Abstract
This paper describes a capacitance probe measurement technique for the quantitative determination of local particle volume concentrations inside a fluidized bed combustor. The influence of temperature, water content in the fluidization gas, and burning fuel particles in the solids inventory on the measured signal is investigated in a laboratory-scale fluidized bed combustor. Application of the measurement system is demonstrated on a semi-technical scale circulating fluidized bed (CFB) sewage sludge combustor. By applying a data preprocessing step and a suitable calibration routine, the measurement system is able to quantitatively measure local average solids volume concentration as low as 0.1 vol.-%. Radial profiles of local average solid volume concentrations taken at various elevations inside the riser demonstrate the performance of the technique.
