Nitric oxide (NO) and nitrous oxide (N2O) emissions during selective non-catalytic reduction and selective catalytic reduction processes in a pulverized coal/Ammonia Co-fired boiler

Jeon, MinKyu; Lee, Eunsong; Kim, Minsu; Jegal, Hyunwook; Park, Sangbin; Hwa, Jun; Baek, Sehyun; Lee, Jongmin; Keel, Sang-In

doi:10.1016/j.jece.2023.109398

Cited by 19 publications

(4 citation statements)

References 23 publications

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“… 35 Simultaneously, ammonia radicals began to decompose in the early stages of combustion, so there were more ammonia radical decompositions when the coal concentration was lower, which facilitated the generation of NO 2 . The OH radicals were produced by the decomposition of water vapor in the flue gas after ammonia combustion also promoted the conversion of N 2 O to NO 2 , 36 as shown in eq 17 . When HAB = 100 mm, the nitrogen in the fuel was mainly converted to NO and the content of NO 2 was relatively low.…”

Section: Resultsmentioning

confidence: 99%

Experimental Study on Flame Chemical Composition of Coal and Ammonia Gas–Solid Jet in Flat Flame Burner

Cui,

Niu,

et al. 2024

ACS Omega

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Ammonia as a fuel to partially or completely replace fossil fuels is one of the effective ways to reduce carbon dioxide, and the research on ammonia coal cocombustion is of great significance. The combustion characteristics of ammonia are very different from those of pulverized coal, resulting in the ignition and emission characteristics of ammonia and pulverized coal gas flow that is different from traditional pulverized coal flame. In this paper, the effect of pulverized coal concentration in coal and ammonia mixed combustion jet on the ignition distance and gas-phase components at different positions of the jet flame were studied experimentally on the flat flame burner, and the conditions of ignition and ignition stability of coal and ammonia gas−solid fuel were expounded. It was found that the ammonia mixed with pulverized coal changed the temperature field of the flat flame burner and therefore the ignition characteristics of the jet were changed. The ignition delay time at the same jet speed was positively correlated with the pulverized coal concentration, but when the pulverized coal concentration continued to decrease, the influence on the ignition delay time gradually became smaller. The composition of coal ammonia gas−solid fuel changed the heat transfer path and share during combustion, and finally, the flame temperature was negatively correlated with the concentration of pulverized coal. Therefore, the reduction of the pulverized coal concentration was conducive to the stable combustion of coal ammonia mixed fuel. When HAB = 100 mm, the conversion rate of fuel N to NO x per unit mass of coal ammonia mixture increased with the increase of pulverized coal concentration. The NO x production amount first increased and then decreased with the increase of pulverized coal concentration, and the amount of N 2 O and NO 2 decreased rapidly with the increase of HAB. The proportion of NO x in NO exceeded 94%, which was conducive to achieving low nitrogen combustion of coal and ammonia gas−solid fuel. In general, the O 2 concentration in the ammonia coal jet flame decreased, the flue gas temperature, and NO x and CO generation increased after mixing ammonia, and the optimal pulverized coal concentration in this experiment was 0.41 kgc/kga (mass ratio of pulverized coal to the sum of N 2 and NH 3 ).

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Section: Resultsmentioning

confidence: 99%

Experimental Study on Flame Chemical Composition of Coal and Ammonia Gas–Solid Jet in Flat Flame Burner

Cui,

Niu,

et al. 2024

ACS Omega

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“…x i (10) where C v is the coefficient of standard deviation; σ is the standard deviation; x is the average value (m/s); i is the number for each point; and n is the total number of measuring points.…”

Section: Scr Reaction Mechanism and Evaluation Method-indexing (Evenn...mentioning

confidence: 99%

“…At present, the technologies used for NO x control overseas mainly include low-carbon combustion technology, selective catalytic reduction (SCR) technology, and non-selective catalytic reduction (SNCR) process [10][11][12]. Owing to its technological maturity and high deNO x efficiency, SCR technology is widely used in domestic captive power plants [13,14].…”

Section: Introductionmentioning

confidence: 99%

Design and Verification of Key Components of a New Selective Catalytic Reduction System in a Petrochemical Captive Power Plant

