Publications Search Results

Now showing 1 - 10 of 32
  • Publication
    Development of a New Sensor Module for an Enhanced Fuel Flexible Operation of Biomass Boilers
    The heterogeneity of biogenic fuels, and especially biogenic residues with regard to water and ash content, particle size and particle size distribution is challenging for biomass combustion, and limits fuel flexibility. Online fuel characterization as a part of process control could help too ptimize combustion processes, increase fuel flexibility and reduce emissions. In this research article, a concept for a new sensor module is presented and first tests are displayed to show its feasibility. The concept is based on the principle of hot air convective drying. The idea is to pass warm air with 90 °C through a bulk of fuel like wood chips and measure different characteristics such as moisture, temperatures and pressure drop over the bulk material as a function over time. These functions are the basis to draw conclusions and estimate relevant fuel properties. To achieve this goal, a test rig with a volume of 0.038 m3 was set up in the laboratory and a series of tests was performed with different fuels (wood chips, saw dust, wood pellets, residues from forestry, corncobs and biochar). Further tests were carried out with conditioned fuels with defined water and fines contents. The experiments show that characteristic functions arise over time. The central task for the future will be to assign these functions to specific fuel characteristics. Based on the data, the concept for a software for an automated, data‐based fuel detection system was designed.
  • Publication
    Full assessment of Sida (Sida hermaphrodita) biomass as a solid fuel
    ( 2020)
    Jablonowski, Nicolai David
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    Kollmann, Tobias
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    Dohrn, M.
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    Müller, M.
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    Nabel, M.
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    Zapp, P.
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    Schonhoff, A.
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    Schrey, S.D.
    Due to an increased awareness of climate change and limited fossil resources, the demand of alternative energy carriers such as biomass has risen significantly during the past years. This development is supported by the idea of a transition to a bio-based economy reducing fossil based carbon dioxide emissions. Based on this trend, biomass for energy is expected to be used in the EU mainly for heating until the end of the decade. The perennial herbaceous mallow plant Sida hermaphrodita (L.) Rusby (""Sida"") has high potential as an alternative biomass plant for energy purposes. Different density cultivation scenarios of Sida accounting for 1, 2, or 4plants m-2 resulted in a total biomass yield of 21, 28, and 34 tons dry matter ha-1, respectively, over a three-year period at agricultural conditions, while the overall investment costs almost doubled from 2 to 4 plants m-2. Subsequently, Sida biomass was used as SI) chips, SII) pellets, and SIII) briquettes for combustion studies at pilot plant scale. Pellets outcompeted chips and briquettes by showing low CO emission of 40 mg Nm-3, good burnout and low slagging behavior, however with elevated NOx and SO2 levels. In contrast, combustion of chips and briquettes displayed high CO emissions of >1300 mg Nm-3, while SO2 values were below 100mg Nm-3. Contents of HCl in the flue gas ranged between 32 and 52 mg Nm-3 for all Sida fuels tested. High contents of alkaline earth metals such as CaO resulted in high ash melting points of up to 1450 °C. Life Cycle Assessment results showed the lowest ecological impact for Sida pellets taking all production parameters and environmental categories into consideration, showing further advantages of Sida over other alternative biomasses. Overall, the results indicate the improved applicability of pelletized Sida biomass as a renewable biogenic energy carrier for combustion.
  • Publication
    Optimization of the fractional collection efficiencies for electrostatic precipitators used in biomass-fired boilers
    ( 2020) ;
    Steiner, Michael
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    Hebauer, M.
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    Beer, S.
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    Kramb, J.
    Electrostatic precipitators (ESPs) are commonly used for dust removal in flue gases from biomass-fired boilers. ESPs are able to precipitate the PM10 fraction (Nussbaumer, 2010) [1]. According to literature, ESPs have are duced fractional collection efficiency (FCE) in the range of 0.2-2 mm with a minimum at about 0.7 mm (Kaltschmitt et al., 2016; Fritz and Kern, 1992; Lützke and Wilkes, 1981) [2-4]. In the research project ""Optimization of the fractional collection efficiencies for electrostatic precipitators used in biomass-fired boilers(FRESBI)"" the FCEs for three commercial available ESPs (OekoTube Inside - Co. Oekosolve, Filterbox S - Co. Schraeder, Filterbox 2K - Co. Schraeder) were examined. The particle size distributions in the flue gas were measured using a Scanning Mobility Particle Sizer (SMPS) and a 13 stage Dekati® Low Pressure Impactor (DLPI).The combination of both measuring methods was a successful setup with various symbiotic effects. Additionally a mathematic model for the prediction of the FCEs of tubular ESPs was developed und successfully validated. For two ESPs (OekoTube Inside and Filterbox S) optimization measures were implemented, tested and evaluated. The applied measures focused on the optimization of the electrical field strength, hence increasing the performance of the ESPs. For the Filterbox S an increased FCE was achieved.
