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Ning Li - One of the best experts on this subject based on the ideXlab platform.

  • conversions of fuel n volatile n and char n to no and n2o during Combustion of a single coal particle in o2 n2 and o2 h2o at low temperature
    Chinese Journal of Chemical Engineering, 2018
    Co-Authors: Yuan Li, Hao Zhou, Ning Li
    Abstract:

    Abstract Oxy-steam Combustion is a promising next-generation Combustion technology. Conversions of fuel-N, volatile-N, and char-N to NO and N2O during Combustion of a single coal particle in O2/N2 and O2/H2O were studied in a tube reactor at low temperature. In O2/N2, NO reaches the maximum value in the devolatilization Stage and N2O reaches the maximum value in the char Combustion Stage. In O2/H2O, both NO and N2O reach the maximum values in the char Combustion Stage. The total conversion ratios of fuel-N to NO and N2O in O2/N2 are obviously higher than those in O2/H2O, due to the reduction of H2O on NO and N2O. Temperature changes the trade-off between NO and N2O. In O2/N2 and O2/H2O, the conversion ratios of fuel-N, volatile-N, and char-N to NO increase with increasing temperature, and those to N2O show the opposite trends. The conversion ratios of fuel-N, volatile-N, and char-N to NO reach the maximum values at  = 30 vol% in O2/N2. In O2/H2O, the conversion ratios of fuel-N and char-N to NO reach the maximum values at  = 30 vol%, and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration. The conversion ratios of fuel-N, volatile-N, and char-N to N2O decrease with increasing oxygen concentration in both atmospheres. A higher coal rank has higher conversion ratios of fuel-N to NO and N2O. Anthracite coal exhibits the highest conversion ratios of fuel-N, volatile-N, and char-N to NO and N2O in both atmospheres. This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere.

  • conversions of fuel n to no and n2o during devolatilization and char Combustion Stages of a single coal particle under oxy fuel fluidized bed conditions
    Journal of The Energy Institute, 2018
    Co-Authors: Hao Zhou, Yuan Li, Ning Li
    Abstract:

    Abstract The conversions of fuel-N to NO and N2O during devolatilization and char Combustion Stages of a single coal particle of 7 mm in diameter were investigated in a laboratory-scale flow tube reactor under oxy-fuel fluidized bed (FB) conditions. The method of isothermal thermo-gravimetric analysis (TGA) combing with the coal properties was proposed to distinguish the devolatilization and char Combustion Stages of coal Combustion. The results show that the char Combustion Stage plays a dominant role in NO and N2O emissions in oxy-fuel FB Combustion. Temperature changes the trade-off between NO and N2O during the two Stages. With increasing temperature, the conversion ratios of fuel-N to NO during the two Stages increase, and the opposite tendencies are observed for N2O. CO2 inhibits the fuel-N conversions to NO during the two Stages but promotes those to N2O. Compared with air Combustion, the conversion ratios of fuel-N to NO during the two Stages are lower in 21%O2/79%CO2, and those to N2O are higher. At  = 21–50% by volume, the conversion ratios of fuel-N to NO during the two Stages reach the maximum values at  = 30% by volume, and those to N2O decrease with increasing O2 concentration. H2O suppresses the fuel-N conversions to NO and N2O during the two Stages. A higher coal rank has higher total conversion ratios of fuel-N to NO and N2O. Fuel-N, volatile matter, and fixed carbon contents are the important factors on fuel-N conversions to NO and N2O during the two Stages. The results benefit the understanding of NO and N2O emission mechanisms during oxy-fuel FB Combustion of coal.

