CA1234877A - Apparatus for heating granular materials - Google Patents
Apparatus for heating granular materialsInfo
- Publication number
- CA1234877A CA1234877A CA000479178A CA479178A CA1234877A CA 1234877 A CA1234877 A CA 1234877A CA 000479178 A CA000479178 A CA 000479178A CA 479178 A CA479178 A CA 479178A CA 1234877 A CA1234877 A CA 1234877A
- Authority
- CA
- Canada
- Prior art keywords
- heating chamber
- tubular portion
- granular material
- heating
- microwave energy
- 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
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/78—Arrangements for continuous movement of material
- H05B6/784—Arrangements for continuous movement of material wherein the material is moved using a tubular transport line, e.g. screw transport systems
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/78—Arrangements for continuous movement of material
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Apparatuses For Bulk Treatment Of Fruits And Vegetables And Apparatuses For Preparing Feeds (AREA)
- Constitution Of High-Frequency Heating (AREA)
Abstract
APPARATUS FOR HEATING GRANULAR MATERIALS
ABSTRACT OF THE DISCLOSURE
An apparatus for heating granular material such as mustard seeds, peanuts, cacao beans, coffee beans, and soybeans includes an inclined cylindrical drum forming a heating chamber. The material is fed to the heating chamber through an upper tube which also feeds hot gas into the chamber. Microwave energy is fed into the lower end of the chamber which is provided with an internal structure of concentric rings and longitudinal strip members to assist in mixing of the material.
ABSTRACT OF THE DISCLOSURE
An apparatus for heating granular material such as mustard seeds, peanuts, cacao beans, coffee beans, and soybeans includes an inclined cylindrical drum forming a heating chamber. The material is fed to the heating chamber through an upper tube which also feeds hot gas into the chamber. Microwave energy is fed into the lower end of the chamber which is provided with an internal structure of concentric rings and longitudinal strip members to assist in mixing of the material.
Description
~3~ 7 This invention relates to apparatus for heating granular materials such as, for example, mustard seeds, peanuts, cacao beans, coffee beans, and soybeans.
Particularly in the food industry the heating of granular materials is frequently required. Conventional heating methods have been used and, more recently, the use o micro-wave heating has been proposed.
It is an object of the present invention to provide an improved apparatus for heating granular materials effic-iently and more uniformly than previous microwave heatingmethods.
Accordingly the present invention provides an apparatus ~or heating granular materials including an in-clined cylindrical metal heating chamber provided with an upper inlet and a lower outlet for said granular material, means for rotating the heating chamber about its longitudin-al axis, means for supplying microwave energy to the heating chamber, a tubular portion connected to said upper inlet for supplying said granular material to said heating chamber, means for supplying hot gas to said heating chamber through said tubular portion, means for supplying said granular mat-erial to said tubular portion whereby the granular material acts as an air lock to ensure that substantially all said hot gas is fed to said heating chamber, the dimensions of said tubular portion being such that the radius of the tubular portion is less than A/3.412 to substantially reduce the escape of microwave energy, where ~ is the freespace wavelength of the microwave energy used.
One embodiment of theinvention will now be des-cribed, by way of example, with reference to the singlefigure of the accompanying drawing which is a diagrammatic representation of a microwave system for heating granular materials.
~ Referring to the figure a cylindrical metal heating chamber 2 is;provided and is inclined at an angle of 15-20 to the horizontal plane. An upper inlet 4 and a lower outlet 6 is provided for the heating chamber.
As shown, the lower outlet 6 is actually one of ,, ~e
Particularly in the food industry the heating of granular materials is frequently required. Conventional heating methods have been used and, more recently, the use o micro-wave heating has been proposed.
It is an object of the present invention to provide an improved apparatus for heating granular materials effic-iently and more uniformly than previous microwave heatingmethods.
Accordingly the present invention provides an apparatus ~or heating granular materials including an in-clined cylindrical metal heating chamber provided with an upper inlet and a lower outlet for said granular material, means for rotating the heating chamber about its longitudin-al axis, means for supplying microwave energy to the heating chamber, a tubular portion connected to said upper inlet for supplying said granular material to said heating chamber, means for supplying hot gas to said heating chamber through said tubular portion, means for supplying said granular mat-erial to said tubular portion whereby the granular material acts as an air lock to ensure that substantially all said hot gas is fed to said heating chamber, the dimensions of said tubular portion being such that the radius of the tubular portion is less than A/3.412 to substantially reduce the escape of microwave energy, where ~ is the freespace wavelength of the microwave energy used.
