Numerical Experiment And Design Optimization Of Miniaturization Of Ship Desulfurization Scrubber Structure

The International Maritime Organization has established strict standards for ship SOx emission problem.If it fails to meet the standards,the ships produced and operated in China will be prohibited from sailing on the high seas,so it is extremely urgent to develop ship SOx emission control technology.Exhaust gas desulfurization technology has the advantages of wide application range and low operating cost and has received extensive attention from the shipbuilding industry.However,the limited space of the ship poses a huge challenge to the design of the scrubber which is the core component of the desulfurization system.The scrubber designed according to the experience of land engineering is difficult to adapt to the narrow space of the ship.Therefore,it is necessary to carry out miniaturization design research of the scrubber.In this paper,the miniaturation design research of the ship desulphurzation scrubber is supported by the 77000 kg/h ship eahaust gas desulphurization project of Guangzhou Shipyard International Co.Ltd.In this paper,the ship desulphurization scrubber designed by Guangzhou Shipyard International Co.Ltd based on the land experience is taken as the prototype.First,the numerical simulation technology is used to study the influence of structural parameters of desulphurization scrubber on the desulfurization efficiency.Based on the results of simulation,an optimization method based on support vector machine and genetic algorithm(SVM-GA)is established and the miniaturization results were verified by experiments.Finally,a complete enginnering design was formed.In this paper,the structural model of marine seawater desulfurization scrubber is constructed.The numerical simulation method of CFD-DPM couping with chemical reaction is adopted.The gas field uses k-ε double equation turbulence model and the spray droplet adopts discrete phase model.Based on the two-film theory,a mass transfer model for SO2 absorption in the tower was established.In the solution process,the gas phase field is solved in the Euler coordinate system,and the discrete phase is solved in the Lagrangian coordinate system.The characteristics of droplet trajectory,gas flow and SO2 concentration distribution in the scrubber were obtained,and the effects of diameter,absorption area height,inlet flue gas angle,number of spray layers and liquid-gas ratio on desulfurization efficiency were investigated and get the results as follows:as the decrease of scrubber diameter D1,the desulphurization efficiency decreases;as the height of absorption area H2 decrease,the desulphurization efficiency decreases;as the inlet flue angle θ increases,the desulfurization efficiency first increases and then decreases;as the number of spray layers N increases,the desulfurization efficiency increases.Based on the numerical simulation data,the relationship model between desulfurization scrubber structure and working condition parameters and desulfurization efficiency was constructed by SVM,and the mean square error of the model is only 2.9×10-6.After the combination of GA algorithm and SVM,take the desulfurization efficiency as the standard and the miniaturization of desulfurization scrubber size as the target.Then the structural parameters of the desulfurization scrubber are optimized,and the minimum desulfurization scrubber size is obtained with the requirement of desulfurization efficiency satisfying.Compared with the existing design,the volume reduced by 30%,and the design was successfully applied to the engineering project of Guangzhou Shipyard International Co.Ltd.Besides,this method can not only be used to deal with the miniaturization problems of desulphurization scrubber,but also solve other complicated optimization problems under different constraints.In addition,in order to supplement and improve the research results,the miniaturization method was validated by experiments.Finally,based on the results of the previous study combined with the actual needs of the project,a desulfurization system for treating 77000 kg/h flue gas was designed,including the process route and the design of each subsystem.The design calculation and selection for the core components were also completed.