US2239152A - Mixing machine - Google Patents

Description

April 22, 1941.

o. JAcoBsEN MIXING MACHINE Filed Aug. 12,1940

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' MIXING MACHINE Filed Aug. 12, vv1940 s' sheets-sheet s Inv emo R Owsmu .mamen BYAMTSM Patented Apr. 22, 1941 UNITED STATES PATENT GFFiCE MIXING MACHINE Oystein Jacobsen, Montgomery County, Ohio, as-

signor to The Durron Company, Inc., Dayton, Ollio, a corporation of New York Application August 12, 1940, Serial No. 352,238

6 Claims.

which the degree or amount of mixing or agitatingiscontrolled entirely apart and independently ofthe. speed of rotation of the mixer. Consequently, a prime mover of constant speed may be employed.

.The final object is to provide a mixer or stirrer in which the fluids or materials to be mixed are drawn under pressure into the mixture, and the mixture leaves the machine with considerable pressure or velocity.

The invention will be better understood when the following specification is perused in connection with the accompanying drawings.

In the drawings:

Figure 1 is a longitudinal sectional View, partly in elevation, of the improved mixing andl stirring machine.

Figure 2 is an enlarged fragmentary sectional view of 'the machine, but showing more particularly the details of the impeller and the mechanism by Which the, amount o-f fluid recirculation andv mixing are controlled.

Figure k3- is a perspective view of the impeller, looking at the vertical edge and with a portion cut away to expose the interior.

' Figure 4 is a central cross section, partly in elevation, O f the machine taken along the line 4..-,4 ig Figure 1 General arrangement In general, the improved machine of this invention is 'designed to mix lluids, such as sulphuric acid and water, or nitric acid and Water, also fluid-like materials, as for example, when it is desired to mix wateig'bleaching or chemical agents with pulpV during the manufacture of news printer chemical liquors with particles of solid material andv to draw these uids or solid materials by strong suction effect into the mixer, wherein they are thoroughly mixed, Vand iinally to expel the mixed fluids or materials at a high velocity or high pressure, or both. Hitherto, difculty'has been experienced in the design and construction of mixingY machines which operate by rotation `and which handle corrosive fluids as.

one or more of the mixture ingredients, and even more difficulty is present when large quantities of such material or fluids must be handled as a continuous process, and the degree of mixing must be readily controllable from a po-sition exterior of the mixing machine.

Ingeneral,A my invention contemplates a mixing machine which is constituted of three essential parts, namely, an impeller having two portions, one of which serves to produce a considerable suction eiect on'the mixture ingredients and the other of which serves to recirculate the ingredients within the machine, thereby assuring a'thorough mixing effect; the casing which is so designed as to permit the mixture ingredients to be readily admitted and also to allow these ingredients tobe recirculated from the casing, Vthrough the impeller andback to the casing in recirculatory paths; and iinally a mechanical adjustment means by which the axial position of the impeller Within the casing is changed to control the amount of the mixture which is caused to be recirculated. Y In order to successfully withstand the corrosive effects of any acids that may beemployed as one or more of the mixture ingredients, those parts of the machine with which the mixture comes into Contact are made of acid-resisting material, such as high silicon iron or alloy steel.

Construction Referring to the drawings in detail, the casing which houses the impeller is designated generallxr by the reference character l. This casing is constituted of a side plate 2 fabricated as a heavy casting of acid resistant iron'in case acids `are being handled, and is formed with a peripheral iiange which takes the shape of a volute, as shown in Figure 4. This iiange is designated by the numeral 3. The space within thellanged portion of the casing is drawn down to a neck, shown at 4, whichterm'inates Vin'an enlarged portion 5. 'Ihe opening in the neck portion'is preferably circular. There is a clamping ring 6 which bears against the under side of they nlarged portion 5, the purpose oi which is Vto permit connection With asimilar ring attached toy an outgoing' conduit (not shownlg" The central portion of the'side plate 2 is provided vwith an y outwardly extendinghub `l, provided with an internal bore which terminates at its right-hand end (Figure 1) in an inwardly'projecting shoulders;

The opposite side plate 9 of the casing is also constituted' as a' heavy casting of acid resistant iron when acids are being handled. The casting is provided at its outer periphery with an annular shoulder portion leaving a bearing surface which abuts a corresponding surface on the flanged portion 3 of the casing. The side plate 9 is provided with a relatively large hub-like extension l2, cored out to leave an inlet passageway or chamber i3. The inlet passageway or chamber |3 has a bore I4 machined to size, the purpose of which will be explained presently. A two-way coupling I5 is secured at the plate i@ to the extension l2, this coupling being connected through a shut-oi Valve I1 to a pipe i8 at one side, and to a pipe I9 through a Valve 23 at the other side. l

