Experimental and numerical study on combustion of baled biomass in cigar burners and effects of flue gas re-circulation

The paper presents results of experimental and numerical investigation addressing combustion of baled agricultural biomass in a 50 kW experimental furnace equipped with cigar burners. Experiments performed included measurements of all parameters deemed important for mass and energy balance, as well as parameters defining quality of the combustion process. Experimental results were compared with results of numerical simulations performed with previously developed CFD model. The model takes into account complex thermo mechanical combustion processes occurring in a porous layer of biomass bales and the surrounding fluid. The combustion process and the corresponding model were deemed stationary. Comparison of experimental and numerical results obtained through research presented in this paper showed satisfactory correspondence, leading to the conclusion that the model developed could be used for analysis of different effects associated with variations in process parameters and/or structural modifications in industrial biomass facilities. Mathematical model developed was also utilized to examine the impact of flue gas recirculation on maximum temperatures in the combustion chamber. Gas recirculation was found to have positive effect on the reduction of maximum temperature in the combustion chamber, as well as on the reduction of maximum temperature zone in the chamber. The conclusions made provided valuable inputs towards prevention of biomass ash sintering, which occurs at higher temperatures and negatively affects biomass combustion process.

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Flue Gas Recirculation in a Gas Turbine: Impact on Performance and Operational Behavior

Volume 4: Cycle Innovations; Fans and Blowers; Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Oil and Gas Applications ◽

10.1115/gt2011-45608 ◽

2011 ◽

Cited By ~ 2

Author(s):

Frank Sander ◽

Richard Carroni ◽

Stefan Rofka ◽

Eribert Benz

Keyword(s):

Power Plant ◽

Co2 Capture ◽

Flue Gas ◽

Power Plants ◽

Combustion Process ◽

Combined Cycle ◽

Flue Gas Recirculation ◽

Overall Performance ◽

Gas Recirculation ◽

The Impact

The rigorous reduction of greenhouse gas emissions in the upcoming decades is only achievable with contribution from the following strategies: production efficiency, demand reduction of energy and carbon dioxide (CO2) capture from fossil fueled power plants. Since fossil fueled power plants contribute largely to the overall global greenhouse gas emissions (> 25% [1]), it is worthwhile to capture and store the produced CO2 from those power generation processes. For natural-gas-fired power plants, post-combustion CO2 capture is the most mature technology for low emissions power plants. The capture of CO2 is achieved by chemical absorption of CO2 from the exhaust gas of the power plant. Compared to coal fired power plants, an advantage of applying CO2 capture to a natural-gas-fired combined cycle power plant (CCPP) is that the reference cycle (without CO2 capture) achieves a high net efficiency. This far outweighs the drawback of the lower CO2 concentration in the exhaust. Flue Gas Recirculation (FGR) means that flue gas after the HRSG is partially cooled down and then fed back to the GT intake. In this context FGR is beneficial because the concentration of CO2 can be significantly increased, the volumetric flow to the CO2 capture unit will be reduced, and the overall performance of the CCPP with CO2 capture is increased. In this work the impact of FGR on both the Gas Turbine (GT) and the Combined Cycle Power Plant (CCPP) is investigated and analyzed. In addition, the impact of FGR for a CCPP with and without CO2 capture is investigated. The fraction of flue gas that is recirculated back to the GT, need further to be cooled, before it is mixed with ambient air. Sensitivity studies on flue gas recirculation ratio and temperature are conducted. Both parameters affect the GT with respect to change in composition of working fluid, the relative humidity at the compressor inlet, and the impact on overall performance on both GT and CCPP. The conditions at the inlet of the compressor also determine how the GT and water/steam cycle are impacted separately due to FGR. For the combustion system the air/fuel-ratio (AFR) is an important parameter to show the impact of FGR on the combustion process. The AFR indicates how close the combustion process operates to stoichiometric (or technical) limit for complete combustion. The lower the AFR, the closer operates the combustion process to the stoichiometric limit. Furthermore, the impact on existing operational limitations and the operational behavior in general are investigated and discussed in context of an operation concept for a GT with FGR.

