Experimental and Theoretical Study of Minimum Fluidization Velocity and Void Fraction of a Limestone Based CO2 Sorbent

Authors: Chameera K.Jayarathna ^a,b, Britt M.Halvorsen ^a, and Lars-AndreTokheim ^a,b
a Department of Process, Energy and Environmental Technology, Telemark University College, Norway
^b Tel-Tek,Research institute, Porsgrunn, Norway

Source: Jayarathna, C. K.; Halvorsen, B. M.; Tokheim, L.-A. Experimental and Theoretical Study of Minimum Fluidization Velocity and Void Fraction of a Limestone Based CO2 Sorbent. Energy Procedia 2014, 63, 1432–1445

Abstract: Calcium looping is a promising technology for CO₂ capture as it may reduce considerably the energy penalty represented by the capture system. The CO₂ capture efficiency will strongly depend on the reactor configuration, solids residence time and thermal operation. As these parameters are also interdependent, the impact on the process can be better understood by process modelling and flow modelling. Use of model results can be very valuable in the design of the process. Properties such as minimum fluidization velocity and void fraction related to limestone particles are important parameters for process simulations as well as for simulations of flow behaviour in the reactor. Limestone (calcite) with a high content of CaCO3 can be a good sorbent material as it is readily available at low cost. Limestone from a local cement plant was used in this study. The material which had been pre-crushed in a mill at the plant was classified into four different size classes: 120-150 μm, 150-180 μm, 180-300 μm and 300-500 μm. A lab-scale fluidized bed made in plexi-glass, with a diameter of 146 mm and a uniform air distribution, was used to determine the properties of the sorbent. Four separate experiments were run for each group of particles. The minimum fluidization velocity and the related void fraction were then determined. Multiphase flow simulations were then carried out, using the computational fluid dynamics (CFD) software BARRACUDA®. The simulation results compared reasonably well with the experimental results.