Limestone Injection is one of many technologies in the
Clean Coal Technologies program, it is one of the environmental control techologies which would also include
wet multicyclones, and
electrostatic precipitators. The
limestone injection process, is one of the combustion type processes, it uses a
Limestone Injection Multistage Burner (LIMB) to remove sulfur from coal during the
combustion cycle.
In the limestone injection process, the crushed
coal and limestone are suspeneded in a
boiler by an upward stream of hot air; the coal is burned in this bubbling fluidized mixture. The
sulfur from combustion gases combine with the limestone to form a solid compound, rather than being released into the atmosphere. The sulfur reduction can be achined with either
dry limestone or
hydrated lime, however hydrated lime is much more expensive. Limestone injection techonology is currently being developed aimed at
mercury control and capture, during the coal burning process; benefits will include low
capital cost, low
feed rates, and low
operating cost.