Experimental and numerical study on effects of deflectors on flow field distribution and desulfurization efficiency in spray towers

Abstract

The desulfurization efficiency of a spray tower that uses Wet Flue Gas Desulfurization (WFGD) technology can be improved by adding deflectors. This paper experimentally and numerically investigates the performance of a Deflector Spray Tower (DST) and then compares the results with an Open Spray Tower (OST) and Tray Spray Tower (TST). An experimental facility (i.e., 1:15 scale pilot plant) is established based on the WFGD system of an actual 600MW coal-fired power plant. The experiment simulates gas and liquid hydrodynamics inside the spray tower. The continuous phase is described in an Eulerian framework and liquid droplet motion is computed by the Lagrange approach. Sulfur dioxide absorption is modeled on the two-film theory, appropriate empirical correlations and semi-empirical correlations. The effect of the tray on the flow field is considered under porous media conditions. A comparison of experimental and numerical results validates the numerical simulations, showing that the Euler-Lagrange approach accurately predicts the flue flow field and liquid droplet distribution. Here, results show that deflectors positively affect flow field structure in the spray tower. The deflectors rearrange the single-phase flow field of the gas and partially solve the bias flow due to the single inlet. Therefore, peak velocity in the tower decreases such that the pressure drop for DST is 14.1% lower than the pressure drop for OST. In addition, compared with TST, DST is superior in tower resistance, with a decrease of approximately 39.7%. The SO2 desulfurization absorption model is verified in an actual 660MW power plant. Here, desulfurization efficiency is 89.6% for OST, 92.5% for TST and 96.7% for DST at the design parameter.