Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂
This paper presents a design strategy for very low flow coefficient multi-stage compressors operating with supercritical CO 2 for Carbon Capture and Sequestration (CCS) and Enhanced Oil Recovery (EOR). At flow coefficients less than 0.01 the stage efficiency is much reduced due to dissipation in th...
| Main Authors: | , , , |
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| Format: | Article |
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ASME International
2018
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| Online Access: | http://hdl.handle.net/1721.1/116056 https://orcid.org/0000-0003-2167-9860 |
| _version_ | 1811071417446301696 |
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| author | Casey, M. Lettieri, Claudio Baltadjiev, Nikola Dimitrov Spakovszky, Zoltan S |
| author2 | Massachusetts Institute of Technology. Gas Turbine Laboratory |
| author_facet | Massachusetts Institute of Technology. Gas Turbine Laboratory Casey, M. Lettieri, Claudio Baltadjiev, Nikola Dimitrov Spakovszky, Zoltan S |
| author_sort | Casey, M. |
| collection | MIT |
| description | This paper presents a design strategy for very low flow coefficient multi-stage compressors operating with supercritical CO 2 for Carbon Capture and Sequestration (CCS) and Enhanced Oil Recovery (EOR). At flow coefficients less than 0.01 the stage efficiency is much reduced due to dissipation in the gas-path and more prominent leakage and windage losses. Instead of using a vaneless diffuser as is standard design practice in such applications, the current design employs a vaned diffuser to decrease the meridional velocity and to widen the gas path. The aim is to achieve a step change in performance. The impeller exit width is increased in a systematic parameter study to explore the limitations of this design strategy and to define the upper limit in efficiency gain. The design strategy is applied to a full-scale re-injection compressor currently in service. Three-dimensional, steady, supercritical CO 2 CFD simulations of the full stage with leakage flows are carried out with the NIST real gas model. The design study suggests that a non-dimensional impeller exit width parameter b 2 * =(b2/R) φ of 6 yields a 3.5 point increase in adiabatic efficiency relative to that of a conventional compressor design with vaneless diffuser. Furthermore, it is shown that in such stages the vaned diffuser limits the overall stability and that the onset of rotating stall is likely caused by vortex shedding near the diffuser leading edge. The inverse of the non-dimensional impeller exit width parameter b 2 * can be interpreted as the Rossby number. The investigation shows that, for very low flow coefficient designs, the Coriolis accelerations dominate the relative flow accelerations, which leads to inverted swirl angle distributions at impeller exit. Combined with the two-orders-of-magnitude higher Reynolds number for supercritical CO 2 , the leading edge vortex shedding occurs at lower flow coefficients than in air suggesting an improved stall margin. |
| first_indexed | 2024-09-23T08:50:39Z |
| format | Article |
| id | mit-1721.1/116056 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T08:50:39Z |
| publishDate | 2018 |
| publisher | ASME International |
| record_format | dspace |
| spelling | mit-1721.1/1160562022-09-30T11:41:19Z Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂ Casey, M. Lettieri, Claudio Baltadjiev, Nikola Dimitrov Spakovszky, Zoltan S Massachusetts Institute of Technology. Gas Turbine Laboratory Massachusetts Institute of Technology. Department of Aeronautics and Astronautics Lettieri, Claudio Baltadjiev, Nikola Dimitrov Spakovszky, Zoltan S This paper presents a design strategy for very low flow coefficient multi-stage compressors operating with supercritical CO 2 for Carbon Capture and Sequestration (CCS) and Enhanced Oil Recovery (EOR). At flow coefficients less than 0.01 the stage efficiency is much reduced due to dissipation in the gas-path and more prominent leakage and windage losses. Instead of using a vaneless diffuser as is standard design practice in such applications, the current design employs a vaned diffuser to decrease the meridional velocity and to widen the gas path. The aim is to achieve a step change in performance. The impeller exit width is increased in a systematic parameter study to explore the limitations of this design strategy and to define the upper limit in efficiency gain. The design strategy is applied to a full-scale re-injection compressor currently in service. Three-dimensional, steady, supercritical CO 2 CFD simulations of the full stage with leakage flows are carried out with the NIST real gas model. The design study suggests that a non-dimensional impeller exit width parameter b 2 * =(b2/R) φ of 6 yields a 3.5 point increase in adiabatic efficiency relative to that of a conventional compressor design with vaneless diffuser. Furthermore, it is shown that in such stages the vaned diffuser limits the overall stability and that the onset of rotating stall is likely caused by vortex shedding near the diffuser leading edge. The inverse of the non-dimensional impeller exit width parameter b 2 * can be interpreted as the Rossby number. The investigation shows that, for very low flow coefficient designs, the Coriolis accelerations dominate the relative flow accelerations, which leads to inverted swirl angle distributions at impeller exit. Combined with the two-orders-of-magnitude higher Reynolds number for supercritical CO 2 , the leading edge vortex shedding occurs at lower flow coefficients than in air suggesting an improved stall margin. Mitsubishi Jūkōgyō Kabushiki Kaisha. Takasago R&D Center 2018-06-04T15:59:52Z 2018-06-04T15:59:52Z 2013-06 2018-04-11T14:03:02Z Article http://purl.org/eprint/type/ConferencePaper 978-0-7918-5524-9 http://hdl.handle.net/1721.1/116056 Lettieri, C., N. Baltadjiev, M. Casey, and Z. Spakovszky. “Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO2.” Volume 6C: Turbomachinery (June 3, 2013). https://orcid.org/0000-0003-2167-9860 http://dx.doi.org/10.1115/GT2013-95012 Volume 6C: Turbomachinery Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf ASME International ASME |
| spellingShingle | Casey, M. Lettieri, Claudio Baltadjiev, Nikola Dimitrov Spakovszky, Zoltan S Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂ |
| title | Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂ |
| title_full | Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂ |
| title_fullStr | Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂ |
| title_full_unstemmed | Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂ |
| title_short | Low-Flow-Coefficient Centrifugal Compressor Design for Supercritical CO₂ |
| title_sort | low flow coefficient centrifugal compressor design for supercritical co₂ |
| url | http://hdl.handle.net/1721.1/116056 https://orcid.org/0000-0003-2167-9860 |
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