Investigation and Control Technology on Excessive Ammonia-Slipping in Coal-Fired Plants

Xuan, Yi; Zhang, Man; Kong, Hao; Lyu, Junfu; Yang, Hairui

doi:10.3390/en13164249

Cited by 9 publications

(5 citation statements)

References 31 publications

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“…The NH 3 /NO X ratio in the SCR system is a critical factor affecting denitrification efficiency [ 62 ]. Considering that the ratio of NH 3 /NO X should range from 0.8 to 1.2 for the effective removal of NOx in stationary, the selective oxidation reaction of ammonia in the NH 3 -SCR system of the synthesized catalysts was NH 3 /NO X .…”

Section: Resultsmentioning

confidence: 99%

High-Dispersed V2O5-CuOX Nanoparticles on h-BN in NH3-SCR and NH3-SCO Performance

Lee

Kim

et al. 2022

Nanomaterials

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Typically, to meet emission regulations, the selective catalytic reduction of NOX with NH3 (NH3-SCR) technology cause NH3 emissions owing to high NH3/NOX ratios to meet emission regulations. In this study, V-Cu/BN-Ti was used to remove residual NOX and NH3. Catalysts were evaluated for selective catalytic oxidation of NH3 (NH3-SCO) in the NH3-SCR reaction at 200–300 °C. The addition of vanadium and copper increased the number of Brønsted and Lewis acid sites available for the reaction by increasing the ratio of V5+ and forming Cu+ species, respectively. Furthermore, h-BN was dispersed in the catalyst to improve the content of vanadium and copper species on the surface. NH3 and NOX conversion were 98% and 91% at 260 °C, respectively. Consequently, slipped NH3 (NH3-Slip) emitted only 2% of the injected ammonia. Under SO2 conditions, based on the NH3 oxidation reaction, catalytic deactivation was improved by addition of h-BN. This study suggests that h-BN is a potential catalyst that can help remove residual NOX and meet NH3 emission regulations when placed at the bottom of the SCR catalyst layer in coal-fired power plants.

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Section: Resultsmentioning

confidence: 99%

High-Dispersed V2O5-CuOX Nanoparticles on h-BN in NH3-SCR and NH3-SCO Performance

Lee

Kim

et al. 2022

Nanomaterials

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“…The principle of SCR denitrification is to convert NO x in flue gas into non-toxic and harmless N 2 and H 2 O using NH 3 or urea as a reductant with the help of the catalyst and within the suitable temperature zone (573-693 K) [3,4]. But, the issue of ammonia escape can occur because of catalyst aging, catalyst poisoning, temperature changes, or an excessive amount of ammonia injected into the SCR denitrification system [2,5]. A small portion of SO 2 in the flue gas can be oxidized to SO 3 by the catalyst during the process of the flue gas denitrification [6,7]; meanwhile, the generation of SO 3 can be promoted by NO Energies 2023, 16, 6513 2 of 17 and NH 3 in the flue gas [8].…”

Section: Introductionmentioning

confidence: 99%

Laboratory Study on Adhesive Ash Deposition Characteristics of Ammonium Bisulfate in Conditions Simulating an Air Preheater for Hard Coal Combustion

Chen,

Ji,

Feng

et al. 2023

Energies

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The ash blockage of the rotary air preheater is a serious problem of the coal-fired boiler that urgently needs to be solved, which is caused by the adhesive deposition of ammonium bisulfate (ABS) and the fly ash. A comprehensive experimental study was performed to investigate the adhesive ash deposition characteristics based on an experimental platform established. The influences of the gas temperature, the gas velocity, the mass ratio of the ABS to the fly ash (R), and the ash particle size on the ash deposition characteristics were mainly analyzed and discussed under different conditions. The experimental results indicate that the liquid ABS is the root cause of the ash particles adhering to the heat transfer elements of the air preheater. The experimental results indicate that when the gas temperature is in the range of 420–493 K, the ABS ash deposition intensity and the ABS adhesion rate both increase with the increase in the gas temperature. When it is 493 K, the ABS adhesion rates of the corrugated plate and the positioning plate both reach maximum values, which are 31.7% and 27.9%, respectively. With the decrease in gas velocity, the total ash deposition intensity, the ABS ash deposition intensity, the ABS adhesion rate, and the growth rate of the ABS adhesion all increase. The content of ABS in the fly ash is also an important factor. When R rises, the ash deposition intensity and the ABS adhesion rate increase significantly. The particle size of the fly ash has little influence on the total ash deposition intensity, but has a great influence on the ABS ash deposition intensity and the ABS adhesion rate. With the increase in the particle size in the range of 30.8–100 μm, the ABS ash deposition intensity decreases by nearly 50%, and the ABS adhesion rates of plates A and B decrease by about 43.9% and 49.6%, respectively. According to the study results, some effective measures can be taken to solve the ash blocking problem of the rotary air preheater, including using the steam air heater, optimizing the operation parameters of the soot blower, and inhibiting ABS formation.

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“…Many scholars have expanded the SNCR technology to high temperature region. Yao et al [3] investigated and analyzed the current situation of ammonia injection denitrification technology and ammonia pollution in coal-fired power plants in China. Fan et al [4] experimentally studied the effect of ammonia solution and its metal additive solution (Fe 2 O 3 , Fe 3 O 4 , CuO, Cu 2 O, MnO, etc.)…”

Section: Introductionmentioning

confidence: 99%

Computational modeling of flow field in boiler before and after urea injection under different conditions

Zhuo

Zeng

2021

THERM SCI

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In order to achieve ultra-low NOx emissions, the effects of total excess air coefficient, air coefficient in main combustion zone, blended-coal combustion and ammonia nitrogen molar ratio on a 330 MW coal-fired boiler combustion were studied by numerical simulation. The results show that the velocity field and temperature field in the furnace have synergy, the better the synergy is, the faster the temperature rises, and the more NOx it generates. Compared before and after urea spraying, the NOx concentration decreased with the decrease of the total excess air coefficient, the optimum total excess air coefficient is about 1.15, and the denitrification rate is as high as 76.2%. The smaller the air coefficient in the main combustion zone is, the smaller the NOx concentration is. The optimum air coefficient in the main combustion zone is about 0.92, and the denitrification rate is 85%. After urea injection, the denitrification rate of high volatile coal combustion is higher than that of low volatile coal combustion, and the reasonable blending mode of coal can reduce NOx emissions. The larger the ammonia-nitrogen molar ratio is, the lower the NOx concentration is. When the ammonia-nitrogen molar ratio is greater than 2, the amount of ammonia escape at the flue outlet exceeds the standard. When the ammonia-nitrogen molar ratio is less than 1, the NOx concentration at the flue outlet is greater than that before urea injection. The optimal ammonia-nitrogen molar ratio is about 2.

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Investigation and Control Technology on Excessive Ammonia-Slipping in Coal-Fired Plants

Cited by 9 publications

References 31 publications

High-Dispersed V2O5-CuOX Nanoparticles on h-BN in NH3-SCR and NH3-SCO Performance

High-Dispersed V2O5-CuOX Nanoparticles on h-BN in NH3-SCR and NH3-SCO Performance

Laboratory Study on Adhesive Ash Deposition Characteristics of Ammonium Bisulfate in Conditions Simulating an Air Preheater for Hard Coal Combustion

Computational modeling of flow field in boiler before and after urea injection under different conditions

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