scholarly journals Specific Features of Solid Fuels Combustion in Oxygen Atmosphere with Recirculation of CO2

2015 ◽  
Vol 17 (3) ◽  
pp. 213
Author(s):  
D.A. Melnikov ◽  
G.A. Ryabov
Keyword(s):  
Coal Combustion ◽  
Carbon Capture ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Carbon Capture And Storage ◽  
Combustion Model ◽  
Coal Pyrolysis ◽  
Char Particle ◽  
Isothermal Kinetic ◽  
Gasification Reaction

<p>Aspects of coal combustion have been experimentally studied under oxyfuel conditions, one of the promising technologies for carbon capture and storage (CCS). Here, the thermogravimetric analysis (TGA) method was chosen as an experimental technique. Coal pyrolysis tests performed under an O<sub>2</sub>/CO<sub>2</sub> atmosphere were compared with a conventional O<sub>2</sub>/N<sub>2</sub> environment in terms of reaction rate and total volatile yield. Combustion of the resulting chars in the corresponding atmospheres revealed somewhat different combustion rates with a less vigorous reaction in the O<sub>2</sub>/CO<sub>2</sub> medium. The two manipulated factors – namely, the inherently different char reactivities due to the different atmospheres they were obtained in and the different atmospheres of the actual combustion process – were distinguished by performing another series of tests with chars pyrolysed under identical conditions using a standard routine. These chars also showed a weaker reaction in O<sub>2</sub>/CO<sub>2</sub> atmosphere, which was attributed to the lower binary diffusion coefficient of the O<sub>2</sub>/CO<sub>2</sub> pair. The activity of the char – CO<sub>2 </sub>gasification reaction in an O<sub>2</sub>/CO<sub>2</sub> environment was also investigated and revealed some contribution of this reaction to the conversion process. This was particularly noticeable at temperatures above 750 °C and under an internal diffusional controlled regime (zone II), implying displacement of oxygen out of the char particle pore volume, which allowed free reaction of CO<sub>2</sub> on the developed pore surface. Non-isothermal kinetic analysis of the intrinsic kinetics of the oxidation reaction in O<sub>2</sub>/CO<sub>2</sub> revealed no particular difference compared to the O<sub>2</sub>/N<sub>2</sub> medium, at least when the char-CO<sub>2 </sub>reaction was inhibited. The obtained data were used to develop a coal combustion model under O<sub>2</sub>/CO<sub>2</sub> conditions, which was then incorporated as a combustion module into circulating fluidized bed (CFB) computation software.</p>

scholarly journals Experimental and numerical investigation of flame characteristics during swirl burner operation under conventional and oxy-fuel conditions

2017 ◽  
Vol 21 (3) ◽  
pp. 1463-1477 ◽  
Author(s):  
Rastko Jovanovic ◽  
Krzysztof Strug ◽  
Bartosz Swiatkowski ◽  
Sławomir Kakietek ◽  
Krzysztof Jagiełło ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Coal Combustion ◽  
Carbon Capture ◽  
Low Cost ◽  
Combustion Process ◽  
Carbon Capture And Storage ◽  
Fuel Combustion ◽  
Pulverized Coal ◽  
Test Facility ◽  
Dual Mode

Oxy-fuel coal combustion, together with carbon capture and storage or utilization, is a set of technologies allowing to burn coal without emitting globe warming CO2. As it is expected that oxy-fuel combustion may be used for a retrofit of existing boilers, development of a novel oxy-burners is very important step. It is expected that these burners will be able to sustain stable flame in oxy-fuel conditions, but also, for start-up and emergency reasons, in conventional, air conditions. The most cost effective way of achieving dual-mode boilers is to introduce dual-mode burners. Numerical simulations allow investigation of new designs and technologies at a relatively low cost, but for the results to be trustworthy they need to be validated. This paper proposes a workflow for design, modeling, and validation of dual-mode burners by combining experimental investigation and numerical simulations. Experiments are performed with semi-industrial scale burners in 0.5 MWt test facility for flame investigation. Novel CFD model based on ANSYS FLUENT solver, with special consideration of coal combustion process, especially regarding devolatilization, ignition, gaseous and surface reactions, NOx formation, and radiation was suggested. The main model feature is its ability to simulate pulverized coal combustion under different combusting atmospheres, and thus is suitable for both air and oxy-fuel combustion simulations. Using the proposed methodology two designs of pulverized coal burners have been investigated both experimentally and numerically giving consistent results. The improved burner design proved to be a more flexible device, achieving stable ignition and combustion during both combustion regimes: conventional in air and oxy-fuel in a mixture of O2 and CO2 (representing dry recycled flue gas with high CO2 content). The proposed framework is expected to be of use for further improvement of multi-mode pulverized fuel swirl burners but can be also used for independent designs evaluation.

scholarly journals Integrated carbon capture and storage for an oxyfuel combustion process by using carbonation of Mg(OH)2 produced from serpentinite rock

2011 ◽  
Vol 4 ◽  
pp. 2839-2846 ◽  
Author(s):  
Arshe Said ◽  
Sanni Eloneva ◽  
Carl-Johan Fogelholm ◽  
Johan Fagerlund ◽  
Experience Nduagu ◽  
...  
Keyword(s):  
Carbon Capture ◽  
Combustion Process ◽  
Carbon Capture And Storage ◽  
Oxyfuel Combustion ◽  
And Storage

scholarly journals Oxyfuel Combustion of a Model MSW—An Experimental Study

Energies ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5297
Author(s):  
Michaël Becidan ◽  
Mario Ditaranto ◽  
Per Carlsson ◽  
Jørn Bakken ◽  
Maria N. P. Olsen ◽  
...  
Keyword(s):  
Carbon Capture ◽  
Combustion Process ◽  
Carbon Capture And Storage ◽  
Heat Power ◽  
Complete Combustion ◽  
Oxyfuel Combustion ◽  
Challenges And Opportunities ◽  
And Storage ◽  
Negative Co2 Emissions ◽  
Scale Reactor

