Process and system to reduce mercury emission

A method to decrease emissions of nitrogen oxide and mercury while decreasing carbon in fly ash, comprising:

• selecting a combination of factors from the group consisting of fuel type, fuel staging, air staging and a combustion condition to control a combustion process to generate a flue gas comprising fly ash with enhanced unburned carbon;
• controlling the combustion process according to the factors to produce the flue gas comprising fly ash with enhanced unburned carbon, NOx and vaporized mercury;
• removing NOx from the flue gas;
• allowing the flue gas to cool to a lower temperature to collect fly ash with absorbed mercury;
• passing the fly ash with absorbed mercury through an ash burnout unit to remove carbon from the fly ash and to produce a mercury-containing exhaust gas;
• and
• passing the mercury-containing exhaust gas through a collection unit to capture the mercury.

A system to decrease emission of mercury;

• comprising:
• a combustion zone that is controlled to generate a flue gas comprising fly ash with enhanced unburned carbon and that produces vaporized mercury;
• and
• a post combustion zone to cool the flue gas to collect fly ash with enhanced unburned carbon with absorbed mercury.

A system to decrease emissions of nitrogen oxide and mercury while decreasing carbon in fly ash, comprising:

• a combustion zone that is controlled by fuel type, fuel staging, air staging or a combustion condition to generate a flue gas comprising fly ash with enhanced unburned carbon and that produces vaporized mercury;
• a post combustion zone to cool the flue gas to collect fly ash with enhanced unburned carbon with absorbed mercury;
• an ash treatment unit that removes carbon from the fly ash and produces a mercury-containing exhaust gas;
• and
• a collection unit that captures the mercury.