Influence of External Clay and Inherent Minerals on Lignite Optical Ignition and Volatile Flame Propagation in Air-Firing and Oxy-Firing

Prationo, Wirhan; Zhang, Jian; Abbas, Hawra Ali Abdul; Wu, Xiaojiang; Chen, Xiao

doi:10.1021/ie402600p

Cited by 7 publications

(7 citation statements)

References 32 publications

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“…The sulfur content is also very low, accounting for 0.33 wt% on the mass basis of dried coal. In addition, the coal has a relatively high volatile content, which is released at a comparable rate with the published results for bituminous coals [20]. The char-O 2 reactivity of the lignite studied here is much higher than that of bituminous coal, due to the catalytic effects of its ash-forming metals [20].…”

Section: Properties Of Lignite Coal Sample and Silica Additivesupporting

confidence: 81%

“…In addition, the coal has a relatively high volatile content, which is released at a comparable rate with the published results for bituminous coals [20]. The char-O 2 reactivity of the lignite studied here is much higher than that of bituminous coal, due to the catalytic effects of its ash-forming metals [20]. For the muffle furnace ash of the raw coal, its melting commences at 1240°C and 1300°C under reducing and oxidising environments, respectively.…”

Section: Properties Of Lignite Coal Sample and Silica Additivesupporting

confidence: 78%

“…For either raw coal or coal mixed with silica case, the flue gas temperature below the platen superheater was around 1300°C, which is close to ash fusion temperatures listed in Table 2. The added silica is suggested to slightly increase coal flame temperature due to its catalytic effect on promoting the cracking of volatiles into light hydrocarbons [20]. Such an effect is however marginal, if not negligible here.…”

Section: Mw Th Pulverised Coal-fired Boiler For Combustion Testmentioning

confidence: 79%

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Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler. Part 1. Changes on the properties of ash deposits along the furnace

Dai

Girolamo

et al. 2015

Fuel

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103

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Section: Properties Of Lignite Coal Sample and Silica Additivesupporting

confidence: 81%

Section: Properties Of Lignite Coal Sample and Silica Additivesupporting

confidence: 78%

Section: Mw Th Pulverised Coal-fired Boiler For Combustion Testmentioning

confidence: 79%

See 1 more Smart Citation

Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler. Part 1. Changes on the properties of ash deposits along the furnace

Dai

Girolamo

et al. 2015

Fuel

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103

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“…The FFBR was operated at atmospheric pressure with a measured flame temperature of approximately 1062°C before the feeding of coal/char. A magnitude of 10 5 °C/s is expected for the heat-up of coal/char particles in the FFBR 18 , which is close to the industrial blast furnace heating rate 3 . Oxygen fraction was fixed at 0.21 and the O 2 /C molar ratio was fixed at 2.5.…”

Section: Flat Flame Burner Reactor (Ffbr) Experimentsmentioning

confidence: 56%

“…A high-speed camera was used to measure particle velocity and, thus, calculate the ignition time. Further information about the FFBR can be found in a previous study …”

Section: Experimental Methodologiesmentioning

confidence: 99%

Ignitability and Combustibility of Yallourn Pyrolysis Char Blended with Pulverized Coal Injection Coal under Simulated Blast Furnace Conditions

et al. 2016

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Pulverized coal injection (PCI) is a widely used blast furnace technology aimed at reducing costs and increasing productivity. The prospect of blending PCI coal with a lower cost char, derived from Yallourn brown coal, is evaluated in this study by means of thermogravimetric analysis (TGA), flat flame burner reactor and drop tube furnace experiments at four different blending ratios as well as CFD modelling. Yallourn char has desirable properties compared to PCI coal including a lower ash content and a higher heating value, although the reactivity is lower and ignition temperature is higher. Since the combustion behaviour of a blend is not always easily predicable based on the performance of the individual parent fuels, two Yallourn char samples (YC-1 and YC-2) are analysed after blending with PCI coal at four ratios. According to particle ignition time, a maximum 40 wt% is allowable for YC-1 char which is comparably reactive with the commercial PCI coal.However, a maximum 20 wt% is only allowed for YC-2 which is less reactive. The negative heat sink effect of YC-2 char is influential, whereas the heterogeneous ignition of YC -1 overlapped considerably with the ignition of PCI coal which is mainly in the homogeneous gas phase. In addition, it was found that the later char oxidation rate was accelerated greatly for the PCI coal blended with YC-1, irrespective of its blending ratio. In contrast, the heat sink effect is further obvious for the YC-2, the increase on the blending ratio of which greatly decreased the overall burnout rate, especially at low furnace temperatures (800°C and 900°C) and a shorter residence time such as 0.8 s. For YC-1 char, its blending ratio is insignificant in the overall burnout. Increasing the furnace temperature to 1000°C and the O 2 /C ratio of 1.2 can assist in achieving a nearly complete burnout for all of its blends, even at a short residence time of 0.8 s. In contrast, for YC-2 char, a furnace temperature of 1200°C and O 2 /C ratio of 1.2 are essential to complete the burnout of all its blends. The Yallourn pyrolysis conditions for the preparation of its char is critical. A good synergistic interaction between Yallourn char and commercial PCI in terms of reactivity is also essential for a broad blending ratio to be used in the blast furnace.

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Effect of CO2 on oxy-fuel combustion of coal-char particles in a fluidized bed: Modeling and comparison with the conventional mode of combustion

Gómez–Barea

Chen

et al. 2016

Applied Energy

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A char combustion model is developed to study the effect of CO2 on the combustion of coarse char particles under oxy−fuel conditions in a fluidized bed (FB). It is a transient one−dimensional model, taking into account the heat and mass transfer from the bed to the particle and the heterogeneous combustion and gasification of char. The model shows good ability to predict the char temperature history measured in our previous work for different combinations of O2/CO2 and O2/N2 with various coal types. Simulations are carried out to establish the role of CO2 in oxy-fuel conversion at different O2 levels, particle sizes, and bed temperatures. The model is used to analyze the relative contribution of carbon in the char consumed by CO2 (gasification) and O2 (combustion), as well as the differences of the peak temperatures and the burnout times in O2/CO2 and O2/N2 for char particles in a commercial FB combustor. The results indicate that the conversion of coarse (mm size) char particles in an oxy-FB is controlled by the diffusion of O2 both in the O2/CO2 and O2/N2 case. The burn−out time decreases with the bed temperature also in both cases.. The lower O2 diffusion rate in CO2 compared to N2, is the main reason for the longer burnout time and lower peak temperature found using O2/CO2 at bed temperatures of 1073-1173 K. In that temperature window, the contribution of the CO2 -char gasification is limited, being notable only at high bed temperature in O2/CO2, e.g. 1223 K. In such high temperature conditions (rarely expected to be found in commercial coal FBC) the predicted burnout time of a lignite char-particle becomes shorter in O2/CO2 than in O2/N2.

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Influence of External Clay and Inherent Minerals on Lignite Optical Ignition and Volatile Flame Propagation in Air-Firing and Oxy-Firing

Cited by 7 publications

References 32 publications

Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler. Part 1. Changes on the properties of ash deposits along the furnace

Inhibition of lignite ash slagging and fouling upon the use of a silica-based additive in an industrial pulverised coal-fired boiler. Part 1. Changes on the properties of ash deposits along the furnace

Ignitability and Combustibility of Yallourn Pyrolysis Char Blended with Pulverized Coal Injection Coal under Simulated Blast Furnace Conditions

Effect of CO2 on oxy-fuel combustion of coal-char particles in a fluidized bed: Modeling and comparison with the conventional mode of combustion

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