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The present study evaluates elastic and inelastic contact forces in predicting the fluidization characteristics of irregularly shaped Titania nanoparticle agglomerates in a bench-scale conical fluidized bed. At first, experiments were performed to identify the mutual effects of gas velocity and agglomerate size on the instantaneous pressure, bed pressure drop and bed expansion ratio. Rigid complex-agglomerates (∼100−200 μm) were mainly formed in the partially fluidized regime, while soft simple-agglomerates (∼20−70 μm) were primarily formed in the spouting regime. The simulations were performed through the CFD-DEM approach. The error analysis of results in the partially fluidized regime revealed that the combination of Hertz-Mindlin and Johnson-Kendall-Roberts (HM + JKR) model led to a better prediction of the bed pressure drop and bed expansion ratio than the spring-dashpot (LSD) model. In the transition flow regime, the Hysteretic model led to better results of the instantaneous pressure values than those proposed for other flow regimes. In the spouting flow regime, the HM and Thornton models led to over-estimation of bed pressure drop when compared to the LSD model. The comparative results of this study provide promising new insights into the collision mechanism of polydisperse agglomerates in different flow regimes for industrial aspects.

Draft tubes have emerged as promising internal devices to overcome the scale up limitations of the spouted bed. Although only a few parameters define draft tubes, the design of these devices is complex and remains a challenging task, as knowledge concerning the gas–solid flow pattern in the spouted bed is required for a proper implementation. Therefore, this study aims to propose a new criterion for the design of draft tubes (nonporous and open-sided) based on the average spout diameter measured by a borescopic technique in conical spouted beds without draft tube. Based on the radial and axial particle velocity profiles, hydrodynamic analysis, and cycle time distributions, the new configurations are compared with those without tube and with conventional draft tubes. The new open-sided tube provides maximum particle velocities of 480.90 ± 14.60 mm/s in the spout and 90.10 ± 4.40 mm/s in the annulus. These values are lower and higher than the particle velocities obtained without draft tube in the spout and annulus regions, respectively, which means it modifies particle residence time in these regions. The new open-sided tube provides a more efficient gas–solid contact than any conventional one, with spouting behaviour being very similar to the configuration without tube (differences in the minimum spouting velocity being in the 2–6% range), which is a key aspect for scale up purposes.

Various drag models were implemented in a superquadric CFD-DEM code and validated for the simulation of spherical and ellipsoidal particles in spouted beds. The most suitable drag models were identified by comparing the predicted local particle velocity with those measured by particle tracking velocimetry (PTV). The model by Beetstra et al. is the one that best reproduces the experimental results for the spouting of spherical particles, whereas the one by Sanjeevi et al. is the most suitable for ellipsoidal irregular ones. Their capability for the prediction of key operating parameters was demonstrated in both conical and prismatic spouted beds, as they correctly predict the minimum spouting velocity (ums) and fountain height in different configurations (without draft tube and different draft tubes) for particles of different size and shape. The CFD-DEM model predicts the preferential orientation of ellipsoidal particles at each location in the bed and the influence of internal devices on this parameter, which is of the utmost importance in the design of reliable coating apparatuses in the pharmaceutical industry.

Drying is a highly energy-intensive process and dryers are considered one of the most energy-consuming industrial equipment. Nevertheless, the energy contribution of the draft tube in the spouted bed has hardly been studied. This equipment is widely recognized as a versatile and efficient gas-solid contact method for several chemical and physical operations. Thus, the objective of this study is to perform an energy analysis of a draft tube conical spouted bed for particulate materials. Drying of alumina, soybean, and barley has been performed with three different configurations: without tube and with nonporous and open-sided tubes. Energy Efficiency, Drying Efficiency, and Specific Energy Consumption have been the parameters considered for energy analysis. The nonporous tube provided the best energy performance for diffusive materials, such as barley and soybean particles, with reductions in the energy consumption in the range from 31.60% to 42.40% in relation to configuration without tube. The configurations with open-sided tube and without tube provided similar energy performance for all materials. Therefore, this study contributes to support that draft tubes are promising devices for improving energy issues in the spouted bed, mainly in the processing of low moisture materials.

The hydrodynamic behavior of cohesive TiO2 nanoparticle agglomerates was studied in a conical fluidized bed. The effects of size, particle polydispersity, and airflow velocity were analyzed in the transition regime from heterogeneous to homogeneous and turbulent fluidization. The simple-agglomerates size was ~25–75 μm with fractal dimensions of ~1.95–2.50. Adhesive CFD-DEM simulations were performed to study the interaction between the simple-agglomerates by combining Mindlin-Dersiewicz and Johnson-Kendall-Roberts (JKR) contact models. The effects of restitution and friction coefficients, probability density function, and coordination number of agglomerates were studied on the particle velocity profiles in the spout and annular zones. The error analysis results showed that bed dynamics is more sensitive to a change in the friction coefficient than in the restitution coefficient. A good agreement between the results was found for friction and restitution coefficients close to one, which is evidence of nearly elastic collisions between TiO2 agglomerates.

Spouted bed stability and operation is greatly affected by particle features. Accordingly, the hydrodynamic behaviour of conical spouted beds has been studied for fine particles differing in size and density in a wide range of inlet air flow rates. This knowledge is essential for a successful scaling up and industrial implementation of the spouted bed. Therefore, the effect air velocity and solid properties (density and size) have on local solid velocity has been ascertained in a fountain confined conical spouted bed using a borescope technique (Particle Tracking Velocimetry, P T V ) applied to several bed configurations. The results show a close relationship between the inlet air velocity and the local solid velocity, with the gas-solid contact being especially vigorous in the configurations without draft tube and with the open-sided draft tube. The solid circulation flow rate is lowest when a nonporous draft tube is used due to the low solid vertical velocities in the annulus, even at high air flow rates. Nevertheless, vertical velocities in the annular zone increase when particle size and density are increased, although these velocities are lower in the spout and fountain regions due to the higher momentum exchange required for their acceleration.

