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Biomass pyrolysis is a fundamental thermal conversion method that has both industrial and economic potential. A deep knowledge of the pyrolysis character can give dramatically rise to the general development of thermal conversion methods for the effective use of biomass fuel in the incoming future. In this work, kinetic parameters estimation methods and methodology for sewage sludge pyrolysis has been presented. Special emphasis was put into combined use of the latest isoconversional methodology and model-fitting kinetics. The kinetic parameters estimation was based on a series of experiments using thermogravimetric analysis carried out for heating rates 20, 30 and 40 K/min. Complimentary use of model-based and isoconversional approach along with statistical analysis of both methods results has been presented. The proposed methodology, based on Friedman isoconversional kinetic parameters, E α 31.4–244.9 kJ/mol and A α 1.17–14.4 log(1/s), as initial guess values for optimization resulted in 10 independent reactions kinetic model, evaluating sewage sludge pyrolysis with R2 > 0.999 with activation energies E ∈ < 30.34; 259.7> kJ/mol, pre-exponential factors A ∈<1.17; 22.49> log(1/s) and reaction orders n ∈<1.17; 3>. Isoconversional methodology resulted in excellent conversion rate and mass loss fit while the order-based kinetic model simultaneously gave insight into theoretical 10 elementary sludge decomposition rates. Image 1 • Combined isoconversional and model-based approach is used to simulate SS pyrolysis. • Friedman differential method provided initial values for kinetic computations. • 10 Independent Reaction model parameters were optimized using least-squares method. • The proposed methodology resulted in modeling of SS pyrolysis with R2 > 0.999. [ABSTRACT FROM AUTHOR]

Biomass pyrolysis is a fundamental thermal conversion method that has both industrial and economic potential. A deep knowledge of the pyrolysis character can give dramatically rise to the general development of thermal conversion methods for the effective use of biomass fuel in the incoming future. In this work, kinetic parameters estimation methods and methodology for sewage sludge pyrolysis has been presented. Special emphasis was put into combined use of the latest isoconversional methodology and model-fitting kinetics. The kinetic parameters estimation was based on a series of experiments using thermogravimetric analysis carried out for heating rates 20, 30 and 40 K/min. Complimentary use of model-based and isoconversional approach along with statistical analysis of both methods results has been presented. The proposed methodology, based on Friedman isoconversional kinetic parameters, E α 31.4–244.9 kJ/mol and A α 1.17–14.4 log(1/s), as initial guess values for optimization resulted in 10 independent reactions kinetic model, evaluating sewage sludge pyrolysis with R2 > 0.999 with activation energies E ∈ < 30.34; 259.7> kJ/mol, pre-exponential factors A ∈<1.17; 22.49> log(1/s) and reaction orders n ∈<1.17; 3>. Isoconversional methodology resulted in excellent conversion rate and mass loss fit while the order-based kinetic model simultaneously gave insight into theoretical 10 elementary sludge decomposition rates. Image 1 • Combined isoconversional and model-based approach is used to simulate SS pyrolysis. • Friedman differential method provided initial values for kinetic computations. • 10 Independent Reaction model parameters were optimized using least-squares method. • The proposed methodology resulted in modeling of SS pyrolysis with R2 > 0.999. [ABSTRACT FROM AUTHOR]

In light of the latest regulations in the energy sector, renewable energy sources are quickly becoming more important. Among renewable energy sources, the one that has the greatest potential for use in Poland is natural and waste biomass. Application of solar energy to biomass thermal conversion methods e.g., pyrolysis, affords the opportunity for additional solar energy storage as well as amplification of the pro-ecological effect of the entire conversion process. Precise control of waste biomass pyrolysis via an investigation into the process thermodynamics, kinetics, and heat transfer phenomena allows to direct the reaction for production of desirable products, ranting reduction in of disposal cost of biomass, even sewage sludge. The goal of this study was to develop new design of laboratory-scale solar pyrolytic reactors to investigate the solar pyrolysis of waste biomass. Within presented paper, pyrolysis fundamentals, including process thermodynamics and kinetic principles, were reviewed. In addition, recently-developed, and artificial-powered solar pyrolytic reactors were discussed with a brief comparison of popular light sources for solar pyrolysis studies. After numerous consultations with artificial light sources producers and researchers, own design of a solar pyrolytic reactor is presented, along with a project development, preliminary experiment results and basic methodology for future studies. • Solar pyrolysis is promising way of waste biomass conversion, free of greenhouse gases emissions. • Pyrolysis principles with emphasis on process thermodynamics and kinetics are presented. • Proper kinetic modelling of biomass pyrolysis is crucial to predict feedstock behaviour inside the reactor. • Solar pyrolysis studies performed on artificial light reactors in last 20 years are discussed. • Finally, solar pyrolysis reactor powered by 1.6 kW xenon-arc lamp, reaching 500 °C at 85.5% of lamp power is presented. [ABSTRACT FROM AUTHOR]

