Process challenges and evaluation of bed agglomeration in a circulating bed combustion system incinerating red water

Abstract

AbstractIT Corporation (IT) has prepared a conceptual design of a red water incinerator pilot plant. This system consisted of a circulating bed combustion (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, partial quench, baghouse, induced draft fan, and a stack.Red water, a waste stream from the manufacture of trinitrotoluene (TNT), contains between 15 and 30 percent solids, of which approximately 45 percent are sodium salts and 55 percent are sulfonated derivatives of TNT isomers. It was anticipated that treatment of red water in a circulating or fluid‐bed combustor would result in the buildup of molten sodium and its salts on the bed material. The molten sodium and its salt may cause bed particles to agglomerate and decrease fluidization, ultimately resulting in failure of the system.During the course of the design, several process challenges developed primarily due to the composition of the red water and its impact on the system components and optimization of process parameters. Of all the process concerns encountered during the process design of the CBC pilot plant, the challenges that most concerned the author are the role of sodium salts in agglomeration and defluidization at operating temperatures and high levels of nitrogen oxides/sulfur oxides (NOx/SOx) emissions associated with circulating or fluid‐bed incinerator of red water.An initial treatability study utilizing a bench‐scale, 10‐centimeter (4‐inch) diameter fluid‐bed system that approximately simulates a CBC was conducted at Hazen Research in Golden, Colorado. Due to the nonavailability of the actual red water, a surrogate red water solution containing 15 percent dissolved solids was used during the 2‐day testing. The study focused on the role of the salts in agglomeration and defluidization associated with fluid‐bed incineration of red water.This paper discusses the process challenges faced during the conceptual design of the pilot‐scale system and the results 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 learned from bench‐scale testing.