bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Design of an Infrared Non-Imaging Device for a Full-Spectrum Solar Energy System
Authors: Dye Dan , Wood Byard , Fraas Lewis , Muhs Jeff
Published: January 2009

A solar collector/receiver system for a full-spectrum solar energy system is being designed by a research team lead by Oak Ridge National Laboratory and the University of Nevada, Reno. [1,2] This solar energy system is unique in that it utilizes the majority of the solar spectrum by splitting the infrared (IR) and visible energy for two different end uses. The visible light will be used for day lighting and the IR energy for electrical power generation. This paper is concerned with the optics that will provide uniform irradiance of the IR energy on the thermal photovoltaic (TPV) array. The benchmark full-spectrum collector/receiver and prototype TPV array have been built [3], so the work performed here is to match the two systems together for optimal performance. The design consists of a non-imaging (NI) system for the IR flux incident on the TPV array mounted behind the secondary mirror. Results of the ray-tracing analysis of the different systems tested are presented.
Measured Performance of a 35 Kilowatt Roof Top Photovoltaic System
Authors: Fanney A. Hunter , Weise Eric R. , Henderson Kenneth R.
Published: January 2009

A 35 kW roof top photovoltaic (PV) system has been installed at the National Institute of Standards and Technology (NIST) in Gaithersburg, Maryland. The system, located on the flat roof that connects NIST’s Administration Building to its adjoining conference and cafeteria facilities, produced NIST’s first site-generated renewable energy on September 14, 2001. In addition to providing electrical energy and reducing monthly peak electrical loads, the rear surface of each module is laminated to 51 mm of extruded polystyrene enhancing the thermal performance of the roof. A unique ballast system secures the photovoltaic system, eliminating the need for roof penetrations. An instrumentation and data acquisition package was installed to record the ambient temperature, wind speed, solar radiation, and the electrical energy delivered to the grid. Additional solar radiation instruments were installed after determining that the original solar radiation sensor was influenced by reflections from the south-facing wall of the Administration Building’s tower. NIST’s electric utility billing schedule includes energy and peak demand charges. The generation charges vary significantly depending upon the time interval — off-peak, intermediate, and on-peak — during which the energy is consumed. The schedule is divided into summer billing months (June-October) and winter billing months (November-May). During the winter billing months, the distribution, transmission, and generation peak demand charges are based on the greatest power demand imposed by the site on the grid. During the summer billing months an additional demand charge is imposed to capture electrical demand during the onpeak time interval. This paper summarizes the monthly and annual measured performance of the photovoltaic system. The monthly energy produced by the system is tabulated. Conversion efficiencies — computed using solar radiation measurements from a single photovoltaic cell radiation sensor, four thermopile-based radiation sensors located around the perimeter of the photovoltaic array, and a remotely located thermopile-based radiation sensor, are presented. Using the electric utility’s rate schedule, the monetary savings credited to the photovoltaic system is determined by combining the cost of the displaced energy with the reduction in peak demand charges attributable to the photovoltaic system. Finally, using utility provided data and the Environmental Protection Agency’s (EPA) Environmental Benefits Calculator, estimates are made of the avoided emissions of the photovoltaic system over its projected life span.
Identification of Barriers to PV Application Into the Building Design
Authors: Sozer Hatice , Elnimeiri Mahjoub
Published: January 2009

Even though there are a number of examples of BIPV, the concept of integration into the building and its design process have not yet been clearly defined. Lack of integration makes this new technology application expensive and very complex to implement. The challenge is how to make this new concept easily applicable and to spread this promising technology for users. In order for PV technology to be added effectively into the design process, full integration is essential. Full integration can be achieved when close interface develops between the PV System and the elements of the building design process. The design process is the spine that links the building from its inception all through its life cycle. The architects, along with the consultants and technical experts, are directly responsible for this process. PV has to be part of the building material and its building material properties have to be equivalent to other conventional building materials. PV has to fit into the building design process from the beginning. As a building component, it has to have certain standards and codes that will fit well within general building codes. This paper starts with the definition of the architectural building design process. It then continues with identifying the barriers that have direct effect on this process. These barriers are lack of interface (integration with typical building process), lack of common language, mismatched potential, unknown performance, and lack of economic analysis. The paper concludes by giving suggestions on how these barriers can be broken.
Study of a Solar Booster Assisted Ejector Refrigeration System With R134a
Authors: Herna´ndez Jorge I. , Estrada Claudio A. , Best Roberto , Dorantes Rube´n J.
Published: January 2009

