CA1170649A - Mixing apparatus - Google Patents
Mixing apparatusInfo
- Publication number
- CA1170649A CA1170649A CA000397271A CA397271A CA1170649A CA 1170649 A CA1170649 A CA 1170649A CA 000397271 A CA000397271 A CA 000397271A CA 397271 A CA397271 A CA 397271A CA 1170649 A CA1170649 A CA 1170649A
- Authority
- CA
- Canada
- Prior art keywords
- mixer
- particles
- compartment
- partition walls
- discharge port
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
- B65D88/00—Large containers
- B65D88/26—Hoppers, i.e. containers having funnel-shaped discharge sections
- B65D88/28—Construction or shape of discharge section
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/80—Falling particle mixers, e.g. with repeated agitation along a vertical axis
- B01F25/82—Falling particle mixers, e.g. with repeated agitation along a vertical axis uniting flows of material taken from different parts of a receptacle or from a set of different receptacles
- B01F25/822—Falling particle mixers, e.g. with repeated agitation along a vertical axis uniting flows of material taken from different parts of a receptacle or from a set of different receptacles the receptacle being divided into compartments for receiving or storing the different components
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/80—Falling particle mixers, e.g. with repeated agitation along a vertical axis
- B01F25/84—Falling-particle mixers comprising superimposed receptacles, the material flowing from one to the other, e.g. of the sandglass type
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/26—Mixers with an endless belt for transport of the material, e.g. in layers or with mixing means above or at the end of the belt
Abstract
ABSTRACT
Apparatus is provided for blending batches of particulate material that axe compositionally hetero-geneous into batches of material that are compositionally uniform. The apparatus consists of two or more cylin-drical static mixers, each mixer being substantially iden-tical in volumetric capacity and construction. Each mixer contains six or more vertically aligned partition walls that extend radially from the midpoint of the mixer to the wall to divide the mixer into at least six storage com-partments of substantially equal volumetric capacity. The vertical partition walls differ in height in a regular descending order so that as material is charged to and fills one compartment, it overflows the shorter wall to fill the adjacent compartment. One embodiment of the inven-tion includes means for feeding particulate material suc-cessively through each of the static mixers. A second embodiment of the invention includes means for simultan-eously discharging lots of particulate material from each of the mixers at a substantially uniform rate into a common conveying means.
Apparatus is provided for blending batches of particulate material that axe compositionally hetero-geneous into batches of material that are compositionally uniform. The apparatus consists of two or more cylin-drical static mixers, each mixer being substantially iden-tical in volumetric capacity and construction. Each mixer contains six or more vertically aligned partition walls that extend radially from the midpoint of the mixer to the wall to divide the mixer into at least six storage com-partments of substantially equal volumetric capacity. The vertical partition walls differ in height in a regular descending order so that as material is charged to and fills one compartment, it overflows the shorter wall to fill the adjacent compartment. One embodiment of the inven-tion includes means for feeding particulate material suc-cessively through each of the static mixers. A second embodiment of the invention includes means for simultan-eously discharging lots of particulate material from each of the mixers at a substantially uniform rate into a common conveying means.
Description
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In the manufacture of particulate materials such as thermoplastic polymers, e.g., high pressure polyethy-lene, it is observed that certain lots will have a desired property such as melt index which falls outside of product specifications. To provide a maximum percentage of product falling within product specifications, the manufacturer will blend a product lot having an undesirably high melt index with a product lot having an undesirably low melt index.
The resulting mixed lot will have a melt index within spe-cifications. Such lots customarily are mixed in rotary mixers and/or remelted and extruded. Such reprocessing entails high labor costs and, in addition, high energy costs when an extrusion step is employed.
In incorporating additives such as slip agents, antiblock agents, and the like into such resins, it is custo-mary to first prepare dry blends of the resin and addi-tive(s) and then extrude the dry blend to form the homogeneous mixture into pellets. Such processes are burdened with high labor and energy costs.
~ ,~
The present invention provides apparatus for blending batches of particulate material that are composi-tionally heterogeneous into batches of material that are 5 c:ompositionally uniform. The apparatus consists of two or more cylindrical static mixers, each mixer being substan-tially identical in volumetric capacity and construction.
Each mixer contains six or more vertically aligned parti-tion walls that extend radially from the midoint of the mixer to the wall to divide the mixer into at least six storage compartments of substantially equal volumetric capa-city. The vertical partition walls differ in height in a regular descending order so that as material is charged to and fills one compartment, it overflows the shorter wall to fill the adjacent compartment. One embodiment of the inven-tion includes means for feeding particulate material suc~
cessively through each of the static mixers. A second embodiment of the invention includes means for simultaneously discharging lots of particulate material from each of the mixers at a substantially uniform rate into a common con-veying means.
.
, .
1 ~ 7~64~
In the accompanying drawings:
Fig. 1 is a perspective view of a single static mixer with parts broken away.
Fig. 2 is a perspective view of two static mixers in vertical alignment, including a conduit for feeding material from the top mixer to the bottom mixer.
Fig. 3 is a top plain view of the static mixer shown in Fig. 1.
Fig. 4 is a perspective view of a second embodi-ment of a static mixer with parts broken away.
Fig. 5 shows a profile that the vertical parti-tions included in Fig. 4 would present if they were rotated counterciockwise.
Fig. 6 is a perspective view of the two static mixers in horizontal alignment, including means for feeding material from the first mixer to the second mixer.
Fig. 7 is an elevation showing the manner in which several mixers are filled and subsequently emptied onto a conveyor belt.
Fig. 8 is an enlarged view showing the manner in which the particulate maerial from the several mixers are ixed in being conveyed to a down stream packing station.
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~ 37'~fi19 As seen in ~iq. 1, the stati,c mixer has a prin-cipal section 10 of cylindrical shape which terminates in a bottom section 12 of conical shape to provide ready gravity flow of particles from the discharge port 14 of the mixer. A gate valve 15 is provided to discharge the contents from the mixer. The top 16 of the mixer is pro-vided with a product entry port 18, a vent port 20, and an access port 22 to provide entry into the mixer to make inspections and/or repairs. Suitable threaded covers 18a, 20a, and 22a are provided to seal ports 18, 20, and 22 when the mixer is not in use. The covers 20a and 22a preferably have a transparent section for visual inspection to deter-mine the level of the contents in various sections of the mixer. The interior of the mixer is provided with a series of 6 vertical partition walls 31, 32, 33, 34, 35, and 36.
The vertical interior edge of each partition wall fits tightly into channels provided in a centrally positioned vrtical rod-like member 37. The partition walls extend radially from member 37 and fit tightly against the inner wall of the mixer to subdivide the mixer into a series of 6 pie-shaped compartments _, _, c, d, , and f. The cross sectional area of each compartment is fixed by the angle defined by its 2 partition walls; these angles being defined as, respectively, C~C (31, 32) for compartment _, c~(32, 33) for compartment b, and so forth. In the embodiment shown, each of the ~Y~ angles is the same and is 60. The bot-toms of each partition wall 31, 32, 33, 34, 35, and 36 are cut to lie in a common plane (normal to the plane of gravity) which is positioned as close as practical to the discharge port 14. This construction prevents any significant upward flow from any filled compartment into any unfilled com-partment. In additon, this construction assures that the 4 '~
particles from each compartment will be discharged at a substantially uniform volumetric rate when valve 15 is opened.
