A Study Of Structure Strength Of Large Opening Of Marine Condenser Water Chamber And Optimization Design

Owing to the high power density and efficiency demanded by nuclear power plants a combination of large-size, cost effectiveness, as well as high safety and reliability represents a major development direction for main condensers. The water chamber construction of a main condenser with an elliptical head serving as a main body can meet the various performance requirements of a turbine unit, and has thus found wide applications. With an increase in turbine power rating and the enlargement of the size of nozzles on the head, to develop and design a structure of large-opening elliptical head which can meet the requirements in respect of both strength performance and cost effectiveness is of crucial importance for enhancing the overall performances of a turbine unit.Due to the complexity involved in the large-opening nozzle structure of an elliptical head it is very difficult to seek a theoretical solution. To date, the theoretical research results concerning the large-opening structure cannot be directly applied to practical engineering designs. With the development of finite element techniques and gradual improvement of analytic design specifications the use of stress analysis in the design of large-opening nozzle structure for an elliptical head has become a reality. On the basis of finite-element accurate calculations and by utilizing a proven elastic stress-based classification and analytic evaluation method the finite-element stress analysis has gradually become an effective means for solving the strength problem of large-opening structures.With a plane-flush and inner-protruding type nozzle reinforced structure respectively serving as an object of study a three-dimensional finite-element numerical analytic technique has been employed to perform a relatively comprehensive study of the features and mechanism of stress distribution of various reinforced structures for a dual-nozzle elliptical head construction. Moreover, the reinforcing role of such factors as the inner and external weld joints as well as the inner protruding length are analyzed and discussed. Through a contrast analysis of the reinforcing ability of various reinforcing structures proposed are reinforcing structures with relatively high effectiveness. In addition, by way of analytic design the cost-effectiveness and rationality of such structures have been evaluated.By using a resistance strain measurement method the author has effectively verified the feasibility and reliability of the finite-element calculation approach. The analysis of causes leading to errors and relevant conclusions will play a major role in guiding the design and fabrication of real and practical products.By utilizing a finite element method combined with optimization techniques the optimization design and research of a three-dimensional real-entity structure has been performed for a reinforcing structure featuring an optimum reinforcing effectiveness. The optimization analytic results have confirmed the effectiveness of the structure optimization design method in solving the design of large-opening elliptical head. Meanwhile, it also provides a scientifically practical design method and means for designing other complicated structures.