A 1-dimensional model for an atmospheric circulating fluidized bed biomass gasifier (CFBBG) under stationary state is presented in this paper. The model is based on the kinetic equations for the reaction network solved together with mass and heat balances and with several hydrodynamic considerations.

A cold flow model was built and operated in order to study the fluid dynamics of a 120-kW chemical looping pilot rig for gaseous fuels. The system consists of two interconnected circulating fluidized bed reactors with globally circulating bed material (dual circulating fluidized bed – DCFB).

A Comprehensive Pressure Balance Model of Circulating Fluidized Beds. Hongwei Lei M. Horio. Engineering. 1998; Based on the concepts of clustering suspension and core-annulus flow in the riser, a pressure balance model for the entire loop of a circulating fluidized bed system was developed, ...

The formation of clusters in liquid–solid circulating fluidized beds effects on momentum transfer between phases. In this article, a cluster structure-dependent drag model is proposed to take the effect of clusters on momentum transfer between dispersed phase and clusters into account by means of an Eulerian–Eulerian two-fluid model.

Modeling of next-generation CO2 capture technology, namely, chemical looping combustion (CLC), in bubbling and circulating fluidized bed reactors is briefly reviewed, and a summary of published mathematical …

This contribution underscores the importance of selecting an appropriate interphase momentum transfer model for accurately predicting the distribution of the solid phase in a full-scale circulating fluidized bed (CFB) riser equipped with a smooth C-type exit. It also explores other critical factors such as domain configuration, grid size, the …

This paper presents a three-dimensional, steady state combustion model for a circulating fluidized bed (CFB) furnace and several calculation cases which have been used for the validation of the model. The model includes essential submodels to describe the complex combustion process in a circulating fluidized bed boiler. These include …

Abstract An improved version of a combustion-desulfurization model for fluidized bed combustors burning high ash and sulfur content low quality lignite in its own ash with the addition of limestone…

The first CFD model for a circulating fluidized bed, with a riser and down comer, was published by Gidaspow et al. . Results for the kinetic theory model are described in [ 15 ]. The non-CFD design, including rates of reaction, is described in [ 16 ].

Introduction. Gas–solid fluidization technology has expanded from low-velocity conventional fluidization to high-velocity circulating fluidization during the past century (Bi & Grace, 1995).In addition to the conventional fluidized beds such as bubbling or turbulent bed, circulating fluidized bed (CFB) system was widely utilized in chemical industries …

In the analysis of the operating characteristics of the supercritical CFB unit, Gao et al. [7] used the lumped parameter model to analyze the dynamic characteristics of subcritical coal-fired circulating fluidized bed units and established a CCS mechanism control model that balances model complexity and prediction accuracy, suitable for ...

A mathematical model has been developed which successfully describes the dynamics around a circulating fluidized bed loop. The dilute phase region of the fast bed, including the acceleration zone, can be correlated with pneumatic transport equations developed by the author earlier (Yang 1977).

1. Introduction. A loop seal, as one of the most widely used non-mechanical valves in circulating fluidized beds (CFB) or other related processes, serves as a recycle device allowing the transfer of the solids from the high-pressure standpipe to the low-pressure riser, but preventing the inverse flow of the gas from the riser bottom to the …

A cold model study was carried out of an internally circulating fluidized bed membrane reactor for hydrogen production by steam reforming. This configuration facilitates a novel process in which air is introduced for autothermal operation, while avoiding diluting the hydrogen in the gas stream by nitrogen.

An integrated model, namely the two-equation turbulent model, is introduced to simulate mass transfer in a liquid–solid circulating fluidized bed (LSCFB) riser. Protein desorption is simulated and the proposed model is validated. The protein concentration profiles simulated with this model agree well with published experimental results.

A comprehensive model is developed for the combustion of coal in a circulating fluidized bed combustor (CFBC). The proposed model integrates hydrodynamic parameters, reaction model and kinetic subroutines necessary to simulate coal combustion in a CFBC. ... YXcao,a- I 2 (16) Fuel 1998 Volume 77 Number 4 331 …

This review aims to overview the process modeling of CLC in fluidized bed reactors, focusing on the macroscopic modeling approach and the use of semiempirical correlations to describe the relevant bubbling and circulating fluidized bed phenomena.

A computational particle fluid dynamics model of a pilot scale circulating fluidized bed (CFB) was used to numerically simulate its gas–solid flow characteristics. The bed pressure drop characteristics of the CFB were obtained for different bed material heights. The accuracy of the model was confirmed by comparing the simulation results …

The simulations are based on the coupled CFD/DEM model and carried out by the DEMEST code. Here, two cases, namely a quasi-2D fluidized bed and a 3D circulating fluidized bed with a particle separator, are calculated. The considered forces on the particles are gravitational, buoyancy, drag, pressure, Saffman, Magnus, and …

A kinetic theory based hydrodynamic model with experimentally determined sorption rates for reaction of CO2 with K2CO3 solid sorbent is used to design a compact circulating fluidized bed sorption ...

Circulating fluidized bed reactors are widely used for the combustion of coal in power stations as well as for the cracking of heavy oil in the petroleum industry. A two-dimensional reactor model for circulating fluidized beds (CFB) was studied based on the assumption that at every location within the riser, a descending dense phase and a rising lean phase …

Prediction and minimization of NO x emission in a circulating fluidized bed combustor: Improvement of bed quality by optimizing cyclone performance and coal particle size. Author links open ... (PFR) with solid back-mixing. The details of this CFB mathematical model, including sub-model description, cell division method, numerical …

A steady state model of a coal-fired circulating fluidized-bed boiler, based on hydrodynamics, heat transfer and combustion, is presented.This model predicts the flue gas temperature, the chemical gas species (O 2, H 2 O, CO, CO 2 and SO 2) and char concentration distributions in both the axial and radial locations along the furnace …

The following examples, based on reactor experiments reported by felder et al. (1996), show how to use this model for the various flow regimes (see Fig. 9).But first, Table 1 outlines the regimes studied. From felder et al. (1996) we have d p =50×10 −6 m, ρ s =1420 kg/m 3, 20°C, 100 kPa, u mf =1.9×10 −3 m 3 gas/m 2 …

In the computational particle fluid dynamics method, a numerical model of a three-dimensional circulating fluidized bed (CFB) air-water vapor mixture was established. This model facilitated an investigation of the characteristics of the biomass gasification process in a CFB gasifier. This study systematically examined the impact of variables …

Introduction. Circulating-fluidized-bed (CFB) technology has been used in various chemical processes, such as fluid catalytic cracking, coal combustion and gasification, and biomass treatment because of its ability to achieve a high-throughput operation, an efficient heat distribution, and efficient contact between gas and solids …

DEVELOPMENT OF A CIRCULATING FLUIDIZED BED REACTOR MODEL FOR THE FAST PYROLYSIS OF BIOMASS FOR PROCESS SIMULATION by Anna A. Trendewicz. A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of Mines in partial ful llment of the requirements for the degree of Doctor of Philosophy

Gas-solid fluidized beds have drawn the attention of engineers and researchers as an effective technology for a large variety of applications, and num…

In this paper, we developed a detailed process model to evaluate the potential of heat generation from biomass combustion in a CFB (circulating fluidized bed) combustor by coupling Aspen Plus ...

The clustering phenomenon in gas-solids high-density (Gs ≥ 300 kg/m²s) and low-density circulating fluidized bed (CFB) risers for FCC particles are compared through CFD studies using a cluster ...