Removal of CO2 from a submersible atmosphere by scrubbing with water: Experiments in a single column

In order to explore methods of removing CO2 from submersible habitats with sea water, gas scrubbing experiments (using tap water, and tap water with 3.5 wt% sea salt) were performed in a 108 mm i.d. pilot-scale column, investigating the removal efficiency of CO2 (e.g. at 2 vol%) from a gaseous stream. The performance of this column fitted with 5 spray nozzles was compared with a column packed with 1/8th in. Dixon rings (packing depth = 1480 mm). More detailed experiments were then performed in the column packed with Dixon rings at: liquid flows from 4 to 8 dm3 min−1; gas flows 18 and 36 N dm3 min−1, column pressures = 1 and 4 bar(g); column temperatures approximately 5 and 17 °C. In general, CO2 removal increased as column operating pressure was increased, or fluid temperature was decreased. When approaching low gas outlet CO2 levels at the top of the column (e.g. 0.1 vol%), the concentration of carbonate species in the tap water (fed into the column) restricted further improvements in the performance of the column.

In experiments in a short column with Dixon rings (packing depth = 180 mm), using fresh water in each column, the performance of a multi-column eight chamber compact scrubber was simulated, and shown to be significantly better than a single tall column.