One embodiment of theinvention will now be des-cribed, by way of example, with reference to the singlefigure of the accompanying drawing which is a diagrammatic representation of a microwave system for heating granular materials.
~ Referring to the figure a cylindrical metal heating chamber 2 is;provided and is inclined at an angle of 15-20 to the horizontal plane. An upper inlet 4 and a lower outlet 6 is provided for the heating chamber.
As shown, the lower outlet 6 is actually one of ,, ~e
- 2 - ~234~7 several discharge tubes circumferentially spaced around the lower end of the heating chamber 2 and, in practice, feeding into an enclosed outlet conduit 8 for collection of the treated granular material through a discharge chute 9.
A tubular portion in the form of tube 10 is con-nected to the inlet 4 whilst rotation o~ the heatiny chamber about its axis is achieved by way of a drum motor, chain drive and support bearing arrangement 12. Hot gas or air is supplied to the free end of tube 10 from an air/gas source 14 and the dimensions of tube 10 are so designed that the radius of the tubular portion 10 is less than ~/3.412 to substantially reduce the escape of microwave energy where is the freespace wavelength of the microwave energy.
The granular material is fed into tube 10 from a hopper 16 by way of a substantially vertical feed tube 18.
A feed motor 20 controls rotation of a paddle mechanism 22 to ensure feeding of the granular material 24 to the chamber 2 at a controlled rate. ~s will ~e evident, the granular ma-terial itself acts as an air lock to ensure that substantially all the hot gas is fed to the heating chamber 2. After heat-ing, the granular material is discharged through the plurality of radial discharge tubes 5. The material may become airborne within the drum, to produce better drying of the material.
The cylindrical metal heating chamber 2 is provided with thermal insulation 26 to reduce heat loss to the surround-ings and also with an internal structure arrangement 28, made of Teflon*, ceramic or metal, to control the flow of granular material through the apparatus. The internal structure ar-rangement provides better mixing and consists basical]y of a plurality of concentric rings and longitudinal strips to form pockets or compartments. The preferred material for the structure is Teflon* but in caseswhere extremely high temper-atures are anticipated metal may be used if care is taken to avoid sharp edges which could result in electrical breakdown.
Thus, there is provided a cascading rotary processor consisting of an inclined rotating cylinder with an internal structure to control the tumbling action and product movement through the drum. Product residence time is primarily a function of * Trademark _ 3 _ ~ ~3~7~
the rate of rotation of the drum for a given incline and internal structure. Feed rate is controlled separatelv.
As shown, microwave energy from a source 30 is supplied through an axially located tube 32 and teflon window 34 to the interior of the chamber 2~ A rotating joint and choke arrangement 36 is provided at the junction of tube 32 and chamber 2 to prevent microwave leakage.
The drum forms a multi-mode cavity and hence its dimensions are not critical. The dimensions of the discharge tubes 6 and the loading tube 10 are such that microwave energy cannot escape. The principle of "waveguide beyond cut-off"
is utilized to prevent leakage, resulting also in a simpler mechanical arrangement.
In use, the granular material is fed into the hopper 16 and thence through tube 10 to the interior of revolving drum 2. After suitable heating and treatment by the microwave energy, the material exits through the lower outlets 6. The continuous tumbling of the material results in more uniform heating thereof.
It will be seen that the above-described embodiment provides a cascading rotary drier configuration in combination with microwave power. The provision of an internal structure forming "compartments" facilitates control of the flow of material through the processor whilst the use of the product to form an "air lock" ensures that substantially all the process air or gas is fed to the processing drum. One unit operated successfully with microwave energy at 2450 MHz and at power levels up to 12 Kw but it will be' understood that these values are in no way restrictive. The processor was useful in dealing with, for example, the inactivation of myrosinase enzyme in mustard seed, destruction of nematospora in mustard seed, destruction of tripsin inhibitor in soybeans, and the destruction of aflatoxins in peanuts.
