The emergency shutdown of a compressor train is a necessary safety feature. In this event, the power supply (either from a gas turbine or an electric motor) is cut off. The compressor train will continue to spin due to its inertia, but the speed will reduce fast. To avoid damage of the equipment during a shutdown event, compressor surge must to be avoided. In many instances, the dynamic behavior of the compression system is simulated to ensure that the necessary recycle valves are sized, and arranged properly. One of the key problems of dynamic simulation, and a major source of uncertainty in the results, is the correct treatment of the speed decay of the compressor train. The present study provides the background to evaluate the speed decay, and includes data from actual rundown situations. The evaluation shows general trends, that can be used to reduce the simulation uncertainties in dynamic simulations.
{"title":"Compressor Speed Decay During Emergency Shutdowns","authors":"R. Kurz, Garceau Sean, Min Ji, K. Brun","doi":"10.1115/gt2019-90020","DOIUrl":"https://doi.org/10.1115/gt2019-90020","url":null,"abstract":"\u0000 The emergency shutdown of a compressor train is a necessary safety feature. In this event, the power supply (either from a gas turbine or an electric motor) is cut off. The compressor train will continue to spin due to its inertia, but the speed will reduce fast. To avoid damage of the equipment during a shutdown event, compressor surge must to be avoided. In many instances, the dynamic behavior of the compression system is simulated to ensure that the necessary recycle valves are sized, and arranged properly. One of the key problems of dynamic simulation, and a major source of uncertainty in the results, is the correct treatment of the speed decay of the compressor train. The present study provides the background to evaluate the speed decay, and includes data from actual rundown situations. The evaluation shows general trends, that can be used to reduce the simulation uncertainties in dynamic simulations.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129847190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Minotti, A. Corsini, G. Delibra, G. Lucherini, S. Rossin, L. Tieghi, S. Traldi
Design of gas turbine packages is subjected to safety issues and the related guidelines are provided by ISO-21789. According to this code, the ventilation system shall guarantee a good and safe dilution in case of an unexpected gas leakage from components of the fuel gas system inside the enclosure. The evaluation of the dilution is commonly carried out by CFD simulations and the ISO-21789 indicates the criteria to evaluate the danger of a gas leak by estimating the cloud volume of the explosive mixture. To follow this prescription and to properly calculate the exact volume cloud, it is fundamental to accurately reproduce the fuel gas leak, which is always a supersonic jet of fuel gas into an air-ventilated domain. The main criticality is to simulate a supersonic jet into a complex domain such as the gas turbine package, considering the industrial goals in terms of accuracy and time constraints. The complexity is due to the geometry of the package and to the multiple locations where the leakage could occur. In such context, it is preferable to develop an advanced modeling of the phenomenon rather than simply improve the detail of the CFD, that could turn out to be unfeasible for industrial goals. For this reason, the authors present a series of simulations of under-expanded jets at high pressure ratios carried out to investigate the applicability of the sonic source approach to not-round jets.
