CAPACITANCE PROBE MEASUREMENT TECHNIQUE FOR LOCAL PARTICLE-VOLUME CONCENTRATION IN CIRCULATING FLUIDIZED-BED COMBUSTORS

This paper describes a capacitance probe measurement technique for the quantitative determination of local particle volume concentrations in side a fluidized bed combustor. The influence of temperature, water co ntent in the fluidization gas, and burning fuel particles in the solid s inventory on the measured signal is investigated in a la,oratory-sca le fluidized lied combustor. Application of the measurement system is demonstrated on a semi-technical scale circulating fluidized bed (CFB) sewage sludge combustor. Dy applying a data preprocessing step and a suitable calibration routine, the measurement system is able to quanti tatively measure local average solids volume concentration as low as 0 .1 vol.-%. Radial profiles of local average solid volume concentration s taken at various elevations inside the riser demonstrate the perform ance of the technique.