EVOLUTION OF PARTICLES IN THE PLUMES OF COAL-FIRED POWER-PLANTS .1. DEDUCTIONS FROM FIELD-MEASUREMENTS

A series of detailed airborne measurements are presented of particle size distributions and gas-toparticle (g-to-p) conversion rates at various locations in the plumes from two large coal-fired, electric power plants, situated in quite different geographical regions (Washington State and New Mexico). The particles in the plumes generally fell in three distinct size ranges characterized by geometric mean volume diameters between 0.001-0.2μm (mode 1), 0.11-0.55μm (mode 2), and 0.55-4.4 μm (mode 3). All three modes played important roles in the coagulation of particles in the plumes which, in turn, affected the particle size distributions. The concentrations of particles sometimes decreased with travel time in the centers of the plumes while increasing at the edges of the plume. In many cases, the concentrations of particles of a certain size were less in certain regions of the plume than in the ambient air. G-to-p conversion rates, which were measured by three techniques, were on the order of a few tenths of one per cent of SO2 h-1 for the Washington plant and a few per cent of SO2 h-1 for the New Mexico plant. These observations are interpreted, in the light of a numerical model of plumes, in Part II of this study. © 1979.