DIFFERENT FUELS ASSESSMENT IN GAS
TURBINE COMBUSTION CHAMBER FOR
PRE-MIXED AND DIFFUSE FLAME
Federal University of Itajubá
Authors: Profa. Dra Lucilene de Oliveira Rodrigues
Prof. Dr.Marco Antônio Rosa do Nascimento
Federal University of Itajubá
Founded – 1913 by TEODOMIRO SANTIAGO
Federal University of Itajubá
I – Thermal Electricity & Cogeneration
II – Technologies for Distributed Generation
III – Energetic Used Of Biomass
IV – Refrigeration & Air-conditioning
V – Gas And Steam Turbines
VI – Modeling & Diagnostic Of Thermal Process
VII – Environment Aspects Of Use Of Biomass
Problem Description
- Annular combustion chamber design for 600kW gas
turbine engine based on reference combustion
chamber.
- Thermal aerodynamics analysis in CFD: temperature
distribution and emissions for premixed and diffuse
flames, using natural gas and biogas as fuels.
Metodology
- Initial analysis of reference combustion chamber.
- Improvements of reference geometry (if necessary).
- Design of injectors for premixed and diffuse flames.
- Numerical simulation in CFD.
- Results assessment.
Reference Annular Combustion Chamber
Combustion chamber sector (1/6) – Solar Turbines
Combustion chamber-
Solar Turbines
600 kW Gas Turbine Engine Details
Reference
Sector analysed (1/20) – Premixed flame Compressor -
turbine
Premixed flame
Diffuse Flame
Injectors Design
Definition of Parts
Periodic
Periodic
Inlet air
Ehxaustion
Periodic
Periodic
Inlet fuel
Turbulence Validation
Combustion chamber - Floxcom
Inlet air
Inlet fuel
Exhaust
Inlet air
Inlet fuel
Exhaust
Turbulence Validation
Modelo de turbulência k-ε
Modelo de turbulênciaRNG k-ε
Modelo de turbulência SST
K-e RNG
K-e
SST
Turbulence Validation
-1
-0.8
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
0.8
1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
x/L [1]
Des
vio
da
mag
nitude
de
vel
oci
dad
e A
dim
ensi
onal
[1]
RNG
K Epsilon
SST
Velocity deviation
Combustion Validation
Combustion chamber
inlet
outlet
Combustion Validation
Combustion chamber
Combustion Validation
Velocity distribution
Combustion Validation
Temperature profiles
Combustion Validation
Temperature profiles
Experimental results T = 680 ºC CFX results T = 681 ºC CFX results Tm = 558 ºC
Settings Boundary conditions:
Numerical settings
Grid: 1.105.983 and 661.989 elements (premixed and diffuse, respectively)
Turbulence Model: SST- Shear Stress Tensor
Combustion Model: BVM - Burning Velocity Model (premixed flame)
Flamelet Model (diffuse flame)
Radiation Model : Discrete Transfer
Parameter Unity Natural gas Biogas
Inlet temperature ºC 461 461
Mass flow rate air kg/s 0,4288 0,4288
Mass flow rate fuel kg/s 0,06 0,16
Mass variation fuel kg/s 0,1 0,1
Combustion Chamber Results – NG
Premixed Flame
Recirculation details
Velocity distribution
Combustion Chamber Results – NG
Premixed Flame
T = 664ºC
Mc=0,06 kg/s
Temperature profiles
Combustion Chamber Results – NG
Premixed Flame
T = 852ºC
Mc=0,1 kg/s
Temperature profiles
Combustion Chamber Results – Biogas
Premixed Flame
T = 1075ºC
Mc=0,16 kg/s
Temperature profiles
Combustion Chamber Results – NG
Diffuse Flame
Velocity distribution
Combustion Chamber Results – NG
Diffuse Flame
T = 718ºC
Mc=0,06 kg/s
Temperature profiles
Combustion Chamber Results – GN
Diffuse Flame
Mc=0,1 kg/s
T = 841ºC
Temperature profiles
Combustion Chamber Results – Biogas
Diffuse Flame
Mc=0,16 kg/s
T = 1063ºC
Temperature profiles
Conclusions
- For diffuse flame, outlet temperature, CO and NO
emission are greater than premixed flame, as expected;
- The fuel shift natural gas to biogas there is a significant
change in aerodynamic and thermal behavior of the
flame, due to variation of the fuel mass flow rate and its
chemical composition;
- The analysis of flame and flow velocities are important
on the combustion chamber design.
Conclusions
- The adjustment of the geometry of the fuel injector
allowed the adjustment of the flow velocity with the flame
velocity, making the flame stable in the primary zone.
Low flame velocities associated with high flow velocities
make the flame extend towards the turbine inlet, and
consequently there are higher temperatures and NO and
CO emissions, which are not desired.
Conclusions
- The mass flow provided by the Gatecycle GE Enter
Software was based on simplified combustion models,
assessed at stoichiometric conditions, aiming at
reaching a temperature of 1123 K at the turbine inlet.
However, the CFD simulation showed that the fuel mass
flows provided by the Gatecycle GE Enter Software were
not enough for such temperature to be reached at the
turbine inlet. This way, it was necessary to change the
fuel mass flows. For the natural gas, a rise by 42% was
needed and for the biogas a reduction of 60% was
necessary, implying in alterations in the amount of
energy generated by this equipment.
- The mass flow provided by the Gatecycle GE Enter Sofware was based on simplified combustion models, assessed at stoichiometric conditions, aiming at reaching a temperature of 1123 K at the turbine inlet. However, the CFD simulation showed that the fuel mass flows provided by the Gatecycle GE Enter Software were not enough for such temperature to be reached at the turbine inlet. This way, it was necessary to change the fuel mass flows. For the natural gas, a rise by 42% was needed and for the biogas a reduction of 60% was necessary, implying in alterations in the amount of energy generated by this equipment.
Federal University of Itajubá
Thanks for your attention!!!
DIFFERENT FUELS ASSESSMENT IN GAS
TURBINE COMBUSTION CHAMBER FOR
PRE-MIXED AND DIFFUSE FLAME
Federal University of Itajubá
Authors: Profa. Dra Lucilene de Oliveira Rodrigues
Prof. Dr.Marco Antônio Rosa do Nascimento
