SALT at Scale

Pilot-scale testing will be conducted using 5 and 20 kg quantities of silica-PEI in the facility at the University of Nottingham which was constructed in 2019. The units comprise of a bubbling fluidized-bed type sorption reactor, a bubbling fluidized-bed type desorption reactor, and a cyclone for separating gas and solids.    For adsorption, a circulating fluidized bed can also be used and this has the advantage of greater throughput with more rapid solids circulation.  For solids handling, a transport system circulates adsorbents from the sorption reactor to the desorption one and the solid circulation rate is controlled by manipulating rotary valves.  The rigs have gas recirculation systems for the CO2-rich gas discharged from the desorbers.  The unit operates with 5 kg for the bubbling bed adsorber and 20 kg for the circulating bed adsorber.  In both modes, the unit can run on both actual and simulated flue gas.  Bubbling beds give longer residence times and generally higher dynamic adsorption capacities than fluidised-beds but lower CO2 capture rates due to the longer solids residence times during adsorption.

Previous work indicates that CO2 dynamic adsorption capacities of over 7% and CO2 capture levels approaching 90% were achieved in bubbling-bed mode.  Due to the improved silica-PEI formulations and pilot-scale facility with moisture blanketing at all stages, it is anticipated that significant improvements will be achieved on our previous studies with no significant loss of activity of timescales of about a month. The test programme here will provide a detailed comparison between bubbling and fluidized-bed operation for the adsorber.