A study on temperature–stress model of pre-cooling for re-condenser in LNG receiving station

Pre-cooling in a re-condenser is one of the key tasks for the smooth operation in a liquefied natural gas receiving station. It should be conducted economically and efficiently to ensure operation safety so that the re-condenser material damage caused by the thermal stress can be avoided. In this paper, a pre-cooling temperature model based on the computational fluid dynamics technology has been established to complete the large-grid calculation in the re-condenser. Combined with the component transport equation and volume of fluid multi-phase flow model, a theoretical system has been built which can be applied to both the gas phase pre-cooling model and the liquid phase pre-cooling model. The fast and stable calculation of the multi-component multiphase and large-scale has been realized through controlling the grid optimization, dynamic relaxation factor, and phase change model selection. To realize the coupling between the temperature model and the stress model and analyze the thermal stress caused by the temperature change in the pre-cooling real time, a pre-cooling stress model has been constructed and a temperature difference algorithm has been proposed. After analyzing the overall and local model of the re-condenser, the thermal deformation and thermal stress during the pre-cooling of the re-condenser can be comprehensively analyzed, and the detailed analysis of the stress and fatigue life at the peak stress region (e.g., the nozzle) can be achieved. The prediction accuracy of the pre-cooling temperature–stress model has been verified by the on-site measured data. They have great popularizing and applying values. The two models can provide scientific support in pre-cooling scheme design, optimization, pre-cooling flow, and structural safety, and when applied to engineering, they can lead to significant economic and safety benefits.