PROCESS CHALLENGES AND EVALUATION OF BED AGGLOMERATION IN A CIRCULATING BED COMBUSTION SYSTEM INCINERATING RED WATER

IT Corporation (IT) has prepared a conceptual design of a red water in cinerator pilot plant. This system consisted of a circulating bed comb ustion (CBC) system with a capacity of 5.4 liters per minute (L/M) (1. 5 gallons per minute [gpm]) of red water followed by a hot cyclone, pa rtial quench, baghouse, induced draft fan, and a stack. Red water a wa ste stream from the manufacture of trinitrotoluene (TNT), contains bet ween 15 and 30 percent solids, of which approximately 45 percent are s odium salts and 55 percent are sulfonated derivatives of TNT isomers. It was anticipated that treatment of red water in a circulating or flu id-bed combustor would result in the buildup of molten sodium and its salts on the bed material. The molten sodium and ifs salt may cause be d particles to agglomerate and decrease fluidization, ultimately resul ting in failure of the system. During the course of the design, severa l process challenges developed primarily due to the composition of the red water and its impact on the system components and optimation of p rocess parameters. Of all the process concerns encountered during the process design of the CBC pilot plant, the challenges that most concer ned the author are the role of sodium salts in agglomeration and deflu idization at operating temperatures and high levels of nitrogen oxides /sulfur oxides (NOx/SOx) emissions associated with circulating or flui d-bed incinerator of red water. An initial treatability study utilizin g a bench-scale, 10-centimeter (4-inch) diameter fluid-bed system that approximately simulates a CBC was conducted at Hazen Research in Gold en, Colorado. Due to the nonavailability of the actual red water, a su rrogate red water solution containing 15 percent dissolved solids was used during the 2-day testing. The study focused on the role of the sa lts in agglomeration and defluidization associated with fluid-bed inci neration of red water. This paper discusses the process challenges fac ed during the conceptual design of the pilot-scale system and the resu lts of the bench-scale testing. Also presented are potential solutions and recommended tests and analyses for the pilot plant tests based on experience during the design of pilot-scale system and the lessons le arned from bench-scale testing.