NIS-CO FANS AND BLOWERS

In
pactice this sulfur removal process requires a gas-tight, zero leakage,
high temperature and high pressure blower for intermittent duty that
must handle toxic gases and must be capable of being brought on line
immediately upon demand. To do this the following features on the
blower must be provided:
- Double welded casing
construction;
- Steam flows between the
housing walls to maintain a constant 285 F gas temperature inside the
fan (because below 285 F sulfur will change from a gaseous to a solid
state and will "freeze" to the blower surfaces causing damage or
destruction);
- A mechanical shaft seal with
heat tracing and purge by air or nitrogen;
- To assure tight tolerances
between the shaft and shaft seal, the housing should be supported at
the centerline, and grows concentric to the fan shaft when exposed to
heat.: since this support isolates housing from the drive and mounting
bases, housing thermal growth doesn't cause forces to be applied to
these bases.
- To prevent the shaft from
taking a permanent set when the blower is idle but still exposed to the
high temperature, a turning gear is provided to keep the blower
rotating at a very slow speed of 25 - 40 RPM; alternatively a VFD speed
control can be used