Performance analysis of a twin shaft Industrial Gas Turbine at fouling conditions

In this study, the performance of a twin-shaft Industrial Gas Turbine (IGT) at fouling conditions is simulated through a Simulink model based on fundamental thermodynamics. Engine measurements across a twin-shaft IGT system during compressor fouling conditions were considered to validate this study. By implementing correlation coefficients in the compressor model, it is possible to predict the performance of the IGT system during compressor fouling conditions. The change of compressor air flow and the compressor efficiency in the twin-shaft IGT during fouling conditions is estimated. The results show that the reduction of air flow rate is the dominating parameter in the decrease of power generation in an IGT under fouled conditions. The model can provide an insight into the effect of compressor fouling conditions on system IGT performance

Performance analysis and prediction of compressor fouling condition for a twin-shaft engine

Performance of a twin-shaft Industrial Gas Turbine (IGT) at fouling condition is simulated via a gas turbine model based on fundamental thermodynamics. Measurements across the engine during compressor fouling conditions were considered to validate the outcomes. By implementing correlation coefficients in the compressor model, the performance of the IGT during compressor fouling conditions is predicted. The change in the compressor air flow and the compressor efficiency during fouling conditions is estimated. The results show that the reduction of air flow rate is the dominating parameter in loss of generated power under fouled conditions. The model can provide an insight into the effect of compressor fouling conditions on IGT performance

A thermodynamic transient model for performance analysis of a twin shaft Industrial Gas Turbine

In this study, a Simulink model based on fundamental thermodynamic principles to predict the dynamic and steady state performance in a twin shaft Industrial Gas Turbine (IGT) has been developed. The components comprising the IGT have been implemented in the modelling architecture using a thermodynamic commercial toolbox (Thermolib, EUtech Scientific Engineering GmbH) and Simulink environment. Measured air pressure and air temperature discharged by compressor allowed the validation of the modelling architecture. The model assisted the development of a computational tool based on Artificial Neural Network (ANN) for compressor fault diagnostics in IGTs. It has been demonstrated that modelling plays an important role to predict and monitor gas turbine system performance at different operating and ambient conditions

Performance-based health monitoring, diagnostics and prognostics for condition-based maintenance of gas turbines: A review

With the privatization and intense competition that characterize the volatile energy sector, the gas turbine industry currently faces new challenges of increasing operational flexibility, reducing operating costs, improving reliability and availability while mitigating the environmental impact. In this complex, changing sector, the gas turbine community could address a set of these challenges by further development of high fidelity, more accurate and computationally efficient engine health assessment, diagnostic and prognostic systems. Recent studies have shown that engine gas-path performance monitoring still remains the cornerstone for making informed decisions in operation and maintenance of gas turbines. This paper offers a systematic review of recently developed engine performance monitoring, diagnostic and prognostic techniques. The inception of performance monitoring and its evolution over time, techniques used to establish a high-quality dataset using engine model performance adaptation, and effects of computationally intelligent techniques on promoting the implementation of engine fault diagnosis are reviewed. Moreover, recent developments in prognostics techniques designed to enhance the maintenance decision-making scheme and main causes of gas turbine performance deterioration are discussed to facilitate the fault identification module. The article aims to organize, evaluate and identify patterns and trends in the literature as well as recognize research gaps and recommend new research areas in the field of gas turbine performance-based monitoring. The presented insightful concepts provide experts, students or novice researchers and decision-makers working in the area of gas turbine engines with the state of the art for performance-based condition monitoring

Gas Path Fault and Degradation Modelling in Twin-Shaft Gas Turbines

In this study, an assessment of degradation and failure modes in the gas-path components of twin-shaft industrial gas turbines (IGTs) has been carried out through a model-based analysis. Measurements from twin-shaft IGTs operated in the field and denoting reduction in engine performance attributed to compressor fouling conditions, hot-end blade turbine damage, and failure in the variable stator guide vane (VSGV) mechanism of the compressor have been considered for the analysis. The measurements were compared with simulated data from a thermodynamic model constructed in a Simulink environment, which predicts the physical parameters (pressure and temperature) across the different stations of the IGT. The model predicts engine health parameters, e.g., component efficiencies and flow capacities, which are not available in the engine field data. The results show that it is possible to simulate the change in physical parameters across the IGT during degradation and failure in the components by varying component efficiencies and flow capacities during IGT simulation. The results also demonstrate that the model can predict the measured field data attributed to failure in the gas-path components of twin-shaft IGTs. The estimated health parameters during degradation or failure in the gas-path components can assist the development of health-index prognostic methods for operational engine performance prediction

Performance based diagnostics of a twin shaft aeroderivative gas turbine: water wash scheduling

Aeroderivative gas turbines are used all over the world for different applications as Combined Heat and Power (CHP), Oil and Gas, ship propulsion and others. They combine flexibility with high efficiencies, low weight and small footprint, making them attractive where power density is paramount as off shore Oil and Gas or ship propulsion. In Western Europe they are widely used in CHP small and medium applications thanks to their maintainability and efficiency. Reliability, Availability and Performance are key parameters when considering plant operation and maintenance. The accurate diagnose of Performance is fundamental for the plant economics and maintenance planning. There has been a lot of work around units like the LM2500® , a gas generator with an aerodynamically coupled gas turbine, but nothing has been found by the author for the LM6000® . Water wash, both on line or off line, is an important maintenance practice impacting Reliability, Availability and Performance. This Thesis aims to select and apply a suitable diagnostic technique to help establishing the schedule for off line water wash on a specific model of this engine type. After a revision of Diagnostic Methods Artificial Neural Network (ANN) has been chosen as diagnostic tool. There was no WebEngine model available of the unit under study so the first step of setting the tool has been creating it. The last step has been testing of ANN as a suitable diagnostic tool. Several have been configured, trained and tested and one has been chosen based on its slightly better response. Finally, conclusions are discussed and recommendations for further work laid out

