A numerical investigation into the effect of angular particle shape on blast furnace burden topography and percolation using a GPU solved discrete element model
Introduction
Blast furnaces (BFs) are widely used as a continuous smelting process in the steel industry (Iron and Steel Institute of Japan, 2009, Ghosk, 2008). In this process, successive layers of coke and iron ore are continuously charged from the top of a blast furnace, with additional coke, ore and limestone, while air is continuously injected into the lower section of the furnace through the tuyere, so that carbon (C) from the coke reacts with oxygen (O) in the haematite (Fe2O3) and magnetite (Fe3O4) in the iron ore (Biswas, 1981). This produces off-gas in the form of CO (incomplete combustion) and CO2 (complete combustion), and the main product of carbon contaminated iron ore or as pig iron which is tapped from the bottom to be converted into steel. Around 60% of the entire steel industry energy is consumed by BFs that are also responsible for 90% emissions (Fujita, 2010). Energy consumption in a blast furnace operation depends on (i) percolation uniformity of interstitial gas flow through the packed-bed to enhance efficient heat and mass transfer, and (ii) greater combustion surface area to facilitate complete combustion. Hence, the gas flow distribution and the furnace performance is directly influenced by the burden topography inside a BF (Kuang et al., 2017).
As the burden topography is largely dictated by the particle properties (e.g. shape and size) and the charging process (Dahlstedt et al., 1999, Dudinski and Gammel, 2006), various innovative charging systems were developed, including the bell-less top (BLT) charging system (see Fig. 1(b)) and the Gimbal charging system (SIMETALCIS Gimbal Top) depicted in Fig. 1(c), to offer more charging control than the one and two bell (with a lower and upper bell as depicted in Fig. 1(a)) systems prevailed until 1972. In order to explore the charging performance of these charging systems, many experimental studies on charging behaviour and burden topography were performed (Takahashi and Komatsu, 1993, Guo and Chen, 2004, Baath et al., 2008, Dahlstedt et al., 1999), so were numerous discrete element method (DEM) simulations, especially on BLT charging and burden distribution using mono-sized (Ariyama et al., 2014, Hou et al., 2017, Qiu et al., 2017, Xu et al., 2018, Peters et al., 2018), polydispersed (Mio et al., 2007, Mio et al., 2009, Zhang et al., 2014, Ariyama et al., 2014, Terui et al., 2017), and clumped spherical (up to a dozen spherical particles) particle systems (Yu and Saxen, 2014, Mitra, 2016, Ariyama et al., 2014, Natsui et al., 2009, Terui et al., 2017), as well as coupled DEM with computational fluid dynamics (DEM-CFD) (Hou et al., 2017, Baniasadi et al., 2018).
From numerical simulations incorporating of fluid and thermofluid interactions with the particles, the following five domains of particle flow inside a BF were identified: (i) quasi-stagnant zone, (ii) wall shear zone, (iii) deflecting flow zone, (iv) converging flow zone and (v) transitional flow zone. Distinct mechanical interactions, i.e. force chain networks (Nouchi et al., 2009), and spatial velocity profiles were observed in these flow regimes (Qiu et al., 2017). Previous studies found that the particle size distribution is an important factor in optimising the uniformity of charge layers and in suppressing segregation for spherical particle systems (Terui et al., 2017). The furnace should be charged in such a way that the coarser and finer particles are distributed appropriately on the burden surface to control the burden distribution, so that the uniform percolation of gas through the bed can be achieved as well as the lining of the BF protected. As a consequence, smaller sized sinter should be discharged in the periphery area for protecting the lining and preventing excessive heat losses, and particles of large sizes in the central area to form a strong central gas flow (Ueda and Natsui, 2010, Shen, 2014). In addition, the mean size of the sinter should gradually increase from the periphery to the centre, in order to attain an increasing gas distribution from the periphery area to the central area (a weak gas flow at the wall area with lower porosity and a strong gas flow in the central line of furnace with higher porosity). Creating a thin iron-bearing material layer at the periphery with a small quantity of small size sinters leads to a thin cohesive zone at the lower part of furnace and a reduced pressure drop of whole furnace. Although the benefit of the controlled burden distribution (i.e. burden of a controlled microstructure achieved with an optimal distribution of feed materials) has been anticipated, it is a challenging task to realise it in practice. Hence, only the height of the burden layer is currently controlled in the blast furnace through the control of the mass flow rate in a rotating chute discharging system.
