Effects of liquid content and surface tension on fluidization characteristics in a liquid-containing gas-solid fluidized bed: A CFD-DEM study

摘要

The fluidization process within gas-solid fluidized bed reactor can be intensified by adding liquid, as it can enhance mass and heat transfer between gas phase and solid phase. With the help of computational fluid dynamics(CFD) and discrete element methods(DEM), fluidization characteristics are investigated at different liquid contents((V) over cap) and surface tension(Bo(g)). To be specific, the bed expansion ratio, particle concentration and particle velocity profiles are compared and analyzed. Numerical simulations show that Bo(g) should be less than 5 at (V) over cap = 0.013. At this recommended range, liquid addition makes interparticle force increase and has little effect on fluidization performance. From transient particle agglomeration behavior, the Bo(g) increase is more likely to enhance interparticle force, resulting in obvious particle agglomerations during fluidization process. The variation of stagnation zone height can be reflected from the abrupt increase of particle velocity in annulus region. It can be found that (V) over cap increase reduces particle velocity at critical height but Bo(g) increase is more likely to cause larger stagnation region. By analyzing the distribution of spout, annulus and fountain regions at different (V) over cap and Bo(g), the annulus region expands with (V) over cap increase below the initial bed height while the spout region expands with Bo(g) increase.