Combustion Characteristics of Ultrafine Coal Particles-Light Diesel Oil Mixtures in a Cylindrical Horizontal Furnace

2020 ◽  
Vol 143 (7) ◽  
Author(s):  
ELSaeed Saad ELSihy ◽  
M. M. Salama ◽  
M. A. Shahein ◽  
H. A. Moneib ◽  
M. K. Abd EL-Rahman
Keyword(s):  
Flame Temperature ◽  
Fuel Mixture ◽  
Combustion Characteristics ◽  
Slight Reduction ◽  
Percentage Increase ◽  
Gas Temperature ◽  
Flame Zone ◽  
Constant Input ◽  
Coal Particles ◽  
Loading Ratio

Abstract This work presents an experimental study that aims at investigating the effect of the loading ratio of coal in a coal-diesel fuel mixture on the combustion characteristics and exhaust emissions. Sub-bituminous coal from the El-Maghara coal mine is utilized. It is washed, dried, and grounded to particle sizing of ≤ 30 μm. The experiments are conducted inside a horizontal, segmented water-cooled cylindrical furnace fitted with a coaxial burner having a central air-assisted atomizer for oil-coal mixture admittance. All experiments are executed at constant input heat of 350 kW and air-to-fuel ratio of 15:1 while varying the percentage (mass basis: 5% and 10%) of coal in the fuel mixture. The measurements within the flame zone include mean gas temperatures, dry volumetric analyses of species (CO2, NOx, and O2) concentrations, and the accumulative heat transfer to the cooling jacket along the combustor. All measurements are compared regarding the pure oil flame. The results indicate that increasing the coal-loading ratio up to 5 wt% leads to a progressive increase in the accumulated heat transferred and the combustor overall efficiency from 40% to 58% within a percentage increase around 45%. In addition, there is a slight reduction in mean gas temperature within the flame zone when compared with the pure oil flame. The reduced flame temperature due to increasing the coal-loading ratio caused a decline in the volumetric concentrations of NOx from 100 ppm to 20 ppm as expected.

Studies on Coal Ignition and Combustion Characteristics

2017 ◽  
Author(s):  
Xue Chen ◽  
MingYan Gu ◽  
XianHui He ◽  
Dan Yan ◽  
Jimin Wang ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Coal Particle ◽  
Gas Flow ◽  
Ignition Time ◽  
Particle Diameter ◽  
Combustion Characteristics ◽  
Gas Temperature ◽  
Flow Temperature ◽  
Particle Ignition ◽  
Coal Particles

A 2-D numerical model of flow, heat transfer, and combustion of coal particles in a laminar gas flow at O2/CO2 atmosphere was developed based on the Eulerian-Lagrangian methodology. The gas-phase combustion was modeled using the GRI-Mech 3.0. The motion of coal particles was simulated using a trajectory model. The model was employed to study the coal ignition time, temperature and mass changes. The effects of particle diameter, the flow temperature and oxygen concentration on the ignition time and the combustion characteristics of coal particles were also investigated. The results obtained show that smaller size particle experiences a shorter ignition time with a higher coal temperature. A higher gas temperature leads to a shorter coal particle ignition time; increasing the flow temperature the difference in the ignition time of different sized coal particles decreases. The coal particle ignition time is decreased when the oxygen concentration is increased.

Differential Mass and Energy Balances in the Flame Zone From a Practical Fuel Injector in a Technology Combustor

1997 ◽  
Vol 119 (2) ◽  
pp. 352-361 ◽  
Author(s):  
D. L. Warren ◽  
P. O. Hedman
Keyword(s):  
Heat Release ◽  
Air Force ◽  
Flame Temperature ◽  
Fuel Injector ◽  
Gas Temperature ◽  
Flame Zone ◽  
Brigham Young University ◽  
Air Force Base ◽  
Energy Balances ◽  
Mass And Energy Balances

This paper presents further analysis of experimental results from an Air Force program conducted by researchers at Brigham Young University (BYU), Wright-Patterson Air Force Base (WPAFB), and Pratt and Whitney Aircraft Co. (P&W) (Hedman et al., 1994a, 1995). These earlier investigations of the combustion of propane in a practical burner installed in a technology combustor used: (1) digitized images from video and still film photographs to document observed flame behavior as fuel equivalence ratio was varied, (2) sets of LDA data to quantify the velocity flow fields existing in the burner, (3) CARS measurements of gas temperature to determine the temperature field in the combustion zone, and to evaluate the magnitude of peak temperature, and (4) two-dimensional PLIF images of OH radical concentrations to document the instantaneous location of the flame reaction zones. This study has used the in situ velocity and temperature measurements from the earlier study, suitably interpolated, to determine local mass and energy balances on differential volume elements throughout the flame zone. The differential mass balance was generally within about ±10 percent with some notable exceptions near regions of very high shear and mixing. The local differential energy balance has qualitatively identified the regions of the flame where the major heat release is occurring, and has provided quantitative values on the rate of energy release (up to −400 kJ/m3s). The velocity field data have also been used to determine Lagrangian pathlines through the flame zone. The local velocity and temperature along selected pathlines have allowed temperature timelines to be determined. The temperature generally achieves its peak value, often near the adiabatic flame temperature, within about 10 ms. These temperature timelines, along with the quantitative heat release data, may provide a basis for evaluating kinetic combustion models.

