A Numerical Analysis of Pulverized Coal Combustion in a Multiburner Furnace (original) (raw)

Two approaches for numerical simulation of processes in systems for pulverised coal combustion

2005

The paper presents the overall frame, principal steps and some results of numerical modelling of power boiler furnace on pulverised coal, with tangential disposition of the burners. Complex 3D furnace geometry, two-phase turbulent flow, coal combustion, as well as heat transfer, have been emphasized. Two approaches of numerical modelling were employed in the investigation, both based on Euler-Lagrangean two-phase flow concept and gas phase semiempirical k-ε turbulence model. The first approach is based on specially developed comprehensive model of processes in pulverised coal furnace. In the second case, commercial CFD code is utilised for creation of 3-D furnace model. Some distinctive results concerning the examined boiler performance are presented graphically. On a basis of comparison between the simulation predictions and available site measurements, a conclusion can be drawn that the models produce realistic insight into the furnace processes. Qualitative agreement indicates reasonability of the calculations and validates the employed sub-models.

A complete review based on various aspects of pulverized coal combustion

International Journal of Energy Research, 2019

Coal is the most abundant energy source, and around 40% of the world's electricity is produced by coal combustion. The emission generated through it put a constraint on power production by coal combustion. There is a need to reduce the emissions generated through it to utilize the enormous energy of coal for power production. Detailed understanding of various aspects of coal combustion is required to reduce the emissions from coal-fired furnaces. The aim of present paper is to review various aspects of pulverized coal combustion such as oxy-fuel combustion, co-combustion of coal and biomass, emissions from pulverized coal furnaces, ash formation and deposition, and carbon capture and sequestration (CCS) technologies to outline the progress made in these aspects. Both experimental and numerical aspects are included in this review. This review also discusses the thermodynamic aspects of the combustion process. Furthermore, the effect of various submodels such as devolatilization models, char combustion models, radiation models, and turbulent models on the process of pulverized coal combustion has been investigated in this paper.

Numerical modelling of pulverised coal combustion

2017

Many thermal power generation plants rely on combustion of pulverised coal carried out in large furnaces. Design and improvement of these furnaces can be effectively assisted by using numerical modelling with Computational Fluid Dynamics (CFD) techniques to develop a detailed picture of the conditions within the furnace, and the effect of operating conditions, coal type, and furnace design on those conditions. The equations governing CFD models of pulverised coal combustion are described, with a focus on sub-models needed for devolatilisation, combustion and heat transfer. The use of the models is discussed with reference to examples of CFD modelling of brown coal fired furnaces in the Latrobe Valley in Australia and black coal fired furnaces described in the literature. Extensions to the CFD models that are required to tackle specific industrial and environmental issues are also described. These issues include control of NOx and SOx emissions and the effect of slagging and fouling on furnace and boiler operation.

An Experimental Study of MILD Combustion of Pulverized Coal in a Recuperative Furnace

Moderate or Intense Low Oxygen Dilution (MILD) combustion technology has been identified as an innovative approach to reducing combustion generated pollutants and increasing thermal efficiency. The present experimental study investigates the performance and operation characteristics of a parallel jet MILD combustion furnace using pulverized coal as the fuel. Kingston brown coal and Bowen basin anthracite coal with particle size in the range of 38-180 µm was injected into the furnace using CO 2 as a carrier gas. It was found that MILD conditions are achievable for coal particles without additional pre-heating of the air. Measurements of in-furnace combustion gas concentration of CO and NO, exhaust gas emissions, and furnace temperatures are presented. The in-furnace combustion data are analyzed to better understand the combustion characteristics of coal under the MILD condition in a recuperative furnace. High CO concentration was recorded at lower portion of the furnace for brown coa...

