Structure Analysis And Optimum Design Of FRP Flue Duct

Because the environmental requirements is increasingly strict, the flue gas from thermal power plants must be desulfurized before discharge. The current technology used widely for this purpose is wet desulfurization. As an advanced environmental protection technology in power industry in the world, the "combined usage of stack and tower" technology has many advantages. It is capable of uplifting the clean flue gas effectively, promoting the diffusion of pollutants, lowering ground concentrations of pollutants, and saving construction costs. The design of flue duct is an important part of this technology. Because FRP materials are flexible in design to achieve desirable properties. A suitable design of FRP flue duct can meet the requirements mentioned above, and at the same time it can possess good characteristics including good chemical resistance, low thermal conductivity rate, long service life, low cost, light weight, and large span capability.This paper discuss the FRP flue duct design applied in a new 2 x 300MW project using the "combined usage of stack and tower" technology. The finite element analysis software ANSYS is used as the technology platform to study the overall structure of FRP flue stability and static analysis, as well as to evaluate the performance of the flue. In this paper, the influence of different factors on the structural strength and stability were analyzed. The design of the flue pipe body was optimized with variable thickness along the duct axis.The main content of this paper is as follows:1. The finite element analysis uses APDL (Adapative Parametric Developing Language) to establish the finite element model of FRP flue and input all the material parameter information. Five working loadcases were investigaed, including static strength analysis and stability analysis under wind and external pressure. The finite element analysis results reveal that the deformation, stress and strain of the FRP flue under the five loadcases all satisfy the design requirements. Stress concentration location occurs at the supporting positions. Stability analysis of the FRP flue ducts also meet stability requirements. Besides, the site of instability and failure was positioned. 2. No.2 steel support was analyzed in detail for different fixation methods. The analysis results show that all the three fixed methods satisfy the static strength and stability requirements. The single frame fixation method is beneficial to both the duct body and the steel supports for thermal stresses can be released using this method. In one word, the single frame fixation method is superior to the double fixation one.3. Models with twelve spans were analyzed. And the structure properties of the FRP flue ducts with different spans were discussed based on these results.4. The structure design of FRP flue duct was optimized by using duct thickness as design variables. Based on the calculation of stress distribution of equal thickness, the variable thickness design of each segment can be determined and checked. The strength and stability requirements were all met by the optimal design achieved. And weight of the pipe body is reduced by 17.53%.