Research On Overall Operation Optimization Of The Wet Flue Gas Desulfurization System In Large Scale Coal-fired Units

Along with the development of national economy and the stricter and stricter requirement of environmental protection, the flue gas desulfurization systems (FGD) have been widely introduced into China’s coal-fired units and most of them adopt the limestone-gypsum wet flue gas desulfurization technology. They have reduced the emission of SO2pollutant from China’s coal-fired units, but brought great additional material and energy consumptions at the same time. Thus how to guarantee the desulfurization effect in FGD system and reduce its material and energy consumptions effectively at the same time plays a significant role of reducing consumptions, improving the comprehensive performance of coal-fired units, and the achievement of national energy conservation strategy.In this paper, based on the basic principles of energy balance, chemical reaction balance, material balance and the actual operation data, the material and energy models have been built at first, providing a foundation for the research on operation optimization of the FGD system. Then by analyzing the impacts of several key parameters (mainly including liquid gas ratio (L/G), flue gas velocity, flue gas temperature, calcium sulfur ratio (Ca/S), pH value and SO2concentration) on the desulphurization performance characteristics (including desulfurization efficiency, energy and material consumptions), the optimal operation strategies of main energy consumption equipments for energy saving have been studied, and on these basis an overall optimization operation way of FGD system is put forward, that is, considering the specific conditions of a coal-fired unit, try to select and control the key desulfurization operation parameters in reasonable numerical ranges, guaranteeing a better desulfurization effect and at the ame time reducing the operation cost as much as possible. Finally taking a typical1000MW FGD system as an example, its optimization operation plans have been analyzed. Based on C++builder platform, a interface desulfurization system operation optimization calculation software has been designed, it can be used to calculate the desulfurization efficiency, material, energy consumptions and put up operation optimization strategy. The calculation results when the1000MW unit is under different coals and unit loads have been compared. It is showed that when the boiler burnt the third coal (whose sulfur content is1%), Carrying out the optimal operation plan can save about3.022million yuan RMB a year. All the calculating and analyzing results above can provide certain practical operation instruction.