Optimal Operation Reasearch Of Limestone-gypsume Wet Flue Gas Desulfurization For Coal-fired Power

Wet limestone flue gas desulfurization technology is applied most widely for coal-fired power plants all over the world at present. In this paper, we did systematic research on the hot spots about WFGD. The main research this paper carried out as follow:1) This paper investigated the influence of different kinds of water on limestone activity which are always used in WFGD system by adding acid-sta method. From high in the end are:ground water> recycling water> Circulating cooling water. Because the distinction of these kinds of water are the different concentrations of Cl-SO42- and corrosion inhibitor(TP), the impact of variation concentration of these ion and additive on the dissolution of limestone was studied by the same method. Research show:Cl- inhibited the dissolution of limestone, and SO42- promotes the dissolution of limestone. Lower TP concentrations promote the dissolution of limestone, but higher TP concentrations inhibited the dissolution of limestone. Then do some experiment to study reactivity of limestone in the filtrate of sorority in WFGD absorption tower. The Inhibition of filtrate is Comprehensive effect of different concentrations of these ions. In order to research the water quality of the liquid in absorption town, the impact of pH value and aeration were carried out by titration with sulfurous acid using pH-stat method. At the same time, the impact of SO32-, Cl- on the dissolution of limestone was also investigated by pH-stat method. Control the slurry pH in a moderate range of 5.0-5.5, Cl- concentration below 8875mg/L, the sulfite concentration does not exceed 2.5mmol/L, so that these factors does not impinge the dissolution of limestone Obviously.2) Through on-site experiment of chemical monitoring, this paper studied the impact of different pH condition, chlorine ion concentration, sulfite concentration and the oxygen density in flue gas on the composition change of the liquid in absorption tower. Control the slurry pH in 5.5, Cl- concentration below 10000mg/L, the sulfite concentration does not exceed 2mmol/L, these can supply strategy for abnormal operation of WFGD. The influence of chlorine ion to the dehydration of gypsum is studied based on on-site experiment, and the result show that chlorine ion Inhibit the dehydration of gypsum. Using the factor analysis method, the main factors affecting the dehydration of desulphurization of gypsum is divided into three factors, according to the monitoring date desulfurization system during half year. The roles of three factors were accounted for 48.6%,17.3% and 12.8%.3) Based on the conventional operation data in one 300MW WFGD system, some main factors including pH, liquid-gas ratio, the temperature, concentration of SO2, dust, and O2 of the gas flow, and the density of the liquid in absorption tower were studied by single factor analysis, which supplies reference to the further research. By the method of multi-regression, using SPSS analyses the operation data in this 300MW WFGD system, three possible forms of model reaching significant level are studied critical factors affecting the optimum operation of WFGD are extracted. On the condition of reaching the target desulfurization efficiency, optimal operating parameter has been put forward based on this multivariate regression model.