填料复合型蒸发空冷器管束腐蚀分析及预防

Corrosion failure analysis and anticorrosion measures for a tube bundle in a packing-type evaporative air cooler

针对填料复合型表面蒸发式空冷器在运行过程中出现管束泄漏问题。本文利用X射线衍射(XRD)、X射线荧光光谱分析(XRF)、扫描电镜及能谱分析对管束及腐蚀垢物进行分析,并采用金相显微镜对换热管泄漏部位及完好部位进行微观组织分析。结果表明,换热管束的腐蚀类型主要有均匀腐蚀、小孔腐蚀、缝隙腐蚀、温差电池腐蚀,腐蚀垢物中ZnO约为41.5%、Fe_2O_3为27.8%、C为13.8%(烧碳处理)、SiO_2为10.5%。换热管束的底面腐蚀比换热管束的顶面腐蚀严重,通过添加缓蚀剂及保证喷淋水密度可减缓换热管管束腐蚀。

A tube bundle in a packing-type surface evaporative air-cooler experiences leaks during operation. In this paper, the microstructure and corrosion substances in the bundle were analyzed and tested by X-ray diffraction （XRD） , X-ray fluorescence spectrometry （XRF） , scanning electron microscopy （SEM） and an energy-spectrum analysis. The microstructures of the leaking portion and the intact portion were analyzed by metallographic microsco- py. The experimental results show that the corrosion modes of the bundle include general corrosion, pitting corro- sion, crevice corrosion and temperature-difference battery corrosion. The corrosion substance is composed of 41.5% ZnO, 27.8% Fe2O3, 13.8% C, and 10.5% SiO2. The corrosion on the bottom of the bundle is more severe than that on the top of the bundle. The corrosion can be minimized by adding corrosion inhibitors and providing adequate spray water.