Three dimensional modeling and investigation of the transient multiphase cold flow characteristics of a full loop laboratory scale CFB boiler using CFD techniques

Abstract

Optimizing the Circulating Fluidized Boiler design continues to pose huge challenges to the research community due to its complex multiphase flow characteristics. Computational Fluid Dynamics has emerged as a promising tool for modelling, analyzing and visualizing the behaviour of such entities. Part-loop modelling of the bottom bed, riser, cyclone separator etc. has been widely dealt with in literature, but serves little purpose in addressing the multifaceted real time design issues. Full-loop models with realistic boundary conditions alone can be a viable tool for the industrial designer but is rare in literature, given the complexity and computational cost involved. This dissertation attempts to develop such a model - a full-loop, 3D, transient CFD model - using standard software, approaching the industry s expectations, with the help of the guide s vast industrial experience. Based on literature studies, the Eulerian method was chosen as the most appropriate to describe multiphase flow characteristics. To validate the model, field testing will be ideal, which however was considered premature at this stage and beyond an academic s meager means. To develop a confidence in the model and to test its reliability and versatility, a variety of approaches have been attempted including Input-Output Analysis, Experimental Verification on a scaled-down model, specially fabricated for this purpose and supplementary mathematical models. newline newline newline