The supercritical carbon dioxide (S-CO2) Brayton power cycle has been receiving worldwide attention due to the high thermal efficiency and compact system configuration. Because of the incompressible liquid like characteristic (e.g. high density, low compressibility) of the CO2 near the critical point (30.98 °C, 7.38MPa), an S-CO2 Brayton cycle can achieve high efficiency by reducing compression work. In order to utilize the S-CO2 power conversion technology in various applications, such as distributed power generation and marine propulsion, air-cooled waste heat removal system is necessary. However, the critical temperature of CO2 (30.98 °C) is an intrinsic limitation on the system minimum temperature. Because of the small difference with atmospheric temperature, a large amount of cooling air flow or a very large heat exchanger is required to reach the target minimum temperature. In this paper, to improve the system efficiency and ease the problem of air-cooled waste heat removal system, the mixture of supercritical CO2 with other fluids has been studied. Also, the preliminary performance test results of CO2 mixture with pre-existing experimental facility are evaluated.
{"title":"Preliminary Study of Supercritical CO2 Mixed With Gases for Power Cycle in Warm Environments","authors":"Seungjoon Baik, Jeong-Ik Lee","doi":"10.1115/GT2018-76386","DOIUrl":"https://doi.org/10.1115/GT2018-76386","url":null,"abstract":"The supercritical carbon dioxide (S-CO2) Brayton power cycle has been receiving worldwide attention due to the high thermal efficiency and compact system configuration. Because of the incompressible liquid like characteristic (e.g. high density, low compressibility) of the CO2 near the critical point (30.98 °C, 7.38MPa), an S-CO2 Brayton cycle can achieve high efficiency by reducing compression work. In order to utilize the S-CO2 power conversion technology in various applications, such as distributed power generation and marine propulsion, air-cooled waste heat removal system is necessary. However, the critical temperature of CO2 (30.98 °C) is an intrinsic limitation on the system minimum temperature. Because of the small difference with atmospheric temperature, a large amount of cooling air flow or a very large heat exchanger is required to reach the target minimum temperature. In this paper, to improve the system efficiency and ease the problem of air-cooled waste heat removal system, the mixture of supercritical CO2 with other fluids has been studied. Also, the preliminary performance test results of CO2 mixture with pre-existing experimental facility are evaluated.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114097737","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}
C. Meher-Homji, Matt Taher, Feroze J. Meher-Homji, Pradeep T. Pillai
Over the last 50 years of the LNG industry, there has been a significant evolution in the drivers used to power liquefaction compressors. For several decades, steam turbines were utilized and the first gas turbines were deployed in 1969. In a LNG liquefaction plant, the gas turbine drivers and refrigeration compressors strongly influence overall plant performance and efficiency. After the first Aeroderivative solution was applied at Darwin LNG in 2006, there has been a significant growth in the application of these engines for LNG mechanical drive. This trend is driven by the need to reduce greenhouse gas emissions, and fuel auto-consumption, which in a feed gas constrained situation, boosts LNG output. Aeroderivatives tends to increase plant availability. This paper reviews the market penetration of Aeroderivatives into the LNG liquefaction sector highlighting the fundamental differences between Aeroderivative, and heavy duty engines. The background, historical deployment and technical issues relating to the use of Aeroderivative engines for LNG mechanical drive are addressed. Qualification programs for new engines and technologies such as inlet chilling for power augmentation as implemented in LNG plants are reviewed.
