by mechanical agitation or stirring of the reacting mass maintained in said confined zone.

The catalytically promo-ted alkylation between saturated and unsaturated hydrocarbons is an example of an operation of the class above mentioned to which the features of the invention have been advantageously applied. In this particular process an alkylating agent, such as sulfuric acid, aluminum chloride, hydrogen fluoride or the like, is employed and is thoroughly mixed in the reaction zone with the reactive unsaturated and saturated hydrocarbons, such as, "for example, butylenes and isobutane. The reaction, being endothermic, results in a considerable evolution of heat and the temperature at which the reaction can be most advantageously conducted is rather critical. It is also desirable, if not essenof deflecting vanes 8 secured to and suspended tial, to keep the reacting mixture in liquid state from the removable head 4 by bolts 9. The imor in a dense phase resembling liquid state and peller I is mounted on a rotatable shaft H! exthis necessitates the use of relatively high prestending through the closure member 4 to the sure in the reaction zone; armature I l of the motor. Shaft I0 is journalled The invention, as embodied in an apparatus for within the mixing vessel'in a suitable bearing l2 conducting the alkylating reaction and other redisposed within housing [2' secured to the deactionsof this general class, provides an impeller tachable head 4. within the confined reaction and mixing 'zone for In accordance with the features of the invenagitating and obtaining intimate contact between F tion, the shaft [0 and the armature II are enthe reactants and the catalyst, said impeller beclosed in a pressure-t g t hOHSiP-g which ing mounted on a rotatable shaft connected with prises the cylindrical member l3 of suitable nonthe armature of an induction motor. The armamagnetic metal or alloy such as the chromiumture is separated from the field of the motor b a nickel-steel alloy known as stainless steel, dis-, sheath or pressure-tight housing of suitable nonposed about the rotor and the tubular or sleevemagnetic metal, alloy or the like, capable of with- 55 like member l4 dispo about Shaft l0. Memstanding the pressure employed in the reaction zone and communicating with the latter through a pressure-tight sheath or housing provided about the shaft. This eliminates the necessity for pack- .ing about the rotating shaft and, in the preferred The feature and advantages of the invention will be more readily apparent from an inspection of the accompanying diagrammatic drawing and the following description thereof.

The drawing is an elevational view shown prim cipally in section of one specific form of appa ratus embodying the features of the invention.

Referring to the drawing, reference numeral i designates the shell of a suitable reaction or mixing vessel which is provided with a closed bottom 2 having a suitable outlet and drain connection 3 and having a removable upper head or closure member l bolted to the shell, as indicated at 5, with a ground joint 8, or other suitable means of retaining pressure within the reaction and mixing zone, between the removable closure member and the shell. A suitable inlet connection 40 is provided onhead 4, for admitting fluid to the mixing vessel as will be later described.

An impeller or other stirring or mixing device of any desired form, indicated at 7, is provided within the mixing zone and, in this particular instance, the impeller is circumscribed by a series her II is secured at its lower end by welding or in any other convenient manner to a threaded connector II which is threaded to connection It provided on head 4, a suitable gasket it being provided between the abutting surfaces oi meming the mixing or reaction vessel from themotivating means for the impeller.

The upper end. oi member [4 is secured by welding or in any other convenient manner to a suitable closure member is at the bottom of the armature casing, member is being integral with member E3 or suitably secured thereto by welding or in any other convenient manner.

A suitable threaded collar 20 or the like is se cured to the upper end of, member ll, although these two members may be formed integral or otherwisesuitably attached, when desired, and a top closure plate 25 fits within member 20 and is detachably held in place against a suitable gasket 22, provided between member 20 and the upper end of member H, by cap screws 23 extending through a bolt plate 24 which is detachably threaded to collar 20. A case-hardened ring 25 is provided, in the case illustrated, between the cap screws 23 and the closure member 2|.

Shaft ill is supported at its upper end above the armature by a self-alignment bearing, indicated at 26, disposed in a suitable bearing housing 21 which is threaded, in the case illustrated, or may be attached in any other suitable manner to the closure plate 2|. The bearing is madeaccessible for lubrication through a threaded port 28 provided in closure plate 2| and connected. as shown at 28, to a suitable pressure-tight lubrication fitting, such as indicated, ior example, at l 'l, which projects through an opening provided in member 24.,

The motor is provided with an outer case 30 and suitable field coils, indicated diagrammaticalis at SI and connected by well known means, not illustrated, with a suitable source oi electric power, are disposed within-the space deflned between the outer case 30 and the armature housing.

' Suitable electrical insulation, such as the mica sheets, indicated at 32, are provided between the field coils and the inner and outer housings except that the cores )8 oi the field coils bear against member l3.

