scholarly journals Comprehensive Simulator (CSFMB) Applied to Circulating Fluidized Bed Boilers and Gasifiers

2008 ◽  
Vol 2 (1) ◽  
pp. 106-118 ◽  
Author(s):  
Marcio L. de Souza-Santos
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Circulating Fluidized Bed ◽  
Scaling Up ◽  
Simulation Program ◽  
Circulating Fluidized Beds ◽  
Simulation Results ◽  
Fluidized Bed Boilers ◽  
Operational Data ◽  
Industrial Units

A comprehensive simulation program of bubbling fluidized beds (CSFB or CSFMB) has been able to reproduce operations of circulating fluidized beds. The main considerations that allow such application as well comparisons between simulation results and real operational data are shown. In addition, criteria for scaling-up pilot operations to industrial units are illustrated.

Scaling of flow phenomena in circulating fluidized bed boilers

2011 ◽  
Vol 32 (2) ◽  
pp. 91-100 ◽  
Author(s):  
Paweł Mirek
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Circulating Fluidized Bed ◽  
Scaling Law ◽  
Governing Equations ◽  
Dimensionless Numbers ◽  
Hydrodynamic Parameters ◽  
Scaling Models ◽  
Flow Phenomena ◽  
Fluidized Bed Boilers

Scaling of flow phenomena in circulating fluidized bed boilers The paper presents an overview of scaling models used for determining hydrodynamic parameters of Circulating Fluidized Bed boilers. The governing equations and the corresponding dimensionless numbers are derived and presented for three different approaches to the scaling law of fluidized beds: classical dimensional analysis, differential equations and integrated solutions and experimental correlations. Some results obtained with these equations are presented. Finally, the capabilities and limitations of scaling experiments are discussed.

scholarly journals Effects of biomass on dynamics of combustion in circulating fluidized beds

2004 ◽  
Vol 8 (2) ◽  
pp. 93-106 ◽  
Author(s):  
Antti Tourunen ◽  
Heidi Häsä ◽  
Juha Pitsinki ◽  
Mikko Jegoroff ◽  
Jaakko Saastamoinen ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Fluidized Beds ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Fluidized Bed Reactor ◽  
High Reactivity ◽  
Limiting Factor ◽  
Circulating Fluidized Beds ◽  
Process Stability ◽  
Boiler Operation

Fluidized bed technology is very suitable for the combustion of biomass Nevertheless substitution of coal with biomass affects boiler operation and especially dynamics and controllability. Non-homogeneity of biomass and fuel feeding disturbances cause process instability, such as variations in temperatures and pressures, which reduce lifetime of equipment and structures. Because of process instability higher air coefficient must be used in order to avoid CO emissions, which is not economical. Combustion profiles for coal, wood and peat, measured at the VTT Processes Pilot circulating fluidized bed reactor, have been compared. Process stability and char inventories have been studied by the measurements and the model. Biofuel are usually very reactive and their combustion profiles are quite different compared to coals. Because of high reactivity and low char content combustion process with biofuel is very sensitive for fuel feeding. Also low char inventory effect on load changes combined with combustion profile that differs from coals. Because of different combustion profile heat transfer can be a limiting factor in load changes despite the high reactivity and fast oxygen response.

scholarly journals Modelling of dynamics of combustion of biomass in fluidized beds

2004 ◽  
Vol 8 (2) ◽  
pp. 107-126 ◽  
Author(s):  
Jaakko Saastamoinen
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Fuel Mixture ◽  
Linear Increase ◽  
Fuel Feed ◽  
New Process ◽  
Fuel Particles ◽  
The Stability ◽  
Fluidized Bed Boilers

New process concepts in energy production and biofuel, which are much more reactive than coal, call for better controllability of the combustion in circulating fluidized bed boilers. Simplified analysis describing the dynamics of combustion in fluidized bed and circulating fluidized bed boilers is presented. Simple formulas for the estimation of the responses of the burning rate and fuel inventory to changes in fuel feeding are presented. Different changes in the fuel feed, such as an impulse, step change, linear increase and cyclic variation are considered. The dynamics of the burning with a change in the feed rate depends on the fuel reactivity and particle size. The response of a fuel mixture with a wide particle size distribution can be found by summing up the effect of different fuel components and size fractions. Methods to extract reaction parameters form dynamic tests in laboratory scale reactors are discussed. The residence time of fuel particles in the bed and the resulting char inventory in the bed decrease with increasing fuel reactivity and differences between coal and biomass is studied. The char inventory affects the stability of combustion. The effect of char inventory and oscillations in the fuel feed on the oscillation of the flue gas oxygen concentration is studied by model calculation. A trend found by earlier measurements is explained by the model.

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