In the embodiment illustrated in Fig. 1, the shape of each of partition wall 31 through 36 is identical except that each differs in height from the others. The order of the heights is such that 31 ~ 32 ~ 33 > 34 ~ 35 >
36. The partition walls are actually higher than shown in Fig. 1. They are shown in reduced height so that the dif-ferences in height are seen more easily in the perspectiveview shown. The effective depth, and thus the volumetric capacity, of each compartment a, _, c, d, _, and f is con-trolled by the height of its shorter wall. As the angles are the same for each compartment, the respective volu-metric capacity of the compartments is >f. To provide a mixer in which each compartment has eaual volumetric capacity, the partition walls should be arranged so that o~(36, 31)~ o~(35, 36)> o~ (34, 35)~ o~ (33, 34)>
c~t32, 33)~ c~(31, 32). The precise differences in the sizes of angles will be dependent upon the respective heights of the partition walls and can be readily calculated by those skilled in the art.
The apparatus of the invention shown in Fig. 2 consists of two static mixers in vertical alignment. The mixers are arranged so that a conduit 40 feeds particles discharged from the top mixer into the bottom mixer. The two mixers are identical in size and construction.
The entry port 18 of each mixer is arran~ed so that particulate matter charged to the mixer from a fill tube 42 flows directly into compartment _. When compart-ment _ is filled, additional material charged to the mixer overflows partition wall 32 and falls into compartment b.
As the filling action is continued, particulate matter successively and sequentially overflows partition walls 33, 34, 35, and 36 to fill compartments c, _, _, and f. The respective heights of partition walls 31, 32, 33, 34, 35, and 36 will be fixed to assure that the compartments of the mixer are filled in this order. In particular, the partition wall 31 will extend to the top of the mixer to prevent any overflow of material from compartment a into compartment f. The entry port 18 of the bottom mixer also is positioned so that the particles discharged from the top mixer through conduit 40 and fill tube 42 flow directly into compartment _ and successively fill compart-ments a, b, c, _, _, and f, as previously described.
The apparatus shown in Fig. 6 is similar to that shown in Fig. 2, except that the two static mixers are positioned in horizontal alignment rather than in vertical alignment. The construction of the mixers and their opera-tion are essentially similar to that shown in Fig. 2, except for the means included to transfer particulate matter from the first mixer to the second mixer. The product discharged from the first mixer into conduit 40 flows into a transfer line 44. Air admitted into line 44 through valve 46 blows the discharged particulate matter from the first mixer through line 44 into the second mixer. In lieu of employ-ing a simple gate valve in the first mixer, it is desirable to employ a rotary feeder valve to provide a positive dis-charge of product when air pressure is applied to line 44.
Fig. 4 illustrates a modification of the mixer of Fig. 1 in which like parts bear identifying numbers 100 units higher than the corresponding parts shown in Fig. 1.
Partition wall 131 has the same shape as corresponding wall 31 shown in Fig. 1 and extends to the top of the mixer.
The top edge of each of the other partition walls 132, 133, 134, 135, and 136 is cut so that it either slopes from its midsection (i.e., the section that fits in member 137) to its wall section (i.e., the section that touches the inner mixer wall) or from its wall section to its midsection.
g The top edges of partition walls 133 and 135 slope from their midsections to their wall sections. The top sur-faces of partition walls 132, 135, and 136 slope in the opposite direction, i.e., from their wall sections to their midsections. Normal lines drawn from the point at which partition walls 133 and 135 touch the inner mixer wall to rod member 137 define acute angles s. Similarly, normal lines drawn from the point at which the partition walls 132, 134, and 136 touch rod member 137 to the inner mixer wall define acute angles B. Typically, angles B are approximately 15. If the partition walls were rotated counterclockwise, the top surfaces of the partition walls would show the cascading profile shown in Fig. 5. This construction provides easier overflow of particles from one compartment to the next compartment.
While the drawings illustrate mixers having 6 partition walls which divide the interior of the mixer into 6 compartments of substantially equal volumetric capa-city, it is feasible to provide 7 or more partition walls to divide the mixer into 7 or more compartments. It has been the inventor's experience that 6 compartment mixers povide adequate mixing for most purposes when 2 mixers are employed. Where mixing of extremely heterogeneous mate-rials is required, somewhat improved results are obtained when a third mixer is included in the apparatus of the invention.
The specific heights of the partition walls in the mixers will be somewhat dependent upon the flow charac-teristics of the materials to be blended in the mixers.
The flow characteristics of particulate materials are pro-portional to their angles of repose. For many materials, such angles are known and reported in the literature.
. , Where such angles are not known, they can be readily deter-mined by known methods. The required differentials in height between adjacent partition walls will be directly proportional to the angles of repose of the materials to be blended. The highest of the partition walls should extend to the top of the mixer. This will prevent any flow of charged material to the last of the concentrically arranged storage compartments. Each of the remaining partition walls should have its height reduced by the amount required to provide ready overflow from one filled storage compartment to the adjacent unfilled compartment.
The embodiment of Fig. 2 shows the two mixers in direct vertical alignment. The arrangement has a minimum space requirement, but requires that the transfer conduit 40 to be positioned at an angle from the field of gravity.
When adequate space is available, the lower mixer can be offset somewhat from the first mixer to provide a direct drop from the discharge port of the top mixer to the entry port of the bottom mixer.
To provide optimum mixing efficiency in use, each of the mixers should be completely emptied before the mate-rial to be blended is charged thereto. The volume of each batch of particulate material to be used should be, to the extent practical, precisely equal to the volumetric storage capacity of the several storage compartments.* It will be recognized that some free space will remain above each of the storage compartments. If the batch to be blended is larger than the storage capacity of the several compartments, *In subsequent discussions, the total capacity of the several compartments will be referred to as the mixer's "effective capacity."
1 ~ 7~49 , the excess particulate material will occupy a portion of the designed free space provided in the mixer. As the con-tent of each of the individual storage compartments is discharged at the same rate, any excess material initially occupying the designed free space will not be mixed with any of the material stored in the storage compartments.
In situations where undersized batches of mate-rial require blending, the batch size should be selected to completely fill 2, 3, or more compartments of the mixers.
Such undersized batches, in a single pass through the apparatus, will not be as well blended as full size batches.
If a more homogeneous blend is required, such undersized batches should be passed through the apparatus two or more times.
Where it is desired to prepare a blend from 2 or more batches of particulate material, the precise order in which the batches are charged to the top mixer ordinarily is not critical. It is preferred, however, to charge each batch to the mixer in sequence. By operating in this manner, each batch will be concentrated in one or more compartments in the top mixer. When the contents are discharged from the top mixer, it will be well blended with the contents of the other compartments. The same mixing action takes place in the lower mixer(s) and it is readily seen that the final ` 25 lot of material discharged from the bottommost mlxer will be homogeneously blended.
