加氢空冷多相流热耦合数值分析

加氢空冷管束多发铵盐流动腐蚀而泄漏。铵盐腐蚀风险又取决于设备中的气相分压、介质流速和温度等特征参量。为有效预防铵盐腐蚀,探明介质流速及温度等参量间的相关特性与作用机制十分必要。鉴于此,采用对流传热耦合与RANS模型、根据设备在役工况,对空冷设备进口管箱、管束中的多相流介质流场展开流热耦合数值模拟分析,讨论在役空冷设备进口管箱和管束中的流态和温度场变化。流场状态因射流卷吸机制将形成横向脉动,脉动随着时间推移趋于稳定,而湍流动能也会因为介质脉动范围的扩展而耗散、降低。同时,多相流介质全场的温度最低值也将随时间推移而升高并趋于稳定,各管温度场沿介质流出方向会出现高低波动。考察各管流速及温度值还得到了流速同温度间的相关系数,进口管箱中两排管束的流速和温度均存在较高的相关度。之所以温度随时间推移会趋于稳定,而流速、温度二者存在较高相关度可从流场能量方程予以阐释。基于此,工程实际中可参照不同位置管束红外测温结果、估算流速,进而科学预测、有效防范空冷管束铵盐流动腐蚀。

Numerical simulation analysis on multiphase flow of hydrogenation air cooler based on thermal-flow coupling method

Hydrogenation air cooler tube bundle often leaks due to the flow-induced corrosion of ammonium salt.The corrosion risk of ammonium salt depends on the characteristic parameters such as gas partial pressure,medium velocity and temperature in the equipment.In order to effectively prevent corrosion of ammonium salt,it is necessary to make certain the properties and mechanism of action among parameters such as velocity and temperature of medium.In view of this,convection heat transfer coupling and RANS model were adopted to carry out numerical simulation analysis on the flow field of multiphase flow medium in the inlet channel box and tube bundle of air cooling equipment according to the working conditions of the equipment,and the changes of flow state and temperature field in the inlet channel box and tube bundle of the air cooling equipment were discussed.The flow field state will form transverse pulsation due to the jet entrapment mechanism.The pulsation tends to be stable over time,while the turbulent kinetic energy will be dissipated and reduced due to the expansion of the pulsation range of the medium.At the same time,the min.temperature value of the whole field of the multiphase flow media will increase and tend to be stable with the elapse of time,and the temperature field of each tube will fluctuate along the direction of the medium outflow.The correlation coefficient between the flow velocity and temperature of each tube was also obtained,and there was a high correlation between the velocity and temperature of the two rows of tube bundles in the inlet channel box.The reason why temperature tends to be stable over time is that there is a high correlation between flow velocity and temperature,which can be explained from the energy equation of flow field.Based on this,in practice,the flow speed can be estimated by referring to the infrared temperature measurement results of the tube bundles at different locations,so as to scientifically predict and effectively prevent the corrosion of the air-cooled tube bundles induced by ammonium salt flow.