scholarly journals Effects of Pressure and Coal Rank on the Oxy-Fuel Combustion of Pulverized Coal

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 265
Author(s):  
Dingyi Qin ◽  
Qianyun Chen ◽  
Jing Li ◽  
Zhaohui Liu
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Bituminous Coal ◽  
Ignition Delay Time ◽  
Reaction System ◽  
Fuel Combustion ◽  
Release Time ◽  
Anthracite Coal ◽  
Combustion Technology

Pressurized oxy-fuel combustion technology is the second generation of oxy-fuel combustion technology and has low energy consumption and low cost. In this research, a visual pressurized flat-flame reaction system was designed. A particle-tracking image pyrometer (PTIP) system based on a high-speed camera and an SLR camera was proposed. Combining the experimental system and data-processing method developed, the ignition and combustion characteristics of a single coal particle between 69 and 133 μm in size were investigated. The results indicated that at atmospheric pressure, the ignition delay time of ShanXi (SX) anthracite coal was longer than that of ShenHua (SH) bituminous coal, while that of PRB sub-bituminous coal was the shortest. As the pressure rose, the ignition delay time of the PRB sub-bituminous coal and SX anthracite coal showed a continuous increasing trend, while the ignition delay time of SH bituminous coal showed a trend of first increasing and then decreasing. Moreover, pressure also affects the pyrolysis process of coal. As the pressure increases, it became more difficult to release the volatiles produced by coal pyrolysis, which reduced the release rate of volatiles during the ignition stage, and prolonged the release time and burning duration time of volatiles.

scholarly journals Aging of mechanically activated wood: Effect on the burning ability

2021 ◽  
pp. 145-145
Author(s):  
Anna Matveeva ◽  
Andrey Komarovskikh ◽  
Artem Kuznetsov ◽  
Pavel Plyusnin ◽  
Vladimir Bukhtoyarov ◽  
...  
Keyword(s):  
Time Delay ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Combustion Efficiency ◽  
Fuel Production ◽  
Pine Sawdust ◽  
Powder Production ◽  
Combustion Technology

One of the aspects for optimizing the powdered biofuel combustion technology is to ensure proper relationship between powder production and its delivery into the reactor. This paper focuses on the effect of a time delay between production and use of powdered fuel on its combustion efficiency using pine sawdust as an example. It was established that the ignition delay time increases with an increasing delay between powdered fuel production and use (i.e., the effect of sample aging takes place). A correlation between the ignition delay time, the amount of lignin radicals, and the sample's ability to release volatile combustible matter is demonstrated.

Experimental Study and Modeling of Autoignition of Natural Gas/Air-Mixtures Under Gas Turbine Relevant Conditions

2005 ◽  
Author(s):  
Andreas Koch ◽  
Clemens Naumann ◽  
Wolfgang Meier ◽  
Manfred Aigner
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Ignition Delay Time ◽  
Evaluation Procedure ◽  
Ignition Process ◽  
Ignition Delay Times ◽  
Delay Times

The objective of this work was the improvement of methods for predicting autoignition in turbulent flows of different natural gas mixtures and air. Measurements were performed in a mixing duct where fuel was laterally injected into a turbulent flow of preheated and pressurized air. To study the influence of higher order hydrocarbons on autoignition, natural gas was mixed with propane up to 20% by volume at pressures up to 15 bar. During a measurement cycle, the air temperature was increased until autoignition occurred. The ignition process was observed by high-speed imaging of the flame chemiluminescence. In order to attribute a residence time (ignition delay time) to the locations where autoignition was detected the flow field and its turbulent fluctuations were simulated by numerical codes. These residence times were compared to calculated ignition delay times using detailed chemical simulations. The measurement system and data evaluation procedure are described and preliminary results are presented. An increase in pressure and in fraction of propane in the natural gas both reduced the ignition delay time. The measured ignition delay times were systematically longer than the predicted ones for temperatures above 950 K. The results are important for the design process of gas turbine combustors and the studies also demonstrate a procedure for the validation of design tools under relevant conditions.

scholarly journals Effect of Cu(NO3)2 and Cu(CH3COO)2 Activating Additives on Combustion Characteristics of Anthracite and Its Semi-Coke

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5926
Author(s):  
Kirill Larionov ◽  
Konstantin Slyusarskiy ◽  
Svyatoslav Tsibulskiy ◽  
Anton Tolokolnikov ◽  
Ilya Mishakov ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Ignition Delay Time ◽  
Early Stage ◽  
Copper Acetate ◽  
Gas Analysis ◽  
Copper Salts ◽  
Activating Additives ◽  
On Line

The process of anthracite and its semi-coke combustion in the presence of 5 wt.% (in terms of dry salt) additives of copper salts Cu(NO3)2 and Cu(CH3COO)2 was studied. The activating additives were introduced by an incipient wetness procedure. The ignition and combustion parameters for coal samples were examined in the combustion chamber at the heating medium temperatures (Tg) of 600–800 °C. The composition of the gaseous combustion products was controlled using an on-line gas analyzer. The fuel modification with copper salts was found to reduce the ignition delay time on average, along with a drop in the minimum ignition temperature Tmin by 138–277 °C. With an increase in Tg temperature, a significant reduction in the ignition delay time for the anthracite and semi-coke samples (by a factor of 6.7) was observed. The maximum difference in the ignition delay time between the original and modified samples of anthracite (ΔTi = 5.5 s) and semi-coke (ΔTi = 5.4 s) was recorded at a Tg temperature of 600 °C in the case of Cu(CH3COO)2. The emergence of micro-explosions was detected at an early stage of combustion via high-speed video imaging for samples modified by copper acetate. According to the on-line gas analysis data, the addition of copper salts permits one to reduce the volume of CO formed by 40% on average, providing complete oxidation of the fuel to CO2. It was shown that the introduction of additives promoted the reduction in the NOx emissions during the combustion of the anthracite and semi-coke samples.

scholarly journals High-Speed Imaging and Measurements of Ignition Delay Times in Oxy-Syngas Mixtures With High CO2 Dilution in a Shock Tube

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Samuel Barak ◽  
Owen Pryor ◽  
Joseph Lopez ◽  
Erik Ninnemann ◽  
Subith Vasu ◽  
...  
Keyword(s):  
Shock Tube ◽  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Ignition Delay Time ◽  
High Speed Imaging ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Syngas Combustion ◽  
End Wall

In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2 cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% to 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing the equivalence ratios (ϕ), between 0.33, 0.5, and 1.0 as well as changing the fuel ratio (θ), hydrogen to carbon monoxide, from 0.25, 1.0, and 4.0. The study was performed at 1.61–1.77 atm and a temperature range of 1006–1162 K. The high-speed imaging was performed through a quartz end wall with a Phantom V710 camera operated at 67,065 frames per second. From the experiments, when increasing the equivalence ratio, it resulted in a longer ignition delay time. In addition, when increasing the fuel ratio, a lower ignition delay time was observed. These trends are generally expected with this combustion reaction system. The high-speed imaging showed nonhomogeneous combustion in the system; however, most of the light emissions were outside the visible light range where the camera is designed for. The results were compared to predictions of two combustion chemical kinetic mechanisms: GRI v3.0 and AramcoMech v2.0 mechanisms. In general, both mechanisms did not accurately predict the experimental data. The results showed that current models are inaccurate in predicting CO2 diluted environments for syngas combustion.

scholarly journals Chemical Kinetic Study on Dual-Fuel Combustion: The Ignition Properties of n-Dodecane/Methane Mixture

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Weijian Zhou ◽  
Song Zhou ◽  
Hongyuan Xi ◽  
Majed Shreka ◽  
Zhao Zhang
Keyword(s):  
Free Radicals ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Reaction System ◽  
Dual Fuel ◽  
Ignition Process ◽  
Mixing Ratio ◽  
Mixture Ratio ◽  
Methane Mixture

The natural gas (NG)/diesel dual-fuel engine has attracted extensive attention in recent years, and the influence of ignition delay on the engine is very important. Therefore, the research on the ignition delay of NG/diesel dual fuel is of great significance. In this work, a simplified n-dodecane mechanism was used to study the effect of methane mixture ratio on the n-dodecane ignition process. The results showed that the ignition delay time increased with the increase of methane content by changing the mixing ratio of methane and n-dodecane. However, the effect of methane on the ignition delay time gradually decreases when the content of the n-dodecane mixing ratio is greater than 50%. It was also found that with the increase of n-dodecane content, the reduction degree of the ignition delay time of the whole reaction system decreased and the negative temperature coefficient (NTC) behavior increased. Moreover, when the initial pressure increased from 20 bar to 60 bar, the thermal effect of methane also increases from 7.03% to 9.55%. The relationship between ignition characteristics of methane-n-dodecane and temperature was studied by changing the initial temperature. Furthermore, the evolution of species in the ignition process of the whole reaction system was analyzed, and the decomposition of n-dodecane first occurs in the reaction n-C12H26 + O2 = R + HO2 to form R and free radicals; however, the reaction CH4 + OH = CH3 + H2O dominates with the increase of the methane mixing ratio and inhibits the ignition process. Through the analysis of reaction paths, sensitivity, and rates of production and consumption of methane/n-dodecane, it was explained how n-dodecane accelerates methane ignition through the rapidly formed free radicals.

