Thorium-based CANDU qualification as plutonium burner

Converting the weapon grade Plutonium from the U.S.A., Russia, U.K. etc. to Mixed OXide fuel and using it in power reactors was seen as a feasible way to both dispose Plutonium and produce energy. Using Thorium-based fuels in CANDU has been investigated since early 1980’s, they were designed and tested in Canada as mixed ThO2 -UO 2 (both LEU and HEU) and mixed ThO2 -PuO 2, (both reactor- and weapons-grade) ([1]). In this respect, Thorium might also be seen as a valuable driver for weapon grade Plutonium annihilation. Our goal was to investigate ThO2 -PuO 2 MOX in the aim to propose a suitable fuel for the existing and future CANDU units in Romania. Both weapon grade and reactor grade Plutonium were considered as fissile drivers for Thorium. Since this is only an exploratory study, some key design parameters such as fuel pellet density and ThO2 /PuO 2 ratio were considered to span over a certain range imposed by MOX fuel fabrication technology and limited Plutonium availability. Eighteen fuel compositions were considered and cell calculations were performed for 37 and 43-element bundles using several computer codes.

Pelletization of Biomass Feedstocks: Effect of Moisture Content, Particle Size and a Binder on Characteristics of Biomass Pellets

Pelletization of low value added biomass materials such as furfural residue (FR) and sawdust was performed by using a lab scale pelletizer. Effects of moisture content (MC), particle size and a binder on quality parameters (e.g. pellet density, strength and hardness) and on energy consumption were investigated. Quality of pellets was analysed and compared. MC was found to be the more dominant parameter affecting pellet density, strength and hardness of furfural residue pellets (FRPs) and sawdust pellets (SPs), followed by particle size and a binder. Highest particle density of 1.419 g/cm3 for FRPs (0.5–1.41 mm) and 1.243 g/cm3 for SPs (0.25–0.5 mm) was achieved at MC of 8% and 18%. Highest decrease in relaxed density was observed at MC of 13% for FRPs and 28% for SPs. True density of FRPs and SPs made from particles of 0.25–0.5 mm was found higher than 0.5–1.41 mm. The highest strength and hardness (6.29 MPa and 401.3 N/mm2) for FRPs was achieved at 5.5% MC and particles 0.25–0.5 mm. Optimum strength (6.03 MPa) and hardness (96.06 N/mm2) for SPs was obtained at 18% MC and particles 0.25–0.5 mm. The lowest energy consumption (16.16 J/g) for FRPs (0.25–0.5 mm) and 20.22 J/g for SPs (0.5–1.41 mm) was achieved at MC of 13% and 28%. Addition of binding agent to FR sawdust decreased energy consumption of FRPs and SPs. SPs quality was enhanced with the use of a binder. Heating value of FRPs were found higher than SPs.

Mechanical and Combustion Properties of Agglomerates of Wood of Popular Eastern European Species

The objective of the reported project was to produce wood agglomerates from popular East European species to determine their strength and combustion properties. Closed-die pellets were produced from sawdust of six types of wood common on the East European market: pine, willow, oak, poplar, birch, and beech. The properties of pellets, determined by the type of wood, were influenced by the compaction pressure and the moisture content of the sawdust. The highest average pellet density was obtained for oak sawdust, while the lowest density was obtained for poplar pellets. Expansion of pellets after removing from the die was found to be dependent on the wood species, and as expected, on compaction pressure. The pellet expansion increased after 2 h of conditioning in the laboratory and with an increase in moisture content. The highest and the smallest strength were obtained for oak pellets and for birch sawdust, respectively. The strength of the pellets increased by more than 100% with an increase in the compaction pressure from 60 MPa to 120 MPa. The average strength decreased by 65% with increasing moisture content. For all tested materials, drop resistance remained at a high level, acceptable in industrial practice. The highest calorific value of 18.97 MJ/kg was obtained for pine pellets. The highest ash value of 1.52% was obtained for willow pellets and the lowest value of 0.32% for pine pellets.

Hydroxyapatite supported molybdenum oxide catalyst for selective oxidation of methanol to formaldehyde: studies of industrial sized catalyst pellets

Promising alternative catalysts for the Formox process as industrial sized pellets and the influence of pellet density on catalyst performance.

Data-Driven Modelling of a Pelleting Process and Prediction of Pellet Physical Properties

In the manufacture of pelleted catalyst products, controlling physical properties of the pellets and limiting their variability is of critical importance. To achieve tight control over these critical quality attributes (CQAs), it is necessary to understand their relationship with the properties of the powder feed and the pelleting process parameters (PPs). This work explores the latter, using standard multivariate methods to gain a better understanding of the sources of process variability and the impact of PPs on the density and strength of the resulting pellets. A Kilian STYL’ONE EVO Compaction Simulator machine was used to produce over 1000 pellets, whose properties were measured, with varied powder feed mechanism and powder feed rate. Process data recorded by the Compaction Simulator machine were analysed using Principal Component Analysis (PCA) to understand the key aspects of variability in the process. This was followed by Partial Least Squares (PLS) regression to predict pellet density and hardness from the Compaction Simulator data. Pellet density was predicted accurately, achieving an R2 metric of 0.87 in 10-fold cross-validation, and 0.86 in an independent hold-out test. Pellet hardness proved more difficult to predict accurately, with an R2 of 0.67 in 10-fold cross-validation, and 0.63 in an independent hold-out test. This may however simply be highlighting measurement quality issues in pellet hardness data. The PLS models provided direct insights into the relationships between pelleting PPs and pellet CQAs and highlighted the potential for such models in process monitoring and control applications. Furthermore, the overall modelling process boosted understanding of the key sources of process and product variability, which can guide future efforts to improve pelleting performance.