The apparatus is well suited to prepare blends of an additive with particulate polymer at law cost. A typical blend that can be prepared is polyethylene containing a - 30 slip agent such as erucamide. In an initial step, the erucamide will be dispersed in polyethylene pellets at a concentration significantly higher than desired in the resin to be delivered to the customer. For purposes of illus-` tration only, the additive concentration will be six times .
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the concentration desired in the final product. This con-centrate will be prepared by any desired method as by compounding in an estruder. A lot of this polymer con-centrate having a volume equivalent to one-sixth of the mixer's effective capacity will be charged to the top mixer.
When employing the apparatus illustrated in Figs. 1 and 2, the concentrate will completely fill compartment a. A
second lot of the polymer containing no erucamide, having a volume equivalent to five-sixths of the mixer's effective capacity then will be charged to the top mixer. The additive-free resin will completely fill compartments _, c, _, e, and f. When valve 15 of the top mixer is opened, the contents of each compartment a, _, c, d, e, and f are discharged at essentially equivalent volumetric rates.
Thus the particles flowing through conduit 40 into the second mixer will contain, on an average, equal volumes of ~ar-ticles from each compartment of the top mixer.
As the particles from the top mixer flow into the second mixer, each compartment will be filled with a mix-ture containing on a volume basis, one part of the concen-trate and five parts of the additive-free polymer. Any deviations from the desired 1:5 ratio will be small. When the final blend is discharged from the bottom mixer, the uniformity of the blend will be further enhanced. The final product will contain 1 particle of concentrate for each 5 particles of additive-free polymer. When this prod-uct is extruded by the ultimate user, the melt mixing in the extruder will provide film having the erucamide suffi-ciently well distributed throughout the film to be suit-able for nearly all purposes.
In preparing a mixture of polymer products, a manufacturer frequently is faced with the problem of pre-paring a series of related polymers containing two additives, ! '~ 7 ~ 9 one of which is common to the entire family ~ products and the second of which is specific for the individual polymer products. A typical series of polymer products of this type are film grade polymers containing a slip agent such as erucamide and a specific colorant for each polymer prod-uct. To prepare such a-series of polymer products, a first polymer master batch containing erucamide will be prepared as previously described. A master batch also will be pre-pared for each polymer product and will contain the colorant at a concentration substantially six times the concentration desired in the finished product. The top mixer will be first charged with one of the master batches and then the second master batch. This charging order will fill compartment _ with one master batch and compartment b with the second master batch. The mixer then is filled with uncompounded or additive-free polymer. When the valve 15 of the top mixer is open, the contents of each compartment a, , c, d, _, and f are discharged at essentially equivalent volu-metric rates. The particles flowing through conduit 40 into the second mixer will contain, on an average, one volume part of the first master batch, one volume part of the second master batch, and four volume parts of the uncompounded or additive-free polymer.
As noted from the above descriptions, in preparing batches of polymer particles having additives mixed there-with, the first essential step is to prepare a polymer mas-` ter batch of the desired additive(s) at a concentration such that the master batch will be included in the final batch in a volumetric proportion such that the master batch will fill one or an even number of compartments of the top mixer.The master batch containing the additive should be charged ~ ii 7~9 to the first mixer in such a manner as to be contained entirely within one or an even number of the compartments of the mixer. This is done most conveniently by charging the master batch to the mixer prior to charging the uncom-pounded or additive-free polymer to the mixer.
Another application of the apparatus of the inven-tion is to increase the homogeneity of a batch of polymer particles which for any reason are more heterogeneous in composition than desired. Again, in the manufacture of polyethylene by high pressure autoclave process, it is some-times noted that undesirably wide fluctuations of melt index are present in the product exiting the reactor. By passing such batches of polymer through the apparatus of the inven-tion, the various segments of the initial batch become blended so that the entire batch of polymer discharged from the bottommost mixer is more homogeneous with respect to melt index.
Fig. 7 shows five (5) mixers 1, 2, 3, 4, and 5 arranged in horizontal alignment. Each mixer is identical in size and construction. A product delivery line 50 fitted with valves 52 feeds particulate polymer to the mixers via lines 54. As subsequently described, each mixer is filled in~sequence. At the time of discharge, valves 15 of each of mixers l, 2, 3, 4, and 5 are opened simultaneously 50 as to discharge the particulate polymer onto an endless con-veyor belt 60. Fig. 8 illustrates that the product from the several mixers forms layers on the belt 60 with layer a being the product discharged from-mixer 1, layer b being the product discharged from mixer 2, and so forth. The par-i~ 30 ticulate product is discharged from belt 60 to a packaaing station not shown.
~ 1 ~ r`1 ~ 6 ~ '~
In operation of the embodiment illustrated in F:Lg. 7, each of mixers 1, 2, 3, 4, and 5 will be empty at the beginning of the operational cycle. Particulate poly-mer, such as pelleted polyethylene, is fed via line 50 to the first valve 52 and through the 'irst line 54. This material begins to fill compartment a of mixer 1. After compartment a is filled, the polymer particles flowing into mixer 1 overflow wall 32 and begin filling compartment b.
This action is continued until each of the compartments of mixer 1 is filled. The flow of the particulate polymer to mixer 1 will be measured and first valve 52 will be closed at the appropriate time so that the volume of particulate polymer charged will be, to the extent practical, pre-cisely equal the volumetric storage capacity of the several storage compartments of the mixer. It will be recognized that some free space will remain above each of the storage compartments of the mixer. This is desirable for reasons discussed supra. After mixer 1 is filled, mixers 2, 3, 4, and 5 will be filled in sequence in the same manner.
After all of the mixers have been filled, the con-veyor belt 60 is started and the valves 15 of each of mixers 1, 2, 3, 4, and 5 are opened simultaneously and product from each mixer is discharged through lines 56.
The product being discharged from each mixer will contain an equal volume fraction from each of storage compartments a, _, c, _, _, and f. It is thus seen that the product being discharged, by reason of containing an equal volume frac-tion from each of the storage compartments, blends parti-culate polymer produced over a significant time period and tends to even out periodic variations in product properties such as melt index.
. ;, ~, I ~, 3~j~g ..
As illustrated in Fig. 8, the particulate polymer tends to form layers a, b, c, d, and e on conveyor belt 60.
Each layer of course is homogeneous by reason of being a blend formed by mixing material from the six storage com-partments of each mixer. When the material is dischargedfrom the conveyor belt to the packaging station not shown, the material in each of the layers a, b, c, d, and e becomes intimately mixed. Thus the material that is packaged and delivered to the user is made up of substantially equal proportions of material from each of the 30 storage compart-ments in the five mixers illustrated. Accordingly, the periodic variations in polymer properties are evened out.
If desired, the apparatus of Fig. 7 can be modi-fied by employing a pneumatic conveying system in lieu of the conveyor belt shown. In this embodiment of the inven-ton, lines 56 are connected to a large capacity pneumatic conveying line. Gate valves 15 are replaced with rotary feeders which function as discharge valves.
The apparatus and method of the invention are par-ticularly well suited for the manufacture of large batches of particular polymers. By way of example, by employing a series of five bins, each of which contains an effective volumetric capacity of about 6,500 ft3 (184 m3),it is pos-sible to prepare single uniform batches of one million pounds (472,000 kilos) of polyethylene. These figures are based upon the consideration that the density of polyethy-lene pellets is about 32 lbs/ft3 (513 kilos/m3). ~torage bins of this capacity are easily manufactured. The bins should be constructed to discharge product at a rate of at lease about 650 ft3~hour (18.4 m3/hour~.
