117 research outputs found

    Gasification of solid waste — potential and application of co-current moving bed gasifiers

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    A review is given of gasification processes for solid fuels with special emphasis on waste gasification. Although the co-current moving bed gasifier has not been under consideration for a long time, it offers interesting possibilities for waste gasification. Some operational data are given.\ud Two potential applications are discussed—gasification of agricultural waste (maize cobs) in the rural areas of Tanzania and municipal waste gasification

    Die Erzeugung teerfreien Gases in einem Gleichstrom-Festbett-Vergaser

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    This paper discusses the fundamentals, mechanical engineering and commercialisation of co-current moving bed gasifiers. The process engineering aspect stresses that gasifiers can be designed to obtain tar-free product gas. Based on the fuel properties, the fire hearth has to be adjusted, with an annular throat concept applied in the case of larger capacities and fine fuel. Models are presented for maximum capacity calculations of gasifiers with respect to tar production and for reduction zone design. From a mechanical engineering aspect fuel handling, materials selection, ash removal, gas treatment and utilization as well as safety risks are discussed. The present state of gasifier commercialization is given. The economic evaluation leads to the conclusion that gasification is a viable option for direct heating and co-generation

    Combining Photodegradation in a Liquid-Core-Waveguide Cell with Multiple-Heart-Cut Two-Dimensional Liquid Chromatography

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    Photodegradation greatly affects everyday life. It poses challenges when food deteriorates or when objects of cultural heritage fade, but it can also create opportunities applied in advanced oxidation processes in water purification. Studying photodegradation, however, can be difficult because of the time needed for degradation, the inaccessibility of pure compounds, and the need to handle samples manually. A novel light-exposure cell, based on liquid-core-waveguide (LCW) technology, was embedded in a multiple-heart-cut two-dimensional liquid chromatography system by coupling the LCW cell to the multiple-heart-cut valve. The sample was flushed from the heart-cut loops into the cell by an isocratic pump. Samples were then irradiated using different time intervals and subsequently transferred by the same isocratic pump to a second-dimension sample loop. The mixture containing the transformation products was then subjected to the second-dimension separation. In the current setup, about 30-40% of the selected fraction was transferred. Multiple degradation products could be monitored. Degradation was found to be faster when a smaller sample amount was introduced (0.3 μg as compared to 1.5 μg). The system was tested with three applications, that is, fuchsin, a 19th-century synthetic organic colorant, annatto, a lipophilic food dye, and vitamin B complex

    Low tidal volume ventilation ameliorates left ventricular dysfunction in mechanically ventilated rats following LPS-induced lung injury

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    Background: High tidal volume ventilation has shown to cause ventilator-induced lung injury (VILI), possibly contributing to concomitant extrapulmonary organ dysfunction. The present study examined whether left ventricular (LV) function is dependent on tidal volume size and whether this effect is augmented during lipopolysaccharide(LPS)-induced lung injury. Methods: Twenty male Wistar rats were sedated, paralyzed and then randomized in four groups receiving mechanical ventilation with tidal volumes of 6 ml/kg or 19 ml/kg with or without intrapulmonary administration of LPS. A conductance catheter was placed in the left ventricle to generate pressure-volume loops, which were also obtained within a few seconds of vena cava occlusion to obtain relatively load-independent LV systolic and diastolic function parameters. The end-systolic elastance / effective arterial elastance (Ees/Ea) ratio was used as the primary parameter of LV systolic function with the end-diastolic elastance (Eed) as primary LV diastolic function. Results: Ees/Ea decreased over time in rats receiving LPS (p = 0.045) and high tidal volume ventilation (p = 0.007), with a lower Ees/Ea in the rats with high tidal volume ventilation plus LPS compared to the other groups (p < 0.001). Eed increased over time in all groups except for the rats receiving low tidal volume ventilation without LPS (p = 0.223). A significant interaction (p < 0.001) was found between tidal ventilation and LPS for Ees/Ea and Eed, and all rats receiving high tidal volume ventilation plus LPS died before the end of the experiment. Conclusions: Low tidal volume ventilation ameliorated LV systolic and diastolic dysfunction while preventing death following LPS-induced lung injury in mechanically ventilated rats. Our data advocates the use of low tidal volumes, not only to avoid VILI, but to avert ventilator-induced myocardial dysfunction as well

    Soluble receptor for advanced glycation end products as an indicator of pulmonary vascular injury after cardiac surgery

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    Background: Cardiac surgery is frequently complicated by an acute vascular lung injury and this may be mediated, at least in part, by the (soluble) receptor for advanced glycation end products (sRAGE).Methods: In two university hospital intensive care units, circulating sRAGE was measured together with the 68Gallium-transferrin pulmonary leak index (PLI), a measure of pulmonary vascular permeabiliy, in 60 consecutive cardiac surgery patients stratified by the amount of blood transfusion, within 3 hours of admission to the intensive care.Results: Cardiac surgery resulted in elevated plasma sRAGE levels compared to baseline (315 ± 181 vs 110 ± 55 pg/ml, P = 0.001). In 37 patients the PLI was elevated 50% above normal. The PLI correlated with sRAGE (r2 = 0.11, P = 0.018). Plasma sRAGE discriminated well between those with an elevated PLI and those with a normal PLI (area under the operator curve 0.75; P = 0.035; 95% CI 0.55-0.95), with 91% sensitivity but low specificity of 36% at a cutoff value of 200 pg/mL
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