DETERMINATION OF VIABLE PROCESSES FOR REMOVING MERCURY FROM THE FLUIDIZED BED CALCINER (NWCF) OFFGAS SYSTEM AT THE IDAHO NATIONAL ENGINEERING AND ENVIRONMENTAL LABORATORY (INEEL)

摘要

Technologies were investigated to determine viable processes for removing mercury from the fluidized bed calciner (NWCF) offgas system at the Idaho National Engineering and Environmental Laboratory (INEEL). Technologies for gas phase and aqueous phase treatment were evaluated. Currently, mercury accumulation in the calciner off-gas quench system, containing most of the mercury, is transferred to the tank farm. These transfers lead to accumulation in the liquid heels of the tanks. The principal objective of aqueous phase mercury removal is tank heel mercury reduction. The system presents a challenge to traditional methods because of the presence of nitrogen oxides in the gas phase and high nitric acid in the aqueous scrubbing solution. Previous studies for removing mercury from the quench recycle indicate that few effective technologies are available because of the composition of this stream and functional requirements. The selected aqueous phase process is electrochemical reduction. The gas phase also presents a challenge as it contains large amounts of nitrogen oxides that may interfere with gas phase adsorption via activated carbon. Therefore, absorption (wet scrubbing) was selected for testing and evaluation. This work was done to compare a full MACT compliance design with a smaller, less costly design not intended to meet all of the MACT emission standards.