US 3181840 A
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Description (OCR text may contain errors)
C. A. RIETZ MIXING APPARATUS May 4, 1965 2 Sheets-Sheet 1 FilId April 12, 1962 INVENTOR. (ar/ 4. 5/? (z.
United States Patent 3,181,840 MIXING APPARATUS Carl A. Rietz, San Francisco, Calif., assignor to Rietz Manufacturing Co., Santa Rosa, Calif, a corporation of California Filed Apr. 12, 1962, Ser. No. 186,969 2 Claims. (Cl. 259--9) This invention relates generally to a mixing apparatus of the heat exchanger type capable of heating fluid materials continuously to a desired temperature level.
In many industrial processes it is necessary rapidly to heat materials which have physical characteristics such that they cannot be satisfactorily handled in conventional heat exchangers. Particular reference can be made to materials containing substantial amounts of solids that are suspended, dissolved and/or dispersed as a colloid in water or other liquid medium. In the food industry, such materials may be aqueous mixes, slurries, pulps or purees, in various concentrations. Particular reference can be made to materials containing ground or disintegrated meats, fatty materials and/or powdered or flaked solids. During the heating of such materials, it is generally desirable to avoid burning or objectionable impairment of heat sensitive components, whereby properties such as color, flavor, and nutrients present are detrimentally affected. Assuming that a rapid temperature increase is desired, the heating should be effectively distributed throughout the mass, without localized overheating. Conventional mixing devices of the heat exchange tube type, are not satisfactory for the rapid heating of relatively thick or viscous mixes or slurries, because for such operations they are subject to formation of incrustations, overheating or burning of heat sensitive components, and in general the heat is not properly distributed to the material undergoing treatment. Even as applied to the more fluid mixes or slurries, heat sensitive components tend to be impaired.
In general it is an object of the present invention to provide a mixing apparatus of the heat exchanger type suitable for the eflicient and rapid heating of various materials, including particularly mixes and slurries of the type referred to above.
Another object ofthe invention is to provide a mixing apparatus characterized by rapid and eflicient heat transfer without localized burning or overheating, and which can be employed to heat materials that are relatively thick or viscous.
Further objects of the invention will appear from the following description in which the preferred embodiment has been set forth in detail in conjunction with the accompanying drawing.
Referring to the drawing:
FIGURE 1 is a side elevational view partly in section illustrating apparatus incorporated in the present invention.
FIGURE 2 is an end view of the apparatus shown in FIGURE 1, looking toward the left-hand inlet end.
FIGURE 3 is a side elevational view illustrating the rotary shaft incorporated in the apparatus, together with parts carried by the shaft.
FIGURE 4 is a cross sectional view on an enlarged scale, taken along the line 44 of FIGURE 1.
The particular embodiment of my invention illustrated in the drawing consists of a cylindrical or tubular mixing apparatus 10, which generally is mounted for operation in a horizontal position. The walls of this member are made of metal or metal alloy having good heat conductivity, and which is compatible with the material to be processed. The member is provided with a surrounding heating jacket 11, which is adapted to receive steam or other suitable heating fluid. It is shown provided with a steam connection 12, a condensate outlet 13, and an air vent 14. Also it can be provided with a safety blow off valve connection 15.
Flanges 16 and 17 are shown attached to the ends of the jack 11, as by welding. Also the ends of the cylindrical chamber 10 are sealed with respect to the flanges 16 and 17.
The left hand end of the apparatus (FIGURE 1) into which the material is fed, consists of a cylindrical portion 18, which is an. extension of the cylindrical member 10. A conduit 19 communicates with portion 18, and in turn may be fed by a suitable hopper or like means. Preferable conduit connects tangentially with portion 18, as shown in FIGURE 2.
The right hand end of the apparatus (FIGURE 1) from which heated material is discharged is provided. with the discharge conduit 21, which connects through the adjacent end portions of member 10 and jacket 11. This conduit may likewise connect tangentially. The left hand end of member 10 is closed by cover plate 22, and the right hand end of jacket 11 is closed by plate 23,. which is sealed with respect to the adjacent end of member 19.
Extending axially within the tubular member 10 there is a rotor assembly including a hollow shaft 24 which can be formed by a tube of suitable metal, such as stainless steel. The ends of' the shaft 24 are provided with shaft extensions 25 and 26. Shaft extension 25 projects through the sealing gland 27, and is carried by the bearing assembly 28 and 29. Shaft extension 25 projects through the sealing gland 30 and is supported by the bearing assembly 31.
The construction of the rotor can be understood by reference to FIGURES 3 and 4. At the left hand or feed end, means are provided for acting upon the material and for advancing it through the space between the shaft and the walls of the tubular member 10. Thus a flight 32' is mounted upon the end .of the shaft, and is inclined whereby when the shaft is rotated, material is acted upon to urge it toward the discharge end.
Distributed along the length of the shaft, between the feed and discharge ends, are a plurality of scraping de-' vices which engage andscrape over the wall of the tubular member 19. Each scraping device consists of a pair of support arms 33 which are attached to the shaft 24 as by welding, and which are spaced along the length of the shaft. Extending between the free ends of the arms 33, there is a mounting bar 34 (FIGURE 4) which serves to carry the scraper blade 36; The'ends of the bar 34 are pivotally attached to the arms 33, as by means of end extension arms 37 and pivot pins 33.
The scraper blade 36 is attached to the mounting bar 3 by suitable means, such as the rivets (not shown).
The leading position 39 of the blade is beveled to an edge which in normal operation contacts and scrapes over the inner surface of the chamber 10. The blade can be made of suitable low friction material, such as a suitable plastic material like a reinforced laminated phenol resin (e.g. Formica). As shown in FIGURE 4 the scraper blade engages the inner surface of the tubular member 10 at anacute angle, and with clockwise rotation, it effectively separates material from the hot surfaces and directs it inwardly. The trailing portions 41 are similarly tapered, whereby the blades can be reversed to extend their useful life.
