To ensure safe and reliable operation, steam turbine casings must have acceptable stresses and maintain sealing when subjected to internal pressures and temperatures. To show turbine casings acceptable, analysts conduct structural evaluations using finite element analysis (FEA) techniques. This paper outlines the analytical methods used to perform these types of analyses, provides analysis examples, and summarizes the process to create pressure and temperature limit maps. Finite element models of the main casing and steam chest are used to determine stresses and sealing of the casing horizontal split line and steam chest cover during normal operation. The sealing evaluations consider the sealing capabilities of the bolted joints when the casing is subjected to internal steam pressure and consider the effects of bolt stress relaxation at elevated temperatures, joint contact surface separation, and penetration of the internal pressure into the sealing surface. The acceptance criteria for the bolted joint sealing is based on the minimum width of the contacting surface and the minimum joint contact pressure. A series of analyses were conducted on the various models to create pressure and temperature limit maps, so that the design can be applied for the appropriate conditions. These maps plot maximum allowable working pressure (MAWP) versus maximum allowable working temperature (MAWT), and allow an application engineer to easily determine the acceptability of the casing for a particular application. An explanation of the process used to create the limit maps is presented.
{"title":"Steam Turbine Casing Analyses to Determine Pressure and Temperature Limits","authors":"P. T. Smith, D. Griffin","doi":"10.1115/gt2021-59535","DOIUrl":"https://doi.org/10.1115/gt2021-59535","url":null,"abstract":"\u0000 To ensure safe and reliable operation, steam turbine casings must have acceptable stresses and maintain sealing when subjected to internal pressures and temperatures. To show turbine casings acceptable, analysts conduct structural evaluations using finite element analysis (FEA) techniques. This paper outlines the analytical methods used to perform these types of analyses, provides analysis examples, and summarizes the process to create pressure and temperature limit maps.\u0000 Finite element models of the main casing and steam chest are used to determine stresses and sealing of the casing horizontal split line and steam chest cover during normal operation. The sealing evaluations consider the sealing capabilities of the bolted joints when the casing is subjected to internal steam pressure and consider the effects of bolt stress relaxation at elevated temperatures, joint contact surface separation, and penetration of the internal pressure into the sealing surface. The acceptance criteria for the bolted joint sealing is based on the minimum width of the contacting surface and the minimum joint contact pressure.\u0000 A series of analyses were conducted on the various models to create pressure and temperature limit maps, so that the design can be applied for the appropriate conditions. These maps plot maximum allowable working pressure (MAWP) versus maximum allowable working temperature (MAWT), and allow an application engineer to easily determine the acceptability of the casing for a particular application. An explanation of the process used to create the limit maps is presented.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128103936","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}
Evaporation cooling increases gas turbine power output. Experimental results suggest an 8% increase of power when 1% of the overall mass flow is added via water droplets injected upstream of the compressor. However, water injection has an impact on the flow field, which requires experimental research involving probe measurements in the droplet-laden flow as well as reliable monitoring during operation, as the volumetric flow rate throughout the stages changes notably and deviates from (dry) design parameters. Measuring with a conventional pressure probe in two-phase flows is challenging because the droplet-laden flow can clog the pressure taps, thus effectively separating the sensor from the measurement location. This paper presents a consistent approach to measure stagnation pressure in a droplet-laden flow field. The probe was purged constantly to prevent droplets from clogging the tubing. The recorded pressure is then corrected using a transfer function to account for the purging pressure offset. A detailed description of how to obtain this function is given within the paper. With this setup, the flow field downstream of a blade cascade was measured at several water mass fractions and spray characteristics. The pressure measurements are compared with the usual LDA/PDA measurements in the wake of the cascade. Based on the test results, an evaluation of the change of total-head loss due to water injection and evaporation compared to dry operation can be performed.
