American Petroleum Institute

MANUAL ON DISPOSAL OF REFINERY WASTES VOLUME ON ATMOSPHERIC EMISSIONS CHAPTER 6-DISPERSION OF GASES
 N PUBL 931 C6

Annotation

FOREWORD

This chapter describes environmental conditions at the probable site of refinery construction and the effects of these conditions on plume rise, atmospheric dispersions, and ground level concentrations. Meteorological aspects are discussed at some length. Ground level concentrations of pollutants should be determined from the most accurate existing predictive techniques prior to actual construction. This will ensure that specific requirements are not exceeded.

In evaluating plume rise and atmospheric dispersion, an eclectic approach is used. The result is one formula for the determination of plume rise and one set of formulas for the determination of ground level concentrations. For refineries located where abnormal conditions are not encountered, these equations represent a suitable tool for the design engineer to use in estimating ground level concentrations and thereby determining the required stack heights. (High-velocity vents are not covered by these equations.)

The predictive techniques presented herein are applicable to estimating atmospheric dispersion at a single source of emission over uncomplicated terrain, when mean wind speed and direction can be determined. The equations enable determination of ground level concentrations for an elevated source and for a ground level source. Predictive techniques for estimating atmospheric dispersions of emissions from multiple sources are also included. Dispersion coefficients are most applicable to ground level releases, but they have been applied to stack releases as well. Within the layer in which diffusion occurs, it is assumed that stability characteristics remain constant.

When designing a refinery facility, neither this approach nor any textbook approach is sufficient in cases of unusual atmospheric conditions or irregular topography. Handling these conditions requires a high degree of expertise and may involve the use of other predictive aids, such as wind tunnels