Mathematical Modeling of Inclusions Deposition at the Upper Tundish Nozzle and the Submerged Entry Nozzle

Abstract

Nozzle clogging is still a concern for steel makers due to the high-quality requirements and productivity in the continuous casting. The present work studies the factors involved in the inclusion deposition at the nozzle wall using numerical and analytical techniques. For this, a detailed fluid dynamic analysis inside the nozzle in a coupled tundish-mold system is undertaken. The results show that the inclusions reaching the nozzle, only 30% get deposited along its walls mainly at the upper tundish nozzle (UTN) and at the submerged entry nozzle (SEN) ports. These areas of higher deposition are identified close to a low static pressure and a high turbulent kinetic energy dissipation zones. The high-energy dissipation induces a fluctuant velocity increment; consequently, the mean flow velocity increases forcing a reduction of the static pressure in order to preserve the mechanical energy balance. This mechanical energy imbalance is identified as mechanical energy dissipation being recognized by an increment in the vorticity and quantified by an additional term into Bernoulli equation. This complex phenomenon induces zones of high turbulent flow from which the inclusions tend to move toward lower turbulence regions, explaining why the inclusions get deposited in these two typical zones promoting the deleterious clogging phenomenon.

A Study on the Nonmetallic Inclusion Motions in a Swirling Flow Submerged Entry Nozzle in a New Cylindrical Tundish Design

“…In order to understand the deposition location and mechanism, computational fluid dynamics (CFD) studies have been carried out to investigate the inclusion transport in turbulent steel flows and its deposition on the SEN walls. [9][10][11][12][13][14][15][16][17] Deposition rates of inclusions on the SEN wall were predicted by using an Eulerian deposition model, which considered the transport of inclusions in the turbulent flow boundary layer as well as the turbophoresis effect. [16,17] Finally, inclusions move into the mold accompanying steel flows, where the solidification of molten steel happens.…”

Review on Modeling and Simulation of Continuous Casting

“…In addition to lowering productivity, clogging is detrimental to steel quality due to the releasing of clogs, which generates both large inclusions and unstable flow in the mold, leading to excessive surface level fluctuations . Nozzle clogging has been investigated using models to simulate the inclusion attachment process by a few researchers . In these models, particle transport and attachment can be modeled using a fluid flow model for the velocity and pressure fields, combined with a Lagrangian particle tracking method, such as the Discrete Particle Method (DPM) for the inclusions.…”

“…[90] Nozzle clogging has been investigated using models to simulate the inclusion attachment process by a few researchers. [64,[90][91][92] In these models, particle transport and attachment can be modeled using a fluid flow model for the velocity and pressure fields, combined with a Lagrangian particle tracking method, such as the Discrete Particle Method (DPM) [93][94][95][96] for the inclusions. Argon gas can disrupt this clogging process, by changing the flow pattern.…”

Removal Mechanism of Microscale Non-Metallic Inclusions in a Tundish with Multi-Hole-Double-Baffles

“…Owing to the increasingly stringent quality requirements, many studies have investigated the equipment, process, and theoretical principles of continuous casting, particularly for the tundish, which is the final metallurgical element reactor [1][2][3][4][5][6]. To improve the removal of inclusions by the tundish, many flow control devices, such as the turbulence inhibitor, weir-dam, baffle with holes, and filter and gas-curtain device, have been developed to optimize the flow field, increase the residence time, and promote inclusions' removal [7][8][9][10][11][12][13][14][15][16][17][18].…”