September 29, 2010 — Engineers at Southwest Research Institute® (SwRI®) have completed testing of a high-pressure turbo pump and an enhanced compressor design for sequestration 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, the penalty for CO2 sequestration because of compression power requirements is significant — as much as 10 percent of a power plant's output, increasing the cost of electricity by 20 to 80 percent. Reducing the power requirement would improve overall plant efficiency and encourage sequestration of CO2 at existing power plants and for future plant designs.
Under funding from the U.S. Department of Energy 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 of compression, 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."
SwRI's solution to the problem is a liquid CO2 turbo pump and an internally cooled compressor diaphragm. To evaluate the performance of these devices, SwRI engineers designed and developed two experimental test rigs, including a new liquid CO2 pump test facility.
"Preliminary results indicate that we can achieve up to a 25 percent reduction in compression power requirements with pure compression using an isothermal process with the internally cooled compressor diaphragm," Moore said. "Our liquid turbo pump approach can achieve as much as a 30 percent reduction, but more work is required to develop it. We believe combining both technologies could lead to a reduction of 35 percent over currently available technology."
SwRI is actively pursuing a field installation site to obtain field performance tests for this technology.
For more information, contact SwRI Solutions.