Dioxin and Furan Abatement in the Al Industry

摘要

Taking into account the preconditions that favor the formation of dioxins and furans, there are two main dioxin/furan abatement technologies: Afterburner with quench Dry absorption Both technologies have their pros and cons. Afterburner systems have the obvious advantage that they actually destroy dioxins and furans by pyrolysis. However, the precursors are not removed from the gas stream, so there is a residual risk of reformation downstream of the system. Depending on individual process demands it may be reasonable to combine both techniques to comply with local permits. The entire gas volume will need to be treated. To that extent, the inherent high-energy consumption will become an issue. An afterburner does not address acidic compounds in the gas. In this case, an additional lime injection system is required anyway, which also produces residuals. The dry absorption process is a simple alternative for many applications. Most baghouses installed for aluminum furnaces are already equipped with an injection system that can be easily modified. Such systems offer simultaneous removal of acidic compounds, dioxins, and furans as well as even mercury from the emissions. There is a low additional energy demand. Absorption operates at low temperatures and a smart process design will need to consider this.