Verification of a CO2 volumetric adsorption system
Date
2013-07-15
Authors
Maphada, Mulanga
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Carbon dioxide (CO2) atmospheric emissions are regarded as the major cause of
global climate change. South Africa aims to reduce its current emissions of over 400
Mton per annum through carbon dioxide capture and storage (CCS) technology by
initially implementing the storage phase. Storage of captured CO2 into various sites
(such as coal, rocks, aquifers and etc) is a globally accepted means to mitigate the
accumulation of greenhouse gases (GHG) in the atmosphere.
Before storing CO2, adsorption isotherms must be generated using a volumetric
adsorption system (VAS). A VAS is used to determine the CO2 storage capacity of
coal, and other materials, by monitoring the uptake of a known amount of CO2 under
pressure, generating adsorption isotherms. This research aims to commission and
verify the reliability of a VAS constructed at the University of the Witwatersrand,
Johannesburg, by in-house and external repetitive adsorption tests - using CO2 as
an adsorbate and a homogeneous Witbank basin bituminous coal sample as an
absorbent, in pressure steps from 10 bar up to 50 bar.
The operating procedure for the VAS is detailed. The average adsorption of the (inhouse)
repeatability runs was 0.0411 g CO2 per g coal (at 50 bar). The interlaboratory
comparison run from an external lab at Aachen University of Technology
had maximum adsorption capacity of 0.0250 g CO2 per g coal. The difference in
values is due to a variety of reasons, but essentially can be concluded that the VAS
is able to generate CO2 adsorption isotherms.