Carbon Adsorber Fouling: Removal of Ammonium Bisulfate

Infilco Degremont’s efficient sludge treatment process using a High Temperature Fluidized Bed (HTFB) incinerator is used by several waste processing plants in the United States and Canada. In a few instances, a buildup of ammonium bisulfate within the activated carbon bed absorbers has become an issue. The carbon bed absorbers are used for the removal of mercury from the incinerator flue gas. Buildup of this compound on the carbon surface results in increases in the pressure drop across the adsorber, as well as decreases in the efficiency of the unit. This eventually leads to the need to shutdown the afflicted train in order to clean the absorbers and replace the activated carbon. Based upon literature research, it is believed that sulfuric acid aerosols in the system reacts with ammonia entering the gas stream from the scrubber service water to form ammonium bisulfate. In order to reduce the production of ammonium bisulfate aerosols within the gas stream, a caustic scrubbing system will be added to the system to neutralize acidic sulfur oxide species present in the waste gas. Process information provided by Infilco was used to develop a process simulation through AspenTech. Using this simulation, recommendations for the rate of sodium hydroxide addition in the gas scrubber were made. Furthermore, the change in aerosol formation due to the reduction in sulfuric acid was estimated.https://scholarscompass.vcu.edu/capstone/1013/thumbnail.jp