A parametric study for a booster assisted ejector refrigeration system in steady state is carried out employing Lu’s ejector model in transition regime. The range of generator and condenser temperatures is considered for a solar powered system. Conceiving the ejector geometry, through the area ratio φ and the main throat area A*, and the system behavior, through the energy efficiency COPs, the exergy efficiency εs and energy ratio Er, it was found that their extreme values, lowest for A* and highest for the remainder, are reached at the highest generator temperature, TGE, and booster discharge pressure, pDIS, with the lowest condenser temperature, TCO, for the considered evaporator temperature, TEV, of −10°C. In regard to the ejector behavior, its maximum efficiency value, ηEJ, is reached for the highest TGE and the lowest TCO for an intermediate pDIS. If TCO is increased, the maximum ηEJ value is achieved at a higher pDIS. In spite of that the maximum ηEJ value is not reached at the highest pDIS, its influence is not reflected in system behavior because U always increases and its maximum value agrees with theory. The most important system and ejector parameters are presented as a reference.
Pinellas County Resource Recovery Facility Capital Replacement Project
Authors: Castro Donald J. , Stasis R. Peter
Published: January 2009

Pinellas County has completed the first two phases of a four-phase project intended to preserve the life of the Pinellas County Resource Recovery Facility (PCRRF) for years to come. This project, called the Capital Replacement Project (CRP), is designed to restore key portions of the County’s investment, and prepare the facility for a smooth transition to a new operating contract when the current term expires in 2007. By the end of 2004, with the scheduled completion of the CRP project, key plant systems and components are expected to be in robust condition and capable of many years of additional service.
Boiler Rebuild and Upgraded Design for Pinellas County MSW
Authors: Janik Carl , Cole Art
Published: January 2009

This paper discusses the Boiler Rebuild and Upgraded design features of the Pinellas County Solid Waste Recovery Plant located in Pinellas County, Florida. The Pinellas County Solid Waste Recovery plant consists of three 1000 Tons/Day Bulk Refuse fired boilers each designed to generate a nominal 250,000 lbs. of steam per hour (pph), at 750° F/615 psig. The boilers have been in operation since the early 1980’s and had come to the end of their reliability life. Based on the previous years of operating experience, specific areas of improvement were established. Desired improvements included; reduce tube bundle fouling, increase the length of time between the off-line cleaning cycles, reduce economizer exit gas temperature and increase steam capacity while achieving unit design steam conditions. Design options were evaluated using a computerized heat transfer mathematical model calibrated to the current level of boiler performance. The model enabled design modifications to be evaluated and optimized with respect to performance, maintenance and cost. Considering both the performance and maintainability allowed the design team to make a final evaluation and design selection that provided the greatest value over a long-term period. The unit was designed, fabricated and erected within an 18-month schedule. Performance and optimization testing was accomplished 8 weeks after start-up. The unit has met all of its performance guarantees and is fully operational.
Saving Energy With Brick, Refractory, Insulation and Lagging
Authors: Bases Gary J.
Published: January 2009

For the refuse-to-energy industry, “Saving Energy with Brick, Refractory, Insulation and Lagging (BRIL)” is as simply as understanding it’s refuse boiler. A refuse-fired boiler has many components to make it do what it is supposed to do. BRIL is a key component of the boiler just as important as the tubes that carry the water &/or steam, the soot blowers that keep the unit free of fly ash or dust, the burners that burn the fuel efficiently, the economizers that recover heat and pre-heat the water, and many more such systems found on, in and around the boiler. They all help keep the boiler operating thermally and energy efficient. Proper BRIL material selection and installation can have an energy savings of 5–7% per year in fuel consumption. That is why experts say, “brick, refractory, insulation, and lagging (BRIL) installed to save energy, saves money at a rate that is essential for efficient plant operation.”
Dealing With Residual Wastes at the Lancaster County Resource Recovery Facility
Authors: Forster Gary A.
Published: January 2009

The Lancaster County Resource Recovery Facility (RRF) is a 1,200 ton per day mass burn waste-to-energy plant that has been in operation since 1991. The plant is owned by the Lancaster County Solid Waste Management Authority (LCSWMA), but is operated for the Authority by Covanta Lancaster. During the initial years of operation, only municipal solid wastes (MSW) were combusted. The picture has changed dramatically, however, since those early days. The RRF has successfully processed hundreds of different residual waste streams since 1994. The list of residuals processed at the RRF is impressive: over-the-counter and bulk pharmaceuticals; off-spec toothpaste in cubic-yard totes; virgin oily debris; ink waste in fiber and steel drums; industrial waste waters; and confidential documents and controlled substances from local law enforcement agencies, pharmaceutical manufacturers, and the Drug Enforcement Administration. This paper describes how residual wastes are managed at the facility, including a discussion of waste inspection activities on the tipping floor, and a description of the various methods by which these materials are fed to the boilers.
Lead and Arsenic Exposure Control for Waste to Energy Furnace Cleaning
Authors: Austin John S. , Croft Michael E.
Published: January 2009

