Review of supercritical water gasification with lignocellulosic real biomass as the feedstocks: Process parameters, biomass composition, catalyst development, reactor design and its challenges

Lee, Chai Siah; Conradie, Alex; Lester, Edward

doi:10.1016/j.cej.2021.128837

Cited by 105 publications

(47 citation statements)

References 86 publications

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“…As previously mentioned, syngas composition depends on process parameters, reactor design, gasifying agent, type of feedstock and its properties, besides the catalyst, when it is present [8,52]. Two aspects of its composition are particularly important for successfully integrating thermochemical and biochemical technologies, syngas impurities and H 2 /CO ratios [10,23].…”

Section: The Effect Of Syngas Composition On Fermentationmentioning

confidence: 99%

Impacts of Syngas Composition on Anaerobic Fermentation

et al. 2021

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Energy consumption places growing demands on modern lifestyles, which have direct impacts on the world’s natural environment. To attain the levels of sustainability required to avoid further consequences of changes in the climate, alternatives for sustainable production not only of energy but also materials and chemicals must be pursued. In this respect, syngas fermentation has recently attracted much attention, particularly from industries responsible for high levels of greenhouse gas emissions. Syngas can be obtained by thermochemical conversion of biomass, animal waste, coal, municipal solid wastes and other carbonaceous materials, and its composition depends on biomass properties and gasification conditions. It is defined as a gaseous mixture of CO and H2 but, depending on those parameters, it can also contain CO2, CH4 and secondary components, such as tar, oxygen and nitrogenous compounds. Even so, raw syngas can be used by anaerobic bacteria to produce biofuels (ethanol, butanol, etc.) and biochemicals (acetic acid, butyric acid, etc.). This review updates recent work on the influence of biomass properties and gasification parameters on syngas composition and details the influence of these secondary components and CO/H2 molar ratio on microbial metabolism and product formation. Moreover, the main challenges, opportunities and current developments in syngas fermentation are highlighted in this review.

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Section: The Effect Of Syngas Composition On Fermentationmentioning

confidence: 99%

Impacts of Syngas Composition on Anaerobic Fermentation

et al. 2021

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“…On the other hand, clogging can occur because of this phenomenon. It is beneficial to remark here that, in almost the totality of the studies reported on SCWG of industrial feedstock, it is very seldom mentioned that processes had to be interrupted because of clogging of the reactor, stress-related issues, or the reactor leaking [32]. Demonstration scale tests had to be stopped since the fluid flow demonstrated very different behavior from what was expected for the experiments [33].…”

Section: Introductionmentioning

confidence: 98%

“…Such an accumulation may lead to additional pressure build-up and deviation from standard conditions. This may also lead to slow reheating of the reactor after feed entry, which will keep the system away from the set operating conditions and may provoke burst events [32,35].…”

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Implications on Feedstock Processing and Safety Issues for Semi-Batch Operations in Supercritical Water Gasification of Biomass

Blasio

Salierno

Magnano³

2021

Energies

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Biomass with a large amount of moisture is well-suited to be processed by supercritical water gasification, SCWG. The precipitation of inorganics, together with char formation and re-polymerization, can cause reactor plugging and stop the process operations. When plugging occurs, sudden injections of relatively large mass quantities take place, influencing the mass flow dynamics significantly in the process. Reactor plugging is a phenomenon very well observed during SCWG of industrial feedstock, which hinders scale-up initiatives, and it is seldom studied with precision in the literature. The present study provides an accurate evaluation of continuous tubular reactor dynamics in the event of sudden injections of water. An interpretation of the results regarding water properties at supercritical conditions contributes to comprehending mass and heat transfer when plugging occurs. Experiments are then compared to SCWG of a biomass sample aiming to give key insights into heat transfer and fluid dynamics mechanisms that could help develop operational and control strategies to increase the reliability of SCWG. In addition, a simplified model is presented to assess the effect of material integrity on burst-event likelihood, which states that SCWG is safe to operate, at 250 bar and 610 °C, in tubular reactors made of 0.22 wall thickness-to-diameter ratio Inconel-625 with superficial microfractures smaller than 30 µm. We also suggest improvement opportunities for the safety of SCWG in continuous operation mode.

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“…Similarly, there are review articles that deal with different aspects of SCWG, such as model compounds, lignocellulosic or microalgae biomass, types of reactors, energy and exergy, thermodynamics, catalysts, techno-economics, hydrogen production, modeling, and simulation [6][7][8][9][10][11][12][13][14][15][16][17], but there are few references to heat transfer in SCWG processes, especially at the lab scale, which is used most frequently in experimental studies carried out so far. In this regard, the heating rate/time applied to a specific reactor and how heat is transmitted from the energy source to the stream containing organic material and water that suffers a transition from subcritical to supercritical are crucial to understand the phenomena occurring inside the reactor and for scaling up.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Limitations in Supercritical Water Gasification

et al. 2021

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Supercritical water gasification (SCWG) is a promising technology for the valorization of wet biomass with a high-water content, which has attracted increasing interest. Many experimental studies have been carried out using conventional heating equipment at lab scale, where researchers try to obtain insight into the process. However, heat transfer from the energy source to the fluid stream entering the reactor may be ineffective, so slow heating occurs that produces a series of undesirable reactions, especially char formation and tar formation. This paper reviews the limitations due to different factors affecting heat transfer, such as low Reynolds numbers or laminar flow regimes, unknown real fluid temperature as this is usually measured on the tubing surface, the strong change in physical properties of water from subcritical to supercritical that boosts a deterioration in heat transfer, and the insufficient mixing, among others. In addition, some troubleshooting and new perspectives in the design of efficient and effective devices are described and proposed to enhance heat transfer, which is an essential aspect in the experimental studies of SCWG to move it forward to a larger scale.

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Review of supercritical water gasification with lignocellulosic real biomass as the feedstocks: Process parameters, biomass composition, catalyst development, reactor design and its challenges

Cited by 105 publications

References 86 publications

Impacts of Syngas Composition on Anaerobic Fermentation

Impacts of Syngas Composition on Anaerobic Fermentation

Implications on Feedstock Processing and Safety Issues for Semi-Batch Operations in Supercritical Water Gasification of Biomass

Heat Transfer Limitations in Supercritical Water Gasification

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