• High final solar pyrolysis temperatures favours gaseous hydrogen formation. • Actual heating rate profiles prove multi-step character of pyrolysis decomposition. • Obtained solid products HHV were 15.53, 12.28, 14.20 MJ/kg for WW, WS, and SS. • Model-free kinetic preditions showed correlation for dry pyrolysis gas formation. • The highest energy upgrade factors were obtained for WW with 12% upgrade value. A fixed-bed based solar pyrolysis of three waste biomass types: waste wood (WW), waste straw (WS), and sewage sludge (SS) was performed with emphasis on heating behaviour description, products yields, and quality. Laboratory solar pyrolysis reactor setup consists of a copper block indirectly heated by research-grade 1.6 kW xenon lamp radiation. Actual heating rates observed for 90, 95 and 100% xenon lamp power are 4.51, 5.32, and 5.49 K/min for WS; 5.10, 5.19, and 5.37 K/min for WW; and 3.95, 4.48, and 5.25 K/min for SS, respectively. Solar pyrolysis product yields (bio-oil, gas, char) were 51.68, 9.53, and 38.79 wt% for SS, 69.23, 9.18, and 21.59 wt% for WW, 62.30, 10.64, and 27.06 wt% for WS, denoted for the specific heating rates in ascending order. The highest quality bio-oil was obtained from WW pyrolysis with the lowest oxygen to carbon fraction and higher heating value (HHV) of 21.99 MJ/kg. Obtained chars, especially after solar pyrolysis of lignocellulosic biomass, presented HHV of 27.09 MJ/kg and 22.02 MJ/kg for WW and WS respectively, showed significant potential for renewable solid fuel. The increase of the lamp power, and long process time, caused degradation of porous structures within the biomass, where among the samples the highest specific surface area (BET) was denoted for WW samples at 5.2 K/min with 145.09 m2/g. Correlation between model-free kinetic predictions and gaseous species evolution was found, proving the value of apparent isoconversional activation energy profiles in describing actual solar pyrolysis gas compound formation at the laboratory scale. [ABSTRACT FROM AUTHOR]

The article presents a review of works on mathematical modelling of biomass pyrolysis process. Models types, number of dimensions, captured phenomena, type and dimensions of the reactors and biomass particles as well as models validation methods were analysed. Particular attention was paid to descriptions of chemical reactions, which are the essence of biomass thermal decomposition simulation. The article briefly describes the most important issues related to biomass pyrolysis and provides a review of commonly used methods of modelling this process with emphasis on solutions "ready to employ" in CFD modelling. A summary of other review papers on this topic is also provided. The problem of mathematical modelling in the context of "model - an engineering tool" was also discussed. Mathematical model for an engineering applications must be prepared with consideration of necessary consensus between the calculations accuracy, calculation time, preparation efforts and analysis requirements. Therefore, in pyrolysis modelling context, the inclusion of chemical reactions and changes of heat transport conditions were considered as priority, while taking into account moisture evaporation and bed shrinkage should be conditioned by their actual contribution in the calculations accuracy and by their influence on the calculations time. • A review of research on mathematical modelling of biomass pyrolysis is presented. • Captured phenomena, kinetic models, properties change, reactor types are summarized. • Compromise between model precision and calculations costs is discussed. [ABSTRACT FROM AUTHOR]