CFD analysis of biomass gasification using downdraft gasifier

Pandey, Bhoopendra; Prajapati, Yogesh K.; Sheth, Pratik N.

doi:10.1016/j.matpr.2020.10.451

Cited by 12 publications

(21 citation statements)

References 11 publications

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“…CFD modeling techniques have been widely used for studying the thermal decomposition of biomass under inert , and air/steam conditions. , The CFD tool has been efficiently used in modeling pyrolysis in fluidized bed reactors due to their efficient heat and mass transfer rates along with even product distributions. Xue et al used the Euler–Euler model for the fast pyrolysis of biomass in a fluidized bed reactor.…”

Section: Modeling Approaches To the Pyrolysis Processmentioning

confidence: 99%

Recent Modeling Approaches to Biomass Pyrolysis: A Review

2021

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Biomass pyrolysis is a thermochemical conversion process that undergoes a complex set of concurrent and competitive reactions in oxygen-depleted conditions. A considerable amount of the literature uses lumped kinetic approaches to predict pyrolysis products. Despite the prolonged studies, the science of pyrolysis chemistry and models’ capability to simulate the exact conversion phenomenon has unraveled yet. In this review, an initiative was made by compiling existing mathematical models for biomass pyrolysis viz., lumped and distributed kinetic models, particle, and reactor models. An absolute analysis of computational fluid dynamics (CFD), artificial neural network (ANN), and ASPEN Plus models was also conducted. It was observed that the coupling of distributed kinetic models with CFD provides a better understanding of the hydrodynamic reaction of particles under reactive flow with the influence on reactor performance and predicts exact product yield. Furthermore, the pros and cons of each modeling technique are also highlighted individually. Finally, considering the future perspective of biomass pyrolysis with respect to the modeling approach, suggestions have been incorporated.

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Section: Modeling Approaches To the Pyrolysis Processmentioning

confidence: 99%

Recent Modeling Approaches to Biomass Pyrolysis: A Review

2021

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“…This choice allowed us to investigate atypical combustion conditions of the particles. The temperature in the experiments was 800-1200 • C, which corresponds to the level of temperatures achieved in the downdraft reactors [42][43][44].…”

Section: Combustion Process Parametersmentioning

confidence: 98%

Experimental Study to Replicate Wood Fuel Conversion in a Downdraft Gasifier: Features and Mechanism of Single Particle Combustion in an Inert Channel

Svishchev

2022

Applied Sciences

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Downdraft gasification is a promising process of energy conversion of wood biomass. There are such fuel conversion conditions that differ favorably from conventional conditions. In such conditions, there is no pyrolysis zone in the fuel bed, which precedes the oxidation zone. Fuel is supplied into the oxidizing zone without charring, where it reacts with the intensive cold air flow from tuyeres. The study aims to replicate the conversion of particles in a gasifier close to tuyeres. For this purpose, the individual particles are burned in the muffle furnace space and the quartz channel replicating presence of other bed particles at a first approximation. In the experiment, the furnace temperature was varied, as well as the velocity of air supplied to the particle. Two-stage and single-stage mechanisms of particle combustion were identified. A two-stage process is observed in the range of tuyere velocities below 20 m s−1. The two-stage mechanism is characterized by a stage of devolatilization and volatiles combustion, followed by a stage of char residue combustion. The stages are predominantly separate from each other, and their degree of overlapping is low, amounting to 24%. At the tuyere velocities above 125 m s−1 combustion of particles is realized primarily as a single-stage process. The intensive air flow reaches the fuel particle surface and initiates combustion of the surface char layer. In this case, the stages of devolatilization and char residue combustion run concurrently for the most part. In the single-stage mechanism, the degree of stage overlapping is significantly higher and amounts to 60–95%. For the two-stage combustion mechanism, the effect of cyclic movement of the flame across the particle surface is evident. The number of cycles can reach eight. This effect is due to the change of conversion stages. At air velocity above 95 m s−1, fragmentation of fuel particles commences. A layer of char formed at an initial stage of burning heats up in the intensive air flow and is separated from the particle surface. The heated walls of the quartz channel contribute to the intensification of particle combustion. This effect is probably due to the swirling of the flame between the wall and the particle surface.

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“…However, directly using biomass for energy production is often inefficient due to its low energy density, unwanted moisture content, variability in availability, processing requirements, etc. So, a preferred method is to convert biomass into the desired fuel (user-targeted fuel such as solid fuel-pellets, liquid fuel-ethanol, and chemical transport fuel-hydrogen) [2,3]. Various technologies have been developed, like combustion, gasification, and pyrolysis [4].…”

Section: Introductionmentioning

confidence: 99%

CFDs Modeling and Simulation of Wheat Straw Pellet Combustion in a 10 kW Fixed-Bed Downdraft Reactor

Nath,

Chen,

Bowtell

et al. 2024

Processes

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This research paper presents a comprehensive study on the combustion of wheat straw pellets in a 10 kW fixed-bed reactor through a Computational Fluid Dynamics (CFDs) simulation and experimental validation. The developed 2D CFDs model in ANSYS meshing simulates the combustion process in ANSYS Fluent software 2021 R2. The investigation evaluates key parameters such as equivalence ratio, heating value, and temperature distribution within the reactor to enhance gas production efficiency. The simulated results, including combustion temperature and produced gases (CO2, CO, CH4), demonstrate a significant agreement with experimental combustion data. The impact of the equivalence ratio on the conversion efficiency and lower heating value (LHV) is systematically explored, revealing that an equivalence ratio of 0.35 is optimal for maximum gas production efficiency. The resulting producer gas composition at this optimum condition includes CO (~27.67%), CH4 (~3.29%), CO2 (~11.09%), H2 (~11.09%), and N2 (~51%). The findings contribute valuable insights into improving the efficiency of fixed-bed reactors, offering essential information on performance parameters for sustainable and optimized combustion.

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CFD analysis of biomass gasification using downdraft gasifier

Cited by 12 publications

References 11 publications

Recent Modeling Approaches to Biomass Pyrolysis: A Review

Recent Modeling Approaches to Biomass Pyrolysis: A Review

Experimental Study to Replicate Wood Fuel Conversion in a Downdraft Gasifier: Features and Mechanism of Single Particle Combustion in an Inert Channel

CFDs Modeling and Simulation of Wheat Straw Pellet Combustion in a 10 kW Fixed-Bed Downdraft Reactor

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