Academic literature on the topic 'Suction water tanks'
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Journal articles on the topic "Suction water tanks"
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Dartnell, Lawrence. "The Thermal–Hydraulic Design of Main Feed Water Pump Suction Systems for Large Thermal Power Plant." Proceedings of the Institution of Mechanical Engineers, Part A: Power and Process Engineering 199, no. 4 (November 1985): 215–27. http://dx.doi.org/10.1243/pime_proc_1985_199_028_02.
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British domestic design practice is described for boiler feed pump suction systems associated with high level deaerator/feed water tanks in large modern power plant. The objective of thermal–hydraulic design is the provision of adequate pressure to boiler feed water pump suctions under all transient and steady state conditions to ensure continuity of water flow and reliable pump operation. Methods are available for the determination of pressure decay in feed tanks during load transients, but the successful application of mathematical relationships between pressure decay and pressure rise in suction pipework depends on the correct identification of operational circumstances. Progress in recent years has been on the identification of circumstances which produce governing conditions and has taken design practice beyond the stage established by early workers. Developed practice has been successfully applied by the Central Electricity Generating Board and its main plant contractors to forty-nine 500 MW units in coal- and oil-fired stations and to twenty-three 660 MW units in coal, oil and advanced gas-cooled reactor stations, which at 39 680 MW, constitutes the major proportion of plant in England and Wales. Aspects of plant behaviour and operation crucial to successful system design are featured. Recommendations are made for plant layout, pipework routing, tank outlet and pipework sizing, net positive suction head (NPSH) determination etc.
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Park, Kyu-Sik, Hung-Truyen Luong, and Joonmo Choung. "Numerical Study on the Tank Heel Determination Using Smoothed Particle Hydrodynamics." Journal of Marine Science and Engineering 9, no. 9 (September 17, 2021): 1016. http://dx.doi.org/10.3390/jmse9091016.
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Tank heel minimization is a significant issue in the design of LNG fuel tanks because it is associated with stable suction pump operation and thermal shock requirements during LNG bunkering. This study examined how the LNG tank heel is minimized, maintaining a suction pump fully submerged in LNG during dynamic vessel motion. The study assumed two LNG fuel tanks mounted on the forward deck of a 50,000 deadweight class oil product carrier. Information on the dimensions and shape of the LNG fuel tank was determined from Wartsila’s brochure, and the specifications of Vanzetti’s suction pump were referred to. The LNG fuel tank and LNG heel were modeled as rigid elements and hydrodynamically smoothed-particles, respectively. The number of particles could be determined by performing even keel analyzes by adding or subtracting particles until the target head was satisfied under the gravity load. To simulate the motion of the LNG fuel tank, the pitch and roll periods and amplitudes of the ship were calculated using the DNV classification rules. Visual observations of the dynamic flow during the pitch and roll motions with respect to the ship’s center of mass showed that the roll motion was more critical from the viewpoint of the LNG heel than the pitch motion. After performing the simulations for three cycles of roll and pitch motions, the suction pump submergence was reviewed in the last cycle. Under the conditions assumed in this study, a filling ratio of 15% was determined as the minimum LNG tank heel. Although the LNG heel has customarily been determined, the LNG heel needs to be determined through hydrodynamic analyses of each vessel because it depends on the shape of the fuel tank and the vessel motion characteristics.
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Huang, Shi Feng, Feng Wang, Hui Xu, and Xiao Xian Wei. "Research on Optimal Operation of Raw Water Pumping System Based on Hydromechanics in Waterworks." Applied Mechanics and Materials 327 (June 2013): 294–300. http://dx.doi.org/10.4028/www.scientific.net/amm.327.294.
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According to the raw water pumping system with constant speed pump and variable speed pumps based on hydromechanics in waterworks, the hydraulic simulation models were built including pump station, water tanks, suction well etc. Based on the analysis of objective function and constraints of water treatment structures and consideration of pump operation and initial water level of clean-water-tank, the compact optimal operation mathematical models were built. Finally, correctness and advantage of the mathematical models were proved by the optimal simulation of Jinshan water supply project, which provided the valuable reference for the energy-saving operation of raw water pumping system.