{"title":"An Approach to Measure Total-Head in Wakes and Near End Walls at High Fogging Conditions","authors":"J. Harbeck, Silvio Geist, M. Schatz","doi":"10.1115/gt2021-59190","DOIUrl":"https://doi.org/10.1115/gt2021-59190","url":null,"abstract":"\u0000 Evaporation cooling increases gas turbine power output. Experimental results suggest an 8% increase of power when 1% of the overall mass flow is added via water droplets injected upstream of the compressor. However, water injection has an impact on the flow field, which requires experimental research involving probe measurements in the droplet-laden flow as well as reliable monitoring during operation, as the volumetric flow rate throughout the stages changes notably and deviates from (dry) design parameters. Measuring with a conventional pressure probe in two-phase flows is challenging because the droplet-laden flow can clog the pressure taps, thus effectively separating the sensor from the measurement location. This paper presents a consistent approach to measure stagnation pressure in a droplet-laden flow field. The probe was purged constantly to prevent droplets from clogging the tubing. The recorded pressure is then corrected using a transfer function to account for the purging pressure offset. A detailed description of how to obtain this function is given within the paper. With this setup, the flow field downstream of a blade cascade was measured at several water mass fractions and spray characteristics. The pressure measurements are compared with the usual LDA/PDA measurements in the wake of the cascade. Based on the test results, an evaluation of the change of total-head loss due to water injection and evaporation compared to dry operation can be performed.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122301069","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}
Fabrizio Piras, F. Bucciarelli, D. Checcacci, Filippo Ingrasciotta
In turbomachinery applications the possibility to reduce size and costs of main flow-path components, by increasing shaft rotating speed, has always been appealing. The technological challenge in increasing this power density capability is typically related to performance prediction, to operating stress in blades and shafts, as well as to the need for a more accurate rotor-dynamic analysis. Yet another aspect, often reduced to standard assessments in less demanding applications, is related to the analysis of overspeed scenarios where, following a sudden loss of load and/or driven inertia, the turbomachine shall maintain its mechanical integrity. Especially in steam turbines applications, where the behavior of the machine is strongly affected by the plant conditions, valves intervention time and connected volumes, the reduction of the rotor inertia, against comparable power, may produce overspeed scenarios that can become a primary design constraint and, if overlooked, may have both availability and safety implications. In this paper several approaches to the analysis of overspeed scenarios are discussed, with increasing level of detail. The energy-based overspeed analysis method, as required by API612, is first discussed against practical design cases. A more accurate dynamic model is then presented, and its results compared with those of the energy-based approach. Finally, the sensitivity analysis of the overspeed peak value with respect to critical design parameters is discussed. With respect to previous works, mostly based on load rejection scenarios, the main focus is on the scenario of sudden coupling loss.
{"title":"Steam Turbine Overspeed Scenarios: Comparison Between API Energy Method and Dynamic Simulation","authors":"Fabrizio Piras, F. Bucciarelli, D. Checcacci, Filippo Ingrasciotta","doi":"10.1115/gt2021-59257","DOIUrl":"https://doi.org/10.1115/gt2021-59257","url":null,"abstract":"\u0000 In turbomachinery applications the possibility to reduce size and costs of main flow-path components, by increasing shaft rotating speed, has always been appealing. The technological challenge in increasing this power density capability is typically related to performance prediction, to operating stress in blades and shafts, as well as to the need for a more accurate rotor-dynamic analysis. Yet another aspect, often reduced to standard assessments in less demanding applications, is related to the analysis of overspeed scenarios where, following a sudden loss of load and/or driven inertia, the turbomachine shall maintain its mechanical integrity.