Numerical simulation study on the influences of the secondary-tertiary air proportion on the airflow mixing effects and pulverized coal combustion characteristics in a 300-MW down-fired boiler

Li, Xiaoguang; Zeng, Lingyan; Liu, Hongye; Du, Hejun; Yang, Xiuchao; Han, Hu; Liu, Wenjie; Zhang, Shaofeng; Song, Ming; Chen, Zhichao; Li, Zhengqi

doi:10.1016/j.psep.2019.08.022

Cited by 7 publications

(4 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The NO concentrations of the fuel and the oxygen level in the combustion zone both affect how much NO is produced. Further, sufficient oxygen allows full combustion of the fuel [24]. Volatile fraction of NO conversion increases with the increasing oxygen concentration.…”

Section: Impact Factormentioning

confidence: 99%

Effects of co-disposal of sludge based on TTF-type precalciner on NOx emissions

Ruru Liang,

Guanglei Yuan,

Renping Liu

et al. 2023

Environ. Protect. Eng.

View full text Add to dashboard Cite

To reduce the emission of nitrogen oxides (NOx) during the co-disposal of sludge in a TTF-type precalciner, an optimized co-disposal process of a TTF-type precalciner has been implemented in a cement plant in Hebei. The model was built using ANSYS FLUENT software. The effects of three singlefactor perspectives (sludge input ratio, gas flow rate, and tertiary air temperature on NO concentration) were investigated. The response surface method of Box-Behnken design was used. When the sludge ratio increased from 0 to 25%, the NO concentration at the outlet was 122-297 mg/m³. Meanwhile, it increased from 192 mg/m³ to 241 mg/m³ since the airflow increased from 95 m³/s to 122 m³/s. The maximum NO concentration was 192 mg/m³ when the tertiary air temperature was 1170 K. The interaction between airflow and sludge ratio was more significant than any other interaction between other conditions (P < 0.05). Finally, the optimum conditions were a sludge ratio of 5%, airflow 109 m³/s, and tertiary air temperature 1280 K. NO concentration was 166.9 mg/m³ under this condition.

show abstract

Section: Impact Factormentioning

confidence: 99%

Effects of co-disposal of sludge based on TTF-type precalciner on NOx emissions

Ruru Liang,

Guanglei Yuan,

Renping Liu

et al. 2023

Environ. Protect. Eng.

View full text Add to dashboard Cite

show abstract

“…It can be observed that the temperature level was lower and more homogeneous at a lower secondary air ratio on the arch. At the condition of a lower secondary air ratio on the arch, the cooling effect can be weakened and the combustion of char and volatiles can be relatively slowly burnt along the pathway [12]. Therefore, the temperature profile was more homogeneous.…”

Section: The Air Distribution Of F-layer and Archmentioning

confidence: 99%

“…There have been extensive studies on new technology for the NOx control of downfired boilers [7][8][9][10][11][12][13][14][15][16]. A stronger reductive atmosphere in the lower zone of the furnace, a larger circulation area near coal/air injection nozzles, a longer residence time of coal particles within a furnace and a proper temperature distribution are essential for the above purpose.…”

Section: Introductionmentioning

confidence: 99%

“…It was also found that the preferred position of the coal-lean stream was in the front and rear walls in the lower zone of the furnace and a declination of 20 • for secondary air showed the best performance. Li et al [12] studied the effect of the ratio of secondary air and coal-lean stream on the combustion characteristics of a 300 MW down-fired boiler. The result revealed that the ignition distance was reduced from 1.30 to 0.84 m when the secondary air ratio increased from 30.5% to 42.5%.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Retrofit of a 600 MW Down-Fired Pulverized-Coal Furnace for Low NOx Emission

Liu,

Wang,

Wei

et al. 2023

Energies

View full text Add to dashboard Cite

Aiming at solving the problem of high NOx emissions of a down-fired boiler, a new combustion system has been proposed by means of the numerical simulation using Ansys Fluent. The coal-lean stream (tertiary air), which was originally mixed with a separated overfired air (SOFA) stream on the front and rear walls of the upper furnace, was relocated to the lower zone of the furnace after retrofit. The secondary-air slots were transformed into a new annular port type, which was injected into the furnace with a down-tilt angle to increase the residence time of the coal stream. Furthermore, the effect of secondary air distribution and velocity of coal stream on performance was studied. After retrofitting the combustion system, the NO emissions were effectively controlled, decreasing from 906 mg Nm−3 to 576 mg Nm−3, but the carbon content of fly ash increased from 2.46% to 5.78%. Aiming at decreasing the carbon content of fly ash, the effect of coal/primary air velocity on the arch was studied. Less carbon content in fly ash can be observed for the lower arch airflow velocity. The results showed that the NO emissions can be controlled below 595 mg Nm−3, and the carbon content of fly ash was reduced to 3.39% when the velocity was decreased to 18 m s−1.

show abstract