The Development of High Performance Leaf Seals

2002 ◽  
Author(s):  
H. Nakane ◽  
A. Maekawa ◽  
E. Akita ◽  
K. Akagi ◽  
T. Shinohara ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Combined Cycle ◽  
Differential Pressure ◽  
Superior Performance ◽  
Hydrodynamic Effect ◽  
Air Leakage ◽  
Brush Seal ◽  
Sealing Performance ◽  
Performance Reduction ◽  
Secondary Air

Recently, from the environmental point of view, demand for combined cycle plant is increasing, and superior gas turbine performance is being rapidly promoted at the same time. As one of the key technologies for superior performance, reduction of secondary air leakage which is necessary for blade cooling and bearing sealing is required. Especially, reduction of air leakage through rotating parts and stationary parts clearance is critical problem. Hitherto, a non-contact type labyrinth seal has been widely used as a seal between rotating parts and stationary parts. However, this seal requires a large clearance to avoid contact, and this causes reduction of performance due to large amount of air leakage. Currently, application of brush seal is rapidly increasing as an improvement, however, a brush seal maintains contact not only at shut down, but also during operation, thereby wear of wire is accelerated during prolong operation, and reducing the sealing performance. In addition, since stiffness of the wire itself is low, differential sealing pressure is also low. In order to overcome these short comings, so-called “Leaf seal” which is MHI’s patent has been developed over the years. Leaf seal has a structure in which multi layered flexible leaves are arranged in the circumferential direction. In this seal, tip of the leaf is lifted up from the rotor surface by the hydrodynamic effect as the rotating speed is accelerated. As a result of this mechanism, wear of the seal is reduced during operation. The clearance generated by the leaf tip lifting up is negligibly small and, therefore, sealing performance is better. Moreover, because the leaf has an axial width, it can endure seal differential pressure several times that of the brush seal. The effect of the leaf lifting up and the leakage air amount were verified by rig tests. After these verification tests, this leaf seal is now being used for M501G gas turbine, installed at *T-point, in order to confirm sealing performance and durability. The leaf seal can sustain high differential pressure even if it is used in single stage, and has very good durability. To conclude it can be said that the leaf seal is the next generation seal replacing the brush seal. * MHI constructed the long-term in-house verification plant known as T-point for verifying new gas turbine technology prior to commercialization. The facility at T-Point consists of a M501G gas turbine, steam turbine, HRSG and associated controls. The output of the M501G gas turbine at T-Point is 225MW.

The Development of High-Performance Leaf Seals

2004 ◽  
Vol 126 (2) ◽  
pp. 342-350 ◽  
Author(s):  
H. Nakane ◽  
A. Maekawa ◽  
E. Akita ◽  
K. Akagi ◽  
T. Nakano ◽  
...  
Keyword(s):  
High Performance ◽  
Combined Cycle ◽  
Point Of View ◽  
Superior Performance ◽  
Air Leakage ◽  
Blade Cooling ◽  
Turbine Performance ◽  
Performance Reduction ◽  
Combined Cycle Plant ◽  
Secondary Air

Recently, from the environmental point of view, demand for a combined cycle plant is increasing, and superior gas turbine performance is being rapidly promoted at the same time. As one of the key technologies for superior performance, reduction of secondary air leakage, which is necessary for blade cooling and bearing sealing, is required. Especially, reduction of air leakage through rotating parts and stationary parts clearance is critical.

Compressor Discharge Brush Seal for Gas Turbine Model 7EA

2001 ◽  
Author(s):  
Steve Ingistov
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Unit ◽  
Labyrinth Seal ◽  
Compressed Air ◽  
Air Leakage ◽  
Heavy Duty ◽  
Gas Turbine Unit ◽  
Brush Seal ◽  
Industrial Gas Turbines

Single shaft-heavy-duty- industrial gas turbines are extremely sensitive to compressed air bypassing at compressor discharge plane. This plane represents the highest pressure location in entire Gas Turbine Unit (GTU). Standard method to minimize compressed air leakage is labyrinth seal that is integral part of the cylindrical element here called “inner barrel”. The “inner barrel” is also the part of compressor discharge diffuser. This Paper describes the efforts related to conversion of standard labyrinth seal into the hybrid seal that is combination of labyrinth and brush seals.