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Müller, Gerson A., Fernando T. Name, Frederico C. L. Pacheco, and Carlos B. Marcondes. "Analysis of an alternative method for the study of bromeliad-associated fauna in plants with different foliar organization." Anais da Academia Brasileira de Ciências 82, no. 4 (December 2010): 903–6. http://dx.doi.org/10.1590/s0001-37652010000400012.
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The efficiency of an alternative method of collection (by suction of water) for the study of Culicidae and Chironomidae (Diptera), Scirtidae (Coleoptera) and Coenagrionidae (Odonata) in bromeliads with different foliar architecture in a restinga at Florianópolis, SC, Brazil, was studied. The alternative method was less efficient to collect Culicidae and Chironomidae (Wilcoxon test p < 0.05) and was more efficient to Scirtidae and Coenagrionidae (Wilcoxon test p > 0.05) from Aechmea lindenii. This method was less efficient to collect insects of all groups from Vriesea friburgensis (Wilcoxon test p < 0.05). The alternative method was efficient to estimate the diversity of these insects in both species of bromeliads. The higher mobility of immature forms of beetles and dragonflies, and the availability of only one tank in Aechea lindenii, contrasting to several tanks in Vriesea friburgensis that help the suction of these immature, probably influenced the results, which indicated that the suction method should not replace the dismantling in the study of Culicidae and Chironomidae. This method can be useful to get immature forms of Scirtidae and Coenagrionidae in one-tank bromeliads.
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Han, M. Y., and J. S. Mun. "Particle behaviour consideration to maximize the settling capacity of rainwater storage tanks." Water Science and Technology 56, no. 11 (December 1, 2007): 73–79. http://dx.doi.org/10.2166/wst.2007.778.
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Design of a rainwater storage tank is mostly based on the mass balance of rainwater with respect to the tank, considering aspects such as rainfall runoff, water usage and overflow. So far, however, little information is available on the quality aspects of the stored rainwater, such as the behavior of particles, the effect of retention time of the water in the tank and possible influences of system configuration on water quality in the storage tank. In this study, we showed that the performance of rainwater storage tanks could be maximized by recognizing the importance of water quality improvement by sedimentation and the importance of the system configuration within the tank, as well as the efficient collection of runoff. The efficiency of removal of the particles was increased by there being a considerable distance between the inlet and the outlet in the rainwater storage tank. Furthermore, it is recommended that the effective water depth in a rainwater tank be designed to be more than 3 m and that the rainwater be drawn from as close to the water surface as possible by using a floating suction device. An operation method that increases the retention time by stopping rainwater supply when the turbidity of rainwater runoff is high will ensure low turbidity in the rainwater collected from the tank.
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Lin, Wei Ting, Meng Hsiu Hsieh, Yuan Chieh Wu, and Chin Cheng Huang. "Response Spectrum Analysis of the Condensate Storage Tank in a Nuclear Power Plant." Applied Mechanics and Materials 284-287 (January 2013): 1421–25. http://dx.doi.org/10.4028/www.scientific.net/amm.284-287.1421.
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Following the nuclear power plant accident in Fukushima Japan, seismic capacity evaluation has become a crucial issue in combination building safety. Condensate storage tanks are designed to supplies water to the condensate transfer pumps, the control rod drive hydraulic system pumps, and the condenser makeup. A separate connection to the condensate storage tank is used to supply water for the high pressure coolant injection system, reactor core isolation cooling system, and core spray system pumps. A condensate storage tank is defined as a seismic class I structure, playing the important role of providing flow to the operational system and the required static head for the suction of the condensate transfer pumps and the normal supply pump. According to the latest nuclear safety requirements, soil structure interaction must be considered in all seismic analyses. This study aims to rebuild the computer model of condensate storage tanks in Taiwan using the SAP 2000 program in conjunction with the lumped mass stick model and to evaluate the soil structure interaction by employing the SASSI 2000 program. The differences between the results with the soil structure interaction and spring model are compared via natural frequency and response spectrum curves. This computer model enables engineers to rapidly evaluate the safety margin of condensate storage tank following the occurrence of earthquakes or tsunamis.