A novel internal device called fountain confiner has been developed, which stabilizes the system and allows operating with fine particles, even without any type of draft tube. Given the stability this device confers upon the system, lower minimum spouting velocities than in conventional systems are required, and therefore the correlations in the literature overestimate this hydrodynamic parameter. Accordingly, runs have been carried out using this novel device in order to study the hydrodynamics and the influence geometric and operating factors have on the minimum spouting velocity in fountain confined conical spouted beds, with and without draft tubes. The beds are made up of fine sand and sawdust particles. Based on an experimental design, it was ascertained that, although certain factors are influential in given configurations, those of greater influence in all the configurations are the solid properties, static bed height and gas inlet diameter. Therefore, new correlations have been proposed for predicting the minimum spouting velocity in each configuration.

Pressure fluctuation analysis has been used to identify different flow regimes in spouted beds. Although this is a promising cost-effective tool for process control and design purposes, it has hardly been used in spouted beds operating with fine and irregular particles. Therefore, the aim of this paper is to apply pressure fluctuation analysis to spouted beds operating with fine and irregular particles, either without tube or equipped with draft tube. The minimum spouting velocities estimated by the spectral analysis in systems without tubes differ from those obtained based on the characteristic curves in the range from 10.60% (sand) to 3.50% (glass beads). Thus, the main novelty of this study lies in the application of pressure fluctuation and spectral analyses in spouted beds operating with fine and irregular particles by considering the influence of the internal devices. Therefore, the methodology proposed based on both hydrodynamic and spectral analyses is a feasible and promising alternative for delimiting the minimum spouting velocity and stable operating conditions in industrial processes, especially when the aim is process control and scaling up.

This study examined elutriation, attrition, and segregation in a conical spouted bed with a fountain confiner and incorporating an open sided draft tube. Fine silica sand with a wide particle size distribution was employed as a model material, operating in both the batch and continuous modes. The use of a fountain confiner is crucial when operating with fine particles, because otherwise the bed rapidly exhibits significant entrainment. The extent of attrition was quantified using a tracing technique based on differently-coloured sand fractions as well as monitoring size distributions by sieving. Particle breakage was found to be the primary attrition mechanism, and the fountain confiner was determined to limit the elutriation of fine particles resulting from breakage. Consequently, only a small fraction of the finest particles were entrained from the bed. The incorporation of a confiner increased operational stability while reducing segregation, especially in the upper half of the bed where the majority of segregation typically occurs. Thus, the bed was perfectly mixed apart from very minimal segregation close to the wall and at the bottom of the contactor. These results provide a basis for the design and operation of larger scale equipment for the continuous drying of materials.

The effect the solid inlet design has on the continuous drying of sand in a conical spouted bed has been studied. Five designs have been tried, four feeding the solid from the top and the fifth one...

The catalytic cracking of 2-methoxy-4-methylphenol (MMP) and of a mixture of this compound (20 wt%) with n-hexadecane (C16) has been conducted in a CREC Riser Simulator Reactor at 400-550 °C using ...

The flow and mixing behavior of two miscible liquids has been studied in an innovative static mixer by using CFD, with Reynolds numbers ranging from 20 to 160. The performance of the new mixer is compared with those of Kenics, SMX, and Komax static mixers. The pressure drop ratio (Z-factor), coefficient of variation (CoV), and extensional efficiency (α) features have been used to evaluate power consumption, distributive mixing, and dispersive mixing performances, respectively, in all mixers. The model is firstly validated based on experimental data measured for the pressure drop ratio and the coefficient of variation. CFD results are consistent with measured data and those obtained by available correlations in the literature. The new mixer shows a superior mixing performance compared to the other mixers.

[EN] A study was carried out on the valorization of different waste plastics (HDPE, PP, PS and PE), their mixtures and biomass/HDPE mixtures by means of pyrolysis and in line oxidative steam reforming. A thermodynamic equilibrium simulation was used for determining steam reforming data, whereas previous experimental results were considered for setting the pyrolysis volatile stream composition. The adequacy of this simulation tool was validated using experimental results obtained in the pyrolysis and in line steam reforming of different plastics. The effect the most relevant process conditions, i.e., temperature, steam/plastic ratio and equivalence ratio, have on H-2 production and reaction enthalpy was evaluated. Moreover, the most suitable conditions for the oxidative steam reforming of plastics of different nature and their mixtures were determined. The results obtained are evidence of the potential interest of this novel valorization route, as H-2 productions of up to 25 wt% were obtained operating under autothermal conditions. This work was carried out with the financial support from Spain's ministries of Science, Innovation and Universities (RTI2018-098283-JI00 (MCIU/AEI/FEDER, UE)) and Science and Innovation (PID2019-107357RB-I00 (MCI/AEI/FEDER, UE)), the European Union's Horizon 2020 research and innovation programme under the Marie SklodowskaCurie grant agreement No. 823745, and the Basque Government (IT1218-19 and KK-2020/00107).

Bed symmetry has been analysed in fountain confined conical spouted beds operating with fine particles. Thus, vertical particle velocities and the spout shape have been determined in a wide range of spouting air velocities and bed configurations. Bed symmetry is widely accepted in the spouted beds without draft tubes or with nonporous ones, but this is not the case when open-sided draft tubes are used. Thus, radial particle velocity profiles differ depending on the cross-sectional angular plane considered in the open-sided draft tubes. The spout expands preferentially along the tube opened surface, and is wider as spouting air velocity and aperture ratio are increased. The literature correlations proposed for the average spout diameter have been analysed and no one is valid for estimating this parameter in the whole range of spouting air velocities and configurations analysed in these systems operating with fine particles. This work has received funding from Spain's Ministry of Science and Innovation (PID2019-107357RB-I00 (AEI/FEDER, UE)), the Basque Gov- ernment (IT1218–19 and KK-2020/00107) and the European Commis- sion (HORIZON H2020-MSCA RISE-2018. Contract No.: 823745). M. Tellabide thanks Spain's Ministry of Education, Culture and Sport for his Ph.D. grant (FPU14/05814). I. Estiati thanks the University of the Basque Country for her postgraduate grant (ESPDOC18/14).

