Wood Chips

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Sylvain Salvador - One of the best experts on this subject based on the ideXlab platform.

  • Quantification of the torrefaction effects on the grindability and the hygroscopicity of Wood Chips
    Fuel, 2017
    Co-Authors: Baptiste Colin, Jean-louis Dirion, Patricia Arlabosse, Sylvain Salvador
    Abstract:

    In the field of biomass torrefaction, lots of product properties have been widely investigated at the lab scale but some uncertainties remain about the gains in terms of grindability and hygroscopicity of torrefied products. In this study, beech Wood Chips (with an initial moisture content of 10-12%) have been torrefied in a pilot-scale rotary kiln. The torrefaction severity was controlled by adjusting the temperature, the treatment duration and the solid hold-up in the kiln. Mass losses ranging between 1.7% and 25% have been obtained. Properties of torrefied Wood Chips were then analyzed in terms of composition, heat content, hygroscopicity and grinding energy requirement. Dynamic vapor sorption measurements show that a minimum of hygroscopicity is reached for a mass loss (ML) between 1.7 and 7.8%. The moisture uptakes for mass losses above this optimum remain stable at values twice lower than that of raw biomass. Finally, a new method is proposed to estimate the grindability of Wood Chips. This method takes into account the grinding energy consumption and the particle size distribution of ground samples. A reduction by a factor of 6.3 of the apparent specific surface grinding energy is observed between a moisture content of 41% and the dryness. This energy measurement is in turn reduced by a further factor of 8.1 after torrefaction with a 25% mass loss.

  • Wood Chips flow in a rotary kiln: experiments and modeling
    Chemical Engineering Research and Design, 2015
    Co-Authors: Baptiste Colin, Jean-louis Dirion, Patricia Arlabosse, Sylvain Salvador
    Abstract:

    Rotary kilns are well suited for processing Woody biomass by torrefaction to produce bioenergy. One of the key issues for process design lies in the flow pattern modeling. The Saeman model is classically used to predict the mean residence time (MRT) and the bed depth profile of powder materials in rotary kilns. Its ability to describe Wood Chips flow arises. In the present study, residence time distribution (RTD) experiments are conducted with raw and torrefied Wood Chips. Effects of operating parameters – kiln slope, rotational speed and inlet flow-rate – on the average residence time, the variance and the mean solid hold-up are discussed. A plug flow with small extent of dispersion is emphasized, even if some segregation phenomena are highlighted. Torrefaction did not evidence any significant influence on the flow pattern. With a discrepancy of 20 % between the measured and computed mean residence time, the predictive capacity of the classical Seaman model proved to be insufficient. The model is adapted to predict accurately the load profile and the mean residence time of particles with parallelepiped form. The discrepancy between experimental and calculated results is so reduced from 20 to 5 % for the MRT and from 25 to 5 % for the mean solid hold-up.

Michihiko Momota - One of the best experts on this subject based on the ideXlab platform.

  • Evaluation of danger from fermentation-induced spontaneous ignition of Wood Chips.
    Journal of Hazardous Materials, 2005
    Co-Authors: Hiroshi Koseki, Michihiko Momota
    Abstract:

    Abstract Recently we conducted investigations in biological wastes because large pile-up storage of waste Wood Chips and others caused many fires in Japan. This paper shows the experimental results on Wood Chips with thermal analysis, by using a Thermogravimetry–differential thermal analysis (TG–DTA) and micro calorimeters, and as well with spontaneous ignition measurements, such as a UN wire mesh cube tester and a spontaneous ignition tester (SIT). Exothermic reaction of Wood Chips was observed during 45–60 °C only by the high sensitive microcalorimeters, TAM and MS 80. This reaction is far apart from the second major reaction by oxidation and is not easy to be recognized by the conventional detectors, like the TG–DTA and the wire mesh cube tester, because their sensitivity cannot meet the strict requirement. Correspondingly, experimental results under the adiabatic condition in the SIT confirmed this theory, in which the onset temperature of spontaneous ignition of Wood Chips was measured as 50–80 °C. This implies that the weak initial reaction at ambient temperatures mainly results from microbial fermentation in the presence of its inherent moisture and possibly gives rise to the further intense combustion sustained by a chemical reaction if the heat cannot be removed from the large scale storage of Wood Chips.

