Spouted Bed Reactor Research Articles

Carbon Capture Using Sodium Carbonate Solution in a Spouted Bed Reactor along with Absorbent Regeneration

Carbon Capture Using Sodium Carbonate Solution in a Spouted Bed Reactor along with Absorbent Regeneration

From circular to square‐based section spouted beds: Scale‐up and design overview of a multistage thermal unit

AbstractThis work summarizes the results of several research projects to demonstrate the possibility of scaling‐up spouted beds by assembling a number of square‐based jet units. Cylindrical vessels with a bottom cone and parallelepiped ones with a frustum base do not differ to a large extent in terms of hydrodynamic features. The existing correlations can be used to predict these square‐based spouted beds. Spouted beds can be very reasonably described as well‐mixed reactors. By assembling several units, it is possible to approach a plug flow state for solids residence time distribution (RTD) in continuous processes. Spouting stability is fully reached when the modules do not interfere each other: this goal is obtained by positioning the downstream units at a certain lower level and having the solids move by overflow; placing internal vertical baffles between contiguous units is the solution. Two hydrodynamical models are proposed to describe single and multiple spouted beds; their predictions help in choosing the best geometrical configuration for the assemblage. A possible application of a multiple spouted bed reactor was envisaged for gasifying pelletized textile residues to generate syngas which can be directly used in situ as a co‐fuel. Two units were built: a single 0.2 m side square‐based spouted bed furnace and the consequent dual stage scale‐up apparatus suitable for an auto thermal process. In the bottom stage, four units work independently to run combustion/gasification of low‐quality solid residues, while the upper stage had a cascade of four modules to run pyrolysis/gasification of selected biomass and obtain valuable secondary products.

Biomass source influence on hydrogen production through pyrolysis and in line oxidative steam reforming.

This study evaluates the potential of several biomasses differing in nature and composition for their valorization by pyrolysis and in-line oxidative steam reforming. The first task involved the fast pyrolysis of the biomasses in a conical spouted bed reactor at 500ºC, in which product yields were analyzed in detail. Then, the oxidative steam reforming of pyrolysis volatiles (gases and bio-oil) was approached in a fluidized bed reactor. The reforming experiments were performed at 600 ºC, with an steam/biomass (S/B) ratio of 3 and catalyst (Ni/Al2O3) space times of 7.5 and 20 gcat min gvol-1. Concerning equivalence ratio (ER), a value of 0.12 was selected to ensure autothermal operation. Remarkable differences were observed in H2 production depending on the type of biomass. Thus, pine wood led to a H2 production of 9.3 wt%. The lower productions obtained with rice husk (7.7 wt%) and orange peel (5.5 wt%) are associated with their higher ash and fixed carbon content, respectively, which limit the efficiency of biomass conversion to bio-oil. However, in the case of the microalga, the poor performance observed is due to the lower conversion in the reforming step toward gases due to the composition of its pyrolysis volatile stream.

Turning Waste into Wealth: A Conceptual Design of Limonene Production Plant from Waste Rubber Tyre

Limonene production represents a compelling opportunity in the global market, given its competitive landscape dominated by a few key players who control nearly half of the industrial-grade limonene market. Due to the high polyisoprene content in vehicle tyres, along with the rising number of waste rubber tyres, the production of limonene by pyrolysis of tyres may represent a future trend to turn waste into wealth. Hence, a conceptual plant design was carried out to determine the feasibility of limonene production from waste rubber tyres in Malaysia. This feasibility study involved Aspen Plus simulation and illustrated the main processes using Process Flow Diagram (PFD), Piping and Instrumentation Diagram (P&ID), and comprehensive stream table integrating material and energy balances. The desired product, which is limonene, was produced by the gas-solid pyrolysis within a conical spouted bed reactor (CSBR) in an inert atmosphere of non-oxidizing, achieving limonene of 98% purity. Besides, process optimization via pinch analysis has been performed to recover 223.84 kWh of energy using heat integration, resulting in 62.06% of energy saving. From the economic analysis conducted, the total capital investment is RM12.9 million and the annual revenue is RM124.7 million with an annual limonene production of 543.1 tons. The financial analysis demonstrated a robust return on investment (ROI) of 303%, a simple payback period of 0.33 years and ta Net Present Value (NPV) of RM 432.2 million.