Large Eddy Simulation on the Effects of Coal Particles Size on Turbulent Combustion Characteristics and NOx Formation Inside a Corner-Fired Furnace

2020 ◽  
Vol 143 (8) ◽  
Author(s):  
Wenjing Sun ◽  
Wenqi Zhong ◽  
Jingzhou Zhang ◽  
Tarek Echekki
Keyword(s):  
Large Eddy Simulation ◽  
Coal Combustion ◽  
Flame Temperature ◽  
Particle Dispersion ◽  
Combustion Characteristics ◽  
Pulverized Coal ◽  
Nox Formation ◽  
Eddy Simulation ◽  
Coal Particles ◽  
Large Eddy

Abstract The effects of pulverized coal particles’ sizes on the coal combustion characteristics are numerically studied in a laboratory-scale tangentially fired furnace. The turbulent gas flow and the coal particle motion are solved by employing the large eddy simulation (LES) and the discrete phase model (DPM). The mixture fraction probability density function (MF-PDF) is coupled to simulate the non-premixed pulverized coal combustion. It is found that the coal combustion efficiency is positively affected by the dispersion of coal powders. The particle dispersion and the coal combustion are augmented by the intensive impingement caused by the corner-injected flow. Large coal particles, with their greater inertia, enhance particle agglomerations, which limit the combustion of volatile and char. Accordingly, the average flame temperature decreases with the growing particle sizes. Also, the O2 concentration increases slightly because of the incomplete coal combustion, and the CO2 concentration decreases gradually. In contrast, the CO concentration increases markedly in the furnace center due to the presence of a reducing atmosphere. The NO concentration exhibits an exponential decline with the increased particle size. A relatively stable combustion and a relatively low NOx formation are acquired inside such a corner-fired furnace when the particle Stokes number is a little greater than 1.

scholarly journals Differential Mass and Energy Balances in the Flame Zone From a Practical Fuel Injector in a Technology Combustor

1995 ◽  
Author(s):  
David L. Warren ◽  
Paul O. Hedman
Keyword(s):  
Heat Release ◽  
Air Force ◽  
Flame Temperature ◽  
Fuel Injector ◽  
Gas Temperature ◽  
Flame Zone ◽  
Brigham Young University ◽  
Air Force Base ◽  
Energy Balances ◽  
Mass And Energy Balances

This paper presents further analysis of experimental results from an Air Force program conducted by researchers at Brigham Young University (BYU) Wright-Patterson Air Force Base (WPAFB), and Pratt and Whitney Aircraft Co. (P&W) (Hedman, et al., 1994a and 1994b). These earlier investigations of the combustion of propane in a practical burner installed in a technology combustor used: 1) digitized images from video and still film photographs to document observed flame behavior as fuel equivalence ratio was varied, 2) sets of LDA data to quantify the velocity flow fields existing in the burner, 3) CARS measurements of gas temperature to determine the temperature field in the combustion zone, and to evaluate the magnitude of peak temperature, and 4) two-dimensional PLIF images of OH radical concentrations to document the instantaneous location of the flame reaction zones. This study has used the in situ velocity and temperature measurements from the earlier study, suitably interpolated, to determine local mass and energy balances on differential volume elements throughout the flame zone. The differential mass balance was generally within about ± 10% with some notable exceptions near regions of very high shear and mixing. The local differential energy balance has qualitatively identified the regions of the flame where the major heat release is occurring, and has provided quantitative values on the rate of energy release (up to −400 kJ/m3s). The velocity field data have also been used to determine Lagrangian pathlines through the flame zone. The local velocity and temperature along selected pathlines have allowed temperature timelines to be determined. The temperature generally achieves its peak value, often near the adiabatic flame temperature, within about 10 ms. These temperature timelines, along with the quantitative heat release data may provide a basis for evaluating kinetic combustion models.

Effect of Fuel Stage Proportion on Flame Position in an Internally-Staged Combustor

2020 ◽  
Author(s):  
Tiezheng Zhao ◽  
Xiao Liu ◽  
Hongtao Zheng ◽  
Zhihao Zhang ◽  
Jialong Yang ◽  
...  
Keyword(s):  
Turbulent Flame ◽  
Flame Temperature ◽  
Prediction Method ◽  
Combustion Characteristics ◽  
Turbulent Flame Speed ◽  
Pilot Fuel ◽  
High Temperature Area ◽  
Incomplete Reaction ◽  
Co Emission ◽  
Flame Position

