US3756569A - Apparatus for mixing and homogenising bulk material and method of operating the apparatus - Google Patents

Apparatus for mixing and homogenising bulk material and method of operating the apparatus Download PDF

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Publication number
US3756569A
US3756569A US00155362A US3756569DA US3756569A US 3756569 A US3756569 A US 3756569A US 00155362 A US00155362 A US 00155362A US 3756569D A US3756569D A US 3756569DA US 3756569 A US3756569 A US 3756569A
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United States
Prior art keywords
riser
container
gas
mixing
materials
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Expired - Lifetime
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US00155362A
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English (en)
Inventor
A Wohlfarth
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Bayer AG
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Bayer AG
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Publication date
Priority claimed from DE19691937374 external-priority patent/DE1937374C/de
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    • 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
    • B01F33/40—Mixers using gas or liquid agitation, e.g. with air supply tubes
    • B01F33/405—Mixers using gas or liquid agitation, e.g. with air supply tubes in receptacles having guiding conduits therein, e.g. for feeding the gas to the bottom of the receptacle
    • B01F33/4051—Mixers using gas or liquid agitation, e.g. with air supply tubes in receptacles having guiding conduits therein, e.g. for feeding the gas to the bottom of the receptacle with vertical conduits through which the material is being moved upwardly driven by the fluid
    • B01F33/40511—Mixers using gas or liquid agitation, e.g. with air supply tubes in receptacles having guiding conduits therein, e.g. for feeding the gas to the bottom of the receptacle with vertical conduits through which the material is being moved upwardly driven by the fluid with a central conduit or a central set of conduits

