AN EXERGY ANALYSIS FOR MINERAL CARBONATION

Magnesium oxide-based minerals such as serpentine and olivine may be used for long-term storage of CO2, from combustion of fossil fuels or industrial processes such as steel works, in the form of magnesium carbonate. Large resources of suitable minerals appear to exist in Finland and at many other locations worldwide. The efficiency of the mineral carbonation process can be evaluated using exergy analysis, which will allow for comparing different mineral deposits that are characterised by different composition and quality. Other factors that play a role are the temperature and pressure, the presence of other gases besides CO2 and the degree of magnesium carbonation that is reached. Important for the analysis is the calculation of the standard chemical exergy of the chemical species involved

CO 2 capture, storage and reuse potential in Finland

Abstract Economical feasibility and potential of CO 2 capture, storage and reuse in Finland was evaluated under the National Programme on Technology and Climate Change (Climtech). In Finland, no suitable geologic formations exist to sequester CO 2 . The nearest potential CO 2 sequestration sites are offshore oil and gas fields in the North Sea and Barents Sea, which would mean a transport of 500-1000 km for captured CO 2 . With current knowledge, capturing CO 2 near the storage sites and investing to new cross-border electricity transmission capacity seems the most feasible option for Finland. Storing CO 2 as solid mineral carbonate could be an option in the future, since large resources of suitable silicates exist in Finland as natural minerals and as wastes of mining industry. The reuse potential of captured CO 2 is less than 0.5% of the annual CO 2 emissions.

Mercury in waste in the European Union : sources, disposal methods and risks

http://www.elsevier.com/locate/issn/09213449Over the recent decades, there has been widespread concern regarding the toxic impact of mercury (Hg) in the ecosystem due to its mobility, volatility and potential for bioaccumulation. Hg in fish and the aquatic environment is also a great problem in the Nordic region of the EU1 (European Union). Hg is classified as a dangerous chemical in the countries of the EU. Hg in the regulation of waste is regarded as a dangerous substance which, when contained in waste, is one of the properties, leading to a classification of waste as hazardous. Estimation of the quantity of Hg in waste within the EU countries is an important task although still incomplete. In this present study, Hg in waste in the EU has been estimated at around 990 metric tonnes (t) (including coal combustion products, landfills, chlor-alkali waste and incinerator slag) for the year 1995, and it is suggested that if complete information was available for the 15 member states, the amount would be 2–4 times larger. During the 1990s there were 45 Hg cell chlorine facilities in the EU and the amount of Hg in chlorine (Cl2) was calculated at 95.2 t based on 14–17 gHg t−1 of Cl2 capacity. The waste from coal-fired power plants in the EU member states contained about 16.5 t of Hg, which was transferred to products for road construction, and other industrial uses or stored in landfills. This Hg can then be exchanged between the atmospheric, aquatic and terrestrial compartments. Hg is occasionally recovered from waste, but this is often discouraged for economic reasons. Recovery units are found, for example, in Germany, France, Austria, and Sweden. The total amount of secondary Hg recovered from waste is not known. Metallic Hg and Hg-bearing waste are exported and imported from the EU member states, except for export from Sweden, which is banned by national legislation. The use of Hg in lamps and batteries is declining, and the Nordic countries, Germany and Austria have stringent regulations on the use of amalgam and Hg thermometers. It is found that 18% of municipal solid waste generated in the EU is burnt in incinerators, in order to decrease the volume. 88 t of Hg enter into the landfills of the EU through waste and residues from waste incineration. Prevention of the generation of hazardous waste containing Hg is one of the most challenging tasks for the EU, with regard to sustainable waste management

Optimized 3D co-registration of ultra-low-field and high-field magnetic resonance images

