Re-generable and functionalised charcoal for submarine atmosphere control

The enclosed atmosphere of a submarine must be constantly monitored and controlled to ensure the safety of the ships company. Much like National Aeronautics and Space Administration’s (NASA) Spacecraft Maximum Allowable Concentrations (SMAC) the Royal Navy (RN) have set action limits for commonplace contaminants such as Volatile Organic Compounds (VOC). Primary VOC control is achieved via surface adsorption onto activated charcoal. Over time the removal capacity of this charcoal diminishes due to the saturation of adsorption sites. This subsequently leads to filter beds requiring replacement and disposal. This constitutes a significant logistical and financial burden. Extending the usable lifetime of activated charcoal by re generation would reduce these costs. This paper discusses the feasibility of re-generating activated charcoals for repeated use on board submarines. The capacity of submarine activated charcoal was determined using typical atmosphere contaminants with a range of boiling points. Thermal, vacuum and Joule based re-generation methods and subsequent adsorption isotherms are presented. The effect of repeated adsorption and regeneration is discussed. Ammonia contamination originating from the carbon dioxide removal plants is also of concern. The findings of a laboratory investigation using alternative functionalized adsorption media to remove these compounds is presented.