CA1199170A - Grain aeration fan - Google Patents
Grain aeration fanInfo
- Publication number
- CA1199170A CA1199170A CA000417262A CA417262A CA1199170A CA 1199170 A CA1199170 A CA 1199170A CA 000417262 A CA000417262 A CA 000417262A CA 417262 A CA417262 A CA 417262A CA 1199170 A CA1199170 A CA 1199170A
- Authority
- CA
- Canada
- Prior art keywords
- casing
- impeller
- fan
- motor
- air flow
- 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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04D—NON-POSITIVE-DISPLACEMENT PUMPS
- F04D19/00—Axial-flow pumps
- F04D19/02—Multi-stage pumps
- F04D19/024—Multi-stage pumps with contrarotating parts
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F26—DRYING
- F26B—DRYING SOLID MATERIALS OR OBJECTS BY REMOVING LIQUID THEREFROM
- F26B21/00—Arrangements or duct systems, e.g. in combination with pallet boxes, for supplying and controlling air or gases for drying solid materials or objects
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structures Of Non-Positive Displacement Pumps (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A grain aeration fan for blowing air into a perforated tube or the like in a storage bin includes a pair of counter-rotating impellers mounted on opposite sides of the centre in a cylindrical casing at a distance of 1 - 3 inches apart. The impellers, which are driven by separate motors, include the same number of blades, which are oppositely pitched. The air-flow through the casing is higher than the total airflow which would be produced by the two impellers operating independently of each other.
A grain aeration fan for blowing air into a perforated tube or the like in a storage bin includes a pair of counter-rotating impellers mounted on opposite sides of the centre in a cylindrical casing at a distance of 1 - 3 inches apart. The impellers, which are driven by separate motors, include the same number of blades, which are oppositely pitched. The air-flow through the casing is higher than the total airflow which would be produced by the two impellers operating independently of each other.
Description
7~
This inven-tion relates to a fan and in par-ticular to an aeration fan for clrying grain and other bin stored granular material.
In the recent past the aeration of grain in grain bins has replaced the drying of grain prior to storage. In other words, instead of drying grain and then depositing the grain in a storage bin i-t has become common practice to aerate the grain by continuously blowing air through the grain. Aeration of the grain cools and drys the grain, thereby preventing spoilage during storage. Normally, aeration is effected by using a 12" to 18"
diameter perforated tube or tubes on the bin floor. The tube extends out-wardly through the side of the bin to an electric fan.
The three types of fans commonly used in -the aeration of grain are the axial, the vane axial and the centrifugal fan. The axial is the fan most commonly used because the axial is the simplest and most economical of the three types of fan. The axial fan includes a cylindrical casing, which con-tains a motor and an axial impeller. The axial fan is readily portable. The disadvantages of the axial fan are its low efficiency and high noise level.
The vane axial fan is the same as the axial fan, excep-t that curved vanes are provided downstream of the impeller in the direction of air Elow.
The vanes reduce air turbulence caused by the impeller and thus improve Ean perEormarlce. Of course, the vane a~ial fan is more expensive than the simple axial fan.
The centrifugal fan is available in high and low speed versions.
1~11 centrifugal fans are more expensive than their axial couterparts.
('entrifugual fans possess the advantage of a low noise level. The high ,peed centrifugal fan uses an impeller having a smaller diameter than that ~ .~ .
L7C~
of the low speed centriEuyal fan and has the lowest air Elow of all types of fan. The low speed centrifugal fan is the best perEorming fan available bu-t, in general, is quite heavy and expensive. A low speed centrifugal fan must be moved using a tractor or forklift and costs -two or more times as much as an axial fan of the same size. Another disadvantaye of centrifugal fans is that motor heat is wasted because the motor is not mounted in the air stream from the impeller.
The object of the present invention is to solve, at least partially, most of the problems mentioned above.
Accordingly, the present invention relates to an aeration fan for drying granular material comprising a cylindrical casing, first motor means in said casing; first impe}ler means connected to said first motor means for driving air through said casing from an open inlet end through an open outlet end of said casing; second motor means in said casing downstream of said first impeller means in the direction of air flow; and second impeller means connec-ted to said second motor means for rotation in a direction opposite to the direction of rot:ation of said first impeller means, said first and second impeller means including equal blades of opposite pitch and said first and second impeller means being spaced a short distance apart, whereby the air Elow through said casing is greater than the total air flow created by said first and second impsllers individually.