\u0000 Especially in steam turbines applications, where the behavior of the machine is strongly affected by the plant conditions, valves intervention time and connected volumes, the reduction of the rotor inertia, against comparable power, may produce overspeed scenarios that can become a primary design constraint and, if overlooked, may have both availability and safety implications.\u0000 In this paper several approaches to the analysis of overspeed scenarios are discussed, with increasing level of detail. The energy-based overspeed analysis method, as required by API612, is first discussed against practical design cases. A more accurate dynamic model is then presented, and its results compared with those of the energy-based approach. Finally, the sensitivity analysis of the overspeed peak value with respect to critical design parameters is discussed. With respect to previous works, mostly based on load rejection scenarios, the main focus is on the scenario of sudden coupling loss.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127633716","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}
Tommaso Diurno, S. G. Tomasello, T. Fondelli, A. Andreini, B. Facchini, L. Nettis, Lorenzo Arcangeli
Nowadays, the ever-increasing world electricity generation by renewable energy sources has brought about changes in conventional power plants, especially in those ones where large steam turbines work, which were widely used to meet the world’s energy needs by operating mostly at fixed conditions. Now, instead, they have to be capable to operate with greater flexibility, including rapid load changes and quick starts as well, in order to make the most of the renewable resources while guaranteeing the coverage of any shortcomings of the latter with traditional fossil fuel systems. Such service conditions are particularly challenging for the exhaust hoods, which have a great influence on the overall turbine performance, especially at off-design conditions. In fact, the complex and high rotational 3D flow generated within the diffuser and the exhaust hood outer casing can cause an increase in aerodynamic losses along with the detriment of the hood recovery performance. For these reasons, an optimized design and adequate prediction of the exhaust hood performance under all the machine operating conditions is mandatory. Since it has been widely proven that the exhaust hood flow strongly interacts with the turbine rear stage, the necessity to model this as well into a CFD modeling becomes crucial, requiring a remarkable computational effort, especially for full transient simulations. Even if adopting simplified approaches to model the last stage and exhaust hood interfaces, such as the so-called Frozen Rotor and the Mixing Plane ones, helps to keep the computational cost low, it can be not for an exhaust hood optimization process, which requires a significant number of CFD simulations to identify the most performing geometry configuration. For these reasons, a simplified model of the exhaust hood must be adopted to analyse all the possible design variants within a feasible time. The purpose of this work is to present a strategy for the exhaust hood design based on the definition of a simplified CFD model. A parametric model has been developed as a function of key geometrical parameters of both the exhaust hood and the diffuser, taking into account the strong fluid-dynamic coupling between these components. A periodic approximation has been introduced to model the exhaust hood domain, thus allowing to augment the number of the geometrical parameters of the DOE, while keeping the computational effort low. A response surface has been achieved as a function of the key geometrical parameters, therefore an optimization method has allowed identifying the best performing configuration. A 3D model of the optimized periodic geometry has been then generated to assess the effectiveness of the procedure here presented. Finally, the presented procedure has been applied in several off-design operating conditions, in order to find out an optimal geometry for each operating point, evaluating how much they differ from that one got for the design point.
