ABSTRACT
This chapter is concerned with the practical removal of air pollutants through the mechanism of downward gravitational forces. Gravity settling chambers are the oldest and simplest means of removing large diameter suspended particles from a gas. High-efficiency settling chambers are often fitted with baffles or deflectors to change the gas flow direction. In specifying settling chamber dimensions, gas flow velocities must be maintained below the reentrainment velocity of deposited particulate. Dry-type primary collectors such as settling chambers, low-pressure-drop cyclones, high- efficiency centrifugals, and dynamic precipitator devices are among the most common and important devices to the environmental engineer. The vertical flow systems are basically elutriators that remove only those particulates whose settling velocities are greater than the linear gas velocity. Although settling chambers are limited in collection efficiency, they have the distinct advantages of low cost, simple construction, no appreciable pressure loss, no problems with abrasive grit handling, and they offer a means of dry disposal of particulate wastes.