In 1997, the Hampton/NASA Steam Plant implemented a successfully re-engineered wet cleaning process for controlling exposure to lead and cadmium during the cleaning and maintenance of electrostatic precipitators. The following year we were ready to apply the lessons learned to the initial furnace cleaning tasks. As part of the initial process review, industrial hygiene (IH) tests were done during furnace cleaning using the in practice methods. Testing was done for respirable lead and cadmium. Lead exposure was found to be over the action level, but cadmium exposures were just around non-detect levels. May of 1999 the facility became aware, through an IWSA-MWMA-ASME Safety and Health Seminar, that other WTE facilities were testing for arsenic as well. Another set of tests were performed that same month which included tests for respirable arsenic. The results showed that arsenic was present and found to be over the action level, and one test point was especially high during the sifting hopper cleaning part of the procedure. These results were surprising since IH testing for these tasks during 1987 indicated much lower exposures. It was decided the procedures had to be changed. Two process improvement outcomes were targeted: 1) To prevent accidents, injuries and close calls during the furnace cleaning task, a safer procedure for the task of furnace cleaning would be developed. 2) The new procedure must control cadmium, lead and arsenic exposures during furnace and sifting hopper cleaning tasks, to below OSHA Action Levels. The new procedure standardized cleaning methods and included use of water right from the initial entry into the furnace. Operators had respirators upgraded to Positive Pressure Air Purifying Respirators (PAPR) and wore special disposable coveralls. Subsequent Industrial Hygiene testing showed that exposure levels could be reduced to less than the OSHA Action Level and Permissible Exposure Limits for lead and arsenic. The newly developed “wet cleaning” procedure provided a safer standardized procedure that the Operators helped to develop, and Operators feel safer doing the task. The new procedure has also reduced task worker exposures to Lead and Arsenic to below OSHA Action Levels.
Lee County Resource Recovery Facility Expansion Project
Authors: Rosania Sam M.
Published: January 2009

Municipal solid waste from Lee County and Hendry County is processed at the Lee County Solid Waste Resource Recovery Facility (the “Facility”). Lee County (the “County”) owns the Facility, which began commercial operation in December 1994. The Facility’s current permitted capacity is 1,320 tons per day (tpd), provided by two 660-tpd boiler units, at a reference waste of 5,000 Btu. Covanta Energy of Lee, Inc. operates and maintains the Facility under the terms of a Service Agreement with the County that runs through 2014. Covanta also designed and constructed the Facility. The expansion of this Facility will be the first new construction of a municipal waste combustion (MWC) unit since the New Source Performance Standards were adopted. Despite the County’s comprehensive recycling program, the amount of solid waste the County delivers to the Facility has increased each year since the Facility began operation, primarily due to population growth. In 1999, this amount reached the Facility’s guaranteed annual capacity of 372,300 tons. In 2000, the Facility processed over 392,000 tons of municipal solid waste, while the County landfilled nearly 44,000 additional tons of processible waste. Current population projections for Lee and Hendry Counties suggest that processible solid waste generation will continue to increase, reaching nearly 550,000 tons by 2010. Rather than landfilling processible waste generated in excess of the Facility’s current capacity, it is the County’s intention to expand the Facility by adding a third 660-tpd boiler unit which would increase the Facility’s permitted capacity to 1,980-tpd. The original application for the Facility’s Power Plant Site Certification anticipated such an expansion, including provisions for a third 660-tpd MWC unit. Certain provisions for this third unit were incorporated into the Facility’s design and construction as well. These included providing the physical space for the third unit, the physical space for an additional flue for the third unit, and sizing the tipping floor, refuse pit, and certain common equipment for three units. The expansion will require a second turbine-generator unit and expanded switchyard, an extension to the existing turbine-generator building, as well as the addition of a third boiler unit and air pollution control equipment. The expansion will also require modifications to certain equipment and systems common to all boiler units in order to meet the additional capacity requirements of the expanded Facility. As of February 2003, the County is waiting for the Florida Department of Environmental Protection to issue a draft PSD Air Permit and is on scheduled to go before the Power Plant Siting Board in September 2003.
McKay Bay Waste-to-Energy Facility Retrofit Project Closeout
Authors: Schwartz Mark P. , White Thomas M.
Published: January 2009

For NAWTEC10, Messrs. Schwartz and White published and presented a paper on the retrofit of City of Tampa’s 1000-TPD, four-unit McKay Bay Facility. The original facility was constructed in 1967, as an incinerator. The first retrofit of the plant to a waste-to-energy facility occurred in 1985, and the 1999–2002 retrofit (chute to stack) enhanced the facility to current day technologies and environmental standards. This paper reviews both administrative and technical issues for the final project closeout, and describes several construction and operational improvements made in order to improve safety and optimize performance at the plant. Technical items include a remedy for excessive vibrations, addition of an ash conveyor ventilation system, successful use of boiler on-line concussion blasting, and addition of lower boiler furnace cameras.
Long-Term Operating Results: Ash Monofill
Authors: Goodwin Richard W.
Published: January 2009