Thermochemical Characterization of Rice Husk (Oryza Sativa Linn) for Power Generation

Rice husk is biomass that can be utilized as fuel for biomass gasification as a renewable energy source. In this paper, thermochemical methods were used to determine the higher heating values, moisture content, bulk density, pellet density, microstructure, and elemental composition of Thai Rice Husk (Oryza Sativa Linn). The heating energy was analyzed using a bomb calorimeter, which showed a higher heating value of 15.46 MJ/kg. Determination of pellet density through rice husk powder pelletization exhibited a value of 1.028 g/cm3, while moisture content was 5.017 wt%. The heating value and moisture content revealed good agreement with the literature values, indicating the potentiality of rice hush for energy generation. Scanning electron microscopy (SEM) showed that the raw rice husk and its ash have similar porosity types but different bulk structure. Elemental analysis using energy dispersive X-ray (EDX) indicated that rice husk contains O, Si, C while O and C percentages were drastically decreased during combustion. The obtained heating value and moisture content proved that rice husk could be used as a bio-energy source in biomass gasification for power generation.

Lignin: a valuable feedstock for biomass pellet

Pelletization and briquettization have been extensively used for mass and energy densification of biomass. As the demand for pellets increases, the biorefinery waste lignin can be used with the conventional raw materials for pellet preparation. Sugarcane bagasse (20-40 mesh) is treated with NaOH (8% & 16%) for bioethanol production and obtained lignin is used to prepare pellet along and with sugarcane bagasse (SB). SB, Lignin1 (8% NaOH treated SB), Lignin2 (16% NaOH treated SB) and various composition of SB and Lignin1 were used to produce pelletswith different applied pressures (5kN, 10kN, 15kN and 20kN). Pellet density and heating value were gradually increase with the applied pelletization pressure. Among the samples Lignin1 showed highest heating value at 20kN (3581.54 kcal/kg). Results revealed that 5kN is enough to produce pellet from different composition of SB and Lignin1 and the pellet composition of SB (40%) and Lignin1(60%) showed the highest heating value (3456.21 kcal/kg). Bangladesh J. Sci. Ind. Res.55(1), 83-88, 2020

Application of Multiple Linear Regression and Artificial Neural Networks for the Prediction of the Packing and Capsule Filling Performance of Coated and Plain Pellets Differing in Density and Size

Plain or coated pellets of different densities 1.45, 2.53, and 3.61 g/cc in two size ranges, small (380–550 μm) and large (700–1200 μm) (stereoscope/image analysis), were prepared according to experimental design using extrusion/spheronization. Multiple linear regression (MLR) and artificial neural networks (ANNs) were used to predict packing indices and capsule filling performance from the “apparent” pellet density (helium pycnometry). The dynamic packing of the pellets in tapped volumetric glass cylinders was evaluated using Kawakita’s parameter a and the angle of internal flow θ. The capsule filling was evaluated as maximum fill weight (CFW) and fill weight variation (FWV) using a semi-automatic machine that simulated filling with vibrating plate systems. The pellet density influenced the packing parameters a and θ as the main effect and the CFW and FWV as statistical interactions with the coating. The pellet size and coating also displayed interacting effects on CFW, FWV, and θ. After coating, both small and large pellets behaved the same, demonstrating smooth filling and a low fill weight variation. Furthermore, none of the packing indices could predict the fill weight variation for the studied pellets, suggesting that the filling and packing of capsules with free-flowing pellets is influenced by details that were not accounted for in the tapping experiments. A prediction could be made by the application of MLR and ANNs. The former gave good predictions for the bulk/tap densities, θ, CFW, and FWV (R-squared of experimental vs. theoretical data >0.951). A comparison of the fitting models showed that a feed-forward backpropagation ANN model with six hidden units was superior to MLR in generalizing ability and prediction accuracy. The simplification of the ANN via magnitude-based pruning (MBP) and optimal brain damage (OBD), showed good data fitting, and therefore the derived ANN model can be simplified while maintaining predictability. These findings emphasize the importance of pellet density in the overall capsule filling process and the necessity to implement MLR/ANN into the development of pellet capsule filling operations.

Effect of extractives on the physicochemical properties of biomass pellets: Comparison of pellets from extracted and non-extracted sycamore leaves

Physicochemical properties of biomass pellets were compared following their preparation from extracted and non-extracted sycamore leaves. The goal was to achieve high-quality biomass pellets. Batches of pellets were prepared at different moisture contents and pressure. The properties, including pellet density, diametric compressive strength, and combustion performance, were analyzed. Pellets produced from extracted leaves had higher pellet density (between 1125 and 1250 kg·m-3) compared to those made from non-extracted leaves. In addition, data of the combustion experiment showed more weight loss in extracted leaves’ pellets and a higher burning rate (9.54%·min-1) than that of non-extracted leaves’ pellets (8.47%·min-1). Also, the pellets made from extracted leaves could be ignited and burned easily compared to non-extracted leaves. However, the diametric compressive strength was not always higher in extracted leaves’ pellets compared to non-extracted. In general, it was concluded that extraction could increase the pellet density and improve combustion performance but did not fit the purpose to increase the diametric compressive strength. The analysis and conclusions can provide a reference for the production of high-quality biomass pellets.