Conventional and Alternative Power Generation

7Pollution Dispersal

7.1 Overview

Nothing is perfect and no ‘end of pipe’ pollution arrestor is 100% effective in cleaning up a polluted air stream. Something is always released. What is important is the concentration exposure of the environment to the emission upon release.

The most common (and usually the cheapest) way of quickly reducing the concentration of a discharge to the atmosphere is to release the emission via a tall chimney, stack or flue and use the atmosphere's turbulent mixing effect to disperse and dilute the pollutant.

National and internationally agreed environmental regulations and targets will dictate the parameters of the flue design (for example, flue height) and operation, perhaps enforcing these by ground‐level environmental monitoring.

This chapter will provide an introduction to the characteristics of the atmosphere and go on to describe the part it plays in environmental dilution and in modelling the release of emissions from stacks.

Learning Outcomes

• To be familiar with the atmosphere's structure and composition.
• To understand the theoretical atmospheric pressure/temperature relationship.
• To gain an understanding of temperature–elevation or lapse rates in the atmosphere and their effect on vertical motion.
• To be familiar with atmospheric stability classifications and their effect on point source emission physical behaviour.
• To be able to use simple dispersal modelling to predict emission concentrations downwind of a single point source.
• To be familiar with ...