An experimental comparison of the airflow characteristics of four-walls tangential firing and four-corners tangential firing

• The four-walls tangential firing is a new kind of tangential firing method.
• We study the airflow characteristics through particle tracer and PDA test.
• We compare the airflow characteristics of FWT with those of traditional FCT.
• For FWT, the jets’ rigidity at low part is affected by the adjacent upstream jets.
• The airflow velocities close to the wall of FWT are high.

A new kind of tangential firing—four-walls tangential firing (FWT)—has been gradually adopted in large utility boilers, particularly supercritical boilers. It is necessary to determine the airflow characteristics of this new method. In this study, we use a cold modeling experimental device in laboratory based on the prototype of one 660 MW power supercritical boiler with FWT. From results of particle tracing and particle dynamic analyzer measurements, we study the airflow characteristics in the furnace. We also compare the observed airflow characteristics with those of traditional four-corners tangential firing (FCT). We are able to discern differences in airflow characteristics between FWT and FCT. We find that for FWT, the rigidity of the jets is not only influenced by the rotating airflows, but also by the adjacent upstream jets. Furthermore, the airflow velocities close to the wall of FWT are significantly higher than those of FCT and the directions of the airflow are almost all oriented toward the wall.