US3881702A

US3881702A - Blender

Info

Publication number: US3881702A
Application number: US406012A
Authority: US
Inventors: Donald James Mciver
Original assignee: Keystone International Holdings Corp
Current assignee: Keystone International Holdings Corp; Tyco Flow Control Inc
Priority date: 1972-04-07
Filing date: 1973-10-12
Publication date: 1975-05-06
Anticipated expiration: 1992-05-06

Abstract

A blender for powder and other solid particulate material including a container with multiple inlets at the bottom and openings for injecting a fluidized mixture of particulate material and air into the inlets, with upwardly diverging passageways extending upwardly from the inlets, and a method for blending solid particulate material utilizing such a blender.

Description

United States Patent [1 1 Mclver 1 BLENDER [75] Inventor: Donald James Mclver, Houston,

Tex.

[73] Assignee: Keystone International, Inc.,

Houston, Harris County, Tex.

[22] Filed: Oct. 12, 1973 [21] Appl. No.: 406,012

Related US. Application Data [63] Continuation of Ser. No. 242,010, April 7, 1972,

abandoned.

[52] US. Cl. 259/4; 34/57 A; 137/604; 141/18; 259/18; 259/DIG. I7 [51] Int. Cl BOlf 5/04 [58] Field of Search 259/4, 18, 36, 60, 95,

259/147, 151, DIG. 17; 222/459; 34/10, 57 A, 57 R; 302/27, 28, 60; 137/604; 141/18;

[56] References Cited UNITED STATES PATENTS 3,088,306 5/1963 Richter 68/181 mvi - A l l l [4 1 May 6, 1975 3,148,865 9/1964 McClellan 259/4 3,189,460 6/1965 Smith, Jr 3,334,868 8/1967 Lage 259/4 FOREIGN PATENTS OR APPLICATIONS 987,954 3/1965 United Kingdom 259/4 17,241 9/1955 Germany 259/4 Primary Examiner-Harvey C. Hornsby Assistant ExaminerAlan Cantor [57] ABSTRACT A blender for powder and other solid particulate material including a container with multiple inlets at the bottom and openings for injecting a fluidized mixture of particulate material and air into the inlets, with upwardly diverging passageways extending upwardly from the inlets, and a method for blending solid particulate material utilizing such a blender.

11 Claims, 7 Drawing Figures BLENDER This is a continuation of application Ser. No. 242,010 filed Apr. 7, 1972, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to apparatus and methods for blending dry particulate materials such as powders.

2. Description of the Prior Art Many dry granular, pelletized and pulverulent mate- I rials (all of which are included herein in the term particulate materials") are made in batches. Because of process variations it is seldom possible to make each batch identical in properties. Thus in order to obtain uniformity of product it is necessary to blend together a number of batches. Such blending, if done properly, results in a homogeneous mixture of materials from two or more different batches so that much more uniform product can be obtained.

Another application for blending is in the mixing of two or more completely different materials, such as the various dry products utilized in bakeries in making bread and other bakery products. For highest quality product a homogeneous mixture is highly desirable.

Because of such requirements many types of equipment have been developed for accomplishing blending. Various mechanical type mixtures predominate for blending of powdered materials. However, where granular or pelletized materials must be blended, development has concentrated on various pneumatic type blenders in which the material may, for example, be agitated by a high pressure fluid current, or be withdrawn from diverse locations of a container. In the latter type of device the blending container is first filled with the differing materials and the material is removed through conduits having openings vertically spaced apart so as to remove material from a plurality of levels at the same time. The material from the various conduits is fed into a single line. Examples of such apparatus are shown in, for example, the U.S. Pat. to Arthur et al U.S. Pat. No. 3,106,385, Bennett et al No. 3,138,369, Seifarth US. Pat. No. 3,158,362, Goins No. 3,216,629 and Schmidt-Holthausen No. 3,373,973. German Pat. No. 1,034,464 shows a variation of this type of equipment.

