CO2 compression

Southwest Research Institute (SwRI) has received a $9.9 million award from the U.S. Department of Energy for Phase 3 work of a CO2 compression project. This phase is to design and test carbon dioxide compression using technologies developed under previous DOE phases of the improved compression technologies program.

The project consists of the design, construction and testing of a full-scale, multi-stage centrifugal compressor with internal cooling that is being co-funded by Dresser-Rand and SwRI, and a CO2 liquefaction plant and a liquid pumping station that was developed by SwRI under a previous project. SwRI researchers found this arrangement to be the lowest power means to boost the pressure of carbon dioxide emissions from pulverized coal, integrated gasification combined cycle (IGCC) and oxy-fuel power plants.

Because of growing concern over greenhouse gas emissions, the U.S. government and utilities are developing technologies to separate CO2 both pre- and post-combustion. However, because of compression power requirements the penalty for CO2 sequestration is significant — as much as 10 percent of a power plant’s energy output. Reducing the power requirement would improve overall plant efficiency and encourage sequestration of CO2 at existing power plants and for future plant designs.

Under previous funding from DOE and industry partners, SwRI researchers investigated novel compression concepts that would boost the pressure of CO2 to pipeline pressure levels with a minimal amount of energy required.

“Because the high-pressure ratio compression of CO2 results in significant heat, we had to develop a method that would compress CO2 while removing the resulting heat,” said Dr. J. Jeffrey Moore, a program manager in SwRI’s Mechanical Engineering Division and manager of the DOE effort. “Because less energy is required to boost the pressure of a cool gas, interstage cooling is desirable.”

To accomplish that, Phase 2 of the program, recently completed, evaluated the performance of these devices using two SwRI designed and developed experimental test rigs, including a new liquid CO2 pump test facility.

“The internally cooled compressor met our design objectives and can result in up to a 20 percent savings over a standard compressor,” Moore said. “The turbopump met all performance and mechanical objectives.”

Once the project proves the integration of the technology, SwRI and its partners will pursue a field installation site.

The SwRI design differs from CO2 compressors introduced by MAN Turbo & Diesel is that the SwRI design cools the diaphragms that make up the aerodynamic flow path of the compressor.  The MAN design placed small heat exchangers inside the casing.