Fluidized Bed Reactor Research Articles

Bench-Scale Gasification of Olive Cake in a Bubbling Fluidized Bed Reactor

The gasification of olive cake is a promising method for converting this material into valuable energy. This work offers interesting results about the effect of equivalence ratio and temperature on the composition and quality of the produced gas obtained during olive cake gasification in a fluidized bed plant with air as a gasification agent. Additionally, the efficiency of the gasification process was evaluated. The results show that, for a specific temperature, an equivalence ratio of 0.3 showed a higher cold gas efficiency. For example, at 850 °C and an equivalence ratio of 0.1, the cold gas efficiency was 22.7%; however, at the same temperature but at an equivalence ratio of 0.3, the cold gas efficiency was increased to 61.2%. In addition, for a constant equivalence ratio, by increasing the operating temperature, there was no significant increase in the lower heating value of the exit gas, and the gas flow was practically constant with temperature, but it varied substantially with the equivalence ratio, reaching values in the range of 3.44–14.89 NL/min (825.6–3573.6 NL/kg feed). Finally, the production of CO, H2, and CH4 is estimated to be higher for tests conducted with an equivalence ratio of 0.3.

Reaction Characteristics of Calcination and Decomposition of Phosphogypsum in a Bubbling Fluidized Bed.

A bubbling fluidized bed reactor is designed to investigate the high-temperature calcination and decomposition characteristics of phosphogypsum (PG). The reactor employs electric heating, and a lifting discharge tube is installed in the middle of the air distributor to allow flexible switching between batch and continuous feeding modes. The batch test results show that the solid-phase bed materials with a PG particle size of 0.27-0.55 mm and a coal particle size of 0.55-0.83 mm are found to have uniformly mixed at a PG/coal mass ratio of 5:1 and calcined at a high temperature of 1100 °C for 30 min. PG completely decomposes to yield mainly CaS and a small amount of Ca2(SiO4) as the solid-phase products. For the above-mentioned optimal process parameters, a 120 min thermal-state continuous test is conducted. Feeding and discharging are performed at intervals of 30 min to maintain the stability of the static bed height inside the reactor. The results indicate that the PG decomposition rate is higher than 92% in the batch and continuous tests. However, the continuous decomposition of PG has significant process advantages, such as a higher CaS yield (71.20%) compared to that in the batch mode (64.49%). Furthermore, PG undergoes agglomeration and bonding within the particles when heated, intensifying the formation of a Ca2(SiO4) eutectic.

Feasibility of continuous water and carbon dioxide splitting via a pressure-swing, isothermal redox cycle using iron aluminates

Efficient solar thermochemical fuel production has been hindered by either solid–solid heat recuperation and material stability challenges associated with conventional temperature swing operation or low reactant conversion associated with isothermal operation. Increasing the oxidation pressure has emerged as a method for achieving efficient and practical solar-to-fuel conversion with certain redox mediators. When coupled with isothermal operation, pressure-swing redox cycling with iron aluminates eliminates irreversible heating penalties associated with large temperature swings while simultaneously enabling greater reactant conversion. However, remaining questions persist regarding 1) kinetics, 2) co-splitting capabilities, and 3) continuous processing prior to implementation beyond the lab scale. Here, we provide mechanistic insight on how pressure impacts the oxidation kinetics of iron aluminates, demonstrate syngas production with H2:CO ratios ranging from 1.3 ± 0.05 to 3.2 ± 0.25, and produce fuel continuously over an eight-hour period using dual fluidized bed reactors to evaluate the key considerations for large scale implementation. This work demonstrates the feasibility of a continuous solar thermochemical fuel production process via pressure-swing, isothermal redox cycling.

