I would like to ask everyone about the problem of fan pressure and air volume after variable frequency induction draft fan of boiling drying bed.
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Please tell me: Our company has two ebullating beds, and each has an induced draft fan to keep the material in the bed blown up. It turns out that because the fan power is relatively large, the valve only needs to be opened 1/3, which causes a lot of powder leakage in our ebullated bed (material leaks from the small holes in the bed to the bottom). Later, a frequency converter was added to the fan of an ebullated bed to slow it down. By increasing the opening of the valve, the leakage of material is reduced by 2/3, and the fine powder carried away by the induced air into the powder collector is also reduced by 2/3. However, the fluidized bed without a frequency converter still leaks a lot of material and fine powder (even after switching to an induced draft fan with a smaller wind pressure and air volume, the motor power has not changed). I would like to ask, what is the reason for this? Why does adding a frequency converter allow materials to fall and fine powder to escape? * * reduce? How did the wind pressure difference and wind speed inside the bed change before and after the inverter was installed?
The distribution plate leaks particles and at the same time takes away fine particles. These two points cannot be explained by the air volume. There is a possibility: Because there is a problem with the gas circuit design, after the valve is closed, the gas flows in a biased manner, the gas distribution is not good, and particles leak out in places where the gas velocity is low. At the same time, the local air velocity is too high, taking away a lot of fine particles.
This phenomenon is called fluttering, and the fluidization speed is greater than the settling speed of some particles. The solution is to add separation equipment such as a cyclone separator, or increase the total height of the equipment or create an expansion section on the upper part of the equipment to reduce the speed. If your material leaks downward, it means that the design of your distribution plate is unreasonable. The speed passing through the distribution plate must be greater than the clogging speed of the particles. In other words, the pressure drop of your distribution plate is relatively small and the opening rate is large.