Ameen Malkawi, Ahmed Aladawy, Rajesh Kumar Venkata Gadamsetty, Rafael Adolfo Lastra Melo
Downhole gas compression technology is an artificial lift method that aims to boost production, maximize recovery and delay onset of liquid loading in gas wells. There are different available compression technologies that can be considered for downhole applications, such as screw, scroll, centrifugal and axial compressors. Selection of the appropriate type mainly depends on expected well performance, ambient conditions, compressor operating envelope, technology characteristics, limitations and size constraints. The objective of this study is to perform a feasibility evaluation of compression solutions applicable for a given set of candidate gas wells. Aerodynamic and hydraulic models are used to determine operating conditions, compressor performance, and to select equipment specifications such as impeller diameter, compressor envelope, shaft HP requirement and number of stages among other parameters. A Pugh analysis is performed for all compression technologies and their characteristics to down-select the most suitable solutions for the given set of wells. The results of the analysis indicated an optimal downhole compression technology that covers most of the gas flow rate requirements and meet the performance expectations. The study also provided critical specifications for the compressor, including high-speed operation needed to provide the required flow rates and compression ratio for a relatively small housing diameter. The study also finds that other technologies may be applicable but only to certain population of wells, as the flow rate spectrum is narrower than the optimal solution at the studied conditions. The analysis for the discarded compression technologies in this study showed relatively significant disadvantages for downhole application when compared to the selected compressor. This study presents a holistic analysis for compression technology selection for gas wells that, as per to the understanding of the authors, is unique in the existing literature of gas well applications.
{"title":"Compression Technology Selection for Downhole Application in Gas Wells","authors":"Ameen Malkawi, Ahmed Aladawy, Rajesh Kumar Venkata Gadamsetty, Rafael Adolfo Lastra Melo","doi":"10.1115/gt2019-90854","DOIUrl":"https://doi.org/10.1115/gt2019-90854","url":null,"abstract":"\u0000 Downhole gas compression technology is an artificial lift method that aims to boost production, maximize recovery and delay onset of liquid loading in gas wells. There are different available compression technologies that can be considered for downhole applications, such as screw, scroll, centrifugal and axial compressors. Selection of the appropriate type mainly depends on expected well performance, ambient conditions, compressor operating envelope, technology characteristics, limitations and size constraints. The objective of this study is to perform a feasibility evaluation of compression solutions applicable for a given set of candidate gas wells.\u0000 Aerodynamic and hydraulic models are used to determine operating conditions, compressor performance, and to select equipment specifications such as impeller diameter, compressor envelope, shaft HP requirement and number of stages among other parameters. A Pugh analysis is performed for all compression technologies and their characteristics to down-select the most suitable solutions for the given set of wells.\u0000 The results of the analysis indicated an optimal downhole compression technology that covers most of the gas flow rate requirements and meet the performance expectations. The study also provided critical specifications for the compressor, including high-speed operation needed to provide the required flow rates and compression ratio for a relatively small housing diameter. The study also finds that other technologies may be applicable but only to certain population of wells, as the flow rate spectrum is narrower than the optimal solution at the studied conditions. The analysis for the discarded compression technologies in this study showed relatively significant disadvantages for downhole application when compared to the selected compressor.\u0000 This study presents a holistic analysis for compression technology selection for gas wells that, as per to the understanding of the authors, is unique in the existing literature of gas well applications.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"46 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":"132760184","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}
The last few years have witnessed researches concerned by vertical axis wind turbine (VAWT) performance considering its advantages compared to the horizontal axis wind turbines, as it can be operated in urban areas without producing noise, ease of maintenance and simple construction, in addition to its low cost. More interest is growing in developing efficient clusters of VAWT in order to increase power generation at specific sites by using multiple turbines. In the present work, the performance of various configurations of Darrieus type VAWT clusters is examined using computational fluid dynamics (CFD) simulations. The objective of this work is to increase the overall power coefficient of the turbines cluster compared to single rotor performance. This objective shall be achieved by examining mutual interactions between rotors arranged in close proximity and examining the effect of oblique angle between rotors on overall performance of the cluster of rotors. The performance is assessed by observing the overall power coefficient of the cluster. Also, the velocity wake of the simulated three rotors turbine cases was analyzed and compared to the that of the single rotor.
