Volatile matter release from coal at different heating rates –experimental study and kinetic modelling

Czajka, Krzysztof; Modliński, Norbert; Kisiela-Czajka, Anna M.; Naidoo, Reshendren; Peta, Sandile; Nyangwa, Bonny

doi:10.1016/j.jaap.2019.03.001

Cited by 22 publications

(7 citation statements)

References 26 publications

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“…Especially in the case of models 3 and 4, there is a correlation that minimization of the determination coefficient (R 2 ) and correlation (R) leads to high SNE values. This observation does not confirm the commonly used assumption that the models with R 2 > 0.7 describe the studied phenomena reliably [43,44]. It is therefore clear that fitting data by any of the non-linear equations based on the R or R 2 functions only, cannot be treated as evidence or prerequisite of the existence of a mechanism that determines the kinetics or dynamics of adsorption in a given system.…”

Section: Non-linear Regressionmentioning

confidence: 69%

Linear and Non-Linear Regression Analysis for the Adsorption Kinetics of SO2 in a Fixed Carbon Bed Reactor—A Case Study

Kisiela-Czajka

Dziejarski

2022

Energies

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Here, we determined the kinetic parameters of SO2 adsorption on unburned carbons from lignite fly ash and activated carbons based on hard coal dust. The model studies were performed using the linear and non-linear regression method for the following models: pseudo first and second order, intraparticle diffusion, and chemisorption on a heterogeneous surface. The quality of the fitting of a given model to empirical data was assessed based on: R2, R, Δq, SSE, ARE, χ2, HYBRID, MPSD, EABS, and SNE. It was clearly shown that the linear regression more accurately reflects the behaviour of the adsorption system, which is consistent with the first-order kinetic reaction—for activated carbons (SO2 + Ar) or chemisorption on a heterogeneous surface—for unburned carbons (SO2 + Ar and SO2 + Ar + H2O(g) + O2) and activated carbons (SO2 + Ar + H2O(g) + O2). Importantly, usually, each of the approaches (linear/non-linear) indicated a different mechanism of the studied phenomenon. A certain universality of the χ2 and HYBRID functions has been proved, the minimization of which repeatedly led to the lowest SNE values for the indicated models. Fitting data by any of the non-linear equations based on the R or R2 functions only cannot be treated as evidence/prerequisite of the existence of a given adsorption mechanism.

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Section: Non-linear Regressionmentioning

confidence: 69%

Linear and Non-Linear Regression Analysis for the Adsorption Kinetics of SO2 in a Fixed Carbon Bed Reactor—A Case Study

Kisiela-Czajka

Dziejarski

2022

Energies

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“…The C/N ratio is an important parameter in the study of thermochemical processes, which is useful in determining the most suitable energy conversion process. It was discovered that higher ratio values indicate a more suitable biomass for the gasification process [7,15]. However, lower values of this ratio in the biomasses confirm that the development of NOX would be minimised in the pyrolysis [28].…”

Section: Ultimate Analysismentioning

confidence: 99%

“…Diverse studies were carried out to observe the pyrolytic behaviour of biomasses, mainly using thermogravimetric (TG) analysis [5,14,15].TG analysis has been used as a proven technique to study the thermochemical phenomena of microalgae. The advantages of using a thermogravimetric analyser are its easy operation, minimal use of raw material, precise control and ability to record temperature and sample weight loss [16].…”

Section: Introductionmentioning

confidence: 99%

Volatile Compounds of Algal Biomass Pyrolysis

López-Aguilar

Quiroz-Cardoza

Pérez-Hernández

2022

JMSE

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The use and transformation of biomass into highly valuable products is a key element in circular economy models. The purpose of this research was to characterise the volatile compounds and the temperature at which they are emitted during the thermal decomposition by pyrolysis of algal biomass while looking at three different types: (A1) endemic microalgae consortium, (A2) photobioreactor microalgae consortium and (A3) Caribbean macroalgae consortium. Furthermore, the ultimate (CHON) and proximate (humidity, volatile solids and ashes) compositions of the algal biomass were determined. Some volatile species were identified as having potential industrial interest for use as precursors and intermediaries, such as commercially used aromatic compounds which if not suitably managed can be harmful to our health and the environment. It is concluded that the pyrolysis of algal biomass shows potential for the generation of valuable products. The information generated is useful, especially the temperature at which volatility occurs, in order to access the valuable compounds offered by the algal biomasses, and under the concept of biorefinery convert the issue of biomass disposal into a sustainable source of raw materials.

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“…Devolatilization Modeling Devolatilization is modeled with the competing two-step reaction mechanism (C2SM) [43] through the optimization procedure presented in [14]. The main benefit of this approach is that it accounts for the effect of operating conditions (fuel properties, heating rate) on the volatile matter release [46]. The optimization process yields kinetic parameters (the activation energy and pre-exponential factor) for C2SM, based on the results from the complex functional-group, depolymerization, vaporization, and cross-linking (FG-DVC) model.…”

Section: Devolatilizationmentioning

confidence: 99%

Entrained-Flow Coal Gasification Process Simulation with the Emphasis on Empirical Char Conversion Models Optimization Procedure

Mularski

Modliński

2021

Energies

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Computational fluid dynamics (CFD) modeling of an entrained-flow reactor is demonstrated and compared with experimental data. The study is focused on char conversion modeling and its impact on gasification simulation results. An innovative procedure of optimizing input data to empirical char conversion kinetic-diffusion model is investigated, based on the complex carbon burnout kinetic model for oxidation (CBK/E) and gasification (CBK/G). The kinetics of the CBK/G model is determined using the data from char gasification experiments in a drop tube reactor. CFD simulations are performed for the laboratory-scale entrained-flow reactor at Brigham Young University for the bituminous coal. A substantial impact of applied kinetic parameters on the in-reactor gas composition and char conversion factor was observed. The effect was most considerable for the reduction zone, where gasification reactions dominate, although a non-negligible impact could also be observed in the flame zone. Based on the quantitative assessment of the incorporated optimization procedure, its application allowed to obtain one of the lowest errors of CO, H2, CO2, and H2O axial distribution with respect to the experimental data. The maximum errors for these species were equal to 18.48, 7.95, 10.15, and 20.22%, respectively, whereas the average errors were equal to 4.82, 5.47, 4.72, and 9.58%, respectively.

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Volatile matter release from coal at different heating rates –experimental study and kinetic modelling

Cited by 22 publications

References 26 publications

Linear and Non-Linear Regression Analysis for the Adsorption Kinetics of SO2 in a Fixed Carbon Bed Reactor—A Case Study

Linear and Non-Linear Regression Analysis for the Adsorption Kinetics of SO2 in a Fixed Carbon Bed Reactor—A Case Study

Volatile Compounds of Algal Biomass Pyrolysis

Entrained-Flow Coal Gasification Process Simulation with the Emphasis on Empirical Char Conversion Models Optimization Procedure

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