Many plant operate with a variable speed ID fan without any damper in front. Some precautions should always be taken to avoid overheating of the fan. For example:
- proper preheating procedure. Usually preheating is started with only the stack fan running at low speed and no power on the ID fan motor.
- Proper interlocks between raw meal and fuels
It should also be ensured that the ID fan can be rotated continuously (even at low speed) if subjected to high temperature (i.e more than 400-450°C, needs to be checked with fan manufacturer), otherwise, the shaft may bend under the weight of the impeller.
But I am wondering about the reason why you would remove an existing damper. You speak about the pressure drop, so I guess this is to increase production. But the pressure drop of a fully open damper is very low, so this should not make a very significant difference.
To increase production in a plant bottlenecked by ID fan, there are several possibilities (besides replacing the ID fan that is):
The best way is of course to perform a complete study of the pressure drop across the system to determine where a modification (for example cyclone replacement) could bring the most benefit.
Some specific tools also exist:
- Installing A-Tec Hurrivane on the top cyclone can significantly reduce the pressure drop of these cyclone, but will increase entrained dust to the filter
- If there is some spare power on the ID fan motor, cooling the gas before the fan by installing a water spray in the downcomer will increase gas density and thus fan capacity.
Best regards