{"title":"CFD Investigation of the Multiple Rotors Darrieus Type Turbine Performance","authors":"O. S. Mohamed, A. Ibrahim, A. E. baz","doi":"10.1115/gt2019-91491","DOIUrl":"https://doi.org/10.1115/gt2019-91491","url":null,"abstract":"\u0000 The last few years have witnessed researches concerned by vertical axis wind turbine (VAWT) performance considering its advantages compared to the horizontal axis wind turbines, as it can be operated in urban areas without producing noise, ease of maintenance and simple construction, in addition to its low cost. More interest is growing in developing efficient clusters of VAWT in order to increase power generation at specific sites by using multiple turbines. In the present work, the performance of various configurations of Darrieus type VAWT clusters is examined using computational fluid dynamics (CFD) simulations. The objective of this work is to increase the overall power coefficient of the turbines cluster compared to single rotor performance. This objective shall be achieved by examining mutual interactions between rotors arranged in close proximity and examining the effect of oblique angle between rotors on overall performance of the cluster of rotors. The performance is assessed by observing the overall power coefficient of the cluster. Also, the velocity wake of the simulated three rotors turbine cases was analyzed and compared to the that of the single rotor.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"28 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":"115903398","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}
Operation and maintenance costs are a major driver for levelized cost of energy of wind power plants and can be reduced through optimized operation and maintenance practices accomplishable by various prognostics and health management (PHM) technologies. In recent years, the wind industry has become more open to adopting PHM solutions, especially those focusing on diagnostics. However, prognostics activities are, in general, still at the research and development stage. On the other hand, the industry has a request to estimate a component’s remaining useful life (RUL) when it has faulted, and this is a key output of prognostics. Systematically presenting PHM technologies to the wind industry by highlighting the RUL prediction need potentially helps speed up its acceptance and provides more benefits from PHM to the industry. In this paper, we introduce a PHM for wind framework. It highlights specifics unique to wind turbines and features integration of data and physics domain information and models. The output of the framework focuses on RUL prediction. To demonstrate its application, a data domain method for wind turbine gearbox fault diagnostics is presented. It uses supervisory control and data acquisition system time series data, normalizes gearbox temperature measurements with reference to environmental temperature and turbine power, and leverages big data analytics and machine-learning techniques to make the model scalable and the diagnostics process automatic. Another physics-domain modeling method for RUL prediction of wind turbine gearbox high-speed-stage bearings failed by axial cracks is also discussed. Bearing axial cracking has been shown to be the prevalent wind turbine gearbox failure mode experienced in the field and is different from rolling contact fatigue, which is targeted during the bearing design stage. The method uses probability of failure as a component reliability assessment and RUL prediction metric, which can be expanded to other drivetrain components or failure modes. The presented PHM for wind framework is generic and applicable to both land-based and offshore wind turbines.
{"title":"A Prognostics and Health Management Framework for Wind","authors":"S. Sheng, Yi-min Guo","doi":"10.1115/gt2019-91533","DOIUrl":"https://doi.org/10.1115/gt2019-91533","url":null,"abstract":"\u0000 Operation and maintenance costs are a major driver for levelized cost of energy of wind power plants and can be reduced through optimized operation and maintenance practices accomplishable by various prognostics and health management (PHM) technologies. In recent years, the wind industry has become more open to adopting PHM solutions, especially those focusing on diagnostics. However, prognostics activities are, in general, still at the research and development stage. On the other hand, the industry has a request to estimate a component’s remaining useful life (RUL) when it has faulted, and this is a key output of prognostics. Systematically presenting PHM technologies to the wind industry by highlighting the RUL prediction need potentially helps speed up its acceptance and provides more benefits from PHM to the industry. In this paper, we introduce a PHM for wind framework. It highlights specifics unique to wind turbines and features integration of data and physics domain information and models. The output of the framework focuses on RUL prediction. To demonstrate its application, a data domain method for wind turbine gearbox fault diagnostics is presented. It uses supervisory control and data acquisition system time series data, normalizes gearbox temperature measurements with reference to environmental temperature and turbine power, and leverages big data analytics and machine-learning techniques to make the model scalable and the diagnostics process automatic. Another physics-domain modeling method for RUL prediction of wind turbine gearbox high-speed-stage bearings failed by axial cracks is also discussed. Bearing axial cracking has been shown to be the prevalent wind turbine gearbox failure mode experienced in the field and is different from rolling contact fatigue, which is targeted during the bearing design stage. The method uses probability of failure as a component reliability assessment and RUL prediction metric, which can be expanded to other drivetrain components or failure modes. The presented PHM for wind framework is generic and applicable to both land-based and offshore wind turbines.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"7 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":"130750664","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}
The focus of this work is the influence of atomizing flow on a centrifugal compressor. First, the authors clarify that the performance of the centrifugal compressor under wet gas conditions decreases with the increase of LMF as a result of an increase to the impeller shaft power, as suggested in their previous report. A new method for predicting the compressor shaft power based on the liquid behavior in the impeller is then proposed. The authors hypothesize that the increment of the impeller shaft power under wet gas conditions is different when liquid film is dominant in the impeller than when liquid droplets are. In the previous report, the predicted shaft power under the condition that the liquid film was assumed to be dominant in the impeller was experimentally verified. This paper experimentally verifies the predicted shaft power under the condition that the liquid droplets are assumed to be dominant.
