Numerical Study the NOx Emission Characteristics of 600MW Opposed Swirling Coal-Fired Utility Boiler

2014 ◽  
Vol 1010-1012 ◽  
pp. 847-855
Author(s):  
Ya Ming Liu ◽  
Fang Yong Li ◽  
Qi Sheng Xu
Keyword(s):  
Fly Ash ◽  
Carbon Content ◽  
Residence Time ◽  
Flue Gas ◽  
Pulverized Coal ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Cfd Model ◽  
Gas Temperature ◽  
Coal Particles

In this paper, a computational fluid dynamics (CFD) model of a 600 MW opposed swirling coal-fired utility boiler has been established to numerically study the NOx emission characteristics under different ratios of over fire air (OFA) and modes of in-service burner layers. The current CFD model had adopted a chemical percolation devolatilization (CPD) model and been validated by comparing the simulated results with the experimental data. The numerical simulation results show that, with increasing the ratio of OFA, the carbon content in fly-ash increase somewhat linearly and the NOx emission reduce significantly, and the OFA ratio of 30% is optimal with higher burnout of pulverized coal and lower NOx emission. The different in-service burner layer modes have different influences on the residence time of the pulverized-coal particles, effect of air staging in the burner region and flue gas temperature at the exit of the lower furnace. Stopping the upper burner layers can increases the residence time of the pulverized-coal particles, resulting in the reduction of the carbon content in the fly ash and the increase of the pulverized-coal burnout. The flue gas temperature at the exit of the lower furnace can also decrease, which would be helpful to reducing the slagging tendency on the surfaces of the platen superheaters.

Effects of Over Fire Air on the Combustion and NOx Emission Characteristics of a 600 MW Opposed Swirling Fired Boiler

2012 ◽  
Vol 512-515 ◽  
pp. 2135-2142 ◽  
Author(s):  
Yu Peng Wu ◽  
Zhi Yong Wen ◽  
Yue Liang Shen ◽  
Qing Yan Fang ◽  
Cheng Zhang ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Empirical Method ◽  
Nox Emission ◽  
Emission Characteristics ◽  
Cfd Model ◽  
Nitrogen Release ◽  
Computational Fluid Dynamics Cfd ◽  
Low Nox Emission

A computational fluid dynamics (CFD) model of a 600 MW opposed swirling coal-fired utility boiler has been established. The chemical percolation devolatilization (CPD) model, instead of an empirical method, has been adapted to predict the nitrogen release during the devolatilization. The current CFD model has been validated by comparing the simulated results with the experimental data obtained from the boiler for case study. The validated CFD model is then applied to study the effects of ratio of over fire air (OFA) on the combustion and nitrogen oxides (NOx) emission characteristics. It is found that, with increasing the ratio of OFA, the carbon content in fly ash increases linearly, and the NOx emission reduces largely. The OFA ratio of 30% is optimal for both high burnout of pulverized coal and low NOx emission. The present study provides helpful information for understanding and optimizing the combustion of the studied boiler

The role of pulverized coal drying temperature in fly ash carbon content and slagging of a tangentially coal-fired boiler

Fuel ◽  
2019 ◽  
Vol 257 ◽  
pp. 115951 ◽  
Author(s):  
Xin Liao ◽  
Qi Zhang ◽  
Wenhu Yang ◽  
Zhongzhu Qiu ◽  
Ruitang Guo ◽  
...  
Keyword(s):  
Fly Ash ◽  
Carbon Content ◽  
Pulverized Coal ◽  
Drying Temperature ◽  
Coal Drying

Surface Characterization of the Mechanism for Decreased Boiler Slagging via Fly Ash Surface Modification

1985 ◽  
Vol 65 ◽  
Author(s):  
Christopher J. Macey
Keyword(s):  
Fly Ash ◽  
Flue Gas ◽  
Surface Characterization ◽  
Depth Profiling ◽  
Pilot Scale ◽  
Pulverized Coal ◽  
Pulverized Coal Combustion ◽  
Utility Boilers ◽  
Combustion Experiment

ABSTRACTSlagging difficulties encountered in large, pulverized coal-fired utility boilers can be alleviated by using recently developed chemical conditioners designed to inhibit the agglomeration of molten fly ash particles. Slagging results from the impaction and accretion on the boiler interior surfaces of molten ash particles in the flue gas resulting from the combustion of coal. Electron Spectroscopy for chemical Analysis (ESCA) and ion sputtering depth profiling were utilized to examine the mechanism whereby a fuel conditioner containing copper oxychloride effectively reduced slag deposition rates during a pilot-scale, pulverized coal combustion experiment.

Experimental Study of CFB Modification Fly Ash in Concrete

2014 ◽  
Vol 1051 ◽  
pp. 743-747 ◽  
Author(s):  
Rong Jin Xu ◽  
Yan Kai Huo ◽  
Bin Teng ◽  
Si Hai Song
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Carbon Content ◽  
Fluidized Bed ◽  
Circulating Fluidized Bed ◽  
Pulverized Coal ◽  
Experimental Results ◽  
Unburned Carbon ◽  
Fluidized Bed Combustion ◽  
Effective Use

The character of the Fly ash of Circulating Fluidized Bed Boiler (CFB Fly ash) is greatly different from that of Pulverized coal furnace for its high unburned carbon. In order to make effective use of CFB Fly ash in concrete, carbon content was decreased by simulated fluidized bed combustion in laboratory and a series of concerned experiments were carried out on CFB Fly ash. The experimental results indicate that CFB modification Fly ash is possible to be used in concrete to partially replaced cement. It is a valuable reference for CFB Fly ash technical engineers.