An ash monofill was studied from 1997 to 2001. Monitoring results of the lined landfill showed viability of liner since groundwater standards were not exceeded. Raw leachate of RCRA heavy metal leachate results show Chromium reaching groundwater standards while Lead, Cadmium and Zinc slightly exceed these standards. An upset incident of premature set-up of lime-laden ash caused a back-up and overflow condition in 1994. Adding water of solubilization and field compaction achieves optimal geo-technical properties and reduces heavy metal leachate. This water addition would have also reduced fugitive dust concerns. These principles of sound engineering management of MWC residues were well-known and widely publicized. If the landfill operator had applied these principles the upset incident could have been avoided. Long-term trends of RCRA heavy metal leachate results show compliance with groundwater standards, although Lead, Cadmium and Zinc exceed these standards. Application of sound engineering placement practice would have reduced these long-term trends. USA Regulatory officials should consider incorporating these principles into residue management recommendations, following Environment Canada’s example. Recognition and implementation of these principles would confirm that incinerator ash can be properly managed — to alleviate concerns — justifying their beneficial reuse.
Health and Safety Issues on Brick, Refractory and Insulation
Authors: Bases Gary J.
Published: January 2009

The steam and power generating industries, like most, have to pay close attention to health and safety issues pertinent to its industry components. Each component of the boiler island has some special and unique issues that must be addressed. Brick, refractory, and insulation are no exception. They have very specific health and safety issues on just about every type of refractory and insulation material available on the market today. Not to mention the health and safety issues associated with the materials of products no longer manufactured but still found on existing construction. These industries must know about the health and safety issues associated with the products to be installed at their facilities. They must also familiarize themselves with those products that exist on their boilers. Ignorance is not an excuse and will save them no money when and if someone breaches an area that has a material that presents a health or safety issue. Proper material selection and proper preventive practices will prevent any potentially dangerous and health threatening issues. Paying close attention and following all health and safety requirements will protect the health and safety of those working in and around brick, refractory and insulation materials.
Fundamental Rheological Modeling and Failure of Multi-Layered Nanostructured Materials
Authors: Kireitseu M. V. , Hui D. , Bochkareva L. V. , Nemerenco I. A. , Nedavniy I. O. , Eremeev S. V.
Published: January 2009

The principal goal of the paper is to reveal whither principal Newton’s fundamentals may give reliable explanations at examining fracture mechanics of multi-layered nanostructured coatings and composites or they should be corrected with new theories. The core of principal Newton’s fundamentals was combined with rheological modeling for describing stress-deformations of nanostructured coatings. Alumina-based or diamonds-containing composites were studied by in-situ cases. The use of indentation at micro and nanoscales with rheological models as a method for determining the fracture of multi-layered brittle coatings is described. Rheological behavior of the model under localized loading and different initial stress and deformation states was studied. Advantage of the method revealed here is that the only quantity to be measured is a deformation or a fracture load. By measuring this minimum load (and that is the only quantity that must be measured) an accurate estimate of fracture may easily be made with application of rheological modeling. Finally, discussion concerned about a scale at which rheological modeling may be effectively applied to examine the fracture mechanics of nanostructured coatings and composites.
Explosion Relief Panels and Their Effect on Gas Explosion Overpressure
Authors: Bakke Jan Roar , Skogrand Per Erik
Published: January 2009

Explosion relief panels are commonly used on offshore installations to improve working environment and at the same time allow venting of gas explosions to control explosion risk. This is very important particularly in arctic regions where requirements for acceptable working environment may easily conflict with requirements for low explosion risk. Explosion relief panels have been tested in low congestion, medium scale explosion tests, and based on such tests it has been concluded that replacing solid walls with relief panels reduces explosion loads significantly. It is not clear whether this conclusion can be extended to real offshore modules, which are significantly larger and more congested. In the present paper the gas explosion simulator FLACS is therefore used to investigate the effect of different wall configurations (e.g. open, solid or relief panels) on explosion overpressure in a large, highly congested offshore module. The objective is to assess whether in reality similar benefits from using relief panels as seen in the experiments can be expected.
Restoring Integrity to Aged Petroleum Production Facilities
Authors: Ciaraldi Stephen W. , Hedges Bill
Published: January 2009

