Polyhedral meshing as an innovative approach to computational domain discretization of a cyclone in a fluidized bed CLC unit

Marcin Sosnowski,Renata Gnatowska,Jaroslaw Krzywanski,W Suwała,S Łopata,J Leszczyński,M Dudek

doi:10.1051/e3sconf/20171401027

Marcin Sosnowski, Renata Gnatowska + Show 5 more

Open Access

https://doi.org/10.1051/e3sconf/20171401027

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Abstract

Chemical Looping Combustion (CLC) is a technology that allows the separation of CO2 , which is generated by the combustion of fossil fuels. The majority of process designs currently under investigation are systems of coupled fluidized beds. Advances in the development of power generation system using CLC cannot be introduced without using numerical modelling as a research tool. The primary and critical activity in numerical modelling is the computational domain discretization. It influences the numerical diffusion as well as convergence of the model and therefore the overall accuracy of the obtained results. Hence an innovative approach of computational domain discretization using polyhedral (POLY) mesh is proposed in the paper. This method reduces both the numerical diffusion of the mesh as well as the time cost of preparing the model for subsequent calculation. The major advantage of POLY mesh is that each individual cell has many neighbours, so gradients can be much better approximated in comparison to commonly-used tetrahedral (TET) mesh. POLYs are also less sensitive to stretching than TETs which results in better numerical stability of the model. Therefore detailed comparison of numerical modelling results concerning subsection of CLC system using tetrahedral and polyhedral mesh is covered in the paper.

Highlights

1.1 Simulation of fluidized bed Chemical Looping Combustion (CLC) unitThe combustion of fossil fuels in energy production and transportation is the main source of climate change
The very first issue influencing the CPU-time is the computational domain discretization, the research carried out within the confines of this paper focus on the innovative approach to discretization of a fluidized bed CLC unit
The aim of the carried out research was to investigate the possibility of applying POLY meshing as an innovative approach to computational domain discretization of a fluidized bed CLC unit

Summary

Introduction

1.1 Simulation of fluidized bed CLC unitThe combustion of fossil fuels in energy production and transportation is the main source of climate change. 1.1 Simulation of fluidized bed CLC unit. The Circulating Fluidized Bed (CFB) boilers are popular alternatives to the traditional pulverized coal boilers mostly due to decreased emission, low combustion temperature and high fuel flexibility. A key factor in the CLC performance is the Oxygen Carrier (OC), which circulates between the air reactor and fuel reactor (Fig. 1). Apart from the OC the process design is important. It consists of two reactors: the air reactor in which the OC is loaded with oxygen and the fuel reactor where the OC supplies the oxygen for fuel combustion. The system analysed within the confines of the research is based on a design presented in [2] with bubbling fluidized bed as fuel reactor and a fast fluidized bed riser as air reactor

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