Numerical Simulation of the Combustion Behavior of Different Biomasses in a Bubbling Fluidized Bed Boiler

2005 ◽  
Author(s):  
Christian Mueller ◽  
Anders Brink ◽  
Mikko Hupa
Keyword(s):  
Fluidized Bed ◽  
Power Plants ◽  
Thermal Power ◽  
Combustion Process ◽  
Fluidised Bed ◽  
Simplified Approach ◽  
Combustion Behavior ◽  
Bubbling Bed ◽  
Bubbling Fluidized Bed ◽  
Fuel Mixtures

Solid fuels currently used for energy production in thermal power plants are characterized by a large variety ranging from different coals to biomasses and wastes. This manifold of fuels offers opportunities to the energy producers and nowadays many power plants do not fire single fuels but fuel mixtures. While this procedure may lead to overall economic and environmental advantages it is very demanding for the boiler operators to maintain boiler performance and availability and to meet emission limits. The development of mathematical models that are capable of predicting the combustion behavior of fuel mixtures and provide guidelines for operators and manufacturers has been a challenge over the last years. Since bubbling fluidized beds are frequently used for firing fuel mixtures and especially biomass mixtures, current CFD based BFB models, such as the A˚bo Akademi Furnace Model, have been used widely over the last years to predict emission tendencies and ash deposition behavior. However, due to the complexity of the processes during combustion of fuel mixtures and the combustion process in the bubbling fluidised bed itself, the models are characterized by strong simplifications. This is especially true for the description of the lower part of the furnace, the region of fuel intake and bubbling bed. Recently, the A˚bo Akademi Furnace Model has been extended by a more detailed description of the fuel conversion by considering the combustion of individual biomass particles and a first simplified approach describing heat and mass transfer processes between the bubbling bed and the freeboard. Both submodels guarantee a closed mass and energy balance over the bed-freeboard region. In the current study the new submodels have been used to investigate the combustion conditions in a 290 MW bubbling fluidized bed boiler firing peat and forest residue. Clear differences in the simulation results for the both fuels can be found with regard to the specific combustion characteristics, the location of the main combustion zone and the total heat generated during combustion.

scholarly journals Composition and Morphology Characteristics of Magnetic Fractions of Coal Fly Ash Wastes Processed in High-Temperature Exposure in Thermal Power Plants

2019 ◽  
Vol 9 (9) ◽  
pp. 1964 ◽  
Author(s):  
Dinh-Hieu Vu ◽  
Hoang-Bac Bui ◽  
Bahareh Kalantar ◽  
Xuan-Nam Bui ◽  
Dinh-An Nguyen ◽  
...  
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Coal Fly Ash ◽  
Thermal Power ◽  
Combustion Process ◽  
Mineralogical Composition ◽  
Striking Difference ◽  
Thermal Power Plants ◽  
Power Stations ◽  
Magnetic Components

Coal-fired power stations are one of the primary sources of power generation in the world. This will produce considerable amounts of fly ash from these power stations each year. To highlight the potential environmental hazards of these materials, this study is carried out to evaluate the characterization of fly ashes produced in thermal power plants in northern Vietnam. Fly ash was firstly fractionated according to size, and the fractions were characterized. Then, each of these fractions was analyzed with regard to their mineralogical features, morphological and physicochemical properties. The analytical results indicate a striking difference in terms of the characteristics of particles. It was found that magnetic fractions are composed of magnetite hematite and, to a lower rate, mullite, and quartz. Chemical analyses indicate that the non-magnetic components mainly consist of quartz and mullite as their primary mineral phases. As the main conclusion of this research, it is found that the magnetic and non-magnetic components differ in terms of shape, carbon content and mineralogical composition. In addition, it was found that magnetic components can be characterized as more spheroidal components compared to non-magnetic ones. This comprehensive characterization not only offers a certain guideline regarding the uses of different ash fractions but it will also provide valuable information on this common combustion process.

