A method for the estimation of image distortion which can occur in the reconstruction of electrical capacitance tomography (ECT) data for pneumatic conveying process is presented. Image distortion is associated the finite sampling rate of tomographic instrumentation which arises from changes in the distribution of phases occurring during a measurement cycle. The method uses an algorithm which provides the solution of the inverse and forward problems for an idealized 2-D sensor and to visualize the movement of powder slugs. The influence of the geometry of the sensor electrodes and the nature of slug perturbation on the fidelity of the reconstructed image is discussed. The practical implications of the simulation for the application of capacitance tomography for monitoring and control of dense phase conveying are discussed.