Operating Results from Supercritical Water Oxidation Plants

Abstract

Two supercritical water oxidation (SCWO) plants that utilize transpiring wall reactor designs for processing organic wastes are undergoing testing and operation. One plant is designed to destroy Navy excess hazardous materials (EHM). The EHMs represent organic materials found aboard Navy ships. The plant has a nominal waste feed rate of 45 kg/h and utilizes compressed air as the oxidant. Corrosive wastes, including chlorinated solvents (diluted with kerosene) and lube oils, and a salt-producing photographic solution simulant have been processed at feed rates between 45 and 95 kg/h. Tests have been conducted at an operating pressure of 24.1 MPa and reactor temperatures between 594 and 816 °C. Destruction removal efficiencies of better than 99.99% have been obtained. Priority air pollutants NOX and CO are below 25 and 100 ppm, respectively. Liquid effluent total organic carbon (TOC) levels are consistently below 3.5 ppm. Post-test inspections have not revealed any obvious reactor liner corrosion or salt deposition. A second SCWO plant designed for the destruction of obsolete, colored smokes/dyes and pyrotechnic munitions has been fully commissioned and is currently undergoing validation testing. The plant is designed to process 145 kg/h of a 25 wt % basis slurry of smokes and dyes. The plant uses oxygen as the process oxidant. The reactor operating pressure is 26.3 MPa, and operating temperatures are between 575 and 750 °C. Off-site plant skid fabrication was completed in 1997, site preparation and construction were completed in 1998, and commissioning was completed in 1999. Validation testing will be completed in the fourth quarter of 2000. Production demilitarization processing of smokes and dyes will follow.