{"title":"Modelling of Sonic Jets for Gas Leak Applications","authors":"S. Minotti, A. Corsini, G. Delibra, G. Lucherini, S. Rossin, L. Tieghi, S. Traldi","doi":"10.1115/gt2019-91199","DOIUrl":"https://doi.org/10.1115/gt2019-91199","url":null,"abstract":"\u0000 Design of gas turbine packages is subjected to safety issues and the related guidelines are provided by ISO-21789. According to this code, the ventilation system shall guarantee a good and safe dilution in case of an unexpected gas leakage from components of the fuel gas system inside the enclosure. The evaluation of the dilution is commonly carried out by CFD simulations and the ISO-21789 indicates the criteria to evaluate the danger of a gas leak by estimating the cloud volume of the explosive mixture. To follow this prescription and to properly calculate the exact volume cloud, it is fundamental to accurately reproduce the fuel gas leak, which is always a supersonic jet of fuel gas into an air-ventilated domain. The main criticality is to simulate a supersonic jet into a complex domain such as the gas turbine package, considering the industrial goals in terms of accuracy and time constraints. The complexity is due to the geometry of the package and to the multiple locations where the leakage could occur. In such context, it is preferable to develop an advanced modeling of the phenomenon rather than simply improve the detail of the CFD, that could turn out to be unfeasible for industrial goals.\u0000 For this reason, the authors present a series of simulations of under-expanded jets at high pressure ratios carried out to investigate the applicability of the sonic source approach to not-round jets.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133895085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Compression equipment used for industrial applications are typically comprised of multi-stage intercooled compressor stages. The presence of large volume intercoolers between individual stages adds a layer of complexity currently not present in publicly available surge models both in terms of system behavior and recovery analysis. In this work a compressible, temporal, and spatial model is developed in which the conservation equations are solved numerically for each of the system components, i.e. pipes, plenums and heat exchangers, valves, and individual compressor stages. The model can identify the onset of instability on an individual stage basis as well as the switching that can occur between the controlling stages of the instability onset when the operating conditions change, e.g. changes in inlet conditions, intercooler fouling or cooling tower performance reduction, and speed or guide vane changes. The model is therefore used both as a stage stacking model during the compressor stable operation as well as a model of the transient behavior of the system past the stable operation. An inertial model of the compressor drive train is also incorporated to analyze the effects of power transients, e.g. emergency shut down (ESD), on the system behavior. In this article details of the developed model are provided. Several test cases are presented. The model is then used to demonstrate the proper sizing of a vent valve of a base load compressor to meet the required system response specification in a surge event. The developed model represents an improvement over available transient system models in terms of predicting the post stable behavior of multi-stage intercooled compressors.
{"title":"A Model for System Instability Analysis in a Multi-Stage Intercooled Industrial Compressor","authors":"Jiaye Gan, A. Abdelwahab, V. Kilchyk","doi":"10.1115/gt2019-90098","DOIUrl":"https://doi.org/10.1115/gt2019-90098","url":null,"abstract":"\u0000 Compression equipment used for industrial applications are typically comprised of multi-stage intercooled compressor stages. The presence of large volume intercoolers between individual stages adds a layer of complexity currently not present in publicly available surge models both in terms of system behavior and recovery analysis. In this work a compressible, temporal, and spatial model is developed in which the conservation equations are solved numerically for each of the system components, i.e. pipes, plenums and heat exchangers, valves, and individual compressor stages. The model can identify the onset of instability on an individual stage basis as well as the switching that can occur between the controlling stages of the instability onset when the operating conditions change, e.g. changes in inlet conditions, intercooler fouling or cooling tower performance reduction, and speed or guide vane changes. The model is therefore used both as a stage stacking model during the compressor stable operation as well as a model of the transient behavior of the system past the stable operation. An inertial model of the compressor drive train is also incorporated to analyze the effects of power transients, e.g. emergency shut down (ESD), on the system behavior. In this article details of the developed model are provided. Several test cases are presented. The model is then used to demonstrate the proper sizing of a vent valve of a base load compressor to meet the required system response specification in a surge event. The developed model represents an improvement over available transient system models in terms of predicting the post stable behavior of multi-stage intercooled compressors.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133327606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Planetary gearbox is widely used in large and complex mechanical equipment such as wind power generation, helicopters and petrochemical industry. Gear failures occur frequently in working conditions at low speeds, high service load and harsh operating environments. Incipient fault diagnosis can avoid the occurrence of major accidents and loss of personnel property. Aiming at the problems that the incipient fault of planetary gearbox is difficult to recognize and the number of intrinsic mode functions (IMFs) decomposed by variational mode decomposition (VMD) must be set in advance and can not be adaptively selected, a improved VMD algorithm based on energy difference as an evaluation parameter to automatically determine the decomposition level k is proposed. On this basis, a new method for early fault feature extraction of planetary gearbox based on the improved VMD and frequency-weighted energy operator is proposed. Firstly, the vibration signal is pre-decomposed by VMD, and the energy difference between the component signal and the original signal under different K-values is calculated respectively. The optimal decomposition level k is determined according to the energy difference curve. Then, according to kurtosis criterion, sensitive components are selected from the k modal components obtained by the decomposition to reconstruct. Finally, a new frequency-weighted energy operator is used to demodulate the reconstructed signal. The fault characteristic frequency information of the planetary gearbox can be accurately extracted from the energy spectrum. The method is applied to the simulation fault data and actual data of planetary gearbox, and the weak fault characteristics of planetary gearbox are extracted effectively, and the early fault characteristics are distinguished. The results show that the new method has certain application value and practical significance.
