Mercury control using moderate-temperature dissociation of halogen compounds

A method of removing mercury from a flue gas stream of a coal combustion system having a combustor and a pollutant control device, the method comprising:

• generating a dissociated halogen gas from a reactive precursor at a temperature in the range of about 60° C.-400° C., by providing activation energy to the reactive precursor;
• introducing the dissociated halogen gas to the flue gas stream to allow the dissociated halogen gas to react with mercury present in the flue gas stream at a temperature in the range of about 60° C.-400° C., the dissociated halogen gas introduced at least one location to the flue gas stream downstream from the combustor and upstream of the pollutant control device;
• injecting particulates into the flue gas stream, the particulates comprised of at least one of activated carbon, alkaline compounds (CaO, CaSiO3), or any combination thereof;
• and capturing the mercury using the pollutant control device.

A mercury control system for a coal combustion system comprising:

• a coal combustor;
• a pollutant control device comprising a particulate control device including at least one of an electrostatic precipitator, a fabric filter, and a scrubber;
• a halogen dissociation unit having an activation energy source for generating a dissociated halogen gas therein, the halogen dissociation unit in communication with a flue gas stream of the coal combustion system located downstream of the coal combustor, the halogen dissociation unit configured to expose the dissociated halogen gas to mercury present in the flue gas stream allowing the dissociated halogen gas to react with the mercury at a temperature in the range of about 60° C.-400° C. for capture by the pollutant control device;
• and
• a device for injecting carbon particulates.