The invention will now be described with reference to the a~companying drawing, a single figure which is a schematic, longitudinal sectional view of a preferred embodiment of a fan in accordance with the present inven-tion.
9:~L7(~
With reference to the drawing, the fan of the present invention which is generally indicated at 1 includes a cylindrical casing 2, which is open at each end 3 and 4. Air introduced into the inlet end 3 and discharged -through the outlet end 4. Normally the outlet end 4 of the casing 2 is connected to a perforated tube (not shown) for aerating a grain bin.
A pair of electric motors 5 and 6 are mounted in the casing 2. The first motor 5 is on the upstream (in the direction of air flow) side of the centre of the casing 2, and the motor 6 is on the downstream side of the centre of the casing. An impeller 7 is mounted on a drive shaft 8 of the motor 5 and an impeller 9 is mounted in a drive shaft 10 of the motor 6. Thus, the impellers 7 and 10 oppose each other on elther side of the centre of the casing 2. The impellers 7 and 9 have an equal number of opposite pitch blades or vanes ll and 12 respectively.
During operation the impeller 7 rotates in one direction and impell-er 9 rotates in the opposite direc-tion. Because the blades 11 and 12 have equal but opposite pitch, air flow is in one direction through the casing 2.
It has been found that this arrangement increases air flow at operating pressures. The air flow of any fan decreases as the pressure (resistance to air flow) increases. Air escapes back through the fan blades rather than beincJ Eorced through the outlet end 4 of the casing 2. In any axial fan, as the pressure increases air starts to swirl with the impeller. The swirling of air in the same direction as fan rota-tion has the same effec-t as a reduction in motor speed. The problem becomes worse as the pressure increases, result-ing in poor fan performance. With counter-rotating fans or impellers 7 and 9 ~hen air begins to swirl in the same direction as the impeller 7, such air is swirling in the direction opposite to the direction of rotation of the impeller 9. This has the same effect as increasing the speed of the second motor 6. Therefore, when two oppositely rota-ting impellers at the proper distance apart are operated in a single casing, -the normal reduced efficiency of the first impeller is regained by the second impeller. Two fan arrange-ments with the impellers rotating in the same direction produce one-third to one-half the air flow of equivalent two impeller fans of the type described herein.
In tests involving counter-rotating impellers, it was found that the impellers should be quite close together (1 to 3 inches apart) for optimum performance. Counter-rotating fans have been found to perform better than any of the three types of fan (axial, vane axial or centrifugal) of equivalent size, with reduced power consumption in some cases. Noise levels were equal to those of axial or vane axial fans.
The two motor concept has the advantage that one can be s-tarted after the other, thereby reducing the surge of power normally required to start one motor.
Moreover, the two impeller fan is relatively inexpensive to produce.
A larger axial fan is required to produce the same air flow as a smaller ~ counter-rotating, -two impeller fan of the type described herein. The main cost of an axial or coun-ter-rotating fan is the motor. Whereas two small motors can be used in the fan of the present invention, one large motor is used in -the axial fan. It has been found that the large motor required to produce the same air flow as the double impeller fan is more expensive than the two small motors used in the double impeller fan.
During testing it was found that there is a substantial increase in air -temperature due to motor heat. The hot air thus produced aids the grain drying process.
The counter-rotating Eans described in -the foregoing are ~ horse-power (two motors each of 2 horsepower) with 18 inch diarneter impellers.
In closing it is worth noting that the present inven-tor does not claim to have invented the concept of the two stage counter-rotating fan.
What the inventor has done is to conceive the idea of using the concept in a grain aeration fan and, by research, proved that the concept can indeed be used with advantage in grain aeration.
This inven-tion relates to a fan and in par-ticular to an aeration fan for clrying grain and other bin stored granular material.
