Real-time performance investigation of a downdraft gasifier fueled by cotton stalks in a batch-mode operation

Rabea, Karim; Bakry, Ayman I.; Khalil, A.; El-Fakharany, Magda K.; Kadous, Mahmoud

doi:10.1016/j.fuel.2021.120976

Cited by 20 publications

(5 citation statements)

References 29 publications

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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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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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“…The annual output of rice and straw in Vietnam reaches 97 million tons, and its energy potential exceeds 380 Twh (Beňová et al 2021). Many countries have gradually found that agricultural biomass can be used as a substitute for traditional fuels, offering a way to reduce the net amount of pollution caused by incineration (Bot et al 2021;Rabea et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Sustainable conversion of agricultural biomass into renewable energy products: A Discussion

Zhou

Yang

et al. 2022

BioRes

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This paper discusses the use of agricultural biomass as a promising resource for renewable energy production, e.g., bio-oil and biogas via pyrolysis and catalysis, among other technologies. In order to prevent the accumulation of agricultural biomass, most countries still use traditional disposal or processing methods, e.g., burning in the field, which not only has a low energy conversion rate, but also releases harmful gases, e.g., CO2, CO, and NH3. These traditional methods are regarded as inefficient with respect to the low utilization of waste; they also pose a threat to human health. The energy conversion of agricultural biomass makes full use of resources and accelerates the development of green energy. In particular, agricultural biomass can lead to the production of high-quality renewable fuels and chemical raw materials through catalytic pyrolysis technologies. The fuel produced using catalytic pyrolysis has a low sulfur and alkali metal contents and techno-economic analysis shows that catalytic pyrolysis greatly reduces the production cost and improves the utilization rate of agricultural biomass. The production of bio-oil and gas via catalytic pyrolysis and agricultural biomass are environmentally friendly and economically feasible for clean energy production. Therefore, additional research is needed to enable the upscaling of renewable energy products.

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“…Therefore, it is expected that in the coming years, the importance of biomass and development of the systems for utilization of biomass will increase remarkably. Thermochemical conversion reduces the inherent disadvantages of solid biomass such as processing, storage and low energy density (Rabea et al, 2021). It is well known that the most efficient thermochemical method for converting biomass into energy is gasification.…”

Section: Introductionmentioning

confidence: 99%

“…Combustible syngas is a mixture of oxygen (O2), nitrogen (N2) and ash residues with carbon dioxide (CO2) as well as methane (CH4), carbon monoxide (CO), hydrogen (H2) and small amounts of light hydrocarbons (Karatas et al, 2013). The concentrations of these components in the syngas determine the effectiveness and quality of the whole conversion process (Rabea et al, 2021). The most important parameters for evaluating biomass gasification performance are the cold gas yield, lower calorific value and the volume of syngas per unit weight of biomass (Guo et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Investigation of Oak Wood Biochar Gasification in Downdraft Gasifier Using Aspen Plus Simulation

Sezer¹,

Fuçucu²,

Özveren³

2021

bes

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In response to increasing energy demands and the inevitable release of greenhouse gases into the environment, researchers have turned their attention to biomass energy production. Biomass offers a lot of benefits; however, it has poor calorific value due to its higher moisture and volatile content. Carbonization can be used to overcome this disadvantage and produce biomass with a higher carbon content. One of the most promising thermochemical conversion techniques is gasification. In this study, biochar from oak wood was gasified in a steam environment using Aspen Plus® simulation. The downdraft gasifier model was developed under steady-state equilibrium parameters based on the minimization of Gibbs free energy. As consistent with the literature, H2 was produced higher amount in the steam gasification (55.65%) compared with the air gasification (17.36%). Parametric analyzes were performed to investigate the influence of the operating parameters on the composition of the syngas. Results depicted that the increasing temperature and steam/biochar ratio raised the H2 concentration from 53.21% to 55.72% and 54.50% to 56.84% in syngas respectively. Temperature also showed positive influence on the LHV of syngas that changed between 19620-19708 kJ/kg. The steam/biochar ratio affected the LHV of syngas negatively thus it decreased from 20257 to 18777 kJ/kg.

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Real-time performance investigation of a downdraft gasifier fueled by cotton stalks in a batch-mode operation

Cited by 20 publications

References 29 publications

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

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

Sustainable conversion of agricultural biomass into renewable energy products: A Discussion

Investigation of Oak Wood Biochar Gasification in Downdraft Gasifier Using Aspen Plus Simulation

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