{"title":"Effect of Wet Gas Behavior on Centrifugal Compressor Shaft Power","authors":"D. Kawaguchi, Katsutoshi Kobayashi","doi":"10.1115/gt2019-91143","DOIUrl":"https://doi.org/10.1115/gt2019-91143","url":null,"abstract":"\u0000 The focus of this work is the influence of atomizing flow on a centrifugal compressor. First, the authors clarify that the performance of the centrifugal compressor under wet gas conditions decreases with the increase of LMF as a result of an increase to the impeller shaft power, as suggested in their previous report. A new method for predicting the compressor shaft power based on the liquid behavior in the impeller is then proposed. The authors hypothesize that the increment of the impeller shaft power under wet gas conditions is different when liquid film is dominant in the impeller than when liquid droplets are. In the previous report, the predicted shaft power under the condition that the liquid film was assumed to be dominant in the impeller was experimentally verified. This paper experimentally verifies the predicted shaft power under the condition that the liquid droplets are assumed to be dominant.","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":"130834973","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}
L. Cowell, J. Roesch, Alejandro Camou, Timothy Caron, J. Ritchie, I. Carlos
The importance of expanded operating flexibility with reduced emissions on dry low emissions (DLE) gas turbines to lower loads has grown in importance for operators in many applications including natural gas transmission. Solar Turbines has developed an improved emissions control algorithm for Solar’s SoloNOx DLE gas turbines being offered as Enhanced Emissions Control. The new algorithm reduces carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions from idle to 50% load. The corresponding startup and shut down emissions are reduced so that operators can obtain permits for operation over longer periods outside of low emissions mode. The algorithm has been evaluated in field trials at two different compressor stations using different gas turbine engine models. Solar’s Taurus™ 60 was tested at a field site in West Virginia and a Mars® 100 was tested near Houston, Texas in the United States. The new control scheme reduces emissions from part load down to idle. The new controls extend the bleed valve or variable guide vanes’ operating range where they modulate to control combustor temperature from idle to full load. The pilot fuel schedule is also changed to work more directly with the combustor temperature control. Two field trials were completed to measure emissions continuously for more than 10 months at each site to validate the effectiveness of the new algorithm. Operation of the test units was largely at loads over 50% and the continuous data served to validate that the new algorithm with the modifications to pilot control did not change the emissions signature in the ‘low emissions mode.” In addition, multiple site visits were completed to map emissions from idle to 50% load over a range of engine settings. This mapping fully documented the complete emissions performance of the test units from idle to 100% load over a range of ambient temperatures from below freezing to 38°C. The field trials validate that the improved controls reduce CO and UHC emissions from idle to 50% load when compared to the current production algorithm. The testing also validated that the emissions above 50% load were unchanged compared to the current control algorithm. Specifically, CO and UHC emissions were reduced by 35 to 99% over the idle to 50% load operating range. By optimizing the pilot fuel controls the NOx emissions were also reduced 20 to 75% from idle to 50% load. The algorithm makes it possible to offer 15 ppm NOx warranties for the subject engine models in gas transmission applications down to 40% load that have been restricted to 50% load and higher. Over the wide ambient temperature range experienced during the field trial periods, emissions were consistent and no clear trends were documented with ambient temperature or engine speed (load).
