Aerosol growth in CO2 absorption with MEA, modelling and comparison with experimental results

A new and improved aerosol model has been developed and tested against experimental data. An e-NRTL equilibrium model for MEA was extended to cover sulphuric acid containing droplets and validated against new eboulliometer data in this work. The droplet model predicts emissions without demister installed in the absorber, within ± 20% and with demister, 30-80% of the measured emissions. The model predicts well the change in emissions from NG-based to coal-based exhaust. Under conditions reported in this work, the droplet number concentration was found to have a small effect on predicted emissions because of more MEA gas-phase depletion with high droplet concentrations and slower growth. The effects counteract each other. With significant MEA depletion in the gas phase, the emissions are largely determined by the mass transfer rate from the bulk liquid. The initial droplet sulphuric acid concentration had a minor effect on the outlet droplet size distribution. The effect on MEA emissions was significant: the emissions went up with increased initial sulphuric acid concentration. The effect of sulphuric acid was stronger for low inlet gas CO2 concentration (NG) than for coal-based exhaust. The increase in emissions is believed to be caused by the increase in overall driving force for MEA between bulk liquid phase and droplets. The log-normal model does not catch small inlet droplet sizes in the range below 20-30nm. These droplet sizes hardly grow in the absorber and water wash and in the total emissions, these droplets have a negligible impact on emissions.publishedVersio

Aerosol growth in CO2 absorption with MEA, modelling and comparison with experimental results

A new and improved aerosol model has been developed and tested against experimental data. An e-NRTL equilibrium model for MEA was extended to cover sulphuric acid containing droplets and validated against new eboulliometer data in this work. The droplet model predicts emissions without demister installed in the absorber, within ± 20% and with demister, 30-80% of the measured emissions. The model predicts well the change in emissions from NG-based to coal-based exhaust. Under conditions reported in this work, the droplet number concentration was found to have a small effect on predicted emissions because of more MEA gas-phase depletion with high droplet concentrations and slower growth. The effects counteract each other. With significant MEA depletion in the gas phase, the emissions are largely determined by the mass transfer rate from the bulk liquid. The initial droplet sulphuric acid concentration had a minor effect on the outlet droplet size distribution. The effect on MEA emissions was significant: the emissions went up with increased initial sulphuric acid concentration. The effect of sulphuric acid was stronger for low inlet gas CO2 concentration (NG) than for coal-based exhaust. The increase in emissions is believed to be caused by the increase in overall driving force for MEA between bulk liquid phase and droplets. The log-normal model does not catch small inlet droplet sizes in the range below 20-30nm. These droplet sizes hardly grow in the absorber and water wash and in the total emissions, these droplets have a negligible impact on emissions

Aerosol growth in CO2 absorption with MEA, modelling and comparison with experimental results

A new and improved aerosol model has been developed and tested against experimental data. An e-NRTL equilibrium model for MEA was extended to cover sulphuric acid containing droplets and validated against new eboulliometer data in this work. The droplet model predicts emissions without demister installed in the absorber, within ± 20% and with demister, 30-80% of the measured emissions. The model predicts well the change in emissions from NG-based to coal-based exhaust. Under conditions reported in this work, the droplet number concentration was found to have a small effect on predicted emissions because of more MEA gas-phase depletion with high droplet concentrations and slower growth. The effects counteract each other. With significant MEA depletion in the gas phase, the emissions are largely determined by the mass transfer rate from the bulk liquid. The initial droplet sulphuric acid concentration had a minor effect on the outlet droplet size distribution. The effect on MEA emissions was significant: the emissions went up with increased initial sulphuric acid concentration. The effect of sulphuric acid was stronger for low inlet gas CO2 concentration (NG) than for coal-based exhaust. The increase in emissions is believed to be caused by the increase in overall driving force for MEA between bulk liquid phase and droplets. The log-normal model does not catch small inlet droplet sizes in the range below 20-30nm. These droplet sizes hardly grow in the absorber and water wash and in the total emissions, these droplets have a negligible impact on emissions

Inhibition of fungal plant pathogens by synergistic action of chito-oligosaccharides and commercially available fungicides

Chitosan is a linear heteropolymer consisting of β 1,4-linked N-acetyl-D-glucosamine (GlcNAc) and D-glucosamine (GlcN). We have compared the antifungal activity of chitosan with DPn (average degree of polymerization) 206 and FA (fraction of acetylation) 0.15 and of enzymatically produced chito-oligosaccharides (CHOS) of different DPn alone and in combination with commercially available synthetic fungicides, against Botrytis cinerea, the causative agent of gray mold in numerous fruit and vegetable crops. CHOS with DPn in the range of 15-40 had the greatest anti-fungal activity. The combination of CHOS and low dosages of synthetic fungicides showed synergistic effects on antifungal activity in both in vitro and in vivo assays. Our study shows that CHOS enhance the activity of commercially available fungicides. Thus, addition of CHOS, available as a nontoxic byproduct of the shellfish industry, may reduce the amounts of fungicides that are needed to control plant diseases

Quantification of Aqueous Monoethanolamine Concentration by Gas Chromatography for Postcombustion Capture of CO 2

The availability of reliable analytical methods for measuring amine concentrations is necessary for optimum operation of aqueous amine CO 2 separation systems being employed for postcombustion capture (PCC) of CO2. A GC-FID (gas chromatography with flame ionization detection) method is described for the reliable quantification of 30% (w/w) monoethanolamine (MEA) in severely degraded solvent samples. The observation of intermittent splitting of the MEA peak was a major concern with this approach. The use of a wide-bore column led to improved MEA peak resolution and peak shape. The reliability and robustness of the GC-FID method were assessed by analyzing degraded 30% (w/w) MEA solvent samples from CSIRO's pilot plant at AGL's Loy Yang power station in Victoria, Australia. The results were compared with those obtained by titration and total organic carbon (TOC) measurements of the same samples. The MEA concentrations obtained by the GC-FID and titration methods were statistically similar. In contrast, the MEA concentrations calculated from TOC were consistently higher than those obtained by both GC-FID and titration. © 2014 American Chemical Society