The boiler efficiency of a Lignite fuelled power station can be significantly affected by the distribution of the coal within the boiler furnace. The mill-duct systems are designed to allow ...sufficient resident time for the raw Lignite to dry. The raw Lignite, which contains approximately 66% water, is conveyed by post combustion hot off-take gases and delivered to the furnace with an appropriate distribution to ensure when mixed with sufficient oxygen, complete combustion occurs. The mill-duct systems for a lignite fuelled boiler are generally very complex and as such, are not yet fully understood. The distributions of the coal and gas mixture within these complicated mill ducts have been investigated experimentally and numerically to better understand the flow patterns. Isokinetic sampling of the gas and coal was undertaken within the lower, intermediate and upper legs of a mill-duct system downstream of the grinding mill under standard operating load at the Loy Yang B power station in the Latrobe Valley, Australia. CFD modelling using an Eulerian/Lagrangian approach, due to the low solids-to-gas ratio, was used to achieve good agreement with the experimental data. The gas–coal mixture must travel through a series of bends before entering the furnace and a bias of coal flow toward the outer wall of the upper and lower legs was noted downstream of the bend at the trifurcation for the mill-duct legs. The slightly different geometry configuration of the intermediate resulted in a more homogenous coal and gas flow but a significantly lower coal loading than the upper and lower legs.
The distributions of the coal and gas mixture within complicated mill ducts have been investigated experimentally and numerically to better understand the flow patterns. Isokinetic sampling of the gas and coal was undertaken within the lower, intermediate and upper legs of a mill-duct system downstream of the grinding mill under standard operating load at the Loy Yang B power station in the Latrobe Valley, Australia. CFD modelling using an Eulerian/Lagrangian approach, due to the low solids-to-gas ratio, was used to achieve good agreement with the experimental data.
Normalised PF mass flow profiles in one of the mill-duct legs. Display omitted
►Coal flow were predicted and measured for a power station supply duct. ►Coal distribution and coal velocity showed greater unsteadiness compared to gas. ►Coal flow was biased by geometric configurations leading to uneven distribution.
There are thousands of published methods for profiling metabolites with liquid chromatography/mass spectrometry (LC/MS). While many have been evaluated and optimized for a small number of select ...metabolites, very few have been assessed on the basis of global metabolite coverage. Thus, when performing untargeted metabolomics, researchers often question which combination of extraction techniques, chromatographic separations, and mass spectrometers is best for global profiling. Method comparisons are complicated because thousands of LC/MS signals (so-called features) in a typical untargeted metabolomic experiment cannot be readily identified with current resources. It is therefore challenging to distinguish methods that increase signal number due to improved metabolite coverage from methods that increase signal number due to contamination and artifacts. Here, we present the credentialing protocol to remove the latter from untargeted metabolomic datasets without having to identify metabolite structures. This protocol can be used to compare or optimize methods pertaining to any step of the untargeted metabolomic workflow (e.g., extraction, chromatography, mass spectrometer, informatic software, etc.).
Detailed analyses of smoke movement from a burning vehicle in a road tunnel have been carried out for the westbound Melbourne City Link tunnel. The time-averaged equations for velocity, pressure, ...temperature, and mass fraction of emissions were solved for transient condition using the CFD software FLUENT 6.0. For the analysis, a burning bus was assumed to release an equivalent energy of burning 500 l of diesel in 6 min, with vehicles upstream of the fire at a standstill. On the other hand, the vehicles downstream of the fire had enough time to escape from the tunnel through the exit portal. Due to the action of jet fans, most of the smoke was pushed downstream of the fire. The smoke had also dispersed about 55 m upstream of the fire, putting the passengers in this region at great risk. The emissions released from the vehicles in the jam, with their engines running, also posed a threat to human health. Within 8 min after the fire had started, the mass concentrations of O
2, CO
2 and CO were in the ranges of 0.12–0.15, 0.08–0.11 and 0.0006–0.0014, respectively. Therefore, quick evacuation of the passengers is essential in the event of a fire in the tunnel.