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Abdalla, Abdulmenam A., Ali K. Muftah, and Ahmed O. Amhamed. "THEORETICAL ANALYSIS AND GRAPHICAL REPRESENTATION OF THE SYSTEM CURVE FOR WATER PIPELINE CONNECTING ZAWIA DESALINATION PLANT WITH HARSHA TANKS." Scientific Journal of Applied Sciences of Sabratha University 2, no. 1 (April 25, 2019): 38–51. http://dx.doi.org/10.47891/sabujas.v2i1.38-51.
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The flow of water within a pipeline system causes loss of energy due to friction effects. To overcome these losses, energy is added to the water through the pump. So, the right pump selection is important for providing the required flow rate. The first step to select a right pump for any pipeline system is calculating the performance curve of piping system, which is a graphical representation of the energy required to move a given flow rate through a piping system and is used to identify the characteristics of the system's pump. For this purpose, the system curve for the water pipeline connecting the main reservoirs of Zawia desalination plant to the sub-tanks in Harsha has been evaluated and represented graphically in H-Q curve of the selected pump. This water pipeline network consists of sets of pipes connected in parallel and series with a total length of 5 km. The system NPSHA at different water levels in the suction tank at the maximum system flow rate of 800 (m3/hr) has been calculated to ensure avoiding cavitations problem in the selected pump.
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Stanley, C. D., G. A. Clark, E. E. Albregts, and F. S. Zazueta. "USE OF FIELD-LOCATED DRAINAGE LYSIMETERS FOR THE DETERMINATION OF STRAWBERRY WATER REQUIREMENTS." HortScience 25, no. 9 (September 1990): 1097d—1097. http://dx.doi.org/10.21273/hortsci.25.9.1097d.
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Sixteen field-located drainage lysimeters (each 60 cm wide, 2.44 m long, 60 cm deep) designed specifically for determination of water requirements for fruiting strawberry production (season - Oct to April) were installed in 1986. Each lysimeter was equipped with individual micro-irrigation and drainage collection systems automated for minimal management input. Initially, computer control (using a low-cost microcomputer) was used to continuously check switching-tensiometers located in each lysimeter and apply irrigation water as needed, A drainage suction (-10 MPa) was applied continuously to simulate field drainage conditions. Manually-installed lysimeter covers were used to protect the plots from interference from rainfall when needed, Initial irrigation application treatments were set at four levels of soil moisture tension controlled by tensiometers and were measured using flow meters for each lysimeter. This paper will discuss problems that were experienced with the initial setup (difficulty in measuring actual application amounts, tensiometer and computer control, elimination of rainfall interference, uniformity of irrigation application, and salinity in the rooting zone) and the modifications (pressurized reservoir tanks, construction of motorized rain-out shelter, micro-irrigation emitters used, and fertilization program) which have been made to overcome them,
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Kim, Tae Ho, Kyong Uk Yang, Duck Jong Jang, and David W. Fredriksson. "The Submerging Characteristics of a Submersible Fish Cage System Operated by Compressed Air." Marine Technology Society Journal 44, no. 1 (January 1, 2010): 57–68. http://dx.doi.org/10.4031/mtsj.44.1.1.
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AbstractA numerical technique is developed to evaluate the submerging characteristics of a full-scale fish cage system operated by compressed air. The results of the numerical model are then compared to both physical model tests and in situ measurements. The cages incorporate the use of ballast tanks for fixed buoyancy and variable buoyancy control. The system is raised by injecting air from a compressor into the variable buoyancy ballast tanks. It is then lowered by releasing the air. The surfacing and submerging characteristics of the fish cage calculated with the numerical technique were similar to measurements obtained with the physical model and in situ tests. It was also found that the quantity of the inflow water is influenced more by the diameter of the suction pipe rather than by the changes in the pressure of compressed air. In addition, the changes in the diameter of the air evacuation pipe are considered to have a greater impact during the ascent rather than descent of the system. Other major factors that affect the vertical movement of the fish cage system operated by compressed air are the seawater flow rates and air flow rate supplied to the variable ballast system. It was concluded that the numerical method could be useful in analyzing various parameters required to optimize the surfacing and submerging characteristics of a fish cage system operated by compressed air.