Selective H2 production from plastic waste through pyrolysis and in-line oxidative steam reforming

This study deals with the proposal of pyrolysis and in-line oxidative steam reforming (P-OSR) for plastic waste valorization and assesses the potential of this strategy for the selective production of H2. Overall, the study aims at progressing towards the fine-tuning of the pyrolysis-reforming technology by co-feeding O2. Thus, a multi-point O2 injection system has been developed to ensure a suitable O2 distribution in the reforming reactor and avoid the formation of hot spots, as they may cause catalyst deactivation by metal sintering. Moreover, as O2 is directly supplied into the catalytic bed, pre-combustion of the volatile stream before contacting the catalyst is avoided and in-situ coke combustion is promoted. The P-OSR of HDPE was carried out in a two-step reaction system, which combines CSBR (conical spouted bed reactor) and FBR (fluidized bed reactor) technologies. The experiments were conducted in continuous mode and the influence of the main process conditions at zero time on stream was analyzed. Thus, the effect of reforming temperature was studied in the 550–750 °C range, that of the space time from 3.12 to 15.62 gcat min gHDPE−1, steam to plastic (S/P) ratio between 2 and 5 and equivalence ratio (ER) from 0 to 0.3. Under the optimum conditions (700 °C, S/P of 3, 12.5 gcat min gHDPE−1 and ER of 0.2), a H2 production of 25.0 wt% was obtained, which is only 28.6 % lower than that obtained in the conventional pyrolysis-steam reforming (P-SR) process. The results obtained confirm the potential of continuous P-OSR process for the selective production of H2.

Oxide Reduction Treatment with a Thermal Plasma Torch: A Case Study

This article presents the findings of a study on oxide reduction utilizing a novel reducing plasma torch, employing greenhouse gases such as CO2 and CH4 as plasma gases. The primary aim of this investigation is to establish the viability of this approach. The innovative plasma torch was employed to reduce various oxides, including aluminum oxide, iron oxide, and titanium oxide, as well as a mixed oxide composition, employing a CO2/CH4 molar ratio of 1:1 within a spouted bed reactor. Following plasma treatment, X-ray diffraction (XRD) analysis was conducted to examine the metallic phases, notably titanium, iron, and aluminum. SEM–EDS observations were carried out to assess microstructural changes and identify elemental compositions pre- and post-plasma treatment. The results demonstrate that within the conical section of the reactor, titanium oxide experiences partial reduction, resulting in limited titanium production, while aluminum oxide and iron oxides (magnetite and hematite) undergo reduction to yield aluminum and iron, respectively. Thermodynamic calculations, performed using Factsage software version 8.3, were utilized to predict stable-phase formations following plasma treatment for each material.

Catalytic pyrolysis of brewer's spent grain in spouted bed reactor using calcium oxide for upgrading oil

This study investigates the potential of brewer's spent grain as a fuel source through fast pyrolysis in a spouted bed reactor, aiming to contribute to sustainable fuel alternatives and the mitigation of the environmental consequences of fossil fuel consumption. Both non-catalytic and catalytic tests evaluated the effects of temperature, biomass feed rate, and catalyst concentration on yields and hydrocarbon composition. The intermediate temperature (550 °C) and biomass feed rate (960 g/h) were optimal for non-catalytic tests, favoring oil production. Additionally, the oil yield was enhanced with the use of CaO as a catalyst during the pyrolysis process. An optimization study identified conditions maximizing both liquid yield and hydrocarbon content. While catalytic tests showed a modest increase in oil yield compared to non-catalytic tests, the addition of CaO significantly improved oil quality by increasing hydrocarbon concentration and facilitating deoxygenation. Under optimal conditions, non-catalytic pyrolysis achieved a 41% liquid yield with 15% hydrocarbon content. For catalytic pyrolysis, optimal conditions yielded 43% oil with a hydrocarbon content of 33% and low water content. Moreover, the resulting oil exhibited a higher heating value (HHV) of 25.7 MJ/kg compared to the spent grain's 19.8 MJ/kg. Utilizing the CaO catalyst further increased the HHV value to 28.2 MJ/kg, highlighting its efficiency in enhancing liquid product quality. The solid products resembled mineral coals with higher energy density compared to the feedstock. This study highlights the potential of brewer's spent grain for fuel production in a spouted bed reactor and the CaO catalyst's effectiveness in improving liquid product quality.

