Effect of operation conditions on particulate matter removal by a packed-bed wet scrubber for a small-scale biofuel boiler

In 2013 the EU’s Clean Air Policy Package was established, aiming to reduce air pollution to half by 2030 compared to the level in 2005. Small-scale (<500 kW)biofuel boilers play a key role in particulate matter emission, and exposure to particulate matter even in the short term can cause different diseases. With the aim of reducing particulate matter emission in Europe, this study presents an approach to improve the removal of particulate matter emitted by small-scale boilers. A biofuel combustion boiler was equipped with a packed-bed wet scrubber, and the flue gas emitted through combustion was cleaned through the wet scrubber using a saltwater mixture. The performance of a packed-bed wet scrubber was investigated under different operating conditions. The effect of the salt concentration of the absorption solution, the temperature of the absorption solution fed to the absorber, and the height of the packed-bed material on the particle collection efficiency were measured. The operating conditions were selected based on the results obtained in a previous computational fluid dynamic simulation study. The results obtained in the present study show that an absorption solution temperature of 30 °C and an absorption solution concentration of 75 % with a full height of the packed-bed material lead to the best performance in the system. Totally keeping the absorption solution temperature as low as possible, increasing the absorption solution concentration, and raising the packed-bed material height could improve the particle collection efficiency by enhancing the effect of the diffusiophoresis and thermophoresis forces and the contact time between the flue gas and solution.