Page 251 - Air pollution and greenhouse gases from basic concepts to engineering applications for air emission control

Chapter 8
Pre-combustion Air Emission Control

Air emission control is enforced when the ambient air quality or the source air
emission rate does not meet certain standards. There are three basic approaches to
air emission control: pre-, in-, and post- combustion air emission control. The most
cost-effective is to control before combustion, which reduces the load of down-
stream units. The last choice is add-on devices for flue gas cleaning. These extra
devices contribute significantly to the capital and operating costs of the plant; they
also reduce to some degree the thermal efficiency, because the devices may also
reduce some of the power output of the plant. Many of these devices also produce
another form of waste, usually solid or liquid being discharged to the environment.
This chapter is focused on the following pre-combustion air emission control
technologies.

• Fuel cleaning,
• Fuel substitution,
• Fuel conversion, and
• Alternative energy resources.

8.1 Fuel Cleaning

8.1.1 Coal Cleaning

One of the most cost-effective approaches to the control of air emissions is the
removal of the unwanted chemicals from the fuels before combustion.
Two most common engineering practice examples are coal washing, and oil and
gas refinery. In the United States, about 50 % of all coals supplied to power plants are
washed before delivery. In Germany, almost all coals are washed before firing. The
oils and gases are refined globally following the specific government regulations.
Fuel cleaning is the most effective way to reduce the contents of sulfur, ash-forming

© Springer Science+Business Media Singapore 2014 227
Z. Tan, Air Pollution and Greenhouse Gases, Green Energy and Technology,
DOI 10.1007/978-981-287-212-8_8