Dust collection and converter off-gas ducts
Bag filter isolation, converter off-gas cycling and the purge arrangements that keep explosive gas out of the working area.
Dust collection ductwork on a steel plant is a network rather than a single line: many branches, each with a damper, all pulling towards a bag filter or an electrostatic precipitator. The dampers are small compared with the flue gates but there are dozens of them, and a stuck branch damper quietly ruins the balance of the whole system.
Branch dampers
These are usually square multi-blade or round butterfly units with a manual lever or a small electric actuator. Because they are used for balancing, the characteristic matters: opposed blades give a predictable area-to-angle relationship and let the commissioning engineer set a branch by angle rather than by guesswork. We mark the blade angle on the quadrant so the setting can be recorded and repeated.
Converter off-gas
Converter off-gas is intermittent and dirty, and it is explosive when carbon monoxide meets air. The duct dampers cycle with every heat, which on a busy converter means several hundred operations a week. These gates are built with hardened linkage, external bearings and nitrogen purged seals, and the actuator is sized for the duty cycle rather than the torque alone.
Keeping the working area safe
Where a damper isolates a duct that personnel may enter, the seal has to be verifiable. We fit a pressure tap on the downstream side of the seat so that a gauge can be connected before a permit is issued. That single tapping turns an assumption into a measurement.
Balancing records
We recommend that every branch damper position be recorded at commissioning and checked at each shutdown. The cost is a sheet of paper; the benefit is that a branch that has drifted is found before it affects product quality.
Talk to us about this duty
Send the duct section, design temperature, pressure difference and the duty point. We reply with the gate type, the material selection, the drive and a general arrangement drawing for approval.