The Suitability of Fly Ash for Use in Concrete According to EN 450 Based on their Particle Size

2018 ◽  
Vol 276 ◽  
pp. 110-115
Author(s):  
Martin Ťažký ◽  
Martin Labaj ◽  
Rudolf Hela
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Catalytic Reduction ◽  
Raw Materials ◽  
Thermal Power ◽  
Combustion Process ◽  
Thermal Power Plants ◽  
Mechanical Parameters ◽  
Fly Ashes ◽  
The Impact

The by-products of energy industry are nowadays often affected by new limits governing the production of harmful gases discharged into the air. These stricter and stricter criteria are often met by electricity producers by changing the combustion process in thermal power plants itself. Nowadays, the SNCR (selective non-catalytic reduction) application is quite common in the combustion process in order to help reduce the nitrogen oxide emission. This article deals with the primary measures of thermal power plants, which in particular consist of a modified treatment of raw materials (coal) entering the combustion process. These primary measures then often cause the formation of fly ash with unsuitable fineness for the use in concrete according to EN 450. The paper presents the comparison of the physico-mechanical parameters of several fly ashes with a different fineness values. The primary task is to assess the impact of non-suitable granulometry in terms of EN 450 on the other physico-mechanical parameters of fly ashes sampled within the same thermal power plant. Several fly ashes produced in the Czech Republic and surrounding countries were evaluated in this way.

CFD Based Ash Deposition Prediction in a BFB Firing Mixtures of Peat and Forest Residue

2003 ◽  
Author(s):  
Christian Mueller ◽  
Dan Lundmark ◽  
Bengt-Johan Skrifvars ◽  
Rainer Backman ◽  
Maria Zevenhoven ◽  
...  
Keyword(s):  
Combustion Chamber ◽  
Computational Fluid Dynamic ◽  
Power Plants ◽  
Fossil Fuels ◽  
Fluid Dynamic ◽  
Thermal Power ◽  
Biomass Combustion ◽  
Mineral Matter ◽  
Forest Residue ◽  
Bubbling Fluidized Bed

Fuels currently used for energy production in thermal power plants are characterized by their huge variety ranging from fossil fuels to biomass and waste. This multitude of fuels offers opportunities to the energy industry and nowadays many power plants do not fire either of these fuels but mixtures of them are burnt. While this procedure may lead to overall economic and environmental advantages it is very demanding for the boiler operators to still meet expectations concerning boiler performance, boiler availability and emission regulations. In the course of this latest trend in boiler operation, ash related operational problems such as slagging, fouling and corrosion are ranking very high on the list of reasons leading to significant reduction of boiler availability. Ash related problems strongly dependent on fuel specific aspects, such as the mineral matter distribution in the fuel, aspects specific to the used combustion technique as well as design aspects unique for the combustion chamber of any operating power plant. The overall goal in combustion related research is therefore the prediction of potential operational problems originating from fuel streams entering the combustion chamber as well as those originating from the design of individual furnaces. In our earlier work we have strongly focused on developing an advanced ash behavior prediction tool for biomass combustion combining computational fluid dynamic calculations (CFD) and advanced fuel analysis. In this paper the tool is applied to analyze the slagging and fouling tendency in a 295 MW bubbling fluidized bed boiler fired with mixtures of peat and forest residue. In addition to the overall deposition prediction this work focuses on details of the models used in the computational fluid dynamic calculations. These include a study on the importance of the accurate description of the fuel feeding system and related to this aspect the advanced description of the bubbling bed with regard to release of primary gas and ash particles from its surface to the freeboard. Evaluation of the predictions comparing simulation results with deposits on the furnace walls show good agreement.

scholarly journals Phosphorus-Rich Ash from Poultry Manure Combustion in a Fluidized Bed Reactor

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 785
Author(s):  
Zdzisław Adamczyk ◽  
Magdalena Cempa ◽  
Barbara Białecka
Keyword(s):  
Phase Composition ◽  
Fluidized Bed ◽  
Combustion Process ◽  
Poultry Manure ◽  
Raw Material ◽  
Process Efficiency ◽  
Chemical Components ◽  
Bubbling Fluidized Bed ◽  
Laboratory Reactor ◽  
Size And Morphology

