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.

3-Dimensional Pressure Driven Temperature Field in a Gas Turbine Combustion Chamber

2006 ◽  
Author(s):  
Fernando Z. Sierra ◽  
Areli Uribe ◽  
Janusz Kubiak ◽  
Hugo Lara ◽  
Gustavo Urquiza ◽  
...  
Keyword(s):  
Temperature Field ◽  
Steady State ◽  
Temperature Distribution ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Air Flow ◽  
Combined Cycle ◽  
3 Dimensional ◽  
Gas Fuel ◽  
Gas Turbine Combustion

In this work the temperature field in a gas turbine combustion chamber is investigated through numerical computations. The combustion chamber under study is part of a 70 MW gas turbine from an operating combined cycle power plant. The simulation of combustion and flow dynamics is fully 3-dimensional. It addresses complex turbulence structure and temperature distribution inside the combustion chamber. The swirling effect is taken into account using a detailed gas-fuel-air mixing swirler. The combustion was simulated with proper gas-fuel-air flow ratio assuming stoichiometric equilibrium conditions. Based on previous results, pressure imbalance conditions of air flow between primary and secondary inlets is used to perturb the temperature distribution. In this work, a periodic function was used to produce pressure variation in the air flow, which in turn alter the temperature field and turbulence structures. First, characteristic temperature and pressure fields were obtained using steady state boundary conditions. The steady state solutions were perturbed using a periodic boundary condition (6 kPa per short periods of time) resulting in different results. The results are discussed and confirm previous 2-dimesional computations where excessive heating in regions other than the combustion chamber core occurred. The investigation is aimed to explain why overheating occurs, since it causes burning out of pipe materials, producing permanent damage to auxiliary cross flame pipes.

A Study on Low NOx Combustion in LBG-Fueled 1500°C-Class Gas Turbine

1994 ◽  
Author(s):  
Toshihiko Nakata ◽  
Mikio Sato ◽  
Toru Ninomiya ◽  
Takeharu Hasegawa
Keyword(s):  
Power Generation ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Coal Gasification ◽  
Combustion Process ◽  
Combined Cycle ◽  
Inlet Temperature ◽  
Gas Temperature ◽  
Secondary Air

Developing integrated coal gasification combined cycle systems ensures cost-effective and environmentally sound options for supplying future power generation needs. The reduction of NOx emissions and increasing the inlet temperature of gas turbines are the most significant issues in gas turbine development in an Integrated Coal Gasification Combined Cycle (IGCC) power generation systems. The coal gasified fuel, which is produced in a coal gasifier of air-blown entrained-flow type has calorific value as low as 1/10 of natural gas. Furthermore the fuel gas contains ammonia when a gas cleaning system is a hot type, and ammonia will be converted to nitrogen oxides in the combustion process of a gas turbine. This study is performed in a 1500°C-class gas turbine combustor firing low-Btu coal-gasified fuel in IGCC systems. An advanced rich-lean combustor of 150-MW class gas turbine was designed to hold stable combustion burning low-Btu gas and to reduce fuel NOx emission that is produced from the ammonia in the fuel. The main fuel and the combustion air is supplied into fuel-rich combustion chamber with strong swirl flow and make fuel-rich flame to decompose ammonia into intermediate reactants such as NHi and HCN. The secondary air is mixed with primary combustion gas dilatorily to suppress the oxidization of ammonia reactants in fuel-lean combustion chamber and to promote a reducing process to nitrogen. By testing it under atmospheric pressure conditions, the authors have obtained a very significant result through investigating the effect of combustor exit gas temperature on combustion characteristics. Since we have ascertained the excellent performance of the tested combustor through our extensive investigation, we wish to report on the results.

Siemens SGT-800 Industrial Gas Turbine Enhanced to 50MW: Combustor Design Modifications, Validation and Operation Experience

2013 ◽  
Author(s):  
Daniel Lörstad ◽  
Annika Lindholm ◽  
Jan Pettersson ◽  
Mats Björkman ◽  
Ingvar Hultmark
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Cooling System ◽  
Good Condition ◽  
Combined Cycle ◽  
Combustion Stability ◽  
Combustion System ◽  
Design Work ◽  
Engine Operation ◽  
Cooling Air

