Reaction kinetics and mass transfer studies of biomass char gasification with CO2

Mani, Thilakavathi; Mahinpey, Nader; Murugan, Pulikesi

doi:10.1016/j.ces.2010.09.033

Cited by 125 publications

(72 citation statements)

References 23 publications

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“…Some investigators [24] conducted a series of TG tests by varying the sample mass, gas flow rate, heating rate, particle size, and the height of crucible to minimize the inhibition of external and internal diffusions on the measurement in the TG and to characterize the intrinsic kinetics. Vincent et al [25] and Mani et al [26] believed that kinetics analysis could be considered intrinsic for char gasification of TG tests in the lower temperature range (750-900°C) and with fine particle size (\90 lm) without regard to other experimental parameters, while the case of char combustion might be quite different due to the relative lower activation energy of oxidation reaction. In addition, the role of diffusion was reported as a function of the conversion degree [27] and complementary analysis of the variation of the diffusional effects with conversion is necessary in particular for the kinetics analysis from TG experiments.…”

Section: Influence Of Diffusion Limitation On the Differences Of Charmentioning

confidence: 99%

Diffusional effects on differences of coal char reactivity between air and oxy-fuel combustion in thermogravimetric experiments

Wang

Han

et al. 2016

J Therm Anal Calorim

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Oxy-fuel combustion can realize large-scale CO 2 capture and low NO x emission from coal-fired power plants, while the evaluation of coal reactivity differences between air and oxy-fuel conditions is of importance for retrofitting existing conventional boilers to oxy-fuel ones. Here, two sets of specially designed experiments were contrastively conducted to assess the diffusional limitation effects on differences of coal char reactivity between air (O 2 /N 2 ) and oxy-fuel (O 2 /CO 2 ) combustion in nonisothermal thermogravimetric (TG) experiments, which were seldom investigated previously. Experimental results show that the TG/DTG curves of char combustion present distinct differences before and after reducing diffusional limitation. The differences of char combustion measured in non-isothermal TG experiments between O 2 /CO 2 and O 2 / N 2 conditions are shrinking with the reduction of diffusion resistance. Compared with conventional air combustion, change of combustion atmosphere in oxy-fuel condition mainly exhibits influence on diffusion process, while it has no observable effect on char-O 2 chemical reaction in TG experiments. Obviously different results between air and oxy-fuel combustion can be obtained when the diffusional limitation in TG tests is significant, while the change of combustion atmosphere has negligible influence on char reactivity under minimized inhibition of heat and mass transfer. Knowledge of the respective influence of intrinsic reaction and diffusion resistance on the measured TG experiments is of considerable significance for the exploration of reactivity and kinetics differences between air and oxy-fuel combustion.

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Section: Influence Of Diffusion Limitation On the Differences Of Charmentioning

confidence: 99%

Diffusional effects on differences of coal char reactivity between air and oxy-fuel combustion in thermogravimetric experiments

Wang

Han

et al. 2016

J Therm Anal Calorim

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“…21 In general, compared with coal or coke, biomass char has the following advantages: (1) higher CO 2 reactivity, (2) lower initial temperature to react with CO 2 , and (3) less ash content. [22][23][24] With these merits of biomass char and the knowledge obtained in processing the ore using gaseous reduction followed by melting separation, 25,26 the biomass char was considered applicable to process the ore for phosphorus removal in a method similar to the FASTMELT process; thus, a novel method was proposed by the present authors. In this method, biomass char is adopted as the reducing agent in direct reduction.…”

Section: Introductionmentioning

confidence: 99%

Production of Low-Phosphorus Molten Iron from High-Phosphorus Oolitic Hematite Using Biomass Char

Tang

Qin

2015

JOM

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In this study, an energy-saving and environmentally friendly method to produce low-phosphorus molten iron from high-phosphorus oolitic hematite was experimentally investigated and theoretically analyzed. The results indicate that biomass char is a suitable reducing agent for the proposed method. In the direct reduction stage, the ore-char briquette reached a metallization degree of 80-82% and a residual carbon content of 0.1-0.3 mass%. Under the optimized condition, phosphorus remained in the gangue as calcium phosphate. In the melting separation stage, phosphorus content ([%P]) in molten iron could be controlled by introducing a Na 2 CO 3 additive, and the phosphorus behavior could be predicted using ion molecular coexistence theory. Molten iron with [%P] less than 0.3 mass% was obtained from the metallic briquettes with the aforementioned quality by introducing 2-4% Na 2 CO 3 and the iron recovery rate was 75-78%.

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“…Thilakavathi et al (2010) calculated the reaction kinetic parameters of wheat straw char in a CO2 atmosphere using thermogravimetric analysis (TGA) and found that the char-CO2 reaction activity increased when the temperature rose from 750 °C to 900 °C. Butterman and Castaldi (2007) found that the biomass gasification reaction characteristics changed in a mixture of CO2 and steam prepared according to different proportions, indicating that the addition of a small quantity of CO2 allowed the most significant improvement in the steam gasification reactivity.…”

Section: Fig 1 Biomass Gasification Power Generation and Co2-reuse mentioning

confidence: 99%

Experimental Study on the Gasification Characteristics of Biomass with CO2/Air in an Entrained-flow Gasifier

Yu¹,

Chen²,

Xu³

et al. 2016

BioResources

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This study explored the gasification characteristics of pine sawdust and rice straw with CO2/air in a bench-scale entrained-flow gasifier. The effects of various gasification parameters, i.e., CO2/C, temperature, and biomass type, on the syngas composition, gasification index, and tar yield were investigated. When compared to air gasification, the CO2/air agent for gasification improved the yield of CO, and it decreased the tar yield and the yield of CO2 produced from biomass. The cold gas efficiency (CGE) of pine sawdust reached 87.06% at the CO2/C equivalence ratio of 0.25, whereas that of rice straw reached 73.35% at the CO2/C equivalence ratio of 0.50. When compared with air gasification, the CO2/air gasification increased the CGE of pine sawdust and rice straw by 4.20% and 9.17%, respectively. However, excessive CO2 was unfavorable to the gasification process. As the temperature increased, the yields of CO and H2 increased, and the tar yield decreased, thus improving the syngas quality. This study indicated that the addition of the proper level of CO2 for gasification improved the overall gasification efficiency. Moreover, the improvement for rice straw (herbaceous plant) was more noteworthy than for pine sawdust (woody plant).

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Reaction kinetics and mass transfer studies of biomass char gasification with CO2

Cited by 125 publications

References 23 publications

Diffusional effects on differences of coal char reactivity between air and oxy-fuel combustion in thermogravimetric experiments

Diffusional effects on differences of coal char reactivity between air and oxy-fuel combustion in thermogravimetric experiments

Production of Low-Phosphorus Molten Iron from High-Phosphorus Oolitic Hematite Using Biomass Char

Experimental Study on the Gasification Characteristics of Biomass with CO2/Air in an Entrained-flow Gasifier

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