[EN] The steam pyrolysis of pinewood sawdust has been conducted in a bench scale plant provided with a conical spouted bed reactor (CSBR). This process is of uttermost relevance for the in-line valorisation of pyrolysis volatiles, specifically for their catalytic steam reforming for hydrogen production. The influence of temperature on the product yields has been analyzed in the 500-800 degrees C range. A detailed analysis of the volatile stream (condensable and non-condensable components) has been carried out by chromatographic techniques, and the char samples have been characterized by ultimate and proximate analyses, N-2 adsorption-desorption, and Scanning Electron Microscopy. A high bio-oil yield was obtained at 500 degrees C (75.4 wt%), which is evidence of the suitable features of the conical spouted bed reactor for this process. As temperature was increased, higher gas and lower liquid and char yields were obtained. Steam was fully inert at low pyrolysis temperatures (500-600 degrees C), and only had a little influence at 700 degrees C due to the low gas residence time in the conical spouted bed reactor. At 800 degrees C, the reaction mechanism was controlled by gasification reactions. The composition of the liquid fraction was considerably influenced by pyrolysis temperature, with a less oxygenated stream as temperature was increased. Thus, phenolic compounds accounted for the major fraction at low pyrolysis temperatures, whereas hydrocarbons prevailed at 800 degrees C. The char obtained in the whole temperature range can be further used as active carbon or energy source. This work was carried out with the financial support from Spain's ministries of Science, Innovation and Universities (RTI2018-101678-B-I0 0 (MCIU/AEI/FEDER, UE) and RTI2018-098283-J-I0 0 (MCIU/AEI/FEDER, UE) ) and Science and Innovation (PID2019-107357RB-I0 0 (AEI/FEDER, UE) ) and the Basque Government (IT1218-19 and KK-2020/00107) . Moreover, this project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 823745.

The 3A zeolites are excellent adsorbents for industrial-scale gas dehydration because of the low energy required for regeneration and ease of operation. A computational study of the dehydration of an industrial feed stream containing ethane and water was performed using an in-house code that included an appropriate equilibrium adsorption isotherm. The validated computational model was used to examine the impact of particle size on the process dynamics and the corresponding pressure drop. The water concentration along the adsorption column was also investigated. To increase the process capacity, the packed adsorption bed was divided into two distinct layers, which were operated with different particle sizes. The length of each layer was determined by a parametric study. The best breakthrough time, i.e., 107,800 s, at the allowed pressure drop was obtained when the lengths of the first and second layers were 4.5 and 1 m, respectively. The results showed that the new two-layer adsorption bed could save around 33.8% in total energy requirement in comparison to that of a single bed.

The drying of fine sand particles (below 1 mm) has been studied in a conical spouted bed fitted with a draft tube in order to ascertain the performance of a new internal device to confine the fountain. Accordingly, batch runs have been carried out using three types of draft tubes, with confiner and without it under ambient conditions. Their performances have been compared in order to ascertain the optimum configuration. The results evidence that the systems with the confiner perform much better than those without it. Thus, the drying time decreases considerably and the pressure drop and air flow rate decrease slightly when the confiner is used. The drying performance of the open-sided draft tube is superior to any other configuration, i.e., the drying time required with this tube is the shortest. Nonporous draft tubes are the worst option due to their poor gas-solid contact. Porous draft tubes have an intermediate performance.

Degradation behavior and kinetics of microalgae chlorella vulgaris, wood, scrap tire and binary and ternary mixtures were investigated by using thermogravimetry analysis method. Experiments were carried out at different heating rates of 10 − 20 and 40 ° C / min from ambient temperature to 600 °C. The results showed that decomposition of microalgae, wood and tire take place in three stages and the second stage is the main thermal decomposition step. Besides, heating rate enhancements shift the maximum peak temperature of microalgae, wood and scrap tire from 300 °C, 350 °C and 380 °C to 340 °C, 390 °C and 420 °C, respectively. In the case of the ternary mixture, the maximum peak temperature of the mixture was approximately equal to the maximum peak temperature of the tire. The interaction between materials was studied and the results showed that the interaction is inhibitive rather than synergistic. The results of kinetic investigation showed that the tire and the wood have the highest (273.64 kJ/mol) and the lowest (120.96 kJ/mol) activation energy, respectively. The presence of wood and microalgae increased the total weight loss of binary mixture of microalgae-tire and wood-tire, while tire presence did not improve the degradation of microalgae-wood mixture.

A methodology based on the borescopic technique has been developed and validated for tracking solid movement within a conical spouted bed. The procedure developed and fine-tuned allows monitoring the descending and ascending optical flow of both spherical and irregular particles in the annulus (dense zone) and spout (dilute zone) in the bed. A high speed camera (up to 16,000 fps) fitted with a fiber optic continuous light source was used for recording, and an image treatment algorithm modified and adapted to account for differences in particle shape and bed density (dilute or dense) was applied to the registered data. The procedure allows gathering information on the velocity of particles in a wide range of sizes, from a few millimeters ( d p ¯ = 7 mm) to micrometers ( d p ¯ = 93 μm).

The performances of the primary catalysts olivine, dolomite, γ-alumina and FCC spent catalyst were evaluated in the continuous steam gasification of sawdust in a bench-scale plant equipped with a fountain confined conical spouted bed reactor. The experiments were carried out at 850 °C, and the efficiency of the gasification process was defined by gas yield, H2 production, tar concentration and composition, and carbon conversion efficiency. The benefits of the fountain confiner not only helped to improve the gas-solid contact, and therefore favoured the primary catalysts’ reforming and cracking activity, but also enhanced H2 production and reduce tar formation. Thus, dolomite and γ-alumina recorded the lowest values of tar, 5.0 and 6.7 g Nm−3, respectively, which corresponded to 79% and 72% tar reduction compared to the inert sand, whereas olivine and the FCC spent catalyst recorded higher tar contents, 20.6 and 16.2 g Nm−3, respectively. It is noteworthy that light PAHs were the most abundant species in the tar (60 wt% of the whole tar content).