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Nagaoka, H., S. Ueda, and A. Miya. "Influence of bacterial extracellular polymers on the membrane separation activated sludge process." Water Science and Technology 34, no. 9 (November 1, 1996): 165–72. http://dx.doi.org/10.2166/wst.1996.0203.
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The objective of this study is to elucidate influence of bacterial extracellular polymers (EPS) on the performance of the submerged membrane separation activated sludge process (SMAS). Hollow fiber membrane modules were submerged in laboratory-scale reactors and the permeate was pulled out from the modules by suction pumps. Acetic acid was used as a carbon source and peptone or ammonium nitrogen was used as a nitrogen source in the substrate. The change of EPS amount both in the mixed liquor and on the membrane was measured and its influence on the permeability of the membrane was studied. EPS was accumulated in the aeration tanks and also on the membrane, which caused an increase of viscosity of the mixed liquor and an increase in the filtration resistance. Specific resistance of EPS was calculated to be of the order of 1016 to 1017 m kg−1. Change of the filtration resistance was explained as a function of viscosity of the mixed liquor, which is caused by rapid attachment of the suspended EPS and rapid detachment of the attached EPS. Detachment rate of the attached EPS was calculated to be nearly constant during the operation.
Dissertations / Theses on the topic "Suction water tanks"
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Král, Tomáš. "Optimalizace vytápění nadzemních požárních nádrží." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2016. http://www.nusl.cz/ntk/nusl-240033.
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This thesis describes analysis and optimization of existing heating system aboveground fire sprinkler water tanks. The purpose is to design a heating system so as to achieve optimal operating and economic conditions for the operation of heating in winter. I will use available computer software and adhere to the applicable regulations and standards. Using experi-mental methods and computer simulations I will assess the current state of the heating system which in turn will provide an optimizing its use and operation.
Book chapters on the topic "Suction water tanks"
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"Rotenone in Fisheries: Are the Rewards Worth the Risks?" In Rotenone in Fisheries: Are the Rewards Worth the Risks?, edited by Charles W. Thompson, Craig L. Clyde, Douglas K. Sakaguchi, and Leo D. Lentsch. American Fisheries Society, 2001. http://dx.doi.org/10.47886/9781888569339.ch10.
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<em>Abstract.—</em>-An aspirator, was developed by the Utah Division of Wildlife Resources to mix rotenone slurry used to eradicate undesirable fish species from Strawberry Reservoir, Utah, in 1990. An aspirator was the best method that Utah has developed for mixing powdered rotenone into a slurry. Slurry characteristics were as good or better than those achieved by any other mixing technique tried. The system utilized a high pressure pump that forced water through the aspirator creating suction used to vacuum powdered rotenone from bulk bags (1,000 lb capacity). The powder and water combined inside the aspirator chamber forming a slurry. The slurry was discharged directly on to the reservoir surface or delivered into barge tanks from the aspirator nozzle. Rotenone loss in the form of dust was significantly reduced compared to other mixing techniques and there was limited exposure of the chemical to personnel. One person could operate the aspirator efficiently.
Conference papers on the topic "Suction water tanks"
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Johansson, Andrew, Mahadevan Padmanabhan, Stuart Cain, Bryan Meyer, and David Schowalter. "Hydraulic Modeling of Air-Entraining Vortex Formation During Flow Withdrawal From Water Storage Tanks." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75169.
