Sinter and coke oven gas ducts
Heavy dust, tar condensation and constant cycling. Why replaceable wear parts matter more than a thicker plate.
Sinter waste gas is the most abrasive duty we build for. The dust is coarse, it is delivered at speed, and it is wet enough to stick to any surface that is not swept. A gate on this duty is a wear item, and the only sensible design question is which parts wear and how quickly they can be changed.
Design for replacement
The blade carries a bolted 8 mm wear liner rather than being made thicker. The seat ring is a separate bolted component. Guides are replaceable inserts. All three can be changed in a shutdown with the duct in place, which is the difference between a two-day repair and a two-week one. We supply the first set of spares with the gate so the plant has them before they are needed.
Tar and naphthalene
Coke oven gas mains carry tar vapour that condenses below about 90 °C. The condensate coats the blade and the guide, and the gate slowly seizes. The countermeasures are to keep the duct above the condensation temperature, to fit a heated gland, and to cycle the gate on a schedule rather than waiting until it is needed in an emergency. A gate that is exercised monthly does not seize.
Explosion protection
Coke oven gas is explosive between roughly 5 % and 30 % in air. Seals are purged with nitrogen, and the purge pressure is monitored. The actuator is specified for the area classification and the local isolator is placed outside the hazardous zone. Limit switches are duplicated so the interlock does not rely on one device.
Position feedback
Sinter plant control rooms run the strand on interlocks that depend on damper position. We supply two independent position signals, one mechanical and one electrical, so a failed switch stops the gate being reported open when it is closed.
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.