Siemens Oil & Gas introduced an enhanced SGT-800 gas turbine during 2010. The new power rating is 50.5MW at a 38.3% electrical efficiency in simple cycle (ISO) and best in class combined-cycle performance of more than 55%, for improved fuel flexibility at low emissions. The updated components in the gas turbine are interchangeable from the existing 47MW rating. The increased power and improved efficiency are mainly obtained by improved compressor airfoil profiles and improved turbine aerodynamics and cooling air layout. The current paper is focused on the design modifications of the combustor parts and the combustion validation and operation experience. The serial cooling system of the annular combustion chamber is improved using aerodynamically shaped liner cooling air inlet and reduced liner rib height to minimize the pressure drop and optimize the cooling layout to improve the life due to engine operation hours. The cold parts of the combustion chamber were redesigned using cast cooling struts where the variable thickness was optimized to maximize the cycle life. Due to fewer thicker vanes of the turbine stage #1, the combustor-turbine interface is accordingly updated to maintain the life requirements due to the upstream effect of the stronger pressure gradient. Minor burner tuning is used which in combination with the previously introduced combustor passive damping results in low emissions for >50% load, which is insensitive to ambient conditions. The combustion system has shown excellent combustion stability properties, such as to rapid load changes and large flame temperature range at high loads, which leads to the possibility of single digit Dry Low Emission (DLE) NOx. The combustion system has also shown insensitivity to fuels of large content of hydrogen, different hydrocarbons, inerts and CO. Also DLE liquid operation shows low emissions for 50–100% load. The first SGT-800 with 50.5MW rating was successfully tested during the Spring 2010 and the expected performance figures were confirmed. The fleet leader has, up to January 2013, accumulated >16000 Equivalent Operation Hours (EOH) and a planned follow up inspection made after 10000 EOH by boroscope of the hot section showed that the combustor was in good condition. This paper presents some details of the design work carried out during the development of the combustor design enhancement and the combustion operation experience from the first units.

Actuation Studies for Active Control of Mild Combustion for Gas Turbine Application

2014 ◽  
Author(s):  
Emilien Varea ◽  
Stephan Kruse ◽  
Heinz Pitsch ◽  
Thivaharan Albin ◽  
Dirk Abel
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Active Control ◽  
Gas Turbines ◽  
Reverse Flow ◽  
Air Flow ◽  
Combustion Regime ◽  
Nox Emissions ◽  
Low Oxygen ◽  
Mild Combustion

MILD combustion (Moderate or Intense Low Oxygen Dilution) is a well known technique that can substantially reduce high temperature regions in burners and thereby reduce thermal NOx emissions. This technology has been successfully applied to conventional furnace systems and seems to be an auspicious concept for reducing NOx and CO emissions in stationary gas turbines. To achieve a flameless combustion regime, fast mixing of recirculated burnt gases with fresh air and fuel in the combustion chamber is needed. In the present study, the combustor concept is based on the reverse flow configuration with two concentrically arranged nozzles for fuel and air injections. The present work deals with the active control of MILD combustion for gas turbine applications. For this purpose, a new concept of air flow rate pulsation is introduced. The pulsating unit offers the possibility to vary the inlet pressure conditions with a high degree of freedom: amplitude, frequency and waveform. The influence of air flow pulsation on MILD combustion is analyzed in terms of NOx and CO emissions. Results under atmospheric pressure show a drastic decrease of NOx emissions, up to 55%, when the pulsating unit is active. CO emissions are maintained at a very low level so that flame extinction is not observed. To get more insights into the effects of pulsation on combustion characteristics, velocity fields in cold flow conditions are investigated. Results show a large radial transfer of flow when pulsation is activated, hence enhancing the mixing process. The flame behavior is analyzed by using OH* chemiluminescence. Images show a larger distributed reaction region over the combustion chamber for pulsation conditions, confirming the hypothesis of a better mixing between fresh and burnt gases.

Investigation of the Prediction Correlations for the Flow Through Rotating Orifices in the Gas Turbine Secondary Air Flow System

2013 ◽  
Author(s):  
Deoras Prabhudharwadkar ◽  
Zain Dweik ◽  
A. Subramani ◽  
Murali Krishnan R.
Keyword(s):  
Gas Turbine ◽  
Discharge Coefficient ◽  
Flow System ◽  
Air Flow ◽  
Tangential Velocity ◽  
Cross Flow ◽  
Secondary System ◽  
Accurate Analysis ◽  
Secondary Air ◽  
Reliable Design