{"title":"Field Qualification of an Improved DLE Gas Turbine Control Algorithm to Reduce Part Load Emissions","authors":"L. Cowell, J. Roesch, Alejandro Camou, Timothy Caron, J. Ritchie, I. Carlos","doi":"10.1115/gt2019-91053","DOIUrl":"https://doi.org/10.1115/gt2019-91053","url":null,"abstract":"\u0000 The importance of expanded operating flexibility with reduced emissions on dry low emissions (DLE) gas turbines to lower loads has grown in importance for operators in many applications including natural gas transmission. Solar Turbines has developed an improved emissions control algorithm for Solar’s SoloNOx DLE gas turbines being offered as Enhanced Emissions Control. The new algorithm reduces carbon monoxide (CO) and unburned hydrocarbons (UHC) emissions from idle to 50% load. The corresponding startup and shut down emissions are reduced so that operators can obtain permits for operation over longer periods outside of low emissions mode. The algorithm has been evaluated in field trials at two different compressor stations using different gas turbine engine models. Solar’s Taurus™ 60 was tested at a field site in West Virginia and a Mars® 100 was tested near Houston, Texas in the United States. The new control scheme reduces emissions from part load down to idle. The new controls extend the bleed valve or variable guide vanes’ operating range where they modulate to control combustor temperature from idle to full load. The pilot fuel schedule is also changed to work more directly with the combustor temperature control.\u0000 Two field trials were completed to measure emissions continuously for more than 10 months at each site to validate the effectiveness of the new algorithm. Operation of the test units was largely at loads over 50% and the continuous data served to validate that the new algorithm with the modifications to pilot control did not change the emissions signature in the ‘low emissions mode.” In addition, multiple site visits were completed to map emissions from idle to 50% load over a range of engine settings. This mapping fully documented the complete emissions performance of the test units from idle to 100% load over a range of ambient temperatures from below freezing to 38°C.\u0000 The field trials validate that the improved controls reduce CO and UHC emissions from idle to 50% load when compared to the current production algorithm. The testing also validated that the emissions above 50% load were unchanged compared to the current control algorithm. Specifically, CO and UHC emissions were reduced by 35 to 99% over the idle to 50% load operating range. By optimizing the pilot fuel controls the NOx emissions were also reduced 20 to 75% from idle to 50% load. The algorithm makes it possible to offer 15 ppm NOx warranties for the subject engine models in gas transmission applications down to 40% load that have been restricted to 50% load and higher. Over the wide ambient temperature range experienced during the field trial periods, emissions were consistent and no clear trends were documented with ambient temperature or engine speed (load).","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"6 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":"131580427","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}
Deepak Trivedi, R. A. Bidkar, C. Wolfe, J. Mortzheim
Fluid film stiffness is a key design parameter for film-riding seals — a large positive film stiffness ensures stable seal operation with the seal faithfully tracking the rotor in the presence of varying inertial and friction loads. A hydrostatic supercritical CO2 (sCO2) film-riding seal relies on feed ports pressurized with sCO2 to generate film stiffness needed for reliable seal operation. The high-pressure supercritical CO2 expands to lower pressures through the seal bearing face, and during this expansion, undergoes large temperature changes along with a phase change to gaseous state and possibly liquid state. These large temperature changes and phase changes are important design considerations specific to sCO2 as the working fluid. From this perspective, film-stiffness test data with sCO2 as the working fluid is valuable for both understanding the physics as well as for validating the predictions of computational fluid dynamics (CFD) models of sCO2 expansion across a seal bearing face. In prior work, we described a non-rotating stiffness test rig for characterizing fluid film stiffness and presented air-based test data with the rig. In this paper, we present sCO2-based data obtained by connecting this previously described stiffness rig to a newly commissioned sCO2 flow loop (flow rate about 0.1 kg/s, pressures up to 16.5 MPa, temperatures up to 464 K). The test data presented in this paper include seal bearing pressures and fluid/metal temperatures for varying film thickness, seal bearing face tilt and inlet/supply pressures. The test data show significant temperature reduction as the supercritical flow expands across the seal bearing face. The measured bearing pressure was compared with the predictions of a 3D CFD model with real gas CO2 properties, with about 4% error between the measurements and the predictions. The sCO2-based test data in this work and the air-based test data from prior work are used to calculate fluid film stiffness over a range of film thicknesses. It is seen that the sCO2-based data and air-based data tend to collapse on a normalized stiffness curve, which is characteristic of the bearing geometry. Moreover, it is seen that the hydrostatic seal film stiffness generally scales with the supply pressure and can be adjusted to high stiffness values typically expected in hydrodynamic film-riding seals.