  • experimental study of the no and n2o emissions during devolatilization and char Combustion of a single biomass particle in o2 n2 and o2 h2o under low temperature condition
    Fuel, 2017
    Co-Authors: Hao Zhou, Ning Li, Yuan Li, Sheng Meng
    Abstract:

    Abstract Oxy-H 2 O Combustion is a novel oxy-fuel Combustion technology, different from conventional and oxy-CO 2 Combustion. NO and N 2 O emissions during devolatilization and char Combustion of a single biomass particle in O 2 /N 2 and O 2 /H 2 O were investigated in a tube reactor under different temperatures (700 °C, 800 °C, and 900 °C) and oxygen concentrations (21%, 30%, 40%, and 50% by volume). Single biomass pellets of poplar wood, rice husk, and corn stalk were selected. The method of isothermal thermo-gravimetric analysis was applied to distinguish the two Stages of biomass Combustion based on its proximate analysis. The presence of H 2 O vapor can improve the free radicals, H 2 and CO concentrations, promoting NO and N 2 O reduction. The total conversions of fuel-N to NO and N 2 O in O 2 /N 2 are over 2 times higher than those in O 2 /H 2 O. In O 2 /N 2 , NO is formed as the sample heated up, while N 2 O is mainly formed during char Combustion Stage. However, NO is formed after N 2 O in O 2 /H 2 O. No matter in O 2 /N 2 or in O 2 /H 2 O, a higher fuel-N content in biomass results in higher NO and N 2 O yields during the two Stages, whilst the conversions of fuel-N to NO and N 2 O during the two Stages decrease with increasing fuel-N/ash content. In O 2 /N 2 , the total conversion of fuel-N to NO reaches the maximum value (14.35%) at T = 800 °C, whilst the total conversion of fuel-N to NO increases with increasing temperature in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing temperature in O 2 /N 2 and O 2 /H 2 O. The influence of oxygen concentration on NO and N 2 O is similar to that of temperature. In O 2 /N 2 , there is a maximum value of the total conversion of fuel-N to NO (14.35%) at 〈O 2 〉 = 30%, whilst there is no obvious change of the total conversion of fuel-N to NO with increasing oxygen concentration in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing oxygen concentration in O 2 /N 2 and O 2 /H 2 O. The results are beneficial to understand the NO and N 2 O emission mechanisms and favorable for the NO and N 2 O control in O 2 /H 2 O.

  • no and n2o emissions during devolatilization and char Combustion of a single biomass particle under oxy fuel conditions at fluidized bed temperature
    Energy & Fuels, 2017
    Co-Authors: Hao Zhou, Ning Li
    Abstract:

    Oxy-fuel fluidized bed Combustion is a novel clean-biomass utilization technology. The NO and N2O emissions during oxy-fuel Combustion of a single biomass particle at fluidized bed temperature were studied in a flow tube reactor. The method of isothermal thermogravimetric analysis was used to distinguish the devolatilization and char Combustion Stages of biomass Combustion. This work is aimed to study the effects of temperature, CO2 concentration, atmosphere and O2 concentration, H2O vapor addition, and biomass type on the NO and N2O emissions during oxy-fuel Combustion of a single biomass particle at fluidized bed temperature. In oxy-fuel Combustion, NO is rapidly formed during the devolatilization Stage, while N2O is mainly formed during the char Combustion Stage. In 30% O2/70% CO2 at T = 800 °C, the conversions of fuel-N to NO and N2O are 11.96% and 18.98%, respectively. The conversion of fuel-N to NO reaches the maximum value at T = 800 °C during the devolatilization Stage, while it increases with inc...

Hao Zhou - One of the best experts on this subject based on the ideXlab platform.

  • conversions of fuel n volatile n and char n to no and n2o during Combustion of a single coal particle in o2 n2 and o2 h2o at low temperature
    Chinese Journal of Chemical Engineering, 2018
    Co-Authors: Yuan Li, Hao Zhou, Ning Li
    Abstract:

