In depth characterisation of hydrocyclones: Ascertaining the effect of geometry and operating conditions on their performance

Hydrocyclones are used for densification of waste streams prior to drying or for classification of solid and liquids in two-phase streams. They are becoming popular in industrial units due to their simplicity, low energy consumption and high versatility. However, the effect of geometry and operating conditions on the cut diameter and solid recovery efficiency have been independently studied, and therefore there are no studies approaching the influence of all the parameters simultaneously. Thus, a detailed experimental study was conducted to ascertain the effect of the hydrocyclone body (diameter and angle) and the vortex finder and spigot size and shape, as well as operating conditions (inlet pressure and solid concentration) on the separation efficiency curve, cut diameter, solid and volume recovery and the main features of the outlet streams. It has been proven that separation efficiency and outlet stream composition are sensitive to both the geometry of the hydrocyclone and the operating parameters. Therefore, knowledge of their influence is essential for the design of industrial units where liquid reutilisation is a major concernThis work has been carried out with the financial support from the University of the Basque Country UPV/EHU (Projects US12=11 and US16=26) and the collaboration of Novattia Desarrollos Ltd. Javier Izquierdo thanks the University of the Basque Country UPV/EHU for his Ph.D. grant. Xabier Sukunza thanks the Ministry of Economy and Competitiveness for his Ph.D. grant (FPU18=04935)

Activity and stability of different Fe loaded primary catalysts for tar elimination

[EN] The performance of olivine, dolomite and gamma-alumina primary catalysts was evaluated in the continuous tar elimination process in which toluene was selected as the biomass gasification tar model compound. Iron was incorporated into these catalysts in order to improve their catalytic activity. All the experiments were performed in a continuous flow fluidized bed micro-reactor, with a steam/toluene ratio of 4 and a space velocity (GHSV) of 820 h(-1), which corresponds to a catalyst amount of 3.8 cm(3). The effect of temperature was studied using olivine in the 800-900 degrees C range, which allowed concluding that 850 degrees C was the best temperature for tar removal. The fresh and deactivated catalysts were characterized by N-2 adsorption-desorption, X-ray fluorescence (XRF), X-ray diffraction (XRD) and temperature-programmed oxidation (TPO). Tar conversion efficiency was assessed by means of carbon conversion, H-2 yield (based on the maximum allowed by stoichiometry), gas composition and product yields, with Fe/Al2O3 leading to the highest conversion (87.6 %) and H-2 yield (38 %). Likewise, Fe/Al2O3 also provided the highest stability, as it allowed operating for long periods with high conversion values (85.9 % after 35 min on stream), although it underwent severe deactivation. The analysis of the spent catalysts revealed that deactivation occurred mainly by coke deposition on the catalyst surface and iron phase oxidation, with Fe/olivine and Fe/dolomite leading to the faster deactivation due to their poorer metal dispersion related to their reduced surface area. The TPO profiles showed that the coke deposited on the three catalysts was amorphous with a very small contribution of highly structured carbon.This work was carried out with the financial support of the grants RTI2018-098283-J-I00 and PID2019−107357RB-I00 funded by MCIN/AEI/ 10.13039/501100011033 and by “ERDF A way of making Europe” and the grants IT1218−19 and KK-2020/00107 funded by the Basque Government. 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

Biomasa hondakinak balioztatzeko prozesu motak

Lan honetan biomasa hondakinak balioztatzeko prozesu nagusiak aztertu dira. Alderaketaren ardatzak honelakoak izan dira: lehengaiaren hezetasuna, erreakzioa burutzeko baldintzak (batik bat, konbertsio-denbora eta tenperatura), lortutako produktuak eta teknologiaren heldutasuna. Biomasa balioztatzeko erabiltzen diren teknologiak bi talde nagusitan banatu daitezke: Termokimikoak eta biokimikoak. Konbertsio termokimikoan oinarritzen diren prozesu nagusiak errekuntza, gasifikazioa, torrefakzioa eta pirolisia dira. Erreakzioak tenperatura altuan egiten direnez, konbertsio-denbora baxua izan ohi da. Komenigarria da prozesu hauetan lehengai lehorrak (basogintza, nekazaritza eta abeltzaintza ustiaketetako hondakinak eta papergintza industriako hondakinak) erabiltzea. Bestalde, prozesu biokimiko edo biologikoetan, mikroorganismoek erreakzioan parte hartzen dute eta lehengai hezeak erabiltzen dira: mindak, gorotzak, araztegietako hondakin uren lohiak eta elikadura-industriako hondakin organikoak. Prozesu nagusiak konpostatzea, digestio anaerobikoa eta hartzidura alkoholikoa dira. Tenperatura baxua izaten da (70ºC baino baxuagoa) eta ondorioz, erreakzio-denbora luzea eta bolumen handiko erreaktorea behar da. Erreakzioak burutzeko, egunak (hartzidura alkoholikoan), asteak (digestio anaerobikoan) edo hilabeteak (konpostatzearen kasuan) behar dira

Application of Green Polymeric Nanocomposites for Enhanced Oil Recovery by Spontaneous Imbibition from Carbonate Reservoirs

