| dc.description.abstract | SCR was mainly applied to removal of NOx as initially developed and now it has been used to abate dioxin emissions as well. Presently, abatement of dioxin using catalysis has become the mainstream technology. This study can be divided into two parts including field tests and pilot-scale system tests. The former focuses on sampling and investigating the control of dioxin emissions for existing SCR devices. The latter utilized several kinds of activated carbon-supported catalysts (Cu/C, Fe/C and Cu-Fe/C) to evaluate the feasibility of removing dioxins.
Regarding the tests conducted in field, the results showed that removal efficiency of gas-phase dioxin achieved with SCR at metal smelting factory was 66% while that of PCDD and PCDF were 67.6% and 65.4%, respectively. For the MSWI, the SCR could remove 95% of gas-phase dioxin, in which 96% of PCDD and 97% of PCDF were removed. The surface area of the honeycomb-type V2O5/WO3/TiO2 catalyst (870m2/m3) adopted by MSWI is much higher than that of plate-type V2O5/WO3/TiO2 catalyst (320 m2/m3) utilized by metal smelting factory, resulting in the higher removal efficiency obtained in MSWI.
The source of pilot-scale system sampling in metal smelting factory conducted the removal efficiencies achieved by utilizing Cu/C, Fe/C and Cu-Fe/C catalysts were as high as 95%. As for source of pilot-scale system sampling in the MSWI, the removal efficiencies achieved with Cu/C and Fe/C catalysts were more than 90%.
In the metal smelting factory, the destruction efficiencies of three catalysts at 150℃ were about 20-30%. However, the destruction efficiencies obtained with Fe/C and Cu-Fe/C catalysts increased with increasing temperature. At 250℃, the destruction efficiency achieved with Fe/C catalyst was 78%. In the MSWI, the destruction efficiencies obtained with activated carbon-supported catalysts (Cu/C and Fe/C) were 30-40% when the temperature was kept at 150℃. For the Fe/C catalyst, the obtained destruction efficiency at 200℃ was 66%; however, once the temperature is increased to 250℃, the destruction efficiency was reduced to 57%.
For the results of metal smelting factory, dioxin were generated through catalysis when the temperature of the Cu/C catalyst was 200℃ or 250℃ and that of the Cu-Fe/C catalyst was 250℃. In the MSWI, dioxin were generated through catalysis while the temperature of the Cu/C catalyst was 250℃. Compared with the results obtained with Cu/C and Fe/C catalysts in the metal smelting factory, it can be concluded that dioxin would be more easily produced when Cu/C catalyst is applied. Although the Cu-Fe/C contained Cu as well, no dioxin was generated at 200℃, which might be relevant to the Cu content and operating temperature. | en_US |