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.

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.

Wet Gas Impeller Test Facility

2010 ◽  
Author(s):  
Trond G. Gru¨ner ◽  
Lars E. Bakken
Keyword(s):  
Oil And Gas ◽  
Fluid Dynamic ◽  
Open Loop ◽  
Gas Production ◽  
Test Facility ◽  
Atmospheric Conditions ◽  
Oil And Gas Production ◽  
Wet Gas ◽  
Inlet Conditions ◽  
The Impact

The development of wet gas compressors will enable increased oil and gas production rates and enhanced profitable operation by subsea well-stream boosting. A more fundamental knowledge of the impact of liquid is essential with regard to the understanding of thermodynamic and fluid dynamic compressor behavior. An open-loop impeller test facility was designed to investigate the wet gas performance, aerodynamic stability, and operation range. The facility was made adaptable for different impeller and diffuser geometries. In this paper, the wet gas test facility and experimental work concerning the impact of wet gas on a representative full-scale industrial impeller are presented. The centrifugal compressor performance was examined at high gas volume fractions and atmospheric inlet conditions. Air and water were used as experimental fluids. Dry and wet gas performance was experimentally verified and analyzed. The results were in accordance with previous test data and indicated a stringent influence of the liquid phase. Air/water tests at atmospheric conditions were capable of reproducing the general performance trend of hydrocarbon wet gas compressor tests at high pressure.

Simulations of the PC boiler equipped with complex swirling burners

2014 ◽  
Vol 24 (4) ◽  
pp. 845-860 ◽  
Author(s):  
Wojciech P. Adamczyk ◽  
Pawel Kozolub ◽  
Gabriel Węcel ◽  
Arkadiusz Ryfa
Keyword(s):  
Fluid Dynamic ◽  
Exchange Process ◽  
Combustion Process ◽  
Accurate Solution ◽  
Flue Gases ◽  
Discrete Phase Model ◽  
Complex Flow ◽  
Content Type ◽  
Combustion Technology ◽  
The Impact

Purpose – The purpose of this paper is to show possible approaches which can be used for modeling complex flow phenomena caused by swirl burners combined with simulating coal combustion process using air- and oxy-combustion technologies. Additionally, the response of exist boiler working parameter on changing the oxidizer composition from air to a mixture of the oxygen and recirculated flue gases is investigated. Moreover, the heat transfer in the superheaters section of the boiler was taken into account by modeling of the heat exchange process between continuum phase and three stages of the steam superheaters. Design/methodology/approach – An accurate solution of the flow field is required in order to predict combustion phenomena correctly for numerical simulations of the industrial pulverized coal (PC) boilers. Nevertheless, it is a very demanding task due to the complicated swirl burner construction and complex character of the flow. The presented simulations were performed using the discrete phase model for tracking particles and combustion phenomena in a dispersed phase, whereas the Eulerian approach was applied for the volatile combustion process modeling in a gaseous phase. Findings – Applying the air- to oxy-combustion technology the temperature in the combustion chamber, decreased for investigated oxidizer compositions. This was caused by the higher heat capacity of flue gases which also influences on the level of the heat flux at the boiler walls. Simulations shows that increasing the O2 concentration to 30 percent of volume base in the oxidizer mixture provided the similar combustion conditions as those for the conventional air firing. Moreover, the evaluated results give a good overview of differences between approaches used for complex swirl burners simulations. Practical implications – Nowadays, the numerical techniques such as computational fluid dynamic (CFD) can be seen as an useful engineering tool for design and processes optimization purposes. The application of the CFD gives a possibility to predict the combustion phenomena in a large industrial PC boiler and investigate the impact of changing the combustion technology from a conventional air firing to oxy-fuel combustion. Originality/value – This paper gives good overview on existing technique, approaches used for modeling PC boiler equipped with complex swirl burners. Additionally, the novelty of this work is application of the heat exchanger model for predicting heat loses in convective section of the boiler. This usually is not taken into account during simulations. The reader can also find basic concept of oxy-combustion technology, and their impact on boiler working conditions.

