Estimating the Gas and Dye Quantities for Modified Tracer Technique Measurements of Stream Reaeration Coefficients.

摘要

Measuring stream reaeration coefficients with a modified tracer technique has been accomplished by injecting ethylene or ethylene and propane together and a rhodamine-WT dye into the stream. The movement of the tracers through the stream reach is described by a one-dimensional diffusion equation. The peak concentrations of the tracers at the downstream end of the reach depend on the concentrations in the stream at the injection site,the longitudinal dispersion coefficient,the water velocity,the reach length,and the duration of the injection period. The downstream gas concentrations also depend on the gas desorption coefficients. The concentrations of the gases in the stream at the injection site depend on the gas flow rates through the injection diffusers,the efficiency of the absorption process,and the stream discharge. The concentration of dye in the stream at the injection site depends on the dye flow rate,the concentration of the dye solution,and the stream discharge. Equations for estimating the gas flow rates,the quantities of the gases,the dye concentration,and the quantity of dye together with procedures for determining the variables in these equations are presented.