https://doi.org/10.1016/j.clet.2021.100249
“One of the most important drawbacks of amine-based PCC technologies is the high energy consumption that can increase significantly when combined with CO2 compression (Le Moullec and Kanniche, 2011a). In order to reduce the energy demands (i.e., the required heating and cooling duties) of PCC processes, researchers have put a great deal of effort to date into developing more efficient designs and solvents. Nevertheless, an extensive investigation into both the thermodynamic and economic feasibility of the modifications has not been done yet. For instance (Goto et al., 2013), reviewed the efficiency penalties of integrating a PCC unit into a coal-fired power plant and reported that the PCC technology accounts for two thirds of the total efficiency penalty of the combined operations. Research studies that have attempted to minimize this energy penalty fall into two main categories: modifications of the process configurations and development of new solvents (Feron, 2016). These process modifications consist of the 16 patented/licensed technologies that are listed in Table 1.
Table 1. Process modifications scenarios for amine-based PCC (Cousins et al., 2011), Courtesy of CSIRO.
| Process modification scenario | Basis of study | Potential savings | Proposed changes to process design |
|---|---|---|---|
| Inter-stage temperature control absorber | Modelling | 56% reduction in reboiler duty | Cooler, heat exchanger, overhead heat exchanger, pumps |
| Heat integrated stripper | Plant data and some modelling | 33–50% lower energy consumption | Remove lean/rich heat exchanger, add novel stripping column with integrated heat exchangers, pumps |
| Multi-component stripper column | Reduced waste stream from pre-treatment column | Recirculation tank, cooler on caustic stream, pumps | |
| Solvent-based laboratory data | Reduced solvent degradation | SO2 stripper, lean/rich heat exchanger on solvent regeneration, SO2 stripper reboiler, pumps |
|
| Split flow process(on lean/rich amine streams) | Experimental data and modelling | 50% lower steam consumption | Heaters, semi-lean/rich heat exchanger, semi-lean cooler, pumps |
| Improved split flow process | Modelling | 70% energy savings over standard split flow | Side-draw reboiler, semi-lean cooler, flash tank, side stripper, pump |
| Modelling | Savings with power station integration | Semi-lean cooler, modified lean/rich heat exchanger, condensate flash drum, throttling valve, semi-lean regenerator, pump | |
| Condenser and reboiler duties reduced by 30% and 20%, respectively | Ultra-lean cooler/solvent reboiler, multi-stage stripper, rich and lean solvent stream split, pump | ||
| Rich stream split | Calculation | 10% reduction in reboiler duty | Rich stream split |
| Vapor recompression (on rich amine stream) | Modelling | 24% reduction in reboiler duty | Compressor, resized reboiler (possible) |
| Modelling | Reduced steam demand by 11%, power costs by 5%, and stripper diameter by 6% | Compressor, lean/rich heat exchanger, flash drum, pump | |
| Multi-pressure stripping | Modelling | 8% reduction in equivalent work | Compressors, novel multi-pressure stripper |
| Matrix stripping | Modelling | 15–30% reduction in reboiler duty | Additional columns (some-multi-stage), rich stream split, lean/rich heat exchanger, overhead coolers, reboiler, pumps |
| Heat Integration | 6.8% reduction in reboiler duty | Integration with boiler flue gas, heat exchangers, pumps | |
| Modelling | 30% reduction in reboiler duty | Bypass on rich/lean heat exchanger, filter flash tank | |
| 39% reduced steam consumption | Condensate drum, heat exchangers, rich solvent cooler, pumps |
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