Analysis of Residence Time Distributions of Different Solid Biomass Fuels by using Radio Frequency Identification (RFID)

摘要

The residence time distributions of different typical solid biomass fuels such as wood pellets, wood chips, and wood cubes are measured on a scaled model of a forward-acting grate in continuous operation by using radio frequency identification (RFID). A variation of motion patterns, grate operational conditions, and bed material is performed. Based on the residence time distributions, diffusion coefficients are derived, which are a measure for mixing on the grate and are of importance as input parameters of fuel-bed models in CFD simulations of grate-firing systems. RFID measurements have the advantage to be capable of tracking multiple particles without requiring visual contact. Residence time distributions are obtained without any artifacts introduced by the feeding equipment or manual charging. It is found that the diffusion coefficients obtained are in agreement with the results of other measurements performed in literature. The diffusion coefficients increase with enhanced stroke length and stroke velocity as well as with decreasing bed layer thickness and particle sizes. Particle shape has a strong influence on longitudinal mixing and the diffusion coefficients.