WO1996034240A1 - Procede et dispositif de rechauffement et/ou de sechage par un champ moyenne frequence de materiaux en poudre, en granules ou en pate dans un reservoir de melange conique - Google Patents

Procede et dispositif de rechauffement et/ou de sechage par un champ moyenne frequence de materiaux en poudre, en granules ou en pate dans un reservoir de melange conique Download PDF

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Publication number
WO1996034240A1
WO1996034240A1 PCT/NL1996/000186 NL9600186W WO9634240A1 WO 1996034240 A1 WO1996034240 A1 WO 1996034240A1 NL 9600186 W NL9600186 W NL 9600186W WO 9634240 A1 WO9634240 A1 WO 9634240A1
Authority
WO
WIPO (PCT)
Prior art keywords
mhf
vessel
mixing
mixing vessel
antennae
Prior art date
Application number
PCT/NL1996/000186
Other languages
English (en)
Inventor
Antonius Maria Van Aken
Original Assignee
Hosokawa Micron B.V.
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Hosokawa Micron B.V. filed Critical Hosokawa Micron B.V.
Priority to JP8532396A priority Critical patent/JPH11504702A/ja
Publication of WO1996034240A1 publication Critical patent/WO1996034240A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B5/00—Drying solid materials or objects by processes not involving the application of heat
    • F26B5/04—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum
    • F26B5/048—Drying solid materials or objects by processes not involving the application of heat by evaporation or sublimation of moisture under reduced pressure, e.g. in a vacuum in combination with heat developed by electro-magnetic means, e.g. microwave energy
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B11/00—Machines or apparatus for drying solid materials or objects with movement which is non-progressive
    • F26B11/12—Machines or apparatus for drying solid materials or objects with movement which is non-progressive in stationary drums or other mainly-closed receptacles with moving stirring devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F26—DRYING
    • F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
    • F26B3/00—Drying solid materials or objects by processes involving the application of heat
    • F26B3/32—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action
    • F26B3/34—Drying solid materials or objects by processes involving the application of heat by development of heat within the materials or objects to be dried, e.g. by fermentation or other microbiological action by using electrical effects
    • F26B3/347—Electromagnetic heating, e.g. induction heating or heating using microwave energy

