CFD modeling of sodium transformation during high-alkali coal combustion in a large-scale circulating fluidized bed boiler

Ji, Jieqiang; Cheng, Leming

doi:10.1016/j.fuel.2020.118447

Cited by 21 publications

(4 citation statements)

References 36 publications

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“…Amoo used standard 𝑘 − 𝜀 model in the CFB boiler simulation, which explains that the error value from the simulation results validated that carried out on experimental data is 10% based on the temperature value in the furnace [21]. RNG 𝑘 − 𝜀 model is used in the CFB boiler simulation by Ji et al, which explains that the error value of the simulation results validation carried out on the experimental data is 8.9% based on the value of the NO gas concentration in the furnace [13].…”

Section: Introductionmentioning

confidence: 94%

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Hydrodynamic Analysis Inside a Circulating Fluidized Bed Boiler Based on Time Change Using CFD

Utomo

Yohana²,

Halim³

et al. 2023

ARFMTS

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The power generation industry has progressively improved the design of power plants to tackle global climate change. Coal-fired power plants will be cleaner and more efficient with the CFB (Circulating Fluidized Bed) technology in the boiler. CFB boilers have the advantage where the resulting carbon dioxide, SOx, and NOx emissions are significantly reduced. This makes research on CFB boilers widely carried out, especially those using CFD (Computational Fluid Dynamic). This study aims to determine the most appropriate turbulence model using CFD simulations on CFB boilers to analyze the hydrodynamic elements in the boiler against time changes, including the distribution of solid volume fractions, pressure, velocity, and wall shear stress. Three turbulence models were tested as part of the simulation: standard , RNG , and RSM, which were then compared to earlier research. The RNG model produces the closest result to the experimental data, with an error value of 6.24%. Solid volume fraction area is increasingly widespread with values ranging from 0.05 to 0.1 from the furnace’s bottom to a height of 15 m. The high-pressure area further expands at the bottom of the furnace to a height of 15 m, with values ranging from 3 kPa to 10 kPa. The outlet line velocity has increased from 43 m/s to 50 m/s. The wall shear stress increases from 0.75 Pa to 1.1 Pa at the outlet wall.

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Section: Introductionmentioning

confidence: 94%

“…Compared to pulverized coal (PC) boilers, it requires a longer ignition time and has unstable combustion at low loads [12]. The combustion/gasification of high alkaline coal in CFB boilers is more beneficial [13]. The furnace temperature in a CFB boiler (approximately 800-900°C) is lower than a PC boiler (approximately 1300-1700°C).…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Analysis Inside a Circulating Fluidized Bed Boiler Based on Time Change Using CFD

Utomo

Yohana²,

Halim³

et al. 2023

ARFMTS

View full text Add to dashboard Cite

show abstract

“…It was verified on a circulating fluidized bed boiler, and a relatively accurate prediction result was obtained. Ji and Cheng [15] used the numerical simulation method to study the ash and slagging problems of high-alkali coal in circulating fluidized bed boilers. The results show that the calculated results of gas-solid flow rate, furnace temperature, and gas type are in good agreement with the measured data.…”

Section: Introductionmentioning

confidence: 99%

Experimental and Numerical Simulation Research on Combustion and NOx Emission of Low Calorific Value and High-Alkaline Coal Based on Jet Characteristics of Flow Field

Qiao

Shen

et al. 2023

International Journal of Energy Research

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A numerical model of a tower boiler burning low calorific value and high-alkali coal was established; based on the jet rigidity of the flow field in the furnace, the effects of air velocity and air volume flow on the combustion of high-alkali coal and NOx emissions were studied. The optimal parameters obtained by numerical simulation are applied to a typical experimental boiler. The experimental results show that when SOFA operates at about 65 m/s, the rigidity of the jet is obviously increased, the flow field and temperature field in the furnace are uniform, the temperature of the flue gas at the outlet is reduced by 53 K, the CO concentration at the furnace outlet was reduced from 3713 ppm to 57 ppm, the exhaust gas temperature was reduced by 6 K, and the concentration of NOx is reduced to 163 mg/m3. On the other hand, the combustion efficiency is increased by 0.86%, which translates into 2 g/kwh of standard coal, and the problem of easy coking has also been effectively solved. The collaborative optimization of high-alkali coal combustion and NOx emission is realized.

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“…[5][6][7] As stated, sodium species tend to volatilize at high temperatures, which can bring about many serious ash-related problems inside reactors. 8 Due to this characteristic, sodium-rich coals have been widely investigated in coal combustion, 9,10 coal pyrolysis, 11,12 and coal gasification for better utilization. 13,14 In addition, sodium-rich coals are also viewed as potential raw materials for direct coal liquefaction (DCL), which is an efficient, clean coal technology.…”

Section: Introductionmentioning

confidence: 99%

Structural changes of Zhundong coal matrix induced by thermal treatment and its effects on oil yield in direct coal liquefaction

Han

2021

Intl J of Energy Research

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Sodium-rich coals are suitable raw materials for direct coal liquefaction (DCL).However, sodium species in coals, especially exchangeable ones, can significantly reduce oil yield. In this work, to increase oil yield in direct liquefaction of sodium-rich coals, a feasible method using organic solvents to pretreat sodium-rich coals is proposed. Initially, sodium-rich coal was thermally treated with tetralin or 1-methylnaphtalene. Then, raw coal and all the treated coals were liquefied under the same conditions to evaluate the effects of thermal treatment on structural changes of coal molecules and oil yield. The results show that surface areas of the treated coals increased to 7.86 m 2 /g at most, which was favorable for combination between hydrogen and coal molecules during the DCL process. More importantly, the content of hydrogen in the treated coals was 0.95 wt% higher than that of raw coal on average, suggesting that treated coals could be later liquefied at mild conditions. Raman spectra demonstrated that during thermal treatment with tetralin, small aromatic ring systems in raw coal were prehydrogenated and transformed into nonaromatic systems. The pre-hydrogenation of the coal matrix definitely contributes to the increase in oil yield. In view of sodium species distribution in the treated coals, it is proved that tetralin can promote the transformation of exchangeable sodium species into other chemical forms more easily than 1-methylnaphtalene, which implies that tetralin has more positive effects on the increase of oil yield. Compared with that of raw coal, oil yields in direct liquefaction of the samples treated by tetralin increase by 14.0 to 15.1 wt% (daf).

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CFD modeling of sodium transformation during high-alkali coal combustion in a large-scale circulating fluidized bed boiler

Cited by 21 publications

References 36 publications

Hydrodynamic Analysis Inside a Circulating Fluidized Bed Boiler Based on Time Change Using CFD

Hydrodynamic Analysis Inside a Circulating Fluidized Bed Boiler Based on Time Change Using CFD

Experimental and Numerical Simulation Research on Combustion and NOx Emission of Low Calorific Value and High-Alkaline Coal Based on Jet Characteristics of Flow Field

Structural changes of Zhundong coal matrix induced by thermal treatment and its effects on oil yield in direct coal liquefaction

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