Innovative CO₂ Capture Technique for Natural Gas Operations 

Introduction: A breakthrough process that combines a new category of membranes with amine solvent technologies offers an energy-efficient and economical alternative for CO₂ capture at gas plants. This hybrid approach presents a cost-effective and energy-saving solution compared to traditional absorption-based CO₂ capture methods, reducing greenhouse gas emissions and enhancing CO₂ capture capabilities.

Body: During the acid gas removal stage, CO₂ is removed along with H₂S and sent to the Claus unit, where H₂S is converted into elemental sulfur. High CO₂ content in the acid gas feed to Claus unit leads to operational challenges in the Claus Unit. It may also cause a significant drop in the reaction furnace temperature, reducing the Claus unit’s effectiveness in processing harmful compounds such as ammonia, BTX, and heavy hydrocarbons.

Currently, some gas plants already implement a method that partially removes CO₂ from the Claus unit's acid gas feed using H₂S-selective amines. This process produces two streams: a stream enriched with H₂S for the Claus unit and another stream high purity CO₂ stream suitable for compression and sequestration. However, this absorption process is typically limited to a CO₂ capture to around 70%.

A new type of membrane, which preferentially permeates CO2 over other gases including H2S, presents a promising opportunity for use in acid gas streams to enrich the H2S in the acid gas stream, while simultaneously capturing CO2. By integrating this membrane with the H₂S-selective amine, the CO₂ capture rate of can be increased to over 90%. Since the membrane is not constrained by equilibrium limitations, it can generate a residue stream with more than 90% H₂S, which can be directed to the Claus unit. The CO₂-rich permeate is subsequently treated in an H₂S-selective amine unit to capture CO₂. Hence, this process is referred to as Membrane-Acid Gas Enrichment (MAGE).

This membrane technology was successfully piloted and demonstrated stable performance throughout a field test lasting over 4,500 hours of operation. It is now set to be demonstrated in an oil refinery to further validate its potential.

Conclusion: This innovation has the potential to significantly improve CO₂ capture and H₂S enrichment, leading to more sustainable gas treatment operations. By integrating this specialized membrane with H₂S-selective amines offers a unique solution for enhancing CO2 capture and increasing the H₂S content in acid gas streams, paving the way for more efficient industrial practices.