Engineering

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Now showing 1 - 10 of 438
  • (2006) Ho, Minh; Allinson, G; Wiley, Dianne
    Journal Article
    The sequestration of CO2 as a greenhouse mitigation option is becoming an increasingly important priority for industry. Theoretically membrane based CO2 removal systems have the potential to provide a cost effective, low maintenance approach for removing CO2 from gas streams. This study examines the effect of membrane characteristics, operating parameters and system design on sequestration costs for any source-sink combination. The total sequestration cost per tonne of CO2 avoided for separation, transport and storage are compared for the separation of CO2 from a black coalfired power plant in Australia. The results show that the membranes currently available have a total sequestration cost of US$55-61/tonne CO2 avoided. Lower costs for CO2 avoided can be achieved using an MEA amine based absorption separation system. Gas separation membranes would require significant improvements in CO2 permeability and selectivity, together with reductions in the cost of membranes and changes to the process configurations and operating pressures to be competitive against MEA systems for the purposes of geo-sequestration.

  • (2004) Ho, Minh; Wiley, Dianne
    Conference Paper
    The capture and storage of CO2 (CCS) as a greenhouse mitigation option is becoming an increasingly important priority for Australian industry. Membrane based CO2 removal systems can provide a cost effective, low maintenance approach for removing CO2 from gas streams. This study examines the effect of membrane characteristics and operating parameters on CCS costs using economic models developed by UNSW for any source-sink combination. The total sequestration cost per tonne of CO2 avoided for separation, transport and storage are compared for the separation of CO2 from coal fired power plants and natural gas processing. A cost benefit analysis indicates that sequestration of gases of high purities are dominated by compression costs which can be off-set by utilising membranes of higher selectivity coupled with higher permeability to reduce the required transmembrane pressure.





  • (1990) Xue, Sheng
    Thesis
    Gas flow in coal was studied in the laboratory to investigate the variation of coal permeability with changes in seam gases and confining stress with the aim of better understanding the properties of gas flow in coal seams. In addition to some modifications of the experimental apparatus, an extensive gas flow measuring and monitoring program in coal samples was carried out in a five-cell semi-automated triaxial stress test rig developed jointly by the Department of Mining Engineering and the Department of Industrial Chemistry at the University of New South Wales. Three gases, namely, nitrogen, methane and carbon dioxide, were used to investigate the effect of gas adsorption on permeability of coal from the Bulli seam. It was found that this coal has the highest permeability to nitrogen, methane has an intermediate value and carbon dioxide has the lowest value. This sequence is inversely proportional to the adsorption capacity of coal to each gas. This conclusion can also be applied to the samples which were subjected to triaxial stresses. The experimental results showed that the value of coal permeability ranged from 0.0029 mD to 10.68 mD without confining stress and that the Klinkenberg effect applied well to coal samples in a range of mean gas pressures from 0 to 20 atm. The effect of triaxial stress on coal permeability is quite obvious from the experimental results. Most of the coal samples had one to two orders of magnitude decrease in permeability as the confining stress was increased from 10 atm to 150 atm. The relationship between the permeability of coal to a mixture of methane and carbon dioxide, and its permeability to methane and carbon dioxide separately was established theoretically. It was found that the difference between theoretical calculations and experimental results was less than 15%.