A study has been carried out on the influence process conditions and design parameters have on the drying in a conical spouted bed. Optimum parameters have been determined for the draft tub...

A novel strategy has been proposed for the rigorous kinetic modeling of tyre pyrolysis in a conical spouted bed reactor. A kinetic model coupled with a gas flow model was used in the fitting of experimental results obtained in a bench scale unit in the 425–610 °C range. A gas flow model should be incorporated to account for the delay and mixing phenomena observed in tracer experiments, as these phenomena cause remarkable deviations in the assessment of the kinetic parameters. The gas flow pattern from the reactor to the measuring device was modeled using two different approaches based on ideal flow reactors. Furthermore, two kinetic schemes considering lumped products have been proposed; the first one is based on four parallel independent reactions accounting for the volatile products (gas, liquid, aromatics and tar). The second one considers an additional secondary reaction of aromatic formation from the liquid. The strategy proposed for coupling the kinetics and the flow model led to a suitable fitting of the experimental results, with the performance of the model considering a secondary reaction being slightly better than the simple one.

The performance and stability of different Ni supported catalysts have been studied in a continuous bench scale plant fitted with a conical spouted bed reactor for biomass pyrolysis at 500 °C and a fluidized bed reactor for the in line catalytic steam reforming of pyrolysis volatiles at 600 °C. The metal oxides selected as Ni supports have been Al2O3, SiO2, MgO, TiO2 and ZrO2, and all the catalysts have been prepared by the wet impregnation method. Significant differences have been observed in the performance and stability of the catalysts, with the most suitable ones concerning the evolution of bio-oil oxygenate conversion and H2 yield with time on stream being as follows: Ni/Al2O3 > Ni/ZrO2 > Ni/MgO > Ni/TiO2 > Ni/SiO2. The activity and stability are explained based on the properties of the catalysts, which have been measured prior and after their use, by means of different techniques: N2 adsorption/ desorption, X-ray fluorescence (XRF), X-ray powder diffraction (XRD), temperature programmed oxidation (TPO), in-line monitoring by Fourier-transform infrared spectroscopy-temperature programmed oxidation (FTIR-TPO), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

The rising repair and maintenance costs of road and airstrip pavements subjected to frequent and repeated traffic loading is a major impetus for researches to delve into the use of additives and admixtures in the asphalt mixture production. The primary goal of these efforts is to improve the durability and load-bearing performance of asphalt mixtures. Due to favorable properties, such as high stiffness, all-around fracture, and high internal friction angle, crushed glass may be used as a high-potential additive for improving asphalt mixtures’ quality. Despite the many advantages of crushed glass, the inadequate adhesion between bitumen and glass particles can lead to stripping and reduced strength of glass-containing asphalt mixtures (glass-asphalt). In this study, glass particles were used, as aggregates in warm mix asphalt (WMA) mixtures. Four different amounts of zycothermTM were used in WMA mixtures to serve as bitumen modifier and anti-stripping agent. The performance properties of the pure bitumen and the zycothermTM-modified bitumen were evaluated through Scanning Electron Microscopy (SEM), Fourier Transform Infrared spectroscopy and bitumen tests. The WMA specimens and control specimens were also subjected to the modified Lottman test, resilient modulus test, and creep test. The results showed that use of zycothermTM as an anti-stripping agent considerably improves the performance properties and moisture sensitivity of glass-asphalt.

Many applications of the conical spouted beds involve operations using coarse and fine particle mixtures, which require high gas velocities due to the coarse particles, thereby leading to fine particle entrainment. In order to avoid entrainment, a new device has been proposed to confine the fountain. Thus, a study has been conducted on the influence the geometry and configuration of both confiner and draft tube have on particle entrainment, operating pressure drop, operating air flow rate and maximum cycle time. The results show that the fountain confiner greatly stabilises the operation and significantly reduces (above 50%) particle entrainment, but its influence on the other parameters is of rather low significance. Furthermore, the distance between the lower end of the device and the bed surface has a great impact on the performance of the spouted bed regime. Entrainment monitoring throughout time showed that its rate depends on the configuration, but remains constant with time.

Pinewood sawdust and the waste rubber from truck tyres have been co-pyrolysed in order to improve the properties of bio-oil for its integration in oil refineries. In addition, an analysis has been conducted of the effect the interactions between these two materials’ pyrolysis reactions have on product yields and properties. Biomass/tyre mixing ratios of 100/0, 75/25, 50/50, 25/75 and 0/100 by weight percentage have been pyrolysed in continuous mode at 500 °C in a conical spouted bed reactor, obtaining oil yields in the 55.2–71.6 wt% range. Gaseous, oil and solid fractions have been characterised for the 50/50 biomass/tyre mixture, paying special attention to the oil fraction by determining its detailed composition, elemental analysis and calorific value. Co-processing enables the stabilization of the liquid, as the co-pyrolysis oil has a stable single phase, being composed mainly of water, aromatic hydrocarbons and phenols in concentrations of 14.5, 11.1 and 9.7 wt%, respectively. Adding tyre rubber to the biomass in the pyrolysis feed improves the oil’s properties, as a liquid with higher carbon content and lower oxygen and water is obtained, even if sulphur content is also increased.

A study was carried out on the effect the evolution of the porous structure and metal content have on the gasification rate during char gasification in a conical spouted bed reactor. Partially gasified samples at different temperatures (800–900 °C range) were collected at various conversion levels and characterized by different techniques (N 2 adsorption-desorption, ultimate/proximate analysis and X-ray Fluorescence). At 900 °C there is a fast development of the porous structure, attaining the highest BET specific surface area (S BET ) (633 m 2 g −1 ) at low conversion. Char reactivity profiles revealed that the development of the porous structure influenced the reaction rate mainly at early stages, whereas the increase in the gasification rate for conversions higher than 60% (especially at 900 °C) was attributed to the catalytic effect of Ca, K and Fe (the main metals in the ashes).

