Page 300 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

Chapter 10
Post-combustion Air Emission Control

10.1 Introduction

While some of the air emissions are greatly reduced by pre- and in- combustion
technologies, there are always various pollutants remain in the flue gas. Their
concentrations have to be further reduced to certain levels to meet local air emission
standards. Air emission control at this stage is referred to as post combustion
control in this book.
Post-combustion technologies include separation from the gas stream based on
the principles introduced in Part I. Sometimes it also involves phase change by
condensation of vapor to liquid followed by liquid-gas separation. Air emissions in
the flue gas or exhaust gas can also be transported from gas phase to liquid or solid
phase by sorption, or converted to less hazardous or benign species by incineration,
or catalytic conversion. Dilution by atmospheric air, which is also called air dis-
persion, is the last step, through which the air pollutants enter the atmosphere. Air
dispersion will be introduced shortly in the coming chapter.

10.2 Control of Particulate Matter Emissions

Cyclone, electrostatic precipitation, and filtration technologies are widely used for
post-combustion particulate matter emission control. Cyclone is primarily
employed as a precleaner or a fuel recycling device in a fluidized bed combustion
system. Electrostatic precipitation and filtration are two most widely commercial-
ized technologies for post-combustion PM emission control. Sometimes, water
spray tower can be used for sticky particulate removal too. Their engineering
designs are introduced as follows.

© Springer Science+Business Media Singapore 2014 277
Z. Tan, Air Pollution and Greenhouse Gases, Green Energy and Technology,
DOI 10.1007/978-981-287-212-8_10