{"title":"Supercritical CO2 Tests for Hydrostatic Film Stiffness in Film-Riding Seals","authors":"Deepak Trivedi, R. A. Bidkar, C. Wolfe, J. Mortzheim","doi":"10.1115/gt2019-90975","DOIUrl":"https://doi.org/10.1115/gt2019-90975","url":null,"abstract":"\u0000 Fluid film stiffness is a key design parameter for film-riding seals — a large positive film stiffness ensures stable seal operation with the seal faithfully tracking the rotor in the presence of varying inertial and friction loads. A hydrostatic supercritical CO2 (sCO2) film-riding seal relies on feed ports pressurized with sCO2 to generate film stiffness needed for reliable seal operation. The high-pressure supercritical CO2 expands to lower pressures through the seal bearing face, and during this expansion, undergoes large temperature changes along with a phase change to gaseous state and possibly liquid state. These large temperature changes and phase changes are important design considerations specific to sCO2 as the working fluid. From this perspective, film-stiffness test data with sCO2 as the working fluid is valuable for both understanding the physics as well as for validating the predictions of computational fluid dynamics (CFD) models of sCO2 expansion across a seal bearing face. In prior work, we described a non-rotating stiffness test rig for characterizing fluid film stiffness and presented air-based test data with the rig. In this paper, we present sCO2-based data obtained by connecting this previously described stiffness rig to a newly commissioned sCO2 flow loop (flow rate about 0.1 kg/s, pressures up to 16.5 MPa, temperatures up to 464 K). The test data presented in this paper include seal bearing pressures and fluid/metal temperatures for varying film thickness, seal bearing face tilt and inlet/supply pressures. The test data show significant temperature reduction as the supercritical flow expands across the seal bearing face. The measured bearing pressure was compared with the predictions of a 3D CFD model with real gas CO2 properties, with about 4% error between the measurements and the predictions. The sCO2-based test data in this work and the air-based test data from prior work are used to calculate fluid film stiffness over a range of film thicknesses. It is seen that the sCO2-based data and air-based data tend to collapse on a normalized stiffness curve, which is characteristic of the bearing geometry. Moreover, it is seen that the hydrostatic seal film stiffness generally scales with the supply pressure and can be adjusted to high stiffness values typically expected in hydrodynamic film-riding seals.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"64 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":"115292055","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}
Stefan D. Cich, J. Moore, Meera Day Towler, J. Mortzheim, D. Hofer
Recent testing has been performed on a 1 MWe sCO2 closed loop recuperated cycle under funding from the US DOE Sunshot initiative and industry partners. Some of the goals of this funding included the development of a 1 MWe loop, a 10 MWe turbine, and performance and mechanical testing. One of the key challenges that presented itself was the filling, start-up, and shut down of the entire system. Understanding the loop transient performance is important when having to bring a turbine online, transitioning from peak to partial loading, and also managing routine and emergency shut downs. Due to large changes in density near the critical point for CO2 and its tendency to form dry ice when expanded to atmospheric pressure, managing loop filling and venting is critical in ensuring that components do not get damaged. Specific challenges were centered on protecting the dry gas seals, maintaining proper mass in the loop, and also thermal transients during trips. This paper will take a detailed look at the challenges encountered during start up and shut downs, and also the solutions that were implemented to successful transition between different phases of the testing.
