Kinetic modelling of char gasification by accounting for the evolution of the reactive surface area

Zoulalian, André; Bounaceur, Roda; Dufour, Anthony

doi:10.1016/j.ces.2015.07.035

Cited by 27 publications

(16 citation statements)

References 62 publications

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“…Thermal analysis is widely used for research on combustibility and oxidation behaviours of coal char . Kelebopile et al studied the reactivity of high carbon fly ash obtained from a CFB gasification system using thermogravimetric analysis (TGA).…”

Section: Introductionmentioning

confidence: 99%

“…Thermal analysis is widely used for research on combustibility and oxidation behaviours of coal char. [14][15][16][17][18][19] Kelebopile et al [14] studied the reactivity of high carbon fly ash obtained from a CFB gasification system using thermogravimetric analysis (TGA). The results showed that compared with fast pyrolysis char, combustion reactivity of gasification fly ash from CFB was poor.…”

Section: Introductionmentioning

confidence: 99%

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Combustion characteristics of ultrafine gasified semi‐char in circulating fluidized bed

Ren

Shu

2016

Can J Chem Eng

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Coal fluidized bed gasification generates large amounts of semi‐char, which has a high carbon content. Effectively re‐burning semi‐char has become a promising way to improve overall conversion efficiency of coal gasification and use the residue carbon in the semi‐char. However, due to the ultrafine particle size (mean particle size ≈ tens of microns), nearly zero volatile content, and the graphitization structure of the semi‐char, the fluidization and combustion organization of semi‐char in a circulating fluidized bed (CFB) is difficult, leading to poor self‐sustained combustion stability and low combustion efficiency. The physicochemical properties of the semi‐char from an industrial CFB gasifier were studied. The combustion characteristics and activation energy of the semi‐char were tested using thermogravimetric analysis. The occurrence of sulphur and nitrogen in the semi‐char and fly ash after combustion were characterized with X‐ray photoelectron spectroscopy (XPS). A re‐burning experiment was carried out in a 5 t/day CFB pilot facility. The key is to build a balance between sufficient residence time to burnout and a proper fluidization velocity for bed material cycle. The effects of residence time, preheating temperature, and the ratio of preheating air to fuel on the combustion efficiency and pollutant emission was studied. The balance between the preheating time and residence time in the furnace was discussed. Results show that it can reach stable combustion in a specially designed CFB furnace without auxiliary fuel and the combustion efficiency can be higher than 98 %.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Combustion characteristics of ultrafine gasified semi‐char in circulating fluidized bed

Ren

Shu

2016

Can J Chem Eng

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“…It is connected with both a bigger intensiveness on the whole and with influence increase of porous structure of fuel particles on process kinetics. The received data are coordinated with values presented in literature for analogous coals [4][5][6].…”

Section: Parameters Of Pyrolysismentioning

confidence: 99%

“…Pyrolysis is thermochemical process of volatiles deletion from coal and partial oxidation which strongly influences final value of coal transformation degree and mass decrease rate [4]. A lot of chemical and physical processes occur at this stage: drying, volatiles output, cracking and burning.…”

Section: Introductionmentioning

confidence: 99%

Dependence of Pyrolysis Rate of Coal on Temperature

Slyusarskiy

Bejsekov

Marysheva

et al. 2015

MATEC Web of Conferences

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Abstract. Pyrolysis process of coal has been researched to define kinetic constants which can be used for design and optimization of different processes of fuel transformation. The article considers anthracite powders and bituminous coal of Krasnogorsky mine with the use of nonisothermal thermogravimetric analysis with mass spectrometry. Spectroscanning microscopy and laser diffraction for definition of sizes and forms of particles distribution has been done. Other parameters -carbon content, ash and volatiles, density and moisture have been defined by standard methods. Energy of activation and pre-exponent with the use of models of Freedman, Starink and distributed activation energy model (DAEM), and also relative deviation of design data from experimental ones have been designed. The results of the analysis have shown the important influence of volatiles content and coal transformation degree on maximum reaction rate. Energy activation values received with the help of DAEM model are higher than with Freedman and Starink models. Process of pyrolysis of bituminous coal has a big rate in comparison with anthracite, and is better described by the abovementioned models.

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“…The effect of coal bed thickness was studied and compared between steam and CO 2 gasification. Zoulalian et al (2015) proposed model that presents a simple method to handle the evolution of the total surface area and of the reactive surface area. The model was applied to coal and wood char for O 2 , CO 2 and H 2 O gasification experiments (taken from the literature).…”

Section: Introductionmentioning

confidence: 99%

Analyzing chemical kinetics of coal gasification in mini gasifier reactor

Efendi

Sofaety

2017

IMJ

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Coal gasification is a chemical reaction that has a purpose to change the original solid coal into gaseous compounds. Converting the coal into gaseous compounds will make the combustion process easier and results in increasing combustion efficiency. The sulfur and nitrogen are also easier to be separated in order to obtain cleaner flue gas. This paper presents kinetic analysis of coal gasification reactions in mini gasifier (or known as GasMin in Bahasa) reactor. The results show that the increase of the air-coal ratio (ACR) affected the maximum temperature of the reactor, which means that an increase of the intake air flow rate will increase the amount of oxygen for combustion reaction. Meanwhile, the increase of the team coal ratio (SCR) will increase flow rate of the mixture of air-steam feed. As a result, the ability of coal gasification has also increased. This will increase gasification efficiency around 3-5% which then will also increase the gas yield. The maximum value of SCR was 0.06, further than that of the yield gas and the qvalue will slightly decrease. The simulation result showed that the producer gas was dominated by CO with 26.72% mole fraction; H2 with 14.06% mole fraction, and N2 with 47.88% mole fraction. Meanwhile CO2, CH4 and O2 mole fraction were 5%, 0.24%, and 1.20% respectively.Keywords: coal, gasification, mini gasifier, kinetic reactions. ABSTRAK Gasifikasi batubara adalah reaksi kimia yang bertujuan untuk mengubah batubara padat menjadi senyawa gas. Dengan mengubah batubara menjadi senyawa gas, proses pembakaran menjadi lebih mudah sehingga efisiensi pembakaran meningkat. Sulfur dan nitrogen juga lebih mudah dipisahkan sehingga mendapatkan produk pembakaran yang bersih. Makalah ini menyajikan analisis kinetika proses gasifikasi batubara pada reaktor gasifikasi mini (GasMin

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Kinetic modelling of char gasification by accounting for the evolution of the reactive surface area

Cited by 27 publications

References 62 publications

Combustion characteristics of ultrafine gasified semi‐char in circulating fluidized bed

Combustion characteristics of ultrafine gasified semi‐char in circulating fluidized bed

Dependence of Pyrolysis Rate of Coal on Temperature

Analyzing chemical kinetics of coal gasification in mini gasifier reactor

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