Prediction of Performance and Pollutant Emission From Bituminous and Sub-Bituminous Coals in Utility Boilers

2007 ◽  
Author(s):  
Roman Saveliev ◽  
Boris Chudnovsky ◽  
Ben-Zion Kogan ◽  
Efim Korytnyi ◽  
Miron Perelman ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Coal Combustion ◽  
Fluid Dynamic ◽  
Test Facility ◽  
Pollutant Emission ◽  
Model Parameters ◽  
Cfd Models ◽  
Utility Boilers ◽  
Series Of Experiments ◽  
Bituminous Coals

Computational Fluid Dynamic (CFD) models give good predictions of coal combustion in utility boilers if the coal combustion kinetic parameters are known. We developed a three-step methodology to provide reliable prediction of the behavior of a coal in a utility boiler: (1) Obtaining the combustion kinetic model parameters from a series of experiments in a test facility, CFD codes and optimization algorithm. (2) Validation of the combustion kinetic parameters by comparison of different experimental data with simulation results obtained by the set of combustion kinetic parameters. (3) The extracted kinetic parameters are then used for simulations of full-scale boilers using the same CFD code. Three to four bituminous and sub-bituminous coals with known behavior in Israel Electric Corporation (IEC) 550MW opposite-wall (3 coals) and 575MW tangential-fired (4 coals) boilers were used to show the capability of the method. An unfamiliar bituminous coal was then examined prior of its firing in the utility boilers and prediction of its combustion behavior in the two boilers was carried out. This methodology was used to examine a Venezuelan coal that was found to yield high LOI.

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>

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.

Multiphase CFD Model Development for a Rotating Centrifugal Separator

2012 ◽  
Author(s):  
Daniel DeMore ◽  
William Maier
Keyword(s):  
Separation Efficiency ◽  
Fluid Dynamic ◽  
Model Development ◽  
Modeling Method ◽  
Operating Conditions ◽  
Cfd Modeling ◽  
Separation Performance ◽  
Centrifugal Separator ◽  
Wide Range ◽  
The Impact

The present paper describes the development of a Computational Fluid Dynamic (CFD) modeling approach suitable for the analysis, design, and optimization of rotating centrifugal separator stage geometries. The Homogeneous Multiple Size Group (MUSIG) model implemented in the commercial code CFX V13.0 was utilized as a basis for the CFD modeling method. The model was developed through a series of studies to understand the impact of droplet size distribution, particle coalescence, rotor/stator interface treatment, and mesh resolution on the prediction of separation efficiency for a given rotating separator geometry. This model was then validated against the OEM’s extensive in-house experimental separation testing database. The resulting CFD modeling method is shown to adequately reproduce observed trends in separation performance over a wide range of operating conditions.

scholarly journals The impact of large mobile air purifiers on aerosol concentration in classrooms and the reduction of airborne transmission of SARS-CoV-2

2021 ◽  
Author(s):  
Finn F. Duill ◽  
Florian Schulz ◽  
Aman Jain ◽  
Leve Krieger ◽  
Berend van Wachem ◽  
...  
Keyword(s):  
Natural Ventilation ◽  
Particle Concentration ◽  
Substantial Reduction ◽  
Aerosol Concentration ◽  
Optimal Placement ◽  
Cfd Modeling ◽  
Risk Of Infection ◽  
Duration Of Stay ◽  
Increased Risk ◽  
The Impact

In the wake of the SARS-CoV-2 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools without pre-installed ventilation systems that are equipped with filters and/or operate with fresh air. Here, the aerosol concentration is reduced by natural ventilation. In this context, we are investigating the effect of large mobile air purifiers (AP) with HEPA filters on particle concentration and their suitability for classroom use in a primary school in Germany. The three tested APs differ significantly in their air outlet characteristics. Measurements of the number of particles, the particle size distribution, and the CO2 concentration were carried out in the classroom with students (April/May 2021) and with an aerosol generator without students. In this regard, the use of APs leads to a substantial reduction in aerosol particles. At the same time, the three APs are found to have differences in their particle decay rate, noise level, and flow velocity. In addition to the measurements, the effect of various influencing parameters on the potential inhaled particle dose was investigated using a calculation model. The parameters considered include the duration of stay, particle concentration in exhaled air, respiratory flow rate, virus lifetime, ventilation interval, ventilation efficiency, AP volumetric flow, as well as room size. Based on the resulting effect diagrams, significant recommendations can be derived for reducing the risk of infection from virus-laden aerosols. Finally, the measurements were compared to computational fluid dynamics (CFD) modeling, as such tools can aid the optimal placement and configuration of APs and can be used to study the effect of the spread of aerosols from a source in the classroom.

