To systematically investigate high-temperature corrosion of superheaters in biomass combined heat and power (CHP) plants, a long-term test run (5 months) with online corrosion probes was performed in an Austrian CHP plant (28 MW_NCV; steam parameters: 32 t/h at 480 °C and 63 bar) firing chemically untreated wood chips. Two corrosion probes were applied in parallel in the radiative section of the boiler at average flue gas temperatures of 880 and 780 °C using the steel 13CrMo4-5 for the measurements. Corrosion rates were determined for surface temperatures between 400 and 560 °C. The results show generally moderate corrosion rates and a clear dependence upon the flue gas temperatures and the surface temperatures of the corrosion probes, but no influence of the flue gas velocity has been observed. The data are to be used to create corrosion diagrams to determine maximum steam temperatures for superheaters in future plants, which are justifiable regarding the corrosion rate. Dedicated measurements were performed at the plant during the long-term corrosion probe test run to gain insight into the chemical environment of the corrosion probes. From fuel analyses, the molar 2S/Cl ratio was calculated with an average of 6.0, which indicates a low risk for high-temperature corrosion. Chemical analyses of aerosols sampled at the positions of the corrosion probes showed that no chlorine is present in condensed form at the positions investigated. Deposit probe measurements performed at the same positions and analyses of the deposits also showed only small amounts of chlorine in the deposits, mainly found at the leeward position of the probes. Subsequent to the test run, the corrosion probes have been investigated by means of scanning electron microscopy/energy-dispersive X-ray spectroscopy analyses. The results confirmed the deposit probe measurements and showed only minor Cl concentrations in the deposits and no Cl at the corrosion front. Because, in the case of Cl-catalyzed active oxidation, a layer of Cl is known to be found at the corrosion front, this mechanism is assumed to be not of relevance in the case at hand. Instead, elevated S concentrations were detected at the corrosion front, but the corrosion mechanism has not yet been clarified.

Der vorliegende Beitrag analysiert die historische Entwicklung der Bioenergienutzung sowie deren aktuellen Stellenwert in der Energieversorgung Österreichs. In weiterer Folge werden auf Basis von Prognosen die zukünftige Entwicklung der Bioenergienutzung in Österreich sowie die damit einhergehenden Herausforderungen umrissen. Aktuelle Leuchtturmprojekte im Bioenergiesektor und Aspekte aus der österreichischen Bioenergieforschung ergänzen den Beitrag.

Management of municipal and commercial waste in Austria frequently involves mechanical-biological treatment (MBT) followed by incineration. A middle-caloric MBT output stream (lower heating value (LHV) = 9.90 MJ/kg WW, particle size = 20-80 mm) with a high proportion of inert material like stones, bricks, and metals (40.5 %m) is currently incinerated. Under favorable market conditions, it could be economically advantageous to split off a low-caloric heavy fraction (HF) that can be landfilled and to incinerate only the remaining, lighter fraction (LF) with a higher heating value. This study analyzes the specific global-warming potential (100-year GWP per tonne of input waste) of such an additional separation step and of the subsequent treatment processes. Four treatment alternatives were considered: a reference scenario without separation and three separation scenarios – a near-infrared (NIR) sensor-based scenario, an X-ray-transmission (XRT) sensor-based scenario, and a mechanical separation scenario using a diagonal sifter (DS). To calculate the specific GWP, the analysis applied techniques from life-cycle assessment (LCA). Primary data were obtained from pilot-scale and full-scale separation experiments, and from equipment manufacturers. Commercial databases provided secondary data. The results consist of separate LCA models for each scenario, including credits for fossil fuels replaced by LF incineration and HF landfill gas utilization. When only direct separation-related emissions are considered, the DS separation has by far the lowest specific GWP, followed by NIR-based separation, and by XRT-based separation. Overall specific GWP is strongly influenced by the choice of separation technology. It is lowest for the XRT scenario, followed closely by the reference scenario, while the DS and NIR scenarios show considerably higher results. Results are dominated by the net emissions from LF incineration. While incineration emissions are largely compensated by credits from replaced fossil fuels, credits for landfill gas utilization are much smaller than direct landfilling emissions. The ranking of the separation scenarios is largely determined by three waste stream characteristics: the ratio of biogenic to fossil carbon content and the LHV in the LF, and the degradable biogenic carbon content in the HF. Changes in important modeling assumptions leave the ranking between scenarios unchanged. It can be concluded that – given the right choice of
separation technology – a small positive effect of sorting on the overall specific GWP is feasible. This
work demonstrates that global warming effects of waste treatment decisions can be estimated and
considered early in the planning stage of treatment system design.