Coke evolution study in a liquid atomization into gas-solid fluidized bed to convert fructose to value-added chemicals

Glucose and fructose are valuable compounds, which have the potential to displace fossil fuels as a feedstock for highly valued products. One of the promising reactions is the oxi-dehydration of fructose to produce Hydroxymethylfurfural, 2,5-diformylfuran, and furfural. Current processes to produce platform chemicals like Hydroxymethylfurfural, furfural, and 2,5-diformylfuran operate in liquid phase with homogeneous heterogeneous catalyst, but commercialization is limited by scale and environmental impact of the large volume solvent required. Here we developed a gas-phase process to convert fructose in a fluidized bed reactor over Mo − V − WO3/TiO2. However, in the catalytic oxi-dehydration of fructose, coke forms on active sites and decreases conversion but increases selectivity. Coke and reactor performance depends on fructose concentration and O2/fructose ratio. In the first 2 h, acidic amorphous coke accumulates (based on TPO, FTIR, and UV–vis). Feeding excess O2 maintains coke in an amorphous structure and liberates oxide sites. Whereas coke promotes, water block active site reducing yield. In this work, we optimized the operating parameters of fructose concentration (%) and O2/fructose ratio, while simultaneously mitigating the issues associated with coke formation and its detrimental effects.

Brine treatment using fluidized bed homogeneous crystallization technology for the simultaneous recovery of calcium and magnesium as dolomite-like granules

Fluidized bed homogeneous crystallization (FBHC) technology is an effective method to treat metal-contained wastewater at ambient temperature and pressure. Seawater desalination is common to produce fresh water and concentrated brine. This highly hardness-contained brine decreases the lifetime of membranes by fouling during desalination process. This study recovers calcium and magnesium by carbonate reagent from synthetic brine wastewater to be dolomite-like particles. The greatest total removal is 90.7 % for calcium and 76.0 % for magnesium, with a crystallization ratio of 89.5 % for Ca and 75.7 % for Mg, using a 40 min of hydraulic retention time, 9.5 of effluent pH, 2.0 of molar ratio, and 24 of reflux ratio. The effluent from the fluidized bed reactor (FBR) is aged in a sedimentation tank for 24 h to increase removal efficiency to 99.98 % for Ca and 84.7 % for Mg. XRD, SEM, FTIR, and Raman analysis reveal that particles are composed of CaCO3·H2O and MgCO3·3H2O with a dolomite-like structure and a core-shell morphology. In a real brine wastewater treatment by FBHC system, 86 % of Ca and 74 % of Mg are crystallized, so disposal costs are 75 % less than those for chemical precipitation, a conventional treating method. Therefore, FBHC technology has high potential to treat hardness-contained brine by reclaiming as dolomite-like granules.

Modeling and optimizing gas solid distribution in fluidized beds

In fluidized bed reactors, uniform distribution of gas and solids is critical to achieve the desired hydrodynamic and kinetic performance. For FCC units, Technip Energies uses a proprietary distributor design to terminate both reactor risers and spent catalyst lift lines to distribute the exiting gas-solid stream into a fluidized bed.In Technip Energies' Resid FCC unit, air and spent catalyst are distributed from an upward flowing stream into a catalyst bed for coke combustion on catalyst. Proper distribution is key to achieve a uniform coke burn and an even temperature profile throughout the bed. In PropyleneMax™ Catalytic Cracking (PMcc™) technology, the reactor riser also terminates in a fluidized bed, requiring proper distribution of the hydrocarbon vapor and solid mixture into the reactor bed, which is key to providing adequate contact for further cracking to valuable products. This paper discusses Technip Energies' gas-solid distribution technology and the recent work performed to develop an improved distributor for use as a riser termination device in both the PMcc reactor and the RFCC regenerator to achieve improved performance. The use of CFD modeling to screen and evaluate the initial concepts and optimize the final selected concept are presented here. The performance matrices used to quantify the benefits of the optimized distributor design with respect to the existing one in the reactor application are highlighted, showing the benefits of improved gas solid distribution on hydrodynamic and kinetic performance. The paper presents a systematic approach to develop a novel industrial device using physics-based computational tools.

Evaluation of the Mineral Manganese OXMN009 and OXMN009P in the Chemical Looping Combustion (CLC) Process Using Thermogravimetry