scholarly journals The Impact of Large Mobile Air Purifiers on Aerosol Concentration in Classrooms and the Reduction of Airborne Transmission of SARS-CoV-2

2021 ◽  
Vol 18 (21) ◽  
pp. 11523
Author(s):  
Finn F. Duill ◽  
Florian Schulz ◽  
Aman Jain ◽  
Leve Krieger ◽  
Berend van Wachem ◽  
...  
Keyword(s):  
Particle Size ◽  
Particle Concentration ◽  
Substantial Reduction ◽  
Aerosol Concentration ◽  
Optimal Placement ◽  
Cfd Modeling ◽  
Risk Of Infection ◽  
Duration Of Stay ◽  
Increased Risk ◽  
The Impact

In the wake of the COVID-19 pandemic, an increased risk of infection by virus-containing aerosols indoors is assumed. Especially in schools, the duration of stay is long and the number of people in the rooms is large, increasing the risk of infection. This problem particularly affects schools without pre-installed ventilation systems that are equipped with filters and/or operate with fresh air. Here, the aerosol concentration is reduced by natural ventilation. In this context, we are investigating the effect of large mobile air purifiers (AP) with HEPA filters on particle concentration and their suitability for classroom use in a primary school in Germany. The three tested APs differ significantly in their air outlet characteristics. Measurements of the number of particles, the particle size distribution, and the CO2 concentration were carried out in the classroom with students (April/May 2021) and with an aerosol generator without students. In this regard, the use of APs leads to a substantial reduction of aerosol particles in the considered particle size range of 0.178–17.78 µm. At the same time, the three APs are found to have differences in their particle decay rate, noise level, and flow velocity. In addition to the measurements, the effect of various influencing parameters on the potential inhaled particle dose was investigated using a calculation model. The parameters considered include the duration of stay, particle concentration in exhaled air, respiratory flow rate, virus lifetime, ventilation interval, ventilation efficiency, AP volumetric flow, as well as room size. Based on the resulting effect diagrams, significant recommendations can be derived for reducing the risk of infection from virus-laden aerosols. Finally, the measurements were compared to computational fluid dynamics (CFD) modeling, as such tools can aid the optimal placement and configuration of APs and can be used to study the effect of the spread of aerosols from a source in the classroom.

Computational Modeling of a 1MW Scale Combustor for a Direct Fired sCO2 Power Cycle

2018 ◽  
Author(s):  
Jacob Delimont ◽  
Nathan Andrews ◽  
Lalit Chordia
Keyword(s):  
Carbon Capture ◽  
Power Plants ◽  
Fossil Fuels ◽  
Combustion Process ◽  
Combined Cycle ◽  
Cfd Modeling ◽  
Inlet Temperature ◽  
Power Cycle ◽  
Natural Gas Combined Cycle ◽  
Cycle Efficiency

Direct fired oxy-fuel combustion provides a promising method for heat addition into a supercritical carbon dioxide (sCO2) power cycle. Using this method of thermal energy input into the cycle allows for potentially higher fuel to bus bar cycle efficiency. In addition, the nature of the sCO2 power cycle lends itself to easy and efficient capture of 99% of the CO2 generated in the combustion process. sCO2 power cycles typically operate at pressures above 200 bar, and due to the high degree of recuperation found in these cycles, have a very high combustor inlet temperature. Past works have explored combustor inlet temperatures high enough to be in the autoignition regime. The inlet temperatures which will be explored in this work will be limited to 700°C, which will allows for very different combustor geometry than that which has been studied in the past. While this combustor inlet temperature is lower than that previously studied, when combined with the extremely high pressure, this poses several unique and difficult design challenges. In order to explore these unique design conditions a reliable and robust CFD solution method was developed. This reliable CFD solution methodology enables rapid iteration on various geometries. This paper will explore the CFD modeling setup and the assumptions which were made in the absence of well experimental data in this combustor regime. Exploration of methodology to account for possible variations in chemical kinetics due to the lack of validated kinetic models in the current literature will also be discussed. The results from the CFD runs will be discussed and the combustor design, and next steps to complete a detailed combustor design will also be discussed. This work will enable future work in the development of oxy-fuel combustors for direct fired sCO2 power. This promising technology enables the use of fossil fuels with up to 99% carbon capture, while maintaining an overall cycle efficiency competitive with natural gas combined cycle power plants.

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