Flow control by perforated plates using a blanking technique in wide-angle diffusers employed in practical electrostatic precipitator systems

The degree of flow uniformity through the treatment zone affects the collecting efficiency of electrostatic precipitators. The process of generating a uniform velocity distribution must take place before the flow reaches the collection chamber. This is achieved by a wide-angle screened diffuser upstream of the treatment zone. Owing to factors arising during fabrication, the performance of even well designed perforated plate-diffuser combinations can be deficient in practice. Under such conditions, uniformity of flow can be regained by applying local blanking of the perforated plate wherever high velocities are found. This paper studies the application of three perforated plates with the diffuser to control the velocity profile. Furthermore, it investigates the use of blanking techniques to modify the local porosity of the final plate. The characteristics of the flow were studied in detail by a five-hole Pitot tube in conjection with a microcomputer. © 1991.Royal SocietyB. ~ahin would like to thank the Scientific and Technical Research Council of Turkey (TUBITAK), and The Royal Society, U.K., for a study visit award in the European Science Exchange Programme