A study was carried out to understand the influence of calcination conditions of a Ni/MgO–Al2O3 catalyst on its performance and stability in the reforming of biomass fast pyrolysis volatiles. Accordingly, the first calcination temperature subsequent to promoter impregnation on Al2O3 was modified from 900 to 700 °C. Subsequently, Ni was incorporated by impregnation and a second calcination was carried out at three temperatures (500, 600, and 700 °C). The performance of the different Ni/MgO–Al2O3 catalysts was evaluated in a bench-scale plant operating in the continuous regime, which comprised a conical spouted bed reactor for the pyrolysis step and a fluidized bed reactor for the in-line catalytic steam reforming step. The fresh catalyst was also characterized in order to establish the relationship between the catalyst properties and calcination temperatures at the synthesis step. Moreover, the deactivated catalysts were comprehensively characterized in order to ascertain the main causes of activity decay in the catalysts. Therefore, the catalyst calcined at the lowest temperature subsequent to both the impregnation steps (Ni500/MgO700Al2O3) exhibited the best performance at the reforming step, as the amount of spinel phase formed is lower, and therefore, the catalyst reducibility is increased, leading to higher reforming activity and stability with respect to time on stream.

A study has been carried out of the regenerability of a commercial Ni catalyst used in the steam reforming of the volatiles from biomass pyrolysis (gases and bio-oil), determining the evolution of the reaction indices (conversion, product yields and H2 production) in successive reaction–regeneration cycles. The causes of catalyst deactivation (coke deposition and Ni sintering) have been ascertained characterizing the deactivated and regenerated catalysts by TPO, TEM, TPR and XRD. Catalyst activity is not fully recovered by coke combustion in the first cycles due to the irreversible deactivation by Ni sintering, but the catalyst reaches a pseudo-stable state beyond the fourth cycle, reproducing its behaviour in subsequent cycles.

Continuous catalytic cracking of polyethylene over a spent fluid catalytic cracking (FCC) catalyst was studied in a conical spouted bed reactor (CSBR) with fountain confiner and draft tube. The effect of temperature (475–600 °C) and space‐time (7–45 gcat min gHDPE −1) on product distribution was analyzed. The CSBR allows operating with continuous plastic feed without defluidization problems and is especially suitable for catalytic pyrolysis with high catalyst efficiency. Thus, high catalyst activity was observed, with waxes yield being negligible above 550 °C. The main product fraction obtained in the catalytic cracking was made up of C5−C11 hydrocarbons, with olefins being the main components. However, its yield decreased as temperature and residence time were increased, which was due to reactions involving cracking, hydrogen transfer, cyclization, and aromatization, leading to light hydrocarbons, paraffins, and aromatics. The proposed strategy is of great environmental relevance, as plastics are recycled using an industrial waste (spent FCC catalyst)., One man's trash: The use of FCC spent catalyst in a fountain confined spouted bed reactor demonstrates great potential for plastics valorization. A complete polymer conversion towards valuable products as light olefins and gasoline‐range hydrocarbons is obtained. This strategy is of great environmental interest as plastics are recycled using a waste catalyst.

[EN]The activity and stability of a 10 wt%NiO/CaO catalyst were tested in the sorption enhanced ethanol steam reforming (SEESR) in a fluidized bed reactor. The effect of temperature in the 600-750 degrees C range was analyzed and the performance of the catalyst at 700 degrees C was assessed by conducting cycles of SEESR reaction and CO2 desorption. At zero time on stream, an increase in temperature enhanced ethanol steam reforming reactions, and therefore H-2 production increased from a yield of 20.3 wt% at 600 degrees C to 22 wt% at 750 degrees C. However, high temperatures hindered the catalyst sorption performance, i.e., CO2 capture declined from 7.9 to 2.1 mmol(CO2) g(cat)(-1). In order to evaluate the catalyst performance throughout the cycles and relate it with its features, both fresh and deactivated catalysts were characterized in detail by N-2 adsorption-desorption, X-ray fluorescence (XRF), X-ray diffraction (XRD), temperature programmed reduction (TPR) and oxidation (TPO) and transmission electron microscopy (TEM). Subsequent to 12 cycles, the catalyst CO2 capture performance was slightly lower than that of the fresh one (approximately 7%) and hardly changed in the next cycles. Furthermore, the use of the same temperature for SEESR reaction and CO2 desorption led to the highest adsorption capacity of the catalyst over multiple cycles. This work was carried out with financial support from the Spain's Ministries of Science, Innovation and Universities (RTI2018-098283-J-I00 (MCIU/AEI/FEDER, UE) and (RTI2018-101678-BI00 MCIU/AEI/FEDER, UE) and Science and Innovation (PID2019-107357RB-I00 (MCI/AEI/FEDER, UE) , the Basque Government (IT1218-19 and KK-2020/00107) . This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 823745. Maria Cortazar also thanks the Basque Government for her research training grant.

The environmental problems related with the management of waste plastics require the development of efficient valorization routes. This chapter deals with three different strategies aimed at the selective conversion of plastics to chemicals and hydrogen following the two-step continuous processes. Flash pyrolysis performed in a conical spouted bed reactor is the first step in the three alternatives, whereas the options proposed for the second step are as follows: 1) non-catalytic cracking in a multitubular reactor for the production of light olefins, 2) catalytic cracking on a HZSM-5 zeolite in a fixed bed for light olefin production, and, 3) steam reforming in a fluidized bed reactor on a Ni-based catalyst for hydrogen production. The three strategies allow full conversion of wax (main pyrolysis product) with high selectivity to different products. Thus, the cracking processes lead to high olefin yields in the 62-77 wt% range, whereas reforming allows a hydrogen production of 38 wt%.

