Optimization of Slurry PH Value for Limestone Wet Desulfurization Technology
Based on limestone wet desulfurization spray scrubber technology, this paper explicitly introduces the ionization process of water in slurry, deduces controlled range of slurry PH value and equation of slurry PH value in slurry droplet by analyzing the main origin of H+ and OH-, and other factors that influence ionization balance of water in slurry, provides theories for simulation of slurry PH value and optimization in practical operation. Besides, it concludes the reasonable range of slurry PH value by analyzing various factors such as increasing SO2 removal efficiency, decreasing operation cost, dissolution of CaCO3, oxidation of SO32- andHSO3-, and relationship of slurry PH values between slurry surface and the undersurface, provides reference for optimization of slurry PH value in practice. Finally, an optimization experiment of slurry PH value is designed for#11FGD in Taiyuan co-generation power plant, and the slurry PH value is optimized effectively.
Operation strategy optimization of desulfurization system based on data mining
Abstract Desulfurization systems in coal-fired power stations often suffer the problem of high operating costs caused by a rule-of-thumb control strategy, which implies great potential for optimization of the operation. Due to the complex desulfurization mechanism, frequently fluctuating unit load, and severe disturbance, it is challenging to determine the optimal operating parameters based on the traditional mechanistic models, and the operating parameters are closely related to the operational efficiency of the flue gas desulfurization system. In this paper, an operation strategy optimization method for the desulfurization process is proposed based on a data mining framework, which is able to determine online the optimal operating parameter settings from a large amount of historical data. First, Principal Component Analysis (PCA) is used to reduce data redundancy by mapping the data into a new vector space. Based on the new vector space, an enhanced fuzzy C-means clustering (Enhanced-FCM) is developed to cluster the historical data into groups sharing similar characteristics. Taking sulfur dioxide emission concentration as a constraint condition, the system is optimized with economic benefits and desulfurization efficiency as the objective function. When performing optimization, the group that current operating conditions belong to is determined first, then the operating parameters of the best performance are searched within the group and provided as the optimization results. The method is validated and tested based on the data from a wet flue gas desulfurization (WFGD) system of a 1000 MWe supercritical coal-fired power plant in China. The results indicate that the proposed operation strategy can appropriately obtain operating parameter settings at different conditions, and effectively reduce the desulfurization cost under the constraint of meeting emission requirements.
SO2 absorption in a bubbling reactor using limestone suspensions
Abstract In the present work attention was focused on a wet flue gas desulfurization process using limestone suspensions, which is the most common method used to reduce SO 2 emissions from power plant exhaust gases. The SO 2 absorption rate was measured varying both the SO 2 concentration in the gas phase and the limestone concentration in the suspension. The experiments were performed by bubbling mixtures of sulfur dioxide and nitrogen in the continuous limestone aqueous suspension. The absorption phenomenon was studied by making use of the film theory to describe the liquid-side mass transfer. It was assumed that the liquid-phase diffusional resistance is concentrated in a layer the thickness of which depends on fluid dynamics, but which is independent of the nature of the reactions taking place. The equations considered by the model describe conditions of thermodynamic equilibrium as well as material and electrical balances. Furthermore, they take into account the effect of the gradient of the electric potential of diffusion on the diffusive transport of ions and molecules in the film surrounding the gas-liquid interface. The SO 2 absorption rate and the limestone dissolution rate experimentally determined were used to integrate the model equations, yielding the value of the film thickness, and allowing the determination of the concentration profiles of the different species in the liquid film and of the enhancement factor for chemical absorption. Consistency between model and experimental results, on the basis of the hypothesis of the model, was found.