Definitions

  • the invention relates to a method for heating and/or drying of powdery, grainy and/or pasty materials in a conical mixing vessel having a vertical axis, which narrows in a downward direction and in which the material is mixed by at least one mixing screw, which makes a rotating movement around its axis and a revolving movement parallel to the innerside of the vessel wall, whereas the material to be heated and/or dried is irradiated by at least a HF-field.
  • a method of this type is known from EP 0 306 563.
  • one or more microwave generators or magnetrons are present on top of the lid of the conical mixing vessel.
  • the antennae of these microwave generators extend into the vessel, but stay out of contact with the material to be dried.
  • These antennae radiate from the lid of the vessel a UHF-field with a frequency of 900- 2450 MHz or more to the free upper surface of the material to be dried, which is held into movement by one or more mixing screws.
  • the microwave radiation heats and evaporates the solvent which is present in the material, so that a quick drying is obtained.
  • the object of the invention is adapting this known method in such a way, that it is made suitable for drying of materials, which are very sensitive for microwave radiation and could easily change their characteristics in a undesirable way.
  • this object is attained, by radiating a MHF- or RF-field substantially completely inside the material (M) to be heated and/or dried.
  • Such a MHF- or RF-field has a frequency of 3-150 MHz.
  • the intersecting jn 6/34240 the intersecting jn 6/34240
  • MHF-field has a frequency of 10 through 50 MHz, preferentially 27 MHz.
  • the absorption of energy for drying is the result of the product of the dielectric constant of the material to be dried and the dielectric constant of the material to be heated and/or dried and the dissipation factor.
  • This product is the loss factor and if it is greater than 0,05, the material can be heated dielectrically, such as for instance water and many alcohols.
  • This MHF- or RF-field does not cause any damage of materials which are sensible for UHF radiation and allows the efficient heating and/or drying of the material. By the quick changes of the polarities heat is generated in the material to be heated and/or dried.
  • the MHF- or RF-field is rotated around a vertical symmetry axis of the vessel with the same rotation velocity as the revolving velocity, which is connected with one or more electrically conductive antennae mounted inside the mixing vessel, which antennae are intended to extend substantially complete inside the material to be dried, whereas the conductors outside the mixing vessel are connected to the HF-generator. In this way a very good heating and/or drying of the material is attained.
  • Fig. 1 shows a vertical sideview of the drier according to the invention.
  • Fig. 2 shows the drier of fig. 1 together with the electrical and the vacuum circuit.
  • Fig. 3A and 3B show in cross-section and sideview a conical antenna with two symmetrical sectors.
  • Fig. 4 shows the electrical circuit of the impedance adaptor.
  • Fig. 1 shows a heated mixer/drier according to the invention which is generally indicated with 1. It comprises a steel conical mixing vessel 2 having a vertical symmetry axis, and a mixing screw 3, which at the one hand rotates around its own axis and at the other hand revolves parallel to the sidewall of the vessel 2.
  • the electrical motordrive 6 mounted on top of the concave lid 8 of the vessel is for driving the mixing screw 3 and thus for mixing of the material M to be dried. Vacuum is drawn on the mixing vessel 2 at the tube stub 9.
  • the material M to be treated is supplied to the right tube stub on the mixing vessel having a releasable and mountable lid 8.
  • an isolated coaxial cylindrical electrical conductor 5 has been mounted in the central symmetry axis of the mixing vessel 2, which conductor has been connected inside the mixing vessel with an electrical conductive cylindrical HF antenna 4.
  • the antenna 4 has been connected to a MHF- or RF-source outside the vessel 2.
  • Such a MHF- or RF-source has generally a frequency of 3-150 MHz. In this embodiment the frequency amounts to 10 through 50 MHz, preferably 27 MHz.
  • the antenna 4 and the mixing vessel 2 form the metal plates of a capacitor between which the MHF- or RF-field caused by the MHF- or RF-source 11 is present. This causes the desired heating and/or drying of the material M which is held into movement by the mixing vessel 3, so that the treatment happens homogeneously and there is no local overheating.
  • Fig. 2 shows the antenna 4 in the vessel 2.
  • the MHF-source 11 is at one hand connected to the antenna 4 through an impedance adaptor 10 and at the other hand to the vessel 2.
  • the impedance adaptor 10 serves to adjust the impedance according to the further heating and/or drying of the material M.
  • fig. 2 shows a vacuum controller 16, which serves to control the level of the vacuum in the mixing vessel together with a computer PC.
  • the mixing screw 3 is constantly in the HF field.
  • this mixing screw is as usually from metal, a HF voltage will occur, which may raise until 6.000 Volt.
  • the MHF- or RF-field is strong and the mixing screw 3 is closed with a wall of the mixing vessel 2, there is danger for producing sparks from the outer edge of the helical edge along the mixing screw 3 to the vessel wall 2.
  • This can be counteracted by making the mixing screw 3 from an isolating material, such as plastic or ceramics, or provide a metal mixing screw with a cover of plastic, ceramics or another isolated cover.
  • Suitable ceramic materials are formed by aluminiumoxyde, porcelain, steatyte, and titaniumdioxyde.
  • Suitable plastics are formed by polytetrafluortereftelate (TEFLON, trademark of DuPont), polyethylene or polypropylene.
  • the innertube 12 extends through the isolation 13 to the antenna 4A and the outertube 14 to the antenna 4B. A and B are connected to the vessel 2 and the antenna 4 respectively.
  • the outside of the outertube 14 is provided with isolation 15.
  • the antenna 12, 14 is also provided with isolation 13 between the innertube 12 and the outertube
  • This isolation 13 extends somewhat further with regard to said outer isolation 15, to prevent sparking, especially in connection with the HF-tension which can reach values until 6.000 Volt.
  • the sleeve 16 is mounted around the coaxial conductors 12, 14. This sleeve 16 is connected at the upperside with the outer tube 14 of the coaxial conductor 12, 14. At the lower side, close to the antenna connection A, B this sleeve has not been connected. When this outer sleeve 16 is brought into resonance at the frequency of the generator, then the impedance between this sleeve 16 and the outer tube 14 of the coaxial conductor 12, 14 will become infinitively high. This gives a substantially ideal balancing of the antenna device. Bringing the sleeve 16 into resonance can be achieved by giving it a length of a quarter wave length. The same cross-section as in fig. 3A is visible in fig. 4A.
  • the outer sleeve 16 has a length L, which should be electrically a quarter wave length.
  • a lower part of the isolation material 15 can be replaced by ceramic material, such as aluminiumoxyde, porcelain, steatite or titaniumoxyde, with still higher Er values.
  • a possible fine adjustment of the sleeve 16 can be realised very well by using a dielectric material having a high dielectic constant in the shape of the tube 15 between the sleeves 16 and the outer tube 14 of the coaxial conductor 12, 14.
  • the position of the dielectric tube influences the setting frequency of the sleeve.
  • This antenna device 4A, 4B has as object to reduce to a minimum the tension of the mixing screw.
  • the antenna 4 therefore comprises a system of two antennae 4A, 4B which are symmetrically ranged with respect to the mixing screw 3.
  • the tension on the two antennae 4A, 4B is equal, but in counterphase. Therefore no tension will build up on the mixing device and there is also no bearing current.
  • the surpression of the bearing current with respect to a non- symmetrical antenna device will amount to more than a factor 10, which results in a maximum supplied power of more than a hundred times in comparison with the non- balanced antenna.
  • the disadvantages of the central antenna have therefore disappeared.
  • a possible embodiment of such an antenna device is shown in fig. 2.
  • the antenna 4A, 4B comprises two conical segments which are connected to the coaxial conductors 12 and 14. Furthermore in fig. 3A an embodiment is visible of a construction of the lead through of the outer tube 4 and the inner tube 12, with inner isolation 13 and outer isolation 15.
  • the antennae 4A, B can have the shape of a cone or of hollow cone sectors.
  • the cone angle in fig. 3A, B equals the cone angle of the mixing vessel 2.
  • the antenna 4 is rotary driven, for instance my means of a horizontal arm, on which the upper end of the mixing screw 3 is fastened. In this way at least one mixing screw 3 can be used between the antenna sectors 17.
  • the impedance of the antenna is unknown. Furthermore the characteristics of the material will change and therefore also the impedance, during the proceeding of the drying process. This alteration of the impedance can cover an important interval.
  • This antenna tuner transforms the variable antenna impedance to a real value of 50 Ohm.
  • the antenna tuner or impedance adaptor comprises a circuit of a first variable capacitor 18, connected to the antenna line 17, a spool 19 and a second variable capacitor 20.
  • the complete tuning procedure can be done by hand. It is also possible to have it done automatically.
  • the impedance adaptor comprises a second circuit with a sensor circuit 21, which turns the first variable capacitor 18 of the first circuit by means of a control amplifier 22 and a motor 23. Also a second sensor circuit 24 is present, which controls a second motor 26 through a second control amplifier 25, whereas the motor 26 turns the second variable capacitor 20 of the first circuit 17, 18.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Microbiology (AREA)
  • Molecular Biology (AREA)
  • Electromagnetism (AREA)
  • Biomedical Technology (AREA)
  • Biotechnology (AREA)
  • Physics & Mathematics (AREA)
  • Drying Of Solid Materials (AREA)
  • Constitution Of High-Frequency Heating (AREA)