Abstract To study the effect of fuel stage proportion on flame position and combustion characteristics of the internally-staged combustor, a detailed numerical investigation is performed in the present paper. The prediction method of flame position is established by analyzing the variations of the distribution of intermediate components and the turbulent flame speed. Meanwhile, the flame position is simulated to verify the accuracy of the prediction method. It is demonstrated that the flame position prediction model established in this paper can accurately predict the flame position under different fuel stage proportions. On this basis, special attention is paid to analyze the variation of velocity field, temperature field, distribution of intermediate components and emissions under different fuel stage proportions. As the proportion of pilot fuel stage increases slightly, the mass fraction of fuel at the combustor dome increases. In addition, the combustion characteristics change significantly with the increase in the proportion of pilot stage fuels. The flame moves downstream and the high temperature area increases as the proportion of pilot fuel increases. In particular, when the proportion of pilot stage reaches 3%, the highest flame temperature is generated due to the most concentrated reaction area, resulting in the largest emission of NOx. At the same time, due to the most complete reaction, the minimum CO emission is produced. When the proportion of pilot fuel stage reaches 1%, the NOx emission is the lowest, and the highest CO emission is generated due to the incomplete reaction.

Ultra-Low Emission Hydrogen/Syngas Combustion With a 1.3 MW Injector Using a Micro-Mixing Lean-Premix System

2011 ◽  
Author(s):  
Brian Hollon ◽  
Erlendur Steinthorsson ◽  
Adel Mansour ◽  
Vincent McDonell ◽  
Howard Lee
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Flame Temperature ◽  
Fuel Mixture ◽  
Full Scale ◽  
Operating Conditions ◽  
Nox Emissions ◽  
Fuel Injector ◽  
Nitrogen Dilution ◽  
Fuel Mixtures

This paper discusses the development and testing of a full-scale micro-mixing lean-premix injector for hydrogen and syngas fuels that demonstrated ultra-low emissions and stable operation without flashback for high-hydrogen fuels at representative full-scale operating conditions. The injector was fabricated using Macrolamination technology, which is a process by which injectors are manufactured from bonded layers. The injector utilizes sixteen micro-mixing cups for effective and rapid mixing of fuel and air in a compact package. The full scale injector is rated at 1.3 MWth when operating on natural gas at 12.4 bar (180 psi) combustor pressure. The injector operated without flash back on fuel mixtures ranging from 100% natural gas to 100% hydrogen and emissions were shown to be insensitive to operating pressure. Ultra-low NOx emissions of 3 ppm were achieved at a flame temperature of 1750 K (2690 °F) using a fuel mixture containing 50% hydrogen and 50% natural gas by volume with 40% nitrogen dilution added to the fuel stream. NOx emissions of 1.5 ppm were demonstrated at a flame temperature over 1680 K (2564 °F) using the same fuel mixture with only 10% nitrogen dilution, and NOx emissions of 3.5 ppm were demonstrated at a flame temperature of 1730 K (2650 °F) with only 10% carbon dioxide dilution. Finally, using 100% hydrogen with 30% carbon dioxide dilution, 3.6 ppm NOx emissions were demonstrated at a flame temperature over 1600 K (2420 °F). Superior operability was achieved with the injector operating at temperatures below 1470 K (2186 °F) on a fuel mixture containing 87% hydrogen and 13% natural gas. The tests validated the micro-mixing fuel injector technology and the injectors show great promise for use in future gas turbine engines operating on hydrogen, syngas or other fuel mixtures of various compositions.

Experimental Study of Natural Gas Fuel Temperature Influence on Radiation Enhancement and Emission

2010 ◽  
Author(s):  
S. Mohammad Javadi ◽  
Pourya Nikoueeyan ◽  
Mohammad Moghiman ◽  
M. Ebrahim Feyz
Keyword(s):  
Radiation Intensity ◽  
Flame Temperature ◽  
Photovoltaic Module ◽  
Exhaust Gas ◽  
Gas Temperature ◽  
Fuel Temperature ◽  
Flame Radiation ◽  
Exhaust Gases ◽  
No Formation ◽  
Exhaust Gas Temperature

The enhancement of the flame radiation in gas fueled burners not only improves the thermal efficiency, but also can suppress the rate of NO emission due to reducing the flame temperature. In this experimental investigation, the effect of inlet gas temperature on the flame radiation intensity and the rate of NO formation are studied. To serve this aim, with increasing the temperature of inlet methane to the burner up to 310°C, the variations of CO and NO level in exhaust gases and also the exhaust gas temperature are recorded by gas analyzer device. In each case, the flame radiation intensity was also measured by a photovoltaic module. The results revealed that by increasing the inlet gas temperature up to 250°C, the NO concentration and the exhaust gases temperature are raising. But when the inlet gas temperature exceeds from 250°C and reaches to 310°C, the flame luminosity gradually increases which results in 70 percent growth in flame radiation and 10 percent drop in exhaust gas temperature. The results of the preheating of inlet air also show the same behavior.

Calculated flame temperature (CFT) modeling of fuel mixture lower flammability limits

2010 ◽  
Vol 174 (1-3) ◽  
pp. 416-423 ◽  
Author(s):  
Fuman Zhao ◽  
William J. Rogers ◽  
M. Sam Mannan
Keyword(s):  
Flame Temperature ◽  
Fuel Mixture ◽  
Flammability Limits
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