[EN] The performance of both fluidized and spouted bed reactors in the pyrolysis of waste plastics is conditioned by particle agglomeration phenomena, which worsen the quality of the gas-solid contact and eventually lead to defluidization. The objective of this work is to determine the optimum conditions for stable operation (without defluidization) in a bench scale plant fitted with a fountain confined conical spouted bed reactor and equipped with a nonporous draft tube, which operates in continuous mode. The insertion of these devices enhances the gas-solid contact, especially in the fountain region, and leads to a highly stable hydrodynamic regime, with these features being of especial relevance for the in situ catalytic pyrolysis of waste plastics. This paper deals with the effect different variables have on the minimum temperature for stable operation by avoiding defluidization. The variables analyzed are as follows: plastic type (HDPE, LDPE, PP, PS, PET and PMMA), plastic feed rate, mass of inert material in the bed, spouting velocity and use of catalyst. The results show that polymers whose chains decompose at low temperatures or have high degrees of branching require low operating temperatures. Besides, as the ratio of bed mass to plastic feed rate (Wbed/Qplastic) and/or spouting velocity were increased, the temperature required to avoid defluidization was also reduced. The use of a catalyst also reduced the temperature required for stable operation, as the activation energy of cracking reactions is greatly reduced, and so reaction rate is increased. This work was carried out with financial support from the Spain’s Ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE)), Science, Innovation and Universities (RTI2018-098283-J-I00 (MINECO/FEDER, UE)) and Science and Innovation (PID2019-107357RB-I00 (AEI/FEDER, UE), the European Commission (HORIZON H2020-MSCA RISE-2018. Contract No. 823745) .and the Basque Government (IT1218-19 and KK-2020/00107).

Small diameter hydrocyclones, or micro-hydrocyclones (below 100 mm), are commonly used in the industry due to their ability to achieve cut sizes lower than 40 μm. In order to know this cut sizes, the analysis of the particle size of the hydrocyclone streams is required. There are different techniques to obtain this information, like sieving, laser diffraction, sedimentation or microscopy. The work presented is part of one of the stages of an R&D project performed between the CPWV research group of the Chemical Engineering Department of the UPV/EHU and NOVATTIA DESARROLLOS Ltd. with the objective of achieving a more flexible, compact, and efficient hydrocyclone technology than the actual one. The goal of the study was to test the influence of the technique used to analyze the particle size of the streams on the cut size of the micro-hydrocyclone. The equipment employed to measure the particle size were Mastersizer 2000 (laser diffraction) and Sedigraph III (sedimentation). The results showed that there is a great influence of the analysis technique on the cut size.

[EN] A 2D Euler-Euler multiphase computational fluid dynamics (CFD) model in conjunction with the kinetic theory of granular flow (KTGF) was applied to describe the biomass pyrolysis in a spouted bed reactor. The primary interest in this work was the development of a CFD hydrodynamic model of the reactor coupled with a pyrolysis kinetic model for the prediction of biomass pyrolysis product yields (gas, bio-oil, and char). The kinetic model is based on three parallel reactions for the formation of the pyrolysis products and a secondary reaction of gas formation from bio-oil. The CFD hydrodynamic model suitably predicts the behavior of the spouting regime, and its simultaneous resolution with the kinetic model leads to a satisfactory quantitative agreement between the predicted and experimental values for bio-oil and gas yields. This study is evidence of the great potential of CFD techniques for the design, optimization, and scale-up of conical spouted bed reactors. This work was carried out with the financial supports from Iran’s Ministry of Science, Research and Technology accompanied by Spain’s ministries of Science, Innovation, and Universities (RTI2018-098283-J-I00 (MCIU/AEI/FEDER, UE)) and Science and Innovation PID2019-107357RB-I00 (MCI/AEI/FEDER, UE)), the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 823745, and the Basque Government (IT1218-19 and KK-2020/00107).

[EN] The performance of fixed and fluidized bed reactors in the steam reforming of biomass fast pyrolysis volatiles was compared, with especial attention paying to the differences observed in catalysts deactivation. The experiments were carried out in continuous regime in a bench scale unit provided with a conical spouted bed for the pyrolysis step. They were carried out on a Ni-Ca/Al2O3 commercial catalyst and under optimum conditions determined in previous studies, i.e., pyrolysis temperature 500 ºC, reforming temperature 600 ºC and a steam/biomass ratio of 4. Moreover, the influence of space time was analysed in both reforming reactors. The fixed bed reactor showed higher initial conversion and H2 yield, as it allowed attaining a H2 yield higher than 90 % with a space time of 10 gcat min gvol-1. However, a space time of 15 gcat min gvol-1 was required in the fluidized bed to obtain a similar H2 yield. Moreover, the fixed bed also led to lower catalyst deactivation. Catalyst deactivation was mainly related to coke deposition, and higher coke contents were observed in the catalysts used in the fluidized bed reactor (1.2 mgCOKE gcat-1 gbiomass-1) than those in the fixed bed one (0.6 mgCOKE gcat-1 gbiomass-1). Therefore, the differences in the performance of the two reactors were analysed and their practical interest was discussed. This work was carried out with the financial support fromSpain’s ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE) and Science, Innovation and Universities (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)), the EuropeanUnion’s Horizon 2020 research and innovation programme underthe Marie Skłodowska-Curie grant agreement No. 823745, and theBasque Government (IT1218-19 and KK-2020/00107).

[EN] The influence of the metal selected as catalytic active phase in the two-step biomass pyrolysis-catalytic reforming strategy has been analyzed. The pyrolysis step was carried out in a conical spouted bed reactor at 500 ºC, whereas steam reforming was performed in a fluidized bed reactor at 600 ºC. Ni/Al2O3, Co/Al2O3 and two bimetallic Ni-Co/Al2O3 catalysts with different metal loadings were synthesized by wet impregnation method, and fresh and deactivated catalysts were characterized by N2 adsorption/desorption, X-ray Fluorescence (XRF), Temperature Programmed Reduction (TPR), X-Ray powder Diffraction (XRD), Temperature Programmed Oxidation (TPO), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Although Ni/Al2O3 and both bimetallic catalysts had similar initial activity in terms of (oxygenate conversion, (higher than 98%), the poorer metal dispersion observed in both bimetallic catalysts led to a fast decrease in conversion due to the promotion of coke formation on large particles. This occurred even though Ni-Co alloy formation has a positive influence by hindering the oxidation of Co0 species. The main cause for the deactivation of these catalysts is the formation of a coke with amorphous structure. The poor initial performance of Co/Al2O3 catalyst is related to changes in the Co0 oxidation state induced by the presence of steam, which led to a fast deactivation of this catalyst. This work was carried out with the financial support from Spain’s ministries of Economy and Competitiveness (CTQ2016-75535-R (AEI/FEDER, UE) and Science, Innovation and Universities (RTI2018-101678-B-I00 (MCIU/AEI/FEDER, UE)), Science and Innovation (PID2019-107357RB-I00), the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 823745, and the Basque Government (IT1218-19 and KK-2020/00107).

