mjpetrag
Mechanical
- Oct 16, 2007
- 224
Wanted to get anyone's thoughts and experiences on switching from steam turbine driven boiler draft fans to VFD driven fans. We are looking at significant capital spend rehabing our existing boiler draft fan steam turbines, which take steam off the desuperheaters of the boilers and let down across the turbines to drive the fans. We use all the steam that is let down from these turbines, so we will also need to supplement our existing usage with a steam let down/desuperheating station if we decide to change out all these to VFDs. A loss of plant electrical power would result in a total steam shutdown regardless of using steam driven or VFD driven equipment in our plant, just the way we are set up. The maintenance costs of overhauling the turbines is much higher than VFD's, and we are looking to standardize all the VFD's to be the same so a spare can be kept on the shelf in the event of failure. Turbine overhauls also take considerably longer than a VFD replacement, especially if spare equipment for the VFD is available on the shelf. Starting up from a dead stop is challenging, as we have old eddy current drive equipment to restart a boiler until enough steam has been generated to restart the turbines, and these drives are very unreliable. The operating costs of the VFDs are obviously higher, but for the reasons above we are leaning toward changing to all VFDs.
I wanted to make sure we aren't missing something with this potential change.
-Mike
I wanted to make sure we aren't missing something with this potential change.
-Mike