Influence of the Lime Slurry Droplet Spectrum on the Efficiency of Semi‐Dry Flue Gas Desulfurization

Abstract

A numerical model based on computational fluid dynamics is presented to predict the efficiency of a semi-dry flue gas desulfurization process. The Euler-Lagrange particle tracking method is used to predict both evaporation and mass transfer between the flue gas and the lime slurry droplets. The overall desulfurization process is split into two periods, i.e. the constant-rate and the falling-rate period, during which the fundamental chemical reaction between sulfur dioxide and calcium hydroxide is modeled. The absorption efficiency is calculated for different spray characteristics, taking into account different size spectra of the lime slurry droplets characterized by different standard deviations for a constant mass mean diameter d 50 of 25 lm. The results are compared with published experiments and show excellent agreement as well as a significant role of the spray characteristics in the FGD efficiency.

Comparative Study of Sorbents for Spray Dry Scrubbing of SO2 from Flue Gases

“…Low conversion for all of the sorbents at high temperatures (180 °C) was observed mainly due to an accelerated droplet evaporation rate, which limits the droplet’s lifetime for SO 2 absorption and sorbent conversion. These observations are in good agreement with the literature and have been attributed to negligible internal mass transfer resistances for SO 2 at high stoichiometric ratios . The prime objective of a scrubbing system is to remove SO 2 from flue gases to ranges within the applicable regulatory limits.…”

“…These observations are in good agreement with the literature and have been attributed to negligible internal mass transfer resistances for SO 2 at high stoichiometric ratios. 33 The prime objective of a scrubbing system is to remove SO 2 from flue gases to ranges within the applicable regulatory limits. South African regulatory requirement on SO 2 emission for large-scale coal utility plants is 1000 mg/Nm 3 (382 ppm).…”

Enhancement of Mass Transfer between Flue Gas and Slurry in the Wet Flue Gas Desulfurization Spray Tower

“…Although the quality of the sprayer has an important influence on the desulfurization effect in the WFGD system, however, this work focuses on the effect of the local flow regime on mass transfer in the desulfurization process; therefore, we did not take the quality of the sprayer into account.…”

Flue‐Gas Desulfurization by Using a HiGee Electric‐Field Device

“…On the other hand, semidry flue gas desulfurization exhibits the characteristics of dry desulfurization plus, to some extent, those of wet desulfurization technique. Despite the advantage of lower capital costs than those of the wet desulfurization method, its application is still limited by instability, unreliability, and low SO 2 removal efficiency . Wet flue gas desulfurization is the most popular and widely applied technique owing to its high rate of utilizing desulfurization reagents and high SO 2 removal efficiency .…”