This publication deals with the characterisation of Jatropha curcas seeds and the oil obtained hereof. The analyzed seeds have been harvested from hedges and plantations in the regions of Teriya Bugu and Bla in Mali in the years 2009 and 2010. The oil is obtained through solvent extraction. Parameters analyzed are those which are relevant for processing of the oil into fatty acid methyl ester (FAME, biodiesel), and include acid value, fatty acid profile and contents of S, P, K, Na, Ca and Mg. All oil samples are suitable for processing into biodiesel, but some of them require pre-treatment because of high contents of free fatty acids and phosphorous. The margin of deviation of acid value and element contents throughout the oil samples depends on the way of cultivation, harvest and storage of the Jatropha curcas plants and seeds. Despite high acid values, all oil samples show high oxidation stability. © 2012 Elsevier Ltd.

Der vorliegende Beitrag analysiert die Auswirkungen unterschiedlicher Brennstoffversorgungsszenarios im Calcinator des Zementherstellungsprozesses auf die emittierten CO2-Emissionen. In weiterer Folge werden die Grenzvermeidungskosten für CO2 im Vergleich zum Referenzszenario (100 % PetCoke) berechnet und dargestellt. Als alternative Brennstoffe werden auf Basis von Betriebserfahrungen sowie großtechnischer Versuche die alternativen Brennstoffe hochkalorischer Fluff (Standardszenario) sowie Schilf (Szenario A) und biogen angereicherter Ersatzbrennstoff (Szenario B) und vergleichend dazu in einer Literaturbasierten Analyse getrockneter Klärschlamm (Szenario C) betrachtet. Um die Auswirkung sich ändernder Marktbedingungen auf die Grenzvermeidungskosten abzubilden erfolgt eine Sensitivitätsanalyse hinsichtlich der Brennstoffgestehungskosten für die alternativen Brennstoffe sowie drei unterschiedliche Preisniveaus für Emissionsrechte und Brennstoffgestehungskosten des Referenzbrennstoffes PetCoke.

The aim of the current study was to investigate the feasibility of membrane contactors for continuous ammonia (NH₃-N) removal in an anaerobic digestion process and to counteract ammonia inhibition. Two laboratory anaerobic digesters were fed slaughterhouse wastes with ammonium (NH₄⁺) concentrations ranging from 6 to 7.4 g/L. One reactor was used as reference reactor without any ammonia removal. In the second reactor, a hollow fiber membrane contactor module was used for continuous ammonia removal. The hollow fiber membranes were directly submerged into the digestate of the anaerobic reactor. Sulfuric acid was circulated in the lumen as an adsorbent solution. Using this set up, the NH₄⁺-N concentration in the membrane reactor was significantly reduced. Moreover the extraction of ammonia lowered the pH by 0.2 units. In combination that led to a lowering of the free NH₃-N concentration by about 70%. Ammonia inhibition in the reference reactor was observed when the concentration exceeded 6 g/L NH₄⁺-N or 1-1.2 g/L NH₃-N. In contrast, in the membrane reactor the volatile fatty acid concentration, an indicator for process stability, was much lower and a higher gas yield and better degradation was observed. The chosen approach offers an appealing technology to remove ammonia directly from media having high concentrations of solids and it can help to improve process efficiency in anaerobic digestion of ammonia rich substrates. © 2012 Elsevier Ltd.