Emissivity and oxidation evolution in reheating furnace environments

再加热炉环境中的发射率和氧化演化

• 批准号: 2610326
• 金额: --
• 依托单位: Swansea University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2610326
• 关键词: Emissivity; oxidation; evolution; reheating; furnace

Reheating furnaces are an essential part of Tata Steel Europe's hot mills. Reheating furnaces are heated by gas burners and aim to heat the steel slabs to their rolling temperature with a known temperature profile through the thickness. Reheating furnaces rely predominantly on heat being radiatively transferred to the slabs. Since steel is prone to oxidation, the slabs grow an oxide layer on their surface. This has two major effects for the heat transfer from the furnace to the slab: It changes the emissivity of the surface, and therefore the power the slab absorbs from the furnace. It introduces an insulating layer on the surface of the slab, which slows thermal diffusion into the slab. The oxide layer thickness can be approximately calculated for simple steels, however the evolution of emissivity with time and temperature as well as its dependency on the oxide thickness or topology of the oxide surface is unknown. The emissivity of oxide scales is known to be affected by a number of parameters, including the composition of the atmosphere, steel grade, temperature, steel surface condition and time. Some of these parameters are within our control, for example the composition of the atmosphere in the reheating furnace, the temperature cycle or the steel composition. In this project, we would like to understand how temperature cycle and eventually furnace atmosphere affects the surface condition of the oxide scale, and therefore the emissivity. The first industrial aim is to be able to introduce accurate emissivity values in the furnace model as a function of time and temperature, the second aim is to extrapolate this prediction to different steel compositions. An additional aim, if time permits, is to understand how to control the emissivity to maximise it and improve furnace efficiency. The objectives of the project include: Develop and validate an experimental setup that can measure the emissivity of oxide scales as a function of temperature and time. Measure emissivity as a function of temperature and evolution in time for HSLA and low carbon grades heated in an environment representative of a reheating furnace atmosphere. Relate emissivity changes to changes in the oxide layer, e.g. morphological, structural, or compositional changes. Formulate the relation emissivity, time, temperature, and steel composition to be used in the industrial model. Suggest, if time permits, the optimised furnace parameters, or slab surface modifications to achieve maximum emissivity on the slabs.

加热炉是塔塔钢铁欧洲热轧厂的重要组成部分。加热炉是由气体燃烧器加热的，目的是将钢坯加热到其轧制温度，并在整个厚度上具有已知的温度分布。加热炉主要依靠热量辐射传递到板坯上。由于钢很容易氧化，板坯表面会生长一层氧化层。这对从炉子到板坯的热传递有两个主要影响：它改变了表面的发射率，从而改变了板坯从炉子中吸收的能量。它在板坯表面引入了一层绝缘层，减缓了热扩散到板坯中的速度。对于简单的钢，氧化层厚度可以近似计算，但发射率随时间和温度的变化及其对氧化层厚度或氧化物表面拓扑的依赖关系尚不清楚。众所周知，氧化膜的发射率受许多参数的影响，包括大气的组成、钢种、温度、钢的表面状况和时间。其中一些参数在我们的控制之下，例如加热炉内的气氛成分、温度循环或钢的成分。在这个项目中，我们想要了解温度循环和最终的炉膛气氛如何影响氧化膜的表面状况，从而影响发射率。第一个工业目标是能够在炉子模型中引入作为时间和温度函数的准确发射率值，第二个目标是将这一预测外推到不同的钢成分。如果时间允许，另一个目标是了解如何控制发射率，以使其最大化并提高炉子效率。该项目的目标包括：开发和验证一种实验装置，该装置可以测量氧化膜的发射率随温度和时间的变化。测量在代表加热炉气氛的环境中加热的HSLA和低碳等级的发射率随温度和时间演变的函数。将发射率的变化与氧化层的变化相关联，例如，形态、结构或成分的变化。制定工业模型中使用的发射率、时间、温度和钢材成分之间的关系。如果时间允许，建议优化炉子参数，或对板坯表面进行修改，以实现板坯的最大发射率。