Definitions

  • a container with a conical base for the pneumatic mixing of material in powder or granulated form, and with a gas supply means at the bottom has at least one riser pipe arranged therein, said pipe ends in the upper region of the container and is formed with openings or gaps. At least one opening or gap is formed as an annular passage, which divides the riser pipe into a lower section and an upper section. The upper end of the lower section surrounds and is spaced from the lower end of the upper section, whereby said gap is defined.
  • the invention relates to a container having a conical base for pneumatically mixing material in powder or granulated form, said container having at the bottom outlet a gas supply means and having at least one riser pipe arranged therein, said pipe terminating in the upper region of the container and having openings or gaps.
  • the invention is further concerned with two different methods of operating the mixing container, by means of which the material is propelled into the riser pipe by gas introduced at the base.
  • the riser pipe arranged in the mixing container is concentrically enclosed by a second perforated pipe of larger diameter, the lower end of this pipe being-closed by an annular cover.
  • the powder or granulated material in this case penetrates through the openings in the casing of the perforated pipe into the annular chamber between the two pipes, falls due to gravitational force and is carried upwardly with other material from the bottom of the mixing container by means of a compressed gas stream through the riser pipe.
  • the invention has for an object to provide a simple mixer which can be easily cleaned and which does not have any complicated fittings, with which a good longitudinal mixing and a good transverse mixing and therefore a short mixing time is ensured.
  • a simple riser pipe without complicated air or product supply means is provided. Furthermore, low gas velocities are required in the mixing pipe and at the feeding position, so that the abrasion of the product remains small.
  • At least one opening or gap formed as an annular passage is provided on the riser pipe in the mixing container, the said gap dividing the riser pipe into the lower section and an upper section, the upper end of the lower section being widened and surrounding the lower end of the upper section while leaving an annular gap.
  • the mixing gas is supplied to the container at the bot-' tom end of the mixer housing.
  • Air is advantageously used as mixing gas.
  • the conical bottom of the mixer housing which terminates in a cylindrical end member, is for this purpose provided with an air supply chamber enclosing the cylindrical end section in annular fonn, said chamber also having a conical bottom.
  • the conical bottom of the air supply chamber in this case serves simultaneously as the outlet for the product.
  • A- good mixing action of the apparatus as described is only assured if the gas stream provided for the mixing actually only flows through the riser pipe provided for it.
  • a particularly good longitudinal mixing is obtained when the riser pipe is arranged eccentrically in the container.
  • the gas selects its path through the riser pipe and through the mixing container in an upward vertical direction.
  • the container is filled to a selected level between the bottom and top of the riser.
  • the level of product in the annular chamber between the inside wall of the container and the riser pipe is higher than in the latter.
  • the mixing gas now flows for the major part through the riser pipe, because there it has to overcome a smaller flow resistance because of the lower product level.
  • annular passages are to be easily cleaned after the mixing process and that no deposits of product occur therein.
  • the product to be mixed is disposed in the mixing container and in the riser pipe up to at least the height of the upper end of the annular chamber in densely packed form.
  • the mixing gas supplied at the bottom of the mixer has to force the plug of product beneath the bottom end of the riser pipe into the said pipe. In this case, very large shearing stresses have to be overcome at the periphery of the initially still consolidated plug of product.
  • the plug is also loaded by the weight of the product column in the riser pipe.
  • the pressure necessary for starting up the mixer is usually a multiple of the pressure required for the continued mixing.
  • the annular passages can for example change in crosssection or be completely closed by inflatable, elastic closure elements arranged therein or by sections of the riser pipe being arranged to be relatively adjusted in height.
  • the product to be mixed can be introduced into the mixing container with the annular passages of the riser pipe closed.
  • the result hereby obtained is that the introduced product can only penetrate from the bottom of the mixing container into the riser pipe, so that the level of product in said pipe only reaches a very small height.
  • the plug of product between the bottom end of the riser pipe and the bottom of the container now has only to be moved upwardly against the shearing stresses at its periphery with supply of the mixing gas, since the weight of the column of product in the riser pipe by which it is additionally loaded is avoided.
  • the pressure on starting the lastmentioned mixer can be reduced from 20 111 water column to about 2.0 m water column.
  • the annular passages in the riser pipe are also opened again.
  • At least one additional gas supply pipe is provided, which opens into the conical mixer bottom at or near the height of the inlet end of the riser pipe.
  • the mixing gas can now initially be introduced into the mixing container from the gas supply pipe at the higher position.
  • the product in the riser pipe is loosened.
  • the gas supply at the bottom of the conical mixing container is gradually opened and the upper gas supply is continuously closed to the same extent. It is still only necessary to loosen the plug of product beneath the riser pipe by the mixing gas which is now flowing in from the bottom of the container. Due to the initially relatively long plug of product inside and outside the riser pipe being loosened in stages, a reduction of the starting pressure is to be obtained, in a similar manner as when closing the annular passages in the riser pipe at the start of the mixing operation.
  • a filling level is maintained in the container according to the invention above the level of the upper end of the annular passage such that the pressure of the material in the bed in the container exceeds the mixing gas pressure in the region of the annular passage and material enters by way of the annular passage into the riser pipe is mixed with the material introduced at the bottom end of the riser pipe.
  • This method can always be carried out when, after the introduction of the product to the mixing container, the level of product outside the riser pipe is higher than the upper opening of the annular passage.
  • the gas introduced at the bottom outlet initially lifts, as before, the material into the riser pipe.
  • a part of the gas transported into the riser pipe is caused to overflow through the annular passage, while periodically another part of the material is lifted into the upper section of I closing the outlet, for withdrawal of mixed materials.
  • the vertically extending riser is disposed in the container above and spaced from the outlet opening, and the riser comprises an upper section and a lower section.
  • the two sections are in overlapping, radially spaced relation, defining an annular passage therebetween.
  • the upper section terminates above the lower section and the lower section has its lower end at least as low as the lower end of the upper section.
