Mineral Transformation and Morphological Change during Pyrolysis and Gasification of Victorian Brown Coals in an Entrained Flow Reactor

Xu, Tao; Bhattacharya, Sankar

doi:10.1021/acs.energyfuels.9b00924

Cited by 18 publications

(6 citation statements)

References 39 publications

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“…The peaks at 890 and 610 cm –1 corresponding to Mg 2 SiO 4 appear when the treated temperature is above 1000 °C, indicating that Mg and Si are transformed into the low-temperature Mg 2 SiO 4 under high temperatures (2MgO + SiO 2 → Mg 2 SiO 4 , Δ G = −58.25 kJ/mol, 1000 °C). According to the literature, MgO is also transformed into other low-temperature eutectic compounds such as CaMgSiO 4 (CaO + MgO + SiO 2 → CaMgSiO 4 , Δ G = −105.11 kJ/mol, 1000 °C), Mg 3 Al 2 (SiO 4 ) 3 (3MgO + Al 2 O 3 + 3SiO 2 →Mg 3 Al 2 (SiO 4 ) 3 , Δ G = −72.89 kJ/mol, 1000 °C), and Mg 2 Al 4 Si 5 O 18 (2MgO + 2Al 2 O 3 + 5SiO 2 → Mg 2 Al 4 Si 5 O 18 , Δ G = −92.80 kJ/mol, 1000 °C), decreasing the ash fusion temperature significantly. , The peak at 798 cm –1 is attributed to quartz and its shape changes with the increasing temperature, indicating that the crystal structure of quartz is transformed into the low-temperature Fe 2 SiO 4 , Mg 2 SiO 4 , CaMgSiO 4 , etc., which leads to a drop in the ash fusion temperature for the coal blending of C00 and C02. It is reported that the formation of low-melting-point eutectics enriched with Ca, Al, Fe, and S during the combustion can decrease the fusion temperatures of the coal ash .…”

Section: Resultsmentioning

confidence: 99%

“…Although both CaO and FeO have a significant inhibitory effect on the formation of the high-melting-point mullite, CaO has a higher conversion effect on SiO 2 , Al 2 O 3 , and mullite than FeO. 33 The peaks at 890 and 610 cm 23,34 The peak at 798 cm −1 is attributed to quartz and its shape changes with the increasing temperature, indicating that the crystal structure of quartz is transformed into the low-temperature Fe 2 SiO 4 , Mg 2 SiO 4 , CaMgSiO 4 , etc., 35 which leads to a drop in the ash fusion temperature for the coal blending of C00 and C02. It is reported that the formation of low-melting-point eutectics enriched with Ca, Al, Fe, and S during the combustion can decrease the fusion temperatures of the coal ash.…”

Section: Effect Of Coalmentioning

confidence: 99%

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Melting Characteristics of Coal Ash and Properties of Fly Ash to Understand the Slag Formation in the Shell Gasifier

Wang

Cheng

et al. 2021

ACS Omega

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The flow temperature (FT) of the coal ash from the Liuqiao no. 2 mine in North Anhui Province (C00) is too high (∼1520 °C) to fit the Shell gasifier due to its relatively high content of SiO 2 and Al 2 O 3 . To solve this problem, a series of coals were blended with C00 with different ratios, and the relations between FT and the ash composition were investigated. The coal ash was analyzed by X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy−EDX to elucidate the mechanism of the improved ash fusion performance and the slag formation in the waste heat boiler of the gasifier. It is shown that FT is relevant to the coal ash compositions as well as the structures formed at high temperatures. The existence of alkaline oxides (CaO, MgO, and Fe 2 O 3 ) decreases the coal ash FT to a low level. The FT can decrease to <1350 °C to cater to the Shell gasifier by blending C00 and C03 with a mass ratio of 4:6 owing to the plentiful alkaline oxides in C03. The FTIR results indicate that the high flow temperature of C00 is attributed to the formation of mullite at high temperatures. The coal blending with various ratios changes the compositions of CaO, MgO, and Fe 2 O 3 , which can form some low-melting-point eutectic compounds with SiO 2 and Al 2 O 3 under high temperatures, inhibit the formation of mullite, and thus decrease the ash FT. The coal ash FT was found to have a good linear relation with the ash compositions, which can sever as a reference to the coal blending. According to the model parameters, it is shown that Mg has the most significant promoting effect on the decrease in FT of the coal ash. The caking tendency of fly ash increases with the rising Ca content and an excessive Ca-based fluxing agent used in the coal blending will lead to the aggregation of the Ca-rich clasts around the fly ash particle, resulting in the plugging of the waste heat boiler in the gasifier. Therefore, the Mg-based fluxing agent is more promising to improve the ash fusion performance and reduce the caking tendency of the coal fly ash.

