Patent ID: 8461852

Claim:
A method for producing particle density map images of fluidised particles by electrical capacitance tomography in a fluidised bed apparatus, the fluidised bed apparatus comprising a gas distributor plate and one or more side walls defining a fluidisation space, and an electrical capacitance tomography sensor array positioned around the one or more side walls, wherein a first phase corresponding to fluidised particles having a first permittivity and a second phase corresponding to a fluidisation gas having a second permittivity are imaged, characterised in that the first permittivity used in calculating images is recalibrated during fluidisation of the particles to allow for changes in its permittivity value by using one or more recalibration capacitances measured by one or more pairs of reference electrodes positioned to measure the capacitance of densely fluidised particles near the one or more side walls.