A reactivity study of chars obtained at different temperatures in relation to their petrographic characteristics

Alonso, M.; Borrego, Ángeles G.; Alvarez, Diego; Menéndez, Rosa

doi:10.1016/s0378-3820(00)00146-6

Cited by 43 publications

(43 citation statements)

References 28 publications

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“…(1) proposed by Kissinger [10]. (1) This method uses the fact that the temperature of the maximum reactivity (T m ) increases with increasing heating rate (β), so the method can be available to calculate activation energy (E a ) in a non-isothermal experiment. From this equation, activation energy could be calculated by determination of the slope of the plot for ln(β/T m 2 ) versus 1/T m .…”

Section: Methodsmentioning

confidence: 99%

“…The combustion behavior of coals depends on the characteristics of the coals such as volatile and ash content, surface area and active sites, minerals in ash and rank of coals as well as on the combustion conditions such as temperature, heating rate, oxygen concentration and so on [1,2]. It is generally accepted that the combustion of coal particles has a series of reactions that involve a pyrolysis stage in an oxygen lean atmosphere and a heterogeneous reaction stage of oxygen with the carbon-rich solid residue named char [3].…”

Section: Introductionmentioning

confidence: 99%

“…Of these reactivity studies, the determination of reactivity of char combustion by TGA (thermogravimetric analysis), which has proved to be a valuable tool in the assessment of the combustion reactivity of coals, is usually achieved by using char particles formed at a high temperate under inert atmosphere (N 2 ) [6][7][8]. However, the combustion of the char particles is influenced by petrographic characteristics of coals affected by release and combustion of volatile matter with oxygen in coal particles [1,2,9].…”

Section: Introductionmentioning

confidence: 99%

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Reactivity study of combustion for coals and their chars in relation to volatile content

Lee

Kim

2009

Korean J. Chem. Eng.

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To determine the effect of volatile matter on combustion reactivity, the pyrolysis and combustion behavior of a set of four (R, C, M and K coals) coals and their chars has been investigated in a TGA (SDT Q600). The maximum reaction temperatures and maximum reaction rates of the coals and their chars with different heating rates (5-20 o C/ min) were analyzed and compared as well as their weight loss rates. The volatile matter had influence on decreasing the maximum reactivity temperature of low and medium rank coals (R, C and M coals), which have relatively high volatiles (9.5-43.0%), but for high rank coal (K coal) the maximum reactivity temperature was affected by reaction surface area rather than by its volatiles (3.9%). When the maximum reaction rates of a set of four coals were compared with those of their chars, the slopes of the maximum reaction rates for the medium rank coals (C and M coals) changed largely rather than those for the high and low rank coals (R and K coals) with increasing heating rates. This means that the fluidity of C and M coals was larger than that of their chars during combustion reaction. Consequently, for C and M coals, the activation energies are lower (24.5-28.1 kcal/mol) than their chars (29.3-35.9 kcal/mol), while the activation energies of R and K coals are higher (25.0-29.4 kcal/mol) than those of their chars (24.1-28.9 kcal/mol).

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reactivity study of combustion for coals and their chars in relation to volatile content

Lee

Kim

2009

Korean J. Chem. Eng.

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“…Many researches have been conducted to analyze the reactivity of char by using the TGA method and many criteria had been introduced [1][2][3][4][5][6][7][8][9]. Some of them are summarized in Table 1.…”

Section: Introductionmentioning

confidence: 99%

“…In non-isothermal TGA experiment, the reactivity is usually checked by using the weight loss rate (usually refers to the maximum weight loss rate or the weight loss rate where the carbon conversion rate reaches 50%) [4,10,11]. The faster the combustion, the higher the weight loss rate, and the better the reactivity of the sample.…”

Section: Introductionmentioning

confidence: 99%

Parameter for judging reactivity of coal and coke

Luo

Cen

2008

Front. Energy Power Eng. China

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To eliminate the judgment error of char reactivity arising from different carbon content of samples, a new parameter called specific maximum weight loss rate was introduced. It is defined as the quotient of the maximum weight loss rate in non-isothermal thermogravimetric analysis (TGA) experiment to the carbon content of the corresponding sample. The reactivity of different kinds of coal, the reactivity of the same coal type with different lithotype, and the reactivity of the char with different carbon conversion rates were checked by using the specific maximum weight loss rate, and the results were analyzed and compared with those obtained by using other criteria. The results show that the specific maximum weight loss rate can be used as a commonality parameter to evaluate and distinguish the reactivity of different coal and char. The heating rate selected in TGA experiment has no effect on the judgment. The experiment was conducted on a Mettler TOLEDO TGA/ SDTA 851 Thermo-balance analyzer. The reactivity of different coal; including Long-Yan anthracite (LY), Yang-Quan anthracite (YQ), Shao-Yang anthracite (SHY), Yi-Ma bituminous (YM); and the reactivity of the coal with different lithotypes, including the clarain coal of Long-Yan anthracite (LY-Clarain), the culm coal of Long-Yan anthracite (LY-Culm), and the dull coal of Long-Yan anthracite (LY-Durian); were measured in the experiment.The non-isothermal TGA method was applied in experiment. The sample (with a particle diameter of less than 200 mesh and a weight of 10 ¡ 0.5 mg) was heated from environmental temperature to 1000uC in air at a flow rate of 80 mL/min. Three different heating rates (10 K/min, 25 K/min and 40 K/min) were selected respectively.

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Influence of pyrolysis condition and coal type on char gasification reactivity

Wang

Chen

Yang

et al. 2011

Asia-Pacific J Chem Eng

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The CO 2 gasification property of char particles was investigated with pressurized and ambient thermal analyzer with four typical Chinese industrial coals as samples. The influence of pyrolysis pressure and final temperature was analyzed and a new index (specific maximum gasification rate) of char CO 2 gasification reactivity was approached. The process of char gasification can be divided into two steps: the thermal cracking and CO 2 shifting of volatile hydrocarbon residues and the CO 2 shifting of carbon matrix. Higher pressure did not show positive effect on char gasification enhancing as pyrolysis pressure lower than 1.5 MPa, whereas it was accelerated with pressure increasing further as more volatile hydrocarbon left in char particles. Temperature showed variant influence on char gasification with different pyrolysis pressures. There exist some interaction between pyrolysis temperature and pressure. Furthermore, coal type played vital role on char gasification behavior and the specific maximum gasification rate showed great consistency with char gasification behavior.

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A reactivity study of chars obtained at different temperatures in relation to their petrographic characteristics

Cited by 43 publications

References 28 publications

Reactivity study of combustion for coals and their chars in relation to volatile content

Reactivity study of combustion for coals and their chars in relation to volatile content

Parameter for judging reactivity of coal and coke

Influence of pyrolysis condition and coal type on char gasification reactivity

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