Such blending devices require a relatively complex and expensive structure, because of the number of conduits and openings required to insure efficient blending. Another disadvantage of such apparatus is that the blender must first be filled with the material to be blended, and then the blending operation performed. Sometimes it is necessary to recycle the material through the blender several times in order to obtain a suitable blend. Such delay greatly increases the expense of operation, as well as delaying other operations.

Another type of blender which has been utilized uses high pressure blasts or jets of air or a vacuum to aspirate material into and through lift tubes to cause material to move from a lower level in the blender container to an upper level and there be scattered in the blender. One such design is shown in the U.S. Fat. to Schneider No. 3,198,492, using an air jet, and another such design is shown in the patent to Solt et a1 U.S. Pat. No. 3,276,753, using a vacuum. Such designs also utilize the expensive tubular construction, and in addition require blending to be performed after the blender is filled with material, thereby causing time delays.

Although these pneumatic blenders have had drawbacks because of the problems mentioned, many of them have performed satisfactorily for the blending of granular and pelletized materials. However, powdered materials tend to pack down in the container, so that they do not flow readily, and therefore considerable difficulty has been encountered in blending such materials in pneumatic blenders heretofore known.

SUMMARY OF THE INVENTION According to the present invention highly efficient blending of powders and other particulate material is obtained during the filling of the blender with the material by injecting fluidized material into the bottom of the blender in such a manner as to cause injected material to flow upwardly through material already in the blender, causing agitation and trubulence of the material so as to obtain complete blending. Preferably the material is injected at a plurality of points, preferably at the bottom of the container, and the material is alternately injected into various of the injection points. In a preferred embodiment of the apparatus of this invention means are provided to cause the injected material to flow upwardly in a diverging path so as to obtain impingement of newly injected material throughout the cross-sectional area of the blender.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an elevational view of a preferred embodiment of the apparatus of this invention;

FIG. 2 is a horizontal sectional view of a portion of the apparatus of FIG. 1, taken at line 22 of FIG. 1;

FIG. 3 is an isometric view of a preferred embodimentof a portion for a blender according to this invention;

FIG. 4 is a schematic diagram of a control device suitable for operating the apparatus of this invention;

FIG. 5 is a chart illustrating one sequence of operation for valves in the embodiment shown in FIG. 1;

FIG. 6 is an elevational view of another embodiment of apparatus in accordance with this invention; and

FIG. 7 is a horizontal sectional view of the embodiment shown in FIG. 6, taken at line 77 of FIG. 6.

DESCRIPTION OF THE PREFERRE EMBODIMENTS In the embodiment of the invention shown in FIG. I a storage bin 10 is utilized for receiving batches of material to be blended, the material being received into the bin through the top opening 12. The bin 10 is provided with a hopper bottom 13 and a rotary valve 14, as is well known in the art, for removal of material therefrom. An air supply line 16 is connected to the inlet of the rotary valve 14, and line 18 is connected to its outlet. In many, if not most, installations the storage bin 10 is omitted, and material is fed to line 18 direct from production of the material. Line 18 leads to a three-way valve 20, which is also connected to a product line 19 and a line 21 leading to a manifold comprising a circular conduit 22 having a plurality of outlet conduits 24 leading therefrom. A quick opening valve such as a butterfly valve 26 is provided in each of the conduits 24. In the embodiment shown a pneumatic valve operator 28 is provided for each valve 26.

The conduits 24 lead radially into the circumferential wall of a vertical right cylindrical container 30 which comprises the housing in this embodiment of the blender of this invention. Where a larger diameter container is used, the conduits 24 may extend radially outwardly from a center connection, and may connect into the bottom of the container, or may enter the container at an angle. An air inlet line 27 having an adjustable valve therein leads into each conduit 24 adjacent its connection to the container 30.

Container 30 comprises a pressure tight housing with a hopper bottom. The particular hopper bottom disclosed in FIGS. 1, 2 and 3 is of unique configuration. Thus, as best seen in FIG. 3, the bottom comprises a central cone 32 having a base diameter substantially identical to the inside diameter of the container 30, so that the base of the cone is substantially at the bottom of the container. A plurality of downwardly diverging radial wedges 34 terminate at their upper extremities in ridges 35 which, in the preferred embodiment, are located substantially lower than the apex of the cone 32. The downwardly diverging sides 37 of adjacent wedges 34 form, with the wall of the cone and the surrounding wall of the container, a plurality of upwardly diverging fluid passageways spaced circumferentially around the bottom of the container, with the upper end of each passageway intersecting the upper ends of adjacent passageways. The lower end of each of such upwardly diverging fluid passageways coincides with a connection to one of the conduits 24.

