Modelling Fuel and Sorbent Attrition During Circulating Fluidized Bed Combustion of Coal

2003 ◽  
Author(s):  
D. Barletta ◽  
A. Marzocchella ◽  
P. Salatino ◽  
S. G. Kang ◽  
P. T. Stromberg
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Surface Wear ◽  
Fluidized Bed Combustion ◽  
Coal Fuel ◽  
Primary Fragmentation ◽  
The Impact ◽  
Constitutive Parameters ◽  
Fluidized Bed Combustor ◽  
Circulating Fluidized Bed Combustion

A simulation model of a circulating fluidized bed combustor, based on a one-dimensional description of bed hydrodynamics and a simplified formulation of the population balance equation on fuel and bed solids, has been set up. The model specifically aims at assessing the extent of fuel and sorbent attrition during circulating fluidized bed combustion of coal. Fuel attrition is modelled as a function of carbon loading and of the relevant operating variables while taking into account primary fragmentation of coal and secondary fragmentation and attrition by surface wear of its char. Modelling of sorbent attrition accounts for primary fragmentation of limestone upon calcination as well as attrition by surface wear of lime. To this end time- and conversion-dependent attrition rate is averaged over the sorbent particle lifetime in the reactor. Attrition submodels and their constitutive parameters are based on previous work by the research group in Naples. Coal char combustion and lime sulphation are modelled considering intrinsic reaction kinetics as well as boundary layer and intraparticle diffusion of reactants. The impact of attrition phenomena on the performance of the fluidized bed combustor is characterized by looking at carbon combustion efficiency, at sulphur capture efficiency, at the balance between bottom and fly ashes. The influence of operating parameters like fuel particle size, Ca/S ratio, gas superficial velocity, extent of air staging is investigated. The sensitivity of results of model computations to the parameters expressing fuel and sorbent attrition is presented and discussed.

Sulphur Oxidation States in Residues from a Small-Scale Circulating Fluidized Bed Combustor

1988 ◽  
Vol 136 ◽  
Author(s):  
E. E. Berry ◽  
R. T. Hemmings ◽  
B. J. Cornelius ◽  
E. J. Anthony
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Small Scale ◽  
Fluidized Bed Combustion ◽  
Sulphur Compounds ◽  
Combustion Gas ◽  
Gas Cleaning ◽  
Utility Scale ◽  
Fluidized Bed Combustor ◽  
Circulating Fluidized Bed Combustion

ABSTRACTSignificant concentrations (∼6%, as CaS) of sulphides or other reduced-sulphur species in solid residues from a small-scale circulating fluidized bed (CFB) combustor have been reported in the literature. The presence of sulphides in similar quantities in residues from a utility-scale combustor would present significant difficulties with handling, disposal or utilization of the residues. This paper discusses the preliminary findings of an investigation of sulphur capture in a small-scale circulating fluidized bed combustion (CFBC) unit using a limestone bed and burning a high-S, high-Fe, Eastern Canadian coal. Data are presented on sulphur capture and chemical speciation for residue samples taken from a number of locations in the circulating bed during operation. The results are discussed in terms of probable mechanisms for the formation of sulphur compounds of reduced oxidation state in the bed and the combustion-gas cleaning system.

Towards an Accurate Control of Circulating Fluidized Bed Combustor

2012 ◽  
Vol 466-467 ◽  
pp. 763-767
Author(s):  
Shi Li ◽  
Yan Hu ◽  
Xi Ju Zong
Keyword(s):  
Optimal Control ◽  
Fluidized Bed ◽  
Control Strategy ◽  
Circulating Fluidized Bed ◽  
Combustion Stability ◽  
Comparative Approach ◽  
Fluidized Bed Combustion ◽  
Control Laws ◽  
Fluidized Bed Combustor ◽  
Circulating Fluidized Bed Combustion

Circulating fluidized bed combustion is a widely used technology because of its ability to burn a wide variety of fuels efficiently and in an environmentally acceptable manner. To guarantee optimal combustion performances, combustion stability is essential. This paper proposes a comparative approach to define a suitable control strategy for an accurate control of fuel combustion. Several control laws are therefore defined and applied on a dynamic nonlinear model, based on a pilot plant and representative of the main combustion phenomena: a conventional PID, a linear optimal control, a robust H∞ approach and a nonlinear control.