{"title":"Aeroderivative Engines in LNG Liquefaction Mechanical Drive Applications","authors":"C. Meher-Homji, Matt Taher, Feroze J. Meher-Homji, Pradeep T. Pillai","doi":"10.1115/GT2018-75567","DOIUrl":"https://doi.org/10.1115/GT2018-75567","url":null,"abstract":"Over the last 50 years of the LNG industry, there has been a significant evolution in the drivers used to power liquefaction compressors. For several decades, steam turbines were utilized and the first gas turbines were deployed in 1969. In a LNG liquefaction plant, the gas turbine drivers and refrigeration compressors strongly influence overall plant performance and efficiency. After the first Aeroderivative solution was applied at Darwin LNG in 2006, there has been a significant growth in the application of these engines for LNG mechanical drive. This trend is driven by the need to reduce greenhouse gas emissions, and fuel auto-consumption, which in a feed gas constrained situation, boosts LNG output. Aeroderivatives tends to increase plant availability. This paper reviews the market penetration of Aeroderivatives into the LNG liquefaction sector highlighting the fundamental differences between Aeroderivative, and heavy duty engines. The background, historical deployment and technical issues relating to the use of Aeroderivative engines for LNG mechanical drive are addressed. Qualification programs for new engines and technologies such as inlet chilling for power augmentation as implemented in LNG plants are reviewed.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131389901","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 Supercritical CO2 power cycle (S-CO2 cycle) is the power cycle that adopts CO2 as a working fluid and is designed to have a compression process near the critical point of CO2. Due to the non-linearity of CO2 pyhsical properties near the critical point, the S-CO2 cycle needs relatively less compression work. Therefore, the efficiency of the S-CO2 cycle is higher than traditional gas cycles. Furthermore, because of the relatively high system minimum pressure (near the critical point, ∼7.39 MPa), an S-CO2 cycle can be composed of smaller turbomachines. Considering these advantages, nowadays, there are many attempts to apply S-CO2 cycles to various fields, such as waste heat recovery, nuclear, coal, concentrated solar power plant and so on. These non-linear pyhsical properties become the cause of some unique issues. One of the most significant issues is the internal pinch point problem in a recuperator. Unlike the traditional gas-to-gas heat exchanger, each hot and cold side of the S-CO2 recuperator goes through the severe change of specific heat. This dramatic change of specific heat may cause the internal pinch point of the recuperator. When the internal pinch point phenomenon occurs, the performance of the recuperator may not able to be evaluated from the pre-fixed effectiveness. This can be an issue when the compressor inlet temperature decreases to transcritical or subcritical region. This may alter the optimal point of the S-CO2 power cycle. In this paper, optimal design points and optimal performance of the S-CO2 power cycle are tracked with the consideration of the internal pinch point phenomenon. While changing the system boundary conditions, the optimal point variation due to internal pinch point phenomenon is evaluated and compared with a traditional methodology. This research is progressed with an in-house integrated S-CO2 power cycle analysis code, which is named KAIST – ESCA (Evaluator for Supercritical CO2 Cycle based on Adjoint method). The target cycle layouts are Simple Recuperated, Intercooling, Recompression and Recompression with intercooling layouts. Both of the S-CO2 Rankine and Brayton cycles conditions are considered.
{"title":"Evaluation of the Optimal Point Variation of the S-CO2 Cycle While Considering Internal Pinch in Recuperator","authors":"Seongmin Son, J. Heo, Jeong-Ik Lee","doi":"10.1115/GT2018-75196","DOIUrl":"https://doi.org/10.1115/GT2018-75196","url":null,"abstract":"The Supercritical CO2 power cycle (S-CO2 cycle) is the power cycle that adopts CO2 as a working fluid and is designed to have a compression process near the critical point of CO2. Due to the non-linearity of CO2 pyhsical properties near the critical point, the S-CO2 cycle needs relatively less compression work. Therefore, the efficiency of the S-CO2 cycle is higher than traditional gas cycles. Furthermore, because of the relatively high system minimum pressure (near the critical point, ∼7.39 MPa), an S-CO2 cycle can be composed of smaller turbomachines. Considering these advantages, nowadays, there are many attempts to apply S-CO2 cycles to various fields, such as waste heat recovery, nuclear, coal, concentrated solar power plant and so on. These non-linear pyhsical properties become the cause of some unique issues. One of the most significant issues is the internal pinch point problem in a recuperator. Unlike the traditional gas-to-gas heat exchanger, each hot and cold side of the S-CO2 recuperator goes through the severe change of specific heat. This dramatic change of specific heat may cause the internal pinch point of the recuperator. When the internal pinch point phenomenon occurs, the performance of the recuperator may not able to be evaluated from the pre-fixed effectiveness. This can be an issue when the compressor inlet temperature decreases to transcritical or subcritical region. This may alter the optimal point of the S-CO2 power cycle. In this paper, optimal design points and optimal performance of the S-CO2 power cycle are tracked with the consideration of the internal pinch point phenomenon. While changing the system boundary conditions, the optimal point variation due to internal pinch point phenomenon is evaluated and compared with a traditional methodology. This research is progressed with an in-house integrated S-CO2 power cycle analysis code, which is named KAIST – ESCA (Evaluator for Supercritical CO2 Cycle based on Adjoint method). The target cycle layouts are Simple Recuperated, Intercooling, Recompression and Recompression with intercooling layouts. Both of the S-CO2 Rankine and Brayton cycles conditions are considered.