BP and its local predecessor Amoco have produced oil and gas off the east coast of Trinidad for over 30 years. This production originates from eight offshore fields and is transported to onshore terminals through an extensive pipeline network. Gas is further shipped for domestic use or LNG production. Oil is temporarily stored onshore and then tanker loaded for export. Despite excellent business success for the operator and nation, maturing production, long service time and constrained resources have taken a toll on the technical integrity of facilities. In late 2000, a major program to restore integrity was developed, resourced and implementation begun. The restoration strategy was based on a four-step process involving assess, restore, upgrade and sustain. The program addresses the technical integrity of all assets including offshore topsides, subsea structures/pipelines, onshore terminals, tankage and oil/gas exports systems. It also included enhancements to process safety protective systems and development of a comprehensive major accident hazards management system. This paper outlines the many problems, solutions, challenges and successes of the integrity restoration program. It describes the required organizational commitment to a multi-year improvement campaign and a shared vision of sustained, world-class integrity management. In its third year, the program has had significant accomplishments, although there is still much to do. Overall, it has been a strong contributor to continued business success both now and into the future.
A Failure Assessment Procedure for Cracked Pipelines Incorporating a Damage Criterion for Crack Growth
Authors: Dotta Fernando , Hippert Eduardo , Ruggieri Claudio
Published: January 2009

This study extends a micromechanics approach based upon the computational cell methodology to model ductile crack extension of longitudinal crack-like defects in a high strength pipeline steel. Laboratory testing of an API 5L X60 AND x70 pipeline steel at room temperature using standard, deep crack C(T) specimens provide the data needed to measure the crack growth resistance curve for the material. In the computational cell model, ductile crack extension occurs through void growth and coalescence (by cell extinction) within a thin layer of material ahead of crack tip. A simple scheme to calibrate material-specific parameters for the cells is also described. A central focus of the paper is the application of the cell methodology to predict experimentally measured burst pressures for pre-cracked pipe specimens with different crack sizes. The experimental program includes longitudinally precracked pipe specimens with 8 5/8” (209 mm) and 20” (508 mm) O.D. The numerical simulations demonstrate the effectiveness of the cell approach to describe crack growth response and to predict the burst pressure for the tested pipes.
Reliability and Availability Study on Critical Safety Systems of an Offshore Drilling Platform
Authors: Lee Sejoong , Min Joonho , Kim Junhong , Chang Kwangpil , Moon Kiho , Chang Daejun
Published: January 2009

The main purpose of the study is to ensure whether the safety systems of an offshore drilling platform maintain their integrity and perform their duty under probable accident scenarios. This assurance is completed via reliability and availability analysis of the systems, verifying the design outcomes and recommending design and operational changes. The scope is limited to determining the reliability and availability for continuous systems, and only the reliability, often represented probability of failure on demand (PFD), for stand-by systems. Qualitative analysis is to be carried out to identify each failure mode and the sequence of events associated with it for the systems within the scope. Based on the result of qualitative analysis, failure scenarios are logically constructed to comprise basic events and failure effects. The failure data is taken from generic references such as the offshore reliability data handbook (OREDA). In the final analysis, the values of availability for the all systems are quantified to be above 99%. It is considered that the analysis results are broadly acceptable for general safety requirements.
Design Loads Used for Direct Strength Assessment of Merchant Ship Structures
Authors: Zhu Tingyao , Shigemi Toshiyuki
Published: January 2009

This paper summarizes the results of extensive research on the design loads used for strength assessment of merchant ship structures such as tankers, bulk carriers and container ships. The main aim of the research was to develop practical estimation methods of design loads having rational technical backgrounds acting on primary structural members of tankers, bulk carriers and container ships. During this study: 1) The design sea states that closely resemble the actual sea states which are considered as the most severe for hull structures are proposed. 2) The practical estimation methods of the design sea states are proposed by parametric studies using the results of series calculation of representative merchant ships. 3) The practical estimation methods of design regular waves resulting in the same level of stresses with that induced in irregular waves under the design sea states are proposed. 4) The practical estimation methods of the design loads such as ship motions, accelerations, hull-girder bending moments and hydrodynamic pressures that are induced under design regular waves are briefly introduced. The findings in this study have been summarized and implemented in the new design standards for tanker, bulk carrier and container ship structures. (Guidelines for Tanker Structures, 2001, Nippon Kaiji Kyokai. Guidelines for Bulk Carrier Structures, 2002, Nippon Kaiji Kyokai. Guidelines for container Carrier Structures, 2003, Nippon Kaiji Kyokai.)
The Wave Focusing Effect of a Parabolic Wall
Authors: Wang J. , Calisal S. M. , Mikkelsen J. , Zealand S.
Published: January 2009