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Calorimetric determination of the effect of additives on cement hydration process

Chemical Papers ◽

10.2478/s11696-012-0256-x ◽

2013 ◽

Vol 67 (2) ◽

Cited By ~ 16

Author(s):

Pavel Šiler ◽

Josef Krátký ◽

Iva Kolářová ◽

Jaromír Havlica ◽

Jiří Brandštetr

Keyword(s):

Portland Cement ◽

Silica Fume ◽

Maximum Temperature ◽

Granulated Blast Furnace Slag ◽

Mineral Components ◽

Maximum Temperatures ◽

The Impact ◽

Furnace Slag ◽

Calorimetric Determination

AbstractPossibilities of a multicell isoperibolic-semiadiabatic calorimeter application for the measurement of hydration heat and maximum temperature reached in mixtures of various compositions during their setting and early stages of hardening are presented. Measurements were aimed to determine the impact of selected components’ content on the course of ordinary Portland cement (OPC) hydration. The following components were selected for the determination of the hydration behaviour in mixtures: very finely ground granulated blast furnace slag (GBFS), silica fume (microsilica, SF), finely ground quartz sand (FGQ), and calcined bauxite (CB). A commercial polycarboxylate type superplasticizer was also added to the selected mixtures. All maximum temperatures measured for selected mineral components were lower than that reached for cement. The maximum temperature increased with the decreasing amount of components in the mixture for all components except for silica fume. For all components, except for CB, the values of total released heat were higher than those for pure Portland cement samples.

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The Impact of Predried Lignite Cofiring With Hard Coal in an Industrial Scale Pulverized Coal Fired Boiler

Journal of Energy Resources Technology ◽

10.1115/1.4039907 ◽

2018 ◽

Vol 140 (6) ◽

Cited By ~ 5

Author(s):

Halina Pawlak-Kruczek ◽

Robert Lewtak ◽

Zbigniew Plutecki ◽

Marcin Baranowski ◽

Michal Ostrycharczyk ◽

...

Keyword(s):

Combustion Chamber ◽

Bituminous Coal ◽

Cfd Simulation ◽

Numerical Study ◽

Fluid Dynamic ◽

Industrial Scale ◽

Hard Coal ◽

Cfd Simulations ◽

Reference Case ◽

The Impact

The paper presents the experimental and numerical study on the behavior and performance of an industrial scale boiler during combustion of pulverized bituminous coal with various shares of predried lignite. The experimental measurements were carried out on a boiler WP120 located in CHP, Opole, Poland. Tests on the boiler were performed during low load operation and the lignite share reached over to 36% by mass. The predried lignite, kept in dedicated separate bunkers, was mixed with bituminous coal just before the coal mills. Computational fluid dynamic (CFD) simulation of a cofiring scenario of lignite with hard coal was also performed. Site measurements have proven that cofiring of a predried lignite is not detrimental to the boiler in terms of its overall efficiency, when compared with a corresponding reference case, with 100% of hard coal. Experiments demonstrated an improvement in the grindability that can be achieved during co-milling of lignite and hard coal in the same mill, for both wet and dry lignite. Moreover, performed tests delivered empirical evidence of the potential of lignite to decrease NOx emissions during cofiring, for both wet and dry lignite. Results of efficiency calculations and temperature measurements in the combustion chamber confirmed the need to predry lignite before cofiring. Performed measurements of temperature distribution in the combustion chamber confirmed trend that could be seen in the results of CFD. CFD simulations were performed for predried lignite and demonstrated flow patterns in the combustion chamber of the boiler, which could prove useful in case of any further improvements in the firing system. CFD simulations reached satisfactory agreement with the site measurements in terms of the prediction of emissions.