{"title":"Development of a Design Approach for the Optimization of Steam Turbine Exhaust System Performance Through CFD Modelling","authors":"Tommaso Diurno, S. G. Tomasello, T. Fondelli, A. Andreini, B. Facchini, L. Nettis, Lorenzo Arcangeli","doi":"10.1115/gt2021-59268","DOIUrl":"https://doi.org/10.1115/gt2021-59268","url":null,"abstract":"\u0000 Nowadays, the ever-increasing world electricity generation by renewable energy sources has brought about changes in conventional power plants, especially in those ones where large steam turbines work, which were widely used to meet the world’s energy needs by operating mostly at fixed conditions. Now, instead, they have to be capable to operate with greater flexibility, including rapid load changes and quick starts as well, in order to make the most of the renewable resources while guaranteeing the coverage of any shortcomings of the latter with traditional fossil fuel systems. Such service conditions are particularly challenging for the exhaust hoods, which have a great influence on the overall turbine performance, especially at off-design conditions. In fact, the complex and high rotational 3D flow generated within the diffuser and the exhaust hood outer casing can cause an increase in aerodynamic losses along with the detriment of the hood recovery performance. For these reasons, an optimized design and adequate prediction of the exhaust hood performance under all the machine operating conditions is mandatory. Since it has been widely proven that the exhaust hood flow strongly interacts with the turbine rear stage, the necessity to model this as well into a CFD modeling becomes crucial, requiring a remarkable computational effort, especially for full transient simulations. Even if adopting simplified approaches to model the last stage and exhaust hood interfaces, such as the so-called Frozen Rotor and the Mixing Plane ones, helps to keep the computational cost low, it can be not for an exhaust hood optimization process, which requires a significant number of CFD simulations to identify the most performing geometry configuration. For these reasons, a simplified model of the exhaust hood must be adopted to analyse all the possible design variants within a feasible time.\u0000 The purpose of this work is to present a strategy for the exhaust hood design based on the definition of a simplified CFD model. A parametric model has been developed as a function of key geometrical parameters of both the exhaust hood and the diffuser, taking into account the strong fluid-dynamic coupling between these components. A periodic approximation has been introduced to model the exhaust hood domain, thus allowing to augment the number of the geometrical parameters of the DOE, while keeping the computational effort low. A response surface has been achieved as a function of the key geometrical parameters, therefore an optimization method has allowed identifying the best performing configuration. A 3D model of the optimized periodic geometry has been then generated to assess the effectiveness of the procedure here presented. Finally, the presented procedure has been applied in several off-design operating conditions, in order to find out an optimal geometry for each operating point, evaluating how much they differ from that one got for the design point.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130039249","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}
T. Allison, John D. Klaerner, Stefan D. Cich, R. Kurz, Marybeth McBain
The introduction of hydrogen or synthetic natural gas produced from renewable electricity into gas pipelines is being considered to enable decarbonization and energy storage. Prior published studies show that hydrogen concentrations over 20–30% are likely to require significant infrastructure modifications and that significant concentrations of hydrogen will decrease energy transport capacity and/or reduce transport efficiency due to higher compression work. A comparative analysis of four power-to-gas implementations utilizing alkaline electrolysis, steam methane reforming, and catalytic methanation at hydrogen concentrations from 0–100% is performed in order to quantify production and transport power requirements utilizing pipeline or electrical transport. The pipeline transport analysis evaluates the pipeline transport capacity, efficiency, and emissions at various hydrogen concentrations and their sensitivity to pipeline diameter and compressor station spacing. The results show that production costs for hydrogen and synthetic natural gas dominate the overall energy requirement, requiring more power to create product than will be delivered for end use. Pipeline transport power requirements also increase by a maximum factor of 6–8 depending on surface roughness at high hydrogen percentages, but pipeline transport losses are less than electrical transmission losses in all cases. The increased pipeline compression power increases CO2 emissions along the pipeline up to a peak value of 240% relative to pure methane at a mole fraction of 65% hydrogen, above which CO2 emissions reduce. An analysis of pipeline compression conditions shows that flow requirements for all cases exceed the capabilities of reciprocating compressors but are mostly within the capabilities of centrifugal compressors, although multiple bodies may be required at hydrogen concentrations exceeding approximately 40–85%.