The oxyfuel combustion of a model MSW (municipal solid waste) under various conditions was carried out in a lab-scale reactor. The aim was to study the behavior of MSW and identify challenges and opportunities associated with the development of this technology in the context of integration with CCS (carbon capture and storage). The experimental results show the effects of the oxidizer composition on the combustion process. Complete combustion can be attained under a variety of oxyfuel conditions, and the differences highlighted with O2/CO2 as an oxidizer compared with O2/N2 do not constitute showstoppers. MSW oxyfuel combustion hence offers a great potential for the combined (1) treatment of waste (contaminants’ destruction, volume, and weight reduction), (2) production of heat/power, and (3) CCS with negative CO2 emissions.

Pressurised Oxy-Coal Combustion Rankine-Cycle for Future Zero Emission Power Plants: Technological Issues

2009 ◽  
Author(s):  
Marco Gazzino ◽  
Giovanni Riccio ◽  
Nicola Rossi ◽  
Giancarlo Benelli
Keyword(s):  
Coal Combustion ◽  
Carbon Capture ◽  
Power Plants ◽  
Process Integration ◽  
Scale Up ◽  
Combustion Process ◽  
Rankine Cycle ◽  
Intermediate Step ◽  
Combustion Technology ◽  
Zero Emission

Among possible options to capture carbon dioxide, pressurised oxy-fuel combustion is a promising one. Accordingly, Enel teamed with Itea and Enea to develop a pressurised oxy-combustion technology. Currently, extensive tests have been carried out at 4 bar on a 5 MWt facility based in Gioia del Colle (Southern Italy). By starting from the know-how gained on that scale, Enel planned to build by 2010 an experimental 48 MWt demo-plant, based on the same pressurised combustion process introduced above. This will be the necessary intermediate step for the further scale-up towards a zero emission plant of industrial scale. This paper is the prosecution of a previous publication presenting the process design and energy analysis of a power cycle integrating the developed pressurised oxy-coal combustion technology with a Rankine cycle including carbon capture. After having briefly presented the pressurised oxycombustion project carried out at Enel, the paper focuses on technology issues related to the proposed cycle and the related process integration, with respect to main components.

Numerical Investigation of Char Reactivity in Oxy-Coal Combustion in Carbon Capture and Sequestration Technologies

2009 ◽  
Author(s):  
M. Gharebaghi ◽  
B. Goh ◽  
J. M. Jones ◽  
L. Ma ◽  
M. Pourkashanian ◽  
...  
Keyword(s):  
Coal Combustion ◽  
Carbon Capture ◽  
Fluid Dynamic ◽  
Substantial Reduction ◽  
Combustion Process ◽  
Test Facility ◽  
Cfd Modeling ◽  
Unburned Carbon ◽  
Char Reactivity ◽  
The Impact

Oxy-coal combustion with CO2 capture from flue gas is an emerging technology that can be adapted to both new and existing coal-fired power stations leading to substantial reduction in carbon emission from the power generation industry. However, switching to oxy-coal brings a number of uncertainties to the combustion process and there is a significant knowledge gap in this new technology. Computational Fluid Dynamic (CFD) studies can be used as one of the tool to identify the extent of the modifications required due to changes in the process. One of the possible challenges is related to the the changes in char combustion and char reactivity which may have an impact on unburned carbon in the furnace. In this study, two approaches have been undertaken to investigate the impact of oxy-coal combustion on char reactivity: simple equilibrium calculations and numerical 3-D simulations. As the focus of this study, the influence of CO2-O2 combustion environment on char reactivity and particularly carbon in ash has been investigated. It has been found that the effect of C-CO2 and C-H2O reactions on overall char reactivity cannot be disregarded. In addition, in this study, it is suggested that using the Langmuir-Hinshelwood mechanism can provide a more accurate prediction for the effect of gasification reactions on unburnt carbon and char reactivity. The accuracy of the CFD modeling has been investigated using experimental data from a one MWth combustion test facility. In order to improve the validity of the CFD code for design purposes, further modeling improvements for accurate predictions are addressed.

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.

Simulation of Circulating Fluidized Bed (CFB) Boiler Oxygen-Enriched Combustion

2012 ◽  
Vol 614-615 ◽  
pp. 139-142
Author(s):  
Yuan Ping Xu ◽  
Hua Zhou ◽  
Qing Yin Jiang
Keyword(s):  
Oxygen Content ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Combustion Efficiency ◽  
Configuration Software ◽  
Combustion Model ◽  
Cfb Boiler ◽  
Industrial Data ◽  
Real Process ◽  
The Relationship

In this paper, we focus on the relationship between oxygen-enriched combustion efficiency and oxygen content of primary air under N2 /O2 atmosphere combustion on CFB boiler. Firstly, an entirely possible of CFB boiler oxygen-enriched combustion model was proposed. Secondly, a platform was built for simulation of CFB combustion process on XD-APC configuration software. Finally, industrial simulation with industrial data was going on to prove the platform was reasonable. The simulation results were consistent of industrial data. It shows the simulation platform reliability, and the model accuracy. On this basis, coal combustion efficiency was simulated. It shows that the combustion efficiency increases following by oxygen content increasing. It’s economic for real process when oxygen content chooses from 25% to 30%.

Sign in / Sign up

Export Citation Format

Share Document