Characteristics and so₂ capture capacities of sorbents prepared from products of spray‐drying flue gas desulfurization

Abstract

The characteristics and the SO2 capture capacities of sorbents prepared from products of spray‐drying flue gas desulfurization (FGD) have been studied. Sorbents were prepared by first slurrying Ca(OH)2 and CaSO3 and/or CaSO4 with and without the addition of fly ash and then drying. Compared to the use of pure Ca(OH)2, the SO2 capture and Ca(OH)2 utilization decreased for sorbents prepared without fly ash and increased for sorbents with fly ash. Flakelike ill‐crystallized tobermorites were observed for all the sorbents containing fly ash. In addition, significant amounts of needle‐shape Ca4Al2(OH)12SO4 . 6H2O and Ca6Al2 (OH)12(SO4)3 . 26H2O (ettringite) were also observed for the sorbents containing CaSO3 and/or CaSO4. These newly formed compounds dissociated into CaSO3 . 0.5 H2O and inert precursors upon sulfation, and were responsible for the high SO2 capture capacities and Ca(OH)2 utilizations of the sorbents prepared with fly ash.

Effect of NaOH Addition on the Reactivities of Iron Blast Furnace Slag/Hydrated Lime Sorbents for Low-Temperature Flue Gas Desulfurization

“…This finding explains the results of surface area measurement because calcium silicate hydrates are high surface area foil-like materials. 4,[11][12][13][14] SEM observations 5,6 showed that the raw BFS particles have smooth surfaces, but the surfaces of the particles are very rough after hydration with water or NaOH solution, indicating that the dissolution of BFS had occurred during the hydration process. The SEM observations also showed that the particles of BFS/HL sorbents not containing NaOH are mainly composed of foil-like substances, and highly porous, but few foil-like substances can be observed, and the particles are less porous for sorbents containing NaOH.…”

Factors affecting wollastonite carbonation under CO2 supercritical conditions

“…The conversion was calculated using the following equation: where 40 and 44 are the atomic weights of calcium and molecular weight of carbon dioxide, respectively; X stands for the conversion; and M stands for the weight of wollastonite, which contains 1 gmol of calcium, that is, 40 g of calcium. The values of M for the three wollastonite samples were 128.16, 136.03, and 134.58 g/gmol of calcium, respectively, as determined through EDTA titration 9. If a rock is composed of pure wollastonite, M is equal to 116.16 g/gmol of calcium, which is the molecular weight of CaSiO 3 .…”

Evaluation of various additives on the preparation of rice husk ash (RHA)/CaO-based sorbent for flue gas desulfurization (FGD) at low temperature

“…Apart from that, the beneficial effect of additive addition is supposedly due to the presence of additive that might increase the dissolution rate of silica from RHA. The increase in the dissolution of silica will ultimately increase the formation of Si-Ca complex that has a high SSC [5][6][7][8][9]25]. However, the XRD pattern of sorbents prepared with the addition of NaOH (shown in Fig.…”

“…3a and b) showed the prepared sorbents were mainly composed of carbonate (CO 3 2− ) due to a broad band near 1450 cm −1 and a sharp band near 875 and 712 cm −1 [26,27]. A sharp vibration band approximately at 3640 cm −1 usually caused by the stretching of CaO-H [25]. The bands around 460-470 cm −1 (Si-O-Si band) and 795 cm −1 (Si-O-Si symmetric strength) are observed for amorphous silica.…”