Refractories that will optimize your riser duct

The riser ducts recycle heated air from lower cyclone stages and within the kiln itself, thus improving thermal efficiency and reducing fuel costs.

Riser ducts often have build-up problems. In the lower, hotter part of the cyclone system, chemical influences are the cause, and can affect both straight and curved duct sections. Higher up, build-ups are usually caused by a venturi effect, occurring mostly in the curved section of the duct.

The closer the duct is to the ’hot’ end of the cyclone system, the greater the risk of alkali penetration and refractory spalling. Where alkalis have penetrated (which they do to a depth of 20-30 mm), the refractory can expand 10 times more than normal, causing spalling. If this process is allowed to continue, the wall can collapse. To keep alkaline vapor from condensing, reduce the amount of insulation used.