Among all the fossil fuels used for power generation, coal requires the most extensive infrastructure for processing, handling, storage, loading and unloading operations (all these facilities generate important environmental impacts). Coal firing requires the use of crushers, pulverizers, ash handling equipment, soot blowers, and dust and emissions control equipment.
The most widely used particle controls used for coal combustion are multiple cyclones, electrostatic precipitators, fabric filters and Venturi scrubbers. Various techniques are employed to reduce SO2 emissions from coal-fired plants: physical coal cleaning, chemical coal cleaning, switching to lower-sulfur coals and flue gas desulfurization.
Some methods for controlling nitrogen oxides are reducing the peak temperatures in the combustion zone or the gas residence time in the high-temperature zone, the installation of low-NOX burners, selective catalytic reduction, and selective non-catalytic reduction.
At some plants in Canada and the United States, devices are used to inject activated carbon or add sorbent to coal specifically to control mercury emissions.
Other methods, such as flue gas desulfurization and particulate control, also help to reduce mercury emissions. It has been reported that mercury emissions reductions of 29%, 39% and 45% can be obtained from electrostatic precipitators, baghouses and flue gas desulfurization, respectively [45, 46, 48, 50].