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133604356","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 characteristics of a transparent centrifugal pump of radial type were investigated for different conditions when conveying two-phase (air/water) flows. A closed impeller and a geometrically similar semi-open impeller, both made out of acrylic glass, were employed for comparison purposes when increasing air loading. The performance of the pump was measured for either a constant gas volume fraction or a constant air flow rate at the pump inlet. Hysteresis effects were studied by considering three different experimental approaches to reach the desired operating conditions. A constant rotational speed of 650 rpm was set for all experiments. The whole system was made of transparent acrylic glass to allow high-quality flow visualization. A systematic experimental database was produced based on shadowgraphy imaging, so that the resulting two-phase regimes could be properly identified. The results show that for gas volume fractions between 1 and 3%, the deterioration of pump performance parameters is much lower in the semi-open impeller compared to that of the closed impeller. Nevertheless, in the gas volume fraction range between 4 and 6%, the trend is reversed; the semi-open impeller performance is reduced compared to the closed impeller, particularly in overload conditions. At even higher gas loading, the semi-open impeller shows again superior performance. Flow instabilities and pump surging were much stronger in the closed impeller. The main reason for that was the occurrence of alternating gas pockets on the blades of the closed impeller. Additionally, pump surging was observed only in a very limited range of flow conditions in the semi-open impeller. Comparing the different experimental procedures to set the desired flow conditions, no significant hysteresis effects could be observed in the closed impeller. However, in the semi-open impeller obvious hysteresis in the performance could be seen for gas volume fractions between 4 and 6%. All the obtained experimental results will be useful to check and validate computational models used for CFD in a comparison study.
{"title":"Experimental Study of Two-Phase Air/Water Flow in a Centrifugal Pump Working With a Closed or a Semi-Open Impeller","authors":"M. Mansour, Bernd Wunderlich, D. Thévenin","doi":"10.1115/GT2018-75380","DOIUrl":"https://doi.org/10.1115/GT2018-75380","url":null,"abstract":"The characteristics of a transparent centrifugal pump of radial type were investigated for different conditions when conveying two-phase (air/water) flows. A closed impeller and a geometrically similar semi-open impeller, both made out of acrylic glass, were employed for comparison purposes when increasing air loading. The performance of the pump was measured for either a constant gas volume fraction or a constant air flow rate at the pump inlet. Hysteresis effects were studied by considering three different experimental approaches to reach the desired operating conditions. A constant rotational speed of 650 rpm was set for all experiments. The whole system was made of transparent acrylic glass to allow high-quality flow visualization. A systematic experimental database was produced based on shadowgraphy imaging, so that the resulting two-phase regimes could be properly identified. The results show that for gas volume fractions between 1 and 3%, the deterioration of pump performance parameters is much lower in the semi-open impeller compared to that of the closed impeller. Nevertheless, in the gas volume fraction range between 4 and 6%, the trend is reversed; the semi-open impeller performance is reduced compared to the closed impeller, particularly in overload conditions. At even higher gas loading, the semi-open impeller shows again superior performance. Flow instabilities and pump surging were much stronger in the closed impeller. The main reason for that was the occurrence of alternating gas pockets on the blades of the closed impeller. Additionally, pump surging was observed only in a very limited range of flow conditions in the semi-open impeller. Comparing the different experimental procedures to set the desired flow conditions, no significant hysteresis effects could be observed in the closed impeller. However, in the semi-open impeller obvious hysteresis in the performance could be seen for gas volume fractions between 4 and 6%. All the obtained experimental results will be useful to check and validate computational models used for CFD in a comparison study.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"95 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114606872","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}
K. Manikantachari, Scott Martin, L. Vesely, Jose Bobren-Diaz, Subith S. Vasu, J. Kapat
The sCO2 power cycle concept is identified as a potentially efficient, economical, and pollutant free power generation technique for future power generation. Recent work in the literature provides some strategies and best operating conditions for direct-fired sCO2 combustors based on zero-dimensional reactor modeling analysis, however there is a need for a detailed investigation using accurate combustion chemical kinetics and thermophysical models. Here, the sCO2 combustor is modelled by coupling perfectly stirred reactor (PSR) and plug flow reactor (PFR) models. The real gas effects are incorporated using the Soave-Redlich-Kwong (SRK) equation of state. Also, the detailed Aramco 2.0 kinetic mechanism is used for the combustion kinetic rates. It is found that the primary zone must be diluted either with thirty or forty-five percent of the total CO2 in the cycle to have a feasible combustor design. However, the forty-five percent dilution level at 950 K and 1000 K yielded a better consumption of CO, O2 and CH4. Also, the cross-sectional area of the sCO2 combustor can be scaled-down to 10 to 20 times smaller than a traditional combustor with the same power output. Further, from this investigation, it is also recommended to have a gradually increasing secondary dilution in the dilution zone, by using progressively larger diameter holes. This design would help retain relatively high temperature in the initial portion of the dilution zone and would help consume fuel species such as, CO and CH4. It appears that, for sCO2 combustors “lean burn” is the better strategy over stoichiometric burning to eliminate CO build up at the combustor exit. The lean burn condition at equivalence ratio (ϕ) equal to 0.9 is recommended for sCO2 combustor operation. Also, the length of the dilution zone can be scaled-down to 50% by lean burn operation of the combustor. It is also observed that the lean burn increases the net turbine power. Current work provides crucial design considerations for the development of advanced sCO2 combustors to be used with direct-fired power cycles.
{"title":"A Strategy of Reactant Mixing in Methane Direct-Fired sCO2 Combustors","authors":"K. Manikantachari, Scott Martin, L. Vesely, Jose Bobren-Diaz, Subith S. Vasu, J. Kapat","doi":"10.1115/GT2018-75547","DOIUrl":"https://doi.org/10.1115/GT2018-75547","url":null,"abstract":"The sCO2 power cycle concept is identified as a potentially efficient, economical, and pollutant free power generation technique for future power generation. Recent work in the literature provides some strategies and best operating conditions for direct-fired sCO2 combustors based on zero-dimensional reactor modeling analysis, however there is a need for a detailed investigation using accurate combustion chemical kinetics and thermophysical models. Here, the sCO2 combustor is modelled by coupling perfectly stirred reactor (PSR) and plug flow reactor (PFR) models. The real gas effects are incorporated using the Soave-Redlich-Kwong (SRK) equation of state. Also, the detailed Aramco 2.0 kinetic mechanism is used for the combustion kinetic rates.\u0000 It is found that the primary zone must be diluted either with thirty or forty-five percent of the total CO2 in the cycle to have a feasible combustor design. However, the forty-five percent dilution level at 950 K and 1000 K yielded a better consumption of CO, O2 and CH4. Also, the cross-sectional area of the sCO2 combustor can be scaled-down to 10 to 20 times smaller than a traditional combustor with the same power output. Further, from this investigation, it is also recommended to have a gradually increasing secondary dilution in the dilution zone, by using progressively larger diameter holes. This design would help retain relatively high temperature in the initial portion of the dilution zone and would help consume fuel species such as, CO and CH4.\u0000 It appears that, for sCO2 combustors “lean burn” is the better strategy over stoichiometric burning to eliminate CO build up at the combustor exit. The lean burn condition at equivalence ratio (ϕ) equal to 0.9 is recommended for sCO2 combustor operation. Also, the length of the dilution zone can be scaled-down to 50% by lean burn operation of the combustor. It is also observed that the lean burn increases the net turbine power. Current work provides crucial design considerations for the development of advanced sCO2 combustors to be used with direct-fired power cycles.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128815236","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}
Meera Day Towler, T. Allison, P. Krueger, Karl D. Wygant
This investigation studies fast-response pressure measurements as an indicator of the onset of surge in a single-stage centrifugal compressor. The objective is to determine an online monitoring approach for surge control that does not rely on surge margin relative to maps from predictions or factory testing. Fast-response pressure transducers are installed in the suction piping, inducer, diffuser, and discharge piping. A speed line is mapped, and high-speed pressure data are collected across the compressor map. The compressor is driven into surge several times to collect pressure data between during surge and between surge events. Following testing, these data are post-processed via filtration and statistical analyses. It is determined that, when taken together, the mean and range of the standard deviation of the time signal for multiple time steps can be used to determine whether the compressor’s operating point is approaching surge for the conditions tested.
