PRESSURE PROFILE IN A BENCH-SCALE CIRCULATING FLUIDIZED BED SYSTEM WITH MULTI-COMPONENT SOLID MIXTURES

摘要

This work analyzes the static pressure drop behavior in main components of a bench-scale circulating fluidized bed (CFB) when ternary mixtures of solids are fluidized at cold conditions.The CFB loop, which is composed by a 0.078 m internal diameter and 2.7 m height riser, a tangential cyclone, a 0.053 m internal diameter standpipe and a L-type valve for solids recirculation was fed with mixtures of fuel particles (saw dust and coal) and quartz sand.The experimental program followed a 22 factorial design with duplicated runs, in which the total solids inventory varied from 3.5 to 5.0 kg, and the mixture fraction (mass of fuel particles/mass of fuel particles and sand) from 0.025 to 0.05.In tests, the fluidizing gas velocity was 4.0 m/s and the proportion of coal to biomass was 1∶1.From results for total solids inventory of 5.0 kg was verified that the higher the mixture fraction (more bed volume) the higher the pressure drop in all components because of the wall friction increases.This effect was less critical for total solids inventory of 3.5 kg, but also significant at 95％ of confidence level.A semi empirical mathematical model was proposed for simulating the pressure drops across the system and comparing them with experimental data.