加氢空冷系统硫氢化铵结晶规律的数值模拟

Numerical Simulation of Ammonium Hydrosulphides Crystallization Rules in Hydrogenation Air-Cooling System

通过对加氢空冷系统NH4HS结晶沉积机理的分析,结合物性仿真计算得到典型工况下NH4HS结晶反应的起始温度。采用HTRI软件获得空冷器管束不同位置的温度分布情况,确定开始发生NH4HS结晶反应的具体位置。通过数值模拟获得流动场、温度场和浓度场作用下的NH4HS结晶沉积规律。研究结果表明:典型工况下加氢空冷系统中发生NH4HS结晶反应的起始位置在第5/6排管束距入口5.9 m处;结晶反应速率最大值位于气相中且靠近气液界面,生成的铵盐颗粒在气相空间靠近上壁面处扩散速率最快,且易沉积于管束顶端;仿真得到最大铵盐沉积量的区域为距出口3.32 m处,与现场检测数据相吻合。研究结果可为后续铵盐沉积腐蚀的定量分析提供依据。

Based on the analysis of ammonium hydrosulfide crystal aggradation mechanism in hydrogenation air-cooling system, it can figure out the starting temperature of ammonium hydrosulfide crystallizing reaction under typical working condition by simulation calculation of the matter properties. Using HTRI software can obtain the temperature distribution situation of different positions in air cooler tube bundle, so that it can ascertain the specific starting position of ammonium hydrosulfide crystallizing reaction in the tube bundle. On the basis of numerical simulation, it can get the deposition rules of ammonium hydrosulfide crystal under the effects of flow field, temperature field and molarity field. The results show that the starting position of ammonium hydrosulfide crystallizing reaction in hydrogenation air-cooling system under typical working condition is 5.9 m away from the inlet in the 5/6 tube bundle. The maximum crystallizing reaction rate is in gaseous phase and where is near the gas-liquid interface. The diffusion rate of generated ammonium salt particles is fastest in the gaseous phase space where is near the upper tube wall, and the particles in there are easy to deposit at the top of the tube. The area with the maximum amount of ammonium hydrosulfide crystal deposition is 3.32 m away from the outlet, which is consistent with the actual data obtained by practical measurements. The results of this study can provide the basis for quantitative analysis of subsequent ammonium salt deposition corrosion, which is of great available value.