This study experimentally investigates the effect of green polymeric nanoparticles on the interfacial tension (IFT) and wettability of carbonate reservoirs to effectively change the enhanced oil recovery (EOR) parameters. This experimental study compares the performance of xanthan/magnetite/SiO2 nanocomposites (NC) and several green materials, i.e., eucalyptus plant nanocomposites (ENC) and walnut shell ones (WNC) on the oil recovery with performing series of spontaneous imbibition tests. Scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDAX), and BET (Brunauer, Emmett, and Teller) surface analysis tests are also applied to monitor the morphology and crystalline structure of NC, ENC, and WNC. Then, the IFT and contact angle (CA) were measured in the presence of these materials under various reservoir conditions and solvent salinities. It was found that both ENC and WNC nanocomposites decreased CA and IFT, but ENC performed better than WNC under different salinities, namely, seawater (SW), double diluted salted (2 SW), ten times diluted seawater (10 SW), formation water (FW), and distilled water (DIW), which were applied at 70 °C, 2000 psi, and 0.05 wt.% nanocomposites concentration. Based on better results, ENC nanofluid at salinity concentrations of 10 SW and 2 SW ENC were selected for the EOR of carbonate rocks under reservoir conditions. The contact angles of ENC nanocomposites at the salinities of 2 SW and 10 SW were 49 and 43.4°, respectively. Zeta potential values were −44.39 and −46.58 for 2 SW and 10 SW ENC nanofluids, which is evidence of the high stability of ENC nanocomposites. The imbibition results at 70 °C and 2000 psi with 0.05 wt.% ENC at 10 SW and 2 SW led to incremental oil recoveries of 64.13% and 60.12%, respectively, compared to NC, which was 46.16%.The publication of this article was funded by the Qatar National Library

A novel alternative method for pistachio nuts splitting using conical spouted beds

Closed shell pistachio nuts must be split for their commercialisation, which is conducted in processing plants designed on purpose. Given that current industrial processes have limitations, and pistachio is a booming product, new opening mechanisms alternative to the traditional ones are being developed. Thus, thermal processing has recently gained attention, but the high energy consumption required in these processes has boosted the search of new alternatives. To our knowledge, there is no information about the treatment of pistachio nuts in conical spouted beds. Accordingly, we propose a novel alternative method for pistachio nuts splitting by involving the mentioned technology. Hydrodynamic runs have been conducted to ascertain the configurations that lead to stable operation, and therefore are suitable for low temperature batch drying and splitting of pistachio nuts. The results show that a single cycle of wetting, drying and cooling of pistachio nuts allows attaining splitting percentages of up to 35%.This work has received funding from Spain's Ministry of Science and Innovation (PID2019-107357RB-I00 (AEI/FEDER, UE) and PLE2021-008062 (European Union NextGenerationEU/PRTR)), the European Commission (HORIZON H2020-MSCA RISE-2018, Contract No.: 823745), the Basque Government (IT) and the University of the Basque Country, UPV/EHU (US18/18). Xabier Sukunza thanks the Ministry of Economy and Competitiveness for his Ph.D. grant (FPU18/04935). Maider Bolaños is grateful for her Ph.D. grant (PIF21/69) from the University of the Basque Country UPV/EHU

Bed symmetry in the fountain confined conical spouted beds with open-sided draft tubes

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)

Conversion of HDPE into Value Products by Fast Pyrolysis Using FCC Spent Catalysts in a Fountain Confined Conical Spouted Bed Reactor

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 degrees C) and space-time (7-45 g(cat) min g(HDPE)(-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 degrees C. The main product fraction obtained in the catalytic cracking was made up of C-5-C-11 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).This work was carried out with the financial support from Spain's ministries of Science, Innovation and Universities RTI2018-101678-BI00(MCIU/AEI/FEDER, UE) and 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 Skodowska-Curie grant agreement No. 823745, and the Basque Government (IT1218-19 and KK-2020/00107)

Solid-fluid mixing behavior of conical spouted beds with internal devices

The effect of draft tubes and fountain confiner on the gas and solids mixing behavior is studied in conical spouted beds. Accordingly, the bed porosity has been determined in different hydrodynamic regimes of 1:1; 1:25 and 1:5 u=ums , with beds equipped with draft tubes of 0%; 56% and 100% opening ratio. These devices significantly affect the gas residence time and particle cycle time distributions, which are further improved by using a fountain confiner, specially when high inlet gas flow rates are desired. The addition of this device was found to remove stagnant gas pockets over the annular zone, while reducing the par- ticle cycle time by 15% with the OSDT configuration at 1:5 u=u ms . This reduction heavily depends on the distance between the bed surface and the fountain confiner. By including draft tubes, the expected par- ticle cycle time can be more than doubled due to the reduced annular-spot solids circulation. Therefore, it was found that a combination of internal devices and operating flow rate present a promising strategy to control the gas flow pattern, while keeping the distribution of particles cycle times required for each application.This work has been carried out with the financial support from the Spain’s Ministries of Economy and Competitiveness (CTQ2016- 75535-RðAEI=FEDER; UEÞ) and Science and Innovation (PDI2019-107357RB-I00ðAEI=FEDER; UEÞ), the Basque Government (IT218-19) and the University of the Basque Country UPV/EHU (US16/21). Aitor Atxutegi is grateful for his Ph.D. grant from the University of the Basque Country UPV/EHU(PFI15-2017)