Effect of pressure on tar decomposition activity of different bed materials in biomass gasification conditions

Tuomi, Sanna; Kaisalo, Noora; Simell, Pekka; Kurkela, Esa

doi:10.1016/j.fuel.2015.05.051

Cited by 38 publications

(22 citation statements)

References 29 publications

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“…Nonetheless, the inherent advantages of pressurized gasification are equally counterbalanced by its drawbacks. For many pressurized gasification projects, the operational challenges related to the complexity of the system, its construction and control have ultimately led to various failures, unstable operation or lack of economical ground for the investment [6]. For coal, gasification at pressures higher than 50 bar is supported by the increase in reaction kinetics and thus the whole installation concept is justified.…”

Section: Introductionmentioning

confidence: 99%

Influence of pressure and CO2 in fluidized bed gasification of waste biomasses

Szul¹,

Głód²,

Iluk³

2020

Biomass Conv. Bioref.

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An autothermal fluidized bed reactor was used to research the influence of pressure (0–2 barg) on the gasification process of different types of biomasses. The tested feedstocks were bark and lignin while softwood pellet was used as a reference fuel. A mixture of O2/CO2/H2O was used as a gasification agent. The impact of the application of CO2 on the yield of H2 in product gas was determined. Resulting product gas was characterized by a high content of CO which makes its use for applications based on chemical synthesis very difficult without extensive upgrading or supply of H2 from external sources. CO2 proved to improve carbon conversion efficiency (CCE) of the gasification process and to be an option for its chemical sequestration (negative carbon footprint). A slight modification of conventional indices used to evaluate efficiencies of gasification systems (CCE and water/carbon ratio) was proposed, to take into account the impact of the additional source of carbon fed into the reactor. The increase of system pressure led to changes in the composition of the product gas in line with predictions of Le Chatelier’s principle. The influence was predominantly visible in higher yields of CH4 and lower overall production of product gas. For higher hydrocarbons (CxHy), the trend was unclear. A set of stable gasification parameters were achieved for each pressure level and a standard gasification temperature of 850 °C, except for gasification of lignin performed at 2 barg. A proposed explanation for the problem is the combined effect of the increasing concentration of ash in the fluidized bed and its low characteristic melting temperatures. Due to the obtained experimental findings, a new ash agglomeration index was formulated.

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Section: Introductionmentioning

confidence: 99%

Influence of pressure and CO2 in fluidized bed gasification of waste biomasses

Szul¹,

Głód²,

Iluk³

2020

Biomass Conv. Bioref.

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“…Gasification model. To validate the gasification model, experiments from different references 16,[33][34][35][36][37][38][39] were simulated, each under its own set of conditions (e.g. biomass composition, gasification temperature, equivalence ratio, etcetera).…”

Section: Model Validationmentioning

confidence: 99%

“…biomass composition, gasification temperature, equivalence ratio, etcetera). The experiments simulated for validation included fluidised bed gasifiers 16,33,36,37 and downdraft gasifiers 34,35,38,39 . Since the number of experiments replicated was relatively large, values for the mean absolute error were used for validation.…”

Section: Model Validationmentioning

confidence: 99%

An Energy and Exergy Analysis of Biomass Gasification Integrated with a Char-Catalytic Tar Reforming System

Buentello-Montoya

Zhang

2019

Energy Fuels

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Adequate tar removal is a recurrent challenge for biomass gasification. Materials such as char and activated char are promising catalysts for tar reforming because of their activity, inexpensiveness and constant production during gasification. Although the behaviour of char and activated char as catalyst has been previously studied, an evaluation of the thermodynamic efficiencies of the tar reforming process using char as a catalyst still lacking. This work analyses the performance of a two-stage system, where gasification is followed by tar reforming using char catalysts. For the study, a model based in a combination of equilibrium thermodynamics and chemical kinetics was developed. The first stage, where gasification occurs, was simulated with a thermodynamic equilibrium model. Gasification equilibrium models available in literature only predict the fractions of H 2 , CO, CO 2 and CH 4 ; the model developed for this work also predicts the formation of three model tar with different characteristics (benzene, toluene and naphthalene), providing information on the stability of formed tar. The second stage, simulated using kinetics from literature, consists on reforming the tar with catalysts made of residual char. The effects of the reactor temperature, equivalence ratio, and residence time were assessed via the gas quality, based on the gas lower heating value and tar concentration, and process efficiency, based on the energy and exergy efficiencies. Results showed that using char or activated char catalysts increases the heating value of the gas while reducing its tar concentration. Moreover, the process benefits thermodynamically (i.e. less exergy is destroyed) from low gasification temperatures and high reforming temperatures. Simulations indicate that a tarless gas with a lower heating value of more than 8 MJ/Nm 3 can be produced from gasification at 1023K with an equivalence ratio of 0.15 and subsequent reforming at 1123K with a residence time in the catalyst bed of 1 second.

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“…The concentration of CO2 increased at higher arc current because of stronger oxidative atmosphere due to enhanced dissociation of H2O at higher arc current. Importantly, gaseous products contained more than 86vol% of syngas, H2 and CO, which was much higher than 35vol% of the syngas concentration in the conventional gasification device by thermal decomposition (Tuomi et al, 2015). (1)…”

Section: Decomposition Of D-glucosementioning

confidence: 99%