Simulação computacional de uma válvula loop-seal acoplada a leito fluidizado circulante

Abstract

In this work, computational simulations of the gas-solid flow hydrodynamics inside a loop-seal valve coupled to a circulating fluidized bed system were carried out in order to compare numerical results with experimental measurements. Experimental tests and simulations were set under the same conditions to compare the static pressure profile and the solids circulation rate (Gs). Results of the solids fraction obtained from simulations showed a similar air-sand interaction behavior to those observed during tests. As expected, the increase of the aeration flow led to a more gas fraction presence in the loop-seal body. Moreover, the gas fraction was better distributed by simultaneously aerating the supply and recycling chambers, instead of just one of them. The static pressures obtained through simulations also were analyzed. In all cases, the static pressure in the supply chamber was always greater than in the recycling one. The deviation between the pressure values found by simulation and experiments were lower than 25%, suggesting the presence of a coherent pressure balance. Although similar trends were observed in the case of the external solids circulation rate (Gs), the values obtained through simulations were all greater than in tests, with deviations above 100% in several situations. This behavior could be explained due to the differences in the solid drag effect promoted by a real distribution of particle size (diameter range) in comparison with that of a unique particle diameter, as considered in simulations. The results of simulations presented in this work encourages new researches in this area.