A LOW COST METHOD FOR REDUCING MERCURY EMISSIONS IN FOSSIL-FUEL FIRED POWER PLANTS

RECENTLY, THERE HAS BEEN INCREASED ENVIRONMENTAL CONCERN ABOUT THE EMISSIONS OF MERCURY FROM COMBUSTION SOURCES IN THE FORM OF METAL FUMES OR SUBMICRON PARTICLES. NATURALLY OCCURRING MERCUTY IN A FUEL VAPORIZES DURING COMBUSTION AND THEN CONDENSES AS THE COMBUSTION GASES COOL, LEADING TO INTERESTING CHALLENGES IN THE DESIGN AND OPERATION OF EQUIPMENT TO CLEAN THE FLUE GASES PRIOR TO STACK RELEASE. STUDIES HAVE INDICATED THAT MERCURY EMISSIONS CAN BE REDUCED FROM COAL FIRED POWER PLANTS BY INJECTING ACTIVATED CARBON OR VARIOUS SORBENTS. THE DRAWBACK OF THESE TECHNOLOGIES IS THAT THEY REQUIRE CONSIDERABLE CAPITAL INVESTMENT IN EQUIPMENT AND MATERIAL. THE HYPOTHESIS THAT MERCURY EMISSIONS CAN BE CONTROLLED USING A LOW COST METHOD OF RECYCLING FLY ASH FROM AN AIR POLLUTION DEVICE BACK INTO THE FLUE GAS STREAM WITHOUT COMPROMISING THE PARTICULATE EMISSIONS OF THE SYSTEM WILL BE EXPLORED. THE APPROACH USED IS BASED ON BOTH MODEL/THEORETICAL AND EXPERIMENTAL TASKS. PROCESS MODELS AND A PILOT-SCALE COAL FIRED FACILITY WILL BE USED TO ANSWER THIS HYPOTHESIS IN PHASE I. MERCURY ADSORPTION BEHAVIOR WILL BE INVESTIGATED USING PULVERIZED COAL FLY ASH. THE OBJECTIVE IS TO IDENTIFY AND QUANTIFY WHETHER FLY ASH OBTAINED FROM AN AIR POLLUTION CONTROL DEVICE CAN BE RECYCLED INTO THE FLUE GAS STREAM TO CONTROL MERCURY EMISSIONS WITHOUT COMPROMISING OVERALL SYSTEM PERFORMANCE AND ECONOMICS. MORE SPECIFICALLY, THE KNOWLEDGE GENERATED IN PHASE I WILL BE USED TO (1) IDENTIFY HOW FLY ASH CAN BE USED MOST EFFECTIVELY TO CONTROL MERCURY EMISSIONS FROM PULVERIZED COAL BOILERS, AND (2) FURTHER DEFINE WHAT TESTS ARE NEEDED IN A PILOT/FIELD DEMONSTRATION FOR PHASE II.