An Assessment of Operating Conditions for Supercritical Water Gasification and Safety Issues

Nickel iron oxide (NiFe2O4) catalyst was prepared by the combustion reaction method and characterized by XRD, N2 adsorption/desorption, thermogravimetric analysis (TG), and temperature programmed reduction (TPR). The catalyst presented a mixture of oxides, including the NiFe2O4 spinel and specific surface area of 32.4 m2 g−1. The effect of NiFe2O4 catalyst on the supercritical water gasification (SCWG) of eucalyptus wood chips was studied in a batch reactor at 450 and 500 °C without catalyst and with 1.0 g and 2.0 g of catalyst and 2.0 g of biomass for 60 min. In addition, the recyclability of the catalyst under the operating conditions was also tested using recovered and recalcined catalysts over three reaction cycles. The highest amount of H2 was 25 mol% obtained at 450 °C, using 2 g of NiFe2O4 catalyst. The H2 mol% was enhanced by 45% when compared to the non-catalytic test, showing the catalytic activity of NiFe2O4 catalyst in the WGS and the steam reforming reactions. After the third reaction cycle, the results of XRD demonstrated formation of coke which caused the deactivation of the NiFe2O4 and consequently, a 13.6% reduction in H2 mol% and a 5.6% reduction in biomass conversion.

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

Energies ◽

10.3390/en14102863 ◽

2021 ◽

Vol 14 (10) ◽

pp. 2863

Author(s):

Cataldo De Blasio ◽

Gabriel Salierno ◽

Andrea Magnano

Keyword(s):

Heat Transfer ◽

Supercritical Water ◽

Control Strategies ◽

Operation Mode ◽

Scale Up ◽

Tubular Reactor ◽

Large Mass ◽

Inconel 625 ◽

Safety Issues ◽

Supercritical Water Gasification

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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Finding appropriate operating conditions for hydrogen purification and recovery in supercritical water gasification of biomass

Chemical Engineering Journal ◽

10.1016/j.cej.2006.08.001 ◽

2006 ◽

Vol 124 (1-3) ◽

pp. 7-13 ◽

Cited By ~ 11

Author(s):

Peijun Ji ◽

Wei Feng ◽

Biaohua Chen ◽

Qipeng Yuan

Keyword(s):

Supercritical Water ◽

Operating Conditions ◽

Hydrogen Purification ◽

Supercritical Water Gasification

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Supercritical water gasification of food waste: Effect of parameters on hydrogen production

International Journal of Hydrogen Energy ◽

10.1016/j.ijhydene.2020.03.190 ◽

2020 ◽

Vol 45 (29) ◽

pp. 14744-14755 ◽

Cited By ~ 3

Author(s):

Wei Su ◽

Changqing Cai ◽

Ping Liu ◽

Wei Lin ◽

Baorui Liang ◽

...

Keyword(s):

Hydrogen Production ◽

Food Waste ◽

Supercritical Water ◽

Supercritical Water Gasification

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Graphene-supported metal nanoparticles as novel catalysts for syngas production using supercritical water gasification of microalgae

Biomass and Bioenergy ◽

10.1016/j.biombioe.2018.11.035 ◽

2019 ◽

Vol 121 ◽

pp. 13-21 ◽

Cited By ~ 6

Author(s):

Roudabeh Samiee-Zafarghandi ◽

Alireza Hadi ◽

Javad Karimi-Sabet

Keyword(s):

Metal Nanoparticles ◽

Supercritical Water ◽

Syngas Production ◽

Supercritical Water Gasification ◽

Supported Metal Nanoparticles ◽

Supported Metal

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Supercritical water gasification (SCWG) as a potential tool for the valorization of phycoremediation-derived waste algal biomass for biofuel generation

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2021.126278 ◽

2021 ◽

pp. 126278

Author(s):

Yoong Kit Leong ◽

Wei-Hsin Chen ◽

Duu-Jong Lee ◽

Jo-Shu Chang

Keyword(s):

Supercritical Water ◽

Algal Biomass ◽

Supercritical Water Gasification ◽

Potential Tool

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Gasification of Biomass in Supercritical Water, Challenges for the Process Design—Lessons Learned from the Operation Experience of the First Dedicated Pilot Plant

Processes ◽

10.3390/pr9030455 ◽

2021 ◽

Vol 9 (3) ◽

pp. 455

Author(s):

Nikolaos Boukis ◽

I. Katharina Stoll

Keyword(s):

Organic Matter ◽

Supercritical Water ◽

Process Design ◽

Pilot Plant ◽

Lessons Learned ◽

Present Contribution ◽

Flow Process ◽

Combustible Gas ◽

Supercritical Water Gasification ◽

Robust Process

Gasification of organic matter under the conditions of supercritical water (T > 374 °C, p > 221 bar) is an allothermal, continuous flow process suitable to convert materials with high moisture content (<20 wt.% dry matter) into a combustible gas. The gasification of organic matter with water as a solvent offers several benefits, particularly the omission of an energy-intensive drying process. The reactions are fast, and mean residence times inside the reactor are consequently low (less than 5 min). However, there are still various challenges to be met. The combination of high temperature and pressure and the low concentration of organic matter require a robust process design. Additionally, the low value of the feed and the product predestinate the process for decentralized applications, which is a challenge for the economics of an application. The present contribution summarizes the experience gained during more than 10 years of operation of the first dedicated pilot plant for supercritical water gasification of biomass. The emphasis lies on highlighting the challenges in process design. In addition to some fundamental results gained from comparable laboratory plants, selected experimental results of the pilot plant “VERENA” (acronym for the German expression “experimental facility for the energetic exploitation of agricultural matter”) are presented.

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