The case of Frictional Torrefaction and the effect of reflux condensation on the operation of the Rotary Compression Unit

Vakalis, Stergios; Heimann, R.L.; Ahmad, Jamal; Patuzzi, Francesco; Baratieri, Marco

doi:10.1016/j.biortech.2018.07.140

Cited by 10 publications

(4 citation statements)

References 33 publications

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“…The positive effect of conventional steam explosion on the final char yield has also been reported by other studies as well. 26 Except the effect of steam on the final char yield, the effect of steam explosion on the porosity has been investigated and the results were moderate for the case of frictional treatment, 27 conventional steam explosion treatment and torrefaction 28 and the pyrolysis of lignin. 29 A critical parameter that should be denoted is that in the case of frictional pyrolysis, the steam medium evolved from the moisture in the biomass and thus the role of moisture in thermochemical processes needs further inspection.…”

Section: Introductionmentioning

confidence: 99%

Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO₂ gasification

Ahmad

Vakalis

Patuzzi

et al. 2020

Energy & Environment

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Biomass char is defined as the carbonaceous by-product of biomass pyrolysis or gasification and is an undesired by-product that is disposed as a waste, usually at a very high cost. Chars have interesting characteristics like high carbon content and high porosity. These characteristics can make attractive the utilization of biomass char for alternative and innovative applications, e.g. as precursors for activated carbons or as filtering mediums. In this framework, this present work focuses the attention on the surface properties of char which is a key parameter for the evaluation of its applicability in adsorption applications. The combination of three main variables has been considered: the carrier gas (nitrogen or carbon dioxide), the temperature (set at 500°C, 700°C and 900°C) and the initial heating rate (10°C min−1, 30°C min−1 or 50°C min−1). Maximum heating values are observed at 700°C for the case of inert atmosphere (pyrolysis) and the values reduce slightly for the case of CO2 gasification. On the contrary, CO2 gasification has a positive effect on the porosity of the biomass chars. This present research has the scope to provide a first insight on the effect of operating conditions on the optimal char characteristics for the utilization of biomass char as a cheap alternative for filters and adsorbents. An interesting future potential transition of existing biomass CHP facilities would be the evolution into biorefineries, in accordance with the new mandates about Circular Economy.

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Section: Introductionmentioning

confidence: 99%

Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO₂ gasification

Ahmad

Vakalis

Patuzzi

et al. 2020

Energy & Environment

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“…Furthermore, the emissions of greenhouse gases disrupt the growth environment for animals and plants, leading to ecological imbalances and presenting a formidable challenge to species diversity. Consequently, the development of technology for the capture, storage, transformation, and utilization of CO 2 has become a shared concern within the contemporary scientific community (Vakalis et al 2018).…”

Section: Graphical Abstract 1 Introductionmentioning

confidence: 99%

Variable frequency microwave induced CO2 Boudouard reaction over biochar

Ren,

Jiang,

Wang

et al. 2024

Biochar

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The Boudouard reaction presents promising application prospects as a straightforward and efficient method for CO2 conversion. However, its advancement is hindered primarily by elevated activation energy and a diminished conversion rate. This study employed a microwave reactor with a variable frequency as the initial approach to catalyze the CO2 Boudouard reaction over biochar, with the primary objective of producing renewable CO. The study systematically investigated the influence of various variables, including the heating source, microwave frequency, microwave power, gas hourly space velocity (GHSV), and carrier gas, on the conversion of CO2 and the selectivity towards CO. The experimental findings indicate that under static conditions, with a fixed microwave frequency set at 2450 MHz and 100 W microwave power, the Boudouard reaction did not initiate. Conversely, a CO2 conversion rate of 8.8% was achieved when utilizing a microwave frequency of 4225 MHz. Under this unique frequency, further elevating the microwave power to 275 W leads to the complete conversion of CO2. Furthermore, a comparative analysis between microwave and electrical heating revealed that the CO production rate was 37.7 μmol kJ−1 for microwave heating, in stark contrast to the considerably lower rate of 0.2 μmol kJ−1 observed for electric heating. Following the reaction, the biochar retained its robust 3D skeleton structure and abundant pore configuration. Notably, the dielectric constant increased by a factor of 1.8 compared to its initial state, rendering it a promising microwave-absorbing material. Graphical Abstract

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“…This approach appears to be promising for using novel carbonaceous products in co-digestion processes. Investigating the pathway of biochar production, it is straightforward that it can be produced from pyrolysis of carbon-rich feedstock of relatively low-moisture [18]. Thus, material with high water content, like the available biowaste in Lesvos Island cannot be treated conventionally with thermal technologies, except if excessive amounts of energy are utilized for drying the material.…”

Section: Introductionmentioning

confidence: 99%

Hydrothermal Carbonization of Dry Anaerobic Digestion Residues derived from Food and Agro Wastes in Lesvos Island

Xypolias¹,

Vakalis²,

Daskaloudis³

et al. 2023

Preprint

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Biowaste management is in the center of attention in recent years, due to the increased focus on Circular Economy practices. Recent management solutions promote exploration for small and medium scale processing and monitoring practices. In this context, two pathways of biowaste valorization are analyzed: composting and anaerobic digestion. This study focuses on energy production with the hydrothermal carbonization (HTC) of anaerobic residues from biogas production. Lesvos has numerous processing facilities and olive mills, and therefore Olive Mill Wastewater (OMWW) are the main biowaste streams in the island, along with olive tree pruning, the organic fraction of municipal solid waste and sludge from wastewater treatment facilities. Most studies present applications on specific types of biowaste, while this study aims to co-treat several biowaste streams. A holistic experimental set-up that combines aerobic and anaerobic treatment strategies was developed taking into consideration the hydrothermal treatment of AD digestate along with locally available biowaste, like OMWW, sludge etc. A main target objective is to investigate if solid fraction could have a high heating potential In addition, HTC was able significantly to reduce the COD of OMWW while resulting in hydrochars with increased heating values.

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The case of Frictional Torrefaction and the effect of reflux condensation on the operation of the Rotary Compression Unit

Cited by 10 publications

References 33 publications

Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO₂ gasification

Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO₂ gasification

Variable frequency microwave induced CO2 Boudouard reaction over biochar

Hydrothermal Carbonization of Dry Anaerobic Digestion Residues derived from Food and Agro Wastes in Lesvos Island

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The case of Frictional Torrefaction and the effect of reflux condensation on the operation of the Rotary Compression Unit

Cited by 10 publications

References 33 publications

Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO2 gasification

Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO2 gasification

Variable frequency microwave induced CO2 Boudouard reaction over biochar

Hydrothermal Carbonization of Dry Anaerobic Digestion Residues derived from Food and Agro Wastes in Lesvos Island

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Product

Resources

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Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO₂ gasification

Effect of process conditions on the surface properties of biomass chars produced by means of pyrolysis and CO₂ gasification