How to choose a binactivator
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There are two main different criteria to choosing a Bin Activator: 1- Complete and consistent discharging emptying of the silo 2- Mass-flow emptying Mass-flow may be obtained by using a Bin Activator with a diameter of approximately 70% of the silo diameter. The silo cone angle must also be between 65° and 70°. Mass-flow refers to the level emptying of the silo ensuring all product moves at the same rate; however, based on experience, some flexibility is required. In the 60's, the method on selecting the optimum diameter of the Bin Activator was modified. The diameter of the Bin Activator will change (increase) in relation of the flowability properties of the product | |||
| Class | Features | Examples | Choice of the Bin Activator Diam /Silo diam |
| I | Free flowing products | Cement Plastic pellets |
NO BIN ACTIVATOR 2/3 if mass-flow required |
| II A | Low flowing products tending to stick | Wet sand Kaolin |
1/3 up to 1/2 2/3 if mass-flow required |
| II B | Low flowing products tending to fuse | Corn stach Wheat flour |
1/3 up to 1/2 2/3 if mass-flow required |
| III A | Bad flowing products tending to stick | Titan dioxide Potato flour |
2/3 |
| III B | Bad flowing products tending to fuse | Talc Warm plaster |
2/3 |
| IV | Fibrous products | Asbestos Beans |
2/3 to 1 |
| The Bin Activator is sized to prevent a bridge occuring inside the silo. The aim is to use a Bin Activator larger than the anticipated position of the bridge. A small Bin Activator may empty the silo without bridging for some products. But it may create a chimney effect or "rat hole". The chimney is created by limited activation of the product on the side of the silo. The chimney itself is not a risk but the possible "crash down" of the remaining product may be. This is caused by a void in the center of the silo, where product can fall without any control. Two major problems may occur in isolation or together: - an overpressure in the lower part of the silo caused by the product falling down the chimney - a negative pressure in the upper part of the silo caused by the difference between the atmospheric pressure and the vacuum given by the falling product. The storage and extraction of powders is a specialized field which requires experience and know-how. Every storage application is unique and the silo manufacturer can use various combinations of diameter and heights to provide a good solution. | |||
| PRODUCT* | LOCATION OF THE SILO | ||
| FLOWABILITY | CLIMATE | ||
| BULK DENSITY | SUNLIGHT | ||
| MOISTURE CONSTENT | SECTION (ROUND,SQUARE,RECTANGULAR...) | ||
| THROUGHOUT CAPACITY |
DIAMETER AND HEIGHT | ||
| TYPE OF FILLING | CONE ANGLE | ||
| STORAGE TIME | MATERIAL OF CONSTRUCTION | ||
| OVER/NEGATIVE PRESSURE | TEMPORIZING OF THE MOTOR (S) | ||
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(This list is not exhaustive) | |||
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After 40 years of experience, this theory has benefited many installations. | |||
| Caution : depending on the storage conditions, some products may becom sticky and flushing. The hydraulic ray (section regarding the diameter) may have an incidence on the choice of the Bin Activator. | |||