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Verification of surface minimum, mean, and maximum temperature forecasts in Calabria for summer 2008

Natural Hazards and Earth System Science ◽

10.5194/nhess-11-487-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 487-500 ◽

Cited By ~ 11

Author(s):

S. Federico

Keyword(s):

Forecast Error ◽

Background Field ◽

Horizontal Resolution ◽

Atmospheric Modeling ◽

Forecast Skill ◽

Maximum Temperature ◽

Model Forecast ◽

Maximum Temperatures ◽

Analysis Error ◽

The Impact

Abstract. Since 2005, one-hour temperature forecasts for the Calabria region (southern Italy), modelled by the Regional Atmospheric Modeling System (RAMS), have been issued by CRATI/ISAC-CNR (Consortium for Research and Application of Innovative Technologies/Institute for Atmospheric and Climate Sciences of the National Research Council) and are available online at http://meteo.crati.it/previsioni.html (every six hours). Beginning in June 2008, the horizontal resolution was enhanced to 2.5 km. In the present paper, forecast skill and accuracy are evaluated out to four days for the 2008 summer season (from 6 June to 30 September, 112 runs). For this purpose, gridded high horizontal resolution forecasts of minimum, mean, and maximum temperatures are evaluated against gridded analyses at the same horizontal resolution (2.5 km). Gridded analysis is based on Optimal Interpolation (OI) and uses the RAMS first-day temperature forecast as the background field. Observations from 87 thermometers are used in the analysis system. The analysis error is introduced to quantify the effect of using the RAMS first-day forecast as the background field in the OI analyses and to define the forecast error unambiguously, while spatial interpolation (SI) analysis is considered to quantify the statistics' sensitivity to the verifying analysis and to show the quality of the OI analyses for different background fields. Two case studies, the first one with a low (less than the 10th percentile) root mean square error (RMSE) in the OI analysis, the second with the largest RMSE of the whole period in the OI analysis, are discussed to show the forecast performance under two different conditions. Cumulative statistics are used to quantify forecast errors out to four days. Results show that maximum temperature has the largest RMSE, while minimum and mean temperature errors are similar. For the period considered, the OI analysis RMSEs for minimum, mean, and maximum temperatures vary from 1.8, 1.6, and 2.0 °C, respectively, for the first-day forecast, to 2.0, 1.9, and 2.6 °C, respectively, for the fourth-day forecast. Cumulative statistics are computed using both SI and OI analysis as reference. Although SI statistics likely overestimate the forecast error because they ignore the observational error, the study shows that the difference between OI and SI statistics is less than the analysis error. The forecast skill is compared with that of the persistence forecast. The Anomaly Correlation Coefficient (ACC) shows that the model forecast is useful for all days and parameters considered here, and it is able to capture day-to-day weather variability. The model forecast issued for the fourth day is still better than the first-day forecast of a 24-h persistence forecast, at least for mean and maximum temperature. The impact of using the RAMS first-day forecast as the background field in the OI analysis is quantified by comparing statistics computed with OI and SI analyses. Minimum temperature is more sensitive to the change in the analysis dataset as a consequence of its larger representative error.

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Mathematical modeling of a swirling jet in applications to low-emission combustion of low-grade fuels

Zhurnal Srednevolzhskogo Matematicheskogo Obshchestva ◽

10.15507/2079-6900.23.202103.308-317 ◽

2021 ◽

Vol 23 (3) ◽

pp. 308-317

Author(s):

Usama J. Mizher ◽

Peter A. Velmisov

Keyword(s):

Carbon Dioxide ◽

Natural Gas ◽

Combustion Chamber ◽

Negative Impact ◽

Numerical Study ◽

Combustion Process ◽

Theoretical Data ◽

Modern Society ◽

Low Grade ◽

Modelling the Effect of External Flue Gas Recirculation on NOx and CO Emissions in a Premixed Gas Turbine Combustor With Chemical Reactor Networks

Volume 4B: Combustion, Fuels, and Emissions ◽

10.1115/gt2018-76548 ◽

2018 ◽

Cited By ~ 1

Author(s):

V. Prakash ◽

J. Steimes ◽

D. J. E. M. Roekaerts ◽

S. A. Klein

Keyword(s):