{"title":"Power and Compression Analysis of Power-To-Gas Implementations in Natural Gas Pipelines With Up to 100% Hydrogen Concentration","authors":"T. Allison, John D. Klaerner, Stefan D. Cich, R. Kurz, Marybeth McBain","doi":"10.1115/gt2021-59398","DOIUrl":"https://doi.org/10.1115/gt2021-59398","url":null,"abstract":"\u0000 The introduction of hydrogen or synthetic natural gas produced from renewable electricity into gas pipelines is being considered to enable decarbonization and energy storage. Prior published studies show that hydrogen concentrations over 20–30% are likely to require significant infrastructure modifications and that significant concentrations of hydrogen will decrease energy transport capacity and/or reduce transport efficiency due to higher compression work. A comparative analysis of four power-to-gas implementations utilizing alkaline electrolysis, steam methane reforming, and catalytic methanation at hydrogen concentrations from 0–100% is performed in order to quantify production and transport power requirements utilizing pipeline or electrical transport. The pipeline transport analysis evaluates the pipeline transport capacity, efficiency, and emissions at various hydrogen concentrations and their sensitivity to pipeline diameter and compressor station spacing. The results show that production costs for hydrogen and synthetic natural gas dominate the overall energy requirement, requiring more power to create product than will be delivered for end use. Pipeline transport power requirements also increase by a maximum factor of 6–8 depending on surface roughness at high hydrogen percentages, but pipeline transport losses are less than electrical transmission losses in all cases. The increased pipeline compression power increases CO2 emissions along the pipeline up to a peak value of 240% relative to pure methane at a mole fraction of 65% hydrogen, above which CO2 emissions reduce. An analysis of pipeline compression conditions shows that flow requirements for all cases exceed the capabilities of reciprocating compressors but are mostly within the capabilities of centrifugal compressors, although multiple bodies may be required at hydrogen concentrations exceeding approximately 40–85%.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130961467","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}
Rasish Khatri, Jeremy Liu, Freddie Sarhan, O. Najeeb, H. Kajita, M. Kozuka
This paper describes the design and development of an innovative 280 kW and a 125 kW Turboexpander Generator (TEG) for natural gas pressure letdown (PLD) applications. The flange-to-flange TEG is supported by active magnetic bearings (AMB) and uses an advanced thrust balancing scheme to minimize the net load on the thrust bearing. The machine designs for the two TEG frame sizes are very similar to maintain commonality between parts. A review of the high-speed generator (HSG) and AMB design is provided. A complete AMB closed-loop dynamics study is presented, including a comprehensive rotordynamics and controls analysis. The touchdown bearing design is shown and discussed, and design details of the touchdown bearing resilient mount are presented. The touchdown bearings are given resilience with a tolerance ring. A detailed simulation of a rotor touchdown event at full speed is shown. The magnetic bearing controller (MBC) and variable speed drive (VSD) are located approximately 35 m from the TEG, exposed to the outside environment, and are not required to be explosion-proof. The prototype TEGs are intended to be manufactured and tested in Q1 2021. They will be commissioned, and field tested in Q2 2021. A follow-up paper detailing the mechanical testing and field testing of the units will follow in 2022.
{"title":"The Development of Turboexpander-Generators for Gas Pressure Letdown Part I: Design and Analysis","authors":"Rasish Khatri, Jeremy Liu, Freddie Sarhan, O. Najeeb, H. Kajita, M. Kozuka","doi":"10.1115/gt2021-60125","DOIUrl":"https://doi.org/10.1115/gt2021-60125","url":null,"abstract":"\u0000 This paper describes the design and development of an innovative 280 kW and a 125 kW Turboexpander Generator (TEG) for natural gas pressure letdown (PLD) applications. The flange-to-flange TEG is supported by active magnetic bearings (AMB) and uses an advanced thrust balancing scheme to minimize the net load on the thrust bearing. The machine designs for the two TEG frame sizes are very similar to maintain commonality between parts. A review of the high-speed generator (HSG) and AMB design is provided. A complete AMB closed-loop dynamics study is presented, including a comprehensive rotordynamics and controls analysis. The touchdown bearing design is shown and discussed, and design details of the touchdown bearing resilient mount are presented. The touchdown bearings are given resilience with a tolerance ring. A detailed simulation of a rotor touchdown event at full speed is shown. The magnetic bearing controller (MBC) and variable speed drive (VSD) are located approximately 35 m from the TEG, exposed to the outside environment, and are not required to be explosion-proof. The prototype TEGs are intended to be manufactured and tested in Q1 2021. They will be commissioned, and field tested in Q2 2021. A follow-up paper detailing the mechanical testing and field testing of the units will follow in 2022.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133606252","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}
Since it is difficult to directly measure the transient stress of a steam turbine rotor in operation, a rotor stress field reconstruction model based on deep fully convolutional network for the start-up process is proposed. The stress distribution in the rotor can be directly predicted based on the temperature of a few measurement points. First, the finite element model is used to accurately simulate the temperature and stress field of the rotor start-up process, generating training data for the deep learning method. Next, data of only 15 temperature measurement points are arranged to predict the stress distribution in critical area of the rotor surface, with the accuracy (R2-score) reaching 0.997. The time cost of the trained neural network model at a single case is 1.42s in CPUs and 0.11s in GPUs, shortened by 97.3% and 99.8% with comparison to finite element analysis, respectively. In addition, the influence of the number of temperature measurement points and the training size are discussed, verifying the stability of the model. With the advantages of fast calculation, high accuracy and strong stability, the fast reconstruction model can effectively realize the stress prediction during start-up processes, resulting in the possibility of real-time diagnosis of rotor strength in operation.
