Development and Testing of Multi-Stage Internally Cooled Centrifugal Compressor
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In order to reduce the amount of carbon dioxide (CO2) released into the atmosphere, significant work has been completed to enable the capturing and storing of CO2 from power plants and other major producers of greenhouse gas emissions. The compression of the captured carbon dioxide stream requires significant amounts of power, which impacts plant availability and operational costs. Preliminary analysis has estimated that the CO2 compression process reduces typical power plant efficiency by 8% to 12%. The work presented in this paper supports the U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) objectives of reducing the energy requirements for carbon capture and storage in electrical power production. The primary objective of this study is to boost the pressure of CO2 to pipeline pressures with the minimum amount of energy required. Previous thermodynamic analysis identified optimum processes for pressure rise in both liquid and gaseous states. Isothermal compression is well known to reduce the power requirements by minimizing the temperature of the gas entering subsequent stages. Intercooling is typically accomplished using external gas coolers and integrally geared compressors. For large scale compression, use of straight through centrifugal compressors, similar to those used in oil and gas applications including LNG production, is preferred due to the robustness of the design. However, external intercooling between each stage is not feasible. The current research develops a multi-stage internally cooled compressor diaphragm that removes heat internal to the compressor and leverages the previous work on a single stage cooled diaphragm. Experimental demonstration of the design was performed on a full-scale 3 MW, 6-stage back-to-back centrifugal compressor operating in a closed loop test facility over a range of operating conditions. This work is a full scale implementation of the previous single-stage cooled diaphragm test program of Moore, et al. (2011). A multi-stage cooled diaphragm design was implemented in the current work and improvements to the mechanical strength and manufacturing process were made. Testing with a high speed torque-meter provides direct comparisons between adiabatic (no cooling) and with cooling configurations.
Kerth, Jason; Pacheco, Jorge; Moore, Jeffrey; Allison, Tim; Evans, Neal (2015). Development and Testing of Multi-Stage Internally Cooled Centrifugal Compressor. Turbomachinery Laboratories, Texas A&M Engineering Experiment Station. Available electronically from