(54bm) State of the Art Development of Emergency Depressurization System for High CO2 Cryogenic System

Over the last few years, several studies have been conducted on cryogenic technologies such as cryogenic distillation and supersonic nozzle in CO2 separation for fields containing more than 40% of CO2. Based on the studies, these new cryogenic technologies have shown to have high potential in separating CO2 from natural gas offshore to be utilized under carbon, capture, storage and utilization (CCUS) project.

The new cryogenic technologies are currently being tested for the proof of concept. Hence, a pilot plant, which is a scaled down version of the technology was developed. One of the major challenges faced during the pilot plant testing is the emergency depressurization philosophy as the process involves CO2 solids handling which is uncommon to the industry standard. Depressurization of high CO2 fluid at cryogenic temperature would lead to possibility of CO2 solid formation, hence potential blockage of process equipment and venting/flaring line.

Due to the thermodynamic properties of CO2, there is a risk associated with CO2 solid formation that can lead to blockages in the system. This paper focuses on the experimental approach to understand the phenomena of CO2 solid formation under expansion, which includes the PVT measurement conducted for mixtures containing CO2 and hydrocarbons under low temperature to predict the phase envelope, interfacial tension measurement (IFT) and nucleation test to predict the solid CO2 formation delay as well as the agglomeration of the solid CO2 in the system. These experimental studies have given a dynamic insight in understanding the scientific phenomena further which can be used to optimize the design of the blowdown system. The experimental data is used to validate the equation of state in modelling the blowdown simulation for CO2 solid prediction. The optimized design of blowdown system will be used for the pilot plant testing of the CO2 separation technology and its future offshore installations.