Indirect combustion with the chemical looping combustion (CLC) of solid oxygen carriers is one of the most promising technologies for capturing carbon dioxide (CO2) in energy production from fossil fuels since the separation of the generated CO2 is inherent to the process itself. Therefore, the cost associated with capturing this gas will be significantly reduced. This technology transfers oxygen from air to fuel through a metal oxide that acts as an oxygen carrier, avoiding direct contact between air and fuel. This oxygen carrier circulates in a fluidized bed reactor called a reduction reactor and an oxidation reactor. (1) This research work has focused on evaluating the behavior of oxygen carriers based on the original and improved manganese mineral (copper-impregnated mineral) named for this study, OXMN009 and OXMN009P, respectively. (2) Equilibrium experiments were carried out on a thermogravimetric balance (TGA) to evaluate the kinetic behavior of these oxygen transporters OXMN009 and OXMN009P, using the gases methane (CH4), carbon monoxide (CO), and hydrogen (H2). (3) The enhanced solid oxygen carrier OXMN009P exhibited good performance for the CLC process with gaseous fuels in terms of reactivity and combustion efficiency, having high reactivity and oxygen transfer properties due to copper impregnation. (4) The results show that OXMN009P has comparable reactivity to other manganese-based materials reported in the literature. It may be an effective option for carbon dioxide capture, as it uses metal oxides as the oxygen transporters (TO). (5) These oxygen transporters, OXMN009 and OXMN009P, are used in a cyclic process that prevents the formation of nitrogen oxides by keeping the air and fuel separate. (6) Thermogravimetric balance (TGA) experiments were conducted to evaluate the kinetic behavior of these copper-modified oxygen transporters. (7) It was found that OXMN009P improved the reactivity and oxygen transfer properties due to copper impregnation. The kinetic parameters obtained in the TGA indicate that the reaction is non-thermal and requires less energy to initiate. (8) The results show that OXMN009P has reactivity comparable to other manganese-based materials reported in the literature and can be an effective option for carbon dioxide capture.

Performance of a perovskite-structured calcium manganite oxygen carrier produced from natural ores in a batch reactor and in operation of a chemical-looping combustion reactor system

The potential for low cost of CO2 capture using chemical-looping combustion (CLC) should not be compromised by costs associated with the oxygen carrier. This justifies studies of oxygen carrier materials with reasonable production costs. In this study, a perovskite calcium manganite (CaMnO3-δ), was synthesized from manganese ore and limestone through a straightforward process involving mixing with polyvinyl-alcohol, sintering, crushing and sieving. The calcium manganite produced exhibited two primary crystalline phases: CaMnO3 (perovskite) and CaMn2O4 (marokite). Experiments were conducted using both a batch fluidized-bed reactor and a 300 W CLC reactor system in continuous operation to assess the oxygen uncoupling and reactivity of the calcium manganite. The results show that the oxygen uncoupling ability increases with temperature. Full syngas conversion was achieved at relatively low temperatures and low fuel-reactor bed mass over fuel power ratio in the 300 W unit. Elevated temperatures and ratio of fuel-reactor bed mass over fuel power enhance methane conversion significantly. The attrition of the calcium manganite was low, around 0.1 wt%/h for the last 15 h operation with methane. Batch reactor tests of fresh and used materials showed that there was no reduction in reactivity after 29 h of fuel operation.

Hydrogen Production from Natural Gas Using Hot Blast Furnace Slag: Techno-economic Analysis and CFD Modeling

A process for thermal decomposition of methane to hydrogen and solid carbon is presented and examined. It utilizes the high-temperature heat from the slag by-product of blast furnace ironmaking to drive a thermal decomposition reaction, making it a waste-heat-to-hydrogen technology. This is accomplished via dry granulation of molten slag that feeds a fluidized bed reactor to effect methane–slag contact. First, the proposed process and the heat and mass balances are presented. It is found that it could produce an amount of hydrogen that is equivalent to about 20% of the reductant, depending on the iron-to-slag ratio. Then, a techno-economic analysis investigates the capital and operating costs of the process, compares the hydrogen production cost to that of other processes, and examines cost sensitivity to the prices of process inputs and outputs. This analysis suggests that the process would be suitable for on-site hydrogen production and use within a plant. In addition, using the hot slag to drive the methane decomposition would reduce hydrogen production cost by 15% compared to combusting a portion of the natural gas itself. Finally, a computational fluid dynamics (CFD) modeling study of the fluidized bed reactor examines the thermal decomposition of methane and its dependence on reaction kinetics as well as reactor design and operation. The bed operated in the bubbling regime at an average temperature between 1020 and 1060 °C and resulted in as high as 82% conversion of the methane to hydrogen, with additional optimization still possible.Graphical