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Section: Resultsmentioning

confidence: 99%

Section: Effect Of Coalmentioning

confidence: 99%

Melting Characteristics of Coal Ash and Properties of Fly Ash to Understand the Slag Formation in the Shell Gasifier

Wang

Cheng

et al. 2021

ACS Omega

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“…Currently, several types of agrochemical and biochemical processes are adapted to convert lignocellulosic residues into value-added yields. The microbial delignification joined with hydrolysis to increase biofuel yields such as methane [31], butanol [32], ethanol [33], hydrogen production [34] and fuel briquettes [35]. None of the literature reported the comparative study of four different types of walnut shells.…”

Section: Pyrolysis Setup: Pyrolysis Of Biomass In a Fixed-bed Reactormentioning

confidence: 99%

Bio-Char Characterization Produced from Walnut Shell Biomass through Slow Pyrolysis: Sustainable for Soil Amendment and an Alternate Bio-Fuel

et al. 2021

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Bio-char has the ability to isolate carbon in soils and concurrently improve plant growth and soil quality, high energy density and also it can be used as an adsorbent for water treatment. In the current work, the characteristics of four different types of bio-chars, obtained from slow pyrolysis at 375 °C, produced from hard-, medium-, thin- and paper-shelled walnut residues have been studied. Bio-char properties such as proximate, ultimate analysis, heating values, surface area, pH values, thermal degradation behavior, morphological and crystalline nature and functional characterization using FTIR were determined. The pyrolytic behavior of bio-char is studied using thermogravimetric analysis (TGA) in an oxidizing atmosphere. SEM analysis confirmed morphological change and showed heterogeneous and rough texture structure. Crystalline nature of the bio-chars is established by X-ray powder diffraction (XRD) analysis. The maximum higher heating values (HHV), high fixed carbon content and surface area obtained for walnut shells (WS) samples are found as ~ 18.4 MJ kg−1, >80% and 58 m2/g, respectively. Improvement in HHV and decrease of O/C and H/C ratios lead the bio-char samples to fall into the category of coal and confirmed their hydrophobic, carbonized and aromatized nature. From the Fourier transform infra-red spectroscopy (FTIR), it is observed that there is alteration in functional groups with increase in temperature, and illustrated higher aromaticity. This showed that bio-chars have high potential to be used as solid fuel either for direct combustion or for thermal conversion processes in boilers, kilns and furnace. Further, from surface area and pH analysis of bio-chars, it is found that WS bio-chars have similar characteristics of adsorbents used for water purifications, retention of essential elements in soil and carbon sequestration.

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“…In catalytic science, metals and their compounds are widely used as catalysts. Metals, such as Na, K, Ca, Mg, Mn, Zn, Fe, and Ni, are considered to have catalytic activity for coal pyrolysis and gasification. − Transition metals, such as Fe and Ni, and minerals, such as montmorillonite, have been shown to have a catalytic effect on organic matter. − The presence of inorganic matter can advance the peak of gas generation from organic matter in coal seams. The aim of the above research is to find a suitable catalyst to improve the yield of the product.…”

Section: Introductionmentioning

confidence: 99%

“… 5 − 10 Transition metals, such as Fe and Ni, and minerals, such as montmorillonite, have been shown to have a catalytic effect on organic matter. 11 − 14 The presence of inorganic matter can advance the peak of gas generation from organic matter in coal seams. The aim of the above research is to find a suitable catalyst to improve the yield of the product.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Catalytic Action of Intrinsic Metals in Coal Spontaneous Combustion

Qiao

Deng

et al. 2023

ACS Omega

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In order to study the effect of inherent metals in coal on spontaneous combustion, Hongmiao lignite and Hongqingliang long-flame coal were demineralized by hydrochloric acid, the raw coal and demineralized coal were characterized by Fourier transform infrared spectrometry, X-ray diffraction, and synchronous thermal analysis experiments, and the corresponding ash content was detected by inductively coupled plasma mass spectrometry. The results show that the effect of demineralization on the volatile matter of low-rank coal is small, and the change of crystallite structure is not significant. The removed parts are mainly water-soluble salts and soluble minerals, such as carbonates and metal ions, that are not tightly bound to the organic matter of coal structure. The removed metal elements are mainly alkali metals Na and K, alkaline earth metals Ca, Mg, Sr, and Ba, and transition metals Fe, Mn, Ti, and so forth. The temperatures corresponding to the end of weight loss, ignition, and maximum weight loss rates were elevated on the thermogravimetric curves of the demineralized coal samples. The heat absorbed by evaporation of water in coal and the heat released by oxidation and combustion of coal are decreased to different degrees, indicating that the spontaneous combustion tendency of coal after demineralization is reduced, and alkali metal, alkaline earth metals, and transition metals in coal have a catalytic effect on spontaneous combustion of coal. After adding the metal chelating agent ethylenediaminetetraacetic acid (EDTA), the apparent activation energy decreased by 33.08 and 2.42%, respectively. EDTA and the alkali metal, alkaline earth metal, or transition-metal ions formed a stable chelate in coal. The catalytic activity of metals is weakened or even lost, thereby inhibiting spontaneous combustion of coal, and verifying the catalytic effect of internal metals in coal on the spontaneous combustion of coal.

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Mineral Transformation and Morphological Change during Pyrolysis and Gasification of Victorian Brown Coals in an Entrained Flow Reactor

Cited by 18 publications

References 39 publications

Melting Characteristics of Coal Ash and Properties of Fly Ash to Understand the Slag Formation in the Shell Gasifier

Melting Characteristics of Coal Ash and Properties of Fly Ash to Understand the Slag Formation in the Shell Gasifier

Bio-Char Characterization Produced from Walnut Shell Biomass through Slow Pyrolysis: Sustainable for Soil Amendment and an Alternate Bio-Fuel

Experimental Study on Catalytic Action of Intrinsic Metals in Coal Spontaneous Combustion

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