The aim of this study was to examine the physico-chemical and phase characteristics of ash obtained in the process of the combustion of Polish poultry manure in a laboratory reactor with a bubbling fluidized bed. Three experiments, differing in the grain size and morphology of the raw material, the method of its dosing and the type of fluidized bed, were carried out. The contents of the main chemical components and trace elements in the obtained ash samples were determined using WDXRF, and the phase composition was examined through the XRD method. The morphology and the chemical composition of grains in a given micro-area using the SEM/EDS method were also investigated. The highest concentration of phosphorus (from 28.07% wt. to 29.71% wt. as P2O5 equivalent), the highest proportion of amorphous substance (from 56.7% wt. to 59.0% wt.) and the lowest content of unburned organic substance (LOI from 6.42% to 9.16%) (i.e., the best process efficiency), was obtained for the experiment in which the starting bed was quartz sand and poultry manure was fed to the reactor in the form of pellets. It has been calculated that in this case, the amorphous phase contains more than half of the phosphorus. The method of carrying out the combustion process has a significant impact on the phase composition and, consequently, on the availability of phosphorus.

scholarly journals Controlling the Combustion Process of Thermal Power Plants to Reduce the Amount of Carbon Dioxide Produced

2016 ◽  
Vol 10 (10) ◽  
pp. 1-12
Author(s):  
Roshdy AbdelRassoul ◽  
S. IEEE ◽  
Mohamed Zaghloul ◽  
Mohamed Omar ◽  
Islam El Adly
Keyword(s):  
Carbon Dioxide ◽  
Power Plants ◽  
Thermal Power ◽  
Combustion Process ◽  
Thermal Power Plants

Investigation of the Suitability of Serbian Lignites for Burning in CFBC Boilers

2005 ◽  
Author(s):  
S. Oka ◽  
B. Grubor ◽  
D. Dakic´ ◽  
M. Ilic´ ◽  
V. Manovic´ ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Electric Power ◽  
Fluidized Bed ◽  
Power Plants ◽  
Thermal Power ◽  
Power Production ◽  
Thermal Engineering ◽  
Electric Power Production ◽  
Production Company

The results of the detailed investigations of behavior of lignites Kolubara and Kovin, in fluidized bed combustion are presented in the paper. Investigation was carried out due to the interest of the Serbian Electric Power Production Company to use CFBC boilers in the process of refurbishment of old pulverized coal combustion boilers. As a part of a feasibility study for CFBC use in power plants in Serbia, investigation of combustion characteristics of lignites was performed using original methodology introduced many years ago by Laboratory for Thermal Engineering and Energy. Methodology was approved by numerous investigations of more than 20 Yugoslav coals for FBC combustion, with the aim to determine design data for bubbling FBC boilers. The main attention in present investigation was paid to the problem of using methodology developed for bubbling FBC in the conditions present in CFBC boilers. Four samples of Kolubara lignite, with heat capacity from 2.5 to 8.5 MJ/kg, and different ash contents were investigated, and also lignite Kovin in the same range of heat capacity. Investigations were performed in three phases: (1) ultimate and proximate analysis, determination of ash sintering temperature by standard method and in fluidized bed laboratory oven, (2) investigations in laboratory fluidized bed furnace and determination of coal particle fragmentation, burning rate, start-up temperature and self-sulfure-capture and (3) investigation of combustion in pilot-plant in stationary combustion conditions. In conclusion, suitability of results obtained in BFBC conditions is approved, and earlier statement that lignites are suitable for BFBC is confirmed by the statement that lignites are even more suitable for burning in CFBC boilers. Considering differences between combustion and flow conditions in bubbling and circulating FBC boilers, behavior of the lignites in CFBC is discussed in details and optimal regime parameters of the CFBC boilers are determined. The results obtained will be used by Serbian Electric Power Production Company for evaluation of bid for CFBC boiler implementation in refurbishment of old thermal power plants.

