Numerical simulation of a 374 tons/h water-tube steam boiler following a feedwater line break

• We simulate the behavior of a steam boiler during feed-water line break accident.
• To perform accident analysis of the steam boiler, Relap5/Mod3.2 system code is used.
• A Relap5 model of the boiler is developed and qualified at the steady state level.
• A good agreement between Relap5 results and available experimental data.
• The Relap5 model predicts well the main transient features of the boiler.

To ensure the operational safety of an industrial water-tube steam boiler it is very important to assess various accident scenarios in real plant working conditions. One of the most challenging scenarios is the loss of feedwater to the steam boiler. In this paper, a simulation of the behavior of an industrial water-tube radiant steam boiler during feedwater line break accident is discussed. The simulation is carried out using the RELAP5 system code. The steam boiler is installed in an Algerian natural gas liquefaction complex. The simulation shows the capabilities of RELAP5 system code in predicting the behavior of the steam boiler at both steady state and transient working conditions. From another side, the behavior of the steam boiler following the accident shows how the control system can successfully mitigate the effects and consequences of such accident and how the evaporator tubes can undergo a severe damage due to an uncontrolled increase of the wall temperature in case of failure of this system.