Using Fuzzy Logic to Control Combined Cycle Gas Turbine During Ambient Computing Environment

2020 ◽  
Vol 11 (3) ◽  
pp. 106-130 ◽  
Author(s):  
Mostafa A. Elhosseini
Keyword(s):  
Fuzzy Logic ◽  
Gas Turbine ◽  
Fuzzy Inference ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Superior Performance ◽  
Rule Base ◽  
Computing Environment ◽  
Inference System ◽  
Ambient Computing

The main aim of this article is to analyse and control a combined cycle gas turbine (CCGT) under normal and perturbation loading using a Fuzzy Logic Control (FLC) and an Adaptive Neuro-Fuzzy Inference System (ANFIS) through an ambient computing environment. The main characteristics of ambient computing is invisible, embedded, easy to use, and adaptive to name a few. The current article proposes the employment of FLC and to control the operation of CCGT considering the system inputs uncertainty. The target of the FLC is to maintain the system speed, exhaust temperature, and airflow within the desired interval. ANFIS helps to get the optimal control parameter and construct the proper rule base with an appropriate membership function with reasonable accuracy. The simulation results demonstrate the ANFIS controller's superior performance over FLC as well as the traditional controller for normal operating conditions and load perturbation.

Numerical and Experimental Investigation of Secondary Flows and Influence of Air System Design on Heavy-Duty Gas Turbine Performance

2012 ◽  
Author(s):  
Luca Bozzi ◽  
Enrico D’angelo
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Combined Cycle ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Heavy Duty ◽  
Turbine Performance ◽  
Air System ◽  
Secondary Air

High turn-down operating of heavy-duty gas turbines in modern Combined Cycle Plants requires a highly efficient secondary air system to ensure the proper supply of cooling and sealing air. Thus, accurate performance prediction of secondary flows in the complete range of operating conditions is crucial. The paper gives an overview of the secondary air system of Ansaldo F-class AEx4.3A gas turbines. Focus of the work is a procedure to calculate the cooling flows, which allows investigating both the interaction between cooled rows and additional secondary flows (sealing and leakage air) and the influence on gas turbine performance. The procedure is based on a fluid-network solver modelling the engine secondary air system. Parametric curves implemented into the network model give the consumption of cooling air of blades and vanes. Performances of blade cooling systems based on different cooling technology are presented. Variations of secondary air flows in function of load and/or ambient conditions are discussed and justified. The effect of secondary air reduction is investigated in details showing the relationship between the position, along the gas path, of the upgrade and the increasing of engine performance. In particular, a section of the paper describes the application of a consistent and straightforward technique, based on an exergy analysis, to estimate the effect of major modifications to the air system on overall engine performance. A set of models for the different factors of cooling loss is presented and sample calculations are used to illustrate the splitting and magnitude of losses. Field data, referred to AE64.3A gas turbine, are used to calibrate the correlation method and to enhance the structure of the lumped-parameters network models.

Effect of Rim Seal Configuration on Gas Turbine Cavity Sealing in Both Design and Off-Design Conditions

2018 ◽  
Author(s):  
Riccardo Da Soghe ◽  
Cosimo Bianchini ◽  
Mirko Micio ◽  
Jacopo D’Errico ◽  
Francesco Bavassano
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Acoustic Mode ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Turbine Wheel ◽  
Sealing Performance ◽  
Secondary Air ◽  
Heavy Duty Gas Turbine

The desired reduction of secondary air consumption of gas turbines is especially challenging when the sealing of stator-rotor cavities is concerned, where it is necessary to guarantee integrity against hot gas ingestion. Sealing and thermal performance of gas turbine stator-rotor cavities are directly dependent on the rim configuration. This paper provides a CFD-based characterization of heavy-duty gas turbine wheel-spaces when dealing with real engine operating conditions and geometries. Focusing on the rim seal configuration, the geometrical arrangement of the ingestion-cavity, the buffer-cavity and the inner cavities were investigated to improve the ingress flow-discouraging behaviour. The study reveals that the most important geometrical parameters affecting the rim sealing effectiveness are those related to the ingestion-cavity. Moreover, an empirical model to predict the stator-rotor cavity sealing performance in off-design conditions was proposed. The model, that consists in an extension of a well-known literature approach, performed well at the analysed operating conditions, confirming to be an excellent tool for the early design phases. Finally, an investigation on the unsteady behaviour of the seal highlights a coupling with an acoustic mode of the cavity, suggesting possible reasons to justify the presence of rotating structures embedded into the cavity flow.

