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 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.

scholarly journals Analysis and Discussion on Burning Low Calorific Value Fuel of Circulating Fluidized Bed Boiler

2021 ◽  
Vol 329 ◽  
pp. 01074
Author(s):  
Yi Yan
Keyword(s):  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
High Reliability ◽  
Combustion Process ◽  
Calorific Value ◽  
Utilization Rate ◽  
Energy Structure ◽  
Actual Process ◽  
Circulating Fluidized Bed Boiler ◽  
Power Stations

China's coal-dominated energy structure will not change in a short time. In order to implement the relevant national policies on energy conservation and emission reduction, it is a good response to adopt circulating fluidized bed boilers in coal-fired power stations. Circulating fluidized bed boiler adopts fluidized combustion, which has high reliability and high utilization rate because of its special combustion mode and particle recycling device. For the low calorific value inferior fuel which is difficult to burn in common boiler, CFB boiler also has certain adaptability and compatibility. In this background, this article with coal gangue as the representative of the inferior coal are discussed its application in the circulating fluidized bed boiler, the combustion process, boiler equipment and special fly ash produced by combustion is proposed that often appear in the three aspects of problems, and accordingly put forward the solution and optimization measures, provides reference for the actual process.

Three-Dimensional Modeling and Model Validation of Circulating Fluidized Bed Combustion

2003 ◽  
Author(s):  
Kari Myo¨ha¨nen ◽  
Timo Hyppa¨nen ◽  
Jouni Miettinen ◽  
Riku Parkkonen
Keyword(s):  
Heat Flux ◽  
Fluidized Bed ◽  
Large Scale ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Three Dimensional ◽  
Hot Water ◽  
Combustion Model ◽  
Process Conditions ◽  
Model Parameters

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 the hydrodynamics of the bed, devolatilization of fuel, combustion of char, combustion of hydrocarbons, carbon monoxide and hydrogen, calcination and sulfation, fragmentation and attrition of solids, heat transfer, overall mass balance of the furnace, and three-dimensional balance equations based on the finite volume method. The code was initially developed in 1989, and it has been updated and improved over the years as new methods and new information have become available. The model is used for increasing process knowledge and for studying such phenomena inside the furnace which are often difficult or impossible to study by direct measurements. The knowledge obtained is then applied to optimize boiler design and process performance in terms of efficiency, economy and environmental issues. Reliable experiments and measurements in commercial boilers are used for the validation of the model and for tuning the model parameters. For the validation of a three-dimensional model, extensive profile measurements of the various parts of the furnace are required. This paper presents validation studies for an 80 MWth hot water boiler burning bituminous coal and for a 235 MWe subcritical boiler burning lignite. The measurements with these units included profile measurements of heat flux, pressure, temperature and gas composition under different process conditions. The model was tuned according to the measurements and used for the prediction of the heat flux profile of a large scale supercritical CFB boiler.

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

Numerical simulation of circulating fluidized bed oxy-fuel combustion with Dense Discrete Phase Model

2019 ◽  
Vol 195 ◽  
pp. 106129 ◽  
Author(s):  
Ying Wu ◽  
Daoyin Liu ◽  
Dong Zheng ◽  
Jiliang Ma ◽  
Lunbo Duan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Fuel Combustion ◽  
Phase Model ◽  
Discrete Phase Model ◽  
Discrete Phase

scholarly journals Oxy-combustion of biomass in a circulating fluidized bed

2016 ◽  
Vol 37 (1) ◽  
pp. 17-30 ◽  
Author(s):  
Monika Kosowska-Golachowska ◽  
Agnieszka Kijo-Kleczkowska ◽  
Adam Luckos ◽  
Krzysztof Wolski ◽  
Tomasz Musiał
Keyword(s):  
Fluidized Bed ◽  
Ignition Temperature ◽  
Loss Rate ◽  
Circulating Fluidized Bed ◽  
Mass Loss Rate ◽  
Thermal Analyses ◽  
Combustion Process ◽  
Combustion Characteristics ◽  
Lower Maximum ◽  
Maximum Mass Loss

Abstract The objective of this study was to investigate combustion characteristics of biomass (willow, Salix viminalis) burnt in air and O2/CO2 mixtures in a circulating fluidized bed (CFB). Air and oxy-combustion characteristics of wooden biomass in CFB were supplemented by the thermogravimetric and differential thermal analyses (TGA/DTA). The results of conducted CFB and TGA tests show that the composition of the oxidizing atmosphere strongly influences the combustion process of biomass fuels. Replacing N2 in the combustion environment by CO2 caused slight delay (higher ignition temperature and lower maximum mass loss rate) in the combustion of wooden biomass. The combustion process in O2/CO2 mixtures at 30% and 40% O2 is faster and shorter than that at lower O2 concentrations.

scholarly journals Experimental determination of a mass loss of biomass pellets at different temperatures of the combustion chamber combusted in a stream of inert material

2019 ◽  
Vol 82 ◽  
pp. 01007
Author(s):  
Katarzyna Kaczyńska ◽  
Konrad Kaczyński ◽  
Piotr Pełka
Keyword(s):  
Mass Loss ◽  
Combustion Chamber ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Inert Material ◽  
Mass Rate ◽  
Different Temperatures

In the herein paper, research on the mass loss of biomass pellets is presented. The research was carried out on a specially constructed test stand. In the research three types of pellet fuels were used, which were made of oak sawdust, sunflower husk and straw. The research was carried out at three different temperatures of the combustion chamber: 850°C, 750°C and 650°C. The research was carried out without inert material and mass rate flow Gs=2,5kg/m2s and Gs=5kg/m2s. Quartz sand was the inert material. It was expected that an increase in the temperature prevailing in the combustion chamber would accelerate the process of mass loss of the biomass pellet combustion. However, the results of the experiment indicated that this is not the case in every analyzed case. The mass flow rate of inert material intensifies the combustion process and accelerates the biomass pellets made of oak sawdust mass loss, but increasing the temperature in the combustion chamber accelerates the process of biomass pellets mass loss more than the mass flow rate of inert material. Based on the experimental tests carried out, it was found that biomass can be combusted in circulating fluidized bed boilers, albeit due to the diversified chemical composition of the biomass (alkali content), the boiler should be operated in such a way as to prevent the softening and melting temperature of the ash being exceeded.

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