The Indirectly Heated Carbonate Looping Process for CO2 Capture—A Concept With Heat Pipe Heat Exchanger

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Daniel Hoeftberger ◽  
Juergen Karl
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Power Plants ◽  
Batch Reactor ◽  
Heat Pipes ◽  
Experimental Investigations ◽  
Transfer Coefficients ◽  
Carbonation Reaction ◽  
Heat Transfer Coefficients ◽  
Bubbling Fluidized Bed

The carbonate looping process using the reversible calcination/carbonation reaction of limestone is a promising way to reduce CO2 emissions of fossil fired power plants. This paper describes the concept of an indirectly heated version of this process in which heat pipes accomplish the heat transfer from an air-blown fluidized bed combustor to a bubbling fluidized bed calciner. It defines the calciner's specific heat demand which is a pendant to the heating value of coal. The dimensioning depends on the processes inside heat pipes as well as heat transfer of immersed heating surfaces. Experimental investigations in an electrically heated batch reactor with a similar pipe grid provide heat transfer coefficients under calcination conditions.

Chemical Intervention Combustion and Applications in Coal Saving and Reducing Emissions

2012 ◽  
Vol 512-515 ◽  
pp. 1106-1112
Author(s):  
Da Wei Hu ◽  
Yan Min Wang ◽  
Ai Zhi Yu
Keyword(s):  
Coal Combustion ◽  
Power Plants ◽  
Fossil Fuels ◽  
Greenhouse Gas Emission ◽  
Global Climate ◽  
Thermal Power ◽  
Combustion Process ◽  
Calorific Value ◽  
Combustion Method ◽  
Nonrenewable Resource

Coal as the world's most widely used fossil fuels, during the combustion process large amounts of greenhouse gas emission, which has a huge impact on global climate warming. However, coal is a nonrenewable resource, and the energy conservation is imperative. This paper, through analyzed the essential of coal combustion, and the feasibility and means for coal saving by using chemical intervention combustion. After tested the practical effects of chemical intervention coal combustion catalyst, which provided by Guangzhou Fenfang Environmental Protection Technology Co., Ltd. The results shown, the as received basis net calorific value at constant volume of the selected coal sample improved 8% which was tested by an oxygen bomb calorimeter, almost 1/6 sulfur was fixed in the cinder and the practical application coal saving effects in new dry rotary kilns and thermal power plants were more than 6%. Therefore, the chemical intervention combustion method has important significance in research and practical for coal saving and reducing emissions of pollutants.

scholarly journals Influence of the Fly Ash Material Inoculants on the Tensile and Impact Characteristics of the Aluminum AA 5083/7.5SiC Composites

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2452
Author(s):  
Santhosh Nagaraja ◽  
Kempaiah Ujjaini Nagegowda ◽  
Anand Kumar V ◽  
Sagr Alamri ◽  
Asif Afzal ◽  
...  
Keyword(s):  
Fly Ash ◽  
Impact Strength ◽  
Grain Refinement ◽  
Power Plants ◽  
Large Scale ◽  
Thermal Power ◽  
Combustion Process ◽  
Stir Casting ◽  
X Rays ◽  
Impact Characteristics

The choice of suitable inoculants in the grain refinement process and subsequent enhancement of the characteristics of the composites developed is an important materials research topic, having wide scope. In this regard, the present work is aimed at finding the appropriate composition and size of fly ash as inoculants for grain refinement of the aluminum AA 5083 composites. Fly ash particles, which are by products of the combustion process in thermal power plants, contributing to the large-scale pollution and landfills can be effectively utilized as inoculants and interatomic lubricants in the composite matrix–reinforcement subspaces synthesized in the inert atmosphere using ultrasonic assisted stir casting setup. Thus, the work involves the study of the influence of percentage and size of the fly ash dispersions on the tensile and impact strength characteristics of the aluminum AA 5083/7.5SiC composites. The C type of fly ash with the particle size in the series of 40–75 µm, 76–100 µm, and 101–125 µm and weight % in the series of 0.5, 1, 1.5, 2, and 2.5 are selected for the work. The influence of fly ash as distinct material inoculants for the grain refinement has worked out well with the increase in the ultimate tensile strength, yield strength, and impact strength of the composites, with the fly ash as material inoculants up to 2 wt. % beyond which the tensile and impact characteristics decrease due to the micro coring and segregation. This is evident from the microstructural observations for the composite specimens. Moreover, the role of fly ash as material inoculants is distinctly identified with the X-Ray Diffraction (XRD) for the phase and grain growth epitaxy and the Energy Dispersive Spectroscopy (EDS) for analyzing the characteristic X-Rays of the fly ash particles as inoculant agents in the energy spectrum.

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