Abstract

Procédé et dispositif de réchauffement et/ou de séchage de matériaux en poudre, en granulés ou en pâte par un champ moyenne fréquence dans un réservoir de mélange conique (2) possédant un axe vertical, se rétrécissant dans le sens descendant et dans lequel le matériau est mélangé par au moins une vis de mélange (3) effectuant une rotation autour de son axe et une révolution parallèle au côté intérieur du réservoir de mélange (1), tandis que le matériau à réchauffer et/ou à sécher est irradié par au moins un champ haute fréquence. L'invention est caractérisée par le fait que le champ moyenne fréquence ou haute fréquence pénètre pratiquement totalement à l'intérieur du matériau à réchauffer et/ou à sécher, ce champ possédant une fréquence de 10 à 50 Mhz, de préférence 27 Mhz, et effectue une rotation autour de l'axe vertical du réservoir (2) à la même vitesse que la vitesse de rotation de la vis de mélange (3). L'impédance de l'antenne (4) pour le champ moyenne fréquence est, de préférence, adaptée à la variation de l'impédance du matériau à réchauffer et/ou à sécher.
PCT/NL1996/000186 1995-04-28 1996-04-27 Procede et dispositif de rechauffement et/ou de sechage par un champ moyenne frequence de materiaux en poudre, en granules ou en pate dans un reservoir de melange conique WO1996034240A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP8532396A JPH11504702A (ja) 1995-04-28 1996-04-27 粉状、粒状及び／又はペースト状の物質を円錐形の混合容器内でｍｈｆの場によって加熱及び／又は乾燥するための方法及び装置

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL1000248 1995-04-28
NL1000248A NL1000248C2 (nl) 1995-04-28 1995-04-28 Werkwijze en inrichting voor met een MHF-veld verwarmen en/of drogen van poeder-, korrelvormige en/of pasteuze materialen in een conisch mengvat met tenminste een roterende en wentelende mengschroef.