Review of Experimental Activities and Recent Developments of Spouted Bed Reactors at Different Operational Scales

Recent research advances and technological developments of spouted bed reactors (SBRs) have been discussed in this work. SBR has aroused increasing interest since their invention in 1955 due to its flexibility in processing different feedstocks and the high process yields that can be achieved due to its characteristic fluid dynamics. However, even though highly satisfactory results have been obtained at the laboratory scale for different applications (i.e., drying or thermochemical reactions, among others), their full implementation at an industrial level is still scarce, mainly due to the challenges encountered for their scale-up. In this work, an initial short description of SBR and configurations is followed by a review of the main experimental activities that have been conducted at different scales in the period 2013–2023. Advanced solutions such as multi-unit reactors and the use of rectangular geometries instead of the classical cylindrical ones have arisen as potential areas for further study and development to achieve a reliable implementation of the spouted bed technology at an industrial scale.

Numerical simulation study of impact of polydispersity on biomass pyrolysis in draft-tube spouted reactor with fountain confiner

During biomass pyrolysis within spouted reactor, particles exhibit behavior characterized by polydispersity. To explore the impact of polydispersity of bed materials on the biomass pyrolysis, the multiphase particle-in-cell model is constructed to simulate such process. The focus of the study is examining the impact of size distribution of solid materials and the presence of a draft tube on the particle-level properties. The results show that the yields of Gas1 and tar during the first pyrolysis increase about 13.1 % and 14.8 %, respectively, as the PSD width of sand increase from 0.1 to 0.7. In addition, the influence of the draft tube is primarily centered on enhancing interphase interactions rather than pyrolysis yields when a fountain confiner is applied. Fine particles mainly distribute along the interphase of annulus and its vicinity while coarse particles mainly accumulate along the interphase of annulus and spout. Expanding the PSD widths of bed materials from 0.1 to 0.7 results in an approximate temperature increase of 10 K in the floating biomass. The variation of particle slip velocity and heat transfer coefficient exhibits similar trend, mainly due to their interrelation in convective heat transfer. These findings hold valuable insights that can guide optimization design and parameter selection in the conical fountain confined spouted bed reactors.

Insight into the joint valorization of CO2 and waste plastics by pyrolysis and in line dry reforming for syngas production

This paper assesses the potential of plastics valorization by pyrolysis and in line catalytic dry reforming for syngas production. Previous studies showed the suitability of a continuous process made up of a conical spouted bed reactor for fast pyrolysis and a fluidized bed reactor for catalytic steam reforming. In order to step further in the application of this technology under dry reforming conditions, equilibrium simulation was approached to analyze process performance, as the development and optimization of this technology for the production of high-quality syngas requires understanding in detail the complex influence of process parameters. Thus, this study deals with the influence of main process parameters, namely, temperature, CO2/C ratio and the type of plastic, on the process performance. Furthermore, the role played by steam co-feeding in the dry reforming in order to adjust syngas H2/CO ratio was evaluated by varying the steam/carbon ratio. The obtained results clearly show that a strict control of process conditions is required to ensure high conversion to syngas and avoid undesired reactions, such as reverse WGS. Among the plastics studied, polyolefins are those of highest potential for syngas production, but polystyrene allows producing a high quality syngas through a combined reforming strategy.

Steps to understand the role played by the main operating conditions in the oxidative steam reforming of biomass fast pyrolysis volatiles

