Analysis of the Possibility of Fluid Freezing in the Discharge Pipes of Pressure Vessels

Discharge pipes play an essential role in some pressure vessels, but their safety hazards are often underestimated in the industrial operations. Particularly in low-temperature environments, the medium inside the discharge pipes may expand due to freezing, and when this frost heave stress exceeds the limit load of the pipe material, strength failure occurs, leading to serious safety issues. To prevent the freezing, thermal insulation layers and heating systems are used to maintain the temperature of the medium inside the pipes. To acquire an in-depth insight of this phenomenon, this study employs computational fluid dynamics (CFD) simulation calculations to explore the impact of insulation layer damage and heating medium temperature on the temperature field distribution and freezing conditions inside the discharge pipes. The study found that the damage level of the thermal insulation layer and heating medium temperature have significant effects on the temperature field distribution and freezing conditions of the discharge pipes. Specifically, the thermal insulation layer damage would lead to increase heat loss, thereby reducing the temperature of the medium inside the discharge pipes and increasing the risk of freezing. On the other hand， insufficient heating temperature fails to provide enough heat to prevent medium freezing. Further comparison of these two factors reveals that heating medium temperature has a more significant impact on the freezing conditions of the medium inside the discharge pipes. This means that under extreme low temperature conditions, even if the thermal insulation layer is intact, the medium inside the pipes may still freeze when the heating temperature is insufficient. Therefore, real-time monitoring of the heating status of the discharge pipes is particularly important during operation.