Sodium capture mechanism by simulated silica/aluminosilicate slag at high temperatures

Hu, Xinglei; Zhang, Zhongxiao; Wu, Xiaojiang; Hu, Fan; Li, Zixiang; Kong, Chengdong; Jiang, Yanchi; Guo, Xinwei

doi:10.1016/j.fuel.2022.125344

Cited by 8 publications

(4 citation statements)

References 37 publications

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“…This is a reasonable value which results from the boiler operating at a negative back pressure and the age of the unit. In addition, Fluids 2023, 8, 305 6 of 23 35 mass % flue gas recirculation (flue gas recirculation/total flue gas flow rate) was used to reduce temperature and control NOx. These values are in reasonable agreement with values associated with other units reported in the literature [18][19][20].…”

Section: Experimental Measurementsmentioning

confidence: 99%

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Measurements and Prediction of Ash Deposition in a Cyclone-Fired Boiler Operating under Variable Load Conditions

Krishnamoorthy,

Bloom,

Viswanathan

et al. 2023

Fluids

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Measurements of ash deposition rates were made between the secondary superheater and reheater sections of a 450 MW cyclone-fired lignite boiler as the operational load varied from 33 to 100%. Significant reductions in deposition rates with a decrease in operational load were observed. To uncover the causative mechanisms behind these observations, operational data from the power plant were used to carry out computational fluid dynamic (CFD) simulations of the boiler. After ascertaining that the gas temperatures and velocities at various sections within the boiler were being represented adequately, decoupled simulations of the ash deposition process on the deposit probe were carried out using a finely resolved boundary layer mesh. Fly ash particle size distribution (PSD) and its concentration for the decoupled calculations were determined from stand-alone cyclone barrel simulations. The ash partitioning (mass %) between the fly ash and slag was found to be ~50:50, which was in line with previous field observations, and it did not vary significantly across different cyclone loads. The predicted PSD of the deposit ash was concentrated in the size range 10–30 microns, which was in agreement with cross-sectional images of the deposit obtained from the measurements. At lower loads, sharp variations in the deposition rates were predicted in the gas temperature range 950–1150 K. The particle kinetic energy—particle viscosity-based capture methodology utilized in this study in conjunction with appropriate ash compositions, ash viscosity models and gas temperature estimates can help estimate slagging propensities at different loads reasonably well in these systems.

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Section: Experimental Measurementsmentioning

confidence: 99%

“…However, it is worth mentioning that the B/A ratio (cf. Equation ( 1)) can have a significant impact on the slag to fly ash partitioning and significantly impact this ratio and the slag composition [35,36].…”

mentioning

confidence: 99%

Measurements and Prediction of Ash Deposition in a Cyclone-Fired Boiler Operating under Variable Load Conditions

Krishnamoorthy,

Bloom,

Viswanathan

et al. 2023

Fluids

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“…The extent of silicate formation during coal combustion has been systematically studied, considering factors such as temperature, 15,17 alkali concentration, 18 silica particle size, 19 SO 2 in flue gas, 20 and other minerals. 17,21,22 It is generally observed that the rate of ASR increases with temperature but is limited by the size of silica particles, which reduces the available surface area for the reaction. Additionally, other mineral components in the fuel, such as silica−aluminates, impact the degree of reaction between NaCl and SiO 2 , as metal chloride molecules tend to be adsorbed on aluminum (Al) sites.…”

Section: Introductionmentioning

confidence: 99%

“…Sodium (Na) primarily exists in coal in the form of water-soluble NaCl, and the formation of Na-silicates during the thermal conversion of coal has been extensively studied. , Kosminski et al , discovered that Na 2 Si 2 O 5 is formed by the reaction between NaCl and SiO 2 in the presence of steam at a temperature above 750 °C during coal gasification. The extent of silicate formation during coal combustion has been systematically studied, considering factors such as temperature, , alkali concentration, silica particle size, SO 2 in flue gas, and other minerals. ,, It is generally observed that the rate of ASR increases with temperature but is limited by the size of silica particles, which reduces the available surface area for the reaction. Additionally, other mineral components in the fuel, such as silica–aluminates, impact the degree of reaction between NaCl and SiO 2 , as metal chloride molecules tend to be adsorbed on aluminum (Al) sites .…”

Section: Introductionmentioning

confidence: 99%

Promoting Silicate Formation by Alkali Chloride Solid Solution during Thermal Conversion of Silicon-Containing Solid Fuels

Cheng,

Chen,

Zhu

et al. 2024

Energy Fuels

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The development of solid fuel combustion power generation technology in China has been significantly hindered by alkali-related issues including fouling, slagging, and particulate matter emission. Consequently, understanding the formation of silicates in the alkali–silica reaction (ASR) becomes crucial for addressing alkali-related issues associated with solid fuels. However, the complex composition of these fuels and the unknown interaction between multiple alkali chlorides (NaCl and KCl) hinder a comprehensive understanding of ASR. This study investigates the role of alkali chloride solid solution, which contains both Na and K, in silicate formation during ASR. The results reveal that the inclusion of K has three positive effects on silicate formation: the creation of lattice defects, the formation of nano protrusion structures, and the reduction of thermal stability. These effects contribute to higher yields of silicates in ASR, primarily by promoting the formation of SiO4 tetrahedra with three bridge oxygen atoms (Q 3 structures). Moreover, a molecular-scale analysis suggests that the presence of K facilitates the dissociation of NaCl within the Q 3 and NaCl dimer, thereby favoring silicate formation. This research provides valuable insights into the mechanisms of ASR in the presence of multiple alkali chlorides during the thermal conversion of silicon-containing solid fuels.

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Inhibiting agglomeration of bed particles in CFB burning high-alkali fuel: Experiment, mechanisms and criteria for recirculating bottom ash or selecting alternative bed materials

Long,

Li,

et al. 2024

Energy

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Sodium capture mechanism by simulated silica/aluminosilicate slag at high temperatures

Cited by 8 publications

References 37 publications

Measurements and Prediction of Ash Deposition in a Cyclone-Fired Boiler Operating under Variable Load Conditions

Measurements and Prediction of Ash Deposition in a Cyclone-Fired Boiler Operating under Variable Load Conditions

Promoting Silicate Formation by Alkali Chloride Solid Solution during Thermal Conversion of Silicon-Containing Solid Fuels

Inhibiting agglomeration of bed particles in CFB burning high-alkali fuel: Experiment, mechanisms and criteria for recirculating bottom ash or selecting alternative bed materials

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