Experimental Study Of Industrial Wastes And Mixture Absorbents For FGD

Wet flue gas desulfurization (FGD) is die main method in the world, absorbents and additives are the important factors for desulfurization efficiency and operation cost. This paper aims to study absorbents and additives included in the key science and technology project in Zhejiang province which is the Study of Equipment and Technology on Water-Film Dust Catcher Changed into Rotating-Stream-Tray Scrubber, studies several absorbents and organic additives for the abundant fly ash, waste marble, carbide lime, alkaline waste , and limestone, caculate the desulfurization capacity, and analyze the process mechanism. Furthermore, we also simulate the FGD process and optimize the process parameters in Rotating-Stream-Tray Scrubber (RSTS) for increasing desulfurization efficiency and reducing operation cost.The desulfurization capacity for carbide lime, alkaline waste, waste marble and limestone was 0 85, 0.75, 0.49 and 0.58g SOy'g absorbent respectively in absorber bottle But for fly ash and fly ash-marble mixture absorbent showed the results ranged from 0.12 to 0.25 gSOj/gfly-ash for different fly ash, and the fly ash-marble mixture absorbent could be used instead of limestone partly or entirely, which would reduce cost of absorbent greatly if the required efficiency is not high.The mass transfer-reaction process for fly ash, waste marble and organic acid enhanced waste marble slurry was conducted in a Double-Stirred cell. Changes of SO2 removal efficiency and slurry pH value with process time were experimentally determined, the mass transfer-reaction parameters were caculated and the process mechanism was analyzed. The results showed that the mechanism for fly ash and waste marble had similitude and difference, liquid phase resistance decreased with pH value, but the effect of reaction on mass transfer increased with pH value. The mass transfer was controled by gas film while hexanedioic acid concentration was 1 Ommol/1 and inlet SO^ volume proportion was less than 1000 X 10 5. Change of liquid phase concentration had little effect on gas phase total mass transfer coefficient. Hexanedioic acid accelarated the solubility of CaCOj, buffered the decline of slurry pH value, and enhanced mass tranfer rateWet FGD process for hexanedioic acid enhancing waste marble slurry and several alkaline solid wastes was studied on a RSTS. Change of SC>2 removal efficiency and pH value with process time were experimentally determined in different hexanedioic acid concentration, the formule of efficiency with pH value was regressed, and main process parameters were optimized for several alkaline solid wastes. The simulating results showed that SC>2 removal efficiency was increased by 10 percent, CaCOj utilization by 25 percent or more; and liquid/gas ratio was reduced substantially when pH=6.0 and C= 1.5%o. From the comparison study on desulfurization performance of several alkaline solid wastes, the order of good absorbent was carbide lime, alkaline waste, limestone and waste marble. Carbide lime and alkaline waste have better application potential.To sum up, the chosen absorbents and additive showed better desulfurization performance. The desulfurization process employing the study results could increase desulfurization efficiency and reduce operation cost effectively. Therefore, the absorbents and additive were expected to be commercially available.