Synergizing sugarcane waste valorization: Optimization of two-stage anaerobic co-digestion for enhanced methane recovery and organic matter removal

Multiple strategies have been used in anaerobic digestion of effluents aiming to enhance the efficiency of the methane (CH4) recovery process, where co-digestion and the two-stage process emerge as prominent methods. In this context, this study aimed at evaluating the co-digestion of sugarcane vinasse and molasse in a two-stage process using anaerobic fluidized bed reactors (AFBR), verifying the effect of increasing the organic loading rate (OLR) (5–22.5 kg COD.m−3.d−1) and temperature in the second stage methanogenic reactor. Regarding the two-stage process, sugarcane vinasse and molasses fermentation demonstrated the maximum energy potential (E.P) of 57.08 kJ.d−1 (7.5 g COD.L−1). Regarding the methanogenic sequential reactors, organic matter removal reached high values (up to 84.5 % in a thermophilic sequential reactor (TSR); up to 84.5 % in a mesophilic sequential reactor (MSR)). The highest CH4 yield (MY) of 306.77 ± 38.84 mL CH4.g−1 COD rem was observed in MSR (9 kg COD.m−3.d−1). Meanwhile, the maximum value of MPR (3.8 ± 0.5 L CH4.L−1.d−1) was observed in TSR (21 kg COD.m−3.d−1). Regarding the Archaea domain, a predominance of hydrogenotrophic microorganisms could be identified, in which the genera Methanobacterium and Methanothermobacter were the most abundant in MSR and TSR, respectively. This study demonstrates that anaerobic digestion of sugarcane vinasse and molasses enhances anaerobic treatment using two-stage AFBRs. It not only produces CH4 but also generates hydrogen and high-value products through an acidogenic reactor. This research marks a significant advancement in managing sugarcane processing by-products, offering promising approaches to maximize biogas production and improve pollutant removal efficiency.

Quantitative Correlation Analysis of Mixing and Circulation Characteristics in a Liquid-Containing Gas–Solid Fluidized Bed Reactor under Coupled Effects of Multiple Parameters

Quantitative Correlation Analysis of Mixing and Circulation Characteristics in a Liquid-Containing Gas–Solid Fluidized Bed Reactor under Coupled Effects of Multiple Parameters

Ideal performance assessment of non-recirculating anaerobic fluidized bed reactors treating low to high strength organic loads with low retention time

This study investigated the ideal performance of non-recirculating Anaerobic Fluidized Bed Reactors (AnFBRs) for treating organic wastewater of varying strengths under low Hydraulic Retention Time (HRT). Four 4.58 L AnFBRs were used to treat synthetic wastewater with an Organic Loading Rate (OLR) ranging from 4.50 to 40.11 gCOD/L-d, and HRT between 1.1 and 4.4 hours. The AnFBRs achieved high removal efficiencies ranging from 83 % to 96 % at steady state, except during the organic shock load, which reduced removal performance to 12 %. Shortened HRT conditions led to a decreasing trend in reactor pH due to an incomplete anaerobic cycle. The modified Stover-Kincannon model estimated the maximum substrate utilization rate of AnFBR's to be 196.08 gCOD/L-d, with a correlation coefficient of 0.98. Under shortended HRT, microbial diversity analysis identified predominant non-filamentous bacterial families, such as Streptococcaceae and Veillonellaceae, which collaborate during biofilm development in anaerobic environments. It was suggested that the porous media provided secure attachment sites for the biomass growth and biofilm formation under shock load and high shear force conditions. While these results offer valuable insights, further studies are needed to confirm these findings and enhance the understanding of the use porous media in non-recirculating AnFBRs.

Experimental study and correlation analysis for the effect of hydrogen pressure on biomass fluidized hydropyrolysis under N2-H2 mixed atmosphere