The slope of the cone 32 and of the sides of the wedges 34 may vary depending upon the angle of repose of the particular material which is to be blended. However, it has been found that an angle of about 60 to the horizontal is relatively easily accomplished, and such an angle exceeds the angle of repose of most ma terials which are handled in the blenders, so preferably an angle of at least 60 is used.

In the embodiment shown in the drawing the container 30 is provided with a man-way 36 in the top to allow entry for cleaning or inspection or the like. In order that operators may view the blending operation an inspection port 38, covered by a transparent material, and a light 40 may be provided.

A vent 42 in the upper end leads to a dust collector, such as, for example, a bag-type dust collector of a type well known in the art. A recycling line 44, for a purpose which will hereinafter be explained, is also preferably provided at an upper end of the container.

It will be apparent that in the operation of the apparatus a plurality of batches of dry, particulate material are received from a production source or are stored in the bin 10. In the process of this invention, such material comprises a plurality of different materials, whether different batches of the same product or different products, in dry, particulate form. The apparatus is particularly beneficial in the blending of powdered materials, but granular materials, and even pellets, can also be blended by the apparatus and method of this invention. Thus the term dry, particulate material is intended to include powdered, granular and pelletized materials.

When it is desired to blend the material, operation of the rotary valve 14 together with air flowing through the line 16 produces a fluidized mixture of the powdered material in the line 18. With the valve 20 in the position shown in FIG. 1, this material is fed into the manifold 22. In the preferred embodiment of the invention the fluidized material is not fed through all of the valves 26 at the same time, since the large flow area would greatly reduce the velocity. Instead some of the valves are closed while one or more of the others are open. The limiting factor is the flow volume available. With higher flow rates, more valves can be opened at the same time. I

It would, of course, be possible to open and close valves 26 by hand, but preferably automatic apparatus is provided for alternately opening and closing valves in a repetitive sequence so that the material flows through first one line 24 and then another. The material may be fed through the various conduits 24 in any desired order. One embodiment of apparatus for automatic operation of the valves 26 is depicted in FIG. 4.

In this apparatus a conventional timer motor 46 is provided with power from a power supply 48 by closing a switch 50. The timer motor may drive a' plurality of cams which are positioned to engage switches 51 to 56. The closing of each of these switches energizes one of a series of solenoid valves numbered 61 through 66. As is well known in the art, such solenoid valves provide air to or release air from the pneumatic cylinders 28 which act as operators for the valves 26.

In the preferred operation of the apparatus of this invention the cams driven by the timer motor 46 are designed so as to insure that all of the valves 26 will not be closed at the same time. This is accomplished by starting the opening of one valve before the preceding valve has fully closed. An example of one method of operation is illustrated in FIG. 5. As there shown, each of the six solenoid operated valves may be open for 6 seconds in a 30-second cycle. Thus solenoid 61 is energized at 0 seconds and de-energized at 6 seconds, solenoid 62 is energized at 5 seconds and de-energized at l 1 seconds, etc., so that there is a 1 second overlap at each stage of the cycle.

It will be appreciated that the various cams may be designed to operate the valves 26 in any desired order, although the simplest order is to position them so as to open and close the valves 26 in sequence around the blender.

