CO2CRC operated a pilot scale capture facility at the Otway National Research Facility from 2016 to 2019 designed to test and validate the performance of innovative adsorbent and membrane materials using natural gas from its own Buttress well.

Otway Capture Research

CO2 is a major contaminant in natural gas and its concentration varies with location. Many known reserves of natural gas are undeveloped due to the high CO2 content of these fields and the high cost associated with separating large quantities of CO2 from the gas using conventional gas sweetening technologies. Conventional methods for removing CO2 from natural gas based on chemical solvents are not ideally suited to such conditions because of the large amount of energy consumed in these processes. In addition to this, the large footprint of these conventional solvent systems makes it a challenge to deploy them in offshore and subsea environments. Developing new technologies at scale in the laboratory alone is prohibitively expensive due to the high pressure conditions, the volumes of gas involved and reproducing typical feed conditions. The capture pilot plant at the Otway National Research Facility was established to test and demonstrate CO2 capture from natural gas using membrane and adsorption technologies to deliver compact, robust, low energy and low cost CO2 separation technologies for high pressure and high CO2 content applications.

The capture skid was designed to operate at pressures of up to 90 bar and CO2 compositions between 15 to 70 vol% in the feed gas to mimic various gas field compositions. The plant operated with a two-bed pressure swing adsorption (PSA) unit (with intermittent feed intake to mimic a system with continuous feed) and three membrane units with the ability to inject trace components such as H2S to investigate the effects of impurities on the performance of the materials tested. The new materials tested included:

  • Novel zeolite adsorbent with enhanced kinetics by ion-exchange.
  • Flat sheet and spiral wound and CAP (Continuous Assembly of Polymers) membranes (Ultrathin composite membranes).
  • ZIF/Pebax based hollow fibre composite membranes.

 

Resulting Publications

Tao, L., et al., CO2 capture from high concentration CO2 natural gas by pressure swing adsorption at the CO2CRC Otway site, Australia. International Journal of Greenhouse Gas Control, 2019. 83: p.1-10
Link to publication reference

Three test campaigns were carried out to test the performance and robustness of the new materials and compare them against simulations current technologies. Campaign 1 involved the separation of CO2 from  bottled compressed natural gas using commercial adsorbent and membrane modules to enable bench marking data to be collected and to accomplish the proof-of-concept. In Campaign 2, natural gas from the Buttress-1 well was mixed with compressed natural gas to obtain the desired range of feed gas compositions and CO2 concentrations. Campaign 3 was undertaken to observe the effect of H2S (up to 200ppm), a common natural gas impurity on the separation performance of selected materials.

The objectives of the PSA research project were to identify and develop new adsorbents, measure their CO2 adsorption capacity and selectivity, and assess their behaviour under high pressure conditions. The capture skid provided an opportunity to investigate effects of operating parameters such as feed composition and pressure, desorption pressure and the presence of small amounts of H2S on the PSA performance.

The objectives of the membrane research project were to identify and develop membrane modules capable of maintaining stable and effective CO2/CH4 separation over time,demonstrate their tolerance to H2S and their robustness under varying temperatures and pressures.

The Otway capture project achieved the following outcomes:

  • Analysed the separation performance of CO2 and natural gas at high operating pressures of various adsorbents and membranes.
  • Assessed the performance of novel adsorbent materials with enhanced kinetics by ion-exchange and verified its performance against mathematical simulations and laboratory isotherms.
  • Completed PSA cyclic tests using the novel adsorbents.
  • Demonstrated stable membrane performance during continuous operations – CO2/CH4 selectivity was maintained during the test period with values similar to those observed in the lab pre-tests.
  • Observed superior CO2 permeate rates and moderate selectivity with the Pebax membrane embedded wit nano-particles.
  • Developed CAP membranes with improved permeance and able to sustain pressures as high as 20 bar without significant plasticisation.
The Otway capture research skid
The Otway capture research skid (2016- 2019)

Significant laboratory work was undertaken to identify and characterise suitable material for field testing.

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