{"title":"A Novel Approach to Surge Control: High-Frequency Pressure Variance As an Indicator of Impending Surge in Centrifugal Compressors","authors":"Meera Day Towler, T. Allison, P. Krueger, Karl D. Wygant","doi":"10.1115/GT2018-77222","DOIUrl":"https://doi.org/10.1115/GT2018-77222","url":null,"abstract":"This investigation studies fast-response pressure measurements as an indicator of the onset of surge in a single-stage centrifugal compressor. The objective is to determine an online monitoring approach for surge control that does not rely on surge margin relative to maps from predictions or factory testing. Fast-response pressure transducers are installed in the suction piping, inducer, diffuser, and discharge piping. A speed line is mapped, and high-speed pressure data are collected across the compressor map. The compressor is driven into surge several times to collect pressure data between during surge and between surge events. Following testing, these data are post-processed via filtration and statistical analyses. It is determined that, when taken together, the mean and range of the standard deviation of the time signal for multiple time steps can be used to determine whether the compressor’s operating point is approaching surge for the conditions tested.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122591342","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}
G. Ceschini, L. Manservigi, G. Bechini, M. Venturini
Anomaly detection and classification is a key challenge for gas turbine monitoring and diagnostics. To this purpose, a comprehensive approach for Detection, Classification and Integrated Diagnostics of Gas Turbine Sensors (named DCIDS) was developed by the authors in previous papers. The methodology consists of an Anomaly Detection Algorithm (ADA) and an Anomaly Classification Algorithm (ACA). The ADA identifies anomalies according to three different levels of filtering. Anomalies are subsequently analyzed by the ACA to perform their classification, according to time correlation, magnitude and number of sensors in which an anomaly is contemporarily identified. The performance of the DCIDS approach is assessed in this paper based on a significant amount of field data taken on several Siemens gas turbines in operation. The field data refer to six different physical quantities, i.e. vibration, pressure, temperature, VGV position, lube oil tank level and rotational speed. The analyses carried out in this paper allow the detection and classification of the anomalies and provide some rules of thumb for field operation, with the final aim of identifying time occurrence and magnitude of faulty sensors and measurements.
{"title":"Detection and Classification of Sensor Anomalies in Gas Turbine Field Data","authors":"G. Ceschini, L. Manservigi, G. Bechini, M. Venturini","doi":"10.1115/GT2018-75007","DOIUrl":"https://doi.org/10.1115/GT2018-75007","url":null,"abstract":"Anomaly detection and classification is a key challenge for gas turbine monitoring and diagnostics. To this purpose, a comprehensive approach for Detection, Classification and Integrated Diagnostics of Gas Turbine Sensors (named DCIDS) was developed by the authors in previous papers. The methodology consists of an Anomaly Detection Algorithm (ADA) and an Anomaly Classification Algorithm (ACA). The ADA identifies anomalies according to three different levels of filtering. Anomalies are subsequently analyzed by the ACA to perform their classification, according to time correlation, magnitude and number of sensors in which an anomaly is contemporarily identified.\u0000 The performance of the DCIDS approach is assessed in this paper based on a significant amount of field data taken on several Siemens gas turbines in operation. The field data refer to six different physical quantities, i.e. vibration, pressure, temperature, VGV position, lube oil tank level and rotational speed. The analyses carried out in this paper allow the detection and classification of the anomalies and provide some rules of thumb for field operation, with the final aim of identifying time occurrence and magnitude of faulty sensors and measurements.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116510293","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 novel rotary liquid piston multi-phase pump that transfers pressure energy from high pressure motive fluid stream to a low pressure process fluid stream within a high speed multi-ducted rotor is presented. The multiple ducts in the rotor act like cylinders of a rotating liquid piston pump with the liquid-to-liquid interface between the working fluid and the motive fluid acting like a piston. This novel pump has promise to solve challenges typically seen in multi-phase pumping and in trans-critical and supercritical CO2 compression systems, na m el y, risks due to phase change, two-phase compression inefficiencies, rotordynamic instabilities and sealing challenges etc. In this design the entrance and exit flow angles impart momentum to the rotor and the rotor achieves a self-sustained rotation without external power. The rotational speed dictates the volumetric efficiency, travel distance of the liquid piston within the ducts and the zero-mixing effectiveness of the design. This creates a very efficient pumping/compression system with just one moving part and three stationary parts, which can handle very high pressures and temperatures typical of supercritical CO2 turbomachines and also mitigates some of the rotordynamic stability challenges typically seen in MW-scale sCO2 turbomachinery designs. Ability of the pressure exchanger to dynamically maintain micro-scale gaps between rotor and stators through intelligent pressure balancing features relaxes the need to have complex dynamic seals. In this paper, use of this novel pump for multi-phase CO2 pumping application is explored through an advanced 3D multi-scale multi-phase flow model. The model captures the phase transport, compressibility, advection & diffusion of one phase into the other using a hybrid Eulerian-Lagrangian algorithm. Using these advanced models, performance curves are developed and results for key performance parameters including phase mixing, compressibility losses, effect of inlet gas volume fractions etc. are presented. A detailed transient evolution of two-phase fluid piston interface in the rotor ducts that captures acoustic wave propagation and reflection is presented. This new technology has promise to solve challenges typically seen in multi-phase pumping/ compression, transcritical and supercritical CO2 compression systems or in applications where the traditional pumps face steep challenges like phase change, erosive/ corrosive fluids, particle laden flows with high particle loading or flows with high gas volume fractions. This technology renders itself useful to several applications including supercritical CO2 turbomachines, waste pressure recovery, applications in oil & gas extraction and carbon sequestration etc.
