Study on the resource utilization of high fluorine-containing organic waste through fluidized incineration

Abstract

In this study, the method of fluidized incineration and water washing to recover hydrogen fluoride (HF) was proposed to dispose of high fluorine-containing organic waste. The resource utilization of the waste was investigated in a fluidized bed incinerator with a disposal capability of 10 t/d. The evolution characteristics of fluorine, operation conditions of the incineration system, absorption coefficient for HF by water washing, and HF corrosion during combustion were assessed. The results showed that HF and fluorocarbons were detected as the initial gaseous fluorides released during combustion. The release of HF could be divided into three stages, in which HF was generated from the volatilization of HF in the waste and the hydrolysis of fluorine in water-soluble salts (60–220 °C), oxidative decomposition of fluorinated organic components and residual carbon (220–800 °C), and hydrolysis of insoluble fluorinated inorganic minerals (800–1000 °C). Fluorocarbons could be destroyed through reactions with free radicals H, O, and OH or through single-molecule decomposition. Enhancing the temperature in the furnace and increasing the content of oxygen and hydrogen in the incineration materials were conducive to reducing the generation of fluorocarbons. By sampling and analyzing the bottom slag, bag filter ash and exhaust gas during the field test, the relevant pollutant discharge could meet the national emission standards. The waste heat utilization of high-temperature flue gas and the recovery of hydrofluoric acid and hydrochloric acid were realized. In the recovery of HF by water washing, the total absorption coefficients for 1# to 4# packed absorbers were 52.38 kg/(h m²), 39.96 kg/(h m²), 5.98 kg/(h m²) and 3.89 kg/(h m²), respectively. In the actual operation, alumina showed good corrosion resistance to high-temperature HF and could be used as bed materials or refractory materials. Low-temperature corrosion of HF occurred in the quenching heat exchanger, which was damaged after 6 months of continuous operation. High-temperature corrosion of HF occurred in the waste heat boiler. No significant corrosion was observed in the 24 months of operation.