The two side plates 2 and 9 of the casing may be secured together in 'any suitable manner. However, inasmuch as these castings may be made of silicon iron which is not readily machinable, the two casing parts are closed, preferably by means `of a clamping structure. This structure is formed of two rings 2|, 22, disposed on opposite sides of the casing, which have openings to receive bolts 23, the shape of the rings 4and the position of these openings being such that the bolts 23 will clear the casing. The bolts are provided with nuts 24 which upon being tightened will serve toclamp the two sides `of the casing 2, 9 together, preferably rendering the joint indicated at completely fluid-tight. The volute-Shaped portion of the casing is provided at the bottom with a drainage aperture 25, closed by a cover plate 26 and secured to lthe casing extension 21 by means of the U-bolt 28.

The impeller is designated gen-erally by the reierence character 29, and consists of a central hub 30, disc-like side walls 3| and 32 and spirally directed impeller vanes 33 (Figure 4). The hub 30 is provided with outwardly curved surfaces 34, 35 forming respectively main and auxiliary inlet passages 36 and 31, with curved inner surfaces 33, 39 of the impeller discs 3| and 32. The curved surfaces 38 and 39 are additionally rounded at their ventrance portions 40 and 4| so :as to increase the efciency of inward iiow by taking care of the vena contracta effect. The hub 3) at its periphery 42 thus forms a partition separating the intake passageways 36 and 31, ,and likewise serving as a support for the remainder of the impeller by being joined as at 43 to the vanes 33.

The hub 30 of the impeller is ycarried on a shoulder portion 44 of 1a shaft 45, and secured thereto in any suitable and Well known manner. A sleeve 46 surrounds the shaft 45, this sleeve having a diameter as Irotatably to iit within the annular shoulder 8 of the casing. There are discs 41 of packing material contained within the cored-out hub 1, these discs being held in place .by a gland 48 secured to the hub 1 by means of bolts 49. The shaft 45 is carried by an end bearing 50 and an intermediate bearing 5|, of which only one has been shown in detail.

The bearing 5| is preferably of a ball bearing type, and is supported 4on a web 52 which extends radially outwardly to meet a frame 53 which extends to the left from the side plate 2 of the casing, to which -t may be secured in any suitable manner. As illustrated, the ring 22 is integral with an annular portion 54 of the frame so that by tightening the nuts 24 the frame is rigidly secured to the `casing as well as clamping the two halves of the casing together. The lower part of the frame 531s carried on a base 55, provided with bosses 56 for bolting to the oor. The lefthand end of the frame 53, as seen in Figure i, carries the end bearing 50, which is also so constructed as to provide an axial movement of the shaft 45 and `of the impeller connected to the shaft.

For maintaining the bearing in position the frame 53 is provided with an inwardly extending iianged portion 51 having a circular groove for receiving a circular ball race, indicated at 58, with ball bearings 59. The inner side of the ball race 58 is held against a shoulder provided on the ii-ange 51 by a retaining plate El), which is bolted as indicated at Y5| to the frame. The plate 60 is provided with arelatively large bore, grooved as indicated at 62, and is adapted to receive a sleeve 63. This sleeve terminates at one end in a hand wheel 64 and at `the other end is provided with a shoulder against which the lower ball race S5 fits, the latter being held in posi-tion by a ring BS which is screwed on a threaded end portion of the sleeve 63. The hand wheel 64 has a bore provided with threads which i'lt into corresponding threads of a threaded portion 61 of the shaft 45. The latter is extended beyond the threaded portion to receive a coupling 58, keyed thereto as indicated at 69. This coupling is for the purpose of making mechanical connection between the shaft 45 and an external source of mechanical power, such as an electric motor (not shown). There is a web 1|) joining the flanged por-tion 51 andthe lbearing 5i, the purpose of which together with the flange 52, is to form an oil-tight compartment between the bearings. Oil may be introduced into the compartment through an opening in the yboss 1|, and the height of the oil may be visually determined at the sight 12. The oil is kept at such a level in the compartment `as to nd access to both bearings 5i and 50.

