Project Summary

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.

Available Reports

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Mercury capture by fabric filter and CPU in oxyfuel technology

The present project quantifies the extent of removal and the impact of impurity levels in the CO2 with laboratory experiments on ‘synthetic’ oxyfuel gas and with two trials at the Callide Oxyfuel Project (COP) to test the impact of ‘real’ oxyfuel gas. The COP tests included experiments over the fabric filter, samples taken directly from the CO2 processing unit (CPU) as well as compressed sampled (slip stream) gases and resulting liquids from an apparatus developed for compression of oxyfuel flue gas using a piston compressor.

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Appendix 3: Formation of nitrogen containing gases under high pressure during compression of oxyfuel gas: a subcontract from the University of Newcastle to Macquarie University

Infrared spectroscopy was used to study the formation of nitrogen based oxides and acids during compression of gas approximating the composition of trace nitrogen species in oxy-fuel flue gas. Previous work has shown that higher pressure converts insoluble NO in the flue gas to NO2, however the nitrogen chemistry is complicated by the presence of water (as a vapour and a liquid) potentially forming N2O4, HONO and HNO3. The final form of nitrogen was expected to have an impact on where the material reported to in the system and thus have the potential to affect the overall mass balance. Experiments were undertaken at both Macquarie University and at the University of Newcastle to investigate the impact of pressure in dry and wet conditions.

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Appendix 2: Mercury removal in oxyfuel flue gas compression, product characterisation and experiments at the Callide Oxyfuel Project

This report has investigated the mercury removal during compression of oxy-fuel flue gas at the Callide Oxy-fuel Project (COP).

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Appendix 1: Mercury removal and acid dew point temperature reduction due to SO3 capture by ash in the fabric filter of oxy-fuel technology

This report specifically details the research work undertaken to quantify and provide understanding of the impact (reduction) of Hg capture due to SO2/SO3 with associated high acid dew point temperature by ash in the fabric filter in oxyfuel combustion

Project Name:
Gas quality impacts, assessment and control in oxy-fuel technology for CCS: Part 2. Mercury removal with SO3 in the fabric filter and with NOX as liquids in CO2 compression

Research Organisation:
The University of Newcastle

Status:
Completed, 2015

Authors:
Terry Wall, Rohan Stanger, Lawrence Belo, Kalpit Shah, Tim Ting, and Liza Elliott

Reference:
6-1212-0221

Research Program: Oxyfuel
Demonstration: Callide Oxyfuel
Research Focus: Oxyfuel

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