Modeling And Engineering Experiment Of Ammonia Desulfurization Process In Power Plant

The emission of sulfur dioxide in flue gas increased the air pollution in the city,and ammonia desulfurization was widely used in the field of desulfurization of power plant as a high efficiency and low pollution desulfurization technology.The running process of ammonia desulphurization system mainly rely on manual spraying ammonia in YangZi petrochemical thermal power plantoperation to ensure the SO₂concentration of export,there is no automatic optimization control system of investment,so that the timely and precise adjustment of the amount of ammonia can not be realized.Recently,the operating parameters of the system are mainly dependent on experience,lacking of guidance of theoretical model,Therefore,it is an important measure to establish the optimal control function of DCS in the process of ammonia desulfurization.The numerical simulation technology and advanced control technology was combined to carry out engineering test,numerical simulation and optimization control system development for ammonia desulfurization process.In order to achieve the optimization control,the model of two spray tower whose single tower flue gas was 750000m³/h in YangZi petrochemical thermal power plant was established,and a three-dimensional numerical model of a desulfurization tower gas-liquid flow coupling with chemical reaction in mass transfer of the ammonia desulfurization process was set up based on CFD-DPM method.The k-?turbulence model was used for the gas phase;trajectories were calculated by discrete particle model;and the two-film theory absorption model for the absorption of SO₂.The desulfurization process engineering test was carried out on 1#and 2#desulfurization tower of YangZi petrochemical thermal power plant to provide experimental basis for CFD modeling and DCS optimization control function.On the basis of the numerical simulation,the flow type,velocity,temperature and concentration of the gas flow in the desulfurization tower were investigated.The influence of gas velocity,the initial concentration of SO₂ and liquid-gas ratio on desulfurization efficiency were investigated.Research results show that the desulfurization efficiency decreases with the increase of the gas velocity and the initial concentration of SO₂,or with the decrease of liquid-gas ratio.The DCS optimization control function was constructed combining with the field operation data.Based on the numerical simulation and engineering test results,the flow field visualization module was developed and loaded to the DCS of power plant combined with the optimization control function by the using of Visual C++and MATLAB mixed programming.The real-time analysis of data and DCS optimization control was realized on the flue gas desulfurization system of 360MW thermal power plant and desulfurization efficiency was ensured between 95%and 99%.The running results show that the automatic adjustment and control of ammonia flow were realized,and ensure that the desulfurization efficiency was between 95%⁹9%,pH within 5.0⁶.0,and saving ammonia consumption 5%¹0%.