Modeling of pulverized coal combustion for in-furnace NOx reduction and flame control

A cost-effective reduction of NOx emission from utility boilers firing pulverized coal can be achieved by means of combustion modifications in the furnace. It is also essential to provide the pulverized coal diffusion flame control. Mathematical modeling is regularly used for analysis and optimization of complex turbulent reactive flows and mutually dependent processes in coal combustion furnaces. In the numerical study, predictions were performed by an in-house developed comprehensive three-dimensional differential model of flow, combustion and heat/mass transfer with submodel of the fuel- and thermal-NO formation/ destruction reactions. Influence of various operating conditions in the case-study utility boiler tangentially fired furnace, such as distribution of both the fuel and the combustion air over the burners and tiers, fuel-bound nitrogen content and grinding fineness of coal were investigated individually and in combination. Mechanisms of NO formation and depletion were found to be strongly affected by flow, temperature and gas mixture components concentration fields. Proper modifications of combustion process can provide more than 30% of the NOx emission abatement, approaching the corresponding emission limits, with simultaneous control of the flame geometry and position within the furnace. This kind of complex numerical experiments provides conditions for improvements of the power plant furnaces exploitation, with respect to high efficiency, operation flexibility and low emission.

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Numerical study of pulverized coal-fired utility boiler over a wide range of operating conditions for in-furnace SO2/NOx reduction

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2015.10.162 ◽

2016 ◽

Vol 94 ◽

pp. 657-669 ◽

Cited By ~ 30

Author(s):

Srdjan Belošević ◽

Ivan Tomanović ◽

Nenad Crnomarković ◽

Aleksandar Milićević ◽

Dragan Tucaković

Keyword(s):

Numerical Study ◽

Nox Reduction ◽

Pulverized Coal ◽

Operating Conditions ◽

Utility Boiler ◽

Wide Range

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Modeling and optimization of processes for clean and efficient pulverized coal combustion in utility boilers

Thermal Science ◽

10.2298/tsci150604223b ◽

2016 ◽

Vol 20 (suppl. 1) ◽

pp. 183-196 ◽

Cited By ~ 3

Author(s):

Srdjan Belosevic ◽

Ivan Tomanovic ◽

Nenad Crnomarkovic ◽

Aleksandar Milicevic ◽

Dragan Tucakovic

Keyword(s):

Emission Reduction ◽

Power Plants ◽

Position Control ◽

Process Analysis ◽

Combustion Process ◽

Pulverized Coal ◽

Operating Conditions ◽

Nox Emission ◽

Boiler Furnace ◽

Boiler Units

Pulverized coal-fired power plants should provide higher efficiency of energy conversion, flexibility in terms of boiler loads and fuel characteristics and emission reduction of pollutants like nitrogen oxides. Modification of combustion process is a cost-effective technology for NOx control. For optimization of complex processes, such as turbulent reactive flow in coal-fired furnaces, mathematical modeling is regularly used. The NOx emission reduction by combustion modifications in the 350 MWe Kostolac B boiler furnace, tangentially fired by pulverized Serbian lignite, is investigated in the paper. Numerical experiments were done by an in-house developed three-dimensional differential comprehensive combustion code, with fuel- and thermal-NO formation/destruction reactions model. The code was developed to be easily used by engineering staff for process analysis in boiler units. A broad range of operating conditions was examined, such as fuel and preheated air distribution over the burners and tiers, operation mode of the burners, grinding fineness and quality of coal, boiler loads, cold air ingress, recirculation of flue gases, water-walls ash deposition and combined effect of different parameters. The predictions show that the NOx emission reduction of up to 30% can be achieved by a proper combustion organization in the case-study furnace, with the flame position control. Impact of combustion modifications on the boiler operation was evaluated by the boiler thermal calculations suggesting that the facility was to be controlled within narrow limits of operation parameters. Such a complex approach to pollutants control enables evaluating alternative solutions to achieve efficient and low emission operation of utility boiler units.

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NUMERICAL SIMULATION ON PULVERIZED COAL COMBUSTION PROCESS IN A TANGENTIAL FIRING FURNACE

Journal of Mechanical Engineering ◽

10.3901/jme.2006.08.107 ◽

2006 ◽

Vol 42 (08) ◽

pp. 107 ◽

Cited By ~ 3

Author(s):

Rui SUN

Keyword(s):

Numerical Simulation ◽

Coal Combustion ◽

Combustion Process ◽

Pulverized Coal ◽

Pulverized Coal Combustion ◽

Firing Furnace

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Effects of Alkali and Alkaline Earth Metals on NOx Reduction in Coke Combustion

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.634-638.522 ◽

2013 ◽

Vol 634-638 ◽

pp. 522-525 ◽

Cited By ~ 1

Author(s):

Yan Guang Chen ◽

Hong Jing Han ◽

Jia Lu ◽

Dan Dan Li ◽

Jin Lian Li ◽

...

Keyword(s):

Alkaline Earth ◽

Nox Reduction ◽

Combustion Process ◽

Fixed Bed ◽

Alkaline Earth Metals ◽

Reduction Ratio ◽

Nox Emission ◽

Fixed Bed Reactor ◽

Impregnation Method ◽

Loading Amount

A series of coke samples with loading alkali and alkaline earth metals were prepared by the impregnation method, the NOx emission were investigated in a silica fixed bed reactor in the combustion process of raw coke and coke modified by Na, K, Ca and Mg. The results show that Na, K, Ca and Mg play in-situ catalytic effects on the NOx reduction reactions. When the loading amount of Na2CO3 is 2.0%, the NOx reduction ratio was around 17.4%, when the loading of K2CO3 is 2.0%, the amount of NOx emission is reduced by 26.5%. When the loading of CaCl2 is 2.0%, the amount of NOx emission is reduced by 22.3%. When the loading of MgCl2 is 2.0%, the NOx reduction ratio is about 10.9%.

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