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In response to recent U.S. Nuclear Regulatory Commission (NRC) Component Design Bases Inspection (CBDI) issues, many US nuclear power stations have been required to demonstrate that minimum submergence requirements were properly determined for flow withdrawal from various safety related storage tanks. In many cases, the licensees failed to consider a vortex allowance, or applied an inappropriate vortex methodology. For Duke Energy’s McGuire Station, a Refueling Water Storage Tank (RWST) model was constructed using a geometric scale of 1:4.073. Testing included transient water level conditions simulating the field for selected flows (corresponding to prototype flows of 1,600 to 19,700 gpm) and water levels giving submergences of 1 to 5 ft above the suction nozzle in the model (prototype submergences of 4 to 20.3 ft). Results showed that with no return flow, the submergence at the onset of air entrainment ranged from 0.049 to 0.705 ft prototype for flows ranging from 1,600 to 19,700 gpm prototype, respectively. Based on the test results, it was determined that a vortex suppression device was not required for the McGuire RWST, as the expected water levels during operation would be higher than those indicated for onset of air entrainment for a given flow. The scale model testing showed that the critical submergences for initiation of air-entraining vortices were much lower than those predicted by Hydraulic Institute guidelines.
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Humphrey Facendola, Amie, Ludwig Haber, and Andrew Johansson. "Vortexing and Air Withdrawal Evaluations for Storage Tanks Using Physical Hydraulic Model Studies." In 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60768.
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Knowing and minimizing the critical submergence of storage tanks for various operating conditions in power plants is very valuable to engineers. The goal is to maximize the usable emergency water volume and maintain tank operations such that no air (from vortexing or otherwise) is ever withdrawn into tank suction nozzle(s), that then could jeopardize continued operation of system pumps. While empirically derived curves for air withdrawal predictions can provide some general guidance, they cannot predict actual submergence requirements, especially when return flow is present and water level drops continuously. Physical hydraulic models can be used effectively to determine the critical submergence for plant specific geometries at all possible operating conditions. This paper presents a range of results of physical model studies conducted to determine critical submergence at various operating conditions and compares them with empirically derived curves to determine any possible trends or definitive rules. Critical submergence for all points on all studies was below the Hydraulic Institute boundary curve for pump intake design and below the Reddy and Pickford boundary curve for all cases without return flow to the tank and most with return flow to the tank. Both are much more conservative estimates at high Froude numbers as compared with lower Froude numbers. The Harleman curve, which was derived for the selective withdrawal of density stratified fluids, is neither predictive nor conservative.
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Hoznedl, Michal, Ladislav Tajč, Lukáš Bednář, Aleš Macálka, and Antonín Živný. "Separation of Water Film From Last Stage Guide Blades of 1000 MW Steam Turbine." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90221.
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Abstract The paper deals with experimental research of water and steam flow through the grooves in hollow stator blades of the steam turbine last stages with the support of CFD calculations. Also the amount of water sucked by the circumferential groove in the upper limiting wall between the last stage rotor and stator blade was experimentally measured. Measuring took place on a steam turbine with nominal output 1000 MW. With gradual increase of the turbine output it was possible to measure parameters of hollow blades suction for outputs 205, 460, 730, 870 and also 1006 MW. Before starting turbine a complex measuring system was installed consisting of cyclone separator, set of measuring tanks, orifice and pressure sensors and transducers. This measuring system was connected to one hollow stator blade near the horizontal joint. After the measurement the extraction of steam water mixture from this blade was transferred to the condenser via the diffuser chamber in the same way as other non-measured blades. Based on measured data, i.e. the pressure in the hollow stator blade and the flow rate of water captured by the hollow stator blade, it is possible to define the efficiency of suction tract from the viewpoint of total wetness in the inter-stage channel and from the viewpoint of rough liquid phase. The rough liquid phase means water films that flow near the draining grooves and sucked inside to the grooves. The main part of the submitted paper is an analysis of the measured data. Among the analysis results are, besides the flows of rough water phase along the blade surface, the above mentioned efficiency of total wetness suction and of water film suction. For the needs of the analysis there are certain input data, e.g. the value of static pressure and wetness on the blade surface close to the slots that must be defined theoretically using flow path calculations or using CFD methods. In this case, in order to obtain input data, CFD simulations were used when the whole last stage was calculated with the diffuser and exhaust hood. Boundary conditions for CFD were taken from experimental measurements that took place simultaneously with measurement of separated water phase. Numerical simulations were not running for all outputs, but only for three of them — 460, 730 and 1006 MW. For this reason there are no sufficient data for CFD calculations for all outputs and input data of other cases had to be extracted and, based on experience, extrapolated. On the circumferential groove only a part of 30 mm of length was measured, again near the horizontal joint. Due to a short measured groove length it was not possible to obtain the water flow data which would describe suction properties for the whole circumference. The results of experimental measurements provide very important information about the whole suction tract behaviour and its ability to remove liquid water films from the stator blades surface. As very good qualities of the suction tract were confirmed by the measurement, it could be stated that hollow stator blades combined with the circumferential groove on the upper limiting wall is still a suitable technical solution for lowering erosion loading of the last stages. When using a properly dimensioned and correctly working suction system, erosion loading of LSB leading edges on the tip can be lowered by almost a half.
