Hochschule für Technik und Umwelt FHNW

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  • Kein Vorschaubild vorhanden
    Publikation
    Holzvergasung von PU-verleimtem Restholz
    (Hochschule für Technik FHNW, 24.06.2024) Oester, Marc; Batu, Shevin; Baumann, Mario; Kamber, Sebastian; Wacker, Gian; Mandaliev, Petar; Dr. Horst Matzke
    Die Ergebnisse der vorliegenden Arbeit zeigen, dass die Verwertung von PU verleimtem Restholz aus der Verarbeitung von Holzprodukten in einem lokalen Holzheizkraftwerk wie der LiPRO Anlage der Flück AG eine vielversprechende und ökologisch sowie ökonomisch sinnvolle Verwertungsmöglichkeit darstellen kann. Das anfallende Restholz unterscheidet sich hinsichtlich der Holzart (hauptsächlich Tanne und Fichte) nicht von naturbelassenen Waldholzhackschnitzeln. Ein Teil des Restholzes enthält Polyurethanleim aus der Verleimung der Holzkomponenten. Bei einer angenommenen Leimfugendicke von durchschnittlich 0.1 mm ergeben sich für die gängigsten Restholzstücke aus dem Abbundbetrieb der Flück AG durchschnittliche Mengen von < 0.6 bis < 11.9 Liter PU-Leim pro Kubikmeter Holz. Eine Vorbehandlung des Holzes bei diesen geringen Mengen PU-Leim zur Entfernung der Leimschicht ist nach heutigem Stand der Technik weder ökologisch noch ökonomisch sinnvoll. Die Auswertung der externen Messungen hat gezeigt, dass bei der Verbrennung und Vergasung von naturbelassenen Holzschnitzeln im Holzheizkraftwerk der Firma Flück AG Emissionswerte resultieren, welche die Vorgaben der LRV deutlich unterschreiten. Für die überwiegende Zahl der Parameter existieren jedoch keine LRV-Grenzwerte für den gemessenen Anlagentyp (siehe Bericht NoxaQuant, Anhang F). Es ist denkbar, dass auch für PU-verleimtes Restholz die Emissionswerte im gesetzlich gegebenen Rahmen bleiben. Dies sollte allerdings für verschiedene Kombinationen von Holzresten überprüft werden.
    11 - Studentische Arbeit
  • Kein Vorschaubild vorhanden
    Publikation
    Identification of organic acids in secondary organic aerosol and the corresponding gas phase from chamber experiments
    (American Chemical Society, 15.10.2004) Fisseha, Rebeka; Dommen, Josef; Sax, Mirjam; Paulsen, Dwane; Kalberer, Markus; Maurer, Rolf; Höfler, Frank; Weingartner, Ernest; Baltensperger, Urs
    Organic acids in the gas and aerosol phase from photooxidation of 1,3,5-trimethylbenzene in the presence of 300 ppb propene and 300 ppb NOx in smog chamber experiments were determined using a wet effluent diffusion denuder/aerosol collector coupled to ion chromatography (IC) with conductivity detection. Behind the IC, the samples were collected using a fraction collector, for identification of unresolved/unidentified organic acids with IC-mass spectrometry (MS). In total, 20 organic acids were found with MS of which 10 were identified. The organic acids identified offline by IC-MS were then further quantified based on the online IC data. The identification was additionally confirmed with gas chromatography-mass spectrometry. At the maximum aerosol concentration, organic acids comprised 20-45% of the total aerosol mass. The method has a detection limit of 10-100 ng/m3 for the identified carboxylic acids.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Kein Vorschaubild vorhanden
    Publikation
    Online gas and aerosol measurement of water soluble carboxylic acids in Zurich
    (Wiley, 2006) Fisseha, Rebeka; Dommen, Josef; Gäggeler, Kathrin; Weingartner, Ernest; Samburova, Vera; Kalberer, Markus; Baltensperger, Urs
    We discuss the diurnal and seasonal variability of low molecular weight organic acids in Zurich city on the basis of online quasi‐continuous measurement in the gas and aerosol phase using a wet effluent diffusion denuder/aerosol collector (WEDD/AC) coupled to ion chromatography. The measurements were performed during August–September 2002 and March 2003. Acetic acid exhibited the highest concentration in the gas phase during all the measurement periods, followed by formic acid. Oxalic acid was predominantly found in the aerosol phase and often below the detection limit in the gas phase. In addition, filter samples were analyzed using ion chromatography–mass spectrometry (IC‐MS) to provide more information on organic acids in the aerosol phase. From the offline IC‐MS measurements, 20 monocarboxylic, dicarboxylic, and tricarboxylic acids were determined. In addition, more than 20 different masses were detected with the MS; however, identification of the organic acids was not possible. The sum of the carboxylic acids contributed on average 2% to the water soluble organic carbon (WSOC). The fraction of dicarboxylic acids to the WSOC was higher in summer compared to winter suggesting that dicarboxylic acids are mainly a result of photochemical reactions in summer whereas in winter they mainly result from primary sources.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Kein Vorschaubild vorhanden
    Publikation
    Characterizing particulate emissions from wood burning appliances including secondary organic aerosol formation potential
    (Elsevier, 31.08.2017) Keller, Alejandro; Burtscher, Heinz
    Biomass burning is a major contributor to environmental particulate matter pollution and should therefore be contemplated by emission control legislation. However, policy decisions for improving air quality by imposing emission limits are only as good as the selected metric. We discuss an approach that incorporates recent scientific results and is compatible with type-approval testing and field measurements. We include potential secondary organic aerosol (SOA) by aging emissions in an oxidation flow reactor. Quantification is done by particle-bound total carbon analysis. Total carbon is the fraction relevant to combustion quality and a better marker for toxicity than total particulate matter, which also includes salts and ashes. The data is complemented by on-line size distribution measurements. We exemplify our approach by showing measurements performed on a variety of appliances. Our measurements suggest that non-methane hydrocarbons (NMHC) species with very low volatility are responsible for most of the SOA. Condensing and precipitating this fraction significantly reduces SOA potential but has no noticeable impact on total NMHC. Thus, key precursors of SOA may be a much smaller subset than previously thought. Targeting this fraction could be a straightforward SOA mitigation strategy. These results could not have been derived using the current standard emission control metrics.
    01A - Beitrag in wissenschaftlicher Zeitschrift