Reactivity and Structural Changes of Coal during Its Combustion in a Low-Oxygen Environment

Alvarado, Pedro N.; Cadavid, Francisco; Santamarı́a, Alexander; Ruı́z, Wilson

doi:10.1021/acs.energyfuels.6b01913

Cited by 13 publications

(12 citation statements)

References 47 publications

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“…T d = 210 °C and R = 6.0 were the optimal drying conditions for the COMBD ry drying system, with the maximum C f on the surface of the char obtained from the coal dried under these drying conditions. The total amount of active sites on the particle surface can describe both the oxidation reactivity and the reduction reactivity of a carbonaceous material . Oxygen atoms would attach to vacant C f forming C(O) on particle surface.…”

Section: Resultsmentioning

confidence: 99%

Effects of lignite dewatering treatment on the surface behaviour and NO emission characteristics during the combustion process

Zhao

Sun

et al. 2019

Can J Chem Eng

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Hailaer lignite (HLE) with a uniform particle size distribution (3-6 mm) was employed to investigate the parameters of the low-temperature dewatering process influencing the emission of gaseous pollutants (NO x ) during their combustion process. The combustion of HLE original/dried samples obtained from a COMBD ry drying system were carried out in a fixed bed horizontal furnace under an air atmosphere at the reaction temperature of 1100 8C. The dewatering treatment led to the enhancement of the relative amount of the volatile and fixed carbon content in the upgraded coal sample. The deconvolution of the Raman spectra of each sample showed that the increased degree of drying led to an enhancement of the defects in aromatic structures, indicating an enhancement in the number of active sites or oxygen-containing complexes on particle surface. The devolatilization and combustion experimental results showed the following: (1) with the increase in the degree of drying, more HCN and NH 3 were released during the devolatilization process, and both HCN and NH 3 molecules had positive effects on the consumption of NO under high temperature conditions; (2) due to the enhancement of the specific surface area and total amount of surface active sites (C f ) after the drying treatment, the combustion and reduction reactivity of the dried HLE samples increased significantly; and (3) the conversion ratio of fuel-N to NO during the combustion process decreased significantly with the increase of the degree of dewatering. Therefore, it could be concluded that the removal of moisture content in lignite particles in advance had positive effects on lignite high efficiency combustion with low NO emission.

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Section: Resultsmentioning

confidence: 99%

Effects of lignite dewatering treatment on the surface behaviour and NO emission characteristics during the combustion process

Zhao

Sun

et al. 2019

Can J Chem Eng

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“…A smaller particle size led to a bigger specific area and a larger pore volume and thus a higher reactivity of pulverized coal . Hence, the finer pulverized coal could promote the combustion process with a consequent higher heat generation . On one hand, for the finer pulverized coal, in order to enhance the reduction of NOx, it was necessary to reduce the direct combustion reaction of coal char and O 2 .…”

Section: Resultsmentioning

confidence: 99%

“…36 Hence, the finer pulverized coal could promote the combustion process with a consequent higher heat generation. 37 On one hand, for the finer pulverized coal, in order to enhance the reduction of NOx, it was necessary to reduce the direct combustion reaction of coal char and O 2 . This is the reason that the optimal multihole wall air ratio for the finer pulverized coal was smaller.…”

Section: Energy and Fuelsmentioning

confidence: 99%

Impact of the Multihole Wall Air Coupling with Air Staged on NOx Emission during Pulverized Coal Combustion

Zhou

et al. 2018

Energy Fuels

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Air-staged combustion is one of the most sophisticated and effective technologies for reducing NOx emission during pulverized coal combustion. However, it may also result in problems of high-temperature corrosion, slagging, and highimperfect/incomplete combustion loss. In order to prevent these problems, the multihole wall air coupling with air-staged technology (MH&AS) has been developed. The aim of this work is to investigate the impact of MH&AS on NOx emission by applying a laboratory scale of a MH&AS furnace. The results show that there existed an optimal multihole wall air ratio to significantly reduce the NOx emission. For example, with burner air ratios of 0.6, 0.7, 0.8, and 0.9, the corresponding optimal multihole wall air ratios were 0.100, 0.075, 0.050 and 0.025, respectively. The air distribution mode with a smaller burner air ratio and its optimal multihole wall air ratio were more conducive for NOx reduction. Furthermore, the influence of coal properties on NOx emission was also evaluated. The higher the fuel ratio, the larger the optimal multihole wall air ratio, whereas the finer the pulverized coal, the smaller the optimized multihole wall air ratio. There was a critical moisture content for the specified coal to obtain the minimum of NOx emission. In addition, the effect of MH&AS on the burnout was also explored. The optimal multihole wall air ratio could simultaneously make a minimum amount of NOx emission and the ultimate value of burnout. Finally, the mechanism of NOx reduction by char during MH&AS combustion was proposed.

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“…A Colombian coal extracted from Amagá, Antioquia region, was selected for this study. , We have chosen this coal due to its wide use in electricity generation and local industries such as textile manufacturing or cement factories, in the Antioquia region. In this work, coal sample proximate analysis was determined using the standard method ASTM D7582-15 while ultimate analysis was determined using the standard method ASTM D3176-15.…”

Section: Methodsmentioning

confidence: 99%

Characterization of Coal Combustion in a Hot and Diluted Environment Using a Surface-Stabilized Gas Natural Flame

et al. 2017

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In this study a surface-stabilized flat flame burner has been evaluated for burning pulverized coal samples. The aim of this research was to emulate operating conditions similar to those usually found in moderate or intense low oxygen dilution (MILD) combustion of coal, including high temperature and low oxygen environment. The experimental setup decouples chemical kinetics from complex processes as aerodynamics phenomena. Additionally, it does not require oxygen–nitrogen mixture preparation or electrical heaters. In a first stage, both simulations and experiments were done with natural gas, testing several lean equivalence ratios and unburned gas velocities in the burner to obtain a hot and diluted environment. Then, in a second stage, the coal was suspended at a fixed distance from the burner surface in 4 and 8% v/v oxygen levels. The obtained results show quantitative evolution profiles for CO, CO2, O2, and NO, as well as, N and C releases during the combustion of coal emulating the MILD combustion conditions. This approach is an option for tracking combustion products and physicochemical changes of the solid fuel during reactions, such as those that take place in coal MILD combustion.

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Reactivity and Structural Changes of Coal during Its Combustion in a Low-Oxygen Environment

Cited by 13 publications

References 47 publications

Effects of lignite dewatering treatment on the surface behaviour and NO emission characteristics during the combustion process

Effects of lignite dewatering treatment on the surface behaviour and NO emission characteristics during the combustion process

Impact of the Multihole Wall Air Coupling with Air Staged on NOx Emission during Pulverized Coal Combustion

Characterization of Coal Combustion in a Hot and Diluted Environment Using a Surface-Stabilized Gas Natural Flame

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