The activity and stability of a Ni/ZrO2 catalyst have been studied in a continuous bench scale plant, in which biomass has been pyrolysed at 500 °C in a conical spouted bed reactor and the outlet volatile stream has been subjected to catalytic steam reforming at 600 °C in a fluidized bed reactor. The influence of space time has been analyzed, and both the fresh and the deactivated catalysts have been characterized by means of different techniques: N2 adsorption-desorption, X-ray fluorescence (XRF), X-ray powder diffraction (XRD), temperature programmed oxidation (TPO), and transmission electron microscopy (TEM). The aim of this characterization is to relate catalyst performance to the evolution of the properties from the fresh to the deactivated catalysts. Thus, an increase in space time leads to an improvement in the stability of the catalyst extending its operation period from 20 to 100 min on stream, with a maximum H2 yield of 92.4% (referred to the maximum allowed by stoichiometry) when a space time of 20 gcat min gvolatiles−1 has been used. Although the ZrO2 support has suitable properties, coke deposition is the main cause of catalyst deactivation.

The valorization of biomass (pine wood) for hydrogen production has been studied in a two-step process, comprising pyrolysis and subsequent steam reforming of the volatiles produced in the first step. This work focuses on the deactivation of the Ni commercial catalyst used in the second step. Pyrolysis of biomass has been performed in a conical spouted bed reactor at 500 °C, and the in-line catalytic steam reforming of the pyrolysis volatiles, in a fluidized bed reactor at 600 °C. Deactivated catalyst samples were recovered at different values of time on stream, and analyzed by means of XRD, N2 adsorption-desorption, SEM and TEM microscopies, TPO, Raman and FTIR spectroscopies. The results show that the deactivation is mainly due to the encapsulation of Ni particles by coke, together with Ni sintering, to a lesser extent (from a Ni particle size of 25 nm in the reduced fresh catalyst, to 39 nm at 100 min). The former is ascribed to the condensation of oxygenates (particularly phenols), and the latter is inevitable within the current conditions. As the fraction of uncovered Ni particles decreases with time on stream, the deposition of encapsulating coke is slowed down (from a formation rate of 0.30 mgcoke gcatalyst−1 min−1 to 0.20 mgcoke gcatalyst−1 min−1, at 0–50 min and 50–100 min on stream, respectively), promoting the deposition of coke on the catalyst support (with a formation rate of 1.04 mgcoke gcatalyst−1 min−1 at 50–100 min on stream), with a more carbonized structure and formed through the thermal decomposition of phenols in the reaction medium.

The steam gasification of sawdust was carried out in a bench scale plant fitted with a fountain confined conical spouted bed reactor and a nonporous draft tube, and using olivine as primary catalyst. The effect temperature (in the 800–900 °C range) had on product distribution (gas, tar and char) and composition was studied. Not only did temperature have a positive effect on the gas yield and carbon conversion, but it also played a crucial role in tar removal, as its concentration fell from 49.2 g Nm−3 (on a dry basis) at 800 °C to 6.7 g Nm−3 operating at 900 °C. Moreover, temperature also enhanced the hydrogen yield of the gas, recording a value of 7.28 wt% at 900 °C. Regarding tar formation and its evolution pathway, as gasification temperature was increased the tar composition (analyzed by GC/MS, FTIR and simulated distillation techniques) evolved to more stable aromatic compounds (of higher molecular weight), such as naphthalene or fluoranthene, with heterocyclic or light aromatic compounds being almost absent at 900 °C.

Road quality is one of the most important factors concerning the safety of transportation. Adequate skid resistance of a road surface allows drivers to maintain effective control on their vehicles and maneuver when necessary to avoid accidents. Using waste glass in asphalt mixtures is advantageous from the point of technical, environmental and economic perspectives. This study focuses on the topic of asphalt containing crushed glass, also known as glasphalt, by evaluating the skid resistance and moisture sensitivity of these mixtures. Therefore, a laboratory method was used, in which two types of continuous gradation of hot mix asphalt were chosen based on the Iranian highway asphalt paving code (Code No. 234). The fine aggregates, up to 15% of the total aggregate content, were replaced with glass particles in three different gradations. Skid resistance was evaluated in a British pendulum tester, moisture sensitivity by modified Lottman test, and resilient modulus in a UTM machine. Specimens with a moisture sensitivity problem were improved by using zycotherm as an anti-stripping agent. It was found that the crushed glass particles improved skid resistance by up to 20%. The moisture sensitivity test showed that some glasphalts were susceptible to stripping issue, which can be solved by using 0.1% zycotherm in terms of bitumen weight. Finally, findings revealed that glass particles improved resilient modulus of specimens.

The influence the support has on the performance of Ni catalysts used in the reforming of biomass fast pyrolysis volatiles has been assessed. Accordingly, five catalysts have been prepared by wet impregnation method, namely Ni/Al2O3, Ni/SiO2, Ni/MgO, Ni/TiO2 and Ni/ZrO2. These catalysts have been characterized by nitrogen adsorption/desorption, X-ray fluorescence spectroscopy, temperature programmed reduction and X-ray diffraction techniques. The pyrolysis-reforming runs have been performed in a bench scale unit operating in continuous regime. The biomass (pine wood sawdust) pyrolysis step has been carried out in a conical spouted bed reactor at 500 °C, with the volatiles produced (a mixture of gases and bio-oil) being reformed in-line on the prepared catalysts in a fluidized bed reactor at 600 °C. Remarkable differences have been observed amongst the catalyst prepared, with Ni/Al2O3, Ni/MgO and Ni/ZrO2 being those leading to the most encouraging results, whereas Ni/TiO2 and, especially Ni/SiO2, having a limited reforming activity. The performance of each catalyst has been related to its properties determined in the characterization.