In addition, the importance of particle shape on the burden topography and the gas dynamics through the particle bed was also highlighted (Hilton and Cleary, 2012, International, 2012, Xu, 2006, Mio et al., 2017). Nevertheless, in previous simulations the particle shape was generally modelled using spheres or clumped spheres, and particle angularity was normally ignored. Moreover, numerical studies with shape polydispersity remains scarce (Yu and Saxen, 2014, Mitra, 2016, Ariyama et al., 2014), so the influence of particle angularity on the charging behaviour and burden formation is still poorly understood. Therefore, this study aims to investigate the influence of angularity for polyhedral particles in the layering and stability of particle bed during charging of a BF. In particular, the impact of shape polydispersity and size polydispersity of the coke and iron ore on the burden formation will be explored. Our hypothesis is that only through appropriate models can a thorough understanding be obtained for the charging behaviour as well as burden formation and descent.
Section snippets
Discrete element method
Granular media (GM) is only second to water as the most manipulated substances on the planet (de Gennes, 1999), and is encountered in almost all industries. The understanding of the physical behaviour of GM is critical in design and operation of process equipment as it exhibits various complex phenomena such as percolation, elutriation, agglomeration and flow-induced mechanisms (Scott and Bridgwater, 1975, Pathak et al., 2017). Thus a number of computational approaches were developed (Khakhar
Experimental validation
BlazeDEM-GPU (Govender et al., 2016) has been validated for a number of applications (Govender et al., 2014, Govender et al., 2015, Govender et al., 2015, Govender et al., 2018, Wilke et al., 2016, Govender et al., 2018, Govender et al., 2018) and also used by a increasing number of users in the Americas, Europe, UK, Africa, Asia and Australia. In this study we further verify that the code does indeed capture the macroscopic behaviour of charging for the choice of parameters used in this study.
Modelling assumptions
Fig. 12 depicts the geometrical setup which consists of a filling silo (Part 1) where particles are generated, a hopper (Part 2) through which the particles are discharged onto a chute, rotating at 10 rpm, with a fixed inclination of 60 degrees similar to Xu et al. (2011), denoted as Part 4, filling a cylindrical throat (Part 3). A typical blast furnace has a diameter of around 10 m with a typical maximum particle size of 100 mm, giving a ratio of 100:1 (ignoring fines (Zhang et al., 2014))
Conclusions
In this study we first validated the simulated polyhedral charge layering against experimental charge layering results. This was followed by a study on the effect of shape polydispersity and size polydispersity of polyhedral particle systems on the burden topography. It was found that shape polydispersity mainly influenced the burden topography of the burden, whereas the size polydispersity influenced the inter-layer percolation due to the better flowability of the size polydispersed particle
Conflict of interest
The authors declared that there is no conflict of interest.
Acknowledgments
This work was supported by the MARIE Sklodowska-CURIE Individual Fellowships with acronym DECRON, funded through the People Programme (MARIE Sklodowska-CURIE Actions) of the European Union’s H2020 under REA grant agreement No. 747963. We gratefully acknowledge the support of the NVIDIA Corporation with the donation of the Titan X Pascal GPU used for this research. The financial support of the National Research Foundation (NRF) of South Africa is acknowledged.
References (94)
- et al.
Microstructural blending of coal to enhance flowability
Powder Technol.
(2000) - et al.
Three-dimensional particle shape descriptors for computer simulation of non-spherical particulate assemblies
Adv. Powder Technol.
(2004) - et al.
Using the discrete element method to assess the mixing of polydisperse solid particles in a rotary drum
Particuology
(2016) - et al.
Discrete element simulation of particle mixing and segregation in a tetrapodal blender
Comput. Chem. Eng.
(2014) - et al.
Numerical study of the mixing efficiency of a ribbon mixer using the discrete element method
Powder Technol.
(2016) - et al.
A new contact detection algorithm for three-dimensional non-spherical particles
Powder Technol.
(2013) Particulate mixing in a plough share mixer using DEM with realistic shaped particles
Powder Technol.
(2013)- et al.
How well do discrete element granular flow models capture the essentials of mixing processes?
Appl. Math. Model.
(1998) - et al.
On the numerical modeling of granular material flows via the particle finite element method (pfem)
Int. J. Solids Struct.
(2015) - et al.
Energy-conserving contact interaction models for arbitrarily shaped discrete elements
Comput. Meth. Appl. Mech. Eng.
(2012)
Collision detection of convex polyhedra on the NVIDIA GPU architecture for the discrete element method
Appl. Math. Comput.
