Splash and Disengagement Zone Heat Transfer in a Propane-Burning Fluidized Bed

Abstract

Experimental data on the heat transfer coefficients from a bubbling fluidized bed burner toward water-cooled confining walls placed above the free surface of the bed are scarce. The present work is an attempt to cover this gap. Experiments were carried out in a laboratory scale fluidized bed reactor that was equipped with a double pipe heat exchanger located above the bubbling bed region. The bed was composed of silica sand particles and five different sizes were tested—107.5, 142.5, 180, 282.5, and 357.5 μm. The bed operating temperature ranged from 700°C to 820°C. Under these circumstances, heat is transferred to the membrane walls through three mechanisms: convection from the gas–solid flow, radiation from the bed surface or from the flame, and projection of solid particles away from the bed toward the confining walls. A correlation for the global heat transfer coefficient is proposed with an average deviation of ± 20%.

Keywords:

• heat transfer
• membrane walls
• bubbling bed
• splash zone

ACKNOWLEDGMENT

The authors are thankful to the Portuguese Fundação para a Ciência e Tecnologia for the financial support for this work under the Research Project POCTI/EME/44300/2002.