{"title":"Incipient Fault Diagnosis of the Planetary Gearbox Based on Improved Variational Mode Decomposition and Frequency-Weighted Energy Operator","authors":"Hongkun Li, Chaoge Wang, Jiayu Ou","doi":"10.1115/gt2019-90572","DOIUrl":"https://doi.org/10.1115/gt2019-90572","url":null,"abstract":"\u0000 Planetary gearbox is widely used in large and complex mechanical equipment such as wind power generation, helicopters and petrochemical industry. Gear failures occur frequently in working conditions at low speeds, high service load and harsh operating environments. Incipient fault diagnosis can avoid the occurrence of major accidents and loss of personnel property. Aiming at the problems that the incipient fault of planetary gearbox is difficult to recognize and the number of intrinsic mode functions (IMFs) decomposed by variational mode decomposition (VMD) must be set in advance and can not be adaptively selected, a improved VMD algorithm based on energy difference as an evaluation parameter to automatically determine the decomposition level k is proposed. On this basis, a new method for early fault feature extraction of planetary gearbox based on the improved VMD and frequency-weighted energy operator is proposed. Firstly, the vibration signal is pre-decomposed by VMD, and the energy difference between the component signal and the original signal under different K-values is calculated respectively. The optimal decomposition level k is determined according to the energy difference curve. Then, according to kurtosis criterion, sensitive components are selected from the k modal components obtained by the decomposition to reconstruct. Finally, a new frequency-weighted energy operator is used to demodulate the reconstructed signal. The fault characteristic frequency information of the planetary gearbox can be accurately extracted from the energy spectrum. The method is applied to the simulation fault data and actual data of planetary gearbox, and the weak fault characteristics of planetary gearbox are extracted effectively, and the early fault characteristics are distinguished. The results show that the new method has certain application value and practical significance.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"117 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124101310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents the dynamic characterization of a two degree of freedom planetary gearbox prototype during the variation of the load condition. Tests with varying load are developed at three different operating speeds of the input shaft: 190, 380 and 590 rpm. The dynamic torques and vibrations on the input and output shafts are acquired during the experiments, such as the angular velocity of the output shaft. The experimental data are analyzed to evaluate the dynamics of the system during the exchange of operation between the first and second DOF operation. Then, the radial vibrations are analyzed during the operation of the second DOF by means of a methodology using different signal processing tools: first, the continuous wavelet transform is used to identify the nonlinear behavior and the main frequency content of the system; then, the vibrations are filtered by means of passband filters in order to keep the main frequencies of the system and delete any other; finally, the filtered signals are analyzed with both, the Kuramoto’s order parameter to quantify the dynamic synchronization of the gearbox and the phase diagram to characterize its stability. The results demonstrates the utility of the second DOF in the design of the planetary gearbox in order to avoid excessive torques in the components of the system. Furthermore, it is found that the synchronization of the system increases at higher operating speed, however, the system becomes unstable as the operating speed is increased.