In the recent past the aeration of grain in grain bins has replaced the drying of grain prior to storage. In other words, instead of drying grain and then depositing the grain in a storage bin i-t has become common practice to aerate the grain by continuously blowing air through the grain. Aeration of the grain cools and drys the grain, thereby preventing spoilage during storage. Normally, aeration is effected by using a 12" to 18"
diameter perforated tube or tubes on the bin floor. The tube extends out-wardly through the side of the bin to an electric fan.
The three types of fans commonly used in -the aeration of grain are the axial, the vane axial and the centrifugal fan. The axial is the fan most commonly used because the axial is the simplest and most economical of the three types of fan. The axial fan includes a cylindrical casing, which con-tains a motor and an axial impeller. The axial fan is readily portable. The disadvantages of the axial fan are its low efficiency and high noise level.
The vane axial fan is the same as the axial fan, excep-t that curved vanes are provided downstream of the impeller in the direction of air Elow.
The vanes reduce air turbulence caused by the impeller and thus improve Ean perEormarlce. Of course, the vane a~ial fan is more expensive than the simple axial fan.
The centrifugal fan is available in high and low speed versions.
1~11 centrifugal fans are more expensive than their axial couterparts.
('entrifugual fans possess the advantage of a low noise level. The high ,peed centrifugal fan uses an impeller having a smaller diameter than that ~ .~ .
L7C~
of the low speed centriEuyal fan and has the lowest air Elow of all types of fan. The low speed centrifugal fan is the best perEorming fan available bu-t, in general, is quite heavy and expensive. A low speed centrifugal fan must be moved using a tractor or forklift and costs -two or more times as much as an axial fan of the same size. Another disadvantaye of centrifugal fans is that motor heat is wasted because the motor is not mounted in the air stream from the impeller.
The object of the present invention is to solve, at least partially, most of the problems mentioned above.
Accordingly, the present invention relates to an aeration fan for drying granular material comprising a cylindrical casing, first motor means in said casing; first impe}ler means connected to said first motor means for driving air through said casing from an open inlet end through an open outlet end of said casing; second motor means in said casing downstream of said first impeller means in the direction of air flow; and second impeller means connec-ted to said second motor means for rotation in a direction opposite to the direction of rot:ation of said first impeller means, said first and second impeller means including equal blades of opposite pitch and said first and second impeller means being spaced a short distance apart, whereby the air Elow through said casing is greater than the total air flow created by said first and second impsllers individually.
The invention will now be described with reference to the a~companying drawing, a single figure which is a schematic, longitudinal sectional view of a preferred embodiment of a fan in accordance with the present inven-tion.
9:~L7(~
With reference to the drawing, the fan of the present invention which is generally indicated at 1 includes a cylindrical casing 2, which is open at each end 3 and 4. Air introduced into the inlet end 3 and discharged -through the outlet end 4. Normally the outlet end 4 of the casing 2 is connected to a perforated tube (not shown) for aerating a grain bin.
A pair of electric motors 5 and 6 are mounted in the casing 2. The first motor 5 is on the upstream (in the direction of air flow) side of the centre of the casing 2, and the motor 6 is on the downstream side of the centre of the casing. An impeller 7 is mounted on a drive shaft 8 of the motor 5 and an impeller 9 is mounted in a drive shaft 10 of the motor 6. Thus, the impellers 7 and 10 oppose each other on elther side of the centre of the casing 2. The impellers 7 and 9 have an equal number of opposite pitch blades or vanes ll and 12 respectively.
During operation the impeller 7 rotates in one direction and impell-er 9 rotates in the opposite direc-tion. Because the blades 11 and 12 have equal but opposite pitch, air flow is in one direction through the casing 2.
It has been found that this arrangement increases air flow at operating pressures. The air flow of any fan decreases as the pressure (resistance to air flow) increases. Air escapes back through the fan blades rather than beincJ Eorced through the outlet end 4 of the casing 2. In any axial fan, as the pressure increases air starts to swirl with the impeller. The swirling of air in the same direction as fan rota-tion has the same effec-t as a reduction in motor speed. The problem becomes worse as the pressure increases, result-ing in poor fan performance. With counter-rotating fans or impellers 7 and 9 ~hen air begins to swirl in the same direction as the impeller 7, such air is swirling in the direction opposite to the direction of rotation of the impeller 9. This has the same effect as increasing the speed of the second motor 6. Therefore, when two oppositely rota-ting impellers at the proper distance apart are operated in a single casing, -the normal reduced efficiency of the first impeller is regained by the second impeller. Two fan arrange-ments with the impellers rotating in the same direction produce one-third to one-half the air flow of equivalent two impeller fans of the type described herein.
