scholarly journals Application of circulating fluidized bed boilers in the fuel combustion process

2018 ◽  
Vol 4 ◽  
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Fuel Combustion ◽  
Fluidized Bed Boilers

Research on coal-water fuel combustion in a circulating fluidized bed / Badanie spalania zawiesinowych paliw węglowo-wodnych w cyrkulacyjnej warstwie fluidalnej

2012 ◽  
Vol 57 (1) ◽  
pp. 79-92
Author(s):  
Agnieszka Kijo-Kleczkowska
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Fuel Combustion ◽  
Waste Materials ◽  
Inert Material ◽  
Process Conditions ◽  
Heat And Mass Exchange ◽  
Water Suspension ◽  
Power Stations

In the paper the problem of heavily-watered fuel combustion has been undertaken as the requirements of qualitative coals combusted in power stations have been growing. Coal mines that want to fulfill expectations of power engineers have been forced to extend and modernize the coal enrichment plants. This causes growing quantity of waste materials that arise during the process of wet coal enrichment containing smaller and smaller under-grains. In this situation the idea of combustion of transported waste materials, for example in a hydraulic way to the nearby power stations appears attractive because of a possible elimination of the necessary deep dehydration and drying as well as because of elimination of the finest coal fraction loss arising during discharging of silted water from coal wet cleaning plants. The paper presents experimental research results, analyzing the process of combustion of coal-water suspension depending on the process conditions. Combustion of coal-water suspensions in fluidized beds meets very well the difficult conditions, which should be obtained to use the examined fuel efficiently and ecologically. The suitable construction of the research stand enables recognition of the mechanism of coal-water suspension contact with the inert material, that affects the fluidized bed. The form of this contact determines conditions of heat and mass exchange, which influence the course of a combustion process. The specificity of coal-water fuel combustion in a fluidized bed changes mechanism and kinetics of the process.

scholarly journals Developments in fluidized bed conversion of solid fuels

2016 ◽  
Vol 20 (suppl. 1) ◽  
pp. 1-18 ◽  
Author(s):  
Bo Leckner
Keyword(s):  
Fluidized Bed ◽  
Co2 Capture ◽  
Circulating Fluidized Bed ◽  
Fuel Combustion ◽  
Solid Fuels ◽  
Important Development ◽  
Bubbling Beds ◽  
Fluidized Bed Boilers ◽  
Development Tasks

A summary is given on the development of fluidized bed conversion (combustion and gasification) of solid fuels. First, gasification is mentioned, following the line of development from the Winkler gasifier to recent designs. The combustors were initially bubbling beds, which were found unsuitable for combustion of coal because of various drawbacks, but they proved more useful for biomass where these drawbacks were absent. Instead, circulating fluidized bed boilers became the most important coal converters, whose design now is quite mature, and presently the increments in size and efficiency are the most important development tasks. The new modifications of these conversion devices are related to CO2 capture. Proposed methods with this purpose, involving fluidized bed, are single-reactor systems like oxy-fuel combustion, and dual-reactor systems, including also indirect biomass gasifiers.

Design Considerations of Oxy-Fuel Fired Supercritical Pressure Circulating Fluidized Bed Boilers

2006 ◽  
Author(s):  
Prabir K. Halder
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Flue Gas ◽  
Circulating Fluidized Bed ◽  
Fuel Combustion ◽  
Cfb Boiler ◽  
Design Considerations ◽  
Effective Manner ◽  
The Impact ◽  
Fluidized Bed Boilers

Researchers around the globe are focussing on the capture and storage of carbon dioxide generated from the combustion of coal in boilers for power generation. Oxygen fired boilers have the advantage of creating CO2 rich flue gas which enables the CO2 to be captured in a more cost effective manner compared to post combustion capture of CO2 from an air fired boiler. This paper discusses design considerations for oxy-fuel fired supercritical circulating fluidized bed boilers. A 420 MWe supercritical CFB boiler firing coal with oxygen has been considered for the study. An analytical/semi-empirical model has been developed to model fuel combustion and heat transfer in the furnace and convection pass. The fuel burns with oxygen supplied at the bottom of the bed and the fluidization velocity and bed temperature is controlled by flue gas recirculation. The model is used to design the boiler and determine its performance characteristics. The heating surfaces, recirculation ratios and other parameters have been designed to achieve the required boiler capacity. The impact of the CO2 rich flue gas on CFB boiler design is compared with conventional air blown CFB boilers. The study reveals that oxy-fuel combustion in a CFB combustor does not alter the heat transfer characteristics when compared with combustion with air. In the convection bank, oxyfuel combustion increases both convective and radiative components of heat transfer, thereby reducing the size of the heat transfer banks required.

scholarly journals Analysis of cyclic combustion of the coal-water suspension

2011 ◽  
Vol 32 (1) ◽  
pp. 45-75 ◽  
Author(s):  
Agnieszka Kijo-Kleczkowska
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Fuel Combustion ◽  
Technical Application ◽  
Water Suspension ◽  
Depth Analysis ◽  
Combustion Technology ◽  
Cyclic Changes ◽  
The Mathematical Model

Analysis of cyclic combustion of the coal-water suspension Combustion technology of the coal-water suspension creates a number of new possibilities to organize the combustion process fulfilling contemporary requirements, e.g. in the environment protection. Therefore the in-depth analysis is necessary to examine the technical application of coal as a fuel in the form of suspension. The research undertakes the complex investigations of the continuous coal-water suspension as well as cyclic combustion. The cyclic nature of fuel combustion results from the movement of the loose material in the flow contour of the circulating fluidized bed (CFB): combustion chamber, cyclone and downcomer. The experimental results proved that the cyclic change of oxygen concentration around fuel, led to the vital change of both combustion mechanisms and combustion kinetics. The mathematical model of the process of fuel combustion has been presented. Its original concept is based on the allowance for cyclic changes of concentrations of oxygen around the fuel. It enables the prognosis for change of the surface and the centre temperatures as well as mass loss of the fuel during combustion in air, in the fluidized bed and during the cyclic combustion.

Modeling of Solid Fuel Combustion in Furnaces with a Circulating Fluidized Bed

2008 ◽  
Vol 39 (1) ◽  
pp. 65-78
Author(s):  
Yu. S. Teplitskii ◽  
V. A. Borodulya ◽  
V. I. Kovenskii ◽  
E. P. Nogotov
Keyword(s):  
Fluidized Bed ◽  
Solid Fuel ◽  
Circulating Fluidized Bed ◽  
Fuel Combustion ◽  
Solid Fuel Combustion

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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