scholarly journals Numerical Investigation on Coal Combustion in Ultralow CO2 Blast Furnace: Effect of Oxygen Temperature

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 877 ◽  
Author(s):  
Zhenfeng Zhou ◽  
Qiujie Yi ◽  
Ruihao Wang ◽  
Guang Wang ◽  
Chunyuan Ma
Keyword(s):  
Coal Combustion ◽  
Room Temperature ◽  
Combustion Process ◽  
Three Dimensional ◽  
Cooling Effect ◽  
Combustion Mechanism ◽  
Three Dimensional Model ◽  
Combustion Technology ◽  
Top Gas Recycling ◽  
Effect Of Oxygen

The cooling effect of room-temperature oxygen in oxygen blast furnaces with top gas recycling (TGR-OBF) delays the coal combustion process. To further explore the oxygen–coal combustion mechanism and intensify coal combustion in TGR-OBF, the effect of oxygen temperature on coal combustion was investigated using computational fluid dynamics (CFD). A three-dimensional model was developed to simulate the lance–blowpipe–tuyere–raceway of TGR-OBF. The effect of oxygen temperature at the same oxygen velocity and mass flow on coal combustion was investigated. Results showed the cooling effect of room-temperature oxygen was weakened, and the coal burnout was greatly increased with the increase in oxygen temperature. In particular, the coal burnout increased from 21.64% to 81.98% at the same oxygen velocity when the oxygen temperature increased from 300 to 500 K. The results provide useful reference for the development of TGR-OBF and coal combustion technology.

Modeling of Solids and Gas Mixing Effects in Large-Scale CFB Combustors

2003 ◽  
Author(s):  
Karsten Luecke ◽  
Ernst-Ulrich Hartge ◽  
Joachim Werther
Keyword(s):  
Combustion Chamber ◽  
Residence Time ◽  
Large Scale ◽  
Control Volume ◽  
Combustion Process ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Cross Sectional ◽  
Fuel Feed ◽  
Cross Section Area

In a CFB combustor the reacting solids are locally fed into the combustion chamber. These reactants have to be dispersed across the reactor’s cross-sectional area. Since the rate of mixing is limited this leads to a mal-distribution of the reactants and to locally varying reaction conditions. In order to describe the influence of mixing a three-dimensional model of the combustion chamber is suggested here. The model is divided into three sub-topics. First, the flow structure in terms of local gas and solids velocities and solids volume concentrations is described. Second, mixing of the solids and the gas phase has to be quantified by defining dispersion coefficients, and finally the combustion process itself, i.e. the reaction kinetics, has to be modeled. Employing the information of the three sub-models mass balances for the reactants at each finite control volume inside the CFB combustion chamber can be formulated. The model was validated against data from measurements in the large-scale combustor of Chalmers University of Technology in Go¨teborg/Sweden. Concentration gradients concerning the char phase are only moderate. However, the spatial distribution of the oxygen shows strong non-uniformities, especially under conditions of staged combustion. In further predictive calculations, the influence of the fuel supply arrangement on the emissions of industrial sized CFB boilers was studied. Furthermore, the influence of the fuel composition on the feeding technique has been examined. High volatile fuels tend to form plumes of unburned hydrocarbons near the fuel feed point, and might therefore need more feed points per square meter cross-section area. Since the average gas residence time in the primary cyclone of a CFB plant is about 30–40% of the total gas residence time, a considerable burn-off of not completely oxidized gas species may occur here. An effectively used cyclone may remedy to a certain extent the negative impacts of incomplete mixing in the combustion chamber.

scholarly journals Coal combustion modelling in a frontal pulverized coal-fired boiler

2018 ◽  
Vol 46 ◽  
pp. 00010
Author(s):  
Paweł Madejski
Keyword(s):  
Coal Combustion ◽  
Gas Flow ◽  
Combustion Process ◽  
Three Dimensional ◽  
Pulverized Coal ◽  
Operational Conditions ◽  
Power Plant Boiler ◽  
Combustion Modelling ◽  
Flow Through ◽  
Plant Boiler

The paper presents results of numerical modelling of pulverized coal combustion process in the coal-fired boiler. In the numerical model, coal combustion process includes particle heating, devolatilization, char combustion, as well as turbulent flow and radiative heat transfer was modelled. Presented modelling results were carried out using the Open Source CFD code - Code_Saturne created and developed by EDF R&D and were used to study the combustion of coal in power plant boiler with the objective of simulating the operational conditions and identifying factors of inefficiency. The behaviour of the flow of air and pulverized coal through the burners was modelled, and the three-dimensional flue gas flow through the combustion chamber and heat exchangers was reproduced in the simulation.