An original kinetic model has been proposed for the reforming of the volatiles derived from biomass fast pyrolysis over a commercial Ni/Al2O3 catalyst. The pyrolysis-reforming strategy consists of two in-line steps. The pyrolysis step is performed in a conical spouted bed reactor (CSBR) at 500 °C, and the catalytic steam reforming of the volatiles has been carried out in-line in a fluidized bed reactor. The reforming conditions are as follows: 600, 650 and 700 °C; catalyst mass, 0, 1.6, 3.1, 6.3, 9.4 and 12.5 g; steam/biomass ratio, 4, and; time on stream, up to 120 min. The integration of the kinetic equations has been carried out using a code developed in Matlab. The reaction scheme takes into account the individual steps of steam reforming of bio-oil oxygenated compounds, CH4 and C2-C4 hydrocarbons, and the WGS reaction. Moreover, a kinetic equation for deactivation has been derived, in which the bio-oil oxygenated compounds have been considered as the main coke precursors. The kinetic model allows quantifying the effect reforming conditions (temperature, catalyst mass and time on stream) have on product distribution.

The fast pyrolysis of the juice squeezing derived orange waste has been carried out in a continuous pyrolysis bench-scale plant consisting of a conical spouted bed reactor (CSBR). A prior study performed in thermobalance and a kinetic model consisting of a multi-component mechanism allowed determining the contents of pectin (35 wt%), hemicellulose (16.6 wt%) and cellulose (17.1 wt%), but that of lignin could not be satisfactorily determined as its degradation curve overlapped with other compounds such as sugars, proteins and fats. In the bench scale experiments, the bio-oil yields were very high in the 425–500 °C range (close to 55 wt%) due to the suitable features of the CSBR (high heat and mass transfer rates and short residence time of the volatiles), but they are lower for higher temperatures due to the promotion of secondary cracking reactions. Compared to lignocellulosic biomasses, the orange waste produced a bio-oil with more methanol and furfural and less phenolic species, which is an encouraging fact for its stability and valorization by catalytic cracking or steam reforming. The high concentration of CO2 in the gas is a drawback for use for energy production. The char yield (33–27 wt%) was high in the whole range of temperatures studied and its high carbon content (71–73 wt%) and HHV (≈27 MJ kg−1) are suitable for use as fuel.

A study was carried out on the advantages of inserting a fountain confiner in conical spouted beds for biomass steam gasification and the results (gas yield and composition, tar content, carbon conversion efficiency and H2 production) are compared with those obtained under conventional spouting regime. The experiments were carried out in a bench scale unit operating in continuous regime under the same gasification conditions in all the configurations (850 °C, S/B ratio of 2 and olivine as primary catalyst). The gaseous product was analyzed by on-line gas chromatography and micro-gas chromatography, and the tars by gas chromatography-mass spectrometry. The use of a fountain confiner allows enhancing process versatility, increasing gas velocity over the minimum spouting one, increasing the fountain height and reducing olivine particle size (enhanced fountain regime). Thus, as a result of a better gas-solid contact, tar content was reduced from 49.2 g Nm−3 without fountain confiner to 20.6 g Nm−3 under enhanced fountain regime, with the reduction of heavy PAHs being especially remarkable. In the same line, a great improvement in process conversion efficiency was attained under the enhanced fountain regime, with gas production reaching a value of 1.3 m3 kg−1 and that of H2 production 5.0 wt%.

The hydrogen production by steam reforming (SR) of raw bio-oil (obtained by fast pyrolysis of pine sawdust) has been studied in a continuous two-step process, which consists of a thermal treatment at 500 °C, followed by SR in a fluidized bed reactor with Ni/La2O3-αAl2O3 catalyst. The effect of SR temperature on bio-oil conversion, product yields and catalyst deactivation was evaluated in the 550–700 °C range. The bio-oil conversion and H2 yield were significantly enhanced by increasing temperature. A H2 yield of around 88% and low catalyst deactivation were achieved at temperatures above 650 °C, for a S/C (steam/carbon) ratio of 6 and space-time of 0.10 gcatalysth/gbio-oil. The influence temperature has on product yields and catalyst deactivation was explained by the different nature of the coke deposited. The temperature-programmed oxidation (TPO) curves of coke combustion allow identifying two fractions: i) Coke I, which is the main responsible for deactivation (by encapsulating the Ni sites), whose formation depends on the concentration of bio-oil oxygenates; ii) Coke II, which has filamentous nature and CO and CH4 as main precursors. The effect of temperature on the formation of both types of coke depends on the space–time. Thus, for low values (0.04 gcatalysth/gbio-oil) there is significant formation of both types of coke, with their content increasing with temperature. For higher values (0.38 gcatalysth/gbio-oil), the increase in reaction temperature promotes the removal of coke I, and therefore this is the prevailing fraction at 550 °C and is negligible at 700 °C. This fact is of special relevance for attenuating the Ni/La2O3-αAl2O3 catalyst deactivation.

Pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor (500 °C) and the volatiles have been reformed in-line over a Ni commercial catalyst in a fluidized bed reactor. The evolution of reaction indices (conversion, H 2 yield and other gaseous product yields) with time on stream has been studied under the following operating conditions: temperature, 600–700 °C; space-time, 8.3–20.8 g cat min g HDPE − 1 , and steam/plastic ratio, 3–5. High initial conversion (> 94.5%) and H 2 yields (> 76.7%) are attained under all the operating conditions studied, with HDPE conversion and H 2 yield increasing when the three variables are increased, which is explained by the enhancement of the reforming reaction. However, a significant effect of operating conditions on catalyst stability has been observed. Thus, an increase in temperature, space-time and steam/plastic ratio decreases catalyst deactivation as a consequence of a lower rate of coke deposition on the catalyst due to both a lower C 5 + coke precursor amount in the reaction medium and a higher gasification rate of the coke deposited.