    Abstract Oxy-steam Combustion is a promising next-generation Combustion technology. Conversions of fuel-N, volatile-N, and char-N to NO and N2O during Combustion of a single coal particle in O2/N2 and O2/H2O were studied in a tube reactor at low temperature. In O2/N2, NO reaches the maximum value in the devolatilization Stage and N2O reaches the maximum value in the char Combustion Stage. In O2/H2O, both NO and N2O reach the maximum values in the char Combustion Stage. The total conversion ratios of fuel-N to NO and N2O in O2/N2 are obviously higher than those in O2/H2O, due to the reduction of H2O on NO and N2O. Temperature changes the trade-off between NO and N2O. In O2/N2 and O2/H2O, the conversion ratios of fuel-N, volatile-N, and char-N to NO increase with increasing temperature, and those to N2O show the opposite trends. The conversion ratios of fuel-N, volatile-N, and char-N to NO reach the maximum values at  = 30 vol% in O2/N2. In O2/H2O, the conversion ratios of fuel-N and char-N to NO reach the maximum values at  = 30 vol%, and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration. The conversion ratios of fuel-N, volatile-N, and char-N to N2O decrease with increasing oxygen concentration in both atmospheres. A higher coal rank has higher conversion ratios of fuel-N to NO and N2O. Anthracite coal exhibits the highest conversion ratios of fuel-N, volatile-N, and char-N to NO and N2O in both atmospheres. This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere.

  • conversions of fuel n to no and n2o during devolatilization and char Combustion Stages of a single coal particle under oxy fuel fluidized bed conditions
    Journal of The Energy Institute, 2018
    Co-Authors: Hao Zhou, Yuan Li, Ning Li
    Abstract:

    Abstract The conversions of fuel-N to NO and N2O during devolatilization and char Combustion Stages of a single coal particle of 7 mm in diameter were investigated in a laboratory-scale flow tube reactor under oxy-fuel fluidized bed (FB) conditions. The method of isothermal thermo-gravimetric analysis (TGA) combing with the coal properties was proposed to distinguish the devolatilization and char Combustion Stages of coal Combustion. The results show that the char Combustion Stage plays a dominant role in NO and N2O emissions in oxy-fuel FB Combustion. Temperature changes the trade-off between NO and N2O during the two Stages. With increasing temperature, the conversion ratios of fuel-N to NO during the two Stages increase, and the opposite tendencies are observed for N2O. CO2 inhibits the fuel-N conversions to NO during the two Stages but promotes those to N2O. Compared with air Combustion, the conversion ratios of fuel-N to NO during the two Stages are lower in 21%O2/79%CO2, and those to N2O are higher. At  = 21–50% by volume, the conversion ratios of fuel-N to NO during the two Stages reach the maximum values at  = 30% by volume, and those to N2O decrease with increasing O2 concentration. H2O suppresses the fuel-N conversions to NO and N2O during the two Stages. A higher coal rank has higher total conversion ratios of fuel-N to NO and N2O. Fuel-N, volatile matter, and fixed carbon contents are the important factors on fuel-N conversions to NO and N2O during the two Stages. The results benefit the understanding of NO and N2O emission mechanisms during oxy-fuel FB Combustion of coal.

  • experimental study of the no and n2o emissions during devolatilization and char Combustion of a single biomass particle in o2 n2 and o2 h2o under low temperature condition
    Fuel, 2017
    Co-Authors: Hao Zhou, Ning Li, Yuan Li, Sheng Meng
    Abstract:

