Project Summary
There is currently very little quantitative data reported in the scientific literature relating to partitioning of trace elements in amine PCC systems.
The most comprehensive dataset in existence (at least in the public domain) is from a study made by the US DoE nearly ten years ago. The results of that investigation indicated that trace elements from coal combustion were likely to concentrate in the reclaimer waste of the amine plant.
Despite the lack of data, it is apparent that most trace elements will be removed from the system by particulate emission control systems before they enter the CO2 capture plant. However, volatile species, especially mercury, arsenic, selenium, along with fine particles not retained by the ESP (electrostatic precipitators) or fabric filter, have the potential to enter the CO2 capture system.
Because of the effectiveness of flue gas desulphurisation (FGD) at removing trace elements, the solid product and process water will be major points for trace element discharge.
The conclusions from the laboratory study showed that:
Apart from mercury, the selected elements are mostly retained within the Acid Gas Scrubber (AGS), with very little carry-over into the ASE (absorber/stripper).
Some elements also show concentration changes in the AGS solution, possibly reflecting corresponding changes in pH of the absorbent solution.
Mercury remains in a volatile phase passing through the system with very little or no retention.
There is some variability in trace elements deportment related to the nature of the solvent, which is most likely due to the pH of the absorbent, precipitation and to carbonate formation, during the course of the experiment.
The behaviour of the trace elements in the ASE, particularly in the stripper, most likely reflects the volatility of the selected trace elements and solubility in the solvent matrix.
