cokeguy
Electrical
- Jan 29, 2006
- 117
We temporarily replaced a damaged 56" diameter, 100 ft tall fiberglass smokestack of a scrubber with a smokestack from an unused scrubber, with same height but a 42.5" diameter. My question is, how can I calculate the extra load on the induced draft fan caused by the smaller diameter smokestack? We have an ongoing debate here at the plant about whether the smaller smokestack is the cause of the ID fan´s VFD-driven 250 HP motor running at its upper limits, or else that we could have a undetected problem (air leakage) somewhere else at the scrubber or furnace. Previous operating conditions don´t help much because of different process conditions.
We already ordered a replacement smokestack, original dimensions, but we won´t have it for at least a couple of months, and the scrubber will undergo a major change in a few days which will probably overload the ID fan´s motor and force us to take it out of operation. If we sit still hoping for the new smokestack to correct the problem and it turns out not to be a significant factor, it will mean more downtime, hurries, etc... so if anybody can guide me or comment on a similar situation I woul appreciate it a lot. As general process data, fan is operating at about 1000 RPM, I don´t have the exact volume of air being moved by the fan but it is basically the flue gas of a furnace after passing the scrubber, so it means about 10,000 CFMs of combustion air plus fuel plus water vapor, pressure differential between fan´s inlet and outlet is typically about 10"H2O, fan motor is 250 HP, VFD driven, typically runnig close to full load amps and 60 Hz.
Thanks for your help, comments and suggestions.
We already ordered a replacement smokestack, original dimensions, but we won´t have it for at least a couple of months, and the scrubber will undergo a major change in a few days which will probably overload the ID fan´s motor and force us to take it out of operation. If we sit still hoping for the new smokestack to correct the problem and it turns out not to be a significant factor, it will mean more downtime, hurries, etc... so if anybody can guide me or comment on a similar situation I woul appreciate it a lot. As general process data, fan is operating at about 1000 RPM, I don´t have the exact volume of air being moved by the fan but it is basically the flue gas of a furnace after passing the scrubber, so it means about 10,000 CFMs of combustion air plus fuel plus water vapor, pressure differential between fan´s inlet and outlet is typically about 10"H2O, fan motor is 250 HP, VFD driven, typically runnig close to full load amps and 60 Hz.
Thanks for your help, comments and suggestions.