    Abstract Oxy-H 2 O Combustion is a novel oxy-fuel Combustion technology, different from conventional and oxy-CO 2 Combustion. NO and N 2 O emissions during devolatilization and char Combustion of a single biomass particle in O 2 /N 2 and O 2 /H 2 O were investigated in a tube reactor under different temperatures (700 °C, 800 °C, and 900 °C) and oxygen concentrations (21%, 30%, 40%, and 50% by volume). Single biomass pellets of poplar wood, rice husk, and corn stalk were selected. The method of isothermal thermo-gravimetric analysis was applied to distinguish the two Stages of biomass Combustion based on its proximate analysis. The presence of H 2 O vapor can improve the free radicals, H 2 and CO concentrations, promoting NO and N 2 O reduction. The total conversions of fuel-N to NO and N 2 O in O 2 /N 2 are over 2 times higher than those in O 2 /H 2 O. In O 2 /N 2 , NO is formed as the sample heated up, while N 2 O is mainly formed during char Combustion Stage. However, NO is formed after N 2 O in O 2 /H 2 O. No matter in O 2 /N 2 or in O 2 /H 2 O, a higher fuel-N content in biomass results in higher NO and N 2 O yields during the two Stages, whilst the conversions of fuel-N to NO and N 2 O during the two Stages decrease with increasing fuel-N/ash content. In O 2 /N 2 , the total conversion of fuel-N to NO reaches the maximum value (14.35%) at T = 800 °C, whilst the total conversion of fuel-N to NO increases with increasing temperature in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing temperature in O 2 /N 2 and O 2 /H 2 O. The influence of oxygen concentration on NO and N 2 O is similar to that of temperature. In O 2 /N 2 , there is a maximum value of the total conversion of fuel-N to NO (14.35%) at 〈O 2 〉 = 30%, whilst there is no obvious change of the total conversion of fuel-N to NO with increasing oxygen concentration in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing oxygen concentration in O 2 /N 2 and O 2 /H 2 O. The results are beneficial to understand the NO and N 2 O emission mechanisms and favorable for the NO and N 2 O control in O 2 /H 2 O.

  • no and n2o emissions during devolatilization and char Combustion of a single biomass particle under oxy fuel conditions at fluidized bed temperature
    Energy & Fuels, 2017
    Co-Authors: Hao Zhou, Ning Li
    Abstract:

    Oxy-fuel fluidized bed Combustion is a novel clean-biomass utilization technology. The NO and N2O emissions during oxy-fuel Combustion of a single biomass particle at fluidized bed temperature were studied in a flow tube reactor. The method of isothermal thermogravimetric analysis was used to distinguish the devolatilization and char Combustion Stages of biomass Combustion. This work is aimed to study the effects of temperature, CO2 concentration, atmosphere and O2 concentration, H2O vapor addition, and biomass type on the NO and N2O emissions during oxy-fuel Combustion of a single biomass particle at fluidized bed temperature. In oxy-fuel Combustion, NO is rapidly formed during the devolatilization Stage, while N2O is mainly formed during the char Combustion Stage. In 30% O2/70% CO2 at T = 800 °C, the conversions of fuel-N to NO and N2O are 11.96% and 18.98%, respectively. The conversion of fuel-N to NO reaches the maximum value at T = 800 °C during the devolatilization Stage, while it increases with inc...

Jun Deng - One of the best experts on this subject based on the ideXlab platform.

  • assessing the effectiveness of a high temperature programmed experimental system for simulating the spontaneous Combustion properties of bituminous coal through thermokinetic analysis of four oxidation Stages
    Energy, 2019
    Co-Authors: Jun Deng, Jingyu Zhao, Yanni Zhang, Tao Wang, Jiajia Song, Qiang Zeng
    Abstract:

    Abstract The spontaneous Combustion of coal is characterized by high-temperature oxidation. This study used a self-made programmed experimental system to maintain temperature parameters at specified levels to simulate the Combustion properties of coal. The oxygen concentration was determined to be inversely proportional to indicator gas concentrations. Five characteristic temperatures were achieved: critical temperature (97.45 ± 7.15 °C), crack temperature (149.28 ± 8.32 °C), active temperature (206.95 ± 15.05 °C), speedup temperature (263.45 ± 6.35 °C), and ignition temperature (390.85 ± 27.05 °C). Thermal characteristics were analyzed by dividing the oxidation into the following temperature Stages: the critical temperature Stage, crack–active–speedup temperature Stage, speedup-ignition temperature Stage, and Combustion Stage. Furthermore, the differential and integral kinetic methods were used to compute the apparent activation energy in the four aforementioned Stages. The results indicated that the apparent activation energies decreased through the first three Stages and then increased in the fourth Stage. Therefore, the crack–active–speedup temperature Stage was determined to be potentially dangerous during oxidation because gases increased rapidly at this Stage; such gases included CO, which is particularly harmful to human health. The thermal energy release also increased gradually at this Stage.

