Numerical evaluation of pulverized coal swirling flames and NOx emissions in a coal-fired boiler: Effects of co- and counter-swirling flames and coal injection modes

Choi, Muhan; Park, Yeseul; Li, Xinzhuo; Kim, Kibeom; Sung, Youl-Moon; Hwang, Taegam; Choi, Gyung‐Min

doi:10.1016/j.energy.2020.119439

Cited by 25 publications

(7 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is because the higher the velocity of arch airflow, the more pulverized coal can penetrate deep into the lower position of the furnace and form more CO. At around 20 m, a higher CO concentration can be observed for a lower arch airflow. At a lower arch airflow velocity, more of the coal-particle stream can be burnt near the nozzle, thus creating a stronger reductive atmosphere, showing a better effect on suppressing NO formation [34]. Upon injecting the SOFA into the upper zone of the furnace, the oxygen concentration increased markedly and a final higher oxygen emission could be observed for a higher velocity of arch airflow.…”

Section: The Influence Of Velocity Of Arch Airflowmentioning

confidence: 99%

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

Section: The Influence Of Velocity Of Arch Airflowmentioning

confidence: 99%

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

show abstract

“…Therefore, regardless of boiler type and capacity, combustion control is important for energy saving, combustion efficiency and low emission [1,2]. The combustion instability phenomenon has been encountered in many combustion processes such as power plants [3], cement production [4], * Author to whom any correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Flame stability measurement through image moments and texture analysis

Golgiyaz¹,

Cellek²,

Daskin³

et al. 2023

Meas. Sci. Technol.

View full text Add to dashboard Cite

In this article, the first two moments of the image, mean and standard deviation, uniform Local Binary Pattern (LBP) texture analysis methods were experimentally investigated in coal-fired boilers to measure flame stability. The first two moments of the flame image were used to evaluate the flame stability in terms of color and brightness (average gray value). Although the radiation signal of the flame is widely obtained by the spectral analysis method, the radiation signal of the flame was obtained by the LBP texture analysis method in this study. The flame stability measurement technique proposed in this study does not require prior knowledge about CCD camera features. Therefore, it can be easily applied to measure flame stability without expensive and complicated adaptation processes. Flame stability was measured with R = 0.9868 accuracy with the proposed method. The experimental results show that the proposed texture analysis method is more effective than current spectral analysis methods. The results obtained within the scope of this study also show that it can be easily applied to existing closed-loop control systems to monitor flame stability.

show abstract

“…According to the global emission reduction goal (moving toward the NZE), the reduction of NOx emissions in the power sector using solid fuel was limits of 200 mg/m 3 for above 50 MW th ,2 . Currently, numerous technologies, including low-NOx burners, , air or fuel staging combustion, over-fire air (OFA) operation, , flue gas reburning, or recirculation, are used to control NOx emissions. These technologies are used to minimize nitrogen contact with fuel and oxygen while permitting NOx reduction in fuel-rich zones.…”

Section: Introductionmentioning

confidence: 99%

Numerical Optimization on Char Conversion and NOx Emission under Various Operating Conditions in a Retrofit Biomass Boiler

et al. 2023

View full text Add to dashboard Cite

Retrofitting retirement or existing fossil boiler with biomass is an important method of curbing electricity shortage and lowering the cost of modern power plants. However, the use of biomass combustion is hampered by operational problems, such as the resulting high unburned carbon, amount of bottom ash, and nitrogen oxide (NOx) release. In this study, we investigated the burning of pulverized biomass in a retrofitting boiler power plant using computational fluid dynamics of commercial software fluent ANSYS to determine the optimal combustion conditions. The objective of this study was to investigate a 125 MWe pulverized biomass boiler that was retrofitted from an anthracite down-fired boiler. The air distribution, including the influence of the secondary air ratio and the location of the burner standby, was evaluated. Key factors such as biomass ash mass at the hopper, char conversion, and high zone temperature relating to NOx formation/reduction were calculated. The adjustment of the secondary air ratio from 30 to 50% of the total air and the mass ash at the hopper significantly decreased to a low value at 247 kg/h and a high value of char conversion at 97.33% in case R (SA40%). The standard deviation temperature was 240 K at the BNR B−A level for case R, which was significantly lower than in other cases. This implies that the best mixing of air and biomass occurs in case R at 40%. Comparative analysis of the burner standby conditions showed that the NOx emission was similar at the boiler outlet (approximately 94−116 ppm). Burner A on standby, with a secondary air ratio of 40%, was used as the optimal case with the highest value of char conversion at 98.43%, the lowest bottom ash release of 204 kg/h, and a low-NOx emission of 106 ppm.

show abstract

Numerical evaluation of pulverized coal swirling flames and NOx emissions in a coal-fired boiler: Effects of co- and counter-swirling flames and coal injection modes

Cited by 25 publications

References 59 publications

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

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

Flame stability measurement through image moments and texture analysis

Numerical Optimization on Char Conversion and NOx Emission under Various Operating Conditions in a Retrofit Biomass Boiler

Contact Info

Product

Resources

About