Discrete element simulation of mill charge in 3D using the BLAZE-DEM GPU framework
Min. Eng.
Blaze-demgpu: Modular high performance DEM framework for the GPU architecture
SoftwareX
A study of shape non-uniformity and poly-dispersity in hopper discharge of spherical and polyhedral particle systems using the Blaze-DEM GPU code
Appl. Math. Comput.
Effect of particle shape in grinding mills using a GPU based DEM code
Min. Eng.
Large-scale GPU based DEM modeling of mixing using irregularly shaped particles
Adv. Powder Technol.
Raceway formation in laterally gas-driven particle beds
Chem. Eng. Sci.
Comparison of the multi-sphere and polyhedral approach to simulate non-spherical particles within the discrete element method
Powder Technol.
Dem-based virtual experimental blast furnace: a quasi-steady state model
Powder Technol.
Continuum model of mixing and size segregation in a rotating cylinder: concentration-flow coupling and streak formation
Powder Technol.
Evaluation of contact force models for discrete modelling of ellipsoidal particles
Chem. Eng. Sci.
Discrete element simulations of a high-shear mixer
Adv. Powder Technol.
Towards realistic and interactive sand simulation: a GPU-based framework
Powder Technol.
Experimental validation of polyhedral discrete element model
Powder Technol.
Simulation of charge motion in ball mills. Part 1: Experimental verifications
Int. J. Mineral Process
Simulation of burden distribution and charging in an ironmaking blast furnace
IFAC-PapersOnLine
Effect of particle shape on flow in discrete element method simulation of a rotary batch seed coater
Powder Technol.
Numerical study of particle mixing in a lab-scale screw mixer using the discrete element method
Powder Technol.
Large-scale powder mixer simulations using massively parallel GPU architectures
Chem. Eng. Sci.
Large-scale powder mixer simulations using massively parallel GPU architectures
Chem. Eng. Sci.
Discrete element simulation for the evaluation of solid mixing in an industrial blender
Chem. Eng. J.
Model study of the effect of bird’s nest on transport phenomena in the raceway of an ironmaking blast furnace
Min. Eng.
3d simulation of charge motion in tumbling mills by the discrete element method
Powder Technol.
LIGGGHTS and EDEM application on charging system of ironmaking blast furnace
Adv. Powder Technol.
Quasi-real-time simulation of rotating drum using discrete element method with parallel GPU computing
Particuology
Circumferential burden distribution behaviors at bell-less top blast furnace with parallel type hoppers
Appl. Math. Model.
Quantitative comparison of binary particle mass and size segregation between serial and parallel type hoppers of blast furnace bell-less top charging system
Powder Technol.
Segregation behavior of particles in a top hopper of a blast furnace
Powder Technol.
A fast scalable implementation of the two-dimensional triangular Discrete Element Method on the GPU platform
Adv. Eng. Software
Simulation of particle flow in a bell-less type charging system of a blast furnace using the discrete element method
Particuology
Recent progress on advanced blast furnace mathematical models based on discrete method
ISIJ Int.
Superquadrics and angle-preserving transformations
IEEE Comput. Graph. Appl.
Geometric model for fundamental particles
Int. J. Theor. Phys.
Cited by (38)
Effects of particle angularity on the bulk-characteristics of granular assemblies under plane strain condition
2023, Computers and GeotechnicsPenetration into a granular bed in the presence of upward gas flows
2023, ParticuologyThe influence of cohesion on polyhedral shapes during mixing in a drum
2023, Chemical Engineering ScienceModelling of phenomena affecting blast furnace burden permeability using the Discrete Element Method (DEM) – A review
2023, Powder TechnologyCitation Excerpt :The repose angle is generally used as a calibration target since it is known to be affected by friction coefficients [143,172–174]. In some studies, the rolling friction coefficient is omitted when complex shapes are used to model irregular particles (e.g., the work of Schott et al. [122], Govender et al. [124] and Bester et al. [175]), so that the calibration procedure is directed towards only the sliding friction coefficient. Others included the rolling friction coefficient since they modelled particles as spheres (e.g., Liu et al. [116], Li et al. [169] and Chibwe et al. [176]), or even though non-spherical particles were used (e.g., Yu & Saxén [43], Chakrabarty et al. [145] and Chen et al. [92]).
Motion trajectory mathematical model of burden flow at the top of bell-less blast furnace based on coordinate transformation
2023, Advanced Powder TechnologyA review of recent development for the CFD-DEM investigations of non-spherical particles
2022, Powder Technology