  • comparative analysis of thermokinetic behavior and gaseous products between first and second coal spontaneous Combustion
    Fuel, 2018
    Co-Authors: Yang Xiao, Jun Deng
    Abstract:

    Abstract To investigate the entire process of first and second coal spontaneous Combustion, a 15-t experimental furnace for coal spontaneous Combustion and synchronous thermal analyzer coupled with Fourier transform infrared spectroscopy were employed. The process of experimental tests was as follows: First, coal temperature was increased from 31.0 °C (room temperature) to 452.7 °C without intervention. Second, the coal sample was cooled to approximately 90.0 °C in an anaerobic atmosphere. Third, air was supplied until the sample reached 418.0 °C. Finally, the coal was cooled again to 100.0 °C in an anaerobic atmosphere. The variations of temperature, mass, heat energy intensity, and gaseous products were investigated. The results indicated that the temperature change rate first increased and then decreased during the first and second coal spontaneous Combustion. Compared with the first coal spontaneous Combustion, the rates of temperature and mass loss change with a heating rate of 2.5 °C/min were higher at the Combustion Stage of the second coal spontaneous Combustion, but the variations of the exothermic reaction rate and mass loss with other heating rates (5.0, 10.0, and 15.0 °C/min) were lower. The differences among CO, CO2, alkanes, and alkenes during the first and second coal spontaneous Combustions were insignificant until 300.0 °C. However, the emission of CO and CO2 during the second coal spontaneous Combustion was significantly higher than during the first coal spontaneous Combustion, whereas the release of alkanes and alkenes was substantially weaker when the temperature was higher than 300.0 °C. Moreover, the amount of H2O during the first coal spontaneous Combustion was higher than that during the second coal spontaneous Combustion.

  • thermal analysis of the pyrolysis and oxidation behaviour of 1 3 coking coal
    Journal of Thermal Analysis and Calorimetry, 2017
    Co-Authors: Jun Deng, Yang Xiao, Jingyu Zhao, Yanni Zhang, Anchi Huang
    Abstract:

    Pyrolysis is the initial Stage of coal conversion during processes including Combustion, gasification, and liquefaction. It has a direct effect on coal’s subsequent transformation. Pyrolysis plays a vital role in the efficiency of coal’s use and, like oxidation, can create hazards during non-Combustion processing (such as during mining or transportation). Indeed, the spontaneous Combustion of coal (a coal–oxygen reaction) can impact human health, lead to material damage and wasted resources, and damage the environment. To better understand this phenomenon, samples of bituminous 1/3 coking were taken from four different coal mines in Huainan (Anhui, China) and analysed. Thermogravimetry and differential scanning calorimetry are adopted to explore the samples’ thermal behaviour. The complex kinetics of the pyrolysis process are divided into four Stages, while that of oxidation is divided into five. The influence of heating rates is analysed separately for oxidation and pyrolysis. Furthermore, the apparent activation energy is calculated for the Combustion Stage of the oxidation process, and curve fitting is used to identify the most probable mechanism function.

Yuan Li - One of the best experts on this subject based on the ideXlab platform.

  • conversions of fuel n volatile n and char n to no and n2o during Combustion of a single coal particle in o2 n2 and o2 h2o at low temperature
    Chinese Journal of Chemical Engineering, 2018
    Co-Authors: Yuan Li, Hao Zhou, Ning Li
    Abstract:

    Abstract Oxy-steam Combustion is a promising next-generation Combustion technology. Conversions of fuel-N, volatile-N, and char-N to NO and N2O during Combustion of a single coal particle in O2/N2 and O2/H2O were studied in a tube reactor at low temperature. In O2/N2, NO reaches the maximum value in the devolatilization Stage and N2O reaches the maximum value in the char Combustion Stage. In O2/H2O, both NO and N2O reach the maximum values in the char Combustion Stage. The total conversion ratios of fuel-N to NO and N2O in O2/N2 are obviously higher than those in O2/H2O, due to the reduction of H2O on NO and N2O. Temperature changes the trade-off between NO and N2O. In O2/N2 and O2/H2O, the conversion ratios of fuel-N, volatile-N, and char-N to NO increase with increasing temperature, and those to N2O show the opposite trends. The conversion ratios of fuel-N, volatile-N, and char-N to NO reach the maximum values at  = 30 vol% in O2/N2. In O2/H2O, the conversion ratios of fuel-N and char-N to NO reach the maximum values at  = 30 vol%, and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration. The conversion ratios of fuel-N, volatile-N, and char-N to N2O decrease with increasing oxygen concentration in both atmospheres. A higher coal rank has higher conversion ratios of fuel-N to NO and N2O. Anthracite coal exhibits the highest conversion ratios of fuel-N, volatile-N, and char-N to NO and N2O in both atmospheres. This work is to develop efficient ways to understand and control NO and N2O emissions for a clean and sustainable atmosphere.

