• Patent

Device for focussing particles suspended in a gas stream

A device for controlling the motion of particles suspended in agas stream is provided, including a pipe, through which at least afraction of the gas stream flows, a source of AC voltage, a sourceof DC voltage, and a plurality of electrode sets positioned withinthe pipe in series, generating an inhomogeneous electric field tocause the particles suspended in the gas stream to concentrate intoa narrow axial region in the center of the pipe. Each electrode setincludes a first pair of opposed hyperboloidally shaped electrodesconnected to the AC voltage source and a second pair of opposedhyperboloidally shaped electrodes connected to the DC voltage. Thefirst and second pairs of opposed electrodes are positioned atspaced apart intervals around the circumference of the pipe todefine an opening through which at least a fraction of the gasstream flows. The electrode sets are positioned within the pipe inseries such that the gas stream flows through the openings definedby each successive electrode set. The spaced apart distance betweenthe electrodes of each successive electrode set is decreased toreduce the size of the openings, causing the particles suspended inthe gas stream to focus or concentrate along successively narroweraxial regions in the center of the pipe.


Periasamy, R., Ensor, D., & Donovan, R. P. (1995). IPC No. U.S.Device for focussing particles suspended in a gas stream (Patent No. 5439513.)