Experimental study on particle characteristics in an opposed multi-burner gasifier

• Particle behaviors in gasifier under hot condition are observed for the first time.
• Particle characteristics are studied by multiplicate visualization techniques.
• The particles in gasifier are mainly classified to five different types.
• Larger size particles exist as particle groups with three different types.

Based on the bench-scale opposed multi-burner (OMB) coal-water slurry (CWS) gasifier, temperature distributions of particles at different spatial regions, reactivity characteristics of particles and their interactions were studied with a variety of visualization techniques. The particles in gasifier are mainly classified to five types, and the principles of transformation between them are concluded as: low temperature particle without wake (LTP) could transform to low temperature particle with high temperature wake (LTP-HTW) when contacted with high temperature flame, then transform to LTP as reactions terminate and the particles become non-reactive; low temperature particle with low temperature wake (LTP-LTW) would transform to LTP-HTW when transfer to high temperature regions; as LTP-HTW adhere to the refractory wall, their wakes vanish and particles transform to high temperature particle without wake (HTP); high temperature particle with high temperature wake (HTP-HTW) could finally transform to HTP after the end of reactions. Particle groups with irregular shapes, flake-shaped and hollowed spherical structure are the forms of existence for larger size particles in gasifier.