Numerical prediction of the mean residence time of solid materials in a pilot-scale rotary kiln

Haeldermans, Tom; Lataf, M.A.; Vanroelen, Giovanni; Samyn, Pieter; Vandamme, Dries; Cuypers, Ann; Vanreppelen, Kenny; Schreurs, Sonja

doi:10.1016/j.powtec.2019.06.008

Cited by 18 publications

(9 citation statements)

References 20 publications

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“…The TPS was obtained as the commercial product FlourPlast GP2 from Rodenburg Biopolymers (Oosterhout, The Netherlands). Biochar was made from a pine tree bark (Pinus sylvestris) residue stream at 450 °C and a residence time of around 12 min, using a lab-scale pyrolysis unit as described in [31]. Biochar was ground in a Retsch S1 planetary ball mill (Retsch, Haan, Germany) and sieved using a Retsch AS200 Basic sieving apparatus (Retsch, Haan, Germany) to achieve a mean particle size of 18.9 µm (P10 = 4.8 µm, P90 = 59.98 µm).…”

Section: Methodsmentioning

confidence: 99%

Bio‐Based Poly(3-hydroxybutyrate)/Thermoplastic Starch Composites as a Host Matrix for Biochar Fillers

et al. 2021

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Biochar is an excellent, but less-used candidate to serve as an alternative filler in poly(3hydroxybutyrate) (PHB)-based composites. Increasing amounts of biochar between 20 and 50 wt.% were incorporated in PHB/char and PHB/thermoplastic starch (TPS)/char composites and its effects on the microstructure, crystallization and thermal properties were investigated. PHB shows a significant reduction in molecular weight after processing and the increasing amounts of biochar decreases this even stronger. From thermogravimetric analysis, it was clear that the onset degradation temperature of the PHB/char composites (255 °C) is only slightly influenced by the biochar particles up to 40 wt.%. Contrastingly, this temperature reduces to 245 °C when 50 wt.% of biochar is added. Additional data confirm that morphology and crystallization kinetics are enhanced up to 40 wt.% of biochar, while even higher percentages of filler clearly have an opposite effect. Finally, this work reveals the ability of TPS to work as an excellent intermediator between biochar and PHB at biochar concentrations up to 20 wt.%, where degradation and resulting reduction in molecular weight remains limited as compared to that of the PHB/char sample. Furthermore, like biochar, TPS acts as a nucleation agent in the composites and removes the influence of the biochar on the thermal stability of the composites.

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Section: Methodsmentioning

confidence: 99%

Bio‐Based Poly(3-hydroxybutyrate)/Thermoplastic Starch Composites as a Host Matrix for Biochar Fillers

et al. 2021

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“…A detailed description of the pilot-scale reactor can be found in [20]. Biochar was produced in the pilot-scale reactor in a pyrolysis gas atmosphere in a single 8 h run for every biomass stream.…”

Section: Pyrolysismentioning

confidence: 99%

“…Biochar was produced in the pilot-scale reactor in a pyrolysis gas atmosphere in a single 8 h run for every biomass stream. Mean residence time (MRT) was determined theoretically using an adapted version of the Sullivan's equation as explained in [20]. The schematic representation of both reactors can be found in Figure S1.…”

Section: Pyrolysismentioning

confidence: 99%

An Experimentally Validated Selection Protocol for Biochar as a Sustainable Component in Green Roofs

Haeldermans

Torres

Vercruysse

et al. 2023

Waste

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Green roofs contribute to more sustainable cities, but current commercial substrates suffer from important limitations. If carefully selected, biochar could serve as a viable option for a more sustainable green roof substrate. We propose a protocol to select an optimal biochar for green roof substrate amendment. Coffee husks, medium-density fiberboard, palm date fronds, and a mixture of waste wood, tree bark, and olive stone kernels are selected as residues for biochar production to develop a selection protocol. The residues are pyrolyzed at 350, 450, 500, and 550 °C in a lab-scale reactor. A pyrolysis temperature of 450 °C is selected for upscaling and is based on biochar yield, pH, salinity, and elemental composition. From evaluating the biochar characteristics after upscaling, it can be concluded that the biochar’s carbonization degree is mainly controlled by pyrolysis temperature, while yield, pH, and salinity are more dependent on the biomass properties. Ultimately, our procedure evaluates the presence of important contaminants, the biochar’s water holding capacity, salinity, pH, and carbonization degree. To validate the developed protocol, plant coverage experiments on green roofs are performed, which are quantified using a novel digital image processing method, demonstrating its efficient use to facilitate future biochar selection in substrates.

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“…Residence time distribution (RTD) and mean residence time were critical and quantitative properties describing the complex motion behaviors of particles in the rotary heat exchanger. − Researchers paid more attention to measuring the residence time of biomass materials in reactors in pretreatment processes. − Moreover, transport processing control and equipment design could be guided by these key properties. Several numerical methods could be adopted to obtain detailed information about the mixing process in a bed of spherical and spherical-like biofuel particles on grate firing systems. − However, the number of gasifiable fuels and the efficiency of gasification processes were directly affected by the heat requirement for drying pretreatment. The heat and mass transfer processes of biomass fuels were significantly influenced by the motion behaviors of biomass particles in drying equipment. − A considerable number of studies were carried out on the development of residence time of nonspherical biomass particles within a variety of rotary cylinders.…”

Section: Introductionmentioning

confidence: 99%

Visual Experimental Analysis of the Residence Time of Flexible Biomass Particles in a Baffled Rotating Cylindrical Tube

Zhang

Pan

et al. 2020

Energy Fuels

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Drying of biomass or biofuels is a major issue during pretreatment because of a high initial moisture content, which results in low energy efficiency and combustion temperature and high emission of hydrocarbons. As the motion behaviors of biomass fuels play an important role in the drying process, it is of great significance to investigate the motion of biomass. In this study, visualization experiments on the motion of flexible nonspherical biomass particles in a baffled rotating cylindrical tube were performed. The residence time of biomass particles was obtained and analyzed by taking into account gas velocity, mass flow rate of flexible biomass, initial moisture content of biomass particles, slope and rotational speed of the cylindrical tube, and other parameters under several operational conditions. The results indicated that the mean residence time of flexible biomass increased with the increase in the mass flow rate and initial moisture content and decreased with the increase of the cylindrical tube’s rotational speed and slope and the velocity of the gas phase. Despite the quite small sliding friction coefficient between the tube’s inner wall and biomass particles, a larger slope could lead to stronger sliding friction force in the axial direction when these biomass particles moved to the bottom of the tube. Mean residence time is observed to decrease significantly and gradually decrease with the increase in rotational speed from 6 to 9 rpm and from 9 to 18 rpm, respectively. In addition, the mean residence time increased from 78.5 to 99.4 s when the inlet mass flow rate increased from 60 to 240 kg/h without the gas phase, but it increased from 57.4 to 78.5 s within the same range of the inlet mass flow rate at a gas velocity of 0.3 m/s.

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Numerical prediction of the mean residence time of solid materials in a pilot-scale rotary kiln

Cited by 18 publications

References 20 publications

Bio‐Based Poly(3-hydroxybutyrate)/Thermoplastic Starch Composites as a Host Matrix for Biochar Fillers

Bio‐Based Poly(3-hydroxybutyrate)/Thermoplastic Starch Composites as a Host Matrix for Biochar Fillers

An Experimentally Validated Selection Protocol for Biochar as a Sustainable Component in Green Roofs

Visual Experimental Analysis of the Residence Time of Flexible Biomass Particles in a Baffled Rotating Cylindrical Tube

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