Study On The Uniformity Of Gas Solid Mixing In Sodium Based Dry Flue Gas Desulfurization

Sodium based dry desulfurization is a process where the desulfurizer baking soda is sprayed into the main flue gas pipeline through a branch pipe and mixed with the flue gas to undergo a chemical reaction to achieve desulfurization.The mixing pipe section is the core component of the flue gas desulfurization process.However,the existing mixing pipe section has a simple structure and uneven mixing of flue gas and baking soda within the pipe section,resulting in low desulfurization efficiency and high consumption of baking soda.Therefore,this article proposes a method of incorporating a turbulent flow structure in the mixing pipe section to study the problem of uneven gas-solid mixing in the pipe section,which has significant research significance for improving desulfurization efficiency and saving production costs.Based on the gas-solid two-phase flow theory,the transportation mode and force situation of desulfurizer particles in the main pipeline were analyzed,and a gas-solid twophase flow control equation was established.By analyzing the advantages and disadvantages of turbulence theory and different turbulence models,the Standard kepsilon model was selected as the turbulence model of this article,and a method for calculating the uniformity of gas-solid mixing was proposed.A three-dimensional gas-solid mixing numerical model was established and calculated for the expansion of the mixing pipe section,different built-in turbulence devices,and different desulfurization agent branch nozzle structures.The velocity,pressure,turbulent kinetic energy changes of the flue gas during the sodium based dry flue gas desulfurization process,as well as the distribution of desulfurization agent particles,were obtained.The calculation results show that the desulfurization efficiency is positively correlated with turbulent kinetic energy and pressure loss,and the uniformity of gas-solid mixing increases with the increase of turbulent kinetic energy and pressure loss.By comparing the concentration standard deviation of each model at 11.5m section under the same operating conditions,the optimal model is the fan baffle and cross baffle turbulence model.This model has good gas-solid uniformity and desulfurization efficiency has increased by 50% compared to the on-site model.Using the principle of similarity,a sodium based dry desulfurization experimental device was designed,and physical simulation experiments were conducted on the presence or absence of built-in turbulence structures in the mixing pipe section.The numerical calculation results were verified,and experimental results that were basically consistent with the numerical calculation results were obtained.It was confirmed that the sodium based dry desulfurization model with built-in turbulence devices can significantly improve desulfurization efficiency and reduce production costs.