  • Means are provided for supplying gas for the mixing, to the container below the lower end of the riser for passage of the gas into the container and pneumatic lifting and mixing of the gas and materials in the riser with the materials filling the container to above the lower end of the riser.
  • the means for supplying gas for the mixing comprises two vertically spaced gas inlet conduits outfitted with valve means for selectively apportioning the flow of gas between the two conduits.
  • a baffle can be disposed above and spaced from the upper end of the riser for intercepting the mixture of gas and particles issuing from the riser, and separating the particles from the gas.
  • a gas outlet can be disposed above the baffle for discharge of the gas from the container after the separation by the baffle.
  • the lower section diverges upwardly. Further, in a preferred embodiment, the lower end of the lower section of the riser, terminates below the lower end of the upper section thereof. Also, as mentioned previously, means can be provided for adjusting the flow area of the annular'passage, and, desirably, for selectively closing the annular passage.
  • FIG. 1 is a section through the complete mising apparatus
  • FIG. 2 is a section through one embodiment of the riser pipe.
  • the mixer which is illustrated in FIG. 1 consists of a cylindrical container 1 having a conical bottom 2 and a removable cover 3.
  • a riser pipe which consists of a conical lower section 4, which diverges upwardly, and a cylindrical upper section 5, is fixed by stay members 7 a and 7b in the container 1.
  • the two sections of the riser pipe are fitted one within the other, leaving an annular passage 6.
  • the upper section 5 is provided with spacer plates 9 welded radially thereon.
  • a gas supply chamber 11 Flanged on the conical mixer bottom 2, which terminates in a cylindrical end section 10, is a gas supply chamber 11, said chamber having a conical bottom 12 which serves simultaneously as the outlet for the product and on which is arranged a bucket wheel lock chamber or star valve 13 serving as closure member.
  • the mixing gas delivered by a compressor may at will be supplied to the mixing container through pipe conduit 14 by way of the gas supply chamber 11 or through the pipe conduit 15 by way of an opening in the conical mixer bottom 2 and covered by a screen l6.
  • the pipe conduits and 15 can both be closed by means of shut-off valves 17.
  • baffle or shielding cone 20 Fixed on the radial guide plates 18 in the exhaust gas pipe 19 of the cover 3 of the mixer is the baffle or shielding cone 20 with the rod 21.
  • the mixing container is filled through a feed pipe 22 opening tangentially into the container, said pipe 22 being subsequently closed by the flap valve 23.
  • the mixing gas is initially supplied through the pipe 15.
  • the pipe 14 is closed by the flap valve 17. Since the level of the product in the mixing container 1 after the container has been filled is higher than the level in the riser pipe, the gas chooses the path of lower resistance through the riser pipe and loosens the product which is disposed therein.
  • the pipe 14 can now be opened and the pipe 15 can be closed to the same degree.
  • the mixing gas now enters through the gas supply chamber 11 and through the cylindrical end member 10 of the conical mixer bottom 2 into the riser pipe 4 and 5 and thus carries in a vertically upward direction through the riser pipe the product which is disposed beneath the lower riser pipe section 4.
  • the product is then centrifuged radially outwards from the riser pipe.
  • the mixing gas is discharged through the pipe 19.
  • other product slips downwardly from the annular chamber between the riser pipe and the mixer wall 1.
  • Some of the bulk material descends through the annular passage 6 into the riser pipe and is homogenised therein with the product coming from the bottom of the mixer.
  • the mixing process as described here can however only be carried into effect when the level of the product in the mixing container is higher than the upper end of the lower section 4 of the riser pipe.
  • the lower end of the riser lower section is located about 0.4 meters above the outlet 10, and about 0.2 meters above the inlet 16 of conduit 15.
  • the riser lower section is 440 cm in length, 50 cm in diameter at its lower end and 80 cm in diameter at its upper end.
  • the riser upper section is 550 cm in length and 50 cm in diameter.
  • the over lap of the riser section is 300 cm.
  • the mixer can be filled to about the level indicated in the drawing with polyester granulate of particle size of 3 mm and glass fibers of 0.3 mm diameter and a length of about 5 mm, in the weight proportion of 80 20.
  • the pressure necessary for starting is 1000 mm of water; after start up, using conduit 14, the running pressure is also about 2000 mm of water.
  • Thorough mixing of the batch is completed in about 60 minutes.
  • Star valve 13 can be operated to empty the container. In batch operation, the first runnings discharged by the star valve will not be well mixed and can be saved for use in a later mixing operation.
  • the equipment can be operated continuously.
  • Apparatus suitable for pneumatically mixing materials in finely divided form comprising:
  • a vertically extending container having an inlet opening adjacent its upper end for introduction of finely divided materials, and an outlet means in the lower end outfitted with means for selectively closing the outlet, for withdrawal of mixed materials
  • a vertically extending riser disposed in the container above and spaced from the outlet opening and comprising an upper section and a lower section, said sections being in overlapping, radially spaced relation defining an annular passage therebetween, with the upper section terminating above the lower section and the lower section having its lower end at least as low as the lower end of the upper section,
  • said means for supplying gas for said mixing comprising two vertically spaced gas inlet conduits and valve means for selectively apportioning the flow of gas between the two conduits.
  • Apparatus according to claim 1 and a baffle disposed above and spaced from the upper end of the riser for intercepting the mixture of gas and particles and separating the particles from the gas.
  • Process of pneumatically mixing materials in finely divided form with apparatus comprising:
  • a vertically extending container having an inlet opening adjacent its upper end for introduction of finely divided materials, and an outlet means in the lower end outfitted with means for selec-tively closing the outlet, for withdrawal of mixed materials
  • a vertically extending riser disposed in the container above and spaced from the outlet opening and comprising an upper section and a lower section, said sections being in overlapping, radially spaced relation defining an annular passage therebetween, with the upper sectionterminating above the lower section and the lower section having its lower end at least as low as the lower end of the upper section,
  • said level of the finely divided material being such that finely divided material during the process flows downwardly through said annular passageway and into the mixture of gas and finely divided material rising through the riser, and
  • a vertically extending container having an inlet opening adjacent its upper end for introduction of finely divided materials, and an outlet means in the lower end outfitted with means for selectively closing the outlet, for withdrawal of mixed materials
  • a vertically extending riser disposed in the container above and spaced from the outlet opening and comprising an upper section and a lower section, said sections being in overlapping, radially spaced relation defining an annular passage therebetween, with the upper section terminating above the lower section and the lower section having its lower end at least as low as the lower end of the upper section,

