回转窑筒体裂纹红外无损在线检测研究

Research on Infrared Nondestructive Online Detection of Cracks in Rotary Kiln Shell

回转窑广泛应用于水泥、冶金、建材、化工等流程化工业领域,回转窑筒体承担着物料的煅烧、分解和物料输送等工艺过程。由于回转窑是高温设备,窑筒体突发性故障及其不稳定运行严重威胁着企业安全生产和产品质量。回转窑生产工况复杂且受多种复杂情况影响,导致回转窑筒体裂纹频繁发生,从裂纹产生的位置、走向及裂纹不可预见的扩展速度看,回转窑筒体裂纹成因复杂,存在较大的离散性,给企业安全生产和稳定运行带来很大的隐患。以水泥工业用回转窑5000 t/d生产线(4.8 m×74 m回转窑)作为研究对象,对比分析了传统无损检测方法的优点与局限性,依据现场回转窑筒体容易出现缺陷裂纹区域的实物尺寸为例,建立三维导热模型,并对样本施加不同的温度载荷,利用ANSYS数值模拟仿真结果,分析探究了不同裂纹尺寸、不同热载荷温度在材料特性的条件下,对回转窑筒体表面温度梯度变化影响,获得了裂纹区与无裂纹区的表面温差变化规律;在此基础上,为回转窑筒体裂纹红外无损检测提供了参考理论依据。

Rotary kiln is widely used in cement,metallurgy,building materials,chemical industry and other process industries.Since the rotary kiln is a high-temperature equipment,the sudden failure of the kiln cylinder and its unstable operation seriously threaten the safety production and product quality of the enterprise.The production conditions of the rotary kiln are complex and affected by various complicated situations,resulting in frequent occurrence of cracks in the rotary kiln cylinder.From the position,direction and unpredictable propagation speed of the cracks,the causes of the defects of the rotary kiln cylinder are complex,and there are large defects in the rotary kiln.The discreteness of the system brings great hidden dangers to the safe production and stable operation of the enterprise.This paper takes the rotary kiln 5000t/d production line(4.8m×74m rotary kiln)for cement industry as the research object,and compares and analyzes the advantages and limitations of traditional nondestructive testing methods.As an example,a three-dimensional thermal conductivity model was established,and different temperature loads were applied to the samples.Using the ANSYS numerical simulation results,it was analyzed and explored how different defect sizes,different heat load temperatures and material characteristics affected the rotary kiln cylinder.Influenced by the change of surface temperature gradient,the variation law of surface temperature difference between the cracked area and the non-cracked area was obtained;on this basis,a reference theoretical basis was provided for the infrared nondestructive detection of cracks in the rotary kiln cylinder.