Removal of SO₂from Flue Gas Using Basic Aluminum Sulfate Solution with the Byproduct Oxidation Inhibition by Ethylene Glycol

Abstract

This paper presents a novel wet flue gas desulfurization (FGD) technology based on a basic aluminum sulfate (BAS) desorption regeneration process, in which ethylene glycol (EG) was first employed to inhibit the byproduct oxidation. The operating parameter effect on SO2 absorption efficiency and oxidation efficiency of sulfite was thoroughly examined in a lab-scale bubbling column. The results indicated that both the amount of aluminum and basicity play important roles on the desulfurization time with above 90% absorption efficiency. The BAS-based desulfurization process was more suitable for a low temperature and low gas flow rate. High inlet SO2 concentrations may contribute to the mass-transfer rate of SO2, and the SO2 absorption efficiency remained above 90% when the pH value was over 3.10. With the addition of 1% (v/v) EG in BAS solution, the oxidation efficiency dropped dramatically from 86 to below 10% (in 120 min). On the basis of the two-film theory, a model of the SO2 absorption process was developed and the mass-transfer characteristics were analyzed. The calculation results indicated that the SO2 absorption process for this system was decided by a combination of both the gas- and liquid-phase diffusion controls.

Efficient Removal of SO2 from Flue Gas with Phosphate Rock Slurry and Investigation of Reaction Mechanism

“…Generally, a solid absorbent, which is the dominant absorbent type from WFGD processes, shows the advantage of low cost and is easily separated. However, on the one hand, as to the WFGD process, most of the present studies remain around the laboratory scale, though some can realize end-use applications. , On the other hand, using industrial solid wastes of steel slag slurry and fly ash as adsorbent reflects the significance of green and environmental process, but some limitations are suggested when it comes to the specific phosphorus chemical industry, which includes the source and the cost of raw material. Besides, the currently used wet limestone flue gas desulfurization process faces the drawback of secondary pollution, , owing to the formation of residual desulfurized gypsum, a byproduct from the desulfurization process, which needs to be discharged into the environment .…”

Sulfur Dioxide Desorption Characteristics of Basic Alkali Aluminum Sulfate Desulfurization Rich Liquid by Falling Film Evaporation with a Spring Tube

“…Afterward, the gas phase was taken out by the vacuum pump (13). Meanwhile, the second vapor was condensed in the cooling equipment (9), and the SO 2 was absorbed by the NaOH solution (12).…”

“…Preparation of the BASS-SO 2 . The BASS was prepared according to a reported method by Chen et al 9 The BASS-SO 2 had to be prepared not long before the desorption experiment was conducted. As described in Figure 4, the pure SO 2 was injected into the BASS (volume of 19 L, aluminum concentration of 20 g/L, and basicity of 30%).…”

“…This approach has significant economic benefits, since the absorbent could be regenerated and prepared with cheap raw materials of Al 2 (SO 4 ) 3 and CaCO 3 . 9 As mentioned earlier, the research of BASS in desorption characteristics needs to be paid much more attention, especially in its industrial applications.…”

Falling Film Evaporator for Desorption of Basic Aluminum Sulfate SO2-Rich Solution and Enhancement of Heat and Mass Transfer

“…Compared with the basic aluminum sulfate–gypsum method, the basic aluminum sulfate desorption method , has attracted wide attention owing to high desulfuration efficiency, recycling of desulfuration liquid, low process liquid–gas ratio, and recyclability of recycled SO 2 . The existing research on basic aluminum sulfate desorption of fuel gas desulfuration is focused on SO 2 absorption and starts from the perspectives of mechanism, dynamics, influence factors, − and inhibitors but has rarely concerned SO 2 desorption. Experiments on the basic aluminum sulfate desulfuration desorption process with water bath heating show the SO 2 desorption efficiency under the optimal conditions is about 70% .…”