scholarly journals Highly Effective Adsorption Process of Ni(II) Ions with the Use of Sewage Sludge Fly Ash Generated by Circulating Fluidized Bed Combustion (CFBC) Technology

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3106
Author(s):  
Tomasz Kalak ◽  
Kinga Marciszewicz ◽  
Joanna Piepiórka-Stepuk
Keyword(s):  
Fly Ash ◽  
Sewage Sludge ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Fluidized Bed Combustion ◽  
Nickel Ions ◽  
Suitable Material ◽  
Circulating Fluidized Bed Combustion

Recently, more and more attention has been paid to the removal of nickel ions due to their negative effects on the environment and human health. In this research, fly ash obtained as a result of incineration of municipal sewage sludge with the use of circulating fluidized bed combustion (CFBC) technology was used to analyze the possibility of removing Ni(II) ions in adsorption processes. The properties of the material were determined using analytical methods, such as SEM-EDS, XRD, BET, BJH, thermogravimetry, zeta potential, SEM, and FT-IR. Several factors were analyzed, such as adsorbent dose, initial pH, initial concentration, and contact time. As a result of the conducted research, the maximum sorption efficiency was obtained at the level of 99.9%. The kinetics analysis and isotherms showed that the pseudo-second order equation model and the Freundlich isotherm model best suited this process. In conclusion, sewage sludge fly ash may be a suitable material for the effective removal of nickel from wastewater and the improvement of water quality. This research is in line with current trends in the concepts of circular economy and sustainable development.

Utilization of Circulating Fluidized Bed Combustion (CFBC) Fly Ash and Coal-Fired Fly Ash in Portland Cement

2014 ◽  
Vol 629-630 ◽  
pp. 306-313 ◽  
Author(s):  
Mao Chieh Chi ◽  
Ran Huang ◽  
Te Hsien Wu ◽  
Toun Chun Fou
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Fluidized Bed ◽  
Building Materials ◽  
Circulating Fluidized Bed ◽  
Setting Time ◽  
Fluidized Bed Combustion ◽  
Initial Setting Time ◽  
Cfbc Fly Ash ◽  
Circulating Fluidized Bed Combustion

Circulating fluidized bed combustion (CFBC) fly ash is a promising admixture for construction and building materials due to its pozzolanic activity and self-cementitious property. In this study, CFBC fly ash and coal-fired fly ash were used in Portland cement to investigate the pozzolanic and cementitious characteristics of CFBC fly ash and the properties of cement-based composites. Tests show that CFBC fly ash has the potential instead of cementing materials and as an alternative of pozzolan. In fresh specimens, the initial setting time of mortars increases with the increasing amount of cement replacement by CFBC fly ash and coal-fire fly ash. In harden specimens, adding CFBC fly ash to replace OPC reduces the compressive strength. Meanwhile, CFBC fly ash would results in a higher length change when adding over 30%. Based on the results, the amount of CFBC fly ash replacement cement was recommended to be limited below 20%.

Influencing Factors of Hydraulic Property of CFBC Ashes

2012 ◽  
Vol 532-533 ◽  
pp. 282-286
Author(s):  
Yuan Ming Song ◽  
Jing Xiang Liu ◽  
Chao Wang ◽  
Hong He Zhong ◽  
Tian Ding
Keyword(s):  
High Activity ◽  
Fluidized Bed ◽  
Influencing Factors ◽  
Circulating Fluidized Bed ◽  
Great Influence ◽  
Fluidized Bed Combustion ◽  
Hydraulic Property ◽  
Free Lime ◽  
Circulating Fluidized Bed Combustion

The hydraulic property of Circulating Fluidized Bed Combustion (CFBC) ashes has a significant impact on their treatment and re-utilization. The studies on several CFBC ashes show that the hydraulic property of them is obvious, and even the hydraulic rate is so fast that CFBC pastes can harden within several hours after molding. The influencing factors of hydraulic property of CFBC ashes are investigated. The results confirm that the content of the free lime and the high-activity components has great influence on the hydraulic property of CFBC ashes.

Sign in / Sign up

Export Citation Format

Share Document