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Ezekoye, L. Ike, Ryan D. Griffin, William M. Turkowski, and Gregory R. Williams. "An Integrated Approach for Monitoring Gas Accumulation in Safety Related Systems." In ASME 2009 Pressure Vessels and Piping Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/pvp2009-77957.
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Gas intrusion into safety related systems, such as the Emergency Core Cooling System (ECCS), Decay Heat Removal (DHR) and Containment Spray (CS) system in nuclear power plants is undesirable and has led to pump binding and damaging water hammer events. Furthermore, total or momentary loss of hydraulic performance in safety related pumps has occurred, which has led to pump damage rendering the pumps unable to perform their safety functions or reduce the pump discharge pressure and flow capacity to the point that the system cannot perform its design function. Extreme cases of water hammer can result in physical damage to system piping, components and supports, and possible relief valve lifting events with consequential loss of inventory. The U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter GL-2008-01, “Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,” requiring U.S. utilities to demonstrate that suitable design, operation and testing measures are in place to maintain licensing commitments. GL-2008-01 outlines a number of actions that are detailed in nature, such as establishing pump void tolerance limits, establishing limits on pump suction void fractions, assuring adequate system venting capability, identifying all possible sources of gas intrusion, preventing vortex formation in tanks and determining acceptable limits of gas in system discharge piping. Regarding one of these issues, GL-2008-01 indicates that the amount of gas that can be ingested without significant impact on pump operability and reliability is not well established and is known to depend on pump design, gas dispersion and flow rate. Each U.S. nuclear power plant licensee is required to evaluate their ECCS, DHR and CS system design, operation and test procedures to assure that gas intrusion is minimized and monitored in order to maintain system operability and compliance with the requirements of the U.S. code of federal regulations 10 CFR 50 Appendix B. Typically, gases get into the safety related systems through a number of mechanisms, such as maintenance, gas desorption, vortex activities, cavitation, etc. This paper discusses the sources of gas into safety related systems and the challenges associated with management of gas voids in these systems. A number of technologies exist that can detect the gas that accumulates in the safety related piping. These technologies are discussed and an integrated approach for monitoring gas accumulation in safety related pipes is presented. Issues such as methods to get rid of gases and venting periodicity are discussed. Industry efforts to address the management of gases in these systems are also presented.
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Hesar, Majid, and Raquel Maciel. "Geotechnical Design of Vertically Loaded Hybrid Suction-Gravity Anchors." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61503.
