Pellet Breakup Due to Pressure Generated during Wood Pyrolysis

Hastaog̃lu, Mehmet A.; Kahraman, Ramazan; Syed, Muhammad Q.

doi:10.1021/ie000037s

Cited by 20 publications

(8 citation statements)

References 17 publications

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“…However, when compared with the massive investigations related to physical models, studies on the effects of different devolatilization schemes for biomass fast pyrolysis at the reactor scale are very few. A literature review has shown that the effects of devolatilization schemes on the simulation results were investigated only at the particle scale . The details of biomass fast pyrolysis at the reactor scale are inherently more complicated than those encountered at the particle scale.…”

Section: Introductionmentioning

confidence: 99%

Assessment of devolatilization schemes in predicting product yields of biomass fast pyrolysis

Xiong

Aramideh

Kong

2014

Env Prog and Sustain Energy

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Three devolatilization schemes to simulate biomass fast pyrolysis were tested and validated in this study. Fast pyrolysis is an attractive process in converting lignocellulosic biomass to valued products. Accurate numerical models can help understand the conversion process and be used for reactor design and optimization. This study used a numerical model that considered the multiphase hydrodynamics and chemical reactions of biomass fast pyrolysis. The gas and solid phases were simulated by using a multifluid model that considered multiple species in each phase. Three devolatilization schemes for biomass fast pyrolysis were incorporated into the model to simulate the tempo-spatial evolutions of all phases and species. The predicted product yields were compared and validated using experimental data. It was found that the best predictions were given by a scheme that used three components to represent biomass and also considered organic liquid cracking into gas. Under the reactor conditions studied, all three devolatilization schemes predicted relatively fast decomposition of biomass and the reactor hydrodynamics was not significantly affected by the specifics of the devolatilization schemes. Overall, an accurate devolatilization scheme to simulate the chemical changes of biomass particles is essential to predicting the product yield of biomass fast pyrolysis at the reactor scale.

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Section: Introductionmentioning

confidence: 99%

Assessment of devolatilization schemes in predicting product yields of biomass fast pyrolysis

Xiong

Aramideh

Kong

2014

Env Prog and Sustain Energy

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“…The governing equations for heat and mass transfer with the boundary and initial conditions and auxiliary equations for some selected properties are given below with with The grain size and porosity are continuously updated using equations presented previously . Heat- and mass-transfer coefficients are obtained through established correlations.…”

Section: Mathematical Equationsmentioning

confidence: 99%

“…Conservation equations for mass and heat transfer The grain size and porosity are continuously updated using equations presented previously. 21 Heat-and masstransfer coefficients are obtained through established correlations.…”

Section: Mathematical Equationsmentioning

confidence: 99%

Treatment of Wood Pyrolysis Data via a Multiple Gas−Solid Reaction Model

and

Al-Khalid

2001

Ind. Eng. Chem. Res.

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Wood pyrolysis consisting of water evaporation, consecutive, and parallel reactions was modeled through a multiple gas−solid reaction scheme. Effective kinetic parameters were determined through the model and compared to the results of a conventional differential method where the results differed substantially. The behavior of global wood conversion is compared to the experimental results. System parameters and variables, transport coefficients, and thermophysical properties are determined transiently. The millimeter sized pellets were found to have substantial gradients within. The heating rate of thermogravimetric analysis equipment is also considered in the model. The rate expressions were developed based on molar solid concentrations in the wood fibers. For the simulation grain (pore or fiber), pellet and reactor spaces of different magnitudes were considered. The effective quantities were ΔE 1 = 255.7 kJ/mol, k 10 = 8.5 × 1018 s-1, ΔE 3 = 140.7 kJ/mol, and k 30 = 4 × 106 s-1.

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“…Pressure build-up inside the particle has a significant effect on the product distribution as the trapped gases can undergo secondary reactions . Also, the convective flow of gas out of the particle affects the interaction of the particles with the environment, while high pressure inside the particle can cause mechanical degradation up to the point of cracking of the particle. , …”

Section: Introductionmentioning

confidence: 99%

“…3 Also, the convective flow of gas out of the particle affects the interaction of the particles with the environment, 4 while high pressure inside the particle can cause mechanical degradation up to the point of cracking of the particle. 3,5 Modeling of biomass pyrolysis has received considerable attention in the literature. 6−9 Typically, the models are based on conservation equations for mass and energy, commonly referred to as the balance equations.…”

Section: ■ Introductionmentioning

confidence: 99%

1D Finite Volume Scheme for Simulating Gas–Solid Reactions in Porous Spherical Particles with Application to Biomass Pyrolysis

Sadegh-Vaziri

Winberg-Wang

Bäbler

2021

Ind. Eng. Chem. Res.

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Models for gas−solid reactions in porous particles typically consist of a set of mass and energy balances in the form of conservation equations. For spherical or close to spherical particles, these equations are formulated in 1D spherical coordinates. In the case where accumulation of gas inside the particle is significant, the balance equations contain convective terms. The present work presents a simple numerical scheme based on flux limited finite volume methods for discretizing conservation equations for convective and diffusive transport of mass and energy in radial direction in a porous sphere. The velocity is governed by Darcy's law coupled to an equation of state. The proposed scheme is applied to a series of test problems that admit full or partial analytical solutions. For the cases where only partial analytical solutions are available, a Comsol model is adopted for comparison. It is found that the scheme is able to resolve step gradients without generating oscillations and that it properly handles changes in the sign of the convective velocity. Applying the scheme for solving a common model for biomass pyrolysis reveals the importance of convective gas transport in the pyrolysis of thermally thick biomass particles.

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Pellet Breakup Due to Pressure Generated during Wood Pyrolysis

Cited by 20 publications

References 17 publications

Assessment of devolatilization schemes in predicting product yields of biomass fast pyrolysis

Assessment of devolatilization schemes in predicting product yields of biomass fast pyrolysis

Treatment of Wood Pyrolysis Data via a Multiple Gas−Solid Reaction Model

1D Finite Volume Scheme for Simulating Gas–Solid Reactions in Porous Spherical Particles with Application to Biomass Pyrolysis

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