Development of a bench-scale liquid metal wiping pilot system for understanding and optimizing the jet wiping process during hot dip galvanizing

开发小型液态金属擦拭试点系统，用于了解和优化热浸镀锌过程中的喷射擦拭过程

• 批准号: 565310-2021
• 负责人: Chattopadhyay, Kinnor
• 金额: $ 1.82万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Alliance Grants
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=722200
• 关键词: Development; bench; scale; liquid; metal

In the case of hot-dip galvanizing, a continuously-moving steel strip is coated with a thin layer of zinc in orderto resist to oxidization. The protective metal is applied in its liquid state, by dipping the substrate into a bath ofcoating. However, at common strip speeds, the liquid layer dragged by the moving web is far too thick anduneven for the applications considered. The final coating thickness is therefore controlled by an air knife,which impinges a two-dimensional high-speed gas jet on the liquid layer. The forces imposed in the liquid bythe air knife jet results in the formation of a runback flow down to the bath, leaving a more uniform andconstant coating thickness dowsntream on the substrate. Nevertheless, operational constraints and processparameter variation can still result in significant coating non-uniformity and excess zinc consumption. Thisresearch program will focus on developing a bench scale galvanizing pilot where a low melting point liquidmetal will be used as an analogue to zinc and a rotating belt arrangement will be combined with an air knife tovisualize the jet wiping process in more detail. State of the art imaging techniques developed at the applicant'slaboratory will be used to visualize the wiping process, coating waviness and solution strategies will beproposed for optimizing the wiping system in terms of process parameters and air knife design. With manyexisting problems at the hot dip galvanizing lines it is difficult to meet the market demands. The results of thisproject are expected to help galvanized strip producers like AM Dofasco to determine, and control theoptimum coating properties that will allow them obtaining the highest productivity and simultaneously achievehigh quality strips with desired product quality. Proper understanding of the jet wiping process and itsinfluence on galvanized product quality has profound impacts on the commercial aspects of hot dipgalvanizing. Based on the current interests in this process optimization, and enhanced productivity (expressedby AM Dofasco hot dip galvanizing lines), an economic impact of $6 million /year is expected from the resultsof this research, which translates to $30 million within five years after completion of this project

在热镀锌的情况下，连续移动的钢带被涂上一层薄锌以抵抗氧化。通过将基材浸入镀膜液中，使保护金属处于液态状态。然而，在普通带材速度下，移动网所拖动的液体层太厚且不均匀。因此，最终涂层厚度由空气刀控制，空气刀撞击液体层上的二维高速气体射流。气刀射流对液体施加的力导致回流到镀液中，在基材下游留下更均匀和恒定的涂层厚度。然而，操作限制和工艺参数的变化仍然会导致显著的涂层不均匀性和过量的锌消耗。该研究计划将重点开发一个实验规模的镀锌试点，其中低熔点液态金属将用作锌的模拟物，旋转带安排将与气刀相结合，以更详细地可视化喷射擦拭过程。申请人实验室开发的最先进的成像技术将用于可视化擦拭过程，涂层波浪度和解决方案策略将被提出，以优化擦拭系统的工艺参数和气刀设计。热浸镀锌生产线存在诸多问题，难以满足市场需求。该项目的结果有望帮助像AM Dofasco这样的镀锌带生产商确定和控制最佳涂层性能，从而使他们能够获得最高的生产率，同时实现高质量的带材和所需的产品质量。正确理解喷射擦拭工艺及其对镀锌产品质量的影响对热镀锌的商业方面有着深远的影响。根据目前对这一工艺优化的兴趣，以及提高生产率（通过AM Dofasco热镀锌线表示），这项研究的结果预计将产生600万美元/年的经济影响，在该项目完成后的五年内，这将转化为3000万美元