Modelling the blowdown of pressure vessels

The rapid depressurisation of pressure vessels containing hazardous substances in chemical plants, known as blowdown, is a critical process for ensuring plant safety. Blowdown significantly reduces the inventory as well as duration and rate of potential leaks, thereby mitigating the risks of escalation, fire and explosion. In the present paper we propose a rigorous model for simulating the blowdown process, taking both real gas behaviour, heat transport from the surroundings and the vessel wall as well as non-equilibrium between vapour and liquid phase into account. The model is compared against well-known experiments performed at Imperial College and Spadeadam test facility, which has been used extensively for the validation and benchmark of numerous academic and commercial codes with similar capabilities as the present model. The experimental validation of the developed model show good predictive capability and that the model captures both measured pressure, phase temperatures as well as predicted wall temperatures with adequate accuracy, both for single phase and condensing conditions.