Innovative Integrated Process Scheme for Native CO2 Recovery

While considering CO2 emission from a gas plant, native CO2 significantly contributes to the total amount. Capturing this native CO2 can reduce a lot the green house gases emission and captured CO2 can be valorized for Enhanced Oil Recovery. Due to this, Oil and Gas operators are more and more interested in improving native CO2 recovery technologies. Usually when natural gas contains both CO2 and H2S, they are removed together and sent to Sulfur Recovery Unit resulting in a tail gas containing mainly Nitrogen and CO2. CO2 can then be separated by use of solvent (using MEA e.g.). TOTAL and Air Liquide have developed and patented an innovative process scheme recovering native CO2 and reducing the operating and investment costs. Claus unit fed with pure oxygen instead of air leads to a tail gas stream, containing mainly CO2 and H2. Then, CO2 purification unit allows recovering a CO2 rich stream with purity even up to 99.9%. This purification unit can be either membrane, cryogenic or adsorption technologies, or a combination of them. This paper also discusses about the integration of Oxygen-based Claus technology (OxyClaus), tail gas treatment unit (TGTU) and CO2 purification. The scheme has been studied in detail for specific application to optimize the overall integration. It has been also compared to conventional CO2 capture scheme to highlight its benefits leading to significantly lower CO2 recovery cost. This scheme contributes in many aspects to the current technical knowledge which may include low-cost CO2 capture, use of pure oxygen in the Claus, CO2 purification for EOR etc. Other benefits also include the size reduction of the Claus/TGTU, production of nitrogen stream to be valorized and separated H2-rich stream from CO2 purification unit. This paper will comprise the overall scheme description and discuss some results for the specific case study.