In this work, an Euler–Euler multiphase CFD model is proposed for continuous fast pyrolysis of biomass in a fluidized-bed reactor. In the model, a lumped, multi-component, multi-stage kinetic model is applied to describe the pyrolysis of a biomass particle. Variable particle porosity is used to account for the evolution of the particle's physical properties. Biomass is modeled as a composite of three reference components: cellulose, hemicellulose, and lignin. Pyrolysis products are categorized into three groups: gas, tar vapor (bio-oil), and solid char. The particle kinetic processes and their interactions with the reactive gas phase are modeled with a multi-fluid description derived from the kinetic theory of granular flows. A time-splitting approach is applied to decouple the convection and reaction calculations using a synchronized time step. The CFD model is employed to study the fast pyrolysis of both cellulose and bagasse in a lab-scale fluidized-bed reactor. The dynamics, particle heating, reaction of the biomass phase, char formation, elutriation, and spatial distribution of tar and gas inside the reactor are investigated. The yields of tar, gas, and char are also discussed.

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A CFD model for biomass fast pyrolysis in fluidized-bed reactors

https://research.chalmers.se/publication/510826/file/510826_Fulltext.pdf

11,000 h of chemical-looping combustion operation—Where are we and where do we want to go?

Because the CO2 capture is inherent in chemical looping combustion (CLC), thus ideally avoiding costly gas separation, this process has potential for uniquely low costs of CO2 capture The review reports on operational experiences with different oxygen carriers in CLC pilot operation Further, the application to solid fuels is discussed in terms of technology challenges, routes for upscaling to commercial size, downstream gas treatment, options for achieving adequate circulation, and the use of biofuels in CLC to reach negative emissions It is concluded that the necessary elements for a scale-up are at hand Oxygen carrier materials of low cost have been tested in extended operation and found to have reasonable performance with respect to reactivity and lifetime Designs for large-scale units have been performed, indicating that the process is technically realistic and should have a low cost of CO2 capture A scale-up strategy to minimize risk and costs has been suggested

Chemical Looping Combustion: Status and Development Challenges

A modified Levenberg–Marquardt algorithm for simultaneous estimation of multi-parameters of boundary heat flux by solving transient nonlinear inverse heat conduction problems

The calcium looping (CaL) process is a promising CO2 capture technology, which uses CaO-based sorbents by employing a reversible reaction between CaO and CO2, generally named as carbonation and cal...

Review on the development of sorbents for calcium looping

An inverse method to reconstruct the heat flux produced by bone grinding tools

Auto-thermal operation and optimization of coal-fueled separated gasification chemical looping combustion in a pilot-scale unit

Real-time temperature field reconstruction of boiler drum based on fuzzy adaptive Kalman filter and order reduction

This study presents a comprehensive three-dimensional full loop simulation on a novel in situ gasification chemical looping combustion (iG-CLC) system. This iG-CLC model mainly consists of a high-flux circulating fluidized bed fuel reactor, a counter-flow moving bed air reactor, an inertial separator, a J-valve, and a downcomer. The Eulerian–Eulerian two-fluid model incorporated with the standard k–e turbulence model for the gas phase and the kinetic theory of granular flow for the solid phase was applied to model the gas–solid flow dynamics characteristics in the whole system. The quasi-stable solid circulation in the whole system could be realized after about 20 s of the computational time with the Gidaspow drag model and the specularity coefficient of 0.5, in which the fuel reactor and air reactor achieved intense turbulence flow and steady near plug flow, respectively. However, when the AR inlet gas flow exceeded a critical value, the stable flow state in the AR would be destroyed due to the appearanc...

/pdf/three-dimensional-full-loop-modeling-and-optimization-of-an-1s9frlcwhv.pdf

Xudong Wang

Papers

An inverse method to reconstruct the heat flux produced by bone grinding tools

Auto-thermal operation and optimization of coal-fueled separated gasification chemical looping combustion in a pilot-scale unit

Real-time temperature field reconstruction of boiler drum based on fuzzy adaptive Kalman filter and order reduction

Three Dimensional Full Loop Modeling and Optimization of an in Situ Gasification Chemical Looping Combustion System

Coal-fueled separated gasification chemical looping combustion under auto-thermal condition in a two-stage reactor system