This paper presents results obtained in the designing of a heating device, which utilized eddy current induced by rotating permanent magnets. The finite-element method, by using overlap grid coordinate system, is used for the eddy-current analyses. In order to solve eddy-current problems that consist of several conductive objects, which are moving in magnetic field, we have to remesh the region under consideration according to those positions, in the step-by-step computation. To reduce the computation time, a composite mesh scheme is introduced into such eddy-current problems. The heat conduction analysis is also carried out after calculating the eddy-current distributions. The results show that the device is very useful to dry powders and grains.