{"title":"Dynamic Characterization of a Two Degree of Freedom Planetary Gearbox During Varying Load Conditions","authors":"C. A. González-Cruz, J. Jauregui, M. Ceccarelli","doi":"10.1115/gt2019-91862","DOIUrl":"https://doi.org/10.1115/gt2019-91862","url":null,"abstract":"\u0000 This paper presents the dynamic characterization of a two degree of freedom planetary gearbox prototype during the variation of the load condition. Tests with varying load are developed at three different operating speeds of the input shaft: 190, 380 and 590 rpm. The dynamic torques and vibrations on the input and output shafts are acquired during the experiments, such as the angular velocity of the output shaft. The experimental data are analyzed to evaluate the dynamics of the system during the exchange of operation between the first and second DOF operation. Then, the radial vibrations are analyzed during the operation of the second DOF by means of a methodology using different signal processing tools: first, the continuous wavelet transform is used to identify the nonlinear behavior and the main frequency content of the system; then, the vibrations are filtered by means of passband filters in order to keep the main frequencies of the system and delete any other; finally, the filtered signals are analyzed with both, the Kuramoto’s order parameter to quantify the dynamic synchronization of the gearbox and the phase diagram to characterize its stability. The results demonstrates the utility of the second DOF in the design of the planetary gearbox in order to avoid excessive torques in the components of the system. Furthermore, it is found that the synchronization of the system increases at higher operating speed, however, the system becomes unstable as the operating speed is increased.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"159 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126741167","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In many supercritical CO2 cycle implementations, compressor or pump inlet conditions are relatively near the two-phase region. Fluid acceleration near the compressor inlet can result in the potential for condensation or cavitation at the inlet. Despite potential mitigating effects or evidence in the literature, potential two-phase operation is a high-risk condition and may not be recommended for high-reliability system design. This paper presents a summary of the existing literature documenting inlet phase change in sCO2, and presents an analysis of required conditions to avoid phase change as a function of inlet pressure, temperature, and Mach number. Static conditions at the inlet are calculated based on the real gas approach documented in ASME PTC-10, Appendix G. In addition, various total-to-static iteration challenges are discussed and avoided through solution of the inverse problem to convert limiting static conditions at saturation to the full range of limiting total conditions for various Mach numbers up to 1.0. The results show that a threshold total temperature exists above which phase change cannot occur, ranging from 31.1 to 66.95 °C and increasing with Mach number. Lower temperatures below this threshold may also avoid phase change depending on the total pressure. The documented results are useful as a reference for use by cycle designers to impose design limits that minimize risks associated with two-phase flow in the compressor.
{"title":"Limiting Inlet Conditions for Phase Change Avoidance in Supercritical CO2 Compressors","authors":"T. Allison, Aaron Mcclung","doi":"10.1115/gt2019-90409","DOIUrl":"https://doi.org/10.1115/gt2019-90409","url":null,"abstract":"\u0000 In many supercritical CO2 cycle implementations, compressor or pump inlet conditions are relatively near the two-phase region. Fluid acceleration near the compressor inlet can result in the potential for condensation or cavitation at the inlet. Despite potential mitigating effects or evidence in the literature, potential two-phase operation is a high-risk condition and may not be recommended for high-reliability system design. This paper presents a summary of the existing literature documenting inlet phase change in sCO2, and presents an analysis of required conditions to avoid phase change as a function of inlet pressure, temperature, and Mach number. Static conditions at the inlet are calculated based on the real gas approach documented in ASME PTC-10, Appendix G. In addition, various total-to-static iteration challenges are discussed and avoided through solution of the inverse problem to convert limiting static conditions at saturation to the full range of limiting total conditions for various Mach numbers up to 1.0. The results show that a threshold total temperature exists above which phase change cannot occur, ranging from 31.1 to 66.95 °C and increasing with Mach number. Lower temperatures below this threshold may also avoid phase change depending on the total pressure. The documented results are useful as a reference for use by cycle designers to impose design limits that minimize risks associated with two-phase flow in the compressor.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131348826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An adaptive Gaussian quadrature method for characterizing flow over three dimensional bodies via a boundary element method using isoparametric quadrilateral elements with non-constant source and dipole strengths has been developed and tested. This method is compared to state-of-the-art methods: flat elements with constant strengths, flat elements with bilinear strengths, and twisted elements with constant dipole strengths. As such, an overview of current boundary element methods is provided. The method developed here for twisted elements with non-constant source and dipole strengths is advantageous in that it both better approximates the actual geometry of the surface and the distribution of the dipole and source strengths. The majority of current methods are lacking at least one of these attributes. The developed method has been validated by comparison to two known analytical solutions: a non-lifting ellipsoid and a Kármán-Trefftz airfoil. The flexible and robust procedure presented here results in improved accuracy of the solution to the Laplace equation around three dimensional bodies.