  • Evaluation of danger from fermentation-induced spontaneous ignition of Wood Chips.
    Journal of hazardous materials, 2005
    Co-Authors: Hiroshi Koseki, Michihiko Momota
    Abstract:

    Recently we conducted investigations in biological wastes because large pile-up storage of waste Wood Chips and others caused many fires in Japan. This paper shows the experimental results on Wood Chips with thermal analysis, by using a Thermogravimetry-differential thermal analysis (TG-DTA) and micro calorimeters, and as well with spontaneous ignition measurements, such as a UN wire mesh cube tester and a spontaneous ignition tester (SIT). Exothermic reaction of Wood Chips was observed during 45-60 degrees C only by the high sensitive microcalorimeters, TAM and MS 80. This reaction is far apart from the second major reaction by oxidation and is not easy to be recognized by the conventional detectors, like the TG-DTA and the wire mesh cube tester, because their sensitivity cannot meet the strict requirement. Correspondingly, experimental results under the adiabatic condition in the SIT confirmed this theory, in which the onset temperature of spontaneous ignition of Wood Chips was measured as 50-80 degrees C. This implies that the weak initial reaction at ambient temperatures mainly results from microbial fermentation in the presence of its inherent moisture and possibly gives rise to the further intense combustion sustained by a chemical reaction if the heat cannot be removed from the large scale storage of Wood Chips.

Antoni Rius - One of the best experts on this subject based on the ideXlab platform.

  • Comparative cost evaluation of heating oil and small-scale Wood Chips produced from Euro-Mediterranean forests
    Renewable Energy, 2015
    Co-Authors: Bernat Esteban, Jordi-roger Riba, Grau Baquero, Antoni Rius
    Abstract:

    This work performs a cost evaluation of small-scale produced Wood Chips from forests in the Euro-Mediterranean region to be used for heating purposes. The study is focused on forests located in the Argencola municipality (Catalonia, northeastern Spain). The use of such easy-to-produce biofuel is appealing since it may be used as a valid substitute of heating oil to produce thermal energy in the same area where it is produced, thus minimizing transportation requirements and reducing dependence on the rising prices of heating oil. Additionally, it allows facing environmental and social concerns related to the current lack of management in the forests under analysis, which has led to an important increase in the biomass stock and wildfires risk. As wildfires in the Euro-Mediterranean region generate important impacts, an average economic cost of wildfires has been evaluated in this paper. The economic assessment of small-scale production and consumption of Wood Chips as proposed in this study has shown interesting economic benefits when compared with current heating oil prices. Results indicate that it is a realistic option since production costs range from 12.2 €/GJ to 18.5 €/GJ depending on the applied forestry practices, whereas current cost of heating oil is about 23.9 €/GJ. A sensitivity analysis has also been conducted to assess the impact of the data with higher uncertainty on the final results. It has been shown that the key factors that determine the viability of the proposed model are heating oil price, biomass stock growth rate, transportation requirements and applied forest management practices. Results presented prove that Wood Chips cost is quite independent of fossil fuel prices, thus higher fossil fuel prices greatly favors the use of Wood Chips when produced and consumed in the same area, thus minimizing transportation requirements. In addition, higher biomass growth rates than those considered in this work may reduce the final cost of small-scale produced Wood Chips.

  • environmental assessment of small scale production of Wood Chips as a fuel for residential heating boilers
    Renewable Energy, 2014
    Co-Authors: Bernat Esteban, Jordi-roger Riba, Grau Baquero, Rita Puig, Antoni Rius
    Abstract:

    This work performs a comparative life cycle assessment (LCA) of two fuels for heating boilers, namely Wood Chips and oil. The LCA methodology allows comparing the environmental impacts of the two analyzed fuels, thus assessing which is environmentally more advantageous. The study is focused on Mediterranean forests located in the Argencola region (Catalonia, northeastern Spain) by applying forest management practices focused to ensure a sustainable exploitation. The direct use of Wood Chips as a fuel for boilers simplifies notably the number of processes involved in producing such a fuel. The results presented clearly show the environmental benefits of using small-scale produced Wood Chips instead of fossil oil by analyzing representative impact categories defined by the CML and EDIP methods, even when considering the changes in the carbon stock in the forests under analysis due to the management approach adopted. A sensitivity analysis has also been conducted to assess the impact of the data with higher uncertainty on the final LCA results.

Anders Rasmuson - One of the best experts on this subject based on the ideXlab platform.

  • Dynamic simulation of disintegration of Wood Chips caused by impact and collisions during the steam explosion pretreatment
    Wood Science and Technology, 2017
    Co-Authors: Muhammad Muzamal, Anders Rasmuson
    Abstract:

    Steam explosion (SE) pretreatment produces damaged and disintegrated biomass with a large surface area which facilitates enzymatic hydrolysis for the production of biofuels and other value-added chemicals. It was observed during experiments that Wood Chips disintegrate into smaller pieces because of collisions and impact with each other and the walls of the SE equipment. In this study, these events were simulated using the finite element method. Wood Chips were simulated in this model as a linear elastic material until failure. The damage initiation was identified using Hashin’s damage initiation criteria. Once the damage was initiated, additional loading caused the evolution of damage, i.e. degradation and breakage of the material, which was modelled using the material property degradation model and deletion of the failed elements. Elastic and strength properties of spruce Wood were estimated at ambient conditions (12 % moisture content at 20 °C) and at SE conditions (30 % moisture content at 160 °C). Comparison of simulations performed using material properties at ambient and SE conditions revealed that the damage in Wood Chips significantly increased because of the steam treatment. The effects of Wood chip velocity and orientation at the time of impact were studied as well. It was found that Wood Chips moving at high velocity and impacting with the steel wall in the radial direction acquire the most damage.