In tests involving counter-rotating impellers, it was found that the impellers should be quite close together (1 to 3 inches apart) for optimum performance. Counter-rotating fans have been found to perform better than any of the three types of fan (axial, vane axial or centrifugal) of equivalent size, with reduced power consumption in some cases. Noise levels were equal to those of axial or vane axial fans.
The two motor concept has the advantage that one can be s-tarted after the other, thereby reducing the surge of power normally required to start one motor.
Moreover, the two impeller fan is relatively inexpensive to produce.
A larger axial fan is required to produce the same air flow as a smaller ~ counter-rotating, -two impeller fan of the type described herein. The main cost of an axial or coun-ter-rotating fan is the motor. Whereas two small motors can be used in the fan of the present invention, one large motor is used in -the axial fan. It has been found that the large motor required to produce the same air flow as the double impeller fan is more expensive than the two small motors used in the double impeller fan.
During testing it was found that there is a substantial increase in air -temperature due to motor heat. The hot air thus produced aids the grain drying process.
The counter-rotating Eans described in -the foregoing are ~ horse-power (two motors each of 2 horsepower) with 18 inch diarneter impellers.
In closing it is worth noting that the present inven-tor does not claim to have invented the concept of the two stage counter-rotating fan.
What the inventor has done is to conceive the idea of using the concept in a grain aeration fan and, by research, proved that the concept can indeed be used with advantage in grain aeration.
Claims (4)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An aeration fan for drying granular material comprising a cylindrical casing, first motor means in said casing; first impeller means connected to said first motor means for driving air through said casing from an open inlet end through an open outlet end of said casing;
second motor means in said casing downstream of said first impeller means in the direction of air flow; and second impeller means connected to said second motor means for rotation in a direction opposite to the direction of rotation of said first impeller means, said first and second impeller means including equal blades of opposite pitch and said firs-t and second impeller means being spaced a short distance apart whereby the air flow through said casing is greater than the total air flow created by said first and second impellers individually.
second motor means in said casing downstream of said first impeller means in the direction of air flow; and second impeller means connected to said second motor means for rotation in a direction opposite to the direction of rotation of said first impeller means, said first and second impeller means including equal blades of opposite pitch and said firs-t and second impeller means being spaced a short distance apart whereby the air flow through said casing is greater than the total air flow created by said first and second impellers individually.
2. An aeration fan according to claim 1, wherein said first impeller means is downstream of said first motor means in the direction of air flow;
and said second impeller means is downstream of said first impeller means and upstream of said second motor means in the direction of air flow.
and said second impeller means is downstream of said first impeller means and upstream of said second motor means in the direction of air flow.
3. An aeration fan according to claim 1 wherein said first and second impeller means are spaced apart a distance of 1 to 3 inches.
4. An aeration fan according to claim 3 wherein each said first and second motor means comprises a 2 horsepower electric motor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000417262A CA1199170A (en) | 1982-12-08 | 1982-12-08 | Grain aeration fan |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000417262A CA1199170A (en) | 1982-12-08 | 1982-12-08 | Grain aeration fan |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1199170A true CA1199170A (en) | 1986-01-14 |
Family
ID=4124106
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000417262A Expired CA1199170A (en) | 1982-12-08 | 1982-12-08 | Grain aeration fan |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1199170A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2545767A (en) * | 2015-09-28 | 2017-06-28 | Beijing Toozen Lab Tech Co Ltd | Improved Axial Fan |
-
1982
- 1982-12-08 CA CA000417262A patent/CA1199170A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2545767A (en) * | 2015-09-28 | 2017-06-28 | Beijing Toozen Lab Tech Co Ltd | Improved Axial Fan |
| GB2545767B (en) * | 2015-09-28 | 2018-01-10 | Beijing Toozen Lab Tech Co Ltd | Contra-rotating axial-flow fan |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |