scholarly journals THE INFLUENCE OF OPERATIONAL AND STRUCTURAL PARAMETERS ON THE UNEVENNESS OF THE TEMPERATURE FIELD AT THE OUTLET OF THE GAS TURBINE COMBUSTION CHAMBER

2020 ◽  
pp. 80-87
Author(s):  
Ali Sulaiman ◽  
◽  
Bilal Mingazov ◽  
Yury Aleksandrov ◽  
The Nguyen ◽  
...  
Keyword(s):  
Temperature Field ◽  
Combustion Chamber ◽  
Gas Flow ◽  
Structural Parameters ◽  
Temperature Fields ◽  
Mixing Process ◽  
Operational Parameters ◽  
Air Jets ◽  
Annular Jet ◽  
Secondary Air

Ensuring acceptable temperature field non-uniformity at the outlet of the combustion chamber is a very important requirement that determines the reliability and durability of the turbine. The formation of non-uniformity is determined by the nature of the interaction of the secondary air jets with the gas flow in the flame tube and depends on many factors, both structural and operational parameters. In this paper, we propose to evaluate the non-uniformity of the temperature fields at the outlet of the combustion chamber using a mixing coefficient that determines the quality of mixing jets of secondary air with a gas stream in the mixer. Based on the equation of turbulent diffusion during the flow of an annular jet into a limited space, an analytical dependence is obtained in the work that allows one to calculate the mixing process in the combustion chamber. The connection of the mixing process with the formation of temperature fields is established. Based on this, dependences are obtained for calculating the nonuniformity of temperature fields. Their satisfactory agreement with experimental data was shown. The found dependences allow one to analyze the influence of various parameters on the non-uniformity of temperature fields and accelerate the refinement of the combustion chamber by this parameter. The possibility of predicting the effect of various parameters on the unevenness of temperature fields is shown. The presence of the optimal value of the degree of opening of the mixer is confirmed, at which the minimum value of the unevenness of the temperature field at the outlet of the combustion chamber is achieved. Therefore, the analytical relationships found in the work allow optimizing the design of the mixer in the combustion chamber and the distribution of secondary air in it in order to reduce the unevenness of the temperature fields at the outlet of the combustion chamber.

Numerical Analysis of Flow Fields and Temperature Fields in a Regenerative Heating Furnace for Steel Pipes

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Yi Han ◽  
Feng Liu ◽  
Xin Ran
Keyword(s):  
Temperature Field ◽  
Flow Field ◽  
Flow Velocity ◽  
Gas Flow ◽  
Flow Fields ◽  
Heating Furnace ◽  
Temperature Fields ◽  
Turbulent Layer ◽  
Steel Pipes ◽  
Pipe Blanks

In the production process of large-diameter seamless steel pipes, the blank heating quality before roll piercing has an important effect on whether subsequently conforming piping is produced. Obtaining accurate pipe blank heating temperature fields is the basis for establishing and optimizing a seamless pipe heating schedule. In this paper, the thermal process in a regenerative heating furnace was studied using fluent software, and the distribution laws of the flow field in the furnace and of the temperature field around the pipe blanks were obtained and verified experimentally. The heating furnace for pipe blanks was analyzed from multiple perspectives, including overall flow field, flow fields at different cross sections, and overall temperature field. It was found that the changeover process of the regenerative heating furnace caused the temperature in the upper part of the furnace to fluctuate. Under the pipe blanks, the gas flow was relatively thin, and the flow velocity was relatively low, facilitating the formation of a viscous turbulent layer and thereby inhibiting heat exchange around the pipe blanks. The mutual interference between the gas flow from burners and the return gas from the furnace tail flue led to different flow velocity directions at different positions, and such interference was relatively evident in the middle part of the furnace. A temperature “layering” phenomenon occurred between the upper and lower parts of the pipe blanks. The study in this paper has some significant usefulness for in-depth exploration of the characteristics of regenerative heating furnaces for steel pipes.

Capturing Nongradient Transport in Nonequilibrium Gas Flow

2008 ◽  
Author(s):  
X. J. Gu ◽  
D. R. Emerson
Keyword(s):  
Temperature Field ◽  
Couette Flow ◽  
Transport Mechanism ◽  
Gas Flow ◽  
Transport Model ◽  
Temperature Fields ◽  
Order Moment ◽  
Nonequilibrium Gas ◽  
The One ◽  
Planar Couette Flow

A higher order moment method is employed to construct the transport model for nonequilibrium gas flow in microscale geometries. The one dimensional planar Couette flow was chosen to demonstrate the significance of capturing the nongradient transport phenomena in the prediction of velocity and temperature fields. For planar Couette flow in the transition regime, the velocity profile is nonlinear and the induced temperature field is no longer parabolic. These features are attributed to the nongradient transport mechanism in a nonequilibrium gas. Furthermore, it is revealed that, for a given temperature field, the gradient transport model overestimates the heat transfer significantly. This, again, can be compensated by the nongradient transport mechanism.

Optimization of Secondary Air Distribution in Biomass Boiler by CFD Analysis

2016 ◽  
Vol 832 ◽  
pp. 231-237 ◽  
Author(s):  
Martin Lisý ◽  
Jiří Pospíšil ◽  
Otakar Štelcl ◽  
Michal Špilaček
Keyword(s):  
Combustion Chamber ◽  
Flue Gas ◽  
Gas Flow ◽  
Air Distribution ◽  
Cfd Modelling ◽  
Biomass Boiler ◽  
Air Supply ◽  
Secondary Air ◽  
Emission Limits ◽  
The Impact

This paper deals with a use of CFD modelling for optimization of supply of secondary combustion air in the two-chamber biomass boiler combusting very wet biomass (capacity ca. 200 kW). Objective of the analyse is to observe the impact of diameter of a secondary air supply pipe and air flow velocity on mixing of the secondary air with flue gas in the combustion chamber. The numerical model of the experimental boiler was build up for subsequent utilizing of CFD computation based on finite element method. The commercial code STAR-CD was used for carried out parametrical studies. Series of calculations were carried out for four different diameters of air distribution pipes and for 3 different air velocities in distribution orifice. Quality of air dispersion in flue gas flow was assessed in the vertical cross section lead in the end of the combustion chamber. The results of calculation were verified on the experimental installation of the boiler. Influence of secondary air mixing on emission production was measured and analysed. Emissions of pollutants for recommended air distribution comply with emission limits stipulated in the most stringent class 5 according to ČSN-EN 303-5 as well as with emission limits under Regulation No. 405/2012 Sb.

Numerical Simulation of Combustion Processes and Analysis of Temperature Field Non-Uniformity in GTE-65 Gas Turbine Combustor

2010 ◽  
Author(s):  
Dmitry Tarasov ◽  
Alexander Lebedev ◽  
Nikolay Simin ◽  
Viktor Grinevich
Keyword(s):  
Experimental Data ◽  
Temperature Field ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Control Algorithm ◽  
Field Conditions ◽  
Pollutant Emissions ◽  
Temperature Fields ◽  
Operation Conditions ◽  
Partial Load

Our company has tested annular combustion chamber, being one of main components of hot gas path for GTE-65 gas turbine in mid power class. In order to arrange gaseous fuel oxidation process a method of lean homogenized air-fuel mixture burning is realized in the combustor. The same type two-contour burner modules are installed on the combustor cap in two rows by 60 burners in a row (120 burners in all). To optimize control algorithm and confirm main performances a model compartment, representing 1/12 part (segment) of actual combustion chamber, was produced. The tests have been conducted with using GP “Ivchenko-Progress” and OJSC “Power Machines” test rigs on modes from ignition to full load. Stable firing mode and pollutant emissions have been determined and the liner temperature condition and temperature field unevenness have been checked. The combustor control algorithm was optimized. As a result of the conducted tests there were confirmed environmental requirements to the combustor NOx emissions (less than 25 ppm). Mathematical simulating machine was being used to predict the combustor operation performances at the gas turbine operating in field conditions. 3D numerical analysis was carried out to predict the temperature and NOx fields before the experiment preparation. In order to meet the numerical model with the test conditions after the experiment the boundary conditions were specified (fuel / air temperature and mass flow rate). Full and partial load calculations were performed for simulation and field operation conditions. The calculation results were compared with experimental data obtained in the course of bench test. Errors obtained by comparison with numerical and experimental data were as follows: • full model pressure drop: ∼ 3–4%; • ratio of peripheral and radial non-uniformities of temperature fields: ∼ 2%; • nitrogen oxides at various operation modes: maximum 25 ppm. The obtained results make it possible to go on the combustor testing in field conditions.

Pressure Driven Temperature Field in a Combustion Chamber

2004 ◽  
Author(s):  
Fernando Z. Sierra ◽  
Janusz Kubiak ◽  
Gustavo Urquiza
Keyword(s):  
Temperature Field ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Numerical Computation ◽  
High Temperatures ◽  
Characteristic Temperature ◽  
Air Flow ◽  
Combined Cycle ◽  
Auxiliary Equipment ◽  
Secondary Air

In this work numerical computation has been applied to investigate the temperature field in a gas turbine combustion chamber. The simulation considered pressure imbalance conditions of air flow between primary and secondary inlets. The combustion chamber under study is part of a 70 MW gas turbine from an operating combined cycle power plant. The combustion was simulated with proper fuel-air flow rate assuming stoichiometric conditions. Characteristic temperature and pressure fields were obtained under constant boundary conditions of air inlet. However, with pressure distribution imbalances of the order of 3 kPa between primary and secondary air inlets, excessive heating in regions other than the combustion chamber core were obtained. Over heating in these regions helped to explain what was observed to produce permanent damage to auxiliary equipment surrounding the combustion chamber core, like the cross flame pipes. It is observed that high temperatures which normally develop in the central region of the combustion chamber may reach other surrounding upstream regions by modifying slightly the air pressure. Scanning microscope examination of the damaged material confirmed that it was exposed to high temperatures such as predicted through the numerical computation.

A 3D Model of Combustion in Large-Scale Circulating Fluidized Bed Boilers

2004 ◽  
Vol 2 (1) ◽  
Author(s):  
Karsten Luecke ◽  
Ernst-Ulrich Hartge ◽  
Joachim Werther
Keyword(s):  
Combustion Chamber ◽  
Fluidized Bed ◽  
Large Scale ◽  
Gas Flow ◽  
Circulating Fluidized Bed ◽  
Combustion Process ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Cross Sectional ◽  
Secondary Air

In a circulating fluidized bed (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. 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 is quantified by defining dispersion coefficients, and finally the combustion process itself, i.e. the reaction kinetics, is modelled. The model was validated against data from measurements in the large-scale combustor of Chalmers University of Technology in Göteborg/Sweden. Insufficient fuel mixing generated mal-distributions of locally released volatiles, which were the basis for the uneven reactants distribution at steady-state. In the case of two-stage operation, the injected secondary air did not reach immediately the reactor's center but was slowly mixed with the main gas flow. The concentration gradients hardly vanish before the exit of the combustion chamber.

Modeling and Experiment on Combustion Characteristics for Biomass Rotary Burner

2020 ◽  
Vol 04 ◽  
Author(s):  
Guohai Jia ◽  
Lijun Li ◽  
Li Dai ◽  
Zicheng Gao ◽  
Jiping Li
Keyword(s):  
Combustion Chamber ◽  
Combustion Temperature ◽  
Combustion Efficiency ◽  
Middle Part ◽  
Combustion Characteristics ◽  
Maximum Temperature ◽  
Excess Air ◽  
Element Simulation ◽  
Excess Air Coefficient ◽  
Secondary Air

Background: A biomass pellet rotary burner was chosen as the research object in order to study the influence of excess air coefficient on the combustion efficiency. The finite element simulation model of biomass rotary burner was established. Methods: The computational fluid dynamics software was applied to simulate the combustion characteristics of biomass rotary burner in steady condition and the effects of excess air ratio on pressure field, velocity field and temperature field was analyzed. Results: The results show that the flow velocity inside the burner gradually increases with the increase of inlet velocity and the maximum combustion temperature is also appeared in the middle part of the combustion chamber. Conclusion: When the excess air coefficient is 1.0 with the secondary air outlet velocity of 4.16 m/s, the maximum temperature of the rotary combustion chamber is 2730K with the secondary air outlet velocity of 6.66 m/s. When the excess air ratio is 1.6, the maximum temperature of the rotary combustion chamber is 2410K. When the air ratio is 2.4, the maximum temperature of the rotary combustion chamber is 2340K with the secondary air outlet velocity of 9.99 m/s. The best excess air coefficient is 1.0. The experimental value of combustion temperature of biomass rotary burner is in good agreement with the simulation results.

Mixing Enhancement of Two Gases in a Microchannel Using DSMC

2013 ◽  
Vol 307 ◽  
pp. 166-169 ◽  
Author(s):  
Masoud Darbandi ◽  
Elyas Lakzian
Keyword(s):  
Gas Flow ◽  
Flow Analysis ◽  
Direct Simulation Monte Carlo ◽  
Equilibrium Composition ◽  
Mass Composition ◽  
Mixing Enhancement ◽  
Mixing Process ◽  
Result Section ◽  
Flow Through ◽  
Simulation Monte Carlo

Microgas flow analysis may not be performed accurately using the classical CFD methods because of encountering high Knudsen number regimes. Alternatively, the gas flow through micro-geometries can be investigated reliably using the direct simulation Monte Carlo (DSMC) method. Our concern in this paper is to use DSMC to study the mixing of two gases in a microchannel. The mixing process is assumed to be complete when the mass composition of each species deviates by no more than ±1% from its equilibrium composition. To enhance the mixing process, we focus on the effects of inlet-outlet pressure difference and the pressure ratios of the incoming CO and N2 streams on the mixing enhancement. The outcome of this study is suitably discussed in the result section.

Multiflame Patterns in Swirl-Driven Partially Premixed Natural Gas Combustion

2002 ◽  
Vol 125 (1) ◽  
pp. 40-45 ◽  
Author(s):  
K. P. Vanoverberghe ◽  
E. V. Van den Bulck ◽  
M. J. Tummers ◽  
W. A. Hu¨bner
Keyword(s):  
Natural Gas ◽  
Combustion Chamber ◽  
Gas Flow ◽  
State Transition ◽  
Gas Combustion ◽  
Bifurcation Phenomena ◽  
Major Species ◽  
Partially Premixed ◽  
Natural Gas Combustion ◽  
Low Nox Emission

Five different flame states are identified in a compact combustion chamber that is fired by a 30 kW swirl-stabilized partially premixed natural gas burner working at atmospheric pressure. These flame states include a nozzle-attached tulip shaped flame, a nonattached torroidal-ring shaped flame (SSF) suitable for very low NOx emission in a gas turbine combustor and a Coanda flame (CSF) that clings to the bottom wall of the combustion chamber. Flame state transition is generated by changing the swirl number and by premixing the combustion air with 70% of the natural gas flow. The flame state transition pathways reveal strong hysteresis and bifurcation phenomena. The paper also presents major species concentrations, temperature and velocity profiles of the lifted flame state and the Coanda flame and discusses the mechanisms of flame transition and stabilization.

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