As each valve 26 is opened fluidized material is fed into the bottom of one of the passageways formed between the cone 32, the wall of the container 30 and the sides of the wedges 34. In this embodiment it will be appreciated that the material flows into the passageway in a horizontal direction, and is deflected upwardly by impingement on the upwardly diverging surfaces. The fluidized material is thus caused to spread out as it moves upwardly through the diverging passageways. Such deflection and spreading of the material insures that incoming material mixes with material already in the blender, which results in highly efficient blending of materials therein. By continuously changing the inlet through which material is received, further intermixing of the material is achieved. It is to be appreciated that material flowing upward from each inlet on a diverging path may fall at almost any place within the container. Thus after the first batch of material from the bottom of the bin 10 is fed into the blender the second batch is blown upwardly through the first batch of material, with the velocity ofinjection causing intimate intermixing in and above each of the diverging passageways, and with the intermixed material caused by injection through each passageway falling over other passageways so to cause further intermixing of the material.

The amount of air pressure required for the operation of the blender will vary depending upon the particular material which is being blended and the height of the container 30. Air pressures as low as about pounds per inch and as high as about 100 pounds per square inch or more may be used effectively. Actual pressures required for adequate blending are usually not substantially greater than those required for conveying the fluidized material. In one installation where the blending container was 50 feet high it was found that a pressure of only 2 pounds per square inch greater than the normal conveying pressure was sufficient to blend all the way to the top of the container.

After the blender is filled the material may be removed therefrom by rotating the valve to connect the manifold with line 19, and applying a vacuum through the line 19 while operating the valves 26. Air for fluidizing the material to cause it to flow through the lines 24 and the line 19 may be provided by means well known in the art, as, for example, through valves 25 connected to each of the lines 24. If the valves 26 are operated in succession as during the filling, additional blending of the material is obtained during removal of the material from the blender. Because of the slope of the wedges 34 and the cone 32, and the unique bottom formed by them, there are no dead spots in the container, and all the material therein may be removed.

In some instances it will be found that insufficient blending has been obtained during the filling and emptying of the blender. In such an event the material may be recycled into the blender by withdrawing material by means of a vacuum and returning it through the line 44, as for example by means of vacuum-pressure conveying equipment such as is shown in US. Pat. No. 3,069,205. Further blending is obtained. during removal of the material from the blender the second time. Alternatively the material may be returned to the bin 10 for another complete cycle through the blender.

It is contemplated that in most installations the blender will be filled by pressure and emptied by vacuum, and any system known in the art suitable for that purpose may be used.

Another form of apparatus suitable for practicing the process of this invention is illustrated in FIGS. 6 and 7. In this embodiment the container 130 is rectilinear in cross-section, and the bottom is formed by a plurality of hoppers 132 of inverted pyramidal shape. A manifold 122 is connected to the threeway valve 20, and is also connected to conduits 124 leading to the bottom of the hoppers through the valves 26. As shown, the conduits 124 lead vertically into the apexes of the hoppers 132 rather than horizontally, as in the embodiment of FIGS. 1-3. The operation of the blender of this embodiment is. however, substantially the same.

The apparatus and method of this invention are particularly advantageous for blending powdered materials. Powdered material has been defined as that having 100% under 50 mesh, 90% under 100 mesh, 60% under 200 mesh, and substantially equal distribution thereafter. Such materials pack down when stored in a container, so that it is difficult to make them flow in pneumatic blenders heretofore used. However, this apparatus and method are also desirable for blending other particulate materials, since considerable time saving results from being able to blend while the material is flowing into the blender.

Another advantage is found in the blending of polyethylene pellets. These tend to smear and leave streamers attached to walls of tubes through which they are conveyed, as in the pneumatic blenders previously known. Friction of such particles on the tubes caused the tubes to heat up, which accentuated the problem. In the present apparatus, however, no such tubes are required, so such smearing is not encountered.

Although it has previously been known to fill containers by blowing a fluidized mixture of air and a particulate material into the bottom, this has been done only for the purpose of filling, and such filling operations were not conducted in such a way as to cause blending of two or more differing materials.

Various other structures for practicing the method of this invention will be apparent to those skilled in the art. In addition, those viewing the embodiments herein disclosed will be able to conceive of variations thereof within the scope of the invention. Accordingly, the invention is not limited to the specific embodiments shown and described, but only to those embodiments included within the scope of the appended claims.