Wu,

Liu,

Zhang

et al. 2023

Processes

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A new selective catalytic reduction (SCR) system for captive power plants in the petrochemical industry was analyzed. The key components suitable for the target SCR system were obtained using computational fluid dynamics (CFD) numerical simulation combined with a cold physical model. The structural characteristics of the SCR system were studied, and corresponding design schemes were obtained for the key components, such as the guide plate, the ammonia injection grid (AIG), the static mixer, and the rectifier grille. The distributions of the flue gas velocity and the NH3 concentration within the flue cross-section in front of the first layer catalyst were studied in detail. Synchronously, the pressure loss and the temperature reduction characteristics in the SCR system were also considered. CFD results showed that the average standard deviation of the flue gas velocity was about 11.61%, and the average standard deviation of the NH3 concentration distribution could reach about 3.79% under the five operating conditions. It could be concluded that the uniformity of the flue gas velocity and the NH3 concentration distribution within the above flue cross-section was guaranteed by comparing to the design standard of 15% and 5%, respectively. It was further found that the maximum pressure loss between the inlet and the first layer catalyst was about 106.64 Pa, and the temperature reduction characteristic of the entire SCR system could be maintained within ±0.01 °C, which indicated that no extreme adverse effect arose due to the introduce of the key components. The cold physical model experiment was accordingly conducted to verify the reliability of the above CFD results. The cold physical model experiment results showed that the average standard deviation of flue gas velocity was about 8.82%, and the average standard deviation of NH3 concentration distribution could reach about 4.21%. The maximum biases for the standard deviations of the flue gas velocity and the NH3 concentration distribution were approximately 4.83% and 1.18% under the five operating conditions. Based on the good agreement of the research results via the two different methods, the designed key components of a new SCR system could be confirmed to be feasible, which would benefit the deNOx performance of the SCR system.

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“…One of the characteristics of low-rank coal itself is that it has a relatively high volatile content of over 20%, and this is why low-rank coal is easier to use in terms of realizing stable combustion, even with a low load condition. However, the problem is that the NO x formation amount is still in the range of 300-600 mg/m 3 , even given the use of elements of advanced low-NO x combustion technology such as air-staging, flue gas recirculation, and a low-NO x burner [2][3][4], resulting in the increase of de-nitration costs to meet the pollutant emission standards. For instance, in China, the NO x emission limitation is 50 mg/m 3 for coal-firing power plants, making it the strictest emission standard in the world.…”

Section: Introductionmentioning

confidence: 99%

Experimental Studies on Preheating Combustion Characteristics of Low-Rank Coal with Different Particle Sizes and Kinetic Simulation of Nitrogen Oxide

Zhang,

Zhu,

Liu

2023

Energies

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Low-rank coal, accounting for 45% of the global coal reserves, is easier to use in terms of realizing ignition and stable combustion due to its relatively high levels of volatile content. But the problem of low-rank coal combustion is that its NO formation is in the range of 300–600 mg/m3, which makes the emission’s meeting of the environmental regulation quite difficult or uneconomic. Preheating combustion was a prospective combustion technology which involved preheating in a circulating fluidized bed (CFB) first and then combustion in a combustor for preheated fuel. With three particle sizes (0–0.355 mm, 0–0.5 mm, and 0–1 mm), some experiments were carried out in a 30 kW test rig. The results showed that, in the CFB preheating, a particle size of 0–1 mm had the highest coal-gas heating value due to a long residence time. The release of species in the CFB preheating always followed the order H > N > C > S. For preheated fuel combustion, a particle size of 0–0.355 mm showed the fastest combustion velocity, with the highest temperature point near the nozzle. For all three particle sizes, the combustion of preheated fuel showed a uniform temperature distribution with a small temperature difference. The lowest NO emission was 105 mg/m3 for the particle size of 0–0.5 mm. A GRI-Mech 2.11 mechanism was used to simulate the formation of NO with different influencing factors, such as temperature, oxygen concentration, and secondary-air ratio. There was a good agreement between the experimental data and the simulation’s results. The simulation showed that the NO formation could be further decreased with an optimal secondary-air ratio. This investigation provides support for the basic understanding of preheating-combustion technology and potential industrial applications in the future.

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Nitric oxide (NO) and nitrous oxide (N2O) emissions during selective non-catalytic reduction and selective catalytic reduction processes in a pulverized coal/Ammonia Co-fired boiler

Cited by 19 publications

References 23 publications

Experimental Study on Flame Chemical Composition of Coal and Ammonia Gas–Solid Jet in Flat Flame Burner

Experimental Study on Flame Chemical Composition of Coal and Ammonia Gas–Solid Jet in Flat Flame Burner

Design and Verification of Key Components of a New Selective Catalytic Reduction System in a Petrochemical Captive Power Plant

Experimental Studies on Preheating Combustion Characteristics of Low-Rank Coal with Different Particle Sizes and Kinetic Simulation of Nitrogen Oxide

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