{"title":"Fast Reconstruction Method of the Stress Field for the Steam Turbine Rotor Based on Deep Fully Convolutional Network","authors":"Guo Ding, Tianyuan Liu, Di Zhang, Yonghui Xie","doi":"10.1115/gt2021-60355","DOIUrl":"https://doi.org/10.1115/gt2021-60355","url":null,"abstract":"\u0000 Since it is difficult to directly measure the transient stress of a steam turbine rotor in operation, a rotor stress field reconstruction model based on deep fully convolutional network for the start-up process is proposed. The stress distribution in the rotor can be directly predicted based on the temperature of a few measurement points. First, the finite element model is used to accurately simulate the temperature and stress field of the rotor start-up process, generating training data for the deep learning method. Next, data of only 15 temperature measurement points are arranged to predict the stress distribution in critical area of the rotor surface, with the accuracy (R2-score) reaching 0.997. The time cost of the trained neural network model at a single case is 1.42s in CPUs and 0.11s in GPUs, shortened by 97.3% and 99.8% with comparison to finite element analysis, respectively. In addition, the influence of the number of temperature measurement points and the training size are discussed, verifying the stability of the model. With the advantages of fast calculation, high accuracy and strong stability, the fast reconstruction model can effectively realize the stress prediction during start-up processes, resulting in the possibility of real-time diagnosis of rotor strength in operation.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121706294","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}
Gas-liquid scrubbers rely on level control systems (generally consisting of a level indicator, a level controller, and a pneumatic control valve for liquid release) to maintain an appropriate liquid level within the vessel. Scrubbers are often upstream of turbomachinery and failures at the scrubber can cause liquid ingestion or downtime. In natural gas service, these control systems are subject to harsh environments due to the influx of liquid slugs, high-velocity gases, corrosive fluids, vibrations, and a chaotic gas-liquid interface. In these severe conditions, level control system failures are commonplace and lead to safety and environmental hazards, equipment damage, and lost production. A need exists to augment or replace the typical liquid level control system with an alternative solution that is cost-effective, robust, and can operate reliably in the harsh natural gas environment. A project investigated failures related to scrubber level control systems, identified improvements to these systems, developed a prototype level controller, and tested the prototype controller and a variety of commercially available controllers at various conditions that emulated certain field conditions. The results of these tests gave insight into what type of controller may be best suited to the tested conditions and what controller options should be pursued further.
