Pyrolysis of Polyolefins in a Conical Spouted Bed Reactor: A Way to Obtain Valuable Products

The amount of waste plastic increases every single year, which causes a critical environmental issue. Polyolefins (mainly high‐ and low‐density polyethylene and polypropylene) are the most common types of plastics, accounting for 60 wt% of the plastic waste. Pyrolysis, the thermal degradation in an inert atmosphere, is considered to be one of the most appealing technologies for the recycling of plastic materials. The conical spouted bed reactor is suitable for the pyrolysis of plastic waste due to its ability to avoid agglomeration problems that may be caused by the melted plastic. The pyrolysis process may be carried out at different temperatures and with or without the presence of catalysts in the reaction environment in order to streamline product distribution. The resulting products are hydrocarbons: non‐condensable gases (C1–C4), gasoline fraction, diesel fraction, and waxes. These fractions might be used directly as feed streams for refinery units or as pools to be mixed with other streams from refineries

Novel method to meassure fine particle circulation rates in draft tube conical spouted beds

The spouted bed regime is an alternative contact method to fixed and fluidized beds. The ratio between the inlet diameter and particle diameter limits the scaling-up of spouted beds (the inlet diameter should be smaller than 20-30 times the particle diameter). The insertion of a draft tube is the way of overcoming this limitation. Particle cycle time is defined as the time the particle takes to travel from the top of the annulus downwards and back again to its starting point. Since the proportion of time spent by a particle in the spout is insignificant compared with that spent in the annulus, particle cycle times can be deduced from solid flow patterns in the annulus (1). Knowledge of particle cycle time is very useful to ascertain the bases of the spouted bed technique. Furthermore, information on this parameter and particle trajectories is essential for spouted bed applications, given that the average cycle time regulates energy and mass transfer, and influences chemical reactions (2). The most used technique to measure the solid cycle times is particle tracking, but monitoring of fine particles requires very sofisticated techniques, whose reliability is open to debate. Accordingly, the main aim of this work is to setup a device and develop a methodology for measuring the circulation rate of fine particles in conical spouted beds. The device is a sector located on the upper surface of the annulus, which collects the particles raining down in the fountain. Based on the information gathered, the factors of major influence on the solid circulation rate are determined and their effect is quantified. The material used for operation is building sand of0.6 mmparticle diameter, but glass beads (coarse particles) of4 mmdiameter have also been used so as to verify the methodology proposed by comparing the results with those obtained by monitoring a marked (painted) particle. REFERENCES 1. N. Epstein, J.R. Grace. Eds. Cambridge University Press: New York, 2011. 2. J. Makibar, A.R. Fernandez-Akarregi, I. Alava, F. Cueva, G. Lopez and M. Olazar. Investigations on heat transfer and hydrodinamics under pirolisis conditions of a pilot-plant draft tube conical spouted bed reactor. Chem. Eng. Process., 50: 790-798, 2011

Development of the Conical Spouted Bed Technology for Biomass and Waste Plastic Gasification

Gasification is one of the most effective methods for upgrading different wastes, such as plastics and biomass, because the gas produced can be used directly as a fuel or as a renewable raw material for the production of chemicals and fuels. The conical spouted bed reactor (CSBR) has demonstrated to perform well in gasification process due to its specific features, such as (i) the cyclic and vigorous particle movement that avoids bed defluidization (a limitation in fluidized beds), (ii) capability for handling irregular or sticky solids, (iii) high heat transfer rates between phases, and (iv) bed stability in a wide range of gas flow rates. However, the conventional CSBR is characterized by its short residence time, which involves serious problems for minimizing tar formation. The incorporation of a fountain confiner in the CSBR is key to increasing the gas residence time and improving the contact between the gas and heat carrier particles, thereby promoting tar cracking reactions and so enhancing carbon conversion efficiency from 81.5% (without confiner) to 86.1% under fountain enhanced regime. The quality of the syngas is clearly improved as the H2 concentration increases from 36 to 42% with and without the fountain confiner, whereas that of CO decreases from 34 to 29%, respectively

A CONICAL SPOUTED BED REACTOR FOR THE VALORISATION OF WASTE TIRES

A pilot plant provided with a conical spouted bed reactor has been used for the valorisation of waste tires by thermal pyrolysis in continuous mode. The effect of pyrolysis temperature on product distribution and properties has been studied in the temperature range from 425 to 600 ºC. This variable has proven to have an important effect on product distribution. Thus, pyrolysis oil yield was reduced from 64.3 wt% at 425 ºC to 55.9 wt% at 600 ºC. However, the quality of carbon black was improved operating at high temperatures (increasing BET surface area values). High yields of certain interesting chemicals have been obtained in the liquid fraction, such as limonene (19.3 wt%), isoprene (5.7 wt%) and styrene (6.1 wt%)

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

Hydrodynamic Aspects and Correlations for the Design of Draft-Tube Conical Spouted Beds

A study has been carried out on the hydrodynamics of conical spouted beds with draft tube. Correlations have been proposed for calculating minimum spouting velocity, operating pressure drop and peak pressure drop as functions of dimensionless module that take into account geometric factors, particle characteristics and operating conditions

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)

Catalytic pyrolysis of date palm seeds on HZSM-5 and dolomite in a pyroprobe reactor in line with GC/MS

Catalytic pyrolysis of date palm seeds (DPS) has been carried out in a pyroprobe connected online with a GC/MS. The effect of a HZSM-5 zeolite on the product distribution has been studied at 450 and 500 °C by using different catalyst/biomass mass ratios (1, 2, 5) and that of a dolomite catalyst at 450 °C using a catalyst/biomass mass ratio of one. Product distributions have been monitored and their trends explained based on the properties of the catalysts used. The HZSM-5 promotes the formation of incondensable gases and aromatic hydrocarbons due to its high acidity and shape selectivity. The concentrations of incondensable gases and hydrocarbons increase markedly with the catalyst/biomass mass ratio, with their peak area percentages ranging from 23.6 to 54.1% and from 7.1 to 24.5%, respectively. At the same time, a significative reduction in the amount of acids, ketones, phenols, furans, and anhydrosugars has been determined. The dolomite catalyst enhances ketonization reactions, which leads to a significant increase in the content of ketones, accounting for a value of around 27%.The authors gratefully acknowledge the Tunisian Ministry of Higher Education and Scientific Research (MESRST), the Spanish Ministry of Science and Innovation (PID2019-107357RB-I00) (AEI/FEDER, UE), and the Basque Government (KK-2020/00107) for their financial support.Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. 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

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