Biomass pyrolysis and in-line catalytic oxidative steam reforming of the volatiles (P-OSR) has been analyzed in a two-step reaction system made up of a conical spouted bed reactor (CSBR) and a fluidized bed reactor (FBR). A novel O2 multi-point injection system has been designed in order to ensure suitable O2 distribution in the FBR, and hence avoid the formation of hot spots that may lead to irreversible catalyst deactivation by metal sintering. Optimization of the main process parameters has been approached in order to maximize H2 production and overcome the high energy requirements of the endothermic reforming reaction. The study has been conducted in the following ranges of the operating conditions: Reforming temperature, 550–700 °C; space time, 5–20 gcat min gvolatiles−1; steam/biomass (S/B) ratio, 2.5–5; and equivalence ratio (ER) from 0 to 0.19. Moderate reforming temperatures (600–650 °C), a S/B value of 3 and a space time of 15 gcat min gvolatiles−1 are the optimum conditions for the process. Furthermore, when low space time values are used, O2 feeding rates into the reforming step of up to an ER value of 0.12 (corresponding to autothermal operation (ATR)) revealed a synergistic effect promoting reforming reactions. Thus, an improvement in H2 production from 6.81 wt% to 8.26 wt% was observed by changing ER from 0 to 0.12, which means H2 production increases by 21.4% compared to the conventional pyrolysis-reforming (P-SR) process. Therefore, the promising results obtained in this study prove the suitability of the continuous P-OSR strategy for H2 production from biomass and involve a step forward towards the scaling up of the process.

Pyrolysis as a value added method for plastic waste management: A review on converting LDPE and HDPE waste into fuel

The global demand for plastic is increasing year by year due to its indispensable uses and excellent properties. Plastic wastes persist for many years due to their slow deterioration and cause severe environmental problems. Therefore, there is a growing focus worldwide on plastic waste disposal methods to overcome adverse environmental impacts. As plastics are petroleum-based materials, the pyrolysis of plastics to fuel oil, gases, and char, has more concern than the other plastic waste management methods of recycling and landfilling. A yield of 70-80 wt.% of liquid fuel from pyrolysis waste has been reported elsewhere, emerging the importance and aptness of this method in plastic waste management. The common reactor types for the pyrolysis process are batch reactor, semi-batch reactor, spouted bed reactor, and fluidized bed reactor. The common catalysts employed in plastic pyrolysis were zeolites, including ZSM-5, HUSY, Zeolite X, and Y. The pore structure and the catalyst’s acidity are the most influencing parameters in increasing the liquid yield and the quality of the oil produced in the pyrolysis process. This paper reviews the existing literature on pyrolysis processes developed for HDPE and LDPE wastes globally and their governing factors. Furthermore, emissions in the pyrolysis process and engine combustion of the fuel oil, performance, and emission characteristics were discussed. Although plastic waste separation prior to its management is a challenging process, this review highlights the conversion of waste plastic into energy as a smart way to meet the rising demands.

Influence of oxidative conditions on the deactivation of an equilibrium FCC catalyst in the fast pyrolysis of HDPE in a conical spouted bed reactor

This study approaches the continuous catalytic fast pyrolysis of plastics in a flexible and original technology, i.e., a conical spouted bed reactor equipped with fountain confiner and draft tube. The catalyst is an inexpensive equilibrium fluid catalytic cracking (FCC) one. Moreover, operation under oxidative conditions is proposed to solve heat supply to the pyrolysis reactor, as a previous study revealed a remarkable difference in the performance of the cracking catalyst when pyrolysis was carried out under inert (conventional) and oxidative conditions. Therefore, the aim of this paper is to assess the role played in the catalyst stability and deactivation mechanism by the presence of air in the reaction environment. A comparative study has been conducted by operating in long continuous runs under the same conditions (550 °C and a space time of 15 gcatalyst min gHDPE−1) in inert and oxidative atmospheres, i.e., equivalence ratios (ER) of 0 and 0.2, respectively. The evolution of product distribution with time on stream was evaluated. Moreover, samples of catalysts were taken from the reactor at different reaction times to correlate catalyst performance with the deactivated catalyst properties, and therefore progress in the understanding of the deactivation mechanism. The amount and nature of the coke deposited on the catalyst and its influence on catalyst properties was ascertained using thermogravimetry (TG-TPO), Raman spectroscopy, and NH3 and N2 adsorption–desorption techniques. The operation under oxidative conditions improved product distribution, with higher yields of light olefins. Moreover, catalysts activity and stability were also enhanced under oxidative conditions. Therefore, the results obtained involve a step forward towards the scaling up of plastics continuous catalytic pyrolysis.