High-Speed Imaging and Measurements of Ignition Delay Times in Oxy-Syngas Mixtures With High CO2 Dilution in a Shock Tube

2017 ◽  
Author(s):  
Samuel Barak ◽  
Owen Pryor ◽  
Joseph Lopez ◽  
Erik Ninnemann ◽  
Subith Vasu ◽  
...  
Keyword(s):  
Shock Tube ◽  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Ignition Delay Time ◽  
High Speed Imaging ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Syngas Combustion ◽  
End Wall

In this study, syngas combustion was investigated behind reflected shock waves in order to gain insight into the behavior of ignition delay times and effects of the CO2 dilution. Pressure and light emissions time-histories measurements were taken at a 2cm axial location away from the end wall. High-speed visualization of the experiments from the end wall was also conducted. Oxy-syngas mixtures that were tested in the shock tube were diluted with CO2 fractions ranging from 60% – 85% by volume. A 10% fuel concentration was consistently used throughout the experiments. This study looked at the effects of changing the equivalence ratios (ϕ), between 0.33, 0.5, and 1.0 as well as changing the fuel ratio (θ), hydrogen to carbon monoxide, from 0.25, 1.0 and 4.0. The study was performed at 1.61–1.77 atm and a temperature range of 1006–1162K. The high-speed imaging was performed through a quartz end wall with a Phantom V710 camera operated at 67,065 frames per second. From the experiments, when increasing the equivalence ratio, it resulted in a longer ignition delay time. In addition, when increasing the fuel ratio, a lower ignition delay time was observed. These trends are generally expected with this combustion reaction system. The high-speed imaging showed non-homogeneous combustion in the system, however, most of the light emissions were outside the visible light range where the camera is designed for. The results were compared to predictions of two combustion chemical kinetic mechanisms: GRI v3.0 and AramcoMech v2.0 mechanisms. In general, both mechanisms did not accurately predict the experimental data. The results showed that current models are inaccurate in predicting CO2 diluted environments for syngas combustion.

Investigation on the Ignition Conditions From a Comparison Between Reacting and Non-Reacting Diesel Spray Experiments

2002 ◽  
Author(s):  
T. Kim ◽  
J. B. Ghandhi
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Equivalence Ratio ◽  
Ignition Delay Time ◽  
Ignition Time ◽  
Liquid Core ◽  
Injection Pressure ◽  
Lift Off ◽  
Injection Pressures

Natural luminosity images from reacting diesel sprays were acquired in a combustion-type constant-volume spray chamber. Using an ambient condition of 15 kg/m3 and 1000 K, the effects of peak injection pressures (60, 90 and 150 MPa) and nozzle hole sizes (140, 158 and 200 μm) were investigated. From high-speed natural luminosity cinematography, macroscopic reacting spray characteristics such as flame lift-off height and ignition delay time were obtained. For increasing injection pressures the ignition delay time decreased, and the flame lift off height increased. For increasing hole diameter the ignition time delay decreased, and the flame lift-off height decreased. The authors’ previous results of the fuel concentration measurement from non-reacting spray experiments were used to ascertain the local equivalence ratio for the reacting spray during the ignition and initial flame development period. The first detection of the luminosity (believed to be chemiluminescence) signal was found to occur in fuel-rich vapor regions near the boundary of the liquid core with an equivalence ratio near 2 and a temperature of approximately 800 K. These conditions were found to be independent of injection pressure and nozzle diameter for the condition tested (15 kg/m3 and 1000 K ambient), suggesting that this is a kinetically controlled process.

Effect of Turbocharged Diesel Engine Operating Conditions on Intake Premixed Methanol Quantity and Performance

2014 ◽  
Vol 1008-1009 ◽  
pp. 951-955
Author(s):  
Deng Pan Zhang ◽  
Jia Yi Du ◽  
Yin Nan Yuan ◽  
Sheng Li Wei
Keyword(s):  
Diesel Engine ◽  
Ignition Delay ◽  
Delay Time ◽  
High Speed ◽  
Ignition Delay Time ◽  
Operating Conditions ◽  
Injection System ◽  
Turbocharged Diesel Engine ◽  
Low Speed ◽  
Hc Emissions

A multi-point low-pressure methanol injection system was installed on manifold of a four cylinder turbocharged diesel engine, and the experiments on the engine operated with intake premixed methanol were conducted under wide operating conditions. The influence of the engine operating conditions on premixed methanol quantity was analyzed. The results show that, compared with straight diesel model, premixed methanol prolongs the ignition delay time of pilot diesel at the engine high load with low speed, and more methanol quantity can be premixed. At more than medium load with high speed, diesel ignition delay time with premixed methanol is shorter than with straight diesel model, and substitution ratio of methanol for diesel is significantly lower than that of low speed. Compared with the straight diesel mode at high speed, the fuel economy of the dual fueling mode is better, and NOx and soot emissions also are decreased, but CO and HC emissions are increased.

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