Hall G, 1st pm, Day 4 Thursday Abstracts

Session S7. Carbon capture, utilization, and storage (CCUS)

The CO₂ separation technology is considered to play a key role to reduce or control the CO₂ emission from the fossil fuel, especially from coal in the world. Australia, rich in coal resources, is also facing “De-carbonization trend” and thus technical solutions are needed.
In Australia, we launched an internationally collaborative PCC (Post Combustion Capture) demonstration project in 2014. The name of the project is the abbreviation of PCC, and IHI (Japanese engineering company), CSIRO (Australian research institute), AGL (Australian power company), the partners of the project.
Prior to the project, we had developed IHI advanced CO₂ captured system with 20 ton CO₂/day scale pilot plant in Japan, which mainly consists of the IHI Solution No.162 (ISOL-162), the advanced packing material and the advanced process enabling to significantly reduce the solvent regeneration energy.
Through the long term operation at this demonstration project under the practical conditions, i.e., using the flue gas of an operating brown coal-fired power plant, we have evaluated our integrated PCC technologies. During the operation, 90 % CO₂ capture ratio was achieved stably and other measured values were also kept stable. The results indicate that the PICA plant and the ISOL-162 solvent have sufficient stability and robustness to enable long term operation.
IHI has improved the design and refined operation to provide a robust and environmentally friendly PCC system based on the knowledge and technologies obtained through the ISOL-162 long-term operation using the PICA pilot plant and parallel research activities.
Over the long term operation, practical studies of the emission evaluation were carried out. The emissions of amine and its derivatives from the outlet of the washing tower were measured on various wash-type conditions. The result clearly demonstrated that the amine emission from the system was considerably reduced and minimized by the application of the washing technologies. The demonstration results are explained in detail in the presentation.

Indirect carbon sequestration via mineralization has been perceived as an alternative solution to address increasing anthropogenic emissions. Ex situ mineralization, in contrast with the in situ counterpart, has been the focus of recent studies as it provides a faster and more efficient carbon capture process due to the addition of a leaching step that releases the ions available for intimate contact with carbon dioxide. Mixed dump serpentenite samples from a Nickel mine site in Mindanao, Philippines were characterized through leaching tests to determine their viability in carbon sequestration. Ground samples of 75-150 microns particle size were leached with hydrochloric acid concentrations of 1 M, 2.5 M, and 4 M, at temperatures of 50C, 75C and 100C. The reaction time was also set at 1 hr, 2.5 hrs, and 4 hrs, respectively. The optimum set of conditions were then determined by analyzing the extraction efficiencies of Mg, Fe, Si, Ca, and Al ions from the aforementioned set of parameters, using the Face-Centered Cube model for Response Surface Methodology. Prior to leaching, XRD, XRF, and ICP-MS analyses were performed to determine the dominant minerals and elemental composition of the sample. The morphology and crystal structure of the optimum and non-optimum samples were also confirmed by BET and SEM analyses to establish the relationship of the crystal structure of the media to the ion extraction efficiencies.

Efficient and economical CO₂ capture from coal-fired power plants is a major challenge for the application of CCS concept as this step incurs primary cost and energy penalty. Oxy-fuel combustion and post-combustion CO₂ capture using Amine process are few approaches but are energy intensive. Chemical Looping Combustion (CLC) technology where oxygen for combustion is supplied by metal oxygen carriers instead of air is finding application in coal fired power plants for its economical CO₂ capture. The oxygen carrier is circulated between the two reactors, Fuel reactor and Air reactor which usually operate under fluidized bed conditions. The flue gases from Fuel reactor contain CO₂ and H₂O which can be easily separated leading to nearly pure CO₂ and thus reducing the energy requirement for CO₂ separation. Therefore, development of a robust, effective and economical metal oxygen carrier is of primary research interest. This study reports and compares the reduction-oxidation characteristics of several oxygen carriers. Basic reduction-oxidation experiments were carried out in a small fluidized bed reactor by switching gases. Effect of reduction temperature, gas residence time, and type of oxygen carrier on conversion efficiency was investigated. Results were discussed in terms of their physical characteristics, oxygen capacity, oxygen release rate and stability after repeated redox cycles. A first order reaction was applied to analyse the reduction kinetics. The study also reports long run performance results of a 100kW scale circulating fluidized bed bench scale CLC unit developed at AIST under NEDO project.

A novel process named a membrane flash process was studied to realize an energy-saving technology and to substitute it for a conventional process using steam for regeneration of the CO₂ absorbent liquids in CCS. In this study, four different amine-based absorbents (MEA, DEA, MDEA, MDEA and piperazine (PZ)) were tested to find an absorbent favorable for the membrane flash process using an alumina microporous hollow fiber membrane.
CO₂ rich solution of each absorbent was supplied into the tube side of the hollow fiber and the pressure on the shell side was reduced so that the pressure difference between the tube and shell sides was 45, 65, 85 and 95 kPa. The absorbent liquid was forced to permeate through the pores of the membrane and CO₂ was released during and after permeation. MEA showed the highest liquid permeation rate while MDEA+PZ showed the lowest permeation rate. DEA and MDEA had the similar permeation rates. On the other hand, the highest CO₂ desorption rate was obtained with MDEA+PZ and the second was obtained with MEA. As a result, the CO₂ release ratio, which was defined as the ratio of actually desorbed CO₂ amount to the potentially releasable CO₂ amount, was highest with MDEA+PZ while MEA showed the lowest CO₂ release ratio. The energy requirement for CO₂ desorption consisting of the energy items required for liquid permeation, gas discharge and reaction heat was estimated based on the experimental results for each absorbent. The results indicated that the energy requirement was smallest in the case of MDEA+PZ. From these results, it has been found out that MDEA+PZ was most suitable for the membrane flash process.

In this research work, carbon nanofibers (CNFs) were initially synthesized and then post-coated on honeycomb monolith substrates using injection chemical vapor deposition (ICVD) technique. The synthesized CNF monolith was intended for CO₂ adsorption study. The effect of various wash-coated materials and catalyst promoter on the growth rate of CNFs on monolith substrates were examined. The characteristics of the synthesized CNFs-coated monolith composites were examined using Raman spectroscopy, Brunauer–Emmett–Teller (BET), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), and Transmission electron microscopy (TEM) techniques. According to the textural characterization study, the specific surface area and pore volume of CNFs-coated monolith composites were significantly improved as compared to bare monolith which might be attributed to the growth of highly pure and aligned CNFs over monolith substrate. Besides that, the synthesized CNFs-coated monolith possessed extremely well thermal stability up to the temperature of 550 °C which was corresponded to the strong attachment of highly graphitized CNFs over monolith substrates.