Evaluation on the non-isothermal combustion kinetics of lignite and sewage sludge through microwave pretreatment

In this paper, hydrochars and pyrochars were produced at 260 °C under different residence times (2 and 4 h) using anaerobic digested sewage sludge (SSL) as initial feedstock. The effect of reaction time on the fuel properties of hydrochars and pyrochars was evaluated. Moreover, the combustion kinetics of raw SSL and the derived pyrochars and hydrochars without coal blending were determined at two different air flows (20 and 90 mL/min) and compared. In the same conditions, the yield of hydrochar was significantly lower than that of pyrochar, confirming the different reaction pathways followed in each process. The results showed hydrochars have lower carbon recovery and energy yield than pyrochars, making the latter more suitable for energy purposes. The thermogravimetric combustion study showed that both thermochemical treatments increased the ignition temperature but decreased the burnout temperature, which results in higher stability during handling and storage. However, raw SSL is better for combustion than hydrochar according to the combustibility index. In addition, the kinetic study showed that the activation energy of the combustion of biochars, especially pyrochar, is lower than that of raw SSL, which is advantageous for their combustion.

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Combustion kinetics of lignite preheated under oxygen-enriched conditions

Energy & Environment ◽

10.1177/0958305x19882393 ◽

2019 ◽

Vol 31 (5) ◽

pp. 813-824

Author(s):

Özlem Uğuz ◽

Hanzade Haykiri-Açma ◽

Serdar Yaman

Keyword(s):

Horizontal Tube ◽

Reaction Model ◽

Treatment Temperature ◽

Combustion Kinetics ◽

Air Atmosphere ◽

Thermal Analyzer ◽

Isothermal Combustion ◽

Kinetics Of ◽

State Kinetic ◽

Horizontal Tube Furnace

This study bases on the testing of the solid-state kinetic models to determine the combustion kinetics of thermally pretreated Turkish lignite (Adiyaman–Golbasi) in O2-enriched environment. The lignite sample was first preheated in a horizontal tube furnace at temperatures of 200°C, 400°C and 600°C that correspond to torrefaction, partly devolatilization and partly ashing temperatures. Oxidative environments that have the O2 concentrations of 21, 30, 40 and 50 vol.%. were created during this treatment by changing the ratio of O2/N2 in the binary gas mixtures. The solid residues remaining after oxidation were then subjected to non-isothermal combustion conditions in a thermal analyzer up to 900°C under dry air atmosphere. The conversion degrees calculated from the thermogravimetric analysis were used to establish the kinetic parameters based on the Coats–Redfern method. It was concluded that the first-order reaction model fits well for both the combustion of volatiles and the burning of the char. It was also seen that the concentration of O2 in the pre-oxidation stage plays an important role as treatment temperature also increases. Moreover, it was also concluded that the activation energies for the char burning regions of the samples treated at 200°C and 400°C differ seriously.

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Isothermal combustion kinetics of synthetic refuse plastic fuel (RPF) blends by thermogravimetric analysis

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2016.04.151 ◽

2016 ◽

Vol 104 ◽

pp. 16-23 ◽

Cited By ~ 13

Author(s):

Yousuf Jamal ◽

Minho Kim ◽

Hung-suck Park

Keyword(s):

Thermogravimetric Analysis ◽

Combustion Kinetics ◽

Isothermal Combustion ◽

Kinetics Of

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Combustion kinetics of sewage sludge and combustible wastes

Journal of Material Cycles and Waste Management ◽

10.1007/s10163-009-0251-7 ◽

2009 ◽

Vol 11 (3) ◽

pp. 203-207 ◽

Cited By ~ 13

Author(s):

Ho-Soo Lee ◽

Sung-Keun Bae

Keyword(s):

Sewage Sludge ◽

Combustion Kinetics ◽

Combustible Wastes ◽

Kinetics Of

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Co-combustion kinetics of sewage sludge with coal and coal gangue under different atmospheres

Energy Conversion and Management ◽

10.1016/j.enconman.2010.02.030 ◽

2010 ◽

Vol 51 (10) ◽

pp. 1976-1980 ◽

Cited By ~ 85

Author(s):

Hanmin Xiao ◽

Xiaoqian Ma ◽

Kai Liu

Keyword(s):

Sewage Sludge ◽

Coal Gangue ◽

Combustion Kinetics ◽

Kinetics Of

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Combustion Kinetics of Metal Oxide and Halide Radicals.

10.21236/ada148521 ◽

1984 ◽

Author(s):

A. Fontijn

Keyword(s):

Metal Oxide ◽

Combustion Kinetics ◽

Kinetics Of

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Determining the mass-related reaction effectiveness factor of large, nonspherical fuel particles for bridging between intrinsic and apparent combustion kinetics

Journal of Thermal Analysis and Calorimetry ◽

10.1007/s10973-019-09085-9 ◽

2019 ◽

Vol 141 (2) ◽

pp. 797-806 ◽

Cited By ~ 2

Author(s):

Tibor Szűcs ◽

Pal Szentannai

Keyword(s):

Combustion Process ◽

Effectiveness Factor ◽

Cfd Modeling ◽

Combustion Kinetics ◽

Kinetic Measurements ◽

Environmental Requirements ◽

Fuel Particles ◽

Related Reaction ◽

Kinetics Of ◽

Internal Pore

AbstractThe utilization of challenging solid fuels in the energy industry is urged by environmental requirements. The combustion kinetics of these fuel particles differs markedly from that of pulverized coal, mainly because of their larger sizes, irregular (nonspherical) shapes, and versatile internal pore structures. Although the intrinsic reaction kinetic measurements on very small amounts of finely ground samples of these particles are mostly available, a bridge toward their apparent reaction modeling is not evident. In this study, a method is introduced to build this bridge, the goodness of which was proved on the example of an industrially relevant biofuel. To do this, the results of a macroscopic combustion measurement with real samples in a well-modelable environment have to be used, and for considering some not negligible effects, 3D CFD modeling of the experimental environment is also to be applied. The outcome is the mass-related reaction effectiveness factor as a function of the rate of conversion. This variable can be considered as the active fraction of the entire particle mass on its periphery, and it can be used as the crucial element in modeling the combustion process of the same particle under other circumstances by including the actual boundary conditions. Another advantage of this method is its covering inherently the entire combustion process (water and volatile release, and char combustion) and also its applicability for reactors utilizing bigger particles like fluidized bed combustors.

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