Novel Centrifuges for High Temperature Gas Cleaning

A design for a novel technique for separating submicron particles from an exhaust stream of a diesel engine has been developed at Cardiff. It consists of three main sections, an inlet where the exhaust gases are introduced, a rotating cylinder with a speed of 60,000 rpm or more and a two part outlet system, one to remove the particulate laden gas centrifuged out in the cylinder and one to remove the clean gas. The clean gas constitutes up to 90% of the flowrate.The development has involved the use of FLUENT (a well known finite difference modelling package, solving the approximations to the governing equations) for aerodynamic and particle dynamic predictions. This paper will show a series of predictions including particle tracking of particles 0.2 µm in size and contours of predicted velocities. Much of the development programme has been involved with the bearing system and minimisation of main shaft orbit to prevent bearing damage. Further development of the bearing system to allow higher speeds to be attained will yield greater separative performance. The existing prototype will separate particles down to less than 0.5µm.