The compartmental structure used resulted in a well-controlled flow rate which is particularly advantageous and has been difficult to achieve with other apparatus~
The apparatus could conveniently, without much modi-fication, be used in a variety of different applications , ~3~7~
such as drying, roasting, enzyme inactivation, pasteuriza-tion or sterilization.
In use it was found that a processor utilizing a drum 1 ft in diameter, 36 in. in length, rotating at about 1 RPM and operating at a power level of 5.5 Kw at a frequency of 2450 MHz was capable of processing mustard seed for the purpose of inactivating the myrosinase enzyme at a rate of 60 kg per hour.
It will be readily apparent to a person skilled in the art that a number of variations and modifications can be made without departing from the true spirit of the invention which will now be pointed out in the appended claims.
..
A tubular portion in the form of tube 10 is con-nected to the inlet 4 whilst rotation o~ the heatiny chamber about its axis is achieved by way of a drum motor, chain drive and support bearing arrangement 12. Hot gas or air is supplied to the free end of tube 10 from an air/gas source 14 and the dimensions of tube 10 are so designed that the radius of the tubular portion 10 is less than ~/3.412 to substantially reduce the escape of microwave energy where is the freespace wavelength of the microwave energy.
The granular material is fed into tube 10 from a hopper 16 by way of a substantially vertical feed tube 18.
A feed motor 20 controls rotation of a paddle mechanism 22 to ensure feeding of the granular material 24 to the chamber 2 at a controlled rate. ~s will ~e evident, the granular ma-terial itself acts as an air lock to ensure that substantially all the hot gas is fed to the heating chamber 2. After heat-ing, the granular material is discharged through the plurality of radial discharge tubes 5. The material may become airborne within the drum, to produce better drying of the material.
The cylindrical metal heating chamber 2 is provided with thermal insulation 26 to reduce heat loss to the surround-ings and also with an internal structure arrangement 28, made of Teflon*, ceramic or metal, to control the flow of granular material through the apparatus. The internal structure ar-rangement provides better mixing and consists basical]y of a plurality of concentric rings and longitudinal strips to form pockets or compartments. The preferred material for the structure is Teflon* but in caseswhere extremely high temper-atures are anticipated metal may be used if care is taken to avoid sharp edges which could result in electrical breakdown.
Thus, there is provided a cascading rotary processor consisting of an inclined rotating cylinder with an internal structure to control the tumbling action and product movement through the drum. Product residence time is primarily a function of * Trademark _ 3 _ ~ ~3~7~
the rate of rotation of the drum for a given incline and internal structure. Feed rate is controlled separatelv.
As shown, microwave energy from a source 30 is supplied through an axially located tube 32 and teflon window 34 to the interior of the chamber 2~ A rotating joint and choke arrangement 36 is provided at the junction of tube 32 and chamber 2 to prevent microwave leakage.
The drum forms a multi-mode cavity and hence its dimensions are not critical. The dimensions of the discharge tubes 6 and the loading tube 10 are such that microwave energy cannot escape. The principle of "waveguide beyond cut-off"
is utilized to prevent leakage, resulting also in a simpler mechanical arrangement.
In use, the granular material is fed into the hopper 16 and thence through tube 10 to the interior of revolving drum 2. After suitable heating and treatment by the microwave energy, the material exits through the lower outlets 6. The continuous tumbling of the material results in more uniform heating thereof.
It will be seen that the above-described embodiment provides a cascading rotary drier configuration in combination with microwave power. The provision of an internal structure forming "compartments" facilitates control of the flow of material through the processor whilst the use of the product to form an "air lock" ensures that substantially all the process air or gas is fed to the processing drum. One unit operated successfully with microwave energy at 2450 MHz and at power levels up to 12 Kw but it will be' understood that these values are in no way restrictive. The processor was useful in dealing with, for example, the inactivation of myrosinase enzyme in mustard seed, destruction of nematospora in mustard seed, destruction of tripsin inhibitor in soybeans, and the destruction of aflatoxins in peanuts.
The compartmental structure used resulted in a well-controlled flow rate which is particularly advantageous and has been difficult to achieve with other apparatus~
The apparatus could conveniently, without much modi-fication, be used in a variety of different applications , ~3~7~
such as drying, roasting, enzyme inactivation, pasteuriza-tion or sterilization.