CFD Assisted Design of Micro GT Combustor

2009 ◽  
Author(s):  
Yeshayahou Levy ◽  
Vladimir Erenburg ◽  
Yakov Goldman ◽  
Valery Sherbaum ◽  
Vitaly Ovcharenko
Keyword(s):  
Heat Transfer ◽  
Cfd Simulation ◽  
Combustion Process ◽  
Three Dimensional ◽  
Heat Radiation ◽  
Working Fluid ◽  
Stoichiometric Ratio ◽  
Three Dimensional Model ◽  
Successful Operation ◽  
Predicted Values

The work presents the development of a micro-combustor design, where the combustion process was simulated by CFD and tested experimentally. The inner diameter of the first model was 5.5 mm, the exit diameter 2.5 mm, and the length 24.5 mm. The designed heat release was 200W. Some modifications of the microcombustor were studied. Three-dimensional model for combustion simulations was used. The ‘conjugate heat transfer’ methodology, based on a simultaneous solution of the heat transfer equations for gas and combustor walls, coupled with equations for the working fluid, enabled the prediction of the combustor wall temperatures. To check model convergence 2 simulations with different number of cells were carried out. Effect of heat radiation was also studied by the CFD simulation. The fuel is methane and stoichiometric ratio was simulated. Reactive flow calculations were carried out with a two-step reaction. The analysis of the simulated results was based on the obtained velocity profiles, concentration and temperature distributions within the liner. Preliminary simulations showed that the first combustor design had inefficient combustion. The reason was poor mixing of methane and air inside the mixing chamber and deterioration of the combustion by dilution holes. Consequently, the combustor design was modified and simulated. The simulation showed that the modification significantly improved mixing and combustion process and better combustion was provided. Due to complexity associated with performing combustion experiments in such small dimensions, only limited data could be recorded. A small combustor was manufactured and tests and demonstrated its successful operation. Measurements of temperature and optical UV-VIS-IR - emissions at the combustor exit were obtained. The experimental and simulation results are compared and a good qualitative agreement was found between the experiments and the predicted values.

Pressurised Oxy-Coal Combustion Rankine-Cycle for Future Zero Emission Power Plants: Technological Issues

2009 ◽  
Author(s):  
Marco Gazzino ◽  
Giovanni Riccio ◽  
Nicola Rossi ◽  
Giancarlo Benelli
Keyword(s):  
Coal Combustion ◽  
Carbon Capture ◽  
Power Plants ◽  
Process Integration ◽  
Scale Up ◽  
Combustion Process ◽  
Rankine Cycle ◽  
Intermediate Step ◽  
Combustion Technology ◽  
Zero Emission

Among possible options to capture carbon dioxide, pressurised oxy-fuel combustion is a promising one. Accordingly, Enel teamed with Itea and Enea to develop a pressurised oxy-combustion technology. Currently, extensive tests have been carried out at 4 bar on a 5 MWt facility based in Gioia del Colle (Southern Italy). By starting from the know-how gained on that scale, Enel planned to build by 2010 an experimental 48 MWt demo-plant, based on the same pressurised combustion process introduced above. This will be the necessary intermediate step for the further scale-up towards a zero emission plant of industrial scale. This paper is the prosecution of a previous publication presenting the process design and energy analysis of a power cycle integrating the developed pressurised oxy-coal combustion technology with a Rankine cycle including carbon capture. After having briefly presented the pressurised oxycombustion project carried out at Enel, the paper focuses on technology issues related to the proposed cycle and the related process integration, with respect to main components.