Gas Turbine ◽

Flue Gas ◽

Recirculation Zone ◽

Chemical Reactor ◽

Inlet Temperature ◽

Part Load ◽

Flue Gas Recirculation ◽

Reactor Networks ◽

Gas Recirculation ◽

The Impact

The increasing amount of renewable energy and emission norms challenge gas turbine power plants to operate at part-load with high efficiency, while reducing NOx and CO emissions. A novel solution to this dilemma is external Flue Gas Recirculation (FGR), in which flue gases are recirculated to the gas turbine inlet, increasing compressor inlet temperature and enabling higher part load efficiencies. FGR also alters the oxidizer composition, potentially leading to reduced NOx levels. This paper presents a kinetic model using chemical reactor networks in a lean premixed combustor to study the impact of FGR on emissions. The flame zone is split in two perfectly stirred reactors modelling the flame front and the recirculation zone. The flame reactor is determined based on a chemical time scale approach, accounting for different reaction kinetics due to FGR oxidizers. The recirculation zone is determined through empirical correlations. It is followed by a plug flow reactor. This method requires less details of the flow field, has been validated with literature data and is generally applicable for modelling premixed flames. Results show that due to less O2 concentration, NOx formation is inhibited down to 10–40% and CO levels are escalated up to 50%, for identical flame temperatures. Increasing combustor pressure leads to a rise in NOx due to thermal effects beyond 1800 K, and a drop in CO levels, due to the reduced chemical dissociation of CO2. Wet FGR reduces NOx by 5–10% and increases CO by 10–20%.

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Evaluating the Potential for Combustion of Biofuels in Grate Furnaces

Energies ◽

10.3390/en13081951 ◽

2020 ◽

Vol 13 (8) ◽

pp. 1951 ◽

Cited By ~ 1

Author(s):

Małgorzata Wzorek

Keyword(s):

Sewage Sludge ◽

Combustion Process ◽

Pollutant Emissions ◽

Biomass Combustion ◽

Municipal Sewage Sludge ◽

Hard Coal ◽

Meat And Bone Meal ◽

Bone Meal ◽

Coal Slime ◽

The Impact

The paper assesses the impact of combustion of biofuels produced based on municipal sewage sludge in stoker-fired boilers on the amount of pollutant emissions and examines the tendency of ash deposition of biofuels formed during the combustion process. The combustion tests were performed in a laboratory system enabling simulation of a combustion process present in stoker-fired boilers. The study was conducted for three types of biofuels; i.e., fuel from sewage sludge and coal slime (PBS fuel), sewage sludge and meat and bone meal (PBM fuel) and fuel based on sewage sludge and sawdust (PBT) with particle size of 35 mm and 15 mm. This paper describes and compares the combustion process of biofuels with different granulation and composition and presents the results of changes in emission values of NOx, SO2, CO, and CO2. The emission results were compared with the corresponding results obtained during combustion of hard coal. The results showed that biofuels with lower particle sizes were ignited faster and the shortest ignition time is achieved for fuel based on sewage sludge and coal slime-PBS fuel. Also, the highest NO and SO2 emissions were obtained for PBS fuel. During the combustion of fuel based on sewage sludge and meat and bone meal (PBM), on the other hand, the highest CO2 emissions were observed for both granulations. Biofuels from sludge show a combustion process that is different compared to the one for hard coal. The problems of ash fouling, slagging, and deposition during biofuels combustion were also identified. The tendency for ash slagging and fouling is observed, especially for fuel from sewage sludge and meat and bone meal (PBM) and fuel based on sewage sludge and sawdust (PBT) ashes which consist of meat and bone meal and sawdust which is typical for biomass combustion.

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The Partition Period of Thermodynamic Calculation and the Numerical Simulation for Lignite Blended Supercritical Boiler

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1030-1032.648 ◽

2014 ◽

Vol 1030-1032 ◽

pp. 648-652

Author(s):

Cai Ying Ban ◽

Xu Ao Lu ◽

Jian Meng Yang ◽

Xu Ran ◽

Feng Ying Liang

Keyword(s):

Numerical Simulation ◽

Flue Gas ◽

Thermodynamic Calculation ◽

Heat Load ◽

Combustion Process ◽

Heating Surface ◽

Gas Temperature ◽

Boiler Furnace ◽

Geometry Model ◽

The Impact

The purpose of this paper is to study the impact of furnace temperature and load after blending in lignite, based on CFD software FLUENT-6.3,this paper choose the appropriate geometry model and the physical and mathematical models, and numerical simulation of the different conditions 600MW supercritical once-through boiler blending lignite furnace combustion process is curried out. And through a 600MW supercritical coal-fired boiler furnace lignite blended performed sections thermodynamic calculation under different conditions, worked out the furnace flue gas temperature, CO, CO2concentration distribute trend and radiant heat each section surface heat load conditions. The specific amount were blended with 5%, 10%, 15%, 20% were not dried lignite and dried lignite 20% after five conditions. And obtained a conclusion is the temperature and radiation heating surface flue gas heat load in the overall trend under the various conditions.