{"title":"Loop Filling and Start Up With a Closed Loop sCO2 Brayton Cycle","authors":"Stefan D. Cich, J. Moore, Meera Day Towler, J. Mortzheim, D. Hofer","doi":"10.1115/gt2019-90393","DOIUrl":"https://doi.org/10.1115/gt2019-90393","url":null,"abstract":"\u0000 Recent testing has been performed on a 1 MWe sCO2 closed loop recuperated cycle under funding from the US DOE Sunshot initiative and industry partners. Some of the goals of this funding included the development of a 1 MWe loop, a 10 MWe turbine, and performance and mechanical testing. One of the key challenges that presented itself was the filling, start-up, and shut down of the entire system. Understanding the loop transient performance is important when having to bring a turbine online, transitioning from peak to partial loading, and also managing routine and emergency shut downs. Due to large changes in density near the critical point for CO2 and its tendency to form dry ice when expanded to atmospheric pressure, managing loop filling and venting is critical in ensuring that components do not get damaged. Specific challenges were centered on protecting the dry gas seals, maintaining proper mass in the loop, and also thermal transients during trips. This paper will take a detailed look at the challenges encountered during start up and shut downs, and also the solutions that were implemented to successful transition between different phases of the testing.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"55 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":"114387138","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}
Natural gas production has increased dramatically in recent years due to advances in horizontal drilling and hydraulic fracturing techniques. There are still challenges that must be addressed by industry to better utilize these abundant natural gas resources. For example, due to the cost and complexity with piping installations from remote well sites to processing facilities (should they exist), natural gas is often flared at the site whereas the liquid hydrocarbons are stored in holding tanks. For the natural gas that is recovered and processed, there are currently economic benefits to exporting the gas to international markets, provided that the gas can be liquefied and shipped. While the number of liquefaction facilities has increased in recent years, additional liquefaction plants are needed. This paper introduces a novel liquefaction cycle that utilizes a supercritical carbon dioxide (sCO2) power cycle to provide power and initial stages of refrigeration to a natural gas liquefaction cycle. The liquefaction cycle uses a flow of CO2 extracted from the power cycle as well as natural gas to provide several stages of refrigeration capable of liquefying the process stream. The combined sCO2 power and liquefaction cycle is described in detail and initial cycle analyses are presented. The cycle performance is compared to small-scale natural gas liquefaction cycles and is shown to provide comparable performance to the reviewed cycles. Due to the compact nature of the sCO2 power cycle equipment, the sCO2 liquefaction cycle described herein can provide small, modular liquefaction plants that can be employed at individual well sites to liquefy and store the natural gas as opposed to flaring the gas.
{"title":"A Supercritical CO2 Combined Power and Liquefaction Cycle","authors":"Griffin C. Beck, D. Ransom, K. Hoopes","doi":"10.1115/gt2019-91371","DOIUrl":"https://doi.org/10.1115/gt2019-91371","url":null,"abstract":"\u0000 Natural gas production has increased dramatically in recent years due to advances in horizontal drilling and hydraulic fracturing techniques. There are still challenges that must be addressed by industry to better utilize these abundant natural gas resources. For example, due to the cost and complexity with piping installations from remote well sites to processing facilities (should they exist), natural gas is often flared at the site whereas the liquid hydrocarbons are stored in holding tanks.\u0000 For the natural gas that is recovered and processed, there are currently economic benefits to exporting the gas to international markets, provided that the gas can be liquefied and shipped. While the number of liquefaction facilities has increased in recent years, additional liquefaction plants are needed.\u0000 This paper introduces a novel liquefaction cycle that utilizes a supercritical carbon dioxide (sCO2) power cycle to provide power and initial stages of refrigeration to a natural gas liquefaction cycle. The liquefaction cycle uses a flow of CO2 extracted from the power cycle as well as natural gas to provide several stages of refrigeration capable of liquefying the process stream. The combined sCO2 power and liquefaction cycle is described in detail and initial cycle analyses are presented. The cycle performance is compared to small-scale natural gas liquefaction cycles and is shown to provide comparable performance to the reviewed cycles. Due to the compact nature of the sCO2 power cycle equipment, the sCO2 liquefaction cycle described herein can provide small, modular liquefaction plants that can be employed at individual well sites to liquefy and store the natural gas as opposed to flaring the gas.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"242 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":"133931408","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 study provides a novel contribution towards the establishment of a new high–fidelity simulation–based design methodology for stall–regulated horizontal axis wind turbines. The aerodynamic design of these machines is complex, due to the difficulty of reliably predicting stall onset and post–stall characteristics. Low–fidelity design methods, widely used in industry, are computationally efficient, but are often affected by significant uncertainty. Conversely, Navier–Stokes CFD can reduce such uncertainty, resulting in lower development costs by reducing the need of field testing of designs not fit for purpose. Here, the compressible CFD research code COSA is used to assess the performance of two alternative designs of a 13–meter stall–regulated rotor over a wide range of operating conditions. Validation of the numerical methodology is based on thorough comparisons of novel simulations and measured data of the NREL Phase VI turbine rotor, and one of the two industrial rotor designs. An excellent agreement is found in all cases. All simulations of the two industrial rotors are time–dependent, to capture the unsteadiness associated with stall which occurs at most wind speeds. The two designs are cross-compared, with emphasis on the different stall patterns resulting from particular design choices. The key novelty of this work is the CFD–based assessment of the correlation among turbine power, blade aerodynamics, and blade design variables (airfoil geometry, blade planform and twist) over most operational wind speeds.