While the use of the appratus has been described to prepare compositionally uniform blends of particulate polymers, it obviously can be used to prepare uniform blends of other types of particulate products.
In the manufacture of particulate materials such as thermoplastic polymers, e.g., high pressure polyethy-lene, it is observed that certain lots will have a desired property such as melt index which falls outside of product specifications. To provide a maximum percentage of product falling within product specifications, the manufacturer will blend a product lot having an undesirably high melt index with a product lot having an undesirably low melt index.
The resulting mixed lot will have a melt index within spe-cifications. Such lots customarily are mixed in rotary mixers and/or remelted and extruded. Such reprocessing entails high labor costs and, in addition, high energy costs when an extrusion step is employed.
In incorporating additives such as slip agents, antiblock agents, and the like into such resins, it is custo-mary to first prepare dry blends of the resin and addi-tive(s) and then extrude the dry blend to form the homogeneous mixture into pellets. Such processes are burdened with high labor and energy costs.
~ ,~
The present invention provides apparatus for blending batches of particulate material that are composi-tionally heterogeneous into batches of material that are 5 c:ompositionally uniform. The apparatus consists of two or more cylindrical static mixers, each mixer being substan-tially identical in volumetric capacity and construction.
Each mixer contains six or more vertically aligned parti-tion walls that extend radially from the midoint of the mixer to the wall to divide the mixer into at least six storage compartments of substantially equal volumetric capa-city. The vertical partition walls differ in height in a regular descending order so that as material is charged to and fills one compartment, it overflows the shorter wall to fill the adjacent compartment. One embodiment of the inven-tion includes means for feeding particulate material suc~
cessively through each of the static mixers. A second embodiment of the invention includes means for simultaneously discharging lots of particulate material from each of the mixers at a substantially uniform rate into a common con-veying means.
.
, .
1 ~ 7~64~
In the accompanying drawings:
Fig. 1 is a perspective view of a single static mixer with parts broken away.
Fig. 2 is a perspective view of two static mixers in vertical alignment, including a conduit for feeding material from the top mixer to the bottom mixer.
Fig. 3 is a top plain view of the static mixer shown in Fig. 1.
Fig. 4 is a perspective view of a second embodi-ment of a static mixer with parts broken away.
Fig. 5 shows a profile that the vertical parti-tions included in Fig. 4 would present if they were rotated counterciockwise.
Fig. 6 is a perspective view of the two static mixers in horizontal alignment, including means for feeding material from the first mixer to the second mixer.
Fig. 7 is an elevation showing the manner in which several mixers are filled and subsequently emptied onto a conveyor belt.
Fig. 8 is an enlarged view showing the manner in which the particulate maerial from the several mixers are ixed in being conveyed to a down stream packing station.
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~ 37'~fi19 As seen in ~iq. 1, the stati,c mixer has a prin-cipal section 10 of cylindrical shape which terminates in a bottom section 12 of conical shape to provide ready gravity flow of particles from the discharge port 14 of the mixer. A gate valve 15 is provided to discharge the contents from the mixer. The top 16 of the mixer is pro-vided with a product entry port 18, a vent port 20, and an access port 22 to provide entry into the mixer to make inspections and/or repairs. Suitable threaded covers 18a, 20a, and 22a are provided to seal ports 18, 20, and 22 when the mixer is not in use. The covers 20a and 22a preferably have a transparent section for visual inspection to deter-mine the level of the contents in various sections of the mixer. The interior of the mixer is provided with a series of 6 vertical partition walls 31, 32, 33, 34, 35, and 36.
The vertical interior edge of each partition wall fits tightly into channels provided in a centrally positioned vrtical rod-like member 37. The partition walls extend radially from member 37 and fit tightly against the inner wall of the mixer to subdivide the mixer into a series of 6 pie-shaped compartments _, _, c, d, , and f. The cross sectional area of each compartment is fixed by the angle defined by its 2 partition walls; these angles being defined as, respectively, C~C (31, 32) for compartment _, c~(32, 33) for compartment b, and so forth. In the embodiment shown, each of the ~Y~ angles is the same and is 60. The bot-toms of each partition wall 31, 32, 33, 34, 35, and 36 are cut to lie in a common plane (normal to the plane of gravity) which is positioned as close as practical to the discharge port 14. This construction prevents any significant upward flow from any filled compartment into any unfilled com-partment. In additon, this construction assures that the 4 '~
particles from each compartment will be discharged at a substantially uniform volumetric rate when valve 15 is opened.
In the embodiment illustrated in Fig. 1, the shape of each of partition wall 31 through 36 is identical except that each differs in height from the others. The order of the heights is such that 31 ~ 32 ~ 33 > 34 ~ 35 >
36. The partition walls are actually higher than shown in Fig. 1. They are shown in reduced height so that the dif-ferences in height are seen more easily in the perspectiveview shown. The effective depth, and thus the volumetric capacity, of each compartment a, _, c, d, _, and f is con-trolled by the height of its shorter wall. As the angles are the same for each compartment, the respective volu-metric capacity of the compartments is >f. To provide a mixer in which each compartment has eaual volumetric capacity, the partition walls should be arranged so that o~(36, 31)~ o~(35, 36)> o~ (34, 35)~ o~ (33, 34)>
c~t32, 33)~ c~(31, 32). The precise differences in the sizes of angles will be dependent upon the respective heights of the partition walls and can be readily calculated by those skilled in the art.
The apparatus of the invention shown in Fig. 2 consists of two static mixers in vertical alignment. The mixers are arranged so that a conduit 40 feeds particles discharged from the top mixer into the bottom mixer. The two mixers are identical in size and construction.
The entry port 18 of each mixer is arran~ed so that particulate matter charged to the mixer from a fill tube 42 flows directly into compartment _. When compart-ment _ is filled, additional material charged to the mixer overflows partition wall 32 and falls into compartment b.
As the filling action is continued, particulate matter successively and sequentially overflows partition walls 33, 34, 35, and 36 to fill compartments c, _, _, and f. The respective heights of partition walls 31, 32, 33, 34, 35, and 36 will be fixed to assure that the compartments of the mixer are filled in this order. In particular, the partition wall 31 will extend to the top of the mixer to prevent any overflow of material from compartment a into compartment f. The entry port 18 of the bottom mixer also is positioned so that the particles discharged from the top mixer through conduit 40 and fill tube 42 flow directly into compartment _ and successively fill compart-ments a, b, c, _, _, and f, as previously described.
The apparatus shown in Fig. 6 is similar to that shown in Fig. 2, except that the two static mixers are positioned in horizontal alignment rather than in vertical alignment. The construction of the mixers and their opera-tion are essentially similar to that shown in Fig. 2, except for the means included to transfer particulate matter from the first mixer to the second mixer. The product discharged from the first mixer into conduit 40 flows into a transfer line 44. Air admitted into line 44 through valve 46 blows the discharged particulate matter from the first mixer through line 44 into the second mixer. In lieu of employ-ing a simple gate valve in the first mixer, it is desirable to employ a rotary feeder valve to provide a positive dis-charge of product when air pressure is applied to line 44.