{"title":"Development of a Robust Scrubber Level Controller","authors":"C. Day, Griffin C. Beck, Scott A. Schubring","doi":"10.1115/gt2021-59078","DOIUrl":"https://doi.org/10.1115/gt2021-59078","url":null,"abstract":"\u0000 Gas-liquid scrubbers rely on level control systems (generally consisting of a level indicator, a level controller, and a pneumatic control valve for liquid release) to maintain an appropriate liquid level within the vessel. Scrubbers are often upstream of turbomachinery and failures at the scrubber can cause liquid ingestion or downtime. In natural gas service, these control systems are subject to harsh environments due to the influx of liquid slugs, high-velocity gases, corrosive fluids, vibrations, and a chaotic gas-liquid interface. In these severe conditions, level control system failures are commonplace and lead to safety and environmental hazards, equipment damage, and lost production. A need exists to augment or replace the typical liquid level control system with an alternative solution that is cost-effective, robust, and can operate reliably in the harsh natural gas environment. A project investigated failures related to scrubber level control systems, identified improvements to these systems, developed a prototype level controller, and tested the prototype controller and a variety of commercially available controllers at various conditions that emulated certain field conditions. The results of these tests gave insight into what type of controller may be best suited to the tested conditions and what controller options should be pursued further.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"434 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116184881","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}
R. Hombo, K. Murata, Waki Yuichiro, N. Nagata, Iwasaki Makoto, Kazuyuki Matsumoto
Accurate evaluation of the rotor stability is important for increasing the performance of the Steam Turbines. This paper discusses the important factors (such as destabilization force, bearing coefficient) for the evaluation of rotor stability. The destabilization force which varies with the type of seal suggests that seal shape plays an important role. In the past, several researchers have studied the fluid destabilization force both numerically and experimentally and prediction of the same can be done fairly accurately by applying CFD techniques. The characteristics of the fluid destabilization force can be accurately evaluated by investigating the sensitivity of parameters such as clearance and swirl velocity for each seal type using CFD. In the case of partial admission operation in which the bearing load changes (such as control stage of steam turbines), the frequency ratio effect on bearing coefficients is higher in the case of light-load (Sommerfeld number is large) than in the case of high-load (Sommerfeld number is small). In order to estimate the frequency ratio effects due to varying load accurately, an experimental study and analytical study were carried out. As a result of comparison of the test results to analytical results, the test results are in good agreement with thermo-elastic-hydrodynamic-lubrication (TEHL) analysis which considers deformation of pad obtained by 3D-FEM. The evaluation of rotor stability at each bearing load by partial admission (example: Governing Valve test) is in agreement with the field data of steam turbine. For new designs and modification designs, this assessment considering the characteristics of each parameter is effective for improving the quality of rotor design.
{"title":"Assessment of Rotor Stability for Steam Turbine Considering Labyrinth Seal Characteristics of Fluid Destabilization Force and Vibrational Frequency Effect of Bearing Coefficients","authors":"R. Hombo, K. Murata, Waki Yuichiro, N. Nagata, Iwasaki Makoto, Kazuyuki Matsumoto","doi":"10.1115/gt2021-01893","DOIUrl":"https://doi.org/10.1115/gt2021-01893","url":null,"abstract":"\u0000 Accurate evaluation of the rotor stability is important for increasing the performance of the Steam Turbines. This paper discusses the important factors (such as destabilization force, bearing coefficient) for the evaluation of rotor stability.\u0000 The destabilization force which varies with the type of seal suggests that seal shape plays an important role. In the past, several researchers have studied the fluid destabilization force both numerically and experimentally and prediction of the same can be done fairly accurately by applying CFD techniques. The characteristics of the fluid destabilization force can be accurately evaluated by investigating the sensitivity of parameters such as clearance and swirl velocity for each seal type using CFD.\u0000 In the case of partial admission operation in which the bearing load changes (such as control stage of steam turbines), the frequency ratio effect on bearing coefficients is higher in the case of light-load (Sommerfeld number is large) than in the case of high-load (Sommerfeld number is small).\u0000 In order to estimate the frequency ratio effects due to varying load accurately, an experimental study and analytical study were carried out. As a result of comparison of the test results to analytical results, the test results are in good agreement with thermo-elastic-hydrodynamic-lubrication (TEHL) analysis which considers deformation of pad obtained by 3D-FEM.\u0000 The evaluation of rotor stability at each bearing load by partial admission (example: Governing Valve test) is in agreement with the field data of steam turbine.\u0000 For new designs and modification designs, this assessment considering the characteristics of each parameter is effective for improving the quality of rotor design.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"52 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130373466","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}