{"title":"A New Type of Rotary Liquid Piston Pump for Multi-Phase CO2 Compression","authors":"A. Thatte","doi":"10.1115/GT2018-77011","DOIUrl":"https://doi.org/10.1115/GT2018-77011","url":null,"abstract":"A novel rotary liquid piston multi-phase pump that transfers pressure energy from high pressure motive fluid stream to a low pressure process fluid stream within a high speed multi-ducted rotor is presented. The multiple ducts in the rotor act like cylinders of a rotating liquid piston pump with the liquid-to-liquid interface between the working fluid and the motive fluid acting like a piston. This novel pump has promise to solve challenges typically seen in multi-phase pumping and in trans-critical and supercritical CO2 compression systems, na m el y, risks due to phase change, two-phase compression inefficiencies, rotordynamic instabilities and sealing challenges etc. In this design the entrance and exit flow angles impart momentum to the rotor and the rotor achieves a self-sustained rotation without external power. The rotational speed dictates the volumetric efficiency, travel distance of the liquid piston within the ducts and the zero-mixing effectiveness of the design. This creates a very efficient pumping/compression system with just one moving part and three stationary parts, which can handle very high pressures and temperatures typical of supercritical CO2 turbomachines and also mitigates some of the rotordynamic stability challenges typically seen in MW-scale sCO2 turbomachinery designs. Ability of the pressure exchanger to dynamically maintain micro-scale gaps between rotor and stators through intelligent pressure balancing features relaxes the need to have complex dynamic seals. In this paper, use of this novel pump for multi-phase CO2 pumping application is explored through an advanced 3D multi-scale multi-phase flow model. The model captures the phase transport, compressibility, advection & diffusion of one phase into the other using a hybrid Eulerian-Lagrangian algorithm. Using these advanced models, performance curves are developed and results for key performance parameters including phase mixing, compressibility losses, effect of inlet gas volume fractions etc. are presented. A detailed transient evolution of two-phase fluid piston interface in the rotor ducts that captures acoustic wave propagation and reflection is presented. This new technology has promise to solve challenges typically seen in multi-phase pumping/ compression, transcritical and supercritical CO2 compression systems or in applications where the traditional pumps face steep challenges like phase change, erosive/ corrosive fluids, particle laden flows with high particle loading or flows with high gas volume fractions. This technology renders itself useful to several applications including supercritical CO2 turbomachines, waste pressure recovery, applications in oil & gas extraction and carbon sequestration etc.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116108018","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}
can ma, Zhiqiang Qiu, J. Gou, Jun Wu, Zhenxing Zhao, Wei Wang
The supercritical CO2-based power cycle is very promising for its potentially higher efficiency and compactness compared to steam-based power cycle. Turbine is the critical component in the supercritical CO2-based cycle which delivers the power. Compared to the gas turbine or steam turbine of similar power output, the size of the supercritical CO2 radial turbine is much smaller and the axial force on the impeller is much larger. The load on the thrust bearing could be too heavy for long-term safe operation. Therefore, it is necessary to balance the axial force on the impeller through aerodynamic design to reduce the load on the thrust bearing. The impeller backface design with radial pump-out vanes proves to be an effective design to reduce the axial force on the impeller of radial turbomachinery, which is widely used in the pump industry. This work investigates the impeller backface cavity flow of a supercritical CO2 radial turbine and the application of the pump-out vanes to the impeller through computational fluid dynamics simulations. Design variations of the pump-out vane are presented and their performance variations are discussed from the view of viscous compressible fluid, instead of the commonly assumed inviscid incompressible fluid in the pump industry.