Numerical evaluation of multi-scale properties in biomass fast pyrolysis in fountain confined conical spouted bed

Biomass fast pyrolysis is one of the promising ways to convert cellulose and lignin into available biochar, bio-oil and product gases. In the current work, the process of biomass fast pyrolysis is numerically studied via the reactive multiphase particle-in-cell (MP-PIC) model in a conical fountain confined spouted fluidized bed to investigate gas-solid motion (e.g., gas and solid fluxes) and particle-scale characteristics (e.g., particle velocity, residence time, temperature, heat transfer coefficient and dispersity). Simulation results have been well validated with experimental data. Biomass and sand behaviors in scenarios with and without fountain confiners have been comprehensively compared. It is recommended to insert a fountain confiner in spouted bed reactor because it can significantly increase the yields of Gas1 and tar of about 115.1% and 118.8%, respectively. The presence of the fountain confiner has resulted in an upward shift of the maximum temperature and HTC for biomass and sand particles, resulting from the enlarged amount of particle accumulation. Due to large temperature difference, biomass and sand particles have highest HTCs at inlet of about 200 W/m2·K and 120 W/m2·K, respectively. The axial dispersion coefficients of biomass and sand particles are two orders larger than the radial one, resulting from distinctive flow pattern in the spouted bed. The axial dispersion coefficients of biomass and sand particles in the fountain confined spouted bed are 1.93 × 10−3 m2/s and 2.40 × 10−4 m2/s, respectively. The relationships between particle parameters in conventional and fountain confined spouted beds are compared. The findings of this study can provide valuable insights into assisting designers in optimizing the design of such reactors.

Health and Carcinogenic Risk Assessment of Exposure to by-Products of Photocatalytic Degradation of Toluene in a Spouted Bed Reactor with Porous and Non-Porous Draft Tube.

This study was performed to assessment the health and carcinogenic risk of exposure to by-products of photocatalytic degradation of toluene in a spouted bed reactor Equipped with porous and non-porous draft tube. For this purpose, titanium dioxide nanoparticles were used as photocatalysts and UV lamps as radiation sources. Degradation efficiency and CO2 selectivity were compared. By-products were also detected in three spouted bed reactors with and without a porous and non-porous draft tube. The results revealed that the degradation efficiency of toluene in the spouted bed reactor without a draft tube was 30.75%. The insertion of porous and non-porous draft tubes in the spouted bed reactor increased the degradation efficiency up to 54.88% and 47.63%, respectively. Meantime, CO2 selectivity decreased from 100% to 50.8% within 180 min irradiation time in the spouted bed reactor without draft tube, while in the spouted bed reactors with porous and non-porous draft tube maintained at 89.85% and 84.35%, respectively. Toluene and four by-products with carcinogenic and non-carcinogenic risk of 0.002176 and 182.2, respectively, were detected in the spouted bed reactors without draft tube. However, no by-products with carcinogenic risk were found in the spouted bed reactor with porous and non-porous draft tube. photocatalytic degradation of toluene in a spouted bed reactor without a draft tube produces by-products with health and carcinogenic risks. The insertion of a porous and non-porous draft tube in spouted bed reactors provided mineralization more complete than spouted bed reactor without a draft tube by reducing the dead zone and providing appropriate contact between the toluene, photocatalyst, and UV. Therefore, prevent the formation of dangerous and carcinogenic by-products.

Syngas production by bio-oil steam gasification in a fountain confined conical spouted bed reactor

The combination of delocalized units for the fast pyrolysis of biomass to produce bio-oil followed by centralized units for the gasification of bio-oil appears as an economically attractive option for the full-scale production of syngas because transportation of bio-oil is less costly than that of biomass. First goal of this study lies in the validation of a bio-oil feeding device made up of a line-thermostated at 60–80 °C and a non-atomizing injector cooled by water. This injector allows feeding the crude bio-oil in continuous mode into the conical spouted bed reactor without being clogged by the pyrolytic lignin in the bio-oil. The effect of gasification temperature on gas properties, tar composition, and carbon conversion efficiency were assessed in the 800–900 °C range. The results show that temperature promotes tar reduction (from 40.7 to 12.5 g/Nm3), carbon conversion efficiency (from 91.2 to 96.3 %) and gas yield (from 1.37 to 1.85 Nm3/kg on a dry basis) as temperature is increased from 800 to 900 °C. A novel aspect of this study is the detailed characterization of the tar evolution with temperature, which, to our knowledge, is an aspect that has not been approached in the literature related to raw bio-oil gasification.

