Comparison of pyrolysis test rigs for oxy-fuel conditions

Pielsticker, Stefan; Heuer, Sebastian; Senneca, Osvalda; Cerciello, Francesca; Salatino, Piero; Cortese, Luciano; Gövert, Benjamin Maximilian; Hatzfeld, O.; Schiemann, Martin; Scherer, Viktor; Kneer, Reinhold

doi:10.1016/j.fuproc.2016.10.010

Cited by 27 publications

(10 citation statements)

References 49 publications

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“…Xuan et al 156 used the sequential distributed activation energy method developed as part of the CPD model. The CPD model was used to estimate residence times and a heat source term by Pielsticker et al 157 Richards and Fletcher used CPD model calculations at heating rates from 5000 to 10 6 K/s to test several simpler model forms, including two-step models with and without distributed activation energies. Distributed activation energies were important to obtain good agreement over this range of heating rates.…”

Section: Use Of the Cpd Model To Determine Ratementioning

confidence: 99%

Review of 30 Years of Research Using the Chemical Percolation Devolatilization Model

Fletcher

2019

Energy Fuels

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The chemical percolation devolatilization (CPD) model for coal pyrolysis was first published in 1989, and a completed version that included the vapor–liquid equilibrium model and cross-linking model was published in 1992. The CPD model was one of three pyrolysis models developed using a lattice model to account for the chemical structure of the coal and was directly based on solid-state 13C nuclear magnetic resonance (NMR) measurements of the coal structure. A correlation of coal structure parameters measured by NMR spectroscopy was performed to permit use of the CPD model to determine pyrolysis rates and yields of tars and light gases for any coal type. A separate nitrogen release model was also developed on the basis of the chemical structure. In the past 30 years, the CPD model or the concepts in the CPD model have been used to describe pyrolysis in many situations for many fuels. The CPD model has been incorporated directly into simulations of large coal combustors as well as detailed simulations of single-pyrolyzing or burning coal particles, which was the original intent. Some investigators added a more rigorous treatment of light gas release. Other investigators have used the CPD model to determine rate coefficients for simpler models for a given range of heating conditions. In addition, the concepts in the CPD model have been used to develop models for other solid fuels, including biomass, black liquor, oil shale, rigid foams, propellants, heavy oil, asphalt, and scrap tires. The CPD model has also been extended to low heating rates for underground coal thermal treatment and hydropyrolysis. This paper is a review of the development, improvement, and uses of the CPD model, along with extended uses of the concepts in the CPD model.

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Section: Use Of the Cpd Model To Determine Ratementioning

confidence: 99%

Review of 30 Years of Research Using the Chemical Percolation Devolatilization Model

Fletcher

2019

Energy Fuels

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“…After heat treatment, the reactivity of the samples was compared by performing combustion or gasification experiments under the same well-defined conditions. Isothermal thermogravimetric analysis (TGA) at fixed temperature and concentration values (for example, 773 or 873 K in air or 1173 K in CO 2 ) has been employed for this scope; − however, also non-isothermal TGA tests have been used ,− ). Notably, the selection of conditions of the pre-pyrolysis step was arbitrary.…”

Section: Introductionmentioning

confidence: 99%

Extension of the Thermal Annealing Concepts Developed for Coal Combustion to Conversion of Lignocellulosic Biomass

et al. 2020

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During the lifetime of coal and biomass particles in a reactor, severe changes in the carbonaceous structure occur. In the early stages of heat treatment, transformations at both the structural and chemical level are dramatic and well-recognized in the literature under the name of pyrolysis. Further heat treatment, even in parallel with heterogeneous reaction, produces less evident changes but is still very impactful on the char reactivity in the late stages of burnoff, which are recognized in the literature under the name of thermal annealing. Thermal annealing of biomass has often been neglected and underestimated. In the present work, a large experimental campaign has been carried out to measure the effects of heat treatment on the reactivity of a lignocellulosic material, namely, walnut shells, and, for comparison, a bituminous coal. The campaign included experiments in a thermogravimetric analyzer, fixed bed reactor, drop tube reactor, heated strip reactor, and flat flame burner, spanning over a very wide range of temperatures (700–2300 K), heating rates (0.1–105 K/s), and residence times (0.02–20 000 s). Results provide a unique set of data useful for testing pyrolysis–annealing models on lignocellulosic materials. Thermal annealing is very relevant also for lignocellulosic biomass and reduces the reactivity of char up to 1 order of magnitude. However, the distinction between pyrolysis and thermal annealing is made complex by the presence of multiple components with different inertia to thermal treatment. The applicability of the concepts developed for thermal annealing of coal to lignocellulosic biomass is therefore open to discussion. It is observed that the boarder line between the stage of pyrolysis and the stage of thermal annealing can be reasonably set when approximately 70–80% of the (ASTM) volatile matter content has been released. The early stages of thermal annealing, involving aromatization and graphitization of the carbon structure, occur in parallel with pyrolysis tails.