  • conversions of fuel n to no and n2o during devolatilization and char Combustion Stages of a single coal particle under oxy fuel fluidized bed conditions
    Journal of The Energy Institute, 2018
    Co-Authors: Hao Zhou, Yuan Li, Ning Li
    Abstract:

    Abstract The conversions of fuel-N to NO and N2O during devolatilization and char Combustion Stages of a single coal particle of 7 mm in diameter were investigated in a laboratory-scale flow tube reactor under oxy-fuel fluidized bed (FB) conditions. The method of isothermal thermo-gravimetric analysis (TGA) combing with the coal properties was proposed to distinguish the devolatilization and char Combustion Stages of coal Combustion. The results show that the char Combustion Stage plays a dominant role in NO and N2O emissions in oxy-fuel FB Combustion. Temperature changes the trade-off between NO and N2O during the two Stages. With increasing temperature, the conversion ratios of fuel-N to NO during the two Stages increase, and the opposite tendencies are observed for N2O. CO2 inhibits the fuel-N conversions to NO during the two Stages but promotes those to N2O. Compared with air Combustion, the conversion ratios of fuel-N to NO during the two Stages are lower in 21%O2/79%CO2, and those to N2O are higher. At  = 21–50% by volume, the conversion ratios of fuel-N to NO during the two Stages reach the maximum values at  = 30% by volume, and those to N2O decrease with increasing O2 concentration. H2O suppresses the fuel-N conversions to NO and N2O during the two Stages. A higher coal rank has higher total conversion ratios of fuel-N to NO and N2O. Fuel-N, volatile matter, and fixed carbon contents are the important factors on fuel-N conversions to NO and N2O during the two Stages. The results benefit the understanding of NO and N2O emission mechanisms during oxy-fuel FB Combustion of coal.

  • experimental study of the no and n2o emissions during devolatilization and char Combustion of a single biomass particle in o2 n2 and o2 h2o under low temperature condition
    Fuel, 2017
    Co-Authors: Hao Zhou, Ning Li, Yuan Li, Sheng Meng
    Abstract:

    Abstract Oxy-H 2 O Combustion is a novel oxy-fuel Combustion technology, different from conventional and oxy-CO 2 Combustion. NO and N 2 O emissions during devolatilization and char Combustion of a single biomass particle in O 2 /N 2 and O 2 /H 2 O were investigated in a tube reactor under different temperatures (700 °C, 800 °C, and 900 °C) and oxygen concentrations (21%, 30%, 40%, and 50% by volume). Single biomass pellets of poplar wood, rice husk, and corn stalk were selected. The method of isothermal thermo-gravimetric analysis was applied to distinguish the two Stages of biomass Combustion based on its proximate analysis. The presence of H 2 O vapor can improve the free radicals, H 2 and CO concentrations, promoting NO and N 2 O reduction. The total conversions of fuel-N to NO and N 2 O in O 2 /N 2 are over 2 times higher than those in O 2 /H 2 O. In O 2 /N 2 , NO is formed as the sample heated up, while N 2 O is mainly formed during char Combustion Stage. However, NO is formed after N 2 O in O 2 /H 2 O. No matter in O 2 /N 2 or in O 2 /H 2 O, a higher fuel-N content in biomass results in higher NO and N 2 O yields during the two Stages, whilst the conversions of fuel-N to NO and N 2 O during the two Stages decrease with increasing fuel-N/ash content. In O 2 /N 2 , the total conversion of fuel-N to NO reaches the maximum value (14.35%) at T = 800 °C, whilst the total conversion of fuel-N to NO increases with increasing temperature in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing temperature in O 2 /N 2 and O 2 /H 2 O. The influence of oxygen concentration on NO and N 2 O is similar to that of temperature. In O 2 /N 2 , there is a maximum value of the total conversion of fuel-N to NO (14.35%) at 〈O 2 〉 = 30%, whilst there is no obvious change of the total conversion of fuel-N to NO with increasing oxygen concentration in O 2 /H 2 O. The total conversions of fuel-N to N 2 O decrease with increasing oxygen concentration in O 2 /N 2 and O 2 /H 2 O. The results are beneficial to understand the NO and N 2 O emission mechanisms and favorable for the NO and N 2 O control in O 2 /H 2 O.