OPTIMIZING THE STRUCTURAL CHARACTERISTICS OF DRAFT TUBE IN A SPOUTED BED REACTOR FOR BEST PHOTOCATALYTIC DEGRADATION OF TOLUENE AND CO2 SELECTIVITY USING RESPONSE SURFACE METHODOLOGY

In this study, toluene degradation efficiency and carbon dioxide (CO2) selectivity in a spouted bed reactor with a porous draft tube were optimized using the response surface methodology. For this purpose, titanium dioxide (TiO2) was used as a catalyst for photocatalytic degradation of gaseous toluene in a dynamic mode under ultraviolet (UV) irradiation. The influence of draft tube parameters' (including height, diameter, gap, and porosity) on toluene degradation efficiency and CO2 selectivity (as the response variables) was investigated by central composite design. Analysis of variance (ANOVA) was applied to evaluate the significance of the variables' effects and the interaction between them. Results showed that maximum toluene degradation efficiency of 78.1 % and maximum CO2 selectivity of 88.7 % were obtained at 1.99 cm draft tube height, 1.3 cm draft tube diameter, 1.3 cm gap, and 60 % draft tube porosity. The highest F-values indicated that the gap is the most important variable affecting the toluene degradation efficiency and CO2 selectivity, while the draft tube diameter is the second important variable. The results of experiments at optimal levels of parameters with three replications showed a maximum toluene degradation efficiency of 78.8% (SD= 0.62) and maximum CO2 selectivity of 89.1 % (SD= 0.46). The study revealed that the spouted bed reactor with a porous draft tube has a good stability for volatile organic compounds (VOCs) degradation and mineralization.

Extraction of Value-added Chemicals from Sawdust Bio-oil Through Liquid-liquid Extraction

Bio-oil, a liquid product obtained from pyrolysis of solid biomass, can be used as a sustainable feedstock for the production of renewable fuels and chemicals. Sawdust was used as the feedstock for obtaining bio-oil in conical spouted bed reactor through fast pyrolysis. Liquid-liquid extraction method was used to separate the bio-oil into different chemical groups by their polarities to stabilize bio-oil and improve the quality. Similar oxygen-containing functional groups were present in water and solvent phase of the separated bio-oil. Chloroform, hexane, and petroleum ether were used for the extraction of chemicals from the sawdust bio-oil through liquid-liquid extraction. The solvent phase had high concentrations of organic compounds. With chloroform extraction solvent, 65.89%(w) of organics in water phase were extracted.

Role of Porous and Non-Porous Draft Tube in Photocatalytic Degradation of Toluene in Spouted Bed Reactors

Role of Porous and Non-Porous Draft Tube in Photocatalytic Degradation of Toluene in Spouted Bed Reactors

Oxidative Fast Pyrolysis of High-Density Polyethylene on a Spent Fluid Catalytic Cracking Catalyst in a Fountain Confined Conical Spouted Bed Reactor.

The oxidative fast pyrolysis of plastics was studied in a conical spouted bed reactor with a fountain confiner and draft tube. An inexpensive fluid catalytic cracking (FCC) spent catalyst was proposed for in situ catalytic cracking in order to narrow the product distribution obtained in thermal pyrolysis. Suitable equivalence ratio (ER) values required to attain autothermal operation were assessed in this study, i.e., 0.0, 0.1, and 0.2. The experiments were carried out in continuous regime at 550 °C and using a space-time of 15 gcatalyst min gHDPE -1. The influence of an oxygen presence in the pyrolysis reactor was analyzed in detail, with special focus on product yields and their compositions. Operation under oxidative pyrolysis conditions remarkably improved the FCC catalyst performance, as it enhanced the production of gaseous products, especially light olefins, whose yields increased from 18% under conventional pyrolysis (ER = 0) to 30% under oxidative conditions (ER = 0.1 and 0.2). Thus, conventional catalytic pyrolysis led mainly to the gasoline fraction, whereas light olefins were the prevailing products in oxidative pyrolysis. Moreover, the oxygen presence in the pyrolysis reactor contributed to reducing the heavy oil fraction yield by 46%. The proposed strategy is of great relevance for the development of this process, given that, on one hand, oxygen cofeeding allows solving the heat supply to the reactor, and on the other hand, product distribution and reactor throughput are improved.