The energy generation efficiency of a wave energy conversion system is in general proportional to the capacity of wave energy capture of the system. In various wave energy conversion systems, a configuration with parabolic shape has shown advantages in wave capture dynamics. This paper presents an experimental investigation into the wave focusing and elevation in a parabolic wall area with a Laser Wave Height Measurement equipment named as IVP Ranger SC386. In the experiment, the tested waves were described by a dimensionless factor WF which consists of wave parameters and the parabolic wall size. The WF increases with wave relative size to the model. The tested wave obliquities to the parabolic wall were 10 and 20 degrees in addition to the normal incident waves. A tube with an inner diameter 7.5cm, representing a chamber for oscillatory water columns compressing air, was mounted at the focus area. The elevations of wave height inside the tube with a sealed and an open top, as two different cases, were also measured. Furthermore the wave forces acting on the parabolic wall were measured using load cells. The analysis of the experimental results revealed that the parabolic wall was able to significantly elevate wave heights by up to 2.5 times. Within 10 degrees the wave obliquity effect can be neglected for both forces acting on the parabolic wall and wave height elevated by the parabolic wall. A prediction equation for focusing wave height was developed from the experimental results and the parabolic focusing principle.
Experimental Study of Suction Installation of Caissons in Dense Sand
Authors: Tran Manh N. , Randolph Mark F. , Airey David W.
Published: January 2009

Physical models have been developed to investigate suction installation of caisson foundations in fine-grained dense silica sand. The main controlling factor, pumping rate, was found to have significant influence on the differential pressure result across the caisson base. Rapid pumping is unlikely to bring any adverse effect to the installation process, even applied at very shallow initial wall penetration depth. Quick installation, with the exception of caissons with wall-to-diameter (t/D) ratio larger than 1%, appeared to be beneficial in reducing the excessive sand heave. Observations showed that caisson geometry and surcharge also affected the installation performance. Although requiring only marginal increase in suction pressure to install, caissons with thicker walls created substantially higher sand heave during installation. Varying the absolute caisson size did not seem to affect the suction pressure for a given t/D. Seepage flow was also calculated during each test, and found to increase with deeper skirt penetration.
Dynamic Analysis of a Towed Underwater Vehicle System: Model Validation
Authors: Haugen Gry Karin , Grahl-Madsen Mads
Published: January 2009

An integrated system consisting of two towed sub-sea vehicles and a free-floating probe is being developed to perform mapping and quantitative estimations for fish and plankton. A thorough understanding of the dynamic behaviour of the towed vehicle system is essential for a successful design, and a dynamic model that can accurately describe the vehicle behaviour under the influence of a wide variation of conditions, is necessary. This paper discusses two different approaches for the dynamic analysis of a towed vehicle system. Analyses are performed using the commercial available simulation program MOSES. Further the 2D equations of motion for the towed vehicle are developed and solved in Matlab using a simple cable model.
Cool-Down Temperature Abnormity Caused by Subsea Pipeline Topography
Authors: Chin Y. Doreen
Published: January 2009

An abnormity of temperature trend during cool down has been observed. During shut-in of insulated pipeline and riser systems that carry multiphase wellstream, the temperature at pipeline segments with large geometrical variations may decrease below the local ambient temperature. The low temperatures at these locations increase risk of hydrate formation during system cool-down. The cause of such abnormity may be explained by the mass transfer between gas-liquid interface, the phase re-allocation, and inner energy re-distribution due to the combined effects of gravitational and buoyancy forces. Pressure, mass flowrate, fluid compositions, flow orientation, and external and internal heat transfer during system cool-down are the key factors for the phase-redistribution between gas and liquid, and along the system. Susceptibility of a system for cool-down temperature abnormity should be assessed during design stage and operation procedures should be developed to manage it. An explanation of the governing mechanisms of this phenomenon is given in this paper, for a wide range of system parameters. The discussions are based on a series of theoretical and numerical studies of gas/condensate and oil/gas flows in subsea flowline and riser system after system shutdown.
A Validation Study for Tank Sloshing Using a Navier-Stokes Solver
Authors: Rhee Shin Hyung
Published: January 2009

The present study is concerned with the liquid tank sloshing at low filling level conditions. The volume of fluid method implemented in a Navier-Stokes computational fluid dynamics code is employed to handle the free-surface flow of liquid sloshing. A geometric reconstruction scheme for the interface representation is employed to ensure sharpness at the free-surface. The governing equations are discretized by second order accurate schemes on unstructured grids. Several different computational approaches are verified and numerical uncertainties are assessed. The computational results are validated against existing experimental data, showing good agreement. The capability is demonstrated for a generic membrane type LNG carrier tank with a simplified pump tower inside. The validation results suggest that the present computational approach is both easy to apply and accurate enough for more realistic problems.
Wave Run Up as Important Hydrodynamic Issue for Gravity Based Structures
Authors: Loots Erwin , Buchner Bas
Published: January 2009

