Industrial rotating kiln simulation

University of Technology, Sydney. Faculty of Science.A new industrial process is being developed to allow the commercial recovery of oil from oil shales. As part of this process, a rotating kiln is used to pyrolyse the organic component of the oil shales. The configuration and application of this rotating kiln is unique and hence previous rotating kiln models cannot be used to predict the solid behaviour in the current processor. It is the aim of this work to develop mathematical models which allow the prediction of mixing, segregation and heat transfer in industrial rotating kilns, especially with respect to the new rotating kiln technology trialed in the oil shale industry. Experiments were developed to observe and measure the mixing and segregation behaviour of solids in rotating drums. These experiments used image analysis and provided quantitative results. Further experiments were carried out to allow suitable scaling parameters to be developed. All the mixing experiments followed a constant mixing rate until the bed became fully mixed. The mixing rate and the final amount of mixing depended on the rotational velocity, the drum loading, the particle size and the material ratio. The segregation dynamics occurred too fast to be measured. However the final segregated state was measured and depended on the rotational velocity and the differences in particle sizes. Scaling parameters were developed that related the mixing and segregation results to the operational variables of the rotating kiln. Mathematical models were derived for the mixing and segregation of solids in a rotating kiln and these models included the developed scaling parameters so that these models would be useful for the prediction of the solid behaviour in industrial rotating kilns. The mathematical models were applied to independent experiments and it was found that they predicted the mixing and segregation to within the experimental error, even for different sized drums indicating that the developed scaling parameters were suitable. A computational simulation of the industrial rotating kiln processor was developed by combining the mathematical models of the mixing and segregation with heat transfer modelling applicable to this industrial rotating kiln. A case study was completed to study the behaviour of the industrial rotating kiln by changing operational variables, such as the rotational speed and the particle size. The developed simulation can be used to predict the dynamic behaviour of the rotating kiln used in the emerging oil from oil shale industry. This simulation can assist in further commercialisation of this new industrial process

Global diversity and antimicrobial resistance of typhoid fever pathogens: Insights from a meta-analysis of 13,000 Salmonella Typhi genomes

Background: The Global Typhoid Genomics Consortium was established to bring together the typhoid research community to aggregate and analyse Salmonella enterica serovar Typhi (Typhi) genomic data to inform public health action. This analysis, which marks 22 years since the publication of the first Typhi genome, represents the largest Typhi genome sequence collection to date (n=13,000). Methods: This is a meta-analysis of global genotype and antimicrobial resistance (AMR) determinants extracted from previously sequenced genome data and analysed using consistent methods implemented in open analysis platforms GenoTyphi and Pathogenwatch. Results: Compared with previous global snapshots, the data highlight that genotype 4.3.1 (H58) has not spread beyond Asia and Eastern/Southern Africa; in other regions, distinct genotypes dominate and have independently evolved AMR. Data gaps remain in many parts of the world, and we show the potential of travel-associated sequences to provide informal ‘sentinel’ surveillance for such locations. The data indicate that ciprofloxacin non-susceptibility (>1 resistance determinant) is widespread across geographies and genotypes, with high-level ciprofloxacin resistance (=3 determinants) reaching 20% prevalence in South Asia. Extensively drug-resistant (XDR) typhoid has becomedominant in Pakistan (70% in 2020) but has not yet become established elsewhere. Ceftriaxone resistance has emerged in eight non-XDR genotypes, including a ciprofloxacin-resistant lineage (4.3.1.2.1) in India. Azithromycin resistance mutations were detected at low prevalence in South Asia, including in two common ciprofloxacin-resistant genotypes. Conclusions: The consortium’s aim is to encourage continued data sharing and collaboration to monitor the emergence and global spread of AMR Typhi, and to inform decision-making around the introduction of typhoid conjugate vaccines (TCVs) and other prevention and control strategies