Slagging behavior and mechanism of high-sodium–chlorine coal combustion in a full-scale circulating fluidized bed boiler

Zi, Jingbin; Ma, Daoyang; Wang, Xuebin; Rahman, Zia ur; Li, Hao; Liao, Shengming

doi:10.1016/j.joei.2020.06.009

Cited by 24 publications

(2 citation statements)

References 35 publications

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“…Direct combustion in furnaces is considered the most cost-effective method of biomass utilization due to previous experience gained from coal combustion as well as lower investment costs [3]. However, because biomass contains a higher percentage of alkali metals [4,5] and has a lower calorific heating value, burning only biomass could result in slagging and fouling issues in heat exchangers, as well as insufficient combustion gas temperature [6]. So far, in terms of efficiency and investment cost, the co-firing approach, which refers to the partial substitution of coal by biomass, has become a widely preferred choice for burning biomass [7].…”

Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics modeling of biomass co-firing in a 300 MW pulverized coal furnace

Sun

Wang²,

Xue³

2022

THERM SCI

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Biomass energy is one of the most accessible and readily available carbon-neutral energy options as a RES. It is regarded as a viable alternative fuel for coal combustion, particularly for biomass co-firing with pulverized coal, with numerous applications. The CFD can provide reasonably accurate solutions to complex thermo-chemical-fluid interactions, which is useful for understanding the design or retrofit of boilers and can save time, money, and effort. In this study, a CFD simulation of a 300 MW pulverized coal boiler with biomass co-firing was performed to investigate the impact of biomass co-firing with coal, considering the biomass co-firing ratio, mixing effect, and feeding temperature. The results show that the flow field in the furnace does not change significantly under different bio-mass blending ratio. Biomass co-firing can reduce peak temperatures in the furnace and make the temperature distribution more uniform. The concentration of unburned carbon in the furnace decreases as the biomass blending ratio increases. Furthermore, biomass blending has a significant impact on nitrogen oxide reduction, with NOx emissions reduced by 20% and 28%, respectively, when the biomass blending ratio is 15% and 30%. The change of parameters inside the furnace caused by the reduction of biomass powder feeding temperature about 80 K is not significant. On the other hand, co-firing biomass with coal, reduces the risk of biomass spontaneous combustion while maintaining the furnace combustion stability and boiler combustion efficiency. The optimum ratio of biomass co-firing ration is deduced in this study is up to 20%.

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Section: Introductionmentioning

confidence: 99%

Computational fluid dynamics modeling of biomass co-firing in a 300 MW pulverized coal furnace

Sun

Wang²,

Xue³

2022

THERM SCI

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“…Extensive efforts have been made to elucidate the mechanism and the possible solutions to alleviate the ash-related problems (slagging and fouling) [15,[19][20][21][22]. Based on the previous literatures, Na easily sublimates into the gas phase during combustion [17,23], while Cl and S in the coal combined with gaseous Na and forms NaCl or Na 2 SO 4 at high temperatures [24,25].…”

Section: Introductionmentioning

confidence: 99%

Co-Firing Zhundong Coal with Its Gangue: Combustion Performance, Sodium Retention and Ash Fusion Behaviors

et al. 2022

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Fouling and slagging are intractable ash-related problems for boilers burning high-sodium coals (HSC) to produce electricity or heat. Reduction and resource utilization of solid waste, coal gangues, is urgent because of stringent environmental regulations and economic benefits. Based on the sodium-rich character of Zhundong coal (ZDC) and the mineralogical features of the coal gangues (ZDG), this work investigated their co-firing performance, the sodium retention behaviors as well as the slagging and fouling tendency of the ashes. Results show that combustion performance of ZDC is not reduced despite ofthe lower reactivity of ZDG. The co-firing reaction follows the 3D diffusion model (cylinder symmetry) which probably reflects the gas diffusion of oxygen to combustible matter. During co-firing, the enriched silica and alumina components in ZDG efficiently react with the alkali and alkaline earth metals (sodium, magnesium and calcium) in ZDC to form complex minerals, thus effectively capturing and retaining sodium. The slagging and fouling propensity of ashes are notably reduced. Overall, co-firing provides an alternative means to solve the ash slagging and fouling issues, and also for the reduction and resource utilization of coal gangues.

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Investigation of the combustion and ash deposition characteristics of oil palm waste biomasses

Kuswa

Putra

Prabowo

et al. 2023

Biomass Conv. Bioref.

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Biomass serves as an alternative energy solution for decarbonizing coal-fired power plants, which have been reactivated in several countries due to the global energy crisis. Oil palm waste, owing to its abundant availability, holds significant potential as a biomass fuel. This study aimed to investigate the combustion performance of various oil palm wastes in comparison to coal. Biomass combustion is associated with ash-related problems such as slagging, fouling, and corrosion, which may accelerate ash deposit acceleration, reduce heat transfer, and damage refractory equipment in boilers. Ash-related problems were evaluated using the method commonly adopted for solid fuel, including experimental drop tube furnace combustion and ash observation. The results indicate that each oil palm waste has different combustion characteristics. Palm leaves, empty fruit bunch, and palm fronds with clean probe observation have a relatively low tendency of slagging and fouling and can be recommended as biomass fuel for co-firing. However, their high alkali and iron contents need to be considered. Palm fiber has similar combustion characteristics to coal, but it has a high slagging and fouling tendencies. The palm stems with high chlorine content have a high corrosion tendency confirmed by probe observation, scanning electron microscopy, and X-ray diffraction analyses.

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Slagging behavior and mechanism of high-sodium–chlorine coal combustion in a full-scale circulating fluidized bed boiler

Cited by 24 publications

References 35 publications

Computational fluid dynamics modeling of biomass co-firing in a 300 MW pulverized coal furnace

Computational fluid dynamics modeling of biomass co-firing in a 300 MW pulverized coal furnace

Co-Firing Zhundong Coal with Its Gangue: Combustion Performance, Sodium Retention and Ash Fusion Behaviors

Investigation of the combustion and ash deposition characteristics of oil palm waste biomasses

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