{"title":"Axial Force Balance of Supercritical CO2 Radial Inflow Turbine Impeller Through Backface Cavity Design","authors":"can ma, Zhiqiang Qiu, J. Gou, Jun Wu, Zhenxing Zhao, Wei Wang","doi":"10.1115/GT2018-76019","DOIUrl":"https://doi.org/10.1115/GT2018-76019","url":null,"abstract":"The supercritical CO2-based power cycle is very promising for its potentially higher efficiency and compactness compared to steam-based power cycle. Turbine is the critical component in the supercritical CO2-based cycle which delivers the power. Compared to the gas turbine or steam turbine of similar power output, the size of the supercritical CO2 radial turbine is much smaller and the axial force on the impeller is much larger. The load on the thrust bearing could be too heavy for long-term safe operation. Therefore, it is necessary to balance the axial force on the impeller through aerodynamic design to reduce the load on the thrust bearing. The impeller backface design with radial pump-out vanes proves to be an effective design to reduce the axial force on the impeller of radial turbomachinery, which is widely used in the pump industry. This work investigates the impeller backface cavity flow of a supercritical CO2 radial turbine and the application of the pump-out vanes to the impeller through computational fluid dynamics simulations. Design variations of the pump-out vane are presented and their performance variations are discussed from the view of viscous compressible fluid, instead of the commonly assumed inviscid incompressible fluid in the pump industry.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124863964","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}
Supercritical carbon dioxide (sCO2) Brayton power cycles take advantage of the high density of CO2 near the critical point to reduce compressor power and increase cycle efficiency. However, thermophysical properties of CO2 vary drastically near the critical point. Concerns of large property variations and liquid formation within the compressor can result in sCO2 cycle designers selecting compressor inlet operating conditions substantially above the critical point, thereby reducing cycle performance. The Naval Nuclear Laboratory has built and tested the 100 kWe Integrated System Test (IST) to demonstrate the ability to operate and control an sCO2 Brayton power cycle over a wide range of conditions. Since the purpose of the IST is focused on controllability, the design compressor inlet conditions were selected to be 8.2°F (4.6°C) and 270 psi (18.4 bar) above the critical point to reduce the effect of small variations in compressor inlet temperature and pressure on density. This paper evaluates the effect of design compressor inlet pressure on cycle efficiency for a simple recuperated Brayton cycle and the performance of an operating Brayton power cycle with a fixed design over a range of compressor inlet pressures.
{"title":"Effect of Compressor Inlet Pressure on Cycle Performance for a Supercritical Carbon Dioxide Brayton Cycle","authors":"E. Clementoni, T. Cox","doi":"10.1115/GT2018-75182","DOIUrl":"https://doi.org/10.1115/GT2018-75182","url":null,"abstract":"Supercritical carbon dioxide (sCO2) Brayton power cycles take advantage of the high density of CO2 near the critical point to reduce compressor power and increase cycle efficiency. However, thermophysical properties of CO2 vary drastically near the critical point. Concerns of large property variations and liquid formation within the compressor can result in sCO2 cycle designers selecting compressor inlet operating conditions substantially above the critical point, thereby reducing cycle performance. The Naval Nuclear Laboratory has built and tested the 100 kWe Integrated System Test (IST) to demonstrate the ability to operate and control an sCO2 Brayton power cycle over a wide range of conditions. Since the purpose of the IST is focused on controllability, the design compressor inlet conditions were selected to be 8.2°F (4.6°C) and 270 psi (18.4 bar) above the critical point to reduce the effect of small variations in compressor inlet temperature and pressure on density. This paper evaluates the effect of design compressor inlet pressure on cycle efficiency for a simple recuperated Brayton cycle and the performance of an operating Brayton power cycle with a fixed design over a range of compressor inlet pressures.","PeriodicalId":412490,"journal":{"name":"Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy","volume":"102 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123864699","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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