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- ItemInfluence of Tree Species, Harvesting Method and Storage on Energy Demand and Wood Chip Quality When Chipping Poplar, Willow and Black Locust(Basel : MDPI AG, 2020) Pecenka, Ralf; Lenz, Hannes; Jekayinfa, Simeon Olatayo; Hoffmann, ThomasThe cultivation of fast-growing wood (e.g., poplar, willow or black locust) in short rotation coppices and agroforestry systems presents an opportunity for producing biomass sustainably in the agricultural sector. Cost-efficient agricultural wood production requires the availability of high-performance machinery and methods with which high-quality wood chips can be produced at low cost. It is known from harvesting short rotation coppices in practice that both the wood chip quality and the performance of the harvesting machinery depend on a variety of factors (e.g., harvesting method, weather conditions, tree species). That is why this study examines in detail the influence of the tree species (different varieties of poplar, willow, black locust) and the wood condition (fresh, stored or dried, frozen) on the specific energy demand for comminution in a stationary drum chipper and on the particle size distribution of the wood chips produced. For all the tree species examined, the chipping of dried as well as frozen stems was connected with a significant increase in the specific energy demand for comminution. An increase of 31% has been measured if poplar stems are chipped in frozen conditions (max. 6.31 kWh t−1). Drying led to an increase of 59% for dried willow stems (max. 6.67 kWh t−1). Drying and frost had also an influence on the size and quality of the wood chips, but no globally significant connection could be established for the examined tree varieties.
- ItemReinigungstechnologien in der Naturfaseraufbereitung(Darmstadt : KTBL, 2012) Lühr, Carsten; Pecenka, Ralf; Fürll, Christian; Hoffmann, ThomasMit einer neuartigen Reinigungstechnologie kann ein Nebenprodukt aus der Naturfaseraufbereitung, das Schäben-Faser-Gemisch, effektiv aufbereitet werden. Außer zurückgewonnenen Kurzfasern können gereinigte Schäben in hochwertiger Qualität der Industrie zur Verfügung gestellt werden. Die Wirtschaftlichkeit von Faseraufschlussanlagen wird durch die Vermarktung der gereinigten Zwischenprodukte, der einfachen Konstruktion und der damit kostengünstigen Reinigungsmaschine verbessert. Ziel dieser Untersuchung ist es, durch Simulation der Materialströme beim Reinigungsvorgang, mithilfe der Diskreten Elemente Methode (DEM) und der Variation der Maschinenparameter, eine Optimierung der Reinigungsmaschine zu erreichen.
- ItemProcess Analysis of Main Organic Compounds Dissolved in Aqueous Phase by Hydrothermal Processing of Açaí (Euterpe oleraceae, Mart.) Seeds: Influence of Process Temperature, Biomass-to-Water Ratio, and Production Scales(Basel : MDPI, 2021) da Silva, Conceição de Maria Sales; de Castro, Douglas Alberto Rocha; Santos, Marcelo Costa; Almeida, Hélio da Silva; Schultze, Maja; Lüder, Ulf; Hoffmann, Thomas; Machado, Nélio TeixeiraThis work aims to systematically investigate the influence of process temperature, biomass-to-water ratio, and production scales (laboratory and pilot) on the chemical composition of aqueous and gaseous phases and mass production of chemicals by hydrothermal processing of Açaí (Euterpe oleraceae, Mart.) seeds. The hydrothermal carbonization was carried out at 175, 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10; at 250 °C at 2 °C/min and biomass-to-water ratios of 1:10, 1:15, and 1:20 in technical scale; and at 200, 225, and 250 °C at 2 °C/min and a biomass-to-water ratio of 1:10 in laboratory scale. The elemental composition (C, H, N, S) in the solid phase was determined to compute the HHV. The chemical composition of the aqueous phase was determined by GC and HPLC and the volumetric composition of the gaseous phase using an infrared gas analyzer. For the experiments in the pilot test scale with a constant biomass-to-water ratio of 1:10, the yields of solid, liquid, and gaseous phases varied between 53.39 and 37.01% (wt.), 46.61 and 59.19% (wt.), and 0.00 and 3.80% (wt.), respectively. The yield of solids shows a smooth exponential decay with temperature, while that of liquid and gaseous phases showed a smooth growth. By varying the biomass-to-water ratios, the yields of solid, liquid, and gaseous reaction products varied between 53.39 and 32.09% (wt.), 46.61 and 67.28% (wt.), and 0.00 and 0.634% (wt.), respectively. The yield of solids decreased exponentially with increasing water-to-biomass ratio, and that of the liquid phase increased in a sigmoid fashion. For a constant biomass-to-water ratio, the concentrations of furfural and HMF decreased drastically with increasing temperature, reaching a minimum at 250 °C, while that of phenols increased. In addition, the concentrations of CH3COOH and total carboxylic acids increased, reaching a maximum concentration at 250 °C. For constant process temperature, the concentrations of aromatics varied smoothly with temperature. The concentrations of furfural, HMF, and catechol decreased with temperature, while that of phenols increased. The concentrations of CH3COOH and total carboxylic acids decreased exponentially with temperature. Finally, for the experiments with varying water-to-biomass ratios, the productions of chemicals (furfural, HMF, phenols, cathecol, and acetic acid) in the aqueous phase is highly dependent on the biomass-to-water ratio. For the experiments at the laboratory scale with a constant biomass-to-water ratio of 1:10, the yields of solids ranged between 55.9 and 51.1% (wt.), showing not only a linear decay with temperature but also a lower degradation grade. The chemical composition of main organic compounds (furfural, HMF, phenols, catechol, and acetic acid) dissolved in the aqueous phase in laboratory-scale study showed the same behavior as those obtained in the pilot-scale study.