Impact of inlet filter pressure loss on single and two-spool gas turbine engines for different control modes

Inlet filtration systems are designed to protect industrial gas turbines from air borne particles and foreign objects, thereby improving the quality of air for combustion and reducing component fouling. Filtration systems are of varying grades and capture efficiencies, with the higher efficiency systems filters providing better protection but higher pressure losses. For the first time, two gas turbine engine models of different configurations and capacities have been investigated for two modes of operation (constant turbine entry temperature (TET) and load/power) for a two- and three-stage filter system. The main purpose of this is to present an account on factors that could decide the selection of filtration systems by gas turbine operators, solely based on performance. The result demonstrates that the two-spool engine is only slightly more sensitive to intake pressure loss relative to the single-spool. This is attributed to higher pressure ratio of the two-spool as well as the deceleration of the high pressure compressor (HPC)/high pressure turbine (HPT) shaft rotational speed in a constant TET operation. The compressor of the single-spool engine and the low pressure compressor (LPC) of the two-spool shows similar behavior: slight increase in pressure ratio and reduced surge margin at their constant rotational speed operation. Loss in shaft power is observed for both engines, about 2.5% at 1000 Pa loss. For constant power operation there is an increase in fuel flow and TET, and as a result the creep life was estimated. The result obtained indicates earlier operating hours to failure for the three-stage system over the two-stage by only a few thousand hours. However, this excludes any degradation due to fouling that is expected to be more significant in the two-stage system

Aero engine compressor fouling effects for short- and long-haul missions

The impact of compressor fouling on civil aero engines unlike the industrial stationary application has not been widely investigated or available in open literature. There are questions about the impact of fouling for short- and long-haul missions comparatively, given their unique operational requirements and market. The aim of this study is to quantify the effects of different levels of fouling degradation on the fan, for two different aircraft with different two-spool engine models for their respective typical missions. Firstly, the study shows the increase in turbine entry temperature for both aircraft engines, to maintain the same level of thrust as their clean condition. The highest penalty observed is during take-off and climb, when the thrust setting is the highest. Despite take-off and climb segment being a larger proportion in the short-haul mission compared to the long-haul mission, the percentage increase in fuel burn due to fouling are similar, except in the worst case fouling level were the former is higher by 0.8% points. In addition to this, for all the cases, the additional fuel burn due to fouling and its cost is shown to be small. Likewise, the increase in turbine entry temperature for both missions at take-off are similar, except in the worst case fouling level for the short-haul mission were the turbine entry temperature is 7 K higher than the corresponding long-haul mission for the same level of degradation. The study infers that the penalty due to rise in temperature is of more concern than the additional fuel burn. Hence the blade technology (cooling and material) and engine thrust rating are key factors in determining the extent to which blade fouling would affect aero engine performance in short- and long-haul missions

Inter-Stage Dynamic Performance of an Axial Compressor of a Twin-Shaft Industrial Gas Turbine

In this study, the inter-stage dynamic performance of a multistage axial compressor is simulated through a semi-empirical model constructed in the Matlab Simulink environment. A semi-empirical 1-D compressor model developed in a previous study has been integrated with a 0-D twin-shaft gas turbine model developed in the Simulink environment. Inter-stage performance data generated through a high-fidelity design tool and based on throughflow analysis are considered for the development of the inter-stage modeling framework. Inter-stage performance data comprise pressure ratio at various speeds with nominal variable stator guide vane (VGV) positions and with hypothetical offsets to them with respect to the gas generator speed (GGS). Compressor discharge pressure, fuel flow demand, GGS and power turbine speed measured during the operation of a twin-shaft industrial gas turbine are considered for the dynamic model validation. The dynamic performance of the axial-compressor, simulated by the developed modeling framework, is represented on the overall compressor map and individual stage characteristic maps. The effect of extracting air through the bleed port in the engine center-casing on transient performance represented on overall compressor map and stage performance maps is also presented. In addition, the dynamic performance of the axial-compressor with an offset in VGV position is represented on the overall compressor map and individual stage characteristic maps. The study couples the fundamental principles of axial compressors and a semi-empirical modeling architecture in a complementary manner. The developed modeling framework can provide a deeper understanding of the factors that affect the dynamic performance of axial compressors

Gas Turbine Performance and Maintenance

TutorialProper maintenance and operating practices can significantly affect the level of performance degradation and thus, time between repairs or overhauls of a gas turbine. Understanding of performance characteristics of gas turbines helps proper applications, as well as driven and process equipment sizing. Proactive condition monitoring will allow the gas turbine operator to make intelligent service decisions based on the actual condition of the gas turbine rather than on fixed and calendar based maintenance intervals. Maintaining inlet air, fuel, and lube oil quality will further reduce gas turbine degradation and deterioration. This tutorial provides a discussion on performance characteristics and how performance degradation can be minimized. Recommendations are provided on how the operator can limit degradation and deterioration of the gas turbines through proper maintenance practices. The effects of water-washing and best washing practices are discussed. Emphasis is on the monitoring of gas turbine performance parameters to establish condition based maintenance practices