scholarly journals Combustion adjustment and operation optimiztion of a 240 t/h circulating fluidized bed boiler

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2689-2698
Author(s):  
Xuemin Liu ◽  
Songsong Zhang ◽  
Yongqiang Chang ◽  
Zhongwei Wang ◽  
Guoli Qi
Keyword(s):  
Fly Ash ◽  
Pressure Drop ◽  
Fluidized Bed ◽  
Flue Gas ◽  
Circulating Fluidized Bed ◽  
Air Flow ◽  
Nox Emission ◽  
Unburned Carbon ◽  
Boiler Efficiency ◽  
Co Concentration

The influence of main operating parameters on boiler performance was studied, such as bed pressure drop, primary air-flow and secondary air-flow. Combustion adjustment tests were carried out on a circulating fluidized bed boiler with rated capacity of 240 t/h. From the test results, it can be seen that the loss due to exit flue gas is the largest heat loss of the boiler, accounting for more than 70% of the total heat losses. For coal fired boilers, compared with the loss due to unburned solids, the loss due to unburned gases is quite small. The unburned carbon con-tent in bottom ash is far lower than the value in fly ash. The trend of CO concentration in the exit flue gas is similar to that of the unburned carbon content in fly ash. To achieve higher boiler efficiency, the bed pressure drop is suggested to be maintained in about 8.5-9.0 kPa and the oxygen content in exit flue gas around 4%. The NOx emission concentration usually presents a negative correlation with CO concentration in exit flue gas. Through combustion adjustment and operation optimization, the NOx emission can be decreased by about 30% without affecting the boiler efficiency.

scholarly journals Numerical analysis of the flue gas-coal particles mixture flow in burner's distribution channels with regulation shutters at the TPP Nikola Tesla - A1 utility boiler

2010 ◽  
Vol 14 (2) ◽  
pp. 505-520 ◽  
Author(s):  
Nikola Zivkovic ◽  
Dejan Cvetinovic ◽  
Milic Eric ◽  
Zoran Markovic
Keyword(s):  
Flue Gas ◽  
Concentration Distribution ◽  
Distribution Channels ◽  
Pulverized Coal ◽  
Two Phase ◽  
Mixture Flow ◽  
Outlet Cross Section ◽  
Plasma Torches ◽  
Coal Particles ◽  
Nikola Tesla

Pulverized coal particles concentration distribution across the burner's distribution channels, especially where plasma torches are installed, is one of the key issues for efficient implementation of plasma system for liquid fuel free combustion support at the pulverized coal fired boilers. The possibility of pulverized coal particles concentration increase at the lower burner channels of TPP Nikola Tesla - A1 boiler using regulation shutters is analyzed experimentally and numerically. Subject of present work is two-phase flue gas-particles mixture flow in burner's distribution channels with regulation shutters installed at the TPP Nikola Tesla - A1 boiler. Aim of this work is to optimize position of implemented system of shutters to achieve desired concentration and velocity distribution in channels with plasma torches, using numerical modelling. Experimental investigation was performed for the verification of proposed mathematical model for the prediction of the analyzed two-phase flow. Based on verified model, numerical parametric analysis was done. Obtained results of gas phase velocity field, coal particles concentration field, velocity and concentration profiles clearly show the dependence between shutters position and the coal particles mass flow rate and concentration distribution at the outlet cross-section of the burner's distribution channels. According to the numerical optimization results suitable modification of the shutter system is proposed.

Effect of unburned carbon content in fly ash on the retention of 12 elements out of coal-combustion flue gas

2012 ◽  
Vol 24 (9) ◽  
pp. 1624-1629 ◽  
Author(s):  
Lucie Bartoňová ◽  
Bohumír Čech ◽  
Lucie Ruppenthalová ◽  
Vendula Majvelderova ◽  
Dagmar Juchelková ◽  
...  
Keyword(s):  
Fly Ash ◽  
Carbon Content ◽  
Flue Gas ◽  
Coal Combustion ◽  
Unburned Carbon

scholarly journals Numerical simulation of NOx emission characteristics during combustion in 350 MW supercritical cogeneration tangentially boiler

2020 ◽  
Vol 24 (5 Part A) ◽  
pp. 2717-2728
Author(s):  
Wei-Shu Wang ◽  
Zhi-Hao Huang ◽  
Miao Tian ◽  
Ji-Hong Wang ◽  
Shan-Shan Shangguan ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Nitrogen Oxides ◽  
Influencing Factors ◽  
Combustion Characteristics ◽  
Pulverized Coal ◽  
Nox Emission ◽  
Release Mechanism ◽  
Emission Characteristics ◽  
Boiler Load

In light of a 350 megawatt supercritical cogeneration tangential boiler, the combustion and the nitrogen oxides release mechanism in the furnace were numerically simulated. The combustion characteristics were analyzed, and the influencing factors, such as the pulverized coal concentration, the velocity of separated over-fire air and the boiler load, on nitrogen oxides release in the furnace were also systematically studied. The results show that the central airflow in the furnace rises spirally, and an inverted ?V? type temperature distribution is formed. The generation of nitrogen oxides can be effectively restrained by increasing the concentration of pulverized coal properly. Compared with the conventional concentration, the concentration of nitrogen oxides at the furnace exit can be reduced by 29.63% by taking high pulverized coal concentration. The concentration of NOx at the furnace exit can be drastically reduced by increasing the velocity of separated over-fire air. When decreasing boiler load, the concentration of NOx at furnace exit declines at first and then increases.

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