By Yougen Kong, PhD, SOLVAir Products, Solvay Chemicals, Inc.
In this case study, two boiler units at Constellation Energy’s Wagner site burnt low sulfur coal. Trona was injected at the inlet of the air preheater, and test results showed that the targeted 30% and 50% removal rates for SO2 for both units were successfully met with reasonable trona federates. Around 10% additional NOx were also removed.
While results showed that trona could meet established removal rates when a higher SO2 removal rate was needed, it was clear that sodium bicarbonate would be the product of choice.
For Unit 2, around 90% of mercury was removed with trona injection alone. For Unit 3, only up to 80% of mercury was removed by PAC without trona. Over 90% Hg removal was realized by PAC with trona injection. The positive effect of sodium bicarbonate on Hg removal was also demonstrated and comparable to trona.