A suitable supporting structure oi any convenient form, such as indicatedior example at 33, is provided for the entire assembly.

As a special feature of the invention, a tubular Jacket 34, or the like, secured at its upper end to member I! and at its lower end to member i5 is provided about member I, with a space therebetween through which suitable cooling fluid may be circulated, ports I and 81 being provided through the wall 0! jacket M for the admission of the cooling fluid to space I! and ior its discharge thereirom. By virtue oi thisprovision, the substantial flow of heat through shaft II and member ll between the motor and the mixing or reaction zone is prevented.

It is. of also within the scope of the invention to provide a suitable jacket through which convective fluid may be circulated about the reaction or mixing vessel to control the temwithin the reaction or mixing lone,

though this well known provision is not illustrated in the drawing.

A motor oi the type herein provided and illustrated will develop considerable heat due to diltortion oi the magnetic ileld or impedance oiiered to the flow oi magnetic force between the field coils and the armature by member l3. In view oi this the invention provides ior dissipating a large portion of this heat, when required, to keep the operating temperature oi the motor within the required limits. This is accomplished, in the case illustrated, by means of a cooling coil, indicated at 38, through which cooling fluid may be circulated. The coil 38 is disposed adjacent the field coils within the space between the outer shell 30 of the motor and the armature housing, although it may, when desired, be replaced or augmented by a cooling coil wound about the outer case 30 or by providing a hollow outer case through which cooling fluid may be circulated.

In operation of the device fluids to be mixed may be continuously or intermittently supplied to vessel I through conduit and the resulting mixture may be continuously or intermittently removed from the vessel through conduit 3. This arrangement, may, of course, be reversed when desired, the incoming fluid being admitted through conduit 3 and the outgoing fluid discharged through conduit Alternatively, and

in accordance with the preferred mode of operating the device, one or more of the fluids to be mixed may be supplied through conduit 40 into the annular space provided about shaft l0 above bearing II. The fluid thus supplied in the apparatus is introduced under suiiicient pressure to force the same between the bearing I! and shaft 10 into the mixing zone. When desired, the shait 10 may be rifled adjacent bearing I2 as indicated at ll, to assist the flow a: fluid into the mixing zone, or a suiilciently loose fit may be provided between the bearing and the shaft to permit passage of the desired quantity oi fluid therebetween irom conduit 40' into the mixing zone;

The provision for introducing incoming fluid into the mixing zone between the bearing l2 and the shait, as above described, permits protection oi the bearing irom contact with excessively hot or corrosive ingredients oi the mixture by introducing a non-corrosive or relatively cool component oi the fluids to be mixed through conduit 40*, while introducing relatively hot and/or corrosive components thereoi through conduit 3 or conduit 40. For example, when the apparatus is employed in the catalytic alkylation 0! isobutane with butylenes employing a corrosive alkylating agent or catalyst such as phosphoric or sulfuric acid, a portion or all of the butylenee or a portion or all oi the isobutane to be reacted may be introduced in relatively cool state through conduit 40 while the remaining reactants and all or the corrosive catalyst is introduced through conduit 3 or conduit ll.

I claim as my invention:

1. An apparatus oi the 'class described comprising a closed pressure tight mixing vessel. an impeller disposed within said vessel. an electric motor above and spaced irom said vessel, a pressure tight casing around the rotor oi said motor and having a bottom closure member and a top closure member, a vertical ehait extending from the impeller through an opening in the top of said vessel and through an opening in said bottom closure member and connected with said rotor,abearingiortheshaitwithinsaidveseel adjacent the first-mentioned opening, and a tubular member depending from said bottom closure member and surrounding and spaced from the portion of said shaft outside said vessel, the annular space between said tubular member and shaft being in communication with the interior of said casing through the opening in said bottom closure member, said casing and tubular member forming a closed pressure tight chamber housing the rotor and said portion of the shaft and communicating with the interior of the vessel through said opening in the top of the vessel, the field coils of the motor being disposed outside said pressure tight chamber.

2. An apparatus of the class described comprising a closed pressure tight mixing vessel, an impeller disposed within said vessel, an electric motor above and spaced from said vessel, a pressure tight casing around the rotor of said motor and having a bottom closure member and a top closure structure, a thrust bearing enclosed within said top closure structure, a vertical shaft ex-- tending from the impeller through an opening in the top of said vessel and through an opening through the opening in said bottom closure member, said casing and tubularmember forming a closed pressure tight chamber housing the rotor and said portion of the shaft and communicating with the interior of the vessel through said opening in the top of the vessel, the field coils of .the motor being disposed outside said pressure tight chamber. I

GEORGE L. HERVERT.

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