The utilization of fluidized bed reactors for the biomass hydropyrolysis vapor upgrading is essential in the conversion of biomass into liquid fuels. Conducting pyrolysis experiments in fluidized bed reactors with a N2-H2 mixed atmosphere is advantageous for system operation as it allows for lower minimum operating velocities, enhances pyrolysis efficiency, and reduces heat loss. This research examines the impact of hydrogen pressure in a bubbling fluidized bed reactor using a N2-H2 mixed carrier gas, with poplar wood as the feedstock and Ni-Moγ/Al2O3 as the catalyst. Through experimental and correlation analyses, significant relationships are observed between hydrogen pressure and the production of liquid and gas-phase products, with varying effects attributed to changes in hydrogen ratio and reaction pressure. Elevated hydrogen ratios facilitate secondary reactions such as the CO2 hydrogenation, resulting in a decline in CO2 production and an elevation in the yields of light hydrocarbons and aqueous phase products. Augmenting the reaction pressure to enhance hydrogen pressure aids in promoting hydrogen saturation and cracking, and amplifying the hydrogen pressure through an increase in the reaction pressure at a specific hydrogen ratio proves more efficacious in enhancing both the quantity and quality of bio-oil produced. In the context of poplar hydropyrolysis vapor upgrading utilizing a Ni-Moγ/Al2O3 catalyst, a hydrogen ratio of 50 % at a reaction pressure of 1.5 MPa emerged as the preferred option for achieving a 12 % bio-oil yield with a moderate average bio-oil carbon number and satisfactory hydrogenation levels. This comprehensive investigation examines the influence of hydrogen pressure on biomass hydropyrolysis, highlighting variations in the impacts of changes in hydrogen ratio and reaction pressure on pyrolysis results. These results offer a theoretical framework for discerning distinctions between hydropyrolysis investigations carried out in pure hydrogen atmospheres versus mixed N2-H2 atmospheres.

Catalytic Cracking of Crude Waste Plastic Pyrolysis Oil for Enhanced Light Olefin Production in a Pilot-Scale Circulating Fluidized Bed Reactor

Catalytic Cracking of Crude Waste Plastic Pyrolysis Oil for Enhanced Light Olefin Production in a Pilot-Scale Circulating Fluidized Bed Reactor

Preparation and characterization of adsorbents in a CO2 hydrogenation process with a fluidized bed reactor for the synthesis of methanol

El estudio se centra en la evaluación de varios adsorbentes para su aplicación en un proceso de hidrogenación de CO2 en un reactor de lecho fluidizado para la síntesis de metanol. Para ello, se realizan pruebas de adsorción de vapor de agua a diferentes condiciones y se obtienen sus respectivas curvas de adsorción.

Thermodynamic and Economic Analyses of a Novel Cooling, Heating and Power Tri-Generation System with Carbon Capture

The combined cooling, heating, and power (CCHP) system has attracted increasing attention due to its potential outstanding performance in thermodynamics, economics, and the environment. However, the conventional CCHP systems are carbon-intensive. To solve this issue, a low-carbon-emission CCHP system (LC-CCHP) is firstly proposed in this work by integrating a sorption-enhanced steam methane reforming (SE-SMR) process. In the LC-CCHP system, CO2 is continuously captured by the calcium loop so that low-carbon energy can be generated. Then, the LC-CCHP system thermodynamic model, mainly consisting of a dual fluidized bed reactor which includes the SE-SMR reactor and a CaCO3 calcination reactor, a hydrogen gas turbine, a CO2 reheater, and a lithium bromide absorption chiller, is built. To prove that the LC-CCHP model is reliable, the system major sub-unit model predictions are compared against data from the literature in terms of thermodynamics and economics. Finally, the effects of reforming temperature (Tref), the steam-to-carbon mole ratio (S/C), the calcium-to-carbon mole ratio (RCC), the equivalent ratio for gas turbine (RAE), and the hydrogen separation ratio (Sfg) on total energy efficiency (ηten), total exergy efficiency (ηtex), and carbon capture capability (Rcm) are detected. It is found that the minimum exergy efficiency of 64.5% exists at the calciner unit, while the maximum exergy efficiency of 78.7% appears at the gas turbine unit. The maximum energy efficiency and coefficient of performance of the absorption chiller are 0.52 and 1.33, respectively. When Tref=600 °C, S/C=4.0, RCC=7.62, RAE=1.20, and Sfg=0.27, the ηten, ηtex, and Rcm of the system can be ~61%, ~68%, and ~96%, and the average specific cost of the system is 0.024 USD/kWh, which is advanced compared with the parallel CCHP systems.