Numerical Simulation on Effect of Nozzle-Hole Layout on Spray Characteristics and Combustion in a DI Diesel Engine

2012 ◽  
Vol 476-478 ◽  
pp. 448-452
Author(s):  
Jun Zhang ◽  
Chang Pu Zhao ◽  
Nai Zhuan Chen ◽  
Da Lu Dong ◽  
Bo Zhong
Keyword(s):  
Numerical Simulation ◽  
Diesel Engine ◽  
Direct Injection ◽  
Combustion Process ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Spray Characteristics ◽  
Fuel Atomization ◽  
Di Diesel Engine ◽  
Nozzle Hole

Diesel spray characteristics are closely related to the combustion of the engine where the spray tip penetration and the fuel atomization play a key role especially for direct injection (DI) diesel engine. With different nozzles, the fuel atomization and evaporation will be different thereby affecting the combustion and emission characteristics. A three-dimensional model is built based on the parameters of a DI diesel engine, and its validation is also validated. Three nozzle-hole layouts are designed in this research, including the conventional hole, multi-hole, and group-hole. The spray characteristics and combustion process are studied with three different nozzle-hole layouts by the way of numerical simulation. Further more, the effect of inter-hole spacing of group-hole nozzle on the evaporation rate and combustion process is researched here.

Investigation on the Evolution of the Coal Macromolecule in the Process of Combustion With the Molecular Dynamics Method

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Bonan Xu ◽  
Hanhui Jin ◽  
Hanqing Li ◽  
Yu Guo ◽  
Jianren Fan
Keyword(s):  
Molecular Dynamics ◽  
Chemical Reactions ◽  
Coal Combustion ◽  
Ring Opening ◽  
Combustion Process ◽  
Three Dimensional ◽  
Structural Evolution ◽  
Coal Particles ◽  
Dynamics Method ◽  
Detailed Chemical

Abstract It is reported that a three-dimensional cross-linked macromolecular structure with heterogeneous inorganic and organic compositions widely exists in coal particles. The macromolecules usually represent the rank transition of more than 75% of the carbon (C) content of coal particles. In order to know the coal combustion process better, it is important to specifically study the evolution of the coal macromolecule during combustion. In this paper, the structural evolution and the detailed oxidization reactions of a coal macromolecule during the process of combustion are numerically studied with the reactive force field (ReaxFF) molecular dynamics (MD) method, in which the carbon (C) and hydrogen (H) atoms are fully oxidized to CO2 and H2O, respectively. It is found that the coal macromolecule experiences three main stages sequentially: the cleavage, the ring opening, and the oxidation. The heteroatoms (O, N, and S) inside the coal macromolecule are found to play important roles throughout the whole combustion process. The detailed chemical reactions with their occurrence frequencies show that the chemical reactions with O2 mainly occur in C1–4 fragments, and the C1–2–H–O fragments widely exist in the system before they are finally oxidized to CO or CO2.

Analysis of the Flow in the Combustor—Transition Piece Considering the Variation in the Fuel Composition

2011 ◽  
Vol 3 (2) ◽  
Author(s):  
J. Arturo Alfaro-Ayala ◽  
A. Gallegos-Muñoz ◽  
J. Manuel Riesco-Ávila ◽  
M. Flores-López ◽  
A. Campos-Amezcua ◽  
...  
Keyword(s):  
Radial Direction ◽  
Combustion Process ◽  
Three Dimensional ◽  
Velocity Profiles ◽  
Maximum Temperature ◽  
Fuel Composition ◽  
Temperature Profiles ◽  
Three Dimensional Model ◽  
Order Polynomial ◽  
Transition Piece

An analysis of the flow that depends on the fuel composition (natural gas) in the combustor–transition piece system, applying computational fluid dynamics, is presented. The study defines the velocity and temperature profiles at the exit of the transition piece and the hot streak along the system. The variation of the composition in the fuel depends of the amount of N2 contained in the fuel, and the hot track influences on the temperature distribution at the input of the first stage of vanes and blades of the gas turbine. The study takes place in a three-dimensional model in steady state using FLUENT® 6.3.26, applying the k-ε turbulence model and chemical equilibrium to the combustion process. The results show the influence of the transition piece geometry over the velocity and temperature profiles, principally, in the radial direction. The velocity profiles on the radial direction can be represented by six order polynomial and the temperature profile by third order polynomial. The temperature and velocity profiles keep a symmetry profile and they can be represented by six order polynomial at the circumferential direction. Knowing these profiles, it is possible to compute a more exact study of the heat transfer at vanes and blades of the first stage of the turbine to evaluate the performance and life of them. On the other hand, considering from 2% to 10% of N2 in the fuel composition, the maximum temperature is reduced in the combustion process and consequently the NOx emissions too.

Sign in / Sign up

Export Citation Format

Share Document