In the embodiment illustrated, the scraper devices are distributed in a plurality of longitudinally displaced regions. The first region is adjacent the feed end, and consists of two scraper devices disposed at diametrically opposite sides of the shaft 24. The second region likewise consists of two scraper devices disposed on diametri- 3,1s1,sao
cally opposite sides of the shaft 24, with the plane of the scrapers disposed 90 from the plane of the scrapers in the first region. A third region again has two scraper devices on diametrically opposite sides of the shaft 24, and the plane of these devices is substantially coincident with the plane of the scraper devices in the first region. In all six such regions are shown, with the understanding that the number may vary in different instances, depcn ing on requirements.
In addition to the scraper devices, the shaft 24 is provided with a plurality of paddle-like blades 42. As shown in FIGURE 3 these blades are distributed in the several regions mentioned above, and also in the region nearest the discharge outlet 21. The distribution is both circumferential and axial.
A suitable mounting means for the paddles is shown in FIGURES 3 and 4. On four sides the shaft 24 is formed with the flattened surfaces 4.3. Rods 44 extend diametrically through the shaft and are sealed where they pass through the walls of shaft 24, as by welding. Each paddle has a drilled hole near its central axis, whereby it can be positioned on a project threaded end 46 of a rod and clamped in place by nut 47. By loosening a nut 47, the corresponding paddle 42 can be adjusted to a desired position.
As shown on FIGURES 3 and 4 each region along the length of the shaft is occupied by two scraper devices disposed 180 apart. Each scraper is preceded by a paddle 42 inclined to urge the material toward the discharge end. Also each scraper is followcd by a paddle having its plane substantially parallel to the axis of the shaft, and serving to urge material outwardly.
At the feed end of the shaft 24 there is a rotor disk 49 which can be made of suitable material such as a plastic laminate. It is fixed to the shaft and has a diameter only slightly less than the inner diameter of member 10. The disk facilitates retraction of the rotor from member 10, because when the rotor is retracted toward the right, the weight of the left hand end is carried by the disk, thus supporting the member until it is completely withdrawn. Because it is made of a plastic laminate, the disk rides over the polished inner surface of member without injury.
Operation of the mixing apparatus is as follows: A feed material, such as a thick slurry containing meat and fat is fed at a continuous rate to the feed conduit 19, While the shaft extension is being driven at a suitable speed, such as from 25 to 1,000 rpm. As material enters the first region being swept by the scraper devices, it is recurrently and momentarily separated from the surfaces of the tubular member 10. In addition to being operated upon by the scraper devices, the material is engaged by the paddle-like blades 42. The blades that are set at an angle to the axis of the shaft urge the material toward the discharge end. The paddles 42 which are substantially parallel to the shaft subject the material to relatively intense agitation between the intervals that the material is acted upon by the scraper blades. A further function performed by the paddle-like blades is to urge the material outwardly against and spread it upon the inner heated surfaces of the member 10, immediately after the material is separated from said surfaces by the scraper blades. In the region of chamber 10 near the discharge conduit 21, one of the scraper devices can be omitted.
The action just described is repeated and continues as the material progresses through the apparatus. At the discharge end of the member 10 the material is at a temperature level approximating the temperature of the walls of chamber 10. It is discharged at the desired temperature level, through the conduit 21.
It will be evident that the apparatus described above is capable of eflicient and effective heating of various materials, such as slurries, pulps, purees, and the like, to a desired temperature level, Without serious injury to heat sensitive components. Adjustments can be made to suit varying operating conditions, including various materials being handled, various rates of feed, and the temperature level to which the material is to be delivered. Special feeding pumping means for delivering material to the apparatus under pressure is not required, because the apparatus by its construction, moves the material from the feed inlet to the discharge outlet. Although the apparatus is particularly capable of effectively heating thick mixes or slurries without burning or heat injury, it can be used on more fluid feeds, such as various pulps, purees and the like.
While the apparatus is intended to heat materials to a desired elevated temperature, it may be used for chilling materials, by supplying a refrigerant fluid to the jacket 11.
1. In apparatus of the character described, a tubular member for supplying feed material to one end portion of said member and for removing material from the other discharge end, a rotary shaft extending axially of the chamber, a plurality of scraper blades, means for mounting said scraper blades in regions distributed along the length of the shaft and spaced circumferentially, each scraper blade being adapted to engage and scrape over a portion of the inner surface of said member, and a plurality of paddle-like blades carried by the shaft in regions occupied by the scraper blades, said blades serving to act upon material being treated, certain of said paddle-like blades being inclined with respect to the axis of rotation of the shaft, thereby serving to urge the material toward the discharge end of the same, other ones of said paddle-like blades being disposed to urge the material outwardly against the inner periphery of said tubular member, each scraper blade having an inclined paddie-like blade preceding the same and one of said other blades following the same.
2. Apparatus as in claim 1 in which said inclined paddle-like blades are adjustably mounted on said shaft whereby the inclination of the same can be adjusted.
References Cited by the Examiner UNITED STATES PATENTS 1,767,376 6/30 Kramer 259- 2,526,367 10/50 Kaltenbach et a1 259133 2,589,350 3/52 Edmunds 2599 X 2,591,601 4/52 Peters et a1. 2599 X 3,020,025 2/ 62 OMara 2599 X 3,090,606 5/63 Burnet 259109 FOREIGN PATENTS 664,880 1/52 Great Britain. 1,007,684 5/57 Germany.
CHARLES A. WILLMUTH, Primary Examiner.