Following the previous project 6-0710-0061 on the work of feasibility of cleaning mercury gases from oxyfuel flue gas in a fabric filter and during CO2 compression, this project aims to quantify the extent of mercury removal and the impact of other gas impurities in the CO2 to reduce the cost and risk associated with CO2 gas quality in demonstration projects. The project consists of two components: laboratory experiments and field tests in the Callide Oxyfuel Project. With the combination of the two components, a better understanding will be provided on the impact of mercury capture.
Key findings from this final report are that:
- Greater Hg and S capture occurs if fabric filter ash has a lower carbon content, i.e. is ‘clean ash’;
- Where possible, oxyfuel processing units should operate at a temperature over the acid dew point temperature to avoid acid attack.
- Under these conditions, the fabric filter can reduce mercury levels in CO2 rich gas to 0.01 μg/m3. This, combined with the reduction of up to 100% SOx and 80% NOx levels, avoids the need for costly unit operations in the power plant or CO2 processing unit.
The results of two trials at the Callide Oxyfuel Project have validated these results.