The prototypes of ultra-low-field (ULF) MRI scanners developed in recent years represent new, innovative, cost-effective and safer systems, which are suitable to be integrated in multi-modal (Magnetoencephalography and MRI) devices. Integrated ULF-MRI and MEG scanners could represent an ideal solution to obtain functional (MEG) and anatomical (ULF MRI) information in the same environment, without errors that may limit source reconstruction accuracy. However, the low resolution and signal-to-noise ratio (SNR) of ULF images, as well as their limited coverage, do not generally allow for the construction of an accurate individual volume conductor model suitable for MEG localization. Thus, for practical usage, a high-field (HF) MRI image is also acquired, and the HF-MRI images are co-registered to the ULF-MRI ones. We address here this issue through an optimized pipeline (SWIM-Sliding WIndow grouping supporting Mutual information). The co-registration is performed by an affine transformation, the parameters of which are estimated using Normalized Mutual Information as the cost function, and Adaptive Simulated Annealing as the minimization algorithm. The sub-voxel resolution of the ULF images is handled by a sliding-window approach applying multiple grouping strategies to down-sample HF MRI to the ULF-MRI resolution. The pipeline has been tested on phantom and real data from different ULF-MRI devices, and comparison with well-known toolboxes for fMRI analysis has been performed. Our pipeline always outperformed the fMRI toolboxes (FSL and SPM). The HF-ULF MRI co-registration obtained by means of our pipeline could lead to an effective integration of ULF MRI with MEG, with the aim of improving localization accuracy, but also to help exploit ULF MRI in tumor imaging

Study of a two steps process for the valorization of PVC-containing wastes

Published online 27 November 2012The presence of organic compounds in wastes, namely polymer based compounds, is considered a potential relevant source of energy. However, the presence of polyvinyl chloride (PVC) in their composition, causes recycling problems when a thermal process is considered for the wastes treatment [1] preventing its use on processes which the main goal is the energy recovery (Zevenhoven et al. in Fuel 81:507–510, 2002; Kim in Waste Manag 21:609–616, 2001). A possible solution should consider a first step for chlorine removal, through a pyrolysis process previously to a subsequent thermal treatment, for energetic valorization. The present work assesses a possible process for treating PVC-containing wastes in an environmentally friendly way. It is based on the effective de-chlorination of PVC-containing wastes through a pyrolysis process at low temperature before the carbonaceous residue (chlorine free fraction) being subjected to a subsequent thermal treatment for energetic valorization with the production of a synthesis gas (syngas). In the end of the process concentrated hydrochloric acid or other chlorine solutions and a syngas, with high energetic potential are obtained. The synthesis gas produced can be used in turbines or gas engines, replacing the gases obtained from fossil non-renewable resources. The validation of the proposed treatment of PVC-containing wastes in pilot scale has also been performed

Kinetic and economic analysis of reactive capture of dilute carbon dioxide with Grignard reagents

Carbon Dioxide Utilisation (CDU) processes face significant challenges, especially in the energetic cost of carbon capture from flue gas and the uphill energy gradient for CO2 reduction. Both of these stumbling blocks can be addressed by using alkaline earth metal compounds, such as Grignard reagents, as sacrificial capture agents. We have investigated the performance of these reagents in their ability to both capture and activate CO2 directly from dried flue gas (essentially avoiding the costly capture process entirely) at room temperature and ambient pressures with high yield and selectivity. Naturally, to make the process sustainable, these reagents must then be recycled and regenerated. This would potentially be carried out using existing industrial processes and renewable electricity. This offers the possibility of creating a closed loop system whereby alcohols and certain hydrocarbons may be carboxylated with CO2 and renewable electricity to create higher-value products containing captured carbon. A preliminary Techno-Economic Analysis (TEA) of an example looped process has been carried out to identify the electrical and raw material supply demands and hence determine production costs. These have compared broadly favourably with existing market values

Discovery of a small arterivirus gene that overlaps the GP5 coding sequence and is important for virus production