In use it was found that a processor utilizing a drum 1 ft in diameter, 36 in. in length, rotating at about 1 RPM and operating at a power level of 5.5 Kw at a frequency of 2450 MHz was capable of processing mustard seed for the purpose of inactivating the myrosinase enzyme at a rate of 60 kg per hour.
It will be readily apparent to a person skilled in the art that a number of variations and modifications can be made without departing from the true spirit of the invention which will now be pointed out in the appended claims.
..
Claims (6)
1. Apparatus for heating granular materials including an inclined cylindrical metal heating chamber provided with an upper inlet and a lower outlet for said granular material, means for rotating the heating chamber about its longitudinal axis, means for supplying microwave energy to the heating chamber, a tubular portion connected to said upper inlet for supplying said granular material to said heating chamber, means for supplying hot gas to said heating chamber through said tubular portion, means for supplying said granular material to said tubular portion whereby the granular material acts as an air lock to ensure that substantially all said hot gas is fed to said heating chamber, the dimensions of said tubular portion being such that the radius of the tubular portion is less than .lambda./3.412 to substantially reduce the escape of microwave energy, where .lambda. is the freespace wavelength of the microwave energy used.
2. Apparatus according to claim 1 wherein said heating chamber is within a drum having its longitudinal axis inclined to the horizontal plane, said means for supply-ing granular material to said tubular portion comprises a hopper containing said material and connected to said tubular portion by way of a substantially vertical further tubular portion.
3. Apparatus according to claim 2 including ro-tating paddle means to ensure feeding of the granular material to said heating chamber at a controlled rate.
4. Apparatus according to claim 1, 2 or 3 wherein an internal structure is provided within said heating chamber, said internal structure comprises a plurality of concentric ring members and longitudinal strip members forming compart-ments within the heating chamber.
5. Apparatus according to claim 1, 2 or 3 wherein said upper inlet is substantially on the longitudinal axis of said heating chamber.
6. Apparatus according to claim 1, 2 or 3 wherein, a yet further tubular portion is provided, said yet further tubular portion having one end connected axially into said heating chamber at its lower end by way of a teflon window portion and a rotating joint and choke arrangement, the other end of said yet further tubular portion being supplied with microwave energy from a microwave source.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000479178A CA1234877A (en) | 1985-04-15 | 1985-04-15 | Apparatus for heating granular materials |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000479178A CA1234877A (en) | 1985-04-15 | 1985-04-15 | Apparatus for heating granular materials |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1234877A true CA1234877A (en) | 1988-04-05 |
Family
ID=4130277
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000479178A Expired CA1234877A (en) | 1985-04-15 | 1985-04-15 | Apparatus for heating granular materials |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1234877A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0740904A1 (en) * | 1995-05-02 | 1996-11-06 | Societe Des Produits Nestle S.A. | Improving wettability of powders by microwave treatment |
| NL1006690C2 (en) * | 1997-07-30 | 1999-02-02 | Marinus Minkjan | Microwave product processing machine |
| WO2011042356A1 (en) * | 2009-10-05 | 2011-04-14 | Nestec S.A. | Method for preparing a beverage from a beverage powder and apparatus for implemeting the method |
-
1985
- 1985-04-15 CA CA000479178A patent/CA1234877A/en not_active Expired
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0740904A1 (en) * | 1995-05-02 | 1996-11-06 | Societe Des Produits Nestle S.A. | Improving wettability of powders by microwave treatment |
| WO1996034536A1 (en) * | 1995-05-02 | 1996-11-07 | Societe Des Produits Nestle S.A. | Improving wettability of powder by microwave treatment |
| NL1006690C2 (en) * | 1997-07-30 | 1999-02-02 | Marinus Minkjan | Microwave product processing machine |
| WO2011042356A1 (en) * | 2009-10-05 | 2011-04-14 | Nestec S.A. | Method for preparing a beverage from a beverage powder and apparatus for implemeting the method |
| CN102612331A (en) * | 2009-10-05 | 2012-07-25 | 雀巢产品技术援助有限公司 | Method for preparing a beverage from a beverage powder and apparatus for implemeting the method |
| US8802172B2 (en) | 2009-10-05 | 2014-08-12 | Nestec S.A. | Method for preparing a beverage from a beverage powder and apparatus for implementing the method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |