加氢裂化空冷器管束多相流冲刷腐蚀数值模拟

Numerical Simulation of Multiphase Erosion-corrosion of Tubes Bundles of Hydrocracking Air Cooler

基于某加氢裂化空冷器管束的冲刷腐蚀实际状况分析,建立了数值模拟模型。采用mixture模型和标准k-ε模型描述多相湍流流动过程,以此对空冷器的管箱、管束进行全流场数值模拟,获得湍动能分布状况;进而对空冷器腐蚀状况进行研究,获得不同位置处的冲刷腐蚀和电化学腐蚀速率。结果表明,最大冲刷腐蚀速率达到4.76 mm/a,且腐蚀损伤集中在空冷器管束进口端,模拟结果与空冷器管束实际腐蚀状况一致。模拟结果表明,与电化学腐蚀相比,冲刷腐蚀是导致空冷器管束腐蚀损坏的主要原因。在此基础上,提出对空冷器结构进行改进的技术方案;模拟计算表明,结构改进后的空冷器管束的冲刷腐蚀速率大大降低,显著提高了空冷器运行的安全与稳定性。

Air cooler is the key equipment in the process of hydrocracking.The corrosion of air cooler becomes a prominent problem in the safe and stable operation of equipment.In this paper,a numerical simulation model is established based on the analysis of the erosion corrosion of the air cooler tubes in a hydrocracking unit.The mixture model and the standard k-εmodel of CFD simulation software is used to simulate the whole flow field of the tube box and tube bundle of the air cooler.The corrosion position of the air cooler is predicted by the turbulent kinetic energy distribution.The corrosion amount of erosion corrosion and electrochemical corrosion are predicted as well.According to the simulation,the maximum erosion amount is 4.76 mm/a,and it is concentrated at the inlet of the tube bundle of air cooler.The simulation results are consistent with the actual corrosion of the air cooler.Comparing with electrochemical corrosion,erosion corrosion is the main cause of corrosion of air cooler.The amount of erosion and corrosion of the tube bundle of air cooler has been greatly reduced after the retrofit of the air cooler structure,therewith,the safety and stability of the air cooler have been greatly improved.