Heat Transfer and Fluidization Characteristics of Lignite in a Pulsation-Assisted Fluidized Bed

Abstract

To address the problem of low drying efficiency increasing lignite dryer size, a pulsation-assisted fluidized bed with horizontal tube bundles was built for investigating the heat transfer in lignite particles with the goal of enhancing the lignite drying rate by introducing a pulsed flow to increase the heat transfer rate. Results showed that the pulsation-assisted flow increased the heat transfer rates by a maximum of 50–100%. The heat-enhancement effect increased as the gas velocity increased, with 3 and 5 Hz pulsation-assisted flows demonstrating higher heat transfer rates than a 1 Hz flow. Local heat transfer rates showed a maximum value at the tube top for lignite. Simulation was conducted to analyze the details of the lignite particles and bubble movements to explain the heat transfer rate enhancement effect.