NIOSHTIC-2 Publications Search
Electrogasdynamic Application to Dust Monitoring.
Proc 2D Int'l Clean Air Congress Wash DC 12/6-11/70 Cp-19e 12/71 PP 432-436 :432-436
Fly ash emissions from powerplant stacks are not as easily detected or measured as smoke or gaseous pollutants. To meet this need, the Bureau of Mines, U.S. Department of the Interior, is developing an instrument based on electrogasdynamic (egd) principles to continuously measure and record the size distribution and mass flow rate of fly ash in stack gases. Such an instrument would have the advantage of continuous measurement over systems in which the fly ash is filtered, weighed, and analyzed on an intermittent basis. It would also have the advantage of size-determination capability of similar systems that can only determine the total mass flow rate. A study of egd reveals that a gas stream carrying unipolar ions or charged particles can gain energy from or impart energy to the charged bodies. Although an obvious application of this interaction is that of power generation, other uses are possible, for example, dust precipitators. A precipitator based on the egi principle is made up of three sections. The dust-laden gas stream first enters a high-velocity ionizing section where the dust particles take on a unipolar charge. The gas then passes through a dielectric diffusing section where the velocity is reduced to permit charged particle radial velocities of the same magnitude as the axial velocity. Finally, the stream enters a collecting section (metal) where the space charge of the particles causes them to move to the collector wall. Velocity of the gas is maintained low enough that reentrainment of the particles is minimal, and if the collector section is long e
Proc. 2D Int'l. Clean Air Congress, Wash., DC, 12/6-11/70, Cp-19e, 12/71, PP. 432-436
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division