I claim:

1. Apparatus for blending a plurality of diverse dry pulverulent materials, comprising a pressure tight container having a plurality of hoppers forming its bottom, and

means for injecting fluidized dry pulverulent material into the bottom of each hopper. said plurality of hoppers comprising a central cone having its base substantially at the bottom of the container and means including the cone and the surrounding wall of the container defining a plurality of upwardly diverging fluid passageways having one of said means for injecting material in communication with the lower end of each said passageway.

2. Apparatus as defined by claimed 1 wherein said passageways are spaced circumferentially around said cone and merge together below the upper end of said cone.

3. Apparatus for blending a plurality of diverse dry pulverulent materials, comprising a pressure tight container having a plurality of hoppers forming its bottom, and

means for injecting fluidized dry pulverulent material upwardly from the bottom of each hopper,

said means including means for injecting material into one hopper in the absence of injecting material into another hopper, and for injecting material into said other hopper in the absence of injecting material into said one hopper, and also including means for spreading the injected material laterally while it is moving upwardly so that the injected material from each hopper intersects material previously injected from another hopper during such upward movement, whereby material from each hopper is mixed with previously injected material from another hopper during such upward movement.

4. Apparatus as defined by claim 3 and including means for withdrawing the pulverulent material from the bottom of each hopper, and

means for combining the material withdrawn from the hoppers into a single fluidized stream.

5. A method for blending a plurality of diverse dry pulverulent materials in a pressure tight container having a plurality of hoppers forming its bottom, comprising injecting a first fluidized dry pulverulent material upwardly from the bottom of a first number of said hoppers in the absence of injecting material into a second number of hoppers,

injecting said first material into said second number of hoppers in the absence of injecting material into said first number of hoppers.

spreading out the first material while it is moving upwardly from said first number of hoppers in an upwardly diverging path which intersects the path of such material moving upwardly from said second number of hoppers, whereby the first material from the hoppers is intermixed while it is moving upwardly in the container,

injecting, after said first material, a second fluidized dry pulverulent material from outside the container into and upwardly from the bottom of said container from said hoppers, so that said second material passes up through at least a portion of the first material, and spreading out the second material, while it is moving upwardly from at least one hopper, in an upwardly diverging path which is intersects the path of second material moving upwardly from another hopper, whereby the second material from different hoppers is intermixed and also mixed with the first material, such mixing occurring both while the materials are moving upwardly in the container and while they are falling downwardly therein.

6. A method comprising air conveying a first fluidized dry pulverulent material,

injecting said first material substantially at the bottom of a container,

directing said first material upwardly toward the top of said container,

air conveying a second fluidized dry pulverulent material,

injecting said second material substantially at the bottom of said container at a plurality of points,

directing said second material upwardly toward the top of said container through substantially all of the first material, whereby the first and second materials are caused to be blended.

withdrawing the blended material from the bottom of said container at said plurality of points, and combining the withdrawn material. 7. A method as defined by claim 6 wherein the second material is alternately injected at said plurality of points in repetitive succession.

8. A method as defined by claim 7 wherein the injection at each point is begun just before termination of injection at the immediately preceding injection point.

9. A method comprising injecting a fluidized dry pulverulent material upwardly from the bottom of a container at a plurality of dispersed injection points, spreading out the fluidized material from at least one injection point in an upwardly diverging path which intersects the path of fluidized material from another injection point, whereby material from the two injection points is intermixed, and

removing said material from said container at said injection points.

10. A method for blending a plurality of dry pulveru lent materials in a bin which comprises injecting a mixture of a first material and a gaseous fluid upwardly into the bin, and then injecting a mixture of a second material and a gaseous fluid upwardly into the bin from a level below substantially all of the material in the bin at a velocity sufficient to cause injected material to flow upwardly through the material above the injection point, the second material being injected into the bin at a plurality of points below the surface of the material already in the bin, and

withdrawing material from the bin at said plurality of points and recombining the material.

11. A method comprising injecting a fluidized dry pulverulent material upwardly from the bottom of a container at a plurality of dispersed injection points, said material being injected substantially horizontally against a wall diverging upwardly and away from the point of injection, and

spreading out the fluidized material from at least one injection point in an upwardly diverging path which intersects the path of fluidized material from another injection point, whereby material from the two injection points is intermixed.

