Three-dimensional modeling of biomass fuel flow in a circulating fluidized bed furnace with an experimentally derived momentum exchange model

Nikku, Markku; Myöhänen, Kari; Ritvanen, Jouni; Hyppänen, Timo; Lyytikäinen, Marko

doi:10.1016/j.cherd.2016.09.023

Cited by 15 publications

(8 citation statements)

References 49 publications

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“…There are many different approaches in modeling fluidized beds that differ in the level of detail and applicability. The most detailed methods solve the movement of the individual particles and are limited to small scale applications, namely the discrete element method (Jalali et al, 2013;Lu et al, 2015), while less detailed methods, such as Eulerian-Eulerian (Nikku et al, 2016;Shah et al, 2015a) or Eulerian-Lagrangian approach with particle grouping methods (Adamczyk et al, 2014a(Adamczyk et al, , 2014bNikolopoulos et al, 2017), are able to simulate even large industrial applications. In an ideal case, where computational power would be abundant, methods such as direct numerical simulation (DNS) and discrete element method (DEM) would be used to solve the different flow related quantities with minimal amount of numerical modeling involved in the simulations.…”

Section: Introductionmentioning

confidence: 99%

Comparison of solid phase closure models in Eulerian-Eulerian simulations of a circulating fluidized bed riser

Nikku

Daikeler

Stroh

et al. 2019

Chemical Engineering Science

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In this work, computational fluid dynamics with Eulerian-Eulerian modeling approach is used in the investigation of the effect of the solid phase closure models on the hydrodynamics of a circulating fluidized bed riser. The studied models are the kinetic theory of granular flow and the powder modulus model. Computational performance and model prediction accuracy are investigated by performing transient simulations for three different cases and for different mesh sizes. The modeling results are compared with measured vertical pressure profile, external circulation mass flow rates, and particle velocity and concentration profiles obtained from a laboratory scale circulating fluidized bed unit. Additionally the computational times are compared to estimate the computational performance and to investigate if a simpler set of closures is computationally more affordable. The results indicate that both closure models can give good predictions for some quantities, while lacking in other quantities. The results indicate that the closure models for the solid phase have a noticeable effect on the model predictions, such as the vertical pressure profile and external circulation rate of the particles.

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Section: Introductionmentioning

confidence: 99%

Comparison of solid phase closure models in Eulerian-Eulerian simulations of a circulating fluidized bed riser

Nikku

Daikeler

Stroh

et al. 2019

Chemical Engineering Science

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“…Figure 1 illustrates the mesh of the incinerator with the relevant inlets and outlets. The utilized cell sizes are similar to previous simulations with the same in-house CFB furnace model (Nikku et al 2014, Nikku et al 2016 and the model frame was found to be insensitive to mesh size (Nikku et al 2014). Both the MSW and coal are fed to the incinerator from the front wall with boundary conditions for fuel inlet velocity [vx,vy,vz] of [0,1,-1] m/s and fuel dispersion coefficients were 0.2 m/s 2 and 0.05 m/s 2 for horizontal and vertical directions, respectively (Nikku et al 2014).…”

Section: Simulation Casesmentioning

confidence: 99%

“…For large CFB furnaces and incinerators, time-dependent computational fluid dynamics (CFD) simulations are often too time consuming for engineering applications, and a common solution is to perform steady-state simulation to represent time-averaged conditions of the incinerator. Previously, this kind of modeling studies on CFB furnaces have been published utilizing an in-house three-dimensional CFB model frame to study combustion, gasification, and sorbent reactions in commercial and pilot scale CFB units (Hyppänen et al 1991, Lyytikäinen et al 2011, Nikku et al 2014, Nikku et al 2016. While many works are found in the literature dealing with different aspects of MSW incineration (waste production, chemical properties, emissions, enviromental impacts, etc.…”

Section: Introductionmentioning

confidence: 99%

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Three-Dimensional Modeling of a Chinese Circulating Fluidized Bed Incinerator Firing Municipal Solid Waste

Nikku¹,

Zhan²,

Myöhänen³

et al. 2021

j solid waste technol mngmnt

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Currently waste incineration is a widely used method of waste management in China. Effective incineration requires understanding and tools to analyze the incineration process leading to good incinerator performance and efficiency as well as lower emissions. In this work, a Chinese circulating fluidized bed (CFB) incinerator firing municipal solid waste (MSW) and coal is modeled with a three-dimensional CFB furnace model to evaluate the incineration process. First, the modeling results are verified with measurement data from the incinerator. Then, the furnace model is applied in the simulation of a case with more dry MSW without coal. The objective of the research is to provide insight and increase understanding of the MSW incineration process. The simulation case of MSW with the lower moisture content highlights the possible reductions of fossil carbon emissions associated with the utilization of coal. To achieve this, a moderate reduction in the moisture content of MSW is required. A comparison between the MSW and coal versus only the MSW shows minor differences in the performance of the incinerator. Utilization of modeling in incinerator studies can aid in development of more efficient CFB incinerators, improving the waste management and reducing the utilization of fossil coal.

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“…Numerical modeling is a cheap alternative to test new concepts and designs, compared to building prototypes, especially of large and expensive devices. Considering circulating fluidized bed (CFB) reactors and furnaces, where multiphase flow, heat transfer, and thermochemical reactions can occur simultaneously in various time‐ and length scales with strong coupling, detailed and extensive measurements are hard and very time consuming to perform 1 . Fluidized beds are multiphase systems where particulate matter called the bed material is set to a fluidlike state by a fluid flow, and the fluidization regime of the system depends primarily on the fluid flow rate, reactor geometry, and fluid and bed material properties.…”

Section: Introductionmentioning

confidence: 99%

Effect of software implementation on the result of computational fluid dynamics simulation of circulating fluidized bed risers

Nikku

Niemi

Kallio

et al. 2021

Engineering Reports

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While in scientific literature much focus is directed toward model validation, comparison, and even parametric investigations on individual model parameters, the possible effects of the used computational fluid dynamics (CFD) software on the results are largely neglected. In this article, CFD modeling of circulating fluidized beds (CFB) are performed with Ansys Fluent and OpenFOAM to investigate the effect of software implementation on the simulation results. Transient Eulerian–Eulerian simulations are performed of two different laboratory‐scale CFB cold models in turbulent and circulating fluidized bed conditions. The same mesh and as identical models and settings as possible are utilized on both software. The obtained time‐average profiles of pressure, velocity, and solids volume fraction are compared between the software and with available measurements. A difference in the granular energy equation was identified between the software, and a modification was made to achieve the same formulation. The effect of boundary conditions was also investigated. It was found that depending on the case, the software could have a notable effect on the results. These differences are found especially in particle distribution, visible in the vertical pressure and solids volume fraction profiles as well as in external circulation mass flow rates.

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Three-dimensional modeling of biomass fuel flow in a circulating fluidized bed furnace with an experimentally derived momentum exchange model

Cited by 15 publications

References 49 publications

Comparison of solid phase closure models in Eulerian-Eulerian simulations of a circulating fluidized bed riser

Comparison of solid phase closure models in Eulerian-Eulerian simulations of a circulating fluidized bed riser

Three-Dimensional Modeling of a Chinese Circulating Fluidized Bed Incinerator Firing Municipal Solid Waste

Effect of software implementation on the result of computational fluid dynamics simulation of circulating fluidized bed risers

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