炼油技术与工程 ›› 2021, Vol. 51 ›› Issue (9): 40-43.

• 机械设备 • 上一篇    下一篇

酸性水单塔低压汽提塔顶空冷器腐蚀原因分析和对策

黄卫存, 钱慧琴, 于睿, 姚炳, 朱元彪   

  1. 镇海石化工程股份有限公司,浙江省宁波市 315042
  • 收稿日期:2021-05-07 发布日期:2021-11-12
  • 作者简介:黄卫存,高级工程师,大学本科,毕业于西安交通大学化学工程与工艺专业,主要从事石油化工炼油工艺设计工作,主要研究方向是硫磺回收、酸性水汽提和溶剂再生。联系电话:13566352231,E-mail:huangwc@izpec.com。

Corrosion cause analysis and countermeasures for air cooler of sour water single-tower low-pressure stripper

Huang Weicun, Qian Huiqin, Yu Rui, Yao Bing, Zhu Yuanbiao   

  1. Zhenhai Petrochemical Engineering Co., Ltd., Ningbo, Zhejiang 315042
  • Received:2021-05-07 Published:2021-11-12

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摘要： 酸性水单塔低压汽提塔顶空气冷却器(空冷器)管束泄漏情况常有发生。空冷器管束内主要介质为H2O,NH3,H2S,NH4HS等。通过分析酸性水汽提塔顶空冷器的管壁温度、液相H2S含量、液相NH3含量、H2S气相分压、NH3气相分压、管束内气体和液体流动状态,得出空冷器管束局部腐蚀主要原因是高浓度NH4HS的化学腐蚀或NH4HS结晶固体冲刷腐蚀。采取以下措施能降低空冷器管束腐蚀速率:增加注水以稀释局部NH4HS浓度;升级材质为钛、哈氏合金C276或合金 800提高耐腐蚀性;降低管束翅化比、部分空气回流、空冷器底部增加加热盘管以提高管壁温度;增加风机变频和百叶窗、管束设置10 mm/m坡度防止偏流;控制进料气速等。

关键词: 酸性水, 单塔低压汽提, 空冷器, 化学腐蚀, NH4HS结晶

Abstract: Leakage often occurs in the tube bundle of the overhead air cooler of the single-tower low-pressure stripper for sour water. The main media in the tube bundle of air cooler are H2O, NH3, H2S, NH4HS, etc. By analyzing the tube wall temperature, liquid phase H2S concentration, liquid phase NH3 concentration, gas phase H2S partial pressure, gas phase NH3 partial pressure and flow state of gas and liquid in tube bundle, it is concluded that the main cause of corrosion is chemical corrosion of high concentration NH4HS or erosion corrosion of NH4HS crystal solids. The following measures can reduce the corrosion rate of air cooler tube bundle: increase water injection to dilute local high concentration NH4HS; upgrade material to titanium, Hastelloy C276 or Incoloy 800 to improve corrosion resistance; reduce the finned ratio of the tube bundle, partial reflux of air, and add the heating coils at the bottom of air cooler to increase the temperature of the tube wall; increase the frequency conversion and louvers of fan, set 10 mm/m gradient of tube bundle to prevent bias flow; control gas speed of the feedstock, etc.    

Key words: sour water, single-tower low-pressure stripper, air cooler, chemical corrosion, NH4HS crystallization