{"title":"Assessing the Sensitivity of Stall-Regulated Wind Turbine Power to Blade Design Using High-Fidelity CFD","authors":"A. Sanvito, G. Persico, M. Campobasso","doi":"10.1115/GT2019-90956","DOIUrl":"https://doi.org/10.1115/GT2019-90956","url":null,"abstract":"\u0000 This study provides a novel contribution towards the establishment of a new high–fidelity simulation–based design methodology for stall–regulated horizontal axis wind turbines. The aerodynamic design of these machines is complex, due to the difficulty of reliably predicting stall onset and post–stall characteristics. Low–fidelity design methods, widely used in industry, are computationally efficient, but are often affected by significant uncertainty. Conversely, Navier–Stokes CFD can reduce such uncertainty, resulting in lower development costs by reducing the need of field testing of designs not fit for purpose. Here, the compressible CFD research code COSA is used to assess the performance of two alternative designs of a 13–meter stall–regulated rotor over a wide range of operating conditions. Validation of the numerical methodology is based on thorough comparisons of novel simulations and measured data of the NREL Phase VI turbine rotor, and one of the two industrial rotor designs. An excellent agreement is found in all cases. All simulations of the two industrial rotors are time–dependent, to capture the unsteadiness associated with stall which occurs at most wind speeds. The two designs are cross-compared, with emphasis on the different stall patterns resulting from particular design choices. The key novelty of this work is the CFD–based assessment of the correlation among turbine power, blade aerodynamics, and blade design variables (airfoil geometry, blade planform and twist) over most operational wind speeds.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"100 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":"122106260","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. Sathish, Pramod Kumar, Adi Narayana Namburi, Lokesh Swami, C. Fuetterer, P. Gopi
The axial sCO2 turbine design for shaft power above 10 MW can be approached in a manner similar to the High Pressure (HP), backpressure steam turbine. Starting from the overall performance specification, the detailed turbine design is carried out in steps; 1-Dimensional (1D) meanline design, Quasi 3D (Q3D) throughflow design, cascade blade-to-blade design, 3-Dimensional (3D) blade design, stress and vibration analysis. These design steps are well established and validated, using dedicated test rigs and field performance measurements, for the steam turbines. Even though detailed validation tests are not available for axial sCO2 turbines, there exists a scope to utilize the established steam turbine design principles. This paper highlights sCO2 turbine design procedure through a 10 MW turbine design case study for Waste Heat Recovery (WHR) power plant. The focus areas are blade-to-blade design and stress analysis for which the challenges and novel approaches to design are elucidated. Classical blade design typically relies on expert knowledge where the 2D blade profile geometry is successively iterated to minimize the profile loss. Automated optimization routines are also employed by geometry parametrization techniques such as Bezier or B-Spline control points. This paper introduces a novel approach to 2D blade design as applied to a sCO2 turbine through a combination of Kulfan Class Shape Transformation (CST) for blade parametrization and unique optimization constraints to mimic the expert knowledge. The high power density of sCO2 turbomachinery while advantageous for weight and footprint reduction poses significant challenge in mechanical design. The overall power is distributed among few stages resulting in higher blade stress compared to an equivalent steam turbine. Increasing the blade chord, alternative root design are some of the mitigation methods to deal with the increased stress. They however lead to compromise in aerodynamic performance due to reduced blade aspect ratio. This necessitates novel approaches to balance mechanical and aerodynamic design, which are considered in this paper. Through a 10 MW sCO2 axial turbine design case study, this paper brings to the fore certain design challenges as compared to a conventional steam turbine and puts forth novel approaches to overcome the identified challenges.
