Section 4 - Air and gas filtration and cleaning

Abstract

This chapter focuses on the processes of air and gas filtrations and their applications in microfiltration and the food industry. Compressed air is used as a motive force for the transport of materials, as a carrier medium for energy to a point of use where it acts as a driving force for pneumatic equipment, as a substrate in many industries, and as a processing medium in mixing, packaging and pressurizing. The very production of this compressed air however causes many impurities and contamination in the gas. The extent of treatment required for air from a compression system depends largely on the application. General industrial applications utilizing mains compressed air supplies may simply require partial water removal, by aftercooling, followed by filtration to remove solid contaminants above a certain size. Air quality specifications may dictate high purity requiring several stages of filtration, drying and oil removal. There are several industrial sectors where sterile compressed air and other gases is essential. A system for the sterilization of compressed air (or gas) must remove permanently all micro-organisms potentially dangerous to the process, be reliable over long operating periods, and should be economic to install and maintain. There are other alternative methods to achieve sterile air, which includes dry heating in an oven at a temperature of at least 165°C for 2 hours; irradiation by using high intensity ultraviolet, X-ray or gamma ray sources; and physical filtration.