Preparation of Active Absorbent for Dry-Type Flue Gas Desulfurization from Calcium Oxide, Coal Fly Ash, and Gypsum

Abstract

As compared to a commercial absorbent prepared from Ca(OH) 2 , gypsum (CaSO 4 ) and coal fly ash, an absorbent prepared by use of CaO in place of Ca(OH) 2 , exhibited a higher activity for dry-type flue gas desulfurization . The order of the addition of the raw materials in the slaking procedure has much effect on the activity of the resulting absorbent. The activity of the absorbent increased further upon hydrothermal treatment following the kneading procedure. The period of hydrothermal treatment was reduced to 3 h to attain the activity which exceeds 20% of the activity of the commercial absorbent which requires an optimum hydrothermal treatment period of 10 h. The activity enhancement by use of CaO is considered to result from exothermic heat of slaking CaO. At a high temperature, the reaction of CaO with a SiO 2 component included in the coal fly ash facilitates the formation of calcium silicate. The formation of calcium silicate was suppressed by the existence of CaSO 4 in the slaking procedure.

Fabrication of Multifunctional Hybrid Composites Using Fly Ash to Control Environmental Pollutants: A Review

“…In addition, SO2 and SO3 are harmful gases that contribute to formation of submicron acid particles that can penetrate human lungs and be absorbed into the bloodstream [144]. Many researchers have reported that blending FA with Ca(OH)2 or CaO can produce an adsorbent via a hydration process with a better SO2 reduction than that of hydrated lime [145][146][147]. Lee et al [148] found similar results, as shown in Figure 13.…”

Removal of Sulfur Dioxide From Flue Gas Using Absorbent Prepared by Water and Steam Hydration

“…For pressure hydration, absorbents with a BET specific surface area of 2.5-64.3 m 2 /g were obtained 5 . On the other hand, for steam hydration and water hydration, values of 24 m 2 /g 5 and 18-73 m 2 /g were obtained respectively 3,7 . It can be seen that the products of the pozzolanic reactions differs in each case depending on the methods of absorbent preparation as well as the fly ash composition and absorbents preparation parameters.…”

“…A wet-type FGD unit based on a limestone-gypsum method is most widely used and suitable for large-scale boilers such as those installed in coal or oil-fired power stations 3 . The wet-type FGD process has the advantage of using inexpensive limestone as a neutralizing agent, to produce commercial gypsum and to remove sulfur dioxides at high efficiency.…”

“…The influence of the absorbent micro-structural properties such as the BET specific surface area, which is one of the major parameters affecting the efficiency of the absorbent in removing SO 2 , has been mentioned by a number of researchers 1,3,[5][6][7][8][9][10] . Recently, Ishizuka et.…”

Dry SO2 Removal Process Using Calcium/Siliceous‐Based Sorbents: Deactivation Kinetics Based on Breakthrough Curves

“…One of these processes is the dry-type desulfurization process operating at low temperature and which utilizes dry sorbent. The dry-type method for flue gas desulfurization (FGD) has recently attracted considerable research interest due to the drawbacks of wet-type methods [1,2].…”