Lidar study of the keystone stack plume

Abstract

A lidar study of the dispersion of the effluent from the tall (245-m) stacks of Keystone Generating Station in western Pennsylvania was conducted with the aid of two field experiments in May and October 1968. The observations, which were mostly obtained during stable conditions in the morning hours, reveal in detail the important plume characteristics that must be included in a realistic diffusion model for plumes from tall stacks: 1. (1) fanning and tilting due to wind veering with height. 2. (2) fumigation, which brings high concentrations to ground level in a pattern which, because of the tilting, progresses with time from the left to the right of the plume looking downwind. 3. (3) plume trapping by elevated stable layers. A comparison between the predictions of the Briggs/ASME plume rise formula and the lidar observations for 17 cases when temperature profiles were available gave a mean absolute difference of 30 m. A secondary experiment involving two sets of lidar plume measurements when the electrostatic precipitators at the power plant were all and half in operation, furnished estimates of 86 and 97 per cent for the precipitator efficiency on two separate days, compared with the rated value of 99 per cent. To investigate the potential of lidar for making quantitative measurements, a sample attenuation-corrected cross section of absolute mass concentration was computed on the basis of Mie scattering theory and independent particle size measurements. The integrated mass per unit plume length represented by this cross section was 680 gm −1, compared to 875 g m −1 calculated from the power-plant data and wind speed.