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The Sapinhoá and Lula North-East fields, 300km offshore Rio de Janeiro, Brazil are the two pilot fields of the Pre-salt development strategy. Field architecture consists of satellite wells connected to a spread moored FPSO in each of the fields. Through a design competition Petrobras and Partners selected the de-coupled riser system developed by Subsea 7. In each field two BSRs (Buoy Supporting Risers) anchored at 250m below waterline support the rigid risers on one side and flexible flowlines running to the FPSO on the other. Each BSR displaces close to 10,000t of water and provides a nominal net up thrust of 3,250t. This Paper highlights the engineering challenges and the solution developed for the large-scale foundation anchors that support these massive BSRs in the harsh environment of the Santos Basin in 2140m water depth. Vertically below each corner of the BSR tank an 8m diameter by 18m penetration suction anchor houses the receptacles for the pair of tethers. Tension in the tethers was tuned to optimise the system stiffness (to minimise lateral BSR excursion orbits and avoid clash of risers and FPSO mooring lines) while requiring minimum anchor capacity. Four ballast modules of 150t each sit on top of each suction anchor to provide the remainder of the required uplift resistance. Soil conditions across both fields consist of soft silty clay. A geotechnical FE model of the suction anchor in Abaqus was used to evaluate the interaction of the structure, surrounding soil and trapped water beneath the top cap. The model was used to develop the complete load-displacement curves of the system during the undrained design current events. A consolidation FE model using the Soft Soil model in PLAXIS showed that the hybrid anchor/ballast system under sustained uplift loading is stable throughout the design life for the level of sustained design load. Although the LRFD verification format of suction anchors and gravity anchors are well covered in the design codes, there seems to be a gap in the coverage of this particular type of hybrid anchor. The governing condition was found to be the long term drained pull-out capacity under sustained loading with the assumption of slowly leaking suction port and air evacuation port at the top.
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Roe, T. F., G. Macfarlane, and Y. Drobyshevski. "Heave Added Mass and Damping of a Suction Can in Proximity to the Sea Floor." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57559.
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Suction cans are usually deployed by the crane of a construction vessel, which must have adequate capacity to withstand the dynamic hook loads generated by motions of the vessel and heave response of the suction can. Before the structure is placed on the sea floor, it must be positioned above the target location; in this phase the suction can is manoeuvred into position being suspended in proximity to the sea floor. Hydrodynamic properties of the structure in the positioning phase are different from those experienced during the decent, due to the effect of the bottom proximity. As a result, the dynamic hook loads experienced in this phase may be also different from the deep water condition. The objective of this study is to quantify these effects; in particular the impact of the bottom proximity on the heave added mass and hydrodynamic damping. The added mass and damping of a 6-metre diameter suction can, of dimensions typical for Australian North West Shelf conditions, have been determined by testing a 1:10 model in the 4.2 m deep water tank of the Australian Maritime College. Free decay tests were conducted at several heave frequencies, and the heave added mass and damping determined. Four clearances of the model from the sea floor were investigated ranging from 1.20 to 0.20 of the can height. For each clearance, several sizes of open hatches were examined, by testing the model with 3 pairs of hatches of various diameters, with up to 4.8% of the relative area open. Model tests demonstrate that the heave added mass and damping increase as the suction can approaches the sea floor. Increase in added mass is found to be within 20% of its deep water value, and is made less pronounced by opening hatches of larger area. Linear (proportional to velocity) hydrodynamic damping also increases moderately as the under-bottom clearance reduces. Quadratic (proportional to velocity squared) damping is strongly affected, especially at very small clearances, with drag coefficient reaching unusually high values; this is attributed to substantial constraining effect of the bottom, which causes increasing flow velocities past the lower edge of the can. Results of the tests are presented, and their application for the installation lift analysis is discussed.
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Tanaka, Teiichi. "Thermodynamic Effect and Cavitation Performance of a Cavitating Centrifugal Pump." In ASME-JSME-KSME 2011 Joint Fluids Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajk2011-06025.
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The thermodynamic effect which affects the cavitation performance of a cavitating centrifugal pump was investigated experimentally using liquid nitrogen. To measure the pump cavitation performance, a test setup which could carry out experiments using both liquid nitrogen and cold water was constructed. The test setup consisted of a suction tank, a test pump, a mass flow meter, a ball valve and pipes. Vacuum-insulated pipes were used. The test pump was a centrifugal type magnetic pump, and two impellers, which differed in cavitation performance, were used in experiments. Cavitation performance using liquid nitrogen or cold water could be obtained from the measurement of the pump suction and delivery pressure, the pump suction and delivery temperature, and the discharge flow rate. And an improvement in pump cavitation performance could be seen when comparing the experimental results from using liquid nitrogen with those from using cold water. The experimental results indicated that cavitation performance using liquid nitrogen was better than that using cold water. This improvement in cavitation performance was thought to be due to the thermodynamic effect of cavitation. And the estimated temperature depression due to the thermodynamic effect decreased with a decreasing flow coefficient. Moreover, it was shown that the estimated temperature depression due to the thermodynamic effect on the low cavitation performance impeller was larger than that on the high cavitation performance impeller at the same flow coefficient.