After heavy rainfall, sewer overflow spills to receiving water bodies cause serious concern for the environment, aesthetics and public health. To overcome these problems this study investigated a new ...self-cleansing sewer overflow screening device. The device has a sewer overflow chamber, a rectangular tank and a slotted ogee weir to capture the gross pollutants. To design an efficient screening device a numerical computational fluid dynamic (CFD) model was used. A plausibility check of the CFD model was done using a one-dimensional analytical model. Results showed that an inlet parallel to the weir ensured better self-cleansing than an inlet perpendicular to the weir. Perforations should be at the bottom of the weir to get increased velocity and shear stress to create a favourable self-cleaning effect of the screening device. Increasing inlet length from 0.3 to 1.5 m reduced wave reflection up to 10%, which increased flow uniformity downstream and improved self-cleansing effect. The orientation of the ogee weir with the rectangular tank was found most uniform with a 1:3 (horizontal:vertical) slope. These results will help to maximise functional efficiency of the new sewer overflow screening device. Otherwise it would be too expensive to alter after installation and at times difficult to customise accordingly to existing urban drainage systems.
A comprehensive 3D CFD model has been developed for analyzing thermal conversion of woody biomass fuel in a large reciprocating grate boiler under air/oxy-fuel condition. A number of sub-models ...representing solid conversion processes such as drying, devolatilisation and char combustion, gas phase flow and chemical reactions, solid and gas phase interaction through heat and mass transfer and bed movement is included in the model by user defined subroutines. The model has been validated by simulating a moving grate furnace from literature and comparing results with this reference experimental study. In this work, wet woody biomass fuel combustion is investigated under different oxy-fuel condition. Three different oxy-fuel cases have been investigated with 25% O2 (OF 25), 27% O2 (OF 27) and 30% O2 (OF 30) concentration by volume in the feed oxidizer gas with CO2 as recycled flue gas. Furnace operating condition is varied by changing air mass flow and inlet oxidizer gas composition, but all other operating conditions and furnace thermal load were kept constant. The effect of O2/recycled flue gas (CO2) ratios on flame temperature distribution, species concentration, char burnout and fuel consumption have been studied in detail and substantial differences were noticed comparing with the air-fired case. The numerical prediction showed that, gas temperature profile OF 25 case is closer to the referenced air fired combustion. The gas flame temperature has increased with O2 concentration rise, reaching maximum temperature at OF 30 case. CO2 concentration was increased to almost three times than air fired case due to use of CO2 in the feed gas. Increased CO2 concentration in the furnace has augmented char combustion rate and fuel consumption. Maximum fuel consumption was observed for OF 30 case where the fuel bed distribution over the grate was found minimum. Therefore, biomass bed combustion under oxy-fuel condition can provide better flame temperature and char burning to improve combustion condition.
•A 3D CFD model is developed for biomass combustion in moving grate furnace.•Several sub-models of the combustion process are incorporated.•The model is validated by simulating an experimental furnace.•Biomass thermal conversion is studied under air and oxy-fuel conditions.•Combustion performance under oxy-fuel condition is analysed.
Existing hydrophilic interaction liquid chromatography (HILIC) methods, considered individually, each exhibit poor chromatographic performance for a substantial fraction of polar metabolites. In ...addition to limiting metabolome coverage, such deficiencies also complicate automated data processing. Here we show that some of these analytical challenges can be addressed for the ZIC-pHILIC, a zwitterionic stationary phase commonly used in metabolomics, with the addition of trace levels of phosphate. Specifically, micromolar phosphate extended metabolome coverage by hundreds of credentialed features, improved peak shapes, and reduced peak-detection errors during informatic processing. Although the addition of high levels of phosphate (millimolar) as a HILIC mobile phase buffer has been explored previously, such concentrations interfere with mass spectrometric (MS) detection. We show that using phosphate as a trace additive at micromolar concentrations improves analysis by electrospray MS, increasing signal for a diverse set of polar standards. Given the small amount of phosphate needed, comparable chromatographic improvements were also achieved by direct addition of phosphate to the sample during reconstitution. Our results suggest that defects in ZIC-pHILIC performance are predominantly driven by electrostatic interactions, which can be modulated by phosphate. These findings constitute both a methodological improvement for untargeted metabolomics and an advance in our understanding of the mechanisms limiting HILIC coverage.
Abstract
Concentrations of heavy metals in gallstones samples gathered from different hospital were estimated via laser induced breakdown spectroscopy (LIBS (.Quantitative and qualitative analysis of ...the gallstone samples were achieved by using the locally developed LIBS set up equipped with Nd: YAG laser (Q-switched) at 1064 nm, pulse duration 9 ns and pulse energy 300 mJ. Quantitative analysis was performed for Cr, Cd, Zn, Pb, Cu and As based on calibration curve constructed from the correlation between the intensity of the LIBS emission lines and the concentration of each element measured by AAS. It was noticed that the percentage of copper, zinc, and manganese was higher in pigment samples higher than in mixed samples, and that it was not present in the cholesterol samples. However, chromium and cadmium elements were present in a high percentage in cholesterol samples and higher than other types of gallstones. The most important conclusion was that heavy elements such as Pb and As were present in the samples of smoking patients. The relative errors for all samples were in the range of (1.5-7.8) %.
