Sulphur oxide (SOx) emissions are directly tied to the sulphur content in the fuel. However, switching to a low-sulphur fuel or natural gas is not always possible. If these fuels are not available or economical, SOx has to be removed from the exhaust gas by means of alkaline scrubbing.
Scrubbing away SOx
Alfa Laval PureSOx is a wet scrubber that effectively removes SOx from power plant exhaust gas. In addition, it traps up to 80% of the particulate matter (PM).
PureSOx scrubs the exhaust gas with either seawater or fresh water. When using seawater, which is naturally alkaline, it operates in an open loop where the water is legally discharged back into the sea. When using fresh water, the scrubber water is dosed with an alkaline additive and recirculated in a closed loop. Certain amount of used fresh water is led out of the system and additional new fresh water is produced on board. Before discharging the used water into the sea, it will be treated in a Water Cleaning Unit to meet IMO guidelines criteria. The separated sludge is led to the sludge tank on board.
Hybrid configurations with both open-loop and closed-loop modes are possible, as are configurations with multiple inlets. With multiple inlets, a single PureSOx scrubber can serve several engines at once.