Effect of cold air stream injection on cyclone performance at high temperature

•Slits were created in wall of industrial high-temperature cyclone.•Cold stream was injected into cyclone through slits.•Cold stream injection reduced gas tangential velocity and separation efficiency.•Particle deposition on wall closely related to wall temperature distribution.•Cold stream injection effectively reduced particle deposition on wall.

A cold air stream was injected into a cyclone operating at a high temperature through slits created in the cylindrical part of the wall. The effects of the cold stream injection on the cyclone performance were investigated by experiment and CFD simulation. The particle deposition on the wall was observed to be closely related to the cyclone wall temperature distribution, with the particles mainly deposited on the high-temperature (>932 K) parts of the wall, and no particle deposition occurring on parts with temperatures lower than 873 K. However, the separation efficiency decreased with increasing flow rate ratio of the cold air stream. This was because the injection of the cold stream caused the bypassing of the hot stream through the vortex finder, thereby decreasing the tangential velocity of the hot gas. Hence, when particle deposition on the wall severely interferes with the operation of a cyclone, the injection of a cold stream can be used to significantly reduce the particle deposition, although this also decreases the separation efficiency and 50% cut size.

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