{"title":"Implementation of Adaptive Gaussian Quadrature for Improved Accuracy of Boundary Element Methods Applied to Three Dimensional Geometries","authors":"Michael Davies, Joseph Saverin","doi":"10.1115/gt2019-91499","DOIUrl":"https://doi.org/10.1115/gt2019-91499","url":null,"abstract":"\u0000 An adaptive Gaussian quadrature method for characterizing flow over three dimensional bodies via a boundary element method using isoparametric quadrilateral elements with non-constant source and dipole strengths has been developed and tested. This method is compared to state-of-the-art methods: flat elements with constant strengths, flat elements with bilinear strengths, and twisted elements with constant dipole strengths. As such, an overview of current boundary element methods is provided.\u0000 The method developed here for twisted elements with non-constant source and dipole strengths is advantageous in that it both better approximates the actual geometry of the surface and the distribution of the dipole and source strengths. The majority of current methods are lacking at least one of these attributes.\u0000 The developed method has been validated by comparison to two known analytical solutions: a non-lifting ellipsoid and a Kármán-Trefftz airfoil. The flexible and robust procedure presented here results in improved accuracy of the solution to the Laplace equation around three dimensional bodies.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132929027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A gas turbine is usually installed inside a package to reduce the acoustics emissions and protect against adverse environmental conditions. An enclosure ventilation system is keeps temperatures under acceptable limits and dilutes any potentially explosive accumulation of gas due to unexpected leakages. The functional and structural integrity as well as certification needs of the instrumentation and auxiliary systems in the package require that temperatures do not exceed a given threshold. Moreover, accidental fuel gas leakages inside the package must be studied in detail for safety purposes as required by ISO21789. CFD is routinely used in BHGE (Baker Hughes, a GE Company) to assist in the design and verification of the complete enclosure and ventilation system. This may require multiple CFD runs of very complex domains and flow fields in several operating conditions, with a large computational effort. Modeling assumptions and simulation set-up in terms of turbulence and thermal models, and the steady or unsteady nature of the simulations must be carefully assessed. In order to find a good compromise between accuracy and computational effort the present work focuses on the analysis of three different approaches, RANS, URANS and Hybrid-LES. The different computational approaches are first applied to an isothermal scaled-down model for validation purposes where it was possible to determine the impact of the large-scale flow unsteadiness and compare with measurements. Then, the analysis proceeds to a full-scale real aero-derivative gas turbine package. in which the aero and thermal field were investigated by a set of URANS and Hybrid-LES that includes the heat released by the engine. The different approaches are compared by analyzing flow and temperature fields. Finally, an accidental gas leak and the subsequent gas diffusion and/or accumulation inside the package are studied and compared. The outcome of this work highlights how the most suitable approach to be followed for industrial purposes depends on the goal of the CFD study and on the specific scenario, such as NPI Program or RQS Project.
