Experimental Investigation of Nitrogen Species Distribution in Wood Combustion and Their Influence on NOx Reduction by Combining Air Staging and Ammonia Injection

The use of separated overfire air (SOFA) has become a standard technique of air staging for NOx reduction in the coal-fired boiler and can also be applied to existing boilers by retrofit. This study was to optimize the air distribution for the proposed SOFA installation in a 500 MWe tangential-firing boiler that has 20 identical units in Korea. Using computational fluid dynamics (CFD) incorporating advanced coal combustion submodels, the reference case was established in good agreement with the design data, and different flow ratios of burner secondary air, close-coupled OFA (CCOFA), and SOFA were evaluated. Increasing the total OFA ratio effectively suppressed NO formation within the burner zone but had a negative impact on the boiler performance. With moderate air staging, NO reduction became active between the CCOFA and SOFA levels and, therefore, the OFA distribution could be optimized for the overall boiler performance. For total OFA ratios of 25% and 30% with respective burner zone stoichiometric ratios of 0.847 and 0.791, increasing the SOFA ratio to 15% and 20%, respectively, was ideal for decreasing the unburned carbon release and ash slagging as well as NO emission. Too high or low SOFA ratios rapidly increased the unburned carbon because of inefficient mixing between the strong air jets and char particles. Based on these ideal cases, the actual air distribution can be adjusted depending on the coal properties such as the ash slagging propensity.

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Experimental Investigation on NOx Reduction Potential of Gas-Fired Coal Preheating Technology

Energy & Fuels ◽

10.1021/ef501175v ◽

2014 ◽

Vol 28 (9) ◽

pp. 6089-6097 ◽

Cited By ~ 7

Author(s):

Changchun Liu ◽

Shien Hui ◽

Su Pan ◽

Hao Zou ◽

Geng Zhang ◽

...

Keyword(s):

Experimental Investigation ◽

Reduction Potential ◽

Nox Reduction

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An Experimental Investigation of Wood Combustion

Journal of Energy Resources Technology ◽

10.1115/1.2906442 ◽

1994 ◽

Vol 116 (3) ◽

pp. 186-193 ◽

Cited By ~ 2

Author(s):

A. Dadkhah-Nikoo ◽

D. J. Bushnell

Keyword(s):

Experimental Investigation ◽

Particle Size ◽

Moisture Content ◽

Combustion Products ◽

Combustion Efficiency ◽

Particulate Emissions ◽

Fuel Particle ◽

Wood Combustion ◽

Part Load ◽

Excess Air

This paper presents the results from an experimental investigation of wood combustion. Variables chosen for investigation are fuel moisture content, fuel particle size, excess air, fraction and temperature of under-fire air. Influence of the off-design (part load) operation of the combustion unit on combustion efficiency and particulate emission is also investigated. Data recorded during the experiments include the composition and temperature of the combustion products, particulate emissions, and combustible fraction of the particulate. Based on the experimental data, a linear regression model was developed to investigate the variables affecting the combustion process. A computer model was used to calculate the temperature and composition of the combustion products under adiabatic conditions. Results of the adiabatic model and the experimental regression analysis are compared and discussed. According to the results presented, it is concluded that the combustion efficiency and particulate emissions are most influenced by the factors that increase the volume of the combustion products in the combustion chamber. These variables include excess air, moisture content of the fuel, and the combustion air temperature. Fuel particle size and the fraction of under-fire air did not significantly affect the combustion efficiency and particulate emissions. It is also concluded that the off-design (part-load) operation of the combustion unit, results in higher particulate emissions and lower combustion efficiency.

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Experimental investigation on water treatment by the combined nano MgO–nanofiltration technique

Water Science & Technology ◽

10.2166/wst.2011.510 ◽

2011 ◽

Vol 63 (11) ◽

pp. 2542-2546 ◽

Cited By ~ 5

Author(s):

Keqiang Zhang ◽

Yi An ◽

Feng Wang ◽

Lingling Lin ◽

Haigang Guo

Keyword(s):

Heavy Metals ◽

Experimental Investigation ◽

Water Treatment ◽

Suspended Solids ◽

Pollutant Removal ◽

Polluted Water ◽

Operating Pressure ◽

Nitrogen Species ◽

Combined System ◽

Mg Content

A combined system using nano MgO and nanofiltration (NF) membrane was established to purify polluted water in this experiment. The turbidity, permanganate index, UVA254, colony counts and the concentrations of NO3−, NO2−, NH4+, Fe, Mn and Mg of the effluents from each unit of this combined system were measured to investigate the pollutant removal of this system. Based on the results obtained, the combined nano MgO–NF system could efficiently remove many kinds of pollutants in this experiment, including organic matter, nitrogen species, heavy metals, suspended solids and bacteria. And the effluents could meet the standard of drinking water. Furthermore, increasing the nano MgO dosage could not elevate the removal ratio of the pollutants, but only increase the Mg content of the effluent. Thus, 0.05 g L−1 of nano MgO may be a suitable dosage for 2,000 L of polluted water treatment. Also, the operating pressure of NF membrane had no significant effect on pollutant removal when the operating pressure of NF membrane was increased from 0.3 to 0.9 MPa.

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NOx Reduction in Partially Premixed Flames by Flue Gas Recirculation

Volume 8B: Heat Transfer and Thermal Engineering ◽

10.1115/imece2014-39367 ◽

2014 ◽

Author(s):

Yaroslav Chudnovsky ◽

Serguei Zelepouga ◽

Alexei Saveliev ◽

John Wagner ◽

Vitaly Gnatenko

Keyword(s):

Experimental Investigation ◽

Flue Gas ◽

Nox Reduction ◽

Premixed Flames ◽

Combustion System ◽

Flue Gas Recirculation ◽

Partially Premixed Flames ◽

Partially Premixed ◽

Burner Operation ◽

Gas Recirculation

The authors are currently investigating new technical (both design and operation) approach, which is expected to enable the improvement of the performance of partially premixed type burners without jeopardizing the simplicity, cost, and reliability that this type of burners are well known for. The improvements include significant reduction of the NOx emission without substantial redesign of the combustion system. The results of the experimental investigation of burner operation and design improvements are to be presented and further discussed at the podium.

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