Modelling of valve induced water hammer phenomena in a district heating system

• 1D thermal–hydraulic computer code RELAP5 was used to model transients in a district heating system.
• The developed model of the system was used to evaluate possible threats to pipeline integrity.
• A potential threat is possible only assuming a different system configuration and delayed valve closure.

Water hammer is one of the most dangerous phenomena in liquid or liquid/gas systems, because it can cause failure of the system integrity. A water hammer in a district heating system is investigated in this article. The reasons of the water hammer phenomenon are investigated quite well in the scientific literature. However, the conditions when the water hammer may occur depend on the specific system and the thermal–hydraulic specifics of the system. In this paper an accident scenario of blackout in a pump station is investigated and the analysis of fast check valve closure due to a pump station blackout is presented in the paper. A computer code RELAP5 was employed to perform accident analysis. The analysis showed that under some hypothetical conditions, pressure peak could exceed the value used during the hydraulic tests of the pipelines.