The arterivirus family (order Nidovirales) of single-stranded, positive-sense RNA viruses includes porcine respiratory and reproductive syndrome virus and equine arteritis virus (EAV). Their replicative enzymes are translated from their genomic RNA, while their seven structural proteins are encoded by a set of small, partially overlapping genes in the genomic 3′-proximal region. The latter are expressed via synthesis of a set of subgenomic mRNAs that, in general, are functionally monocistronic (except for a bicistronic mRNA encoding the E and GP2 proteins). ORF5, which encodes the major glycoprotein GP5, has been used extensively for phylogenetic analyses. However, an in-depth computational analysis now reveals the arterivirus-wide conservation of an additional AUG-initiated ORF, here termed ORF5a, that overlaps the 5′ end of ORF5. The pattern of substitutions across sequence alignments indicated that ORF5a is subject to functional constraints at the amino acid level, while an analysis of substitutions at synonymous sites in ORF5 revealed a greatly reduced frequency of substitution in the portion of ORF5 that is overlapped by ORF5a. The 43–64 aa ORF5a protein and GP5 are probably expressed from the same subgenomic mRNA, via a translation initiation mechanism involving leaky ribosomal scanning. Inactivation of ORF5a expression by reverse genetics yielded a severely crippled EAV mutant, which displayed lower titres and a tiny plaque phenotype. These defects, which could be partially complemented in ORF5a-expressing cells, indicate that the novel protein, which may be the eighth structural protein of arteriviruses, is expressed and important for arterivirus infection

Discovery of a small arterivirus gene that overlaps the GP5 coding sequence and is important for virus production

The arterivirus family (order Nidovirales) of single-stranded, positive-sense RNA viruses includes porcine respiratory and reproductive syndrome virus and equine arteritis virus (EAV). Their replicative enzymes are translated from their genomic RNA, while their seven structural proteins are encoded by a set of small, partially overlapping genes in the genomic 3′-proximal region. The latter are expressed via synthesis of a set of subgenomic mRNAs that, in general, are functionally monocistronic (except for a bicistronic mRNA encoding the E and GP2 proteins). ORF5, which encodes the major glycoprotein GP5, has been used extensively for phylogenetic analyses. However, an in-depth computational analysis now reveals the arterivirus-wide conservation of an additional AUG-initiated ORF, here termed ORF5a, that overlaps the 5′ end of ORF5. The pattern of substitutions across sequence alignments indicated that ORF5a is subject to functional constraints at the amino acid level, while an analysis of substitutions at synonymous sites in ORF5 revealed a greatly reduced frequency of substitution in the portion of ORF5 that is overlapped by ORF5a. The 43–64 aa ORF5a protein and GP5 are probably expressed from the same subgenomic mRNA, via a translation initiation mechanism involving leaky ribosomal scanning. Inactivation of ORF5a expression by reverse genetics yielded a severely crippled EAV mutant, which displayed lower titres and a tiny plaque phenotype. These defects, which could be partially complemented in ORF5a-expressing cells, indicate that the novel protein, which may be the eighth structural protein of arteriviruses, is expressed and important for arterivirus infection

Ash agglomeration and deposition during combustion of poultry litter in a bubbling fluidized-bed combustor

peer-reviewedn this study, we have characterized the ash resulting from fluidized bed combustion of poultry litter as being dominated by a coarse fraction of crystalline ash composed of alkali-Ca-phosphates and a fine fraction of particulate K2SO4 and KCl. Bed agglomeration was found to be coating-induced with two distinct layers present. The inner layer (0.05–0.09 mm thick) was formed due to the reaction of gaseous potassium with the sand (SiO2) surface forming K-silicates with low melting points. Further chemical reaction on the surface of the bed material strengthened the coating forming a molten glassy phase. The outer layer was composed of loosely bound, fine particulate ash originating from the char. Thermodynamic equilibrium calculations showed slag formation in the combustion zone is highly temperature-dependent, with slag formation predicted to increase from 1.8 kg at 600 °C to 7.35 kg at 1000 °C per hour of operation (5.21 kg of ash). Of this slag phase, SiO2 and K2O were the dominant phases, accounting for almost 95%, highlighting the role of K-silicates in initiating bed agglomeration. The remaining 5% was predicted to consist mainly of Al2O3, K2SO4, and Na2O. Deposition downstream in the low-temperature regions was found to occur mostly through the vaporization–condensation mechanism, with equilibrium decreasing significantly with decreasing temperatures. The dominant alkali chloride-containing gas predicted to form in the combustion zone was KCl, which corresponds with the high KCl content in the fine baghouse ash