Abstract
Capture conditions for CO2 vary substantially between industrial point sources. Depending on CO2 fraction and pressure level, different capture technologies will be required for cost- and energy-efficient decarbonisation. For decarbonisation of shifted synthesis gas from coal gasification, several studies have identified low-temperature CO2 capture by condensation and phase separation as an energy- and cost-efficient option. In the present work, a process design is proposed for low-temperature CO2 capture from an Integrated Gasification Combined Cycle (IGCC) power plant. Steady-state simulations were carried out and the performance of the overall process, as well as major process components, were investigated. For the baseline capture unit layout, delivering high-pressure CO2 at 150 bar, the net specific power requirement was estimated to 273 kJe/kgCO2, and an 85% CO2 capture ratio was obtained. The impact of 12 different process parameters was studied in a sensitivity analysis, the results of which show that compressor and expander efficiencies, as well as synthesis gas separation temperature, have the highest impact on power requirements. Modifying the process to producing cold liquid CO2 for ship transport resulted in 16% increase in net power requirements and is well suited for capturing CO2 for ship transport.
Highlights
Carbon dioxide (CO2 ) capture conditions for large point sources within industry and power generation vary substantially
The results are complemented with a sensitivity analysis in which the impact of process parameters on the power requirement is evaluated and discussed
For the most complex plate-fin heat exchangers, feasible geometric designs were developed and their results implemented in the overall process model
Summary
Carbon dioxide (CO2 ) capture conditions for large point sources within industry and power generation vary substantially. Instead of further compressing the gaseous separation product and adding another cooling and condensing stage, as assumed in [12], they suggest adding a downstream physical absorption stage in order to obtain an overall CCR of 95% For this capture rate, the energy requirement was estimated to be reduced by roughly 50% relative to a capture process entirely based on physical absorption. Peampermpool et al [16] proposed a two-stage low-temperature separation process capturing CO2 from Texaco IGCC synthesis gas. The advantage of low-temperature CO2 separation schemes over physical solvents was exemplified by Mori and Forsyth [17], in a study investigating and benchmarking different process schemes for CO2 capture and H2S removal from synthesis gas in a 700–900 MW IGCC power plant. It must be emphasised that the low-temperature separation processes considered here differ from antisublimation processes such as those found in [21,22], referred to as cryogenic CO2 separation in the literature
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