Gravity Based Structures (GBS) are now seriously considered as LNG import terminal. When the environment of wind and waves is strongly directional, with an optimum orientation of the GBS a significant shielding can be achieved, reducing the weather downtime. However, the application of Gravity Based Structures also results in a number of hydrodynamic challenges, of which wave run-up is the subject of the present paper. Because of the optimized heading of the GBS beam to the dominant sea direction, typically the survival conditions will be beam to the GBS as well. This means that the wave run-up and possible green water on the deck of the GBS is a problem that needs serious evaluation. This run up problem is studied numerically with an improved Volume Of Fluid (iVOF) method. Results are presented concerning the generation and propagation of waves, the influence of deflectors, and the effect of wind.
Research on Applicability of New Materials to Marine Structures in Tropical Climates: Specimens Exposed for 3 Years
Authors: Tomosawa Fuminori , Tsujikawa Shigeo , Ono Tadashi , Yonemaru Keisuke , Takizawa Shozo , Kugai Yasuo , Miura Hideo
Published: January 2009

New structural materials that are light and durable are anticipated to reduce the running and maintenance costs of structures exposed to harsh marine environments, such as offshore oil production facilities, thereby reducing their lifecycle cost. This study aims to investigate the applicability of new materials to marine structures, focusing on their durability. To this end, a 5-year exposure test has been conducted from 1999 on 3 types of specimens (for corrosion observation, tension testing, and joint strength testing) made of 21 selected materials (6 nonferrous metals, 8 steels, 4 composite materials, and 3 rope materials). The specimens are exposed at 3 sites: Okinotori-shima and Miyako-jima, corrosive environments with high temperature and humidity, and a thermo-hygrostatic room in a laboratory. In 2004, the fifth and the last year of the ongoing exposure testing, the results of the observation and experiments of specimens recovered in 2003 after exposure for 4 years are subjected to analysis. The authors have already reported the detailed plan of the exposure test, initial performance of the specimens, and findings obtained each year from observation and testing. This paper primarily reports on the results of appearance observation of specimens at Okinotori-shima and Miyako-jima carried out in 2002, as well as the findings from observation and experiments on specimens exposed for 3 years at Miyako-jima. The state of corrosion at each site was grasped during the appearance observation. No appreciable difference was observed between the specimens exposed to natural environments at Okinotori-shima and Miyako-jima. Specimens recovered from Miyako-jima were subjected to appearance observation and experiments to grasp the state of corrosion. The strength of metal specimens that had shown strength losses a year earlier became even lower. Pitting corrosion increased on specimens on which surface corrosion had been found a year earlier. Also, surface corrosion was newly recognized on specimens of certain types on which no corrosion had been observed before. These phenomena indicate progress of corrosion due to exposure to natural environments. Comparison of these data with existing data of exposure to other natural environments revealed particular fierceness of the environments adopted for this study.
Axial and Lateral Coupled Response of a Deepsea Riser for Scientific Drilling
Authors: Suzuki Hideyuki , Takano Kotaro , Enomoto Kazuo , Oka Noriaki
Published: January 2009

Axial and lateral coupled response of deepsea drilling risers in hang-off condition was investigated. Lateral oscillation of riser has a possibility of being excited by axial tension fluctuation. The lateral response can be described by Mathieu’s equation of parametric oscillation. Numerical analysis method was formulated and verified by comparisons with experimental results. Stability conditions were clarified using the numerical method. Stability of the 4,000m riser for Scientific Drilling was also investigated and guideline for design of ultra deepwater risers was proposed.
Failure and Post-Failure Mechanics of Submarine Landslides
Authors: Brandes Horst G. , Wang Shentang
Published: January 2009

Theoretical contexts for each of the stages associated with underwater landsliding can be postulated with reasonable confidence, although specific constitutive models require additional work. Also still missing is a comprehensive numerical framework for predicting displacement fields from small pre-failure and post-depositional sediment volume changes and distortions to large-scale inertial sediment wasting. A particular promising modeling approach is outlined herein.
Investigations on the Behavior of Vertical Production Risers
Authors: Morooka C. K. , Coelho F. M. , Kubota H. Y. , Ferrari J. A. , Ribeiro E. J. B.
Published: January 2009

The present paper describes the behavior of a vertical riser in waves, currents and which is excited by displacements at the riser top. Fundamental equations for riser behavior are described and the Ferrari&Bearman model [4] is applied to estimate hydrodynamic load for “in-line” and transverse directions of the riser. Solution for riser behavior is obtained in time domain, calculations are performed for deepwater field production scenario and discussions are addressed. The influence of variation of riser diameter and drag coefficient along its length, the presence of floaters and effect of petroleum fluid flowing in the riser are investigated. Moreover, effects of the upper and bottom end conditions of the riser on its behavior are also taken into account in the analysis.
SOS: A New Design Concept for Seaway Independent Oil Skimming
Authors: Clauss Gu¨nther , Abu Amro Mazen
Published: January 2009

