Steam/oxygen gasification of dried sewage sludge in a two-stage gasifier: Effects of the steam to fuel ratio and ash of the activated carbon on the production of hydrogen and tar removal

Choi, Young-Kon; Cho, Min-Hwan; Kim, Joo-Sik

doi:10.1016/j.energy.2015.08.027

Cited by 51 publications

(24 citation statements)

References 34 publications

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“…However, no significant decrease in the content of CH 4 was observed, indicating that a high S/B ratio favors the steam reforming of condensable hydrocarbons instead of hydrocarbons with low molecular weight such as methane. A similar trend was reported for steam/oxygen gasification of dried sewage sludge [3]. In Fig.…”

Section: Gas Compositionsupporting

confidence: 67%

Hydrogen-rich gas production by steam gasification of hydrochar derived from sewage sludge

Gai

Guo

et al. 2016

International Journal of Hydrogen Energy

145

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Steam Alkali catalyst Hydrogen Hydrothermal carbonization a b s t r a c tHydrothermal carbonization is an effective pretreatment for further thermal conversion of high moisture biomass without a high cost of a dehydration process. The current paper concerns the properties of hydrochar derived from hydrothermal carbonization of sewage sludge, and the feasibility of steam gasification of hydrochar for hydrogen-rich gas production was investigated. Sewage sludge derived hydrochar was characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and inductively coupled plasma atomic emission spectroscopy to evaluate its feasibility for gasification application. The effect of reaction temperature, steam to biomass mass ratio, and addition of alkali catalysts on steam gasification characteristics of raw sewage sludge and corresponding hydrochar were evaluated, in terms of major composition of the produced gas, gas yield, gasification efficiency and energy density. The results showed that sewage sludge derived hydrochar was rich in hydrophilic functional groups and increased Fe, Ni, alkali and alkaline earth metals (i.e. K, Na, Ca, Mg), resulting in a higher hydrogen yield and energy efficiency than direct steam gasification of sewage sludge under identical conditions. In addition, hydrogen-rich gas production was also favored with the presence of alkali catalysts, especially for the hydrochar. The present study demonstrates that hydrothermal carbonization provides an effective pretreatment of sewage sludge for production of hydrogen-rich gas via steam gasification.

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Section: Gas Compositionsupporting

confidence: 67%

Hydrogen-rich gas production by steam gasification of hydrochar derived from sewage sludge

Gai

Guo

et al. 2016

International Journal of Hydrogen Energy

145

View full text Add to dashboard Cite

show abstract

“…One of the most efficient techniques for tar removal is catalytic steam reforming in which tar compounds can be converted into useful gases and for this purpose various catalysts have been tested [4,[6][7][8]. To cope with the challenges associated with deactivation of commercial catalysts because of coking or sulphur poisoning, char as a by-product obtained in the pyrolysis of organic matter is cheap and easily replaceable and has been found to be effective for tar reforming during the volatile-char interactions [9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Choi et al [14] investigated the gasification of a sewage sludge with the use of activated carbon as a catalyst and reported that the introduction of steam at 800ºC enhanced the steam reforming reactions and produced a free tar syngas with a high content of hydrogen (35-45 vol.%).…”

Section: Introductionmentioning

confidence: 99%

“…The authors attributed the higher activity of coal based activated carbon, among the catalysts used, to its high BET surface area and the large pore size. In another study carried out by Choi et al [14], using original and acid-treated activated commercial carbons, with a BET surface area of 959 m 2 g -1 , were used as tar cracking additives during the steam/oxygen gasification of dried sewage sludge in a two stage gasifier. The acid treated activated carbon was found to be less effective than the original activated carbon, additionally the syngas obtained with the original activated carbon was found to have the highest H2 content.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen-rich syngas production and tar removal from biomass gasification using sacrificial tyre pyrolysis char

2017

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8Carbonaceous materials have been proven to have a high catalytic activity for tar removal from 9 the syngas produced from biomass gasification. The simultaneous reforming and gasification of 10 pyrolysis gases and char could have a significant role in increasing the gas yield and decreasing 11 the tar in the product syngas. This study investigates the use of tyre char as a catalyst for H2-rich 12 syngas production and tar reduction during the pyrolysis-reforming of biomass using a two stage biomass:steam ratio on syngas quality showed that the H2:CO molar ratio was increased from 1.8 24(steam: biomass ratio; 1.82 g g -1 ) to 3 (steam: biomass ratio; 6 g g -1 ). 25

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“…Landfill, incineration and anaerobic digestion are traditional treatments for sewage sludge, which suffer from secondary pollution or long processing period [1]. Gasification appears to be a promising recycling approach for producing renewable hydrogen from sewage sludge in a shorter period of time [2][3][4]. However, one major disadvantage of the gasification of sewage sludge is that a dehydrating treatment is required for the gasification process.…”

Section: Introductionmentioning

confidence: 99%

Effect of Different Thermochemical Pretreatments on Fuel Quality of Sewage Sludge

Liu¹,

Gai²

2017

Proceedings of the 2nd 2016 International Conference on Sustainable Development (ICSD 2016)

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Abstract-Sewage sludge contains large amounts of energy and gasification of sewage sludge may be one of the promising sustainable approaches for hydrogen-rich syngas production from sewage sludge. However, raw sludge is unsuitable for direct gasification and thus pretreatment is necessary to improve its fuel quality prior to further thermal process. In this study, two types of the biochars, pyrochar from low temperature pyrolysis (LTP) and hydrochar from hydrothermal carbonization (HTC) were prepared, characterized and their gasification properties were experimentally evaluated. The results showed that the hydrochar was more hydrophobic than the pyrochar and its surface was rich of oxygen-containing functional groups, which enhanced the interactions between the carbon surface and hydrogen bonding as well as gasification reactivity of the hydrochar under identical conditions. Additionally, the porous structure on the surface of the hydrochar facilitated the pores better accessible for condensable hydrocarbon molecules and the hydrochar had improved gas production and gasification efficiency. This study demonstrates that the integration of HTC pretreatment and subsequent gasification has promising potential for hydrogen-rich syngas production from sewage sludge.

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Steam/oxygen gasification of dried sewage sludge in a two-stage gasifier: Effects of the steam to fuel ratio and ash of the activated carbon on the production of hydrogen and tar removal

Cited by 51 publications

References 34 publications

Hydrogen-rich gas production by steam gasification of hydrochar derived from sewage sludge

Hydrogen-rich gas production by steam gasification of hydrochar derived from sewage sludge

Hydrogen-rich syngas production and tar removal from biomass gasification using sacrificial tyre pyrolysis char

Effect of Different Thermochemical Pretreatments on Fuel Quality of Sewage Sludge

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