轴功率大于10mw的轴向sCO2涡轮设计可以采用类似于高压(HP)背压汽轮机的方式。从总体性能指标出发，分步骤进行涡轮详细设计;一维(1D)平均线设计、准三维(Q3D)通流设计、叶栅叶片对叶片设计、三维(3D)叶片设计、应力和振动分析。这些设计步骤已经很好地建立和验证，使用专用的测试平台和现场性能测量，用于蒸汽轮机。尽管轴向sCO2涡轮机没有详细的验证试验，但存在利用既定汽轮机设计原则的范围。本文通过对余热回收(WHR)电厂10mw汽轮机的设计案例研究，重点介绍了sCO2汽轮机的设计过程。重点领域是叶片对叶片的设计和应力分析，其中的挑战和新的设计方法是阐明。经典的叶片设计通常依赖于专家知识，其中连续迭代二维叶片轮廓几何以最大限度地减少轮廓损失。几何参数化技术如Bezier或b样条控制点也采用了自动优化例程。本文介绍了一种新的二维叶片设计方法，并将Kulfan Class Shape Transformation (CST)技术用于叶片参数化和独特的优化约束来模拟专家知识，应用于sCO2涡轮。sCO2涡轮机械的高功率密度同时又有利于减轻重量和减少占地面积，这对机械设计提出了重大挑战。总功率分布在几个阶段导致更高的叶片应力相比，一个等效的汽轮机。增加叶弦、替代根设计是应对应力增加的一些缓解方法。然而，由于叶片展弦比降低，它们导致空气动力学性能的妥协。这需要新的方法来平衡机械和气动设计，这是本文所考虑的。通过一个10 MW sCO2轴向汽轮机的设计案例研究，本文提出了与传统汽轮机相比的一些设计挑战，并提出了克服这些挑战的新方法。
{"title":"Novel Approaches for sCO2 Axial Turbine Design","authors":"S. Sathish, Pramod Kumar, Adi Narayana Namburi, Lokesh Swami, C. Fuetterer, P. Gopi","doi":"10.1115/gt2019-90606","DOIUrl":"https://doi.org/10.1115/gt2019-90606","url":null,"abstract":"\u0000 The axial sCO2 turbine design for shaft power above 10 MW can be approached in a manner similar to the High Pressure (HP), backpressure steam turbine. Starting from the overall performance specification, the detailed turbine design is carried out in steps; 1-Dimensional (1D) meanline design, Quasi 3D (Q3D) throughflow design, cascade blade-to-blade design, 3-Dimensional (3D) blade design, stress and vibration analysis. These design steps are well established and validated, using dedicated test rigs and field performance measurements, for the steam turbines. Even though detailed validation tests are not available for axial sCO2 turbines, there exists a scope to utilize the established steam turbine design principles. This paper highlights sCO2 turbine design procedure through a 10 MW turbine design case study for Waste Heat Recovery (WHR) power plant. The focus areas are blade-to-blade design and stress analysis for which the challenges and novel approaches to design are elucidated.\u0000 Classical blade design typically relies on expert knowledge where the 2D blade profile geometry is successively iterated to minimize the profile loss. Automated optimization routines are also employed by geometry parametrization techniques such as Bezier or B-Spline control points. This paper introduces a novel approach to 2D blade design as applied to a sCO2 turbine through a combination of Kulfan Class Shape Transformation (CST) for blade parametrization and unique optimization constraints to mimic the expert knowledge.\u0000 The high power density of sCO2 turbomachinery while advantageous for weight and footprint reduction poses significant challenge in mechanical design. The overall power is distributed among few stages resulting in higher blade stress compared to an equivalent steam turbine. Increasing the blade chord, alternative root design are some of the mitigation methods to deal with the increased stress. They however lead to compromise in aerodynamic performance due to reduced blade aspect ratio. This necessitates novel approaches to balance mechanical and aerodynamic design, which are considered in this paper.\u0000 Through a 10 MW sCO2 axial turbine design case study, this paper brings to the fore certain design challenges as compared to a conventional steam turbine and puts forth novel approaches to overcome the identified challenges.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"11 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":"117177867","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：