Construction of a computational model for the process of cooling down a cryogenic storage facility for liquefied natural gas

Abstract

As part of the preparation of the cryogenic storage facility for operation, the following processes are performed during commissioning: inerting – displacing air from the tank volume in order to exclude the possibility of forming an explosive mixture; substitution – replacing neutral gas (nitrogen) with methane; chilling – cooling the storage tank structure to a temperature of 143 K. Chilling allows to reduce the amount of regasified gas during loading and storage, eliminate the occurrence of low-temperature stresses in the structural elements, and reduce the likelihood of emergency situations during operation. This article presents a comparative analytical study of the process of two-phase and convective cooling of a cryogenic storage facility for liquefied natural gas. The Kantorovich–Bubnov–Galerkin method is used to model non-stationary heat exchange in the storage facility's insulating structure. This method allows obtaining approximate analytical solutions describing temperature fields and cooling dynamics. As part of the study, dependencies of the change in temperature pressure on the inner wall of the tank during cooling with methane and air over time are obtained, and graphs of isotherms in the gas space of the tank during convective cooling with air were constructed.