The secondary air flow system of a gas turbine cools and seals those parts of the turbine which would otherwise be exposed to the high temperatures, resulting in their life reduction or even failures. At the same time, excessive secondary air flow hinders the performance of the engine. Accurate analysis of the secondary system is therefore necessary to safeguard the reliable design of the engine and accurate life predictions. The secondary system is analyzed through the flow network analysis which comprises of chambers or cavities connected through flow passages or restrictions. There are significant number of locations where the air passes through stationary or rotating holes, e.g., the pre-swirl nozzles and the turbine blade receiver holes respectively. The accuracy of the flow prediction depends on the accuracy of the orifice discharge coefficient. This paper provides a detailed assessment of the available discharge coefficient correlations. The discharge coefficient has been found to be dependent on the geometric parameters (viz., length, inlet radius, chamfer), and the amount of cross-flow at the orifice entrance. The cross-flow may result from the relative tangential velocity between the orifice and the air or the inclination of the inlet flow with respect to the orifice axis. In this study, it was found that the discharge coefficient correlations provide similar predictions for flows without any cross-flow. However, significant deviations are seen in the predictions for the cases involving cross-flow. To identify the most accurate correlation for secondary flow application, a thorough assessment was performed using the static and the rotating test data available in the literature. In addition to the comparison using available experimental data, a CFD study was performed to independently assess the correlations. This exercise led to the identification of the most suitable correlation for our application.

scholarly journals Research on GTE-110 gas turbine operating modes for limiting nitrogen oxide emissions of ccgt power units

Vestnik IGEU ◽  
2020 ◽  
pp. 11-21
Author(s):  
I.K. Muravev ◽  
A.B. Korovkin ◽  
R.A. Shitov
Keyword(s):  
Nitrogen Oxides ◽  
Simulation Model ◽  
Combustion Chamber ◽  
Nitrogen Oxide ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Climatic Factors ◽  
Combined Cycle ◽  
Nitrogen Oxide Emissions ◽  
Excess Air

Gas turbines are actively used as a part of combined-cycle power units having less impact on the environ-ment than installations operating on other types of fuel. However, their emissions contain harmful carbon compounds and nitrogen oxides. Some research studies considered the effect of emissions upon changes in the coefficient of excess air. At the same time, no attention was paid to the influence of other operational parameters and technological limitations associated with the safe operation of combined-cycle CCGT equipment, and no assessment was made of the impact of climatic factors on environmental indicators. Thus, it is important to conduct separate studies to assess the influence of regime and climatic factors on the stability of the combustion process in the combustion chamber of a gas turbine, on the environmental performance of the installation and the compliance of these indicators with the standards. The research used data from the control system archive, and a simulation model was developed in the SimInTech environment. The following assumptions are made in the model: the fuel composition does not change and it enters the single combustion zone without separation into the pilot and central zones of the combustion chamber. The methodology for calculating emissions is reduced to dividing their volume into NO and NO2 due to the transformation of nitrogen oxides in the air. Subsequently, the values of the total concentration are recalculated to a single NOx value. A simulation model for calculating emissions has been obtained. The effect of excess air on nitrogen oxide emissions considering the technological zones of gas turbines of outdoor air temperature (To.a) from –20 to +30 оС and the power from 48 to 110 MW has been assessed. It has been shown that near the nominal load the maximum NOx emission are observed. In general, the results obtained indicate that the requirements for NOx emission standards are met in the entire operating range of gas turbine load changes. However, the reserve of a possible deviation of emissions to a critical level is only 10 %. The verification of the developed model is based on operational trends. The recommendations on operational management have been formulated for power unit operators in order to maintain an ac-ceptable level of NOx emissions.

Air supply system design of a Diesel–Brayton combined cycle engine

2018 ◽  
Vol 233 (4) ◽  
pp. 545-555
Author(s):  
Yuzhi Jin ◽  
Yuping Qian ◽  
Yangjun Zhang ◽  
Weilin Zhuge
Keyword(s):  
Diesel Engine ◽  
Combustion Chamber ◽  
Gas Turbine ◽  
Operation Mode ◽  
Three Dimensional ◽  
Engine Performance ◽  
Supply System ◽  
Combined Cycle ◽  
Air Supply ◽  
Startup Performance