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Kakasoltani, Siamak, Mostafa Zeinoddini, Mahmoud R. Abdi, and Seyyed Abbas Mousavi Behnam. "On Penetration of Upright and Tapered Suction Caissons in Sand: An Experimental Study." In ASME 2010 29th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/omae2010-20499.
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Over the past two decades, suction caissons have been increasingly utilized as deep water anchors for floating structures, foundations of offshore wind turbines and even for jacket platforms. They penetrate into the sea bed by a combination of their buoyant weight and under base suction. Suction caissons have appeared as an efficient and economic alternative for foundations in the offshore industry. This concept, however, is relatively new, so the knowledge about their behavior has not yet gone far deep as that for other offshore foundation solutions such as driven pile systems. This paper reports some results from an experimental investigation into the installation of upright and tapered suction caissons. The 1g experiments have been carried out on eight small scale suction caissons. The aspect ratios, (the caisson length/its diameter) have been 1, 2, 3 and 4. The diameter has been constant and equal to 80 mm. Four specimens have had upright walls while the other four had a positive wall slope of 10%. The caissons have been installed in a soil tank containing very fine saturated silty sand. The penetration has been achieved under forced driving using a constant penetration rate. The effects of geometrical parameters and the soil density on the overall penetration force have been studied. it has been observed that, with both the upright and tapered caissons, the required force for full penetration increases by an increase in the aspect ratio. The penetration force required for full penetration of tapered models, has been two to three times higher than an equivalent upright caisson. With tapered caissons, the penetration forces have been found to be more sensitive to the soil density as compared to that with upright caissons. The experimental results for upright suction caissons have also been compared with a closed form analytical solution proposed by other researchers.
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Morgan, James W., and Timothy Gode. "BWR Recirculation Pump Adjustable Speed Drive Performance and Control Affects." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29733.
Full textAbstract:
Exelon Nuclear has recently installed adjustable speed drives (ASD), or variable frequency drives (VFD), in place of the original motor-generator (MG) sets for their boiling water reactor (BWR) recirculation pumps at Quad Cities. This paper reviews expected versus actual performance of the drives and motors. The discussion focuses on energy savings, motor starting characteristics, control accuracy and stability, motor and cable thermal behavior; as well as, a comparison of actual supply system input harmonic measurements versus analysis results. Included in the review are a few operational lessons learned with regard to the startup process, input medium voltage low speed holds, loss of cooling water pump suction pressure, cooling system surge tank level indication, and other miscellaneous points of interest.
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McAuliffe, B. R., and M. I. Yaras. "Separation-Bubble-Transition Measurements on a Low-Re Airfoil Using Particle Image Velocimetry." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68663.
Full textAbstract:
This paper presents experimental results on separation-bubble transition at low Reynolds number and low freestream turbulence, measured on an airfoil using particle image velocimetry (PIV). The two-dimensional PIV measurements have been performed over the suction surface of a low-Reynolds-number airfoil in a water tow-tank facility. Reynolds numbers, based on airfoil chord length and towing speed, of 40,000 and 65,000 have been examined at various angles of incidence, providing a range of streamwise pressure distributions and transitional separation-bubble geometries. The types of bubbles observed range from a short and thick bubble with separation near the leading edge of the airfoil, to a long and thin bubble with separation far downstream of the suction peak. The PIV measurements facilitate visualization of the vortex dynamics associated with separation-bubble transition. The growth of instability waves within the separated shear layer and eventual breakdown into turbulence is documented through the instantaneous vector fields. For all cases examined, large-scale vortex shedding and multiple reverse-flow zones are observed in the reattachment region. A technique for estimating the location of transition onset based on statistical turbulence quantities is presented, and comparisons are made to existing transition models.