{"title":"The Impact of Model Assumptions on the CFD Assisted Design of Gas Turbine Packages","authors":"G. Lucherini, V. Michelassi, S. Minotti","doi":"10.1115/gt2019-90871","DOIUrl":"https://doi.org/10.1115/gt2019-90871","url":null,"abstract":"\u0000 A gas turbine is usually installed inside a package to reduce the acoustics emissions and protect against adverse environmental conditions. An enclosure ventilation system is keeps temperatures under acceptable limits and dilutes any potentially explosive accumulation of gas due to unexpected leakages. The functional and structural integrity as well as certification needs of the instrumentation and auxiliary systems in the package require that temperatures do not exceed a given threshold. Moreover, accidental fuel gas leakages inside the package must be studied in detail for safety purposes as required by ISO21789. CFD is routinely used in BHGE (Baker Hughes, a GE Company) to assist in the design and verification of the complete enclosure and ventilation system. This may require multiple CFD runs of very complex domains and flow fields in several operating conditions, with a large computational effort. Modeling assumptions and simulation set-up in terms of turbulence and thermal models, and the steady or unsteady nature of the simulations must be carefully assessed. In order to find a good compromise between accuracy and computational effort the present work focuses on the analysis of three different approaches, RANS, URANS and Hybrid-LES. The different computational approaches are first applied to an isothermal scaled-down model for validation purposes where it was possible to determine the impact of the large-scale flow unsteadiness and compare with measurements. Then, the analysis proceeds to a full-scale real aero-derivative gas turbine package. in which the aero and thermal field were investigated by a set of URANS and Hybrid-LES that includes the heat released by the engine. The different approaches are compared by analyzing flow and temperature fields. Finally, an accidental gas leak and the subsequent gas diffusion and/or accumulation inside the package are studied and compared. The outcome of this work highlights how the most suitable approach to be followed for industrial purposes depends on the goal of the CFD study and on the specific scenario, such as NPI Program or RQS Project.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130771014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Outboard-traverse flame migration in an annular profile, combustion gas pathway of a Siemens aero-derivative turbine engine can be detected with a dual immersion thermocouple. This solution is applicable for Oil & Gas operators using gas turbines fueled by natural gas. The typical flame profile within the annular combustion gas flow path is disturbed by introducing poor quality fuel into the engine. The skewed or outward bias flame profile in turn causes severe overheating of the hot section components around the outer radius of the annular combustor exit wall covering a number of hot section components. This ultimately causes accelerated components deterioration and failure to meet its target design life. Consequently, resulting in rejection of these components and increasing the life cycle cost of their asset operations. The introduction of the dual immersion thermocouple allow us to detect outward bias flame pattern using the exhaust gas temperature profile during operation and warn the operator of this condition via software alarm and trip provision. By implementing a means of detecting outward bias flame patterns, the operator will be made aware of this condition and can then take means to resolve this matter by first, allowing to optimize hot section components boundary limits and saving overhaul costs and second, avoid unplanned maintenance outages due to hot section premature failures.
{"title":"A Methodology and Case Study of Outboard Traverse Flame Detection on Aeroderivative Gas Turbines","authors":"J. Jacques, Noor Azman Mohamat Nor","doi":"10.1115/gt2019-90158","DOIUrl":"https://doi.org/10.1115/gt2019-90158","url":null,"abstract":"\u0000 Outboard-traverse flame migration in an annular profile, combustion gas pathway of a Siemens aero-derivative turbine engine can be detected with a dual immersion thermocouple. This solution is applicable for Oil & Gas operators using gas turbines fueled by natural gas. The typical flame profile within the annular combustion gas flow path is disturbed by introducing poor quality fuel into the engine. The skewed or outward bias flame profile in turn causes severe overheating of the hot section components around the outer radius of the annular combustor exit wall covering a number of hot section components. This ultimately causes accelerated components deterioration and failure to meet its target design life. Consequently, resulting in rejection of these components and increasing the life cycle cost of their asset operations. The introduction of the dual immersion thermocouple allow us to detect outward bias flame pattern using the exhaust gas temperature profile during operation and warn the operator of this condition via software alarm and trip provision. By implementing a means of detecting outward bias flame patterns, the operator will be made aware of this condition and can then take means to resolve this matter by first, allowing to optimize hot section components boundary limits and saving overhaul costs and second, avoid unplanned maintenance outages due to hot section premature failures.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121938026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Inderpal Sihra, Ian Goldswain, Christina P. Twist, Jorge E. Pacheco