  • Publication
    Soybean Fertilized by P-Phases from Bagasse-Based Materials: P-Extraction Procedures, Diffusive Gradients in Thin Films (DGT), and X-ray Diffraction Analysis (XRD)
    ( 2020)
    Herzel, Hannes
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    Dombinov, Vitalij
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    Vogel, Christian
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    Willbold, Sabine
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    Vettorazzi Levandowski, Gabriel
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    Müller, Felix
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    Zang, Joachim Werner
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    Fonseca-Zang, Warde Antonieta da
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    Jablonowski, Nicolai David
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    Schrey, Silvia Diane
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    Adam, Christian
    The Brazilian sugarcane industry produced around 173 million tons (Mt) of bagasse in 2018. Bagasse is a by-product of juice extraction for ethanol and sugar production and is combusted in order to generate power, producing up to 10 Mt of ash per year. This ash contains various concentrations of plant nutrients, which allow the ash to be used as a crop fertilizer. However, the concentration and extractability of phosphorus (P), an essential plant nutrient, are low in bagasse ash. To increase the P content, we co-gasified and co-combusted bagasse with P-rich chicken manure. The resulting ash was thermochemically post-treated with alkali additives (Na2SO4 and K2SO4) to increase the availability of P to plants. We aimed to: (i) investigate the effect of thermochemical post-treatment of co-gasification residue and co-combustion ash on P availability to soybeans, (ii) explore the potential of chemical extraction methods (citric acid, neutral ammonium citrate, formic acid, and Mehlich-I) and diffusive gradients in thin films (DGT) to predict the availability of P to soybeans, and (iii) identify the responsible P-phases using X-ray diffraction . We evaluated P availability to soybeans growing in Brazilian Oxisol soil in two independent greenhouse pot experiments. The positive effect of thermochemical treatment on P availability from gasification residue was confirmed through the observation of increased P uptake and biomass in soybean plants. These findings were confirmed by chemical extraction methods and DGT. The gasification residue contained whitlockite as its main P-bearing phase. Thermochemical post-treatment converted whitlockite into highly soluble CaNaPO4. In contrast, co-combustion ash already contained highly soluble Ca(Na,K)PO4 as its main P-bearing phase, making thermochemical post-Agronomy 2020, 10, 895 2 of 24treatment unnecessary for increasing P availability. In conclusion, increased extractability and availability of P for soybeans were closely connected to the formation of calcium alkali phosphate. Our findings indicate that this combined methodology allows for the prediction of P-fertilization effects of ash.
  • Publication
    Untersuchungen zur möglichen Freisetzung von Nanopartikeln bei der Ablagerung und bodenbezogenen Anwendung von mineralischen Abfällen. Abschlussbericht
    (UBA, 2020) ; ; ;
    Hennecke, Dieter
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    Hund-Rinke, Kerstin
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    Meisterjahn, Boris
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    Schröder, Nicola
    Erste wissenschaftliche Studien zum Verbleib von technischem Nanomaterial (ENM) in Abfallverbrennungsanlagen [BÖR16, LAN16, WAL12, BAR16] deuten darauf hin, dass der Großteil der verwendeten ENM in den festen Verbrennungsrückständen verbleibt, wobei es möglicherweise nicht dauerhaft in diesen gebunden wird [WAL12]. Dementsprechend verlagert sich der Fokus der Untersuchungen hin zu nachgelagerten Schritten in der Verwertung bzw. Entsorgung der nanomaterialhaltigen mineralischen Rückstände aus der Verbrennung. Dies wurde zum Anlass genommen, um im Rahmen des zweijährigen UFOPLAN-Vorhabens ""Untersuchungen zur möglichen Freisetzung von Nanopartikeln bei der Ablagerung und bodenbezogenen Anwendung von mineralischen Abfällen"" mögliche Emissionspfade für aus der Hausmüll- bzw. Klärschlammverbrennung stammende Nanopartikel mithilfe von Laborversuchen zu untersuchen. Als ENM wurde nanoskaliges Titandioxid (nTiO2) in Form des Produkts Hombikat UV 100 WP der Fa. Venator eingesetzt. Nach der Herstellung ENM-haltiger HMV-Schlacken und Klärschlammaschen in großtechnischen Abfallbehandlungsanlagen, wurden diese in Laborversuchen hinsichtlich ihres Staubungs- und Elutionsverhaltens untersucht. Bei den Staubungsversuchen wurde bei Proben mit geringem Wasseranteil Titan sowohl bei den untersuchten HMV-Schlacken als auch bei den Klärschlammaschen in der alveolengängigen, der thorakalen und der einatembaren Fraktion des Staubs in höherer Konzentration als bei der Referenz detektiert. Bei den nassen Schlacken - welche typischerweise den Verhältnissen in der Praxis entsprechen - konnte Titan nur im thorakalen Staub gegenüber der Referenzprobe nachgewiesen werden. Neben den Staubungsversuchen wurden auch Elutionsversuche durchgeführt. In den Untersuchungen konnte gezeigt werden, dass standardisierte Labor-Elutionsverfahren in der Lage sind, im Vergleich mit Kontrollmaterialien erhöhte Mobilität von nTiO2 sicher anzuzeigen. Die beobachtete erhöhte Mobilität im Laborversuch konnten in Simulationsversuchen im Technikumsmaßstab bestätigt werden. Dort, wo die Elutionsversuche keine erhöhte Mobilität anzeigte, trat sie auch im Simulationsversuch nicht auf.