From the foregoing it is evident that when a rotary effort is applied Ato the coupling 68, the shaft 45 will rotate and carry with it the hand wheel 54 and sleeve 63, together with the lower ball race 65. Consequently, there is no relative motion between the threads on the hand wheel and the threads 61 on the shaft. However, assuming that the shaft 45 is stationary, it is apparent that rotation of the hand wheel 54 will cause the sleeve 63 to be rotated, carrying with it the lower ball race 65 but without any relative longitudinal movement with respect to the frame 53. It will be noted that the'groove 62 Ain the plate 60 Yserves to reduce friction at this point to a minimum when the sleeve 63 is turned.' However, turning the hand wheel 64 relative tothe stationary shaft causes the latter to mo've right or left due to the threaded portion 61,and depending on the direction in which the hand wheel is turned. Thus the axial position of the impeller within the casing can be directly controlled by the movement ofthe hand wheel 54.' In order to lock the hand `wheel rin any desired'position with respect to the shaft,.a locking bolt 13 is provided which carries a shoe 14 providedwith threads bearing against the threaded portionof the shaft. It will be understood that when the bolt 13 is tightened the shoe 14 will prevent any longitudinal movement of the sleeve 63` with respect to the shaft, and thus prevent'rotation wheel 64, While Figure 2 shows the impeller at its extreme right-hand position, the hand wheel' in the mean time having been rotated to cause the impeller to move from left to right within casing. f It will. be understood that the casing ciV the ymachine is considerably wider than the width oftheimpeller so as to permit a substantial movement of the latter in an axial direction. Theside wall Si of the impeller is provided with a dat surface 'iii which bears against a corresponding surfacevlt of the casing when the impeller is atvitsy extreme left-hand position. The side wall S2 ofthe impeller terminates at the center in a relatively long neck portion 'Vl which iitsrsnugly within the bore Ill of the side plate 9 of the casing, and is providedwith a shoulder 'i8 which bears against a corresponding shoulder 7:9 of the casing when the impeller has been moved to its extreme right-.hand position.

Operation Let us assume that it is desired thoroughly to mix sulphuric acid and water in the improved machine. The wateris first admitted through the pipe i8 with the valve Il open, and the acid is admitted through the pipe i9 and the valve 2li to the YT-shaped coupling l5. The two liquids pass through the inlet'passageway E3 and enter the neck portion ll of the impeller. Assuming that the impeller is being rotated counterclockwise, as seen in Figure 4, the varies 33 will introduce a strong suction onv the two entering liquids, causing these liquids to move from the center of the impeller through the vane passageways and to leave the impeller at the periphery thereof. A certain amount of agitation ormixing of the two liquids takes place within the impeller under these circumstances, but for certain types of usage the mixing effect obtained in this manner is not sufficient. This would be particularly true in case a liquid, such as an acid, were introduced through one of the incoming pipes and a semi-solid material, such as pulp or a granulated material such as carbon dust, were introduced through the opposite pipe.

Whereas in the prior-art forms of pumps, in order to increase the rate of mixing it was necessary to change the speed of the impeller, in acu cordance with my improved machine the mix" ing rate can be either increased or decreased depending on Vthe requirements, without the slightest change in the speed of the impeller. This improvement is brought about by the use of a recirculatory path for vthe mixture contained within the machine, and effected by a longitudinal movement of the impeller.

Referring now to Figure 2 in which the impeller has been moved to its extreme right-hand position by the hand wheel 6ft, it will be noted that the combined iluids iirst pass through the annular passageway 33 land then through the vane compartments, but upon leaving the periphery of the impeller a large portion if not all of the combined fluid is caused to pass downwardly between the surfaces l5, it, due to the suction effect introduced by the vane portions to the left of the inner hub surface. This fluid is drawn through the passageway 3l and again introduced to the vane compartments, where it combines with the other fluid which has flowed n direct mixing eiiect introduced by a portion of the varies, and a recirculatory mixing eiect introduced by other portions oi the varies, all of thesey effects being vcommulative within the impeller. As great or as little of the fluid may be subjected to the recirculatory effect depending on the space left between the surface 15 of the impeller and the surface 'I6 of the casing, which in turn depends on the adjustment of the hand wheel dit.

In its preferred mode of operation the pump is rotated continually to mix two or more liquids, acids, etc. which have passed through the pipes ddii) by opening the valves l1, 2d. 'The rate of mixing depends not only on the speed with which the impeller is rotated but also on the position of the impeller with respect to the casing. In case the impeller is moved a predetermined distance to the right (Figure 1) the fluid leaving the periphery of the yimpeller will be drawn downwardly to the left of the impeller, as indicated in Figure 2, and will be caused to enter the impeller again through its left-hand inlet. This recirculation of the fluid causes the ingredients of the mixture to be thoroughly intermixed so that when the fluid is iinally ejected at vthe outlet passageway 8d, the elements of the mixture have been thoroughly incorporated with one another. It is apparent that a mixer of this character can handle large quantities of fluids in that the rate with which the mixed iluid leaves the machine is equal to the rate with which the iluids to be mixed enter the machine.

