Numerical Simulation And Structural Optimization Of Gas-Liquid Flow Field In The Spray Tower Of Flue Gas Ammonia Desulfurization

As a harmful gas,sulfur dioxide（SO₂）is widely present in flue gas emissions.In order to control SO₂ emissions,continuously advanced flue gas desulfurization technology is still a hot research topic at home and abroad.Non-empty tower efficiency enhancement technology has many unique advantages and has become the most commonly adopted desulfurization efficiency method under the current ultra-low emission standards,especially the development and application of new rectifier internal components.Through a combination of numerical simulation and theoretical analysis,the flow field and pressure field distribution of an empty tower and towers equipped with different rectifying internals were discussed in this paper.Based on the ammonia desulfurization tower process and the on-site device parameters of a 480 t/h coal-fired boiler flue gas,the CFD-DPM model of Euler-Lagrangian method was used to develop a mathematical model.This model is suitable for non-empty tower efficiency enhancement of ammonia desulfurization spray tower and its validation is verified.Using this model,the flow field and pressure field in the tower were studied numerically.Firstly,a numerical study of gas-liquid two-phase flow was carried out on the empty tower,and it was found that there were serious problems such as flue gas escaped from the side wall of the tower,uneven gas velocity distribution,and large tower resistance.In view of the problems existing in the empty spray tower,the twin-tangential annular flow gas distributor and the two-line vane gas distributor were introduced into the ammonia desulfurization spray tower for the first time.At the same time,combining the respective characteristics of the two types of distributors,an innovative radial blade gas distributor was proposed,and the enhancement effects of three distributors were studied.Among them,the twin-tangential annular flow gas distributor has a better optimization effect on the problem of flue gas escape,while the radial blade gas distributor has the smallest resistance loss to the flue gas and its gas velocity distribution unevenness is always at a relatively lowest level.Moreover,its unevenness value of 1 m below each spray layer is reduced by 15.9%,14.0%,and 14.0%respectively compared with that of the empty tower.This means that the enhancement effect of the radial blade gas distributor is the greatest.In this paper,the structural parameters of the radial blade gas distributor were also optimized.For the ammonia desulfurization spray tower involved in this study,in terms of reducing the pressure loss in the tower,it was recommended to increase the height of radial blades.At the same time,the radial distance from the blade outlet to the tower wall should be 2189.5 mm,and the number of blades should be 24.In terms of improving the uniformity of gas velocity,it was recommended to reduce the radial distance from the blade outlet to the tower wall and increase the height and number of blades.