CCS and Power Systems

Carbon Capture - Post-Combustion Capture

Novel Concepts for the Compression of Large Volumes of Carbon Dioxide

Performer: Southwest Research Institute

Project No: FC26-05NT42650


  • Phase I work identified two promising concepts: inter-stage cooling to achieve near-isothermal compression, and liquid CO2 pumping to 2200 psia. The latter concept initially compresses CO2 to 250 psia and then uses refrigeration to condense the CO2 to a liquid. The liquid CO2, which requires significantly less power to compress than gaseous CO2, is then pressurized to 2,200 psia with a considerable cost savings. Preliminary analysis indicates up to a 35 percent reduction in compression power is possible with the new concepts being considered.

  • Developed and tested an internally-cooled compressor diaphragm that removes the heat of compression between each impeller. A cooling jacket was designed around a state-of-the-art aerodynamic flow path that contained an optimally designed heat transfer enhancement without introducing additional pressure drop.

  • A compressor test rig was developed by retrofitting an existing centrifugal compressor installed in a closed loop test facility with the new cooled diaphragm. The diaphragms were fabricated to provide accurate aero-dynamic and cooling circuit geometry. The compressor was instrumented and tested; internal instrumentation was included to permit characterization of the stage performance, heat transfer, and pressure drop. The internally-cooled compressor tests demonstrated the effectiveness of the design, which exceeded expectations.

  • Conjugate heat transfer CFD models were developed and utilized for compressor design verification and optimization.

  • A new pump loop facility was designed and constructed, adapting an existing cryogenic turbopump for use on liquid CO2. The pump was proven to meet all project objectives in terms of both hydrodynamic and mechanical performance.

  • After further process modeling—taking into consideration actual pump performance and commercial proposals for the heat exchangers—the liquefaction/pumping approach was deemed less desirable than a pure semi-isothermal solution. Therefore, the decision was made to pursue the pure compression approach and further optimize the heat transfer of the cooled diaphragm.

  • A cooled diaphragm design was developed that may be applied to high pressures as well, making a pure compression approach with this technology feasible. The effort and project costs originally allocated to design and build the liquefaction plant will be applied to development and single-stage testing of a Generation 3 design employing compact heat exchanger technology.

  • Phase III is currently underway to develop a new, pilot-scale, multi-stage centrifugal compressor that contains the cooled diaphragm technology. The new pipe loop has been designed and major pieces of equipment are on order. Testing is scheduled for completion in March 2014.

Project Details