Direct production of olefins from waste plastic using a pyrolysis and fluid catalytic cracking integrated process: Part 1. study on the production and analysis of waxy oil obtained using a new type of a fluidized bed reactor

The ultimate aim of this research is to produce ethylene and propylene directly from waste plastic. To achieve this, we designed a new cracker having a fluidized bed reactor (FBR) and a fluid catalytic cracking (FCC) unit. The FBR produces oil in vapor phase, and the FCC unit transforms the vapor into olefins. As a first step toward achieving the research goal, the current study conducts pyrolysis of low-density polyethylene using a new pyrolysis process having a FBR. By understanding characteristics of pyrolysis oils obtained in this study, it becomes possible to determine its suitability as FCC feed and its relationship with olefin productivity. The current investigation focused on the effects of vapor residence time, reaction temperature, and type of fluidizing medium on yield and composition of oil. The results showed that the waxy oil yield depended highly on reaction temperature, reaching a maximum of about 95 wt%. The sum of yields of n-alkenes and n-alkadienes, which are favorable for producing olefins when catalytically cracked in the FCC unit, reached 82 wt%. SIMDIS analysis, which determines the boiling point range distribution of oil, revealed strong effects of reaction temperature and residence time on the carbon numbers of the waxy oil.

Experimental investigation of aerodynamic behavior of wood chips in fluidized bed reactors as a sustainable biomass fuel

Sustainable energy solutions are necessary in the current manufacturing advancements, where a need is being pressed upon biomaterial-based processes. This study examines the aerodynamics of wood chip biomass in fluidized-bed reactors, an essential aspect of sustainable biomass fuel technologies. Through experimental investigations, the current methodology determined the minimum fluidization rates for particles of four distinct sizes and compared these with theoretical prediction-based calculations. A novel laboratory setup featuring a Differential Pressure Feedback Exhaust gas recirculation (DPFE) sensor system was developed to measure these processes continuously to advance the enhancements of the precision and reliability of the findings. Key results include the successful adaptation of the Ergun equation for wood chips, herewith accommodating observed deviations in pressure drops within specific fluidization ranges. This adaptation, along with real-time data tracking of air phase changes using a multifunction measuring device, revealed critical insights into turbulence patterns and particle movement. These results and findings are consistent with theoretical models and underscore the potential to optimize wood chip use in fluidized-bed reactors. The study's results also contribute significantly to the field of renewable energy as they offer a validated methodological approach and practical modifications to existing theoretical models.

An Industrial Perspective for Sustainable Polypropylene Plastic Waste Management via Catalytic Pyrolysis—A Technical Report

Recycling plastics on an industrial scale is a key approach to the circular economy. This study presents a techno-economic analysis aimed at recycling polypropylene waste, one of the main consumer plastics. Specifically, it evaluates the technical and economic feasibility of achieving a large-scale cracking process that converts polypropylene waste into an alternative fuel. Pyrolysis is considered as a promising technique to convert plastic waste into liquid oil and other value-added products, with a dual benefit of recovering resources and providing a zero-waste solution. This study concerns a fast catalytic pyrolysis in a fluidized bed reactor, with the presence of a fluid catalytic cracking catalyst of low acidity for high heat transmission, for an industrial plant with a capacity of 1 t/h of polypropylene waste provided by the Greek Petroleum Industry. From the international literature, the operational conditions were chosen pyrolysis temperature at 430 °C, pressure at 1atm, heating rate at 5 °C/min, and yields of products to 71, 14, and 15 wt.%, for liquid fuel, gas, solid product, respectively. The plant design includes a series of apparatuses, with the main one to be the pyrolyzer. The catalytic method is selected over the non-catalytic because the presence of catalyst increases the quantity and quality of the liquid product, which is the main product of the plant. The energy loops of recycling pyrolysis gas and char as a low-carbon fuel in the plant were considered. The production cost, annual revenue, for 2023, are anticipated to reach €13.7 million (115 €/t) and €15 million (15 €/t), respectively, with an estimated investment equal to €5.3 million. The Payback Time is estimated to 2.4 years to recover the cost of investment. The endeavor is rather economically sustainable. A critical parameter for large scale systems is securing feedstock with low or negligible price.

Iron Catalyzed Methane Pyrolysis in a Stratified Fluidized Bed Reactor

Iron Catalyzed Methane Pyrolysis in a Stratified Fluidized Bed Reactor