The cell-intrinsic nature of tumor metabolism has become increasingly well characterized. The impact that tumors have on systemic metabolism, however, has received less attention. Here, we used adult ...zebrafish harboring BRAFV600E-driven melanoma to study the effect of cancer on distant tissues. By applying metabolomics and isotope tracing, we found that melanoma consume ~15 times more glucose than other tissues measured. Despite this burden, circulating glucose levels were maintained in disease animals by a tumor-liver alanine cycle. Excretion of glucose-derived alanine from tumors provided a source of carbon for hepatic gluconeogenesis and allowed tumors to remove excess nitrogen from branched-chain amino acid catabolism, which we found to be activated in zebrafish and human melanoma. Pharmacological inhibition of the tumor-liver alanine cycle in zebrafish reduced tumor burden. Our findings underscore the significance of metabolic crosstalk between tumors and distant tissues and establish the adult zebrafish as an attractive model to study such processes.
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•Adult zebrafish are well suited for steady-state labeling and metabolomics•Branched-chain amino acid catabolism by melanoma contributes to alanine excretion•Glucose-derived alanine excreted from the tumor is used for hepatic gluconeogenesis•Pharmacological inhibition of the tumor-liver alanine cycle reduces tumor burden
Using a workflow they established for isotope tracing in adult zebrafish, Naser et al. provide evidence that non-malignant tissues alter their metabolism to support tumor growth. They demonstrate that glucose-derived alanine is excreted from melanoma and transferred to the liver for gluconeogenesis. Pharmacologically impairing this metabolite exchange decreases tumor burden.
The research aims to choose the paths of urban expansion byadopting a correct scientific approach that enhances themethodology of spatial analysis of the most appropriate sitesby studying indicators ...that affect the city, and since thehierarchical analysis method is a scientific method, i.e. the twowaycomparison process, the comparison of couples is the onewho reaches the relative weights of factors or Indicators andevaluation. Therefore, spatial decision-making usuallyincludes many criteria that reflect the opinions and decisionsof decision-makers, experts, interested parties andstakeholders to determine the paths of urban expansion, andbecause of these multiple opinions and decisions, all thesematters must be resolved through the adoption of a strategy ofdirect integration into the environment of information systemsprograms. The geographical representation of the results of thehierarchical analysis, which was based on the weights of allfactors, i.e. the main and sub-indicators obtained from theExpert Choice program, which worked on the integration andintegration of multi-criteria capabilities by creating anintegrated integrated unit, which proved to provide andprovide practical and scientific solutions to decision makers inthe least possible time and cost. Effort as well as its ability andcompetence to provide technical support to planning decisionmakers. Through what we mentioned in the study of assessingthe spatial suitability of urban expansion, we obtained theresults of the most appropriate, most and least appropriate forthe areas of determining the paths of urban expansion in thecity of Kirkuk.
Gas vortices generated in the freeboard of a bubbling fluidised bed have become the centre of increasingly more research due to the advances in experimental technology. The behaviour of gas flow in ...the freeboard of a bubbling fluidised bed is of interest for applications such as the gasification of coal where reactions of gas mixtures, as well as gas–particle heat and mass transfer take place. Knowledge of the hydrodynamics of the gas within the freeboard can be hard to characterise, especially the detailed behaviour of gases escaping from bubbles that erupt at the bed surface. In the present study, experiments were conducted on a rectangular three-dimensional gas–solid fluidised bed. The experiments used a particle imaging velocimetry (PIV) measurement technique to visualise and measure the gas flow within the freeboard after a single bubble eruption. A computational study was carried out using Eulerian–Eulerian, kinetic theory of granular flow approach with a quasi-static flow model and with LES used to account for gas turbulence. Results from a three dimensional simulation of the experimental fluidised bed were compared with experimental velocity profiles of gas flow in the freeboard of the gas–solid fluidised bed after a bubble eruption. The CFD simulations showed a qualitative agreement with the formation of the gas vortices as the bubble erupted. Consistent with experimental findings the CFD simulations showed the generation of a pair of vortices. However, the simulations were unable to demonstrate downward flow at the centre of the freeboard due to particles in free fall after a bubble eruption event was observed in the experiments. Velocity profiles from the CFD data are in reasonably good agreement with the characteristic trends observed in the experiments, whereas the CFD model was able to predict the gas vortices phenomena and the velocity magnitudes were over-predicted.
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