Methane emissions are classed as one of the most important contributors to climate change. This greenhouse gas has a global warming potential 21 times that of Carbon Dioxide. In the Oil and Gas industry, pipeline compressor emissions have been identified as an important source of methane released into the atmosphere. Wet seals (oil seals) technology will not meet new targets being set for methane emissions. John Crane has therefore developed a new dry gas seal design with a significantly narrower cross section to allow historically high value compressor assets to continue to function without the need for extensive redesign or replacement. This dry gas seal has been specifically engineered to replace wet seals within older centrifugal pipeline compressors. The main reasons associated with conversion from wet seals to dry gas seals include: moving to non-contacting technology which reduces seal wear issues, reduced operating costs from removal of oil seal supporting systems including degassing equipment, lower energy consumption due to the shear losses associated with oil seals, reduced maintenance costs by having a simpler supporting system and less frequent routine maintenance, and reduced emissions. Wet seals are typically compact in nature and are therefore very flexible in how they can be installed into a compressor. Traditional dry gas seals occupy a larger cross-sectional footprint and therefore it was necessary to develop a brand new gas seal that can retrofit into the same cavity without the need for expensive and prohibitive machining of the compressor shaft or housing. The resulting gas seal design is significantly compact when compared to a standard gas seal, yet provides sealing at maximum pipeline compressor duties of up to 120barg and 100m/s. In order to create a compact seal, John Crane has significantly reduced the cross section of the rotating (mating) and stationary (primary) sealing faces. This change brings about an increased level of complexity associated with dry gas seal design. In-house FEA and CFD simulations have been used to optimize the seal design and groove patterns. Results documenting the extensive design and simulation activities will be presented to demonstrate effective separation of the sealing faces throughout the entire seal performance envelope. A number of tests were specifically designed to thoroughly validate the seal design by simulating compressor field conditions. The product has undergone a series of testing through its entire performance envelope for pressure, speed and temperature. Specific accelerated tests were also designed to replicate the seal lifetime. The paper will describe the test setup and present the validation results.
{"title":"Pipeline Compressors Dry Gas Seal Retrofits","authors":"Inderpal Sihra, Ian Goldswain, Christina P. Twist, Jorge E. Pacheco","doi":"10.1115/gt2019-91865","DOIUrl":"https://doi.org/10.1115/gt2019-91865","url":null,"abstract":"\u0000 Methane emissions are classed as one of the most important contributors to climate change. This greenhouse gas has a global warming potential 21 times that of Carbon Dioxide. In the Oil and Gas industry, pipeline compressor emissions have been identified as an important source of methane released into the atmosphere. Wet seals (oil seals) technology will not meet new targets being set for methane emissions. John Crane has therefore developed a new dry gas seal design with a significantly narrower cross section to allow historically high value compressor assets to continue to function without the need for extensive redesign or replacement.\u0000 This dry gas seal has been specifically engineered to replace wet seals within older centrifugal pipeline compressors. The main reasons associated with conversion from wet seals to dry gas seals include: moving to non-contacting technology which reduces seal wear issues, reduced operating costs from removal of oil seal supporting systems including degassing equipment, lower energy consumption due to the shear losses associated with oil seals, reduced maintenance costs by having a simpler supporting system and less frequent routine maintenance, and reduced emissions.\u0000 Wet seals are typically compact in nature and are therefore very flexible in how they can be installed into a compressor. Traditional dry gas seals occupy a larger cross-sectional footprint and therefore it was necessary to develop a brand new gas seal that can retrofit into the same cavity without the need for expensive and prohibitive machining of the compressor shaft or housing. The resulting gas seal design is significantly compact when compared to a standard gas seal, yet provides sealing at maximum pipeline compressor duties of up to 120barg and 100m/s.\u0000 In order to create a compact seal, John Crane has significantly reduced the cross section of the rotating (mating) and stationary (primary) sealing faces. This change brings about an increased level of complexity associated with dry gas seal design. In-house FEA and CFD simulations have been used to optimize the seal design and groove patterns. Results documenting the extensive design and simulation activities will be presented to demonstrate effective separation of the sealing faces throughout the entire seal performance envelope. A number of tests were specifically designed to thoroughly validate the seal design by simulating compressor field conditions. The product has undergone a series of testing through its entire performance envelope for pressure, speed and temperature. Specific accelerated tests were also designed to replicate the seal lifetime. The paper will describe the test setup and present the validation results.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"409 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123539044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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