Impingement Density Analysis on Heat Transfer and the Appearance of Edge Cracks in Conventional Slab Using Hydraulic Nozzles

Alfonso Ruiz-Pineda,Alicia Aguilar-Corona,Gildardo Solorio-Díaz,Romeo Omar Preciado-Martínez,José Ángel Ramos-Banderas,Constantin Alberto Hernández-Bocanegra

doi:10.3390/met12010108

Abstract

In this work, the fluid dynamics and heat transfer of two hydraulic nozzles used in the secondary cooling of the conventional slab continuous casting machine were analyzed. Impingement density maps, the jet opening angle and heat flux associated with different operating conditions (impingement distance, pressure) were experimentally determined. The opening angle and impingement density footprint were found to vary considerably in shape and magnitude with varying operating pressure and distances. Finally, it was found that when short operating distances are used, a greater heat extraction gradient occurs in the major axis of the impingement footprint, which promotes edge-cracks in the slab in plant.

Highlights

Hydraulic and pneumatic nozzle cooling is widely used in the secondary cooling of continuous casting as it provides a good balance in terms of its ability to remove high heat fluxes, efficiently uses liquid and obtains good uniformity in the temperature of the solidified product
Some studies related to the estimation of the heat transfer coefficient and heat flux have been carried out, using experimental and numerical models [14,15], in order to improve the efficiency in the cooling of metal parts [7,13,16]
The main aim of this research is to analyze the impingement maps produced by two hydraulic nozzles and to quantify the heat extraction in the stainless-steel plate varying the operating conditions

Summary

Introduction

Hydraulic and pneumatic nozzle cooling is widely used in the secondary cooling of continuous casting as it provides a good balance in terms of its ability to remove high heat fluxes, efficiently uses liquid and obtains good uniformity in the temperature of the solidified product. Ito et al [19] investigated the effect of hydraulic pressure and the flow of water from sprays produced by hydraulic nozzle on the cooling intensity through laboratory experiments and plant tests They found that by increasing the water pressure, the average heat transfer coefficient reaches 2.8 times higher when using the same impingement density (16 m3 ·h−1 ·m−2 ), and with this, the casting speed is increased by 30% without internal or superficial cracks. Many researchers agree that impingement density is the parameter that has the most influence on the cooling stage [4,20,21,22,23,24] and should be taken into consideration when designing the secondary cooling nozzle arrangement For this reason, the main aim of this research is to analyze the impingement maps produced by two hydraulic nozzles and to quantify the heat extraction in the stainless-steel plate varying the operating conditions. We aim to elucidate the causes of edge-cracks in the slabs, according to the current operating conditions in the plant

Objectives

Methods

Results