Thermodynamic and physical properties as basis for digitalization of glycol processes

For a better understanding, qualification, and design of these installations, new thermodynamic modeling is necessary. Therefore, this work aims both experimental and modelling work, to develop online models for monitoring and predictive maintenance of these operations.

Subsea processing facilities are increasing, due to their several advantages over onshore processing, mainly related to the limitations and risks inherent in multiphase pipelines and the inhibition of contamination of the pipelines with water, which can result in the formation of gas hydrates or, when combined with other natural gas components, leads to corrosion. 

Among these processes, the dehydration of natural gas is of specific interest to this work. Glycol absorption is by far the most widely used method for industrial applications in this case, as it acts both as a hydrate inhibitor in gas transport lines as a dehydrating agent for gas processing applications. In addition, its lower viscosity helps in direct injection applications, especially at the low temperatures present in underwater units.

To carry out the dimensioning of equipment and the selection of absorbents for process projects and feasibility studies of such installations, however, it is necessary to use precise thermodynamic models, which require a wide range of reliable equilibrium data. Unfortunately, very few glycol-related datasets are found in the open literature today.

This work, therefore, focuses on the development of online models for monitoring and predictive maintenance of glycol processes for unmanned operations. This will involve obtaining experimental data from glycol systems over a wide range of temperature and pressure. Measurements will be primarily to understand phase equilibrium, but other properties may also be needed (glycol density and heat capacities). Furthermore, new parameters and improve numerical robustness of the CPA-EoS fit into the main objective.