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“…A joint research collaboration including researchers from the Aachen, Bochum, and Naples groups has recently undertaken an experimental campaign directed to investigate the course of pyrolysis of coal and biomass in CO 2 -rich atmospheres using different experimental setups. ,− The authors reported cases in which the composition of the pyrolysis atmosphere affected the quality of the resulting chars, suggesting the existence of mutual interactions between the purely pyrolytic process and the heterogeneous reaction with CO 2 , and cases in which this effect was negligible. , The experimental conditions examined in previous experimental campaigns by the groups in Naples, Bochum, and Aachen are summarized in Table .…”

Section: Introductionmentioning

confidence: 99%

Pyrolysis and Thermal Annealing of Coal and Biomass in CO₂-Rich Atmospheres

et al. 2018

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The high temperatures and heating rates typical of PF are known to induce thermal annealing of char and loss of its reactivity. Several authors investigated this effect for coals in inert atmospheres, while little is known about the effects of CO2-rich atmospheres, typical of oxy-combustion and gasification, on the course of thermal annealing. Thermal annealing of biomass has been scarcely investigated in the literature; however, available studies reported that also biomass can suffer from thermo-deactivation. The present study aims to provide further insight on thermal annealing of biomass in the context of gasification and oxy-combustion. A lignin-rich biomass (walnut shells) has been heat-treated in a heated strip reactor at temperatures of 1573–2073 K with a holding time of 3 s using atmospheres of either N2 or CO2. Similar experiments have been performed with a high volatile bituminous coal (Colombian coal) used as reference. The char samples have been analyzed by thermogravimetric analysis and Raman spectroscopy. Results have been further compared with those reported in previous studies where heat treatment of the same fuels were performed in fixed bed, fluidized bed, and drop tube reactors at lower temperature or shorter holding time. Two remarkable results have been obtained: (1) Loss of reactivity by thermal annealing and structural reorganization follow similar pathways for coal and biomass. (2) The effect of CO2 on pyrolysis and thermal annealing is non-monotonic along with heat treatment: in the early instances of heat treatment (T = 1573 K, t < 0.1 s), CO2 fosters pyrolysis and thermal annealing, increasing structural ordering. At longer holding times (T > 1573 K, t > 1 s), instead, CO2 somewhat hampers thermal annealing.

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Comparison of pyrolysis test rigs for oxy-fuel conditions

Cited by 27 publications

References 49 publications

Review of 30 Years of Research Using the Chemical Percolation Devolatilization Model

Review of 30 Years of Research Using the Chemical Percolation Devolatilization Model

Extension of the Thermal Annealing Concepts Developed for Coal Combustion to Conversion of Lignocellulosic Biomass

Pyrolysis and Thermal Annealing of Coal and Biomass in CO₂-Rich Atmospheres

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Comparison of pyrolysis test rigs for oxy-fuel conditions

Cited by 27 publications

References 49 publications

Review of 30 Years of Research Using the Chemical Percolation Devolatilization Model

Review of 30 Years of Research Using the Chemical Percolation Devolatilization Model

Extension of the Thermal Annealing Concepts Developed for Coal Combustion to Conversion of Lignocellulosic Biomass

Pyrolysis and Thermal Annealing of Coal and Biomass in CO2-Rich Atmospheres

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Pyrolysis and Thermal Annealing of Coal and Biomass in CO₂-Rich Atmospheres