Abstract
The main purpose of this study is to identify the optimum multistage compression strategies for minimising the compression and intercooler power requirements for pure CO2 stream. An analytical model based on thermodynamics principles is developed and applied to determine the power requirements for various compression strategies for pure CO2 stream. The compression options examined include conventional multistage integrally geared centrifugal compressors (option A), supersonic shockwave compressors (option B) and multistage compression combined with subcritical (option C) and supercritical liquefaction (option D) and pumping. In the case of determining the power demand for inter-stage cooling and liquefaction, a thermodynamic model based on Carnot refrigeration cycle is applied. From the previous study by [1], the power demand for inter-stage cooling duty was assumed to have been neglected. However, based on the present study, the inter-stage cooling duty is predicted to be significantly higher and contributes approximately 30% of the total power requirement for compression options A, C and D, while reaches 58% when applied to option B. It is also found that compression option C can offer higher efficiency than other compression strategies, while supercritical liquefaction efficiency is only marginally higher than that in the compression option A.
Highlights
Carbon Capture and Sequestration (CCS) has been proposed as a promising technology for mitigating the impact of CO2 emissions from manufacturing industry and power generation sources, such as coalburning power plants, on global warming [2]
To make such comparison we use the thermodynamic analysis method as described in Section 2.0 where the power demand for compression is calculated using rigorous equations accounting for real fluid behaviour of CO2
The present study describes the results of thermodynamic analysis of the power requirements for compression of pure CO2 stream captured in capture units at 1.5 to 151 bar pressure required for subsequent pipeline transportation
Summary
Carbon Capture and Sequestration (CCS) has been proposed as a promising technology for mitigating the impact of CO2 emissions from manufacturing industry and power generation sources, such as coalburning power plants, on global warming [2]. Long-distance onshore transportation of large quantities of CO2 can be most efficiently achieved using pipelines transmitting CO2 in the dense-phase at pressures typically above 86 bar [3], i.e. above the fluid critical point pressure [4]. Given the relatively low pressure of captured CO2 [5], the pipeline transportation would require additional facilities for compression of the stream.
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