Fig. 4 illustrates a modification of the mixer of Fig. 1 in which like parts bear identifying numbers 100 units higher than the corresponding parts shown in Fig. 1.
Partition wall 131 has the same shape as corresponding wall 31 shown in Fig. 1 and extends to the top of the mixer.
The top edge of each of the other partition walls 132, 133, 134, 135, and 136 is cut so that it either slopes from its midsection (i.e., the section that fits in member 137) to its wall section (i.e., the section that touches the inner mixer wall) or from its wall section to its midsection.
g The top edges of partition walls 133 and 135 slope from their midsections to their wall sections. The top sur-faces of partition walls 132, 135, and 136 slope in the opposite direction, i.e., from their wall sections to their midsections. Normal lines drawn from the point at which partition walls 133 and 135 touch the inner mixer wall to rod member 137 define acute angles s. Similarly, normal lines drawn from the point at which the partition walls 132, 134, and 136 touch rod member 137 to the inner mixer wall define acute angles B. Typically, angles B are approximately 15. If the partition walls were rotated counterclockwise, the top surfaces of the partition walls would show the cascading profile shown in Fig. 5. This construction provides easier overflow of particles from one compartment to the next compartment.
While the drawings illustrate mixers having 6 partition walls which divide the interior of the mixer into 6 compartments of substantially equal volumetric capa-city, it is feasible to provide 7 or more partition walls to divide the mixer into 7 or more compartments. It has been the inventor's experience that 6 compartment mixers povide adequate mixing for most purposes when 2 mixers are employed. Where mixing of extremely heterogeneous mate-rials is required, somewhat improved results are obtained when a third mixer is included in the apparatus of the invention.
The specific heights of the partition walls in the mixers will be somewhat dependent upon the flow charac-teristics of the materials to be blended in the mixers.
The flow characteristics of particulate materials are pro-portional to their angles of repose. For many materials, such angles are known and reported in the literature.
. , Where such angles are not known, they can be readily deter-mined by known methods. The required differentials in height between adjacent partition walls will be directly proportional to the angles of repose of the materials to be blended. The highest of the partition walls should extend to the top of the mixer. This will prevent any flow of charged material to the last of the concentrically arranged storage compartments. Each of the remaining partition walls should have its height reduced by the amount required to provide ready overflow from one filled storage compartment to the adjacent unfilled compartment.
The embodiment of Fig. 2 shows the two mixers in direct vertical alignment. The arrangement has a minimum space requirement, but requires that the transfer conduit 40 to be positioned at an angle from the field of gravity.
When adequate space is available, the lower mixer can be offset somewhat from the first mixer to provide a direct drop from the discharge port of the top mixer to the entry port of the bottom mixer.
To provide optimum mixing efficiency in use, each of the mixers should be completely emptied before the mate-rial to be blended is charged thereto. The volume of each batch of particulate material to be used should be, to the extent practical, precisely equal to the volumetric storage capacity of the several storage compartments.* It will be recognized that some free space will remain above each of the storage compartments. If the batch to be blended is larger than the storage capacity of the several compartments, *In subsequent discussions, the total capacity of the several compartments will be referred to as the mixer's "effective capacity."
1 ~ 7~49 , the excess particulate material will occupy a portion of the designed free space provided in the mixer. As the con-tent of each of the individual storage compartments is discharged at the same rate, any excess material initially occupying the designed free space will not be mixed with any of the material stored in the storage compartments.
In situations where undersized batches of mate-rial require blending, the batch size should be selected to completely fill 2, 3, or more compartments of the mixers.
Such undersized batches, in a single pass through the apparatus, will not be as well blended as full size batches.
If a more homogeneous blend is required, such undersized batches should be passed through the apparatus two or more times.
Where it is desired to prepare a blend from 2 or more batches of particulate material, the precise order in which the batches are charged to the top mixer ordinarily is not critical. It is preferred, however, to charge each batch to the mixer in sequence. By operating in this manner, each batch will be concentrated in one or more compartments in the top mixer. When the contents are discharged from the top mixer, it will be well blended with the contents of the other compartments. The same mixing action takes place in the lower mixer(s) and it is readily seen that the final ` 25 lot of material discharged from the bottommost mlxer will be homogeneously blended.
The apparatus is well suited to prepare blends of an additive with particulate polymer at law cost. A typical blend that can be prepared is polyethylene containing a - 30 slip agent such as erucamide. In an initial step, the erucamide will be dispersed in polyethylene pellets at a concentration significantly higher than desired in the resin to be delivered to the customer. For purposes of illus-` tration only, the additive concentration will be six times .
.
the concentration desired in the final product. This con-centrate will be prepared by any desired method as by compounding in an estruder. A lot of this polymer con-centrate having a volume equivalent to one-sixth of the mixer's effective capacity will be charged to the top mixer.
When employing the apparatus illustrated in Figs. 1 and 2, the concentrate will completely fill compartment a. A
second lot of the polymer containing no erucamide, having a volume equivalent to five-sixths of the mixer's effective capacity then will be charged to the top mixer. The additive-free resin will completely fill compartments _, c, _, e, and f. When valve 15 of the top mixer is opened, the contents of each compartment a, _, c, d, e, and f are discharged at essentially equivalent volumetric rates.
Thus the particles flowing through conduit 40 into the second mixer will contain, on an average, equal volumes of ~ar-ticles from each compartment of the top mixer.
As the particles from the top mixer flow into the second mixer, each compartment will be filled with a mix-ture containing on a volume basis, one part of the concen-trate and five parts of the additive-free polymer. Any deviations from the desired 1:5 ratio will be small. When the final blend is discharged from the bottom mixer, the uniformity of the blend will be further enhanced. The final product will contain 1 particle of concentrate for each 5 particles of additive-free polymer. When this prod-uct is extruded by the ultimate user, the melt mixing in the extruder will provide film having the erucamide suffi-ciently well distributed throughout the film to be suit-able for nearly all purposes.
In preparing a mixture of polymer products, a manufacturer frequently is faced with the problem of pre-paring a series of related polymers containing two additives, ! '~ 7 ~ 9 one of which is common to the entire family ~ products and the second of which is specific for the individual polymer products. A typical series of polymer products of this type are film grade polymers containing a slip agent such as erucamide and a specific colorant for each polymer prod-uct. To prepare such a-series of polymer products, a first polymer master batch containing erucamide will be prepared as previously described. A master batch also will be pre-pared for each polymer product and will contain the colorant at a concentration substantially six times the concentration desired in the finished product. The top mixer will be first charged with one of the master batches and then the second master batch. This charging order will fill compartment _ with one master batch and compartment b with the second master batch. The mixer then is filled with uncompounded or additive-free polymer. When the valve 15 of the top mixer is open, the contents of each compartment a, , c, d, _, and f are discharged at essentially equivalent volu-metric rates. The particles flowing through conduit 40 into the second mixer will contain, on an average, one volume part of the first master batch, one volume part of the second master batch, and four volume parts of the uncompounded or additive-free polymer.