  • Steam drying of Wood Chips in pneumatic conveying dryers
    Drying Technology, 1997
    Co-Authors: Christian Fyhr, Anders Rasmuson
    Abstract:

    ABSTRACT A model for a pneumatic conveying dryer is presented. Although the main emphasis is put on superheated steam drying of Wood Chips, it can be used for other porous materials as well The model includes a comprehensive two-dimensional model for the drying of single Wood Chips which accounts for the main physical mechanisms occurring in Wood during drying. The external drying conditions in a pneumatic conveying dryer were calculated by applying the mass, heat and momentum equations for each incremental step in dryer length. A plug flow assumption was made for the dryer model and the single particle and dryer models were solved in an iterative manner. The non-spherical nature of Wood Chips were accounted for by measuring the drag and heat transfer coefficients Model calculations illustrate the complex interactions between steam, particles and walls which occur in a flash dryer. The drying rate varies in a very complex manner through the dryer. The internal resistance to mass transfer becomes very impo...

  • Some aspects of the modelling of Wood Chips drying in superheated steam
    International Journal of Heat and Mass Transfer, 1997
    Co-Authors: Christian Fyhr, Anders Rasmuson
    Abstract:

    Abstract A comprehensive two-dimensional model is used to simulate the drying of Wood Chips in superheated steam. Emphasis is put on the drying conditions present in a pneumatic conveying dryer, i.e. high heat transfer rates and pressures. The internal mass transfer for these conditions limits the drying rate and, for a successful dimensioning of such dryer, not only the conditions inside the dryer but also the mechanisms occurring inside the single chip must be well understood. Wood Chips of different sizes and species are studied. The effect of varying inlet temperatures of the Chips (preheating), as well as the flashing effect at the outlet when the pressure drops (postdrying), are investigated. Different design parameters, such as the value of the heat transfer coefficient and the necessity of a two-dimensional model for the single Wood chip, are also discussed.

Baptiste Colin - One of the best experts on this subject based on the ideXlab platform.

  • Quantification of the torrefaction effects on the grindability and the hygroscopicity of Wood Chips
    Fuel, 2017
    Co-Authors: Baptiste Colin, Jean-louis Dirion, Patricia Arlabosse, Sylvain Salvador
    Abstract:

    In the field of biomass torrefaction, lots of product properties have been widely investigated at the lab scale but some uncertainties remain about the gains in terms of grindability and hygroscopicity of torrefied products. In this study, beech Wood Chips (with an initial moisture content of 10-12%) have been torrefied in a pilot-scale rotary kiln. The torrefaction severity was controlled by adjusting the temperature, the treatment duration and the solid hold-up in the kiln. Mass losses ranging between 1.7% and 25% have been obtained. Properties of torrefied Wood Chips were then analyzed in terms of composition, heat content, hygroscopicity and grinding energy requirement. Dynamic vapor sorption measurements show that a minimum of hygroscopicity is reached for a mass loss (ML) between 1.7 and 7.8%. The moisture uptakes for mass losses above this optimum remain stable at values twice lower than that of raw biomass. Finally, a new method is proposed to estimate the grindability of Wood Chips. This method takes into account the grinding energy consumption and the particle size distribution of ground samples. A reduction by a factor of 6.3 of the apparent specific surface grinding energy is observed between a moisture content of 41% and the dryness. This energy measurement is in turn reduced by a further factor of 8.1 after torrefaction with a 25% mass loss.

  • Wood Chips flow in a rotary kiln: experiments and modeling
    Chemical Engineering Research and Design, 2015
    Co-Authors: Baptiste Colin, Jean-louis Dirion, Patricia Arlabosse, Sylvain Salvador
    Abstract:

    Rotary kilns are well suited for processing Woody biomass by torrefaction to produce bioenergy. One of the key issues for process design lies in the flow pattern modeling. The Saeman model is classically used to predict the mean residence time (MRT) and the bed depth profile of powder materials in rotary kilns. Its ability to describe Wood Chips flow arises. In the present study, residence time distribution (RTD) experiments are conducted with raw and torrefied Wood Chips. Effects of operating parameters – kiln slope, rotational speed and inlet flow-rate – on the average residence time, the variance and the mean solid hold-up are discussed. A plug flow with small extent of dispersion is emphasized, even if some segregation phenomena are highlighted. Torrefaction did not evidence any significant influence on the flow pattern. With a discrepancy of 20 % between the measured and computed mean residence time, the predictive capacity of the classical Seaman model proved to be insufficient. The model is adapted to predict accurately the load profile and the mean residence time of particles with parallelepiped form. The discrepancy between experimental and calculated results is so reduced from 20 to 5 % for the MRT and from 25 to 5 % for the mean solid hold-up.