Hot-dip Galvanizing Line Research Articles

Numerical Analysis of Fluid Flow and Heat Transfer in Molten Zinc Pot of Continuous Hot-dip Galvanizing Line.

A numerical model adopting a partially staggered grid system for the location of dependent variables has been developed to analyze the fluid flow and temperature distributions in a molten zinc pot of No. 2 CGL of POSCO Kwangyang strip mills. A control volume based finite difference procedure was employed to solve the conservation equations transformed by using the boundary-fitted-coordinate (BFC) system. The calculation results have shown that a change in the steel strip velocity has little influence on the overall flow pattern developed in the pot. The overall temperature distribution was rather uniform as predicted. However, charging cold ingots directly into the pot produced a non-uniform distribution of temperature. The local temperature fluctuations will promote the formation of intermetallic dross particles. It has been proposed that the non-uniform distribution of temperature could be reduced by selecting an appropriate channel inductor position as well as by optimizing the zinc ingot loading position.

Quality Assurance at Continuous Hot-Dip Galvanizing Lines by Neuro-Model Assisted Fuzzy-Control

The importance of improving product quality at continuous hot-dip galvanizing lines with air knives steadily grows. So the developed solutions have to be intelligent, adaptive and modular. This paper describes the revision of a conventional non-adaptive control strategy towards a modern solution using methods of computational intelligence. The already existing feedforward control is complemented by a neural process model and a neuro-fuzzy controller replaces the previously used conventional process controller. Both components are embedded carefully into the control environment so that consumption of time and material for the installation period can be held low. The neural process model is optional and is used for model-based control so that the process inherent measurement dead-time is avoided. The new control arrangement is adaptive, saves zinc, guarantees a more constant coating and relieves the operators.

Open-Loop Adaptive Feedback Control of Deposited Zinc in Hot-Dip Galvanizing at Sollac Florange

This paper describes the automation of the new hot-dip galvanizing line of SOLLAC Florange (St. Agathe - France), focusing on the main control loop: regulation of the deposited zinc. The main difficulties for implementing high-performance feedback control come from the presence of large and variable time delay (depending on the steel strip speed) and from the nonli near character of the plant model. The regulation scheme is implemented on a PC connected to the process through an industrial network. It uses a digital controller designed on the basis of an identified discrete time model. The scheme is open-loop adaptive in the sense that the sampling frequency is related to the steel strip speed and that the parameters of the controllers for various regions of operation are stored in a table. Result, obtained on the site conclude the paper

Jet stripping of molten metallic coatings

The thickness of the coating on a strip produced by modern hot-dip galvanizing lines is controlled with air jets which generate a ‘‘barrier’’ to the molten coating material as it is drawn from its bath by the emerging strip. It is shown that an improved understanding of the process and more accurate predictions may be obtained by modifying the existing theory to include the jet-induced surface shear acting in conjunction with the jet stagnation pressure gradient effect.