Alessandro Vulpio, A. Suman, N. Casari, M. Pinelli, C. Appleby, Simon Kyte
Suspended micrometric particles are always present in the air swallowed by gas turbines. These solid particles can overpass the filters of heavy-duty gas turbines and deposit onto the internal surfaces of the compressor, leading to the overtime reduction of the machine performances, and, as a result, to the fuel consumption augmentation. A widely employed method to slow down the engine degradation is to wash the engine frequently. Over the years, the washing techniques have been continuously improved in order to reach the best compromise between low fluid consumption and high washing capabilities. In this work, an experimental campaign has been carried out to estimate the washing effectiveness on a multistage axial-flow compressor fouled with micrometric soot particles. The cleaning fluids tested in the present work were demineralized water and two cleaners provided by ZOK International Group ltd: a commercial cleaner available on the market (ZOK 27), and a new, under development, environmentally-sensitive formula. The fluids have been tested employing three droplet size distributions (with mean diameters of 20 μm, 50 μm, and 100 μm). The washing effectiveness has been assessed through image post-processing techniques by analyzing the pictures of the stator vanes and rotor blades taken in fouled and washed conditions. From the present investigation, two results arise. The finest droplets show a greater capability to remove soot deposits showing how, when the washing operation takes place during quasi-idle operating condition, the turbulent-driven motion spread smaller particles on a wider blade region. The second results is the demonstration how a environmentally-sensitive chemical formula allows the obtainment of good results in terms removal capability for the same amount of product. This finding could help the plant manager to operate the gas turbine with less constraints in terms of cost and rules.
{"title":"Washing Effectiveness Assessment of Different Cleaners on a Small-Scale Multistage Compressor","authors":"Alessandro Vulpio, A. Suman, N. Casari, M. Pinelli, C. Appleby, Simon Kyte","doi":"10.1115/gt2021-59455","DOIUrl":"https://doi.org/10.1115/gt2021-59455","url":null,"abstract":"\u0000 Suspended micrometric particles are always present in the air swallowed by gas turbines. These solid particles can overpass the filters of heavy-duty gas turbines and deposit onto the internal surfaces of the compressor, leading to the overtime reduction of the machine performances, and, as a result, to the fuel consumption augmentation. A widely employed method to slow down the engine degradation is to wash the engine frequently. Over the years, the washing techniques have been continuously improved in order to reach the best compromise between low fluid consumption and high washing capabilities. In this work, an experimental campaign has been carried out to estimate the washing effectiveness on a multistage axial-flow compressor fouled with micrometric soot particles. The cleaning fluids tested in the present work were demineralized water and two cleaners provided by ZOK International Group ltd: a commercial cleaner available on the market (ZOK 27), and a new, under development, environmentally-sensitive formula. The fluids have been tested employing three droplet size distributions (with mean diameters of 20 μm, 50 μm, and 100 μm). The washing effectiveness has been assessed through image post-processing techniques by analyzing the pictures of the stator vanes and rotor blades taken in fouled and washed conditions. From the present investigation, two results arise. The finest droplets show a greater capability to remove soot deposits showing how, when the washing operation takes place during quasi-idle operating condition, the turbulent-driven motion spread smaller particles on a wider blade region. The second results is the demonstration how a environmentally-sensitive chemical formula allows the obtainment of good results in terms removal capability for the same amount of product. This finding could help the plant manager to operate the gas turbine with less constraints in terms of cost and rules.","PeriodicalId":252904,"journal":{"name":"Volume 8: Oil and Gas Applications; Steam Turbine","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133996231","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：