Dioxin Removal Technologies

There are several basic techniques for removing dioxins and furans (D/F) from a process gas stream:

Activated Carbon Injection (ACI)

ACI is a technique of injecting fine carbon particles in a process gas stream. The fine carbon particles are treated by exposing them to steam in order to "activate" the surface by expanding the pore structure and thus creating millions of microscopic "tunnels." The enhanced pore structure of the activated carbon serves as a matrix of sites wherein smaller consituent gas molecules, such as D/F, will lodge themselves and thus be segregated from the larger, less noxious molecules, purifying the gas stream.

Evaporative Gas Cooling (EGC)

Whereas ACI is a capture technique, EGC is implemented as a prevention technique. D/F are generated from precursor elements resulting from the combustion of chlorinated compounds. This generation occurs within a rather narrow temperature window of 400-200 °C (750-390 °F). The shorter the time the gases send in this temperature window, the lower the amount of D/F produced. EGC is used to rapidly cool the gases through this temperature window, thus eliminating the formation of D/F.

Dry Sodium Bicarbonate Injection (SBI)

SBI is a technique of injecting fine bicarbonate of soda particles in a process gas stream. Granular bicarbonate of soda is ground to a fine particle and injected directly in the gas stream. After exposure to the hot gas stream, the bicarbonate of soda is converted to sodium carbonate, activated by exposure to the gas stream, resulting in a particle with an activated microstructure, analogous to that of an activated carbon particle. The enhanced pore structure of the sodium carbonate particle serves as a matrix of sites wherein smaller consituent gas molecules, such as D/F, will lodge themselves and thus be segregated from the larger, less noxious molecules, purifying the gas stream. SBI is also reactive to acid gases, making it the obvious choice for incinerator applications with modest acid gas content.