Publications (1)

Publication Number Publication Date
WO1996034240A1 true WO1996034240A1 (fr) 1996-10-31

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PCT/NL1996/000186 WO1996034240A1 (fr) 1995-04-28 1996-04-27 Procede et dispositif de rechauffement et/ou de sechage par un champ moyenne frequence de materiaux en poudre, en granules ou en pate dans un reservoir de melange conique

Country Status (3)

Country Link
JP (1) JPH11504702A (fr)
NL (1) NL1000248C2 (fr)
WO (1) WO1996034240A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014160721A1 (fr) * 2013-03-25 2014-10-02 Dry Grain LLC Séchage radiofréquence de matériau collecté
DE102016114551A1 (de) * 2016-08-05 2018-02-08 Teka Maschinenbau Gmbh Mischvorrichtung mit unabängig voneinander steuerbaren Mischschaufeln
DE102016114557A1 (de) * 2016-08-05 2018-02-08 Teka Maschinenbau Gmbh Mischtrog für eine Mischeinrichtung
CN112992428A (zh) * 2021-03-05 2021-06-18 乐福之家纳米材料有限责任公司 一种用于石墨烯导电浆料或粒子的生产设备

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110425846A (zh) * 2019-07-09 2019-11-08 江苏中海华核环保有限公司 一种用于处理带有放射性的废树脂的锥形干燥器

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB593806A (en) * 1944-01-31 1947-10-27 Rca Corp Improvements in the dehydration of fluid materials by high frequency electric fields
DE899924C (de) * 1944-09-09 1953-12-17 Siemens Ag Vorrichtung zur Behandlung von Schuettgut im elektrischen oder magnetischen, insbesondere hochfrequenten Wechselfeld
FR1324833A (fr) * 1962-06-13 1963-04-19 Leybold Hochvakuum Anlagen Procédé de séchage ou de dégazage sous vide de matières en poudre
US3432636A (en) * 1965-03-09 1969-03-11 Pet Inc Method of and apparatus for producing dry concentrates from liquid materials
EP0005552A2 (fr) * 1978-05-23 1979-11-28 Bruno Granella Dispositif de chauffage et de mélange de matériaux de construction
EP0093474A2 (fr) * 1982-04-29 1983-11-09 Clini-Therm Acquisition Corp. Procédé et dispositif pour transporter et traiter par radiofréquence des matériaux diélectriques
GB2158365A (en) * 1985-05-09 1985-11-13 Littleford Bros Inc Combined mixing, reacting, drying and filtering device
EP0306563A1 (fr) * 1987-09-10 1989-03-15 Hosokawa Micron Europe B.V. Appareil de séchage de matière mélangée avec un dissolvant

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB593806A (en) * 1944-01-31 1947-10-27 Rca Corp Improvements in the dehydration of fluid materials by high frequency electric fields
DE899924C (de) * 1944-09-09 1953-12-17 Siemens Ag Vorrichtung zur Behandlung von Schuettgut im elektrischen oder magnetischen, insbesondere hochfrequenten Wechselfeld
FR1324833A (fr) * 1962-06-13 1963-04-19 Leybold Hochvakuum Anlagen Procédé de séchage ou de dégazage sous vide de matières en poudre
US3432636A (en) * 1965-03-09 1969-03-11 Pet Inc Method of and apparatus for producing dry concentrates from liquid materials
EP0005552A2 (fr) * 1978-05-23 1979-11-28 Bruno Granella Dispositif de chauffage et de mélange de matériaux de construction
EP0093474A2 (fr) * 1982-04-29 1983-11-09 Clini-Therm Acquisition Corp. Procédé et dispositif pour transporter et traiter par radiofréquence des matériaux diélectriques
GB2158365A (en) * 1985-05-09 1985-11-13 Littleford Bros Inc Combined mixing, reacting, drying and filtering device
EP0306563A1 (fr) * 1987-09-10 1989-03-15 Hosokawa Micron Europe B.V. Appareil de séchage de matière mélangée avec un dissolvant

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014160721A1 (fr) * 2013-03-25 2014-10-02 Dry Grain LLC Séchage radiofréquence de matériau collecté
US9303919B2 (en) 2013-03-25 2016-04-05 Dry Grain LLC Radio frequency drying of harvested material
US10006702B2 (en) 2013-03-25 2018-06-26 Dry Grain LLC Radio frequency drying of harvested material
DE102016114551A1 (de) * 2016-08-05 2018-02-08 Teka Maschinenbau Gmbh Mischvorrichtung mit unabängig voneinander steuerbaren Mischschaufeln
DE102016114557A1 (de) * 2016-08-05 2018-02-08 Teka Maschinenbau Gmbh Mischtrog für eine Mischeinrichtung
CN112992428A (zh) * 2021-03-05 2021-06-18 乐福之家纳米材料有限责任公司 一种用于石墨烯导电浆料或粒子的生产设备

Also Published As

Publication number Publication date
JPH11504702A (ja) 1999-04-27
NL1000248C2 (nl) 1996-10-29

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