- ItemSamengewinnung während der Schwadbearbeitung am Beispiel Hanf(Darmstadt : KTBL, 2013) Budde, Jörn; Gusovius, Hans-Jörg; Hoffmann, Thomas; Ola, Daniel-CalinUnter den klimatischen Bedingungen Nord- und Mitteldeutschlands ist die klassische Ernte von Hanfsamen mit Mähdreschern nicht oder nur schwer realisierbar. Aus diesem Grund werden eine innovative Maschinenlösung sowie eine Verfahrenskette zur Bergung möglichst homogen und vollständig abgereifter Samen aus der Schwade entwickelt. Zur Untersuchung des Nachreifeverhaltens und der Ausfallverluste wurden Versuchsschwaden angelegt. An diesen wurde untersucht, inwieweit Schnittzeitpunkt und Nachreifezeit die Samenqualität und -quantität sowie die Ausfallverluste beeinflussen. Die Ergebnisse zeigen, dass im Jahr 2012 eine Erzeugung hochwertiger Fasern bei gleichzeitig hohen Samenerträgen in einem Zeitfenster von 9 Tagen möglich gewesen wäre. Die maximalen Samenerträge betrugen 364 kg TM/ha für die Sorte Santhica 27 und 1 060 kg TM/ha für die Sorte Fedora 17. Den höchsten Samenverlust durch Ausfallen (22 %) zeigte die Sorte Fedora 17, wobei dieser nach dem Zeitpunkt des maximalen Ertrages auftrat.
- ItemImmer noch speziell? – Verfahren zur Ernte von Faserhanf(Darmstadt : KTBL, 2016) Gusovius, Hans-Jörg; Hoffmann, Thomas; Budde, Jörn; Lühr, CarstenEtwa zwanzig Jahre nach der Wiederzulassung des Hanfanbaus in Deutschland steht eine Vielzahl unterschiedlicher Ernteverfahren zur Verfügung. Etablierte, aber auch neuere Maschinenentwicklungen erlauben die Bereitstellung von Rohstoffen für die industrielle Weiterverarbeitung oder für die Verwendung als Nahrungs- oder Futtermittel. Der erforderliche Spezialisierungsgrad führt zwar zu hohen, aber – im Vergleich zu etablierten Kulturen – nicht außergewöhnlichen Verfahrenskosten. In der vorliegenden Studie wurden bestehende Erntesysteme unter heimischen Anbaubedingungen analysiert. Technische Weiterentwicklungen sind jedoch erforderlich, um die Wettbewerbssituation sowohl um Anbauflächen als auch der aus Faserhanf hergestellten Halbzeuge und Produkte zu verbessern.
- ItemEstablishment of a Laboratory Scale Set-Up with Controlled Temperature and High Humidity to Investigate Dry Matter Losses of Wood Chips from Poplar during Storage(Basel : MDPI, 2022) Hernandez-Estrada, Albert; Pecenka, Ralf; Dumfort, Sabrina; Ascher-Jenull, Judith; Lenz, Hannes; Idler, Christine; Hoffmann, ThomasThe aim of this work was to improve the understanding of dry matter losses (DML) that occur in wood chips during the initial phase of storage in outdoor piles. For this purpose, a laboratory scale storage chamber was developed and investigated regarding its ability to recreate the conditions that chips undergo during the initial phase of outdoor storage. Three trials with poplar Max-4 (Populus maximowiczii Henry Populus nigra L.) chips were performed for 6–10 weeks in the storage chamber under controlled temperature and assisted humidity. Two different setups were investigated to maintain a high relative humidity (RH) inside the storage chamber; one using water containers, and one assisted with a humidifier. Moisture content (MC) and DML of the chips were measured at different storage times to evaluate their storage behaviour in the chamber. Additionally, microbiological analyses of the culturable fraction of saproxylic microbiota were performed, with a focus on mesophilic fungi, but discriminating also xerophilic fungi, and mesophilic bacteria, with focus on actinobacteria, in two trials, to gain a view on the poplar wood chip-inhabiting microorganisms as a function of storage conditions (moisture, temperature) and time. Results show that DML up to 8.8–13.7% occurred in the chips within 6–10 storage weeks. The maximum DML were reached in the trial using the humidifier, which seemed a suitable technique to keep a high RH in the testing chamber, and thus, to analyse the wood chips in conditions comparable to those in outdoor piles during the initial storage phase.