The Diesel–Brayton combined cycle engine was proposed previously to achieve the goal of lower fuel consumption, higher power density and good startup performance under low-temperature conditions. The prototype engine was designed and tested based on an off-the-shelf gas turbine and a diesel engine. To achieve a more compact and lighter design, the air supply system was designed based on the centrifugal compressor of the gas turbine. In the coupling operation mode aiming to generate the maximum power, a large amount of compressed air must be extracted into the diesel engine. The present paper presents the design methodology of the compact air supply system. The bleeding slot configuration was selected based on a parametric study and proven by systematic experiments. Three-dimensional simulations were conducted to investigate the performance and flow field of the compressor. Backflow appeared in several passages of the axial diffuser caused by air bleeding, which further distorted the air flow in the combustion chamber. Such distortion may cause compressor and combustion instabilities. In the future, the combustion chamber and the axial diffuser must be designed in combination with an air bleeding system to improve the engine performance.

Evaluation of Advanced Combined Cycle Power Plants

1998 ◽  
Vol 212 (1) ◽  
pp. 1-12 ◽  
Author(s):  
C Kail
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Power Plants ◽  
Closed Loop ◽  
Cooling System ◽  
Turbine Blades ◽  
Combined Cycle ◽  
Steam Quality ◽  
Technical Problems ◽  
Steam Cooling

This report will analyse and evaluate the most recent and significant trends in combined cycle gas turbine (CCGT) power plant configurations. The various enhancements will be compared with the ‘simple’ gas turbine. The first trend, a gas turbine with reheat, cannot convert its better efficiency and higher output into a lower cost of electrical power. The additional investments required as well as increased maintenance costs will neutralize all the thermodynamic performance advantages. The second concept of cooling the turbine blades with steam puts very stringent requirements on the blade materials, the steam quality and the steam cooling system design. Closed-loop steam cooling of turbine blades offers cost advantages only if all its technical problems can be solved and the potential risks associated with the process can be eliminated through long demonstration programmes in the field. The third configuration, a gas turbine with a closed-loop combustion chamber cooling system, appears to be less problematic than the previous, steam-cooled turbine blades. In comparison with an open combustion chamber cooling system, this solution is more attractive due to better thermal performance and lower emissions. Either air or steam can be used as the cooling fluid.

Predicting Flashback Limits of a Gas Turbine Model Combustor Based on Velocity and Fuel Concentration for H2-Air-Mixtures

2016 ◽  
Author(s):  
Matthias Utschick ◽  
Daniel Eiringhaus ◽  
Christian Köhler ◽  
Thomas Sattelmayer
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
High Speed ◽  
Air Flow ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Fuel Injector ◽  
Trailing Edge ◽  
Fuel Concentration ◽  
Turbine Model

This study investigates the influence of the fuel injection strategy on safety against flashback in a gas turbine model combustor with premixing of H2-air-mixtures. The flashback propensity is quantified and the flashback mechanism is identified experimentally. The A2EV swirler concept exhibits a hollow, thick walled conical structure with four tangential slots. Four fuel injector geometries were tested. One of them injects the fuel orthogonal to the air flow in the slots (jet-in-crossflow-injector, JICI). Three injector types introduce the fuel almost isokinetic to the air flow at the trailing edge of the swirler slots (trailing edge injector, TEI). Velocity and mixing fields in mixing zone and combustion chamber in isothermal water flow were measured with High-speed-Particle-Image-Velocimetry (PIV) and Highspeed-Laser-Induced-Fluorescence (LIF). The flashback limit was determined under atmospheric pressure for three air mass flows and 673 K preheat temperature for H2-air-mixtures. Flashback mechanism and trajectory of the flame tip during flashback were identified with two stereoscopically oriented intensified high-speed cameras observing the OH* radiation. We notice flashback in the core flow due to Combustion Induced Vortex Breakdown (CIVB) and Turbulent upstream Flame Propagation (TFP) near the wall dependent on the injector type. The Flashback Resistance (FBR) defined as the ratio between a characteristic flow speed and a characteristic flame speed measures the direction of propagation of a turbulent flame in the flow field. Although CIVB cannot be predicted solely based on the FBR, its distribution gives evidence for CIVB-prone states. The fuel should be injected preferably isokinetic to the air flow along the entire trailing edge in oder to reduce the RMS fluctuation of velocity and fuel concentration. The characteristic velocity in the entire cross section of the combustion chamber inlet should be at least twice the characteristic flame speed. The position of the stagnation point should be tuned to be located in the combustion chamber by adjusting the axial momentum. Those measures lead to safe operation with highly reactive fuels at high equivalence ratios.

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