DIFFERENT FUELS ASSESSMENT IN GAS TURBINE COMBUSTION CHAMBER FOR PRE-MIXED AND DIFFUSE FLAME

Transcription

1 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

2 Federal University of Itajubá Founded 1913 by TEODOMIRO SANTIAGO

3 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

4 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.

5 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.

6 Reference Annular Combustion Chamber Combustion chamber sector (1/6) Solar Turbines Combustion chamber- Solar Turbines

7 600 kw Gas Turbine Engine Details Reference Compressor - turbine Sector analysed (1/20) Premixed flame

8 Injectors Design Premixed flame Diffuse Flame

9 Definition of Parts Periodic Inlet air Periodic Periodic Periodic Ehxaustion Inlet fuel

10 Turbulence Validation Inlet fuel Inlet air Exhaust Combustion chamber - Floxcom

11 Turbulence Validation Modelo de turbulência k-ε Modelo de turbulênciarng k-ε K-e RNG K-e Modelo de turbulência SST SST

12 Desvio da magnitude de velocidade Adimensional [1 Turbulence Validation RNG K Epsilon SST x/l [1] Velocity deviation

13 Combustion Validation inlet outlet Combustion chamber

14 Combustion Validation Combustion chamber

15 Combustion Validation Velocity distribution

16 Combustion Validation Temperature profiles

17 Combustion Validation Temperature profiles Experimental results T = 680 ºC CFX results T = 681 ºC CFX results Tm = 558 ºC

18 Settings Boundary conditions: Parameter Unity Natural gas Biogas Inlet temperature ºC 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 Numerical settings Grid: and 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

19 Combustion Chamber Results NG Premixed Flame Recirculation details Velocity distribution

20 Combustion Chamber Results NG Premixed Flame Mc=0,06 kg/s T = 664ºC Temperature profiles

21 Combustion Chamber Results NG Premixed Flame Mc=0,1 kg/s T = 852ºC Temperature profiles

22 Combustion Chamber Results Biogas Premixed Flame Mc=0,16 kg/s T = 1075ºC Temperature profiles

23 Combustion Chamber Results NG Diffuse Flame Velocity distribution

24 Combustion Chamber Results NG Diffuse Flame Mc=0,06 kg/s T = 718ºC Temperature profiles

25 Combustion Chamber Results GN Diffuse Flame Mc=0,1 kg/s T = 841ºC Temperature profiles

26 Combustion Chamber Results Biogas Diffuse Flame Mc=0,16 kg/s T = 1063ºC Temperature profiles

27 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.

28 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.

29 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.

30 - The mass flow provided by the Gatecycle GE Enter Sofware was based on simplified combustion models, assessed at stoichiometric condition Federal University of Itajubá Thanks for your attention!!!

31 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