This work presents a Modelica model for an ammonia stripper that is used to process waste (digestate) from a biogas production unit. The model includes the chemical balance equations between species in the liquid and gas, and includes the exchanges between both phases and the energy consumption of the unit. Results show the expected behaviour with an increasing pH with time, with further validation and calibration being necessary once experimental results are available. This is a novel use of Modelica designed to expand the library of processes that are simulated using this approach.

Offshore oil facilities are complex systems that involve elaborate physics combined with stochastic aspects related, for instance, to failure risk or price variation. Although there exist many dedicated software tools to simulate flows typically encountered in oil exploitations, there is still no tool that combines physical (mostly engineering fluid mechanics) and risk simulation. Such a tool could be useful to engineers or decision makers for specification, design and study of offshore oil facilities. We present a first step towards the creation of such a tool. Our current simulator is based on new Modelica components to simulate fluid flows and on stochastic simulation at a higher level, for modeling risk and costs. Modelica components implement physical models for single and two-phase flows in some typical devices of an offshore field. The risk simulation uses Markov chains and statistical indicators to assess performance and resilience of the system over several months or years of operation.

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