Aerodynamic considerations in electrostatic precipitation.

The paper reviews electrostatic precipitator theory from the standpoint that the ideal theory should preserve the basic simplicity of the Deutsch law, yet embody all the processes taking place in a physically sensible way. It argues that the performance of a precipitator is normally dominated by aerodynamic processes, and concludes that a proper rigorous treatment of particle transport in the turbulent flowing gas cannot give the sought-after simplicity. An alternative approach is suggested which incorporates the concept of a gas treatment time distribution function with the basic exponential form of the original Deutsch equation. This approach satisfactorily predicts the effects of gas turbulence on precipitator performance, and can be extended to allow examination of the effects of shielded collecting electrodes. It could, if required, be extended further to account for large-scale gas maldistribution.

From the precipitator designer’s point of view, it is recognised that the purely theoretical approach to determining the gas treatment time distribution function is unlikely to yield satisfactory results. But the paper suggests how this function could be obtained in numerical form from simple model experiments. Before too much is claimed for the ideas contained in the paper, the need for experimental verification is stressed. Such experiments are in progress.