Compressor Discharge Brush Seal for Gas Turbine Model 7EA

2002 ◽  
Vol 124 (2) ◽  
pp. 301-305 ◽  
Author(s):  
Steve Ingistov
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Unit ◽  
Labyrinth Seal ◽  
Compressed Air ◽  
Air Leakage ◽  
Heavy Duty ◽  
Gas Turbine Unit ◽  
Brush Seal ◽  
Industrial Gas Turbines

Single-shaft, heavy-duty industrial gas turbines are extremely sensitive to compressed air bypassing at compressor discharge plane. This plane represents the highest pressure location in entire gas turbine unit (GTU). Standard method to minimize compressed air leakage is labyrinth seal that is integral part of the cylindrical element here called “inner barrel.” The inner barrel is also the part of compressor discharge diffuser. This paper describes the efforts related to conversion of standard labyrinth seal into the hybrid seal that is combination of labyrinth and brush seals.

Reaction of Fuel NOx Formation for Gas Turbine Conditions

1998 ◽  
Vol 120 (3) ◽  
pp. 474-480 ◽  
Author(s):  
T. Nakata ◽  
M. Sato ◽  
T. Hasegawa
Keyword(s):  
Gas Turbine ◽  
Coal Gasification ◽  
Combustion Process ◽  
Combined Cycle ◽  
Inlet Section ◽  
Mixing Condition ◽  
Nox Formation ◽  
Air Inlet ◽  
Secondary Air ◽  
Fuel Nox

Ammonia contained in coal-gasified fuel is converted to nitrogen oxides (NOx) in the combustion process of a gas turbine in integrated coal gasification combined cycle (IGCC) system. Research data on fuel-NOx formation are insufficient, and there still remains a wide explored domain. The present research aims at obtaining fundamental knowledge of fuel-NOx formation characteristics by applying reaction kinetics to gas turbine conditions. An instantaneous mixing condition was assumed in the cross section of a gas turbine combustor and both gradual mixing condition and instantaneous mixing condition were assumed at secondary air inlet section. The results may be summarized as follows: (1) in the primary combustion zone under fuel rich condition, HCN and other intermediate products are formed as ammonia contained in the fuel decomposes; (2) formation characteristics of fuel-NOx are affected by the condition of secondary air mixing; and (3) the conversion ratio from ammonia to NOx declines as the pressure inside the combustor rises under the condition of gradual mixing at the secondary air inlet. These results obtained agreed approximately with the experimentation.

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.

Tradeoff Assessments for Part Load Controlled Cooling Air in Stationary Gas Turbines

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Dominik Woelki ◽  
Dieter Peitsch
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Coupled Model ◽  
Combined Cycle ◽  
Controlled Cooling ◽  
Part Load ◽  
Air System ◽  
Secondary Air ◽  
Cooling Air ◽  
Operating Points

Abstract The demand for flexible part load operation of stationary gas turbines requires the simultaneous design for sufficient efficiency and lifetime. Both can be addressed by the secondary air system. This paper presents investigations on the concepts of cooling air reduction in off-design, aiming for tradeoffs between fuel burn and turbine blade life. The considered lifetime mechanisms are creep and oxidation. In addition, the effects on emissions from the combustion are outlined. The reference gas turbine is a generic gas turbine in the 300 MW power output segment. The focus is on the first two stages of the four-stage turbine. All simulations are performed by application of a coupled model that essentially connects gas turbine performance with a secondary air system network model. This coupled model is now extended with blade life evaluation and emission models. The results contain tradeoffs for operating points at base and part load. For example, the combined cooling air control of stage 1 rotor blade and stage 2 vane offers savings up to 0.5% fuel flow at 60% of base load in a combined cycle application. This saving is at the expense of creep life. However, some operating points could even operate at higher blade temperatures in order to improve life regarding hot corrosion. Furthermore, generic sensitivities of controlled secondary air supply to cooling layers and hot gas ingestion are discussed. Overall, the presented trades mark promising potentials of modulated secondary air system concepts from a technical point of view.

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.

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