Design and engineering implementation of blowdown system for cryogenic CO2- NG pilot facility

As easy gas resources around the world are depleting; high Carbon Dioxide (CO2) gas fields are thrust into the spotlight to become new candidates for field development. However, the presence of oftentimes sizable Carbon Dioxide contents in the gas reservoir (can be up to 80 volumetric) introduced a huge technical and economic challenges towards the field exploitation. 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 solids formation, hence potential blockage of process equipment and venting line. Therefore, this paper will focus on the design of the pressure relieving system of such a facilities. It would also touched on the implementation of the pressure relieving system during the operation of the pilot tests and as well as the tests designed specially to test the pressure relieving system. Finally the paper would give a few proposals on improvements to be made to such system. It is also the ultimate aim of the authors and the team to introduce a new philosophy for Cryogenic CO2 Blowdown system to the process industry. Copyright 2019, Society of Petroleum Engineers.