Claims

1. Apparatus for blending a plurality of diverse dry pulverulent materials, comprising a pressure tight container having a plurality of hoppers forming its bottom, and means for injecting fluidized dry pulverulent material into the bottom of each hopper, said plurality of hoppers comprising a central cone having its base substantially at the bottom of the container and means including the cone and the surrouNding will of the container defining a plurality of upwardly diverging fluid passageways having one of said means for injecting material in communication with the lower end of each said passageway.

3. Apparatus for blending a plurality of diverse dry pulverulent materials, comprising a pressure tight container having a plurality of hoppers forming its bottom, and means for injecting fluidized dry pulverulent material upwardly from the bottom of each hopper, said means including means for injecting material into one hopper in the absence of injecting material into another hopper, and for injecting material into said other hopper in the absence of injecting material into said one hopper, and also including means for spreading the injected material laterally while it is moving upwardly so that the injected material from each hopper intersects material previously injected from another hopper during such upward movement, whereby material from each hopper is mixed with previously injected material from another hopper during such upward movement.

4. Apparatus as defined by claim 3 and including means for withdrawing the pulverulent material from the bottom of each hopper, and means for combining the material withdrawn from the hoppers into a single fluidized stream.

5. A method for blending a plurality of diverse dry pulverulent materials in a pressure tight container having a plurality of hoppers forming its bottom, comprising injecting a first fluidized dry pulverulent material upwardly from the bottom of a first number of said hoppers in the absence of injecting material into a second number of hoppers, injecting said first material into said second number of hoppers in the absence of injecting material into said first number of hoppers. spreading out the first material while it is moving upwardly from said first number of hoppers in an upwardly diverging path which intersects the path of such material moving upwardly from said second number of hoppers, whereby the first material from the hoppers is intermixed while it is moving upwardly in the container, injecting, after said first material, a second fluidized dry pulverulent material from outside the container into and upwardly from the bottom of said container from said hoppers, so that said second material passes up through at least a portion of the first material, and spreading out the second material, while it is moving upwardly from at least one hopper, in an upwardly diverging path which is intersects the path of second material moving upwardly from another hopper, whereby the second material from different hoppers is intermixed and also mixed with the first material, such mixing occurring both while the materials are moving upwardly in the container and while they are falling downwardly therein.

6. A method comprising air conveying a first fluidized dry pulverulent material, injecting said first material substantially at the bottom of a container, directing said first material upwardly toward the top of said container, air conveying a second fluidized dry pulverulent material, injecting said second material substantially at the bottom of said container at a plurality of points, directing said second material upwardly toward the top of said container through substantially all of the first material, whereby the first and second materials are caused to be blended. withdrawing the blended material from the bottom of said container at said plurality of points, and combining the withdrawn material.

7. A method as defined by claim 6 wherein the second material is alternately injected at said plurality of points in repetitive succession.

9. A method comprising injecting a fluidized dry pulverulent material upwardly from the bottom of a container at a plurality of dispersed injection points, spreading out the fluidized material from at least one injection point in an upwardly diverging path which intersects the path of fluidized material from another injection point, whereby material from the two injection points is intermixed, and removing said material from said container at said injection points.

10. A method for blending a plurality of dry pulverulent materials in a bin which comprises injecting a mixture of a first material and a gaseous fluid upwardly into the bin, and then injecting a mixture of a second material and a gaseous fluid upwardly into the bin from a level below substantially all of the material in the bin at a velocity sufficient to cause injected material to flow upwardly through the material above the injection point, the second material being injected into the bin at a plurality of points below the surface of the material already in the bin, and withdrawing material from the bin at said plurality of points and recombining the material.

11. A method comprising injecting a fluidized dry pulverulent material upwardly from the bottom of a container at a plurality of dispersed injection points, said material being injected substantially horizontally against a wall diverging upwardly and away from the point of injection, and spreading out the fluidized material from at least one injection point in an upwardly diverging path which intersects the path of fluidized material from another injection point, whereby material from the two injection points is intermixed.