As noted from the above descriptions, in preparing batches of polymer particles having additives mixed there-with, the first essential step is to prepare a polymer mas-` ter batch of the desired additive(s) at a concentration such that the master batch will be included in the final batch in a volumetric proportion such that the master batch will fill one or an even number of compartments of the top mixer.The master batch containing the additive should be charged ~ ii 7~9 to the first mixer in such a manner as to be contained entirely within one or an even number of the compartments of the mixer. This is done most conveniently by charging the master batch to the mixer prior to charging the uncom-pounded or additive-free polymer to the mixer.
Another application of the apparatus of the inven-tion is to increase the homogeneity of a batch of polymer particles which for any reason are more heterogeneous in composition than desired. Again, in the manufacture of polyethylene by high pressure autoclave process, it is some-times noted that undesirably wide fluctuations of melt index are present in the product exiting the reactor. By passing such batches of polymer through the apparatus of the inven-tion, the various segments of the initial batch become blended so that the entire batch of polymer discharged from the bottommost mixer is more homogeneous with respect to melt index.
Fig. 7 shows five (5) mixers 1, 2, 3, 4, and 5 arranged in horizontal alignment. Each mixer is identical in size and construction. A product delivery line 50 fitted with valves 52 feeds particulate polymer to the mixers via lines 54. As subsequently described, each mixer is filled in~sequence. At the time of discharge, valves 15 of each of mixers l, 2, 3, 4, and 5 are opened simultaneously 50 as to discharge the particulate polymer onto an endless con-veyor belt 60. Fig. 8 illustrates that the product from the several mixers forms layers on the belt 60 with layer a being the product discharged from-mixer 1, layer b being the product discharged from mixer 2, and so forth. The par-i~ 30 ticulate product is discharged from belt 60 to a packaaing station not shown.
~ 1 ~ r`1 ~ 6 ~ '~
In operation of the embodiment illustrated in F:Lg. 7, each of mixers 1, 2, 3, 4, and 5 will be empty at the beginning of the operational cycle. Particulate poly-mer, such as pelleted polyethylene, is fed via line 50 to the first valve 52 and through the 'irst line 54. This material begins to fill compartment a of mixer 1. After compartment a is filled, the polymer particles flowing into mixer 1 overflow wall 32 and begin filling compartment b.
This action is continued until each of the compartments of mixer 1 is filled. The flow of the particulate polymer to mixer 1 will be measured and first valve 52 will be closed at the appropriate time so that the volume of particulate polymer charged will be, to the extent practical, pre-cisely equal the volumetric storage capacity of the several storage compartments of the mixer. It will be recognized that some free space will remain above each of the storage compartments of the mixer. This is desirable for reasons discussed supra. After mixer 1 is filled, mixers 2, 3, 4, and 5 will be filled in sequence in the same manner.
After all of the mixers have been filled, the con-veyor belt 60 is started and the valves 15 of each of mixers 1, 2, 3, 4, and 5 are opened simultaneously and product from each mixer is discharged through lines 56.
The product being discharged from each mixer will contain an equal volume fraction from each of storage compartments a, _, c, _, _, and f. It is thus seen that the product being discharged, by reason of containing an equal volume frac-tion from each of the storage compartments, blends parti-culate polymer produced over a significant time period and tends to even out periodic variations in product properties such as melt index.
. ;, ~, I ~, 3~j~g ..
As illustrated in Fig. 8, the particulate polymer tends to form layers a, b, c, d, and e on conveyor belt 60.
Each layer of course is homogeneous by reason of being a blend formed by mixing material from the six storage com-partments of each mixer. When the material is dischargedfrom the conveyor belt to the packaging station not shown, the material in each of the layers a, b, c, d, and e becomes intimately mixed. Thus the material that is packaged and delivered to the user is made up of substantially equal proportions of material from each of the 30 storage compart-ments in the five mixers illustrated. Accordingly, the periodic variations in polymer properties are evened out.
If desired, the apparatus of Fig. 7 can be modi-fied by employing a pneumatic conveying system in lieu of the conveyor belt shown. In this embodiment of the inven-ton, lines 56 are connected to a large capacity pneumatic conveying line. Gate valves 15 are replaced with rotary feeders which function as discharge valves.
The apparatus and method of the invention are par-ticularly well suited for the manufacture of large batches of particular polymers. By way of example, by employing a series of five bins, each of which contains an effective volumetric capacity of about 6,500 ft3 (184 m3),it is pos-sible to prepare single uniform batches of one million pounds (472,000 kilos) of polyethylene. These figures are based upon the consideration that the density of polyethy-lene pellets is about 32 lbs/ft3 (513 kilos/m3). ~torage bins of this capacity are easily manufactured. The bins should be constructed to discharge product at a rate of at lease about 650 ft3~hour (18.4 m3/hour~.
While the use of the appratus has been described to prepare compositionally uniform blends of particulate polymers, it obviously can be used to prepare uniform blends of other types of particulate products.
Claims (14)
OR PROPERTY IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for blending flowable particles consisting essentially of:
A. A plurality of static mixers of essentially cylindrical shape; each mixer being substantially identical in volumetric capacity and con-struction, each mixer including;
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to pro-vide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the angles formed between each adjacent pair of partition walls being sub-tially equal so that each storage com-partment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each stor-age compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, and (6) an inlet port in the top of the mixer and posi-tioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest vertical par-tition walls, and B. Means for feeding flowable particles successively through each of the static mixers;
or B'. Means for simultaneously discharging lots of flow-able particles from each of the mixers of (A) at a substantially uniform rate into a common con-veying means.
A. A plurality of static mixers of essentially cylindrical shape; each mixer being substantially identical in volumetric capacity and con-struction, each mixer including;
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to pro-vide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the angles formed between each adjacent pair of partition walls being sub-tially equal so that each storage com-partment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each stor-age compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, and (6) an inlet port in the top of the mixer and posi-tioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest vertical par-tition walls, and B. Means for feeding flowable particles successively through each of the static mixers;
or B'. Means for simultaneously discharging lots of flow-able particles from each of the mixers of (A) at a substantially uniform rate into a common con-veying means.
2. Apparatus for blending flowable particles consisting essentially of:
A. A plurality of static mixers of essentially cylin-drical shape, each mixer being substantially identical in volumetric capacity and construction;
each mixer including;
(1) a principal section that is essentially cylin-drical in shape, (2) a bottom section of conical shape to provide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical par-tition walls being further characterized in that;
(a) the partition walls are of spirally;
descending height, (b) the angles formed between each adjacent pair of partition walls being substan-tially equal so that each storage compartment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, (6) an inlet port in the top of the mixer and positioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest vertical partition walls, and B. Means for feeding flowable particles successively through each of the static mixers.
A. A plurality of static mixers of essentially cylin-drical shape, each mixer being substantially identical in volumetric capacity and construction;
each mixer including;
(1) a principal section that is essentially cylin-drical in shape, (2) a bottom section of conical shape to provide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical par-tition walls being further characterized in that;
(a) the partition walls are of spirally;
descending height, (b) the angles formed between each adjacent pair of partition walls being substan-tially equal so that each storage compartment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, (6) an inlet port in the top of the mixer and positioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest vertical partition walls, and B. Means for feeding flowable particles successively through each of the static mixers.