Yaqing Li - One of the best experts on this subject based on the ideXlab platform.

  • risk evaluation of coal spontaneous Combustion on the basis of auto ignition temperature
    Fuel, 2018
    Co-Authors: Yutao Zhang, Weifeng Wang, Chaoping Yang, Yaqing Li
    Abstract:

    Abstract The spontaneous Combustion of coal, if not eradicated immediately, may lead to coal ignition and even a full-blown fire. A new method, DSC Inflection Point (DSCIP), was proposed to determine the coal auto-ignition temperature (CAIT). Heat fluxes and kinetic parameters before and after CAIT were comparatively investigated through TG/DSC analysis and mathematical model construction. Meanwhile, the impacts of temperature rise rate and oxygen concentration on CAIT were studied and two indexes representing the hazard and destructiveness of coal spontaneous Combustion, respectively, were proposed. The results demonstrated that the heat flux curve of coal spontaneous Combustion can be well fitted using Gaussian mixture model. Compared to the oxidation Stage, the released heat during the Combustion Stage was greatly increased. Furthermore, the activation energy became larger and the reaction order decreased to zero when the temperature exceeded CAIT. The study also found that CAIT was enhanced with the increase of temperature rise rates or the decrease of oxygen concentrations. Changes of heat flux, free radicals, and the activation energy proved the rationality and feasibility of the DSCIP method in determining CAIT. Additionally, under the same environmental conditions, lignite had the largest hazard of coal spontaneous Combustion and the anthracite had the biggest destructiveness. Both the hazard and the destructiveness of coal spontaneous Combustion became stronger as oxygen concentrations increased.

  • characteristics of mass heat and gaseous products during coal spontaneous Combustion using tg dsc ftir technology
    Journal of Thermal Analysis and Calorimetry, 2018
    Co-Authors: Yutao Zhang, Yaqing Li, Yao Huang, Shanshan Li, Weifeng Wang
    Abstract:

    Spontaneous Combustion, if not eradicated immediately, may lead to coal ignition and even a full-blown fire. An understanding of the characteristics of coal oxidation under various environmental conditions is conducive to the reveal of the mechanism and the prevention of coal spontaneous Combustion. TG/DSC–FTIR coupling technology was employed to investigate the evolutions of coal mass, heat and gaseous products during coal spontaneous Combustion. The experiments conclude that the mass loss rate in Combustion Stage was much higher than other Stages and the major of coal mass (over 80%) was consumed at this Stage. As the oxygen concentration decreased, the Combustion of coal was evidently postponed and the exothermic region shifted to a higher temperature. Correspondingly, the temperatures at which productions of CO and CO2 reached to the maximum were deferred as well. Experimental results also indicated that heating rates behaved differently before and after the ignition temperature. The mass loss rates of coal were independent of heating rates before ignition temperatures but obviously expanded and moved to higher temperatures after exceeding the ignition temperature. Additionally, with the increase of the heating rates, the exothermic region shifted to higher temperatures and the release of CO and CO2 were delayed and reached to the maximum in a longer time.