Dry scrubbing of municipal solid waste incineration flue gas using porous sodium carbonate produced via vacuum thermal treatment of sodium bicarbonate

Sodium bicarbonate is among the alkali chemicals used for dry scrubbing in incineration flue gas treatment. It is generally pulverized into fine particles of ~ 20 µm to increase the specific surface area for higher reaction efficiency with acid gases. However, problems such as bridging or blocking in the storage and supply system can easily occur with pulverized sodium bicarbonate (PSB). Pulverization with the addition of a dispersing agent is performed as a measure that leads to an increase in chemical cost. In this paper, vacuum thermal treatment was examined to produce porous sodium carbonate from coarse sodium bicarbonate (CSB). Pressure, temperature, and heating time were tested to produce sodium carbonate with a specific surface area that is equal to or higher than that of the sodium carbonate (REF) obtained from PSB by spraying it into a fabric filter at 180 °C. Sodium carbonate (P30) with a higher specific surface area than REF was obtained by treating CSB at 180 °C under 30 kPa for 1 h. P30 was proven to have 1.8 times higher HCl removal efficiency than REF. This novel method is expected to resolve the existing issues through both spraying PSB and reducing the air resistance at the fabric filters.