3. Apparatus for blending flowable particles consisting essentially of:
A. A plurality of static mixers of essentially cylin-drical shape, each mixer being substantially identical in volumetric capacity and construc-tion, each mixer including;
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to pro-vide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the angles formed between each adjacent pair of partition walls being substan-tially equal so that each storage compartment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each stor-age compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the dis-charge port, the bottom construction of the partition walls being such that particles flow by gravity at substan-tially equal volumetric rates from each compartment when the valve of the discharge port is opened, (6) an inlet port in the top of the mixer and positioned so that particles fed there-through flow by gravity directly into the compartment defined by the first and second highest vertical partition walls, and B. Means for simultaneously discharging lots of flowable particles from each of the mixers of (A) into a common conveying means.
A. A plurality of static mixers of essentially cylin-drical shape, each mixer being substantially identical in volumetric capacity and construc-tion, each mixer including;
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to pro-vide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the angles formed between each adjacent pair of partition walls being substan-tially equal so that each storage compartment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each stor-age compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the dis-charge port, the bottom construction of the partition walls being such that particles flow by gravity at substan-tially equal volumetric rates from each compartment when the valve of the discharge port is opened, (6) an inlet port in the top of the mixer and positioned so that particles fed there-through flow by gravity directly into the compartment defined by the first and second highest vertical partition walls, and B. Means for simultaneously discharging lots of flowable particles from each of the mixers of (A) into a common conveying means.
4. Apparatus of claim 2 in which the mixers are positioned in vertical alignment so that product discharged from the top mixer flows by gravity into the second mixer.
5. Apparatus of claim 2 in which the mixers are posi-tioned in horizontal alignment.
6. Apparatus of claim 3 in which:
A. The mixers are positioned in horizontal align-ment, B. A common feed line feeds flowable particles to each of the mixers, and C. Conveying means runs under each of the mixers of (A) to receive flowable particles discharged therefrom.
A. The mixers are positioned in horizontal align-ment, B. A common feed line feeds flowable particles to each of the mixers, and C. Conveying means runs under each of the mixers of (A) to receive flowable particles discharged therefrom.
7. Apparatus of claim 3 or claim 6, having at least five (5) mixers.
8. Apparatus of claim ], claim 2 or claim 3, in which each mixer has an effective storage capacity of at least about 184M3.
9. Apparatus of claim 1, claim 2 or claim 3, in which each mixer is further characterized in that flowable particles can be discharged therefrom at a rate of at least about 18.4M3/hour.
10. A method for preparing a batch of polymer particles having an additive substantially uniformly dis-tributed therethrough, which consists essentially of:
A. Blending said additive with an aliquot the batch of polymer particles, B. Sequentially charging, in any order, the aliquot of step (A) and the balance of the batch of said polymer particles to a first empty static mixer characterized in having;
(1) a principal section of generally cylin-drical shape fitted with a conically shaped bottom section to provide ready gravity flow of particles from said mixer, (2) a centrally positioned discharge port in the bottom of the mixer, (3) a valve in said discharge port, (4) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall and divides the mixer into at least six storage compartments of sub-stantially equal volumetric capacity, said partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the differences in height of the parti-tion walls are such as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (c) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volu-metric rates from each compartment when the valve of the discharge port is opened, (5) an inlet port in the top of the mixer and positioned so that particles fed there-through flow directly by gravity into the compartment defined by the first and second highest vertical partition walls, C. Discharging the entire contents of said first static mixer through its discharge port and feed-ing said discharged material into the inlet port of a second static mixer; the volumetric capacity and construction of said second mixer being sub-stantially identical to that of said first mixer, and D. Discharging the entire contents of said second static mixer and recovering a batch of polymer particles having said additive substantially uni-formly distributed throughout said batch;
said process further characterized that the volumetric size of said batch of polymer particles and additive is such that it completely fills each storage com-partment of said static mixers.
A. Blending said additive with an aliquot the batch of polymer particles, B. Sequentially charging, in any order, the aliquot of step (A) and the balance of the batch of said polymer particles to a first empty static mixer characterized in having;
(1) a principal section of generally cylin-drical shape fitted with a conically shaped bottom section to provide ready gravity flow of particles from said mixer, (2) a centrally positioned discharge port in the bottom of the mixer, (3) a valve in said discharge port, (4) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall and divides the mixer into at least six storage compartments of sub-stantially equal volumetric capacity, said partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the differences in height of the parti-tion walls are such as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (c) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volu-metric rates from each compartment when the valve of the discharge port is opened, (5) an inlet port in the top of the mixer and positioned so that particles fed there-through flow directly by gravity into the compartment defined by the first and second highest vertical partition walls, C. Discharging the entire contents of said first static mixer through its discharge port and feed-ing said discharged material into the inlet port of a second static mixer; the volumetric capacity and construction of said second mixer being sub-stantially identical to that of said first mixer, and D. Discharging the entire contents of said second static mixer and recovering a batch of polymer particles having said additive substantially uni-formly distributed throughout said batch;
said process further characterized that the volumetric size of said batch of polymer particles and additive is such that it completely fills each storage com-partment of said static mixers.
11. A process for increasing the homogeneity of a batch of polymer particles which is heterogeneous in com-position, which consists essentially of:
A. Charging the entire batch of polymer particles to a first empty static mixer characterized in having;
(1) a prinicpal section of generally cylin-drical shape fitted with a conically shaped bottom section to provide ready gravity flow of particles from said mixer, (2) a centrally positioned discharge port in the bottom of the mixer, (3) a valve in said discharge port, (4) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall and divides the mixer into at least six storage compartments of sub-stantially equal volumetric capacity, said partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the differences in height of the parti-tion walls are such that as each stor-age compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (c) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, (5) an inlet port in the top of the mixer and positioned so that particles fed there-through flow directly by gravity into the compartment defined by the first and second highest vertical partition walls, B. Discharging the entire contents of said first static mixer through its discharge port and feed-ing said discharged material into the inlet port of a second mixer; the volumetric capacity and construction of said mixer being substantially identical to that of said first mixer, and C. Discharging the entire contents of said second static mixer and recovering a batch of polymer particles of substantially uniform composition;
said process further characterized that the volumetric size of said batch of polymer particles is such that it completely fills each storage compartment of said static mixers.
A. Charging the entire batch of polymer particles to a first empty static mixer characterized in having;
(1) a prinicpal section of generally cylin-drical shape fitted with a conically shaped bottom section to provide ready gravity flow of particles from said mixer, (2) a centrally positioned discharge port in the bottom of the mixer, (3) a valve in said discharge port, (4) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall and divides the mixer into at least six storage compartments of sub-stantially equal volumetric capacity, said partition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the differences in height of the parti-tion walls are such that as each stor-age compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (c) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, (5) an inlet port in the top of the mixer and positioned so that particles fed there-through flow directly by gravity into the compartment defined by the first and second highest vertical partition walls, B. Discharging the entire contents of said first static mixer through its discharge port and feed-ing said discharged material into the inlet port of a second mixer; the volumetric capacity and construction of said mixer being substantially identical to that of said first mixer, and C. Discharging the entire contents of said second static mixer and recovering a batch of polymer particles of substantially uniform composition;
said process further characterized that the volumetric size of said batch of polymer particles is such that it completely fills each storage compartment of said static mixers.