If desired the improved machine may be employed for intermittent operation in which independent charges areadmitted successively to the machine through the pipes it, i9. Assuming that the nrst charge has been admitted to the machine and that the valve in the outgoing pipe has been closed except for avent opening, the impeller is rotated at a predetermined speed and so adjusted with respect to the casing as to provide the proper amount of recirculatory eiect. Upon conclusion of the mixing operation the mixed fluid may be drained from the casing through the opening 25 after the cover plate 26 has been removed. The pump may then be primed in any suitable and well known manner, ready to receive the next charge of fluid to be mixed. The operation ci the machine is exactly the same when semi-solids are being mixed instead of rluids. The machine may be operated either continually or intermittently, as explained above. In the case of mashing and bleaching pulp by the use of acids, it is apparent that by operating the hand wheel S13 the mixing rate can be so adjusted as to exercise a careful control over the rate and the amount of mashing and bleaching that is given to the pulp. Many other desirable effects may be obtained by regulating the size of the recirculatory path between the impeller and the casing, and depending on the character of the materials that are introduced into the mixing machine. While it is preferred that the machine be stopped when the axial position of the impeller 1s being regulated at the hand wheel 64, it may on occasion be entirely practical to provide mechanism known to those skilled in the art, by which the shaft t5 may be moved in an axial direction during operation of the impeller, thus eliminating the necessity for shutting the machine down for adjustment.

It has been pointed out that the improved machine is adapted to mix two or more fluids, or one fiu1d and a semi-solid or granular material, so

that the terms fluid or uid-like materials set forth in the claims are intended to be suiciently broad to read on a huid, a semi-solid or a semi-fluid material.

It will be understood that I desire to comprehend within my invention such modifications as come within the scope of the claims and the invention.

Having thus fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

l. A rotary mixing machine for fluids comprising a casing containing a rotary impeller, said impeller having a hub dividing the central portion thereof into oppositely directed intake passageways which lead to an outward passageway, means for presenting all of the fluids into one of said passageways to be mixed by the impeller, and means for presenting at least a part of the mixed iiuid through a recirculatory path Within the casing to the other of said passageways whereby the fluids are recirculated through the impeller and are in a thoroughly mixed condition when leaving the machine.

2. A rotary mixing machine for fluids comprising a casing containing a rotary impeller, said impeller having a hub dividing the central portion thereof into oppositely directed intake passageways which lead to an outward passageway, means for presenting all of the fluids into one of said passageways to be mixed b-y the impeller, means for presenting at least a part of the mixed fluid through a recirculatory path within the casing to the other of said passageways whereby the fluids are recirculated through the impeller and are in a thoroughly mixed condition when leaving the machine, said casing being of greater width than the impeller, and means for shifting the impeller along its axis with respect to the casing whereby the amount of recirculated fluid is changed and the degree of mixing is controlled.

3. A rotary mixing machine, for fluids comprising a casing containing a rotary impeller, said impeller having a hub dividing the central portion thereof into oppositely directed intake passageways which lead to an outward passageway, means for presenting all of the uids into one of said passageways to be mixed by the impeller, means for presenting at least a part of the mixed fluid through a recirculatory path within the casing to the other of said passageways whereby the fluids are recirculated through the impeller and are in a thoroughly mixed condition when leaving the machine, a shaft secured to said hub, said casing being of greater width than the impeller, and means for moving said shaft axially to shift the impeller with respect to the casing whereby the amount of recirculated fluid is changed and the degree of mixing is controlled.

4. A rotary mixing machine comprising a casing containing a rotary impeller, said impeller including means for directing fluid-like materials outwardly from opposite sides of the impeller, means for presenting all of the materials to be mixed to one side of the impeller, and means for presenting the materials which have been given a preliminary mixing by the impeller through a recirculatory path within the casing to the other side of the impeller whereby the materials are recirculated through the impeller and are thoroughly in a mixed condition when leaving the machine.

5. A rotary mixer comprising a casing containing a rotary impeller, said impeller including a plurality of arcuate vanes and adapted to receive iiuids to be mixed into opposite sides of the impeller, said fluids leading the impeller at the outer tips of the vanes, said impeller being adapted to be shifted along its axis Within the casing to cause uid in different amounts to be received by the opposite sides of the impeller and to pass through a recirculatory path within the casing whereby the degree of mixing of the uids is determined by the position of the impeller with respect to the casing.

6. A rotary mixer comprising a casing containing a rotary impeller, said impeller including a pair of plates separated `by vanes the inner portions of which communicate with an inlet passageway and the outer pontions communicate with an outlet passageway, said impeller having a Width less than the width of the casing, means for adjustably positioning the impeller within the casing so as to leave a space between the impeller and the casin-g at the side opposite said inlet passageway, and means for presenting fluids to be mixed to the inlet passageway whereby as the impeller rotates the mixed iiuid leaving the impeller is caused to pass through said space between the impeller and' the casing and to recirculate through the vanes and entirely within the casing in order thoroughly to mix the iiuids within the impeller.

OYSTEIN JACOBSEN.

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