Study On Optimal Operation For Wet Limestone-gypsum FGD System Of Coal-fired Power Plant

Flue Gas Desulfurization (FGD) is an effective technology of reducing sulfur dioxide emission and controlling sulfur dioxide pollution. It is widely applied in coal mine thermal electricity industry due to the Mature technique and low operating costs. With limestone absorbing the SO2 to put the concentrations of SO2 down in fume, and the gypsum is byproduct.This study is based on the desulfurization project of east power plant. Through analyzing the factors affecting on the desulfurization efficiency, which including fumes temperature and concentration in the entrance, flow velocity, oxygen content of initial fumes, pH values of serum, calcium sulfur ratio, vapour-liquid ratio, serous fluid density et al., to determine the optimum technological parameters of those factors; Then, For decreasing power consumption and desulfurizer usage, the measure on promoting demister efficiency, optimized serous fluid cycle pump combination and applying desulfurizer reasonably was studied to achieve economical operation of coal mine power plant.The main conclusions of the study:(1) In the conditions as, entrance fumes temperature of absorbing tower under 132℃, 3.8m/s flow velocity,5.2 mg/Nm3 oxygen content and 3000mg/Nm3 SO2 concentration of initial fumes, pH of serum within 5.2-5.6,1.03 vapour-liquid ratio,17 L/m3 vapour-liquid ratio, serous fluid density within 1100-1150kg/m3, the desulfurization efficiency is best.(2) In the premise of desulphurization rate stability, The optimal circulating pump: lower concentration SO2 and lower unit load,1 circulating pump can get 90% of desulphurization rate; unit load below 175MW and SO2 concentration 1500～3000mg/Nm3, or unit load above 175MW and SO2 concentration below 2000 mg/2 sets,2 pump is enough to get the desulphurization rate 93%; higher concentration SO2 and lower unit load,3 sets circulating pump is necessary to insure the desulfurized efficiency 90%. With the appropriate slurry pump operation,170 million Yuan can be saved on electrical cost annually.(3) Keeping demister and precipitator washing and maintenance frequently, keeping grout in reasonable pH value and reducing the content of dust is important, which will raise demister effect, and then the desulfurized efficiency.(4) Adding desulfurizer will bring good economic and social benefits by making FGD desulfUrization efficiency rising from 79.6% to 90.4%, reducing the number of circulating pumps, and reducing power consumption and operating cost.Our study offer valuable reference for FGD optimum and economical operation of coal mine power plant.