Pilot-Scale Development of a PEEK Hollow Fiber Membrane Contactor Process for Post-Combustion CO2 Capture

A novel poly(ether ether ketone) (PEEK) hollow fiber membrane technology for carbon dioxide capture from flue gases has been developed. The process combines advantageous features of both absorption and membrane processes to cost-effectively separate and capture CO₂ from emission sources. In this process, CO₂-containing flue gas passes through one side of the hollow fiber membrane contactor (HFMC), while a CO₂ selective solvent flows on the other side. CO₂ permeates through the hollow fiber membrane pores and is chemically absorbed into the solvent. The CO₂rich solvent is regenerated and sent back to the membrane absorber.

Supported by the US Department of Energy (Office of Fossil Energy’s National Energy Technology Laboratory), the objectives of our pilot-scale development program were to build a 0.5 MW_e equivalent pilot-scale CO₂ capture HFMC system, conduct tests on flue gas at the National Carbon Capture Center (NCCC) and demonstrate a continuous, steady-state operation for a minimum of two months. Under this program, the PEEK HFMC technology was scaled from the bench scale to a pilot scale utilizing larger size HFMC modules. The modules measured 8-inches in diameter by 5 feet long with a membrane surface area of about 40 m² per module. These modules have shown exceptionally high CO₂ capture rates due to the high membrane intrinsic CO₂ permeance as well as the structured PEEK hollow fiber module configuration. In our study, CO₂ gas permeance of 2,150 GPU [1 GPU = 10^-6 cm³(STP)/(cm²×s·cmHg)] was attained by optimizing the membrane preparation procedures. By using aMDEA solvent and a simulated flue gas, the HFMC showed greater than 90% CO₂ removal with 98% CO₂ productpurity. The mass transfer coefficient was 2.0 (sec)^-1.

Construction of the 0.5 MW_e equivalent CO₂ capture system was completed and shipped to the NCCC. We are currently installing the pilot plant. It is anticipated that the parametric tests will be completed by September 2017, and the continuous, steady-state operation for a minimum of two months will be completed by June 2018. After the current project, we plan to complete a 10 MW_e equivalent CO₂ capture system demonstration (200 Tonne/day) by 2022. Currently, we are also developing a transformational hybrid process combining a gas separation membrane configuration unit and PEEK HFMC unit that can further reduce the CO₂ capture cost.