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Gas Combustion Efficiency Enhancement: Application Study of Intense Elestrostatic Field

Latvian Journal of Physics and Technical Sciences ◽

10.2478/lpts-2019-0021 ◽

2019 ◽

Vol 56 (4) ◽

pp. 3-16

Author(s):

O. Krickis ◽

N. Zeltins

Keyword(s):

Electrostatic Field ◽

Flue Gas ◽

Combustion Process ◽

Field Application ◽

Process Efficiency ◽

Simultaneous Increase ◽

Efficiency Enhancement ◽

Gas Temperature ◽

Gas Combustion ◽

The Impact

Abstract A number of international, European Union and Latvian legislative acts have been developed, which regulate the efficiency of gas combustion plants and greenhouse gas emissions in the atmosphere. These legislative acts require the development of new scientifically efficient methods for gas optimal combustion with a minor impact on the environment. In order to achieve such a goal, different methods can be used, but the most efficient is an intensive electrostatic field application to control combustion and harmful emission formation in premixed flames. In the framework of the current study, the authors developed a hybrid burner, which allowed generating an intensive electrostatic field with intensity of more than 1000 kV/m. The study also investigated the impact of such a field on the formation of harmful emissions, including CO2 and flue gas temperature. The empirical results showed that an intensive DC electrostatic field generated inside of the burner had an impact on the flame shape, CO2, NOx emissions and flue gas temperature. In its turn, by applying an intensive pulsating electrostatic field (multivariable experiment) it was possible to achieve the reduction in NOx, CO emissions with a simultaneous increase in flue gas temperature, which was related to combustion process efficiency enhancement.

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Assessment of the Impact of Modification of Calcium Sorbents and the Possibility of Their Use in Desulfurization for Oxy-Fuel Combustion Process

Minerals ◽

10.3390/min11111284 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1284

Author(s):

Michał Wichliński ◽

Renata Włodarczyk

Keyword(s):

Flue Gas ◽

Mercury Porosimetry ◽

Combustion Process ◽

Flue Gas Desulfurization ◽

Sorption Coefficient ◽

Lithium Compounds ◽

Process Modification ◽

The Absolute ◽

Reactivity Coefficient ◽

The Impact

The paper describes the possibilities of simple and effective modification of calcium sorbents used for flue gas desulfurization with a size between of 125–250 µm. The additives to the sorbents in the amount of 0.5% and 1.0% were inorganic sodium and lithium compounds. The research on the reactivity of sorbents was analyzed in the process of simultaneous calcination and sulfation at the temperature of 850 °C. The type of Na+ or Li+ cations and the inorganic salt anions have an influence on the modification of calcium sorbents in order to improve the efficiency of the calcination and sulfation process. Modification of calcium sorbents by adding inorganic sodium and lithium compounds, regardless of the amount, changes the reactivity coefficient RI [mol/mol] and the absolute sorption coefficient CI [g S/kg sorbent]. In the case of inorganic sodium salt (Additive 1), regardless of the amount of modifier added, there was a visible improvement in the reactivity of the sorbent: 1.0% of the additive caused an increase in the RI coefficient in relation to the raw sorbent by over 14%, and in the case of the CI coefficient by over 24%. Additional research was the analysis of the limestone behavior mechanism during the simultaneous calcination and sulfation (SCS) process under conditions of elevated temperature and with variable CO2 and O2 contents in the flue gas. The behavior of sorbents with a size distribution of 125–250 µm was assessed on the basis of the change in mass of the samples by determining the reactivity coefficient RI, [mol/mol] and the absolute sorption coefficient CI, [g S/kg sorbent]. Using the mercury porosimetry technique, the change in sorbent porosity in the subsequent stages of the simultaneous calcination and sulfation process was investigated. The process was carried out in the temperature range corresponding to the oxy-combustion (i.e., from 850 °C to 1000 °C).

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