Study On The Arrangement Of Steam And Water Inlet Pipe In The Separator Of Boiler Start-up System

A steam separator is one of core component used in the start-up system of thermo-power boiler,and its separation performance and structural strength affect the safety and efficiency of boilers.The reinforcement of the inclined openings located in the inlet of steam and water is of extreme importance,when it comes to the design of steam separators.How to design those opening is a procedure beyond the scope specified in our existing pressure vessel codes and there are also no proper speculations to follow.When constructed in boiler industries,these inclined openings are treated as orthogonal ones based on equal-area reinforcement method,which is not sound theoretically.In the arrangement of steam water inlet pipes,almost all steam water separators adopt the method of six pipe nozzles arranged in the same layer,so the inter-influence among those opening is severe.Within this paper,the finite element analysis software ANSYS is utilized to study the strength of the inclined holes of the steam water separators.Moreover,ANSYS and computational fluid dynamics software CFX are applied to investigate the strength and separation performance of inlet pipes with different arrangement modes.Also,the finite element method(FEM)is used to compare the stresses calculated using the plane expansion model of the inclined opening holes,the model of equivalent elliptical holes,and the method of equivalent circular holes separately.Still,comparison of outcomes obtained between the structure of inclined openings and the one of equivalent orthogonal openings is carried out with the help of three dimensional finite element models.Results show that this oblique opening method used currently in engineering fields is conservative.When designing the inclined openings of steam water separators,the limit load analysis approach is more reasonable than the linear elastic method.Varying the arrangement of steam water inlet pipes leads to different layout schemes,and the strength and separation performance of those schemes are studied using ANSYS and CFX.Outcomes present that the single layer arrangement is better than the double layer model,and when the single layer model is adopted,it turns out that the number of nozzles has little influence of the strength of separators,while significantly affects their efficiency.Furthermore,three,four,and six nozzles single layer arrangements experience close efficiency,and the separation efficiency of the double layer arrangement and the two nozzles single layer model is obviously lower than that of other layouts.Comprehensively considering factors such as strength,separation performance,material utilization,and manufacturing,it is recommended to adopt the practice of three or four nozzles single layer arrangement.