Tanker catastrophes like the sinking of the “Erika” off the coast of Brittany and the “Prestige” off the coast of Spain revealed the shortcomings of existing oil combating systems to operate in open seas during severe weather. This paper presents various oil recovery systems of the German oil combating fleet and an analysis of their associated hydrodynamic problems. Design improvements for increasing operability and efficiency of oil recovery systems are proposed, taking advantages and drawbacks of existing oil recovery vessels into account. A new design concept is applied to the development of a Seaway Independent Oil Skimmer (SOS), which is presently being investigated at TU Berlin. A skimming module based on a new working principle enables the future generation of oil recovery vessels to operate in rough sea states. To evaluate the new oil-skimming system numerical simulations are conducted for a wide spectrum of operating conditions. The results are confirmed by experimental investigation including oil layers.
Avoiding Hydrogen Embrittlement Stress Cracking of Ferritic Austenitic Stainless Steels Under Cathodic Protection
Authors: Woollin P. , Gregori A.
Published: January 2009

The paper presents the results of a programme designed to define the material, stress and environmental factors controlling sensitivity of ferritic-austenitic stainless steels to hydrogen embrittlement stress cracking when exposed to cathodic protection. Factors examined in small and large-scale tests include microstructural coarseness, phase balance and hardness of a range of parent steels and welds. The results are presented in terms of threshold strain and normalised stress to develop hydrogen embrittlement stress cracks. The effects of microstructure and applied potential on crack initiation and propagation are described. Recommendations are made with respect to the strain/normalised stress levels for ferritic-austenitic steels under cathodic protection.
Analysis of Flow Induced Vibrations Effect on Service Life of Unbonded Flexible Pipe
Authors: Tan Zhimin , Ethridge Andrew , Sheldrake Terry , Clements Richard
Published: January 2009

High frequency vibrations have been reported on flexible pipes for gas export risers installed on platforms offshore in the North Sea. The vibrations are believed to be caused by internal flow vortex shedding as pressured gas passes through the bore at a certain speed. The vibration frequency is typically above 150Hz resulting in approximately 100 billion cycles over the service life. This paper presents analytical models developed to assess the alternating stresses of the strength components induced by the flow-induced carcass vibration, and the consequent influence over their fatigue damage and overall pipe structure integrity. The studied strength layers include the interlocked carcass layer, interlocked hoop strength (pressure armor) and axial tension layers. The models illustrate the behavior of these components inside both the end fitting structure and the free suspended section. The study of a large 15 inch inner diameter gas export riser is presented with test measurements reported in literature.
Optimal Inspection Methodology for Offshore Structures Based on an Economic Decision Theory
Authors: Florentino Saul , De Leon David , Silva Jorge
Published: January 2009

About 200 marine platforms are installed in the Mexican sector of the Gulf of Mexico so that maintenance and inspection schedules play an important role to avoid excessive structural deterioration of the oil facilities and at the same time to keep the facilities within acceptable safety margins. Large costs associated with inspection and repair actions moved managers towards the application of an optimal strategy in order to minimize inspection expenses. For these purposes, it is necessary to consider deterioration process such as fatigue crack growth under the influence of uncertain wave loading which is the dominant force while effort is focused on maintaining structural integrity and safe production. This paper presents an optimal inspection methodology for offshore structures based on an economic decision theory, bearing in mind that large costs are associated with structural failure and extensive inspection and repairs. A system failure analysis of a given sub set of the critical structural components is included as well as a mathematical framework for the assessment of failure and repair cost associated.
Experimental Study of Scour Due to Breaking Waves in Front of Vertical-Wall Breakwaters
Authors: Hasanzadeh Daloui Ali , Jamali Mirmosadegh
Published: January 2009

Scour is an important cause of instability of breakwaters. In case of vertical-wall breakwaters, toe scour can cause collapse of the whole structure. This paper is concerned with an experimental study of the effects of regular breaking waves on scour at toe of vertical-wall breakwaters. Experiments were carried out in a wave flume with regular waves for two cases of a beach with and without a breakwater. Bed profiles and scour depths for various wave heights, periods and depths were recorded. For the case of a beach without a breakwater, the observed bed profile types are compared to predictions. For the case of a beach with a breakwater, factors affecting the scour are investigated, and an empirical equation for scour depth at toe of a vertical wall is proposed.
Probabilistic Modelling for Reliability Analysis of Jackets
Authors: Mathisen Jan , Ronold Knut O. , Sigurdsson Gudfinnur
Published: January 2009

Experience from recent reliability analyses of jacket platforms is used to discuss selected aspects of probabilistic modelling in more detail. These modelling details can have a significant effect on the computed reliabilities. An overview of basic considerations and failure modes in jacket reliability analysis is included to set the various details into context. Ultimate limit states for jackets in relatively shallow water are emphasised; i.e. quasi-static structural response is applicable. The following topics are considered: (a) Failure modes and some requirements to load and resistance analysis. (b) Directionality in loading and resistance. (c) Random periods of individual extreme waves. (d) Foundations — axial and lateral capacity modelling for multiple piles and model uncertainty for pile capacity.