A DFB Calcium Looping facility has been built utilizing a 12.4 m high, 70 mm diameter riser and a 114 mm diameter Bubbling Fluidized Bed (BFB), as shown in the Figure below.
One reactor is used as carbonator (1) and theother as regenerator (2). Novelty of this rig is the control of the solid looping rate between the beds by a cone valve. Flue gas enters the carbonator, while CaO flows from the double exit loop seal (3) to the carbonator. The solid looping rate is controlled by varying the cone valve opening and the absolute pressure. A molar flow of partially carbonated CaO to the incoming, exits the carbonator through the overflow (6) and flow to the regenerator. The regenerator off gas proceeds to the stack while the riser entrainment is separated with a cyclone (9) and reaches the double exit loop seal. The CaO looping rate proceeds to the carbonator and the rest of the flow returns to the riser through the loop seal weir (11).
The carbonator, regenerator and solid circulation system are electrically heated. Exiting flue gases from regenerator and carbonator pass eventually through candle filters (13). For control of the facility and data acquisition LabView® software is used. Electrical heaters are controlled automatically through type N thermocouples. Pressure is measured through differential and absolute transducers. All gas flows are controlled with Mass Flow Controllers (MFCs) except loop seal aeration which is controlled by rotameters. The carbonator is fluidized with a synthetic mixture of CO2 and N2, while the regenerator and loop seals are fluidized with air.
Scheme of IFK Calcium Looping DFB facility: (1) BFB carbonator, (2) riser regenerator, (3) double exit loop seal, (4) cone valve, (5) pressure control valve, (6) BFB overflow, (7) lower standpipe, (8) lower loop seal, (9) cyclone, (10) upper standpipe, (11) loop seal weir, (12) quartz standpipe segments, (13) candle filters, (14) electrical gas pre-heaters (Charitos et al; 2010)