面向DCS优化控制的氨法脱硫过程模拟

Simulation of ammonia desulfurization process for DCS optimization control

为了实现氨法脱硫过程优化控制,建立了脱硫塔喷淋脱硫过程气液流动与化学反应耦合的三维数理模型,气相场采用k-ε湍流模型,喷淋液采用颗粒轨道模型,SO_2的吸收基于双膜理论.以2个单塔烟气处理量750 000 m^3/h的喷淋塔为对象,通过数值模拟考察了烟气流速、入口烟气SO_2浓度、液气比对脱硫效率的影响.研究结果显示:随着烟气流速及入口SO_2浓度增大、液气比的降低,脱硫效率降低.在此基础上,结合现场运行数据,构建了DCS优化控制函数,采用Visual C++与M ATLAB混合编程开发了流场可视化模块,并将其嵌入DCS系统中.在360M W热电厂烟气脱硫系统上,实现了氨法脱硫过程数据的实时显示分析和优化控制,确保了脱硫效率在95%~99%之间.

A three-dimensional numerical model for a desulfurization tow er gas-liquid flow coupling with chemical reaction in mass transfer of the ammonia desulfurization process was established to achieve the optimization control. The k-ε turbulence model was used for the gas phase trajectories were calculated by a discrete particle model and the two-film theory absorption model was used for the absorption of SO2. The influences of gas velocity,the initial concentration of SO2 and liquid-gas ratio on the desulfurization efficiency（ η） of sulfur dioxide were studied by the numerical simulation on a model of two spray tow er and single tow er flue gas was 750 000 m3/h. 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（ distributed control system） optimization control function is established combined with the field operation data based on the numerical simulation result. The flow field visualization module is developed and loaded to the DCS of pow er plant combined with the optimization control function by the using of Visual C ＋ ＋ and MATLAB mixed programming. The real-time analysis on data and DCS optimization control is realized in the flue gas desulfurization system of 360 MW thermal pow er plant and desulfurization efficiencies are ensured by 95% to 99%.