A novel carbon-based process for flue gas cleanup

Abstract

The objective of this project is to demonstrate the preliminary technical and economic feasibility of a novel carbon-based process for removal of at least 95% SO{sub 2} and at least 75% NO{sub x} from coal combustion flue gas. In the process, flue gas leaving the electrostatic precipitator (ESP) is passed through a trickle bed of activated carbon catalyst employing a periodic flush of low strength sulfuric acid. The SO{sub 2} is oxidized to SO{sub 3} and removed as medium strength sulfuric acid. The SO{sub 2}-free flue gas is then mixed with NH{sub 3}, and the NO{sub x} in the gas is subjected to selective catalytic reduction (SCR) to N{sub 2} over a fixed bed of activated carbon catalyst. In the previous three quarters, a detailed project management plan was prepared describing the experimental setup, work plan, and test plan. The experimental system was completed for SO{sub 2} conversion at Waterloo and for NO{sub x} conversion at RTI. Shakedown experiments were completed. In the present quarter, the NO{sub x} removal performance of two additional modified carbon catalysts (MCCII and MCCIII) was studied. MCCII showed NO{sub x} removal efficiency which was similar to that observed for MCCI. However, MCCI was considerably less active for NO{sub x} removal. SO{sub 2} removal experiments with NO present in the feed gas were performed with MCCI. SO{sub 2} removal efficiency was consistently about 98% over each of 10 cycles and was very similar to that observed earlier with no NO present in the feed. Finally, a preliminary economic evaluation of the process was performed and a project review meeting was held. The economic evaluation showed that the Rn-Waterloo process was competitive with SCR/IFGD and other combined SO{sub 2}/NO{sub x}, removal processes.