Wet Flue Gas Desulphurization Process Research Articles

Synthesis and Characterization of Zeolites Produced from Low-Quality Coal Fly Ash and Wet Flue Gas Desulphurization Wastewater.

This study investigated a low-energy-consuming procedure for the synthesis of zeolite materials from coal fly ash (CFA). Materials containing zeolite phases, namely Na–X, Na–P1, and zeolite A, were produced from F–class fly ash, using NaOH dissolved in distilled water or in wastewater obtained from the wet flue gas desulphurization process, under atmospheric pressure at a temperature below 70 °C. The influence of temperature, exposure time, and alkaline solution concentration on the synthesized materials was tested. In addition, chemical, mineralogical, and textural properties of the obtained materials were determined by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and cation exchange capacity (CEC). Cd(II), Ni(II), NH4+ cation, and Se(VI) anion sorption experiments were conducted to compare the sorption properties of the produced synthetic zeolites with those of the commercially available ones. Zeolitization resulted in an increase of CEC (up to 30 meq/100 g) compared to raw CFA and enhanced the ability of the material to adsorb the chosen ions. The obtained synthetic zeolites showed comparable or greater sorption properties than natural clinoptilolite and synthetic Na–P1. They were also capable of simultaneously removing cationic and anionic compounds. The structural, morphological, and textural properties of the final product indicated that it could potentially be used as an adsorbent for various types of environmental pollutants.

The Kinetics of Oxidation Inhibition of Magnesium Sulfite in the Wet Flue Gas Desulphurization Process

Using a stirred bubbling reactor, the kinetics of oxidation inhibition of MgSO3 from a magnesium-based wet flue gas desulphurization process were investigated. The reaction was found to be 0.7 order with respect to magnesium sulfite and −0.3 order with respect to sodium thiosulfate. The pH value should be controlled at a lower level in order to hamper the oxidation of sulfite. The apparent activation energy of the reaction was calculated to be 8.68 kJ/mol and a kinetic model has been established. Pilot tests showed that sodium thiosulfate can effectively inhibit the oxidation of magnesium sulfite in the magnesium-based wet flue gas desulphurization process.

Studies on Magnesium-Based Wet Flue Gas Desulphurization Process with a Spray Scrubber

As China became the largest SO2 emission country in the world after 1999, the State Environmental Protection Administration has targeted to reduce the national SO2 emission level since 2000, which required that all new thermal power units as well as the most existing ones must have flue gas desulphurization (FGD) systems installed. The domestic research on flue gas desulphurization is becoming the hottest topic in environmental science and engineering over the years. The sulphur dioxide removal was first applied in 1930s, nearly 100 different FGD processes and process variations have been studied. However, only a few results have been applied in the industry. Among these techniques, wet FGD processes are the most widely used in most countries because of their high desulphurization efficiency. The magnesium-based wet FGD process is one of the techniques to meet these requirements, which has been increasingly used on the industrial boiler in China because of its low investment, compact flow sheet, less land occupied, high efficiency, reliable operation, rare fouling and low price of the magnesium-based absorbent. MgSO4 is the byproduct from magnesium-based wet FGD process and can be sold as fertilizer. Though the FGD processes have been studied by a number of researchers, it should be noted that the magnesiumbased wet FGD process has not been the subject of many studies. The present work was undertaken to make a systematic Studies on Magnesium-Based Wet Flue Gas Desulphurization Process with a Spray Scrubber

Kinetics of Oxidation Inhibition of Sodium Sulphite in Wet Flue Gas Desulphurization Process

Kinetics of Oxidation Inhibition of Sodium Sulphite in Wet Flue Gas Desulphurization Process

Preparation and Evaluation of Fe<sub>2</sub>O<sub>3</sub>/Ceramic Composites for Flue Gas Desulfurization

Ceramic supported ferric oxide composites were synthesized by impregnation- precipitation (I) and sol-gel (II) methods using FeSO4as a precursor. We investigated the effect of the calcination temperatures on the structure, morphology, and agglomeration of supported ferric oxide. It has been found that Fe2O3was stabilized when the as-synthesized composites were calcinated at 330-360 °C under 10% (v/v) O2/N2mixture, and the calcination temperature was chosen as 350°C . The SEM images demonstrated that for the composite I, which was prepared by method (I), Fe2O3 nanoparticles were distributed on the surface and pores of the ceramic; while for the composite II, which was synthesized by method (II), Fe2O3thin layer was covered the surface of the ceramic. EDS analysis showed 7.9% (wt) ferric oxide had been supported on the composite I and up to 13.3% (wt) ferric oxide on the composite II. XPS analysis revealed that the valence of iron was +3 on both composites. Fe2O3/ceramic composites were used as the catalysts for low temperature wet Flue Gas Desulphurization (FGD), and demonstrated higher SO2removal efficiency. Because of the excellent hydrophilicity of ceramic and high dispersibility of Fe2O3 on ceramic surface, this catalyst had high SO2removal efficiency at 60°C even at pH2O3/ceramic composites, prepared by a simple, reproducible impregnation-precipitation and sol-gel method, was an inexpensive, active catalyst for S(IV) catalytic oxidation in wet FGD process in an economical feasible temperature range.

Prediction of Uncatalysed Calcium Bisulphite Oxidation Under Operating Conditions Relevant to Wet Flue Gas Desulphurization Plants

Wet limestone scrubbing is the most common flue gas desulphurization (FGD) process. In this process, oxidation of calcium bisulphite plays a major role both by determining the dewatering properties of the obtained sludge and the production of gypsum of high quality. In order to contribute to the simulation of the wet limestone FGD process, in the present paper a comprehensive model for isothermal gas–liquid stirred tank reactors has been used. Based on the assumption that the reactions are zeroth order with respect to gaseous reactants, the model requires appropriate physico-chemical parameters which are taken from the literature. The model was used to quantitatively interpret some literature experimental data concerning uncatalysed calcium bisulphite oxidation performed in a continuous stirred tank reactor. In particular, the model is capable of confidently predicting the transition from chemically to mass transfer controlled regime occurring when changing the operating conditions.