Model Study of the Effects of Coal Properties and Blast Conditions on Pulverized Coal Combustion

ISIJ International, 2009

High coal burnout within the raceway is important for the operation of a blast furnace. It is usually achieved by adjusting some operational parameters in practice. In this work, a three-dimensional model we developed recently is used to investigate the effects of some key operational parameters on coal burnout. The results confirm that notable improvements in final burnout can be achieved for coals with more fine particles and high volatile matter, and by higher oxygen enrichment. The use of high blast temperature can increase coal burnout, but the further increase in blast temperature over 1 200°C has little effect on final burnout. The effects of these parameters on other combustion characteristics are also analysed, in terms of volatile content, temperature field and gas species distribution, aiming to understand the underlying mechanisms behind these improvements. It is demonstrated that local oxygen supply is very important for high burnout in addition to coal properties. In addition, it is necessary to consider the raceway region when investigating the effects of these variables on coal burnout. This study helps identify appropriate and cheaper coals and optimise operating conditions to maximize the benefits of pulverized coal injection.

MILD Combustion of Pulverised Coal in a Recuperative Furnace

Moderate or Intense Low Oxygen Dilution (MILD) combustion of pulverised coal in a laboratory scale recuperative furnace is investigated in this study. High volatile Kingston brown coal and low volatile Bowen basin black coal with particle size in the range of 38-180 m were injected into the furnace using either CO 2 or N 2 as a carrier gas. A water cooled sampling probe was used to conduct in-furnace gas sampling. Measurements of in-furnace gas concentration of CO and NO, exhaust gas emissions, and in-furnace temperatures are presented. A CFD model was developed for the CO 2 carried Kingston brown coal case and results are compared with experimental data. Ash content analysis showed that black coal was not burnt effectively, which is thought to be due to the relatively short furnace residence times.

Study on Combustion Performances of Burners in Furnace in Coal Fired Power Plants

Steam generation are one of the critical components of a thermal powerplant. Studies of the performance of combustion in a steam generator are very complex in nature. In this work numerical simulations are used to investigate the characteristics of gas and coal particle two-phase flow in boiler furnaces. In order to examine the detailed behavior of the flow different load conditions were given with varying the velocity of flow of air and fuel. Flow characteristics with multiple number of burners and firing at different locations resembeling variation of load is studied. Studies of effect of different operating conditions are studied using commercial code FLUENT. To determine velocity, temperature characteristics a 3D combustor model isused in this case study. Change of size in burners is done in order to find the temperature profiles changes in furnace. Analyses of particle trajectories are done so as to study the emission characteristics, fouling on burners etc.

Factors Influencing the Reburning Process in a Tangentially-Fired Pulverized Coal Furnace

Inżynieria Mineralna, 2016

A numerical simulation of bituminous coal reburning in a full-scale tangentially-fired boiler has been conducted with CFD method in order to study the effects of reburn zone length, the height of reburn nozzles, the stoichiometric ratio in reburn zone, the reburn fuel fraction and the reburn coal fineness on NO x reduction efficiency and unburned carbon in fly ash. The results indicate the largest value of NO x reduction efficiency relative to the height of reburn nozzles zone; the increase of NO x reduction efficiency with reburn zone length, reburn fuel fraction and the decrease of reburn coal particle size; the increase of burnout performance of coal relative to the coal particle size.

Pulverized coal torch combustion in a furnace

Journal of Physics: Conference Series, 2019

Aerodynamics of flame combustion of a pulverized coal was studied experimentally using a laboratory setup with a thermal power of 25 kW. The axial and tangential velocity profiles were measured with the co-and counter-swirl of the first and second degrees of the burner. Averaged velocity profiles were measured by a two-component LDA system. The temperature was also measured on the walls and axis of sections of the pulverized coal burner. The temperature distributions were obtained at different coal dust flow rates as well as at co-and counter-swirl. The results obtained allow us to conclude about the efficiency of flow mixing at pulverized coal combustion.

CFD Modeling of Pulverized Coal Combustion in an Industrial Burner

Volume 1: Aircraft Engine; Ceramics; Coal, Biomass and Alternative Fuels; Controls, Diagnostics and Instrumentation, 2012

The accurate prediction of pulverized coal combustion in industrial application still remains a great challenge. This is mainly due to the lack of high quality experimental data acquired during the operation of industrial plants.