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Accessories For Mixers (AREA)
  • Mixers With Rotating Receptacles And Mixers With Vibration Mechanisms (AREA)
US00155362A 1969-07-23 1971-06-21 Apparatus for mixing and homogenising bulk material and method of operating the apparatus Expired - Lifetime US3756569A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691937374 DE1937374C (de) 1969-07-23 Behälter zum pneumatischen Mischen von pulvrigem oder körnigem Gut

Publications (1)

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US3756569A true US3756569A (en) 1973-09-04

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US00155362A Expired - Lifetime US3756569A (en) 1969-07-23 1971-06-21 Apparatus for mixing and homogenising bulk material and method of operating the apparatus

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US (1) US3756569A (de)
CH (1) CH516337A (de)
FR (1) FR2055558A5 (de)
GB (1) GB1244300A (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3953003A (en) * 1974-06-06 1976-04-27 Aluterv Aluminiumipari Tervezo Vallalat Tank provided with pneumatic mixing pipe
US3973757A (en) * 1974-04-10 1976-08-10 Polysius Ag Silo for mixing and homogenizing bulk material
US4097927A (en) * 1975-08-02 1978-06-27 Chimkombinat Apparatus for mixing bulk materials
US4978227A (en) * 1986-04-03 1990-12-18 Fuller Company Blender for solid particulate material
WO1992003221A1 (en) * 1990-08-24 1992-03-05 Fuller Company Apparatus for blending particulate material
US20070193649A1 (en) * 2006-02-17 2007-08-23 Podd Stephen D Pressure differential manlid and method of discharging a shipping container using a pressure differential
CN103211301A (zh) * 2013-04-27 2013-07-24 红云红河烟草(集团)有限责任公司 一种流化床式烟梗颗粒喂料装置及其喂料方法

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3807705A (en) * 1972-06-28 1974-04-30 Du Pont Process and apparatus for solids blending
GB2238712B (en) * 1989-12-11 1993-11-03 Kenwood Marks Ltd Food processor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3179378A (en) * 1962-12-26 1965-04-20 Ducon Co Apparatus for mixing and transporting finely divided solids
US3276753A (en) * 1964-08-17 1966-10-04 Fuller Co Apparatus for lifting and blending loose solids
US3490655A (en) * 1966-08-17 1970-01-20 Colgate Palmolive Co Material blending silo
US3647188A (en) * 1970-03-25 1972-03-07 Fuller Co Airlift blending apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3179378A (en) * 1962-12-26 1965-04-20 Ducon Co Apparatus for mixing and transporting finely divided solids
US3276753A (en) * 1964-08-17 1966-10-04 Fuller Co Apparatus for lifting and blending loose solids
US3490655A (en) * 1966-08-17 1970-01-20 Colgate Palmolive Co Material blending silo
US3647188A (en) * 1970-03-25 1972-03-07 Fuller Co Airlift blending apparatus

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3973757A (en) * 1974-04-10 1976-08-10 Polysius Ag Silo for mixing and homogenizing bulk material
US3953003A (en) * 1974-06-06 1976-04-27 Aluterv Aluminiumipari Tervezo Vallalat Tank provided with pneumatic mixing pipe
US4097927A (en) * 1975-08-02 1978-06-27 Chimkombinat Apparatus for mixing bulk materials
US4978227A (en) * 1986-04-03 1990-12-18 Fuller Company Blender for solid particulate material
WO1992003221A1 (en) * 1990-08-24 1992-03-05 Fuller Company Apparatus for blending particulate material
US20070193649A1 (en) * 2006-02-17 2007-08-23 Podd Stephen D Pressure differential manlid and method of discharging a shipping container using a pressure differential
CN103211301A (zh) * 2013-04-27 2013-07-24 红云红河烟草(集团)有限责任公司 一种流化床式烟梗颗粒喂料装置及其喂料方法

Also Published As

Publication number Publication date
CH516337A (de) 1971-12-15
DE1937374A1 (de) 1971-02-04
GB1244300A (en) 1971-08-25
FR2055558A5 (de) 1971-05-07

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