12. A process of claim 10 in which the aliquot having the additive blended therewith is charged to the first mixer before the balance of said batch of polymer par-ticles is charged thereto.
13. A process for preparing a large batch of particulate polymers having a substantially uniform composition throughout which consists essentially of:
A. Filling in sequence a plurality of empty, hori-zontally aligned, essentially cylindrical mixers with particulate polymer, B. Simultaneously emptying each of the mixers of (A) at a uniform rate into a conveying means;
and C. Conveying the mixed particulate polymer product to a packaging station;
the process further characterized in that each mixer of (A) is essentially identical in volumetric capacity and construction and includes:
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to pro-vide ready gravity flow of particles from the mixer, (3) a centrally-positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the wall to divide the mixer into at least six storage compartments, said vertical par-tition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the angles formed between each adjacent pair of partition walls being substan-tially equal so that each storage com-partment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volu-metric rates from each compartment when the valve of the discharge port is opened, and (6) an inlet port in the top of the mixer posi-tioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest verti-cal partition walls.
A. Filling in sequence a plurality of empty, hori-zontally aligned, essentially cylindrical mixers with particulate polymer, B. Simultaneously emptying each of the mixers of (A) at a uniform rate into a conveying means;
and C. Conveying the mixed particulate polymer product to a packaging station;
the process further characterized in that each mixer of (A) is essentially identical in volumetric capacity and construction and includes:
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to pro-vide ready gravity flow of particles from the mixer, (3) a centrally-positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the wall to divide the mixer into at least six storage compartments, said vertical par-tition walls being further characterized in that;
(a) the partition walls are of spirally descending height, (b) the angles formed between each adjacent pair of partition walls being substan-tially equal so that each storage com-partment has substantially an equal volumetric capacity, (c) the differences in height of the parti-tion walls are such that as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volu-metric rates from each compartment when the valve of the discharge port is opened, and (6) an inlet port in the top of the mixer posi-tioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest verti-cal partition walls.
14. A first vertically aligned static mixer useful in blending flowable particles, said mixer being of essentially cylindrical shape and including:
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to provide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical partition walls being further characterized in that;
(a) the partition walls are of varying height with each wall other than the highest wall being higher than one adjacent wall and lower than the other adjacent wall, (b) the angles formed between each adjacent pair of partition walls being substantially equal so that each storage compartment has substantially an equal volumetic capacity, (c) the differences in height of the partition walls are such that as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, (6) an inlet port in the top of the mixer and positioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest vertical partition walls.
(1) a principal section that is essentially cylindrical in shape, (2) a bottom section of conical shape to provide ready gravity flow of particles from the mixer, (3) a centrally positioned discharge port in the bottom of the mixer, (4) a valve in said discharge port, (5) a series of at least six vertical partition walls within the mixer, each of which extends radially from the midpoint of the mixer to the mixer wall to divide the mixer into at least six storage compartments, said vertical partition walls being further characterized in that;
(a) the partition walls are of varying height with each wall other than the highest wall being higher than one adjacent wall and lower than the other adjacent wall, (b) the angles formed between each adjacent pair of partition walls being substantially equal so that each storage compartment has substantially an equal volumetic capacity, (c) the differences in height of the partition walls are such that as each storage compartment is filled with particles, additional particles added to the top of said compartment readily overflow into the adjacent compartment, and (d) the bottom of each partition wall extends to within inches of the discharge port, the bottom construction of the partition walls being such that particles flow by gravity at substantially equal volumetric rates from each compartment when the valve of the discharge port is opened, (6) an inlet port in the top of the mixer and positioned so that particles fed therethrough flow by gravity directly into the compartment defined by the first and second highest vertical partition walls.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23981581A | 1981-03-02 | 1981-03-02 | |
| US239,815 | 1981-03-02 | ||
| US250,988 | 1981-04-03 | ||
| US06/250,988 US4360044A (en) | 1981-04-03 | 1981-04-03 | Polymer mixing apparatus |
| US268,957 | 1981-06-01 | ||
| US06/268,957 US4385840A (en) | 1981-03-02 | 1981-06-01 | Mixing apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1170649A true CA1170649A (en) | 1984-07-10 |
Family
ID=27399280
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000397271A Expired CA1170649A (en) | 1981-03-02 | 1982-03-01 | Mixing apparatus |
Country Status (2)
| Country | Link |
|---|---|
| EP (1) | EP0060046A1 (en) |
| CA (1) | CA1170649A (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE8500193L (en) * | 1984-01-19 | 1985-07-20 | Recycloplast Ag | PROCEDURE FOR MIXING HELLABLE MATERIALS WITH AN ADJUSTABLE MIXING PROCEDURE AS A PART OF A PROCEDURE FOR PROCESSING THE MATERIAL AS A DEVICE FOR CARRYING OUT THE PROCEDURE |
| DE4112884C2 (en) * | 1991-04-19 | 1997-02-06 | Waeschle Maschf Gmbh | Mixing silo |
| DE4121649C1 (en) * | 1991-06-29 | 1992-08-13 | Plus Plan Gmbh, 6440 Bebra, De | |
| DE10332233B4 (en) * | 2003-07-16 | 2006-04-20 | Motan Materials Handling Gmbh | mixing silo |
| US7867042B2 (en) * | 2008-03-26 | 2011-01-11 | Tyco Electronics Corporation | Connector assembly with a low profile terminal position assurance member |
| PL2497565T3 (en) | 2011-03-11 | 2016-01-29 | Bayer Ip Gmbh | Mixing silo |
| KR101563088B1 (en) * | 2014-07-14 | 2015-10-26 | 주식회사 엔케이 | Apparatus for storage and dissolution of chemical agent for sterilization of ballast water |
| CN105857967B (en) * | 2016-05-16 | 2019-07-23 | 平原县三兴饲料厂 | A kind of anti-fractionated container and anti-classification feed bin and anti-classification vehicle-mounted bulk cargo tank |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1240376B (en) * | 1964-04-30 | 1967-05-11 | Peters Ag Claudius | Method and device for mixing a continuous material flow of a pourable material |
| US3414164A (en) * | 1967-03-06 | 1968-12-03 | Electric Reduction Co | Blending apparatus for solids |
| US3814386A (en) * | 1968-11-13 | 1974-06-04 | Plastic Materials Syst Inc | Method for vibratory blending of fluid particulate materials |
| FR2225460A1 (en) * | 1973-04-12 | 1974-11-08 | Aquitaine Total Organico | Vinyl chloride polymer powder compsns - contg liquid and solid additives and prepd without heating |
| NL7611090A (en) * | 1975-10-09 | 1977-04-13 | Ici Ltd | METHOD AND DEVICE FOR MIXING. |
| US4025480A (en) * | 1975-11-19 | 1977-05-24 | Phillips Petroleum Company | Dry blending system for polyethylene fluff and additives |
-
1982
- 1982-02-22 EP EP82300882A patent/EP0060046A1/en not_active Withdrawn
- 1982-03-01 CA CA000397271A patent/CA1170649A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| EP0060046A1 (en) | 1982-09-15 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |