This thesis describes a new general purpose dynamic process simulator applied to a natural gas liquefaction plant. More specifically, the Multi Fluid Cascade Process (MFCP). MFCP is the “Statoil Linde LNG Technology Alliance” - a proprietary and patented process for LNG production. This utilizes plate fin and spiral wound heat exchangers, produced by Linde AG, and Nuovo Pignone’s centrifugal compressors. This LNG technology is now being implemented for the Hammerfest baseload LNG project, Snøhvit. The simulator is based on first principle conservation laws for energy and mass, and a simplified quasi-steady state momentum equation. Unit models for the process equipment (tanks/pipes, separation tanks, valves, liquid expanders, pumps, compressors, heat exchangers, and PI controllers) are described using rigorous thermodynamics. Equilibrium is assumed for all unit models, and equilibrium and physical properties are predicted with the Swoave-Redlich-Kwong or the Peng-Robinson equation of state. Two different model approaches are compared in this work. One approach conserves energy in an enthalpy state, and the other conserves internal energy, the HP formulation and UV formulation respectively. The HP formulation defines a dynamic state for the pressure, and splits the integration of the fast and slow dynamics. The pressure states and the algebraic flow relations are solved by a fully implicit Euler method, while the internal unit model equation is solved locally with tailormade integration routines. The UV formulation, utilizes an analytical Jacobian, and is integrated with both a 1-stage Rosenbrock and freeware BDF codes. The UV formulation generates an analytical Jacobian from physical property partial differentials. These property differentials are calculated from a first order approximation of the equilibrium. The equilibrium equations are linearized in dynamic state variables to produce partial differentials of the internal flash variables. The simulator is tested on a portable PC. The full MFCP LNG plant is simulated with a fixed time step of 1.0 seconds, for both the HP and UV formulations. The HP formulation has 611 ODE states. The UV formulation uses the 1-stage Rosenbrock method integrating a system with 1025 ODE states. The case simulated is a set point step for the LNG temperature controller. The plant is simulated over 9000 seconds. The major process dynamics are sampled every second, and plotted. The average performance of both formulation is better that 7 times real time. The worst local performance of the UV formulation is 1.7 times faster than the HP formulation, but more than 6 times faster than real time. The HP and UV formulations gave significantly different dynamic predictions. The BDF codes proved too slow for practical use on the MFCP configuration. The dynamic simulators in industry today are typically using a HP formulation, with precalculated thermodynamic data stored in look-up tables. The simulations of the full LNG plant show that simulators, utilizing EOS equilibrium descriptions, soon will be able to compare with modern industry simulators.

Det nya svaveldirektivet för hur mycket svavel fartygen i Östersjön och Nordsjön får släppa ut börjar gälla 2015. Detta har stor betydelse bland annat för färjerederierna som trafikerar inom SECA i Östersjön och Nordsjön. Idag finns det ingen självklar lösning på hur färjerederierna ska uppfylla det nya svaveldirektivet, så hur har de tänkt klara det? Hur såg färjerederiernas resonemang ut innan de valde vilken teknisk lösning de skulle använda sig av? För att få svar på frågeställningen används en kvalitativ metod. Rådata som varit till grund för slutsatsen har samlats in från sju olika talespersoner för färjerederier i Norden. Dessa talespersoner har varit insatta i fartygens drift och har goda kunskaper om fartygen och deras framdrift. I slutsatsen har vi sammanfattat resultaten av olika tekniska lösningar som rederierna har diskuterat under intervjuerna. Slutsatsen av undersökningen är att de flesta av färjerederierna kommer gå över helt till MGO eller WRD för att klara de nya svaveldirektivet år 2015, tills något bättre alternativ finns. De inblandade rederierna och deras talespersoner har tilldelats fingerade namn. / The new sulphur directive, concerning the quantity of sulphur that vessels in the Baltic Sea and North Sea are allowed to discharge in form of exhaust gases, takes effect in 2015. This has a great impact on the shipping companies traveling the Baltic- and North Sea SECA. Today there are no obvious solutions on how the ferry companies will be able to follow the new sulphur regulations, so how are they supposed to cope? In what way did they discuss matters before deciding upon which technical solution to choose? To answer the questions a qualitative method was used. Data, that has been the basis of this paper, has been collected from spokespersons from seven ferry companies in Scandinavia. These spokespersons have been familiar with the machinery on board and have significant knowledge of their vessels. In the conclusion we have summarized the results of different technical solutions that the shipping companies have discussed during the interviews. The conclusion of this paper is that most of the ferry companies will use MGO or WRD to cope with the new sulphur regulations until a better alternative is introduced. In order to maintain anonymity, the names of participating shipping companies and interviewees have been changed.

BELEVE son las iniciales de la siguiente expresión inglesa "Boiling Liquid Expanding Vapor Explosion" que traducido librementes ignifica "Explosión de los Vapores que se expanden al hervir un líquido".La ELEVE es comúnmente definida como la ruptura en varios pedazos de un recipiente, con proyección a grandes distancias, superiores a las que las desplazarían la simple energía de un estallido, que se da en determinadas circunstancias, siendo necesario, pero no suficiente, que el líquido contenido en el recipiente, posea una temperatura superior a la que le correspondería tener si estuviera a la presión atmosférica normal. Por tanto, la temperatura de ebullición debe ser bastante menor que la temperatura a la que se encuentre la masa líquida en el recipiente, es decir, lo que se llama o denomina líquido sobrecalentado.El fenómeno ELEVE es una manifestación exclusiva de los líquidos sobrecalentados, no debiéndose confundir con las explosiones que se producen en los recipientes que solamente contienen gas, pues las energías desarrolladas por la explosión de este último, no son en absoluto comparables a las elevadas del fenómeno ELEVE.En el caso de que el fenómeno ELEVE se manifieste en un recipiente que contiene líquido que es químicamente reactivo o combustible, agrava el problema de la ELEVE propiamente dicho, ya que anteriormente se ha indicado que un ELEVE se puede producir en una caldera de vapor de agua.Las condiciones necesarias que se han de dar simultáneamente.

Taiwan is the major country of importing LNG. In this paper discussed LNG cold energy recovery used in cold storage warehouse and other energy conservation systems. In the cold storage warehouse systems that showed the less temperature of cold storage warehouse the more exergy efficiency and the best exergy efficiency is 30%. Base on thermoeconomic analysis there was the optimal operation temperature at -70¢J. In the purifier nitrogen system (PNS), the investigation indicated the best efficient operating temperature at -150¢J. But with economic analysis the optimal design temperature of this PNS was -130¢J. And the last energy conservation system was the running power plane. In this research studied the power planes used LNG cold energy as inlet air-cooling systems. According to the investigation that showed the systems increased power output up to 14.4¢H in the 4.5¢J of inlet air cooling temperature. And these systems also improved the heat rate of power planes about 0.98%. The conclusions presented that the potentialities of LNG cold energy are huge, and with proper engineering and economic analysis could make these energy conservation systems more feasible.

A competitive gas-to-gas trading market has yet to emerge in Asia. Yet in spite of the various barriers and restrictions, the trend of liberalization seems to inevitable. How a natural gas trading market just might develop in East Asia is what this thesis explains and predicts. Moreover, it lays out what the preconditions for the changes are, and what the costs and benefits from such changes may be. Considering Asia’s current market situation, the wholesale competition model could be a practical option for Asia’s gas markets. A critical role in building up the gas-to-gas trading market will be played by China. In the first stage of market liberalization, China alone can be expected to form its own trading hub on its east coast, say in Shanghai. If the transactions of the trading hub work smoothly and the set prices lower than oil-linked gas prices, then other gas-importing countries would likely join the trading hub by interconnecting with a physical pipeline. / text

The safety and security of liquefied natural gas (LNG) facilities has prompted the need for continued study of LNG mitigation systems. Water spray systems are widely recognized as an effective measure for dispersing LNG vapor clouds. Currently, there are no engineering guidelines available for water curtain applications in the LNG industry due to a lack of understanding of the complex interactions between the LNG vapor cloud and water droplets. This research applies computational fluid dynamics (CFD) modeling to investigate the forced dispersion of LNG vapor using upward-oriented full-cone spray nozzles. A Eulerian-Lagrangian approach was applied to simulate the energy and momentum exchange between the continuous (gas flow) and discrete (droplets) phases. Discussed are the physical parameters that are essential inputs to the CFD simulation of the water spray-LNG system. The experimental data collected from the Mary Kay O’Connor Process Safety Center’s outdoor LNG spill work in March 2009 at the Brayton Fire Training Field were used to calibrate the physical parameters. The physical mechanisms of the water spray application were investigated using LNG forced dispersion modeling. The effects of momentum imparting from the droplets to the air- vapor mixture, thermal transfer between the two phases (droplet/vapor) and effects of various levels of air entrainment rates on the behavior of the LNG vapors are evaluated. Lastly, the key parametric dependences of the design elements for an effective water curtain system are investigated. The effects of different droplet sizes, droplet temperatures, nozzle cone angles, and installation configurations of water spray applications on LNG vapor behavior are analyzed. This work aims to investigate the complex interaction of the water droplet-LNG vapor system, which will serve in developing guidelines and establishing engineering criteria for a site-specific LNG mitigation system. Finally, the potentials of applying CFD modeling in providing guidance for setting up the design criteria for an effective forced mitigation system as an integrated safety element for LNG facilities are discussed.

Federal regulation 49 CFR 193 and standard NFPA 59A require the use of validated consequence models to determine the vapor cloud dispersion exclusion zones for accidental liquefied natural gas (LNG) releases. For modeling purposes, the physical process of dispersion of LNG release can be simply divided into two stages: source term and atmospheric dispersion. The former stage occurs immediately following the release where the behavior of fluids (LNG and its vapor) is mainly controlled by release conditions. After this initial stage, the atmosphere would increasingly dominate the vapor dispersion behavior until it completely dissipates. In this work, these two stages are modeled separately by a source term model and a dispersion model due to the different parameters used to describe the physical process at each stage. The principal focus of the source term study was on LNG underwater release, since there has been far less research conducted in developing and testing models for the source of LNG release underwater compared to that for LNG release onto land or water. An underwater LNG release test was carried out to understand the phenomena that occur when LNG is released underwater and to determine the characteristics of pool formation and the vapor cloud generated by the vaporization of LNG underwater. A mathematical model was used and validated against test data to calculate the temperature of the vapor emanating from the water surface. This work used the ANSYS CFX, a general-purpose computational fluid dynamics (CFD) package, to model LNG vapor dispersion in the atmosphere. The main advantages of CFD codes are that they have the capability of defining flow physics and allowing for the representation of complex geometry and its effects on vapor dispersion. Discussed are important parameters that are essential inputs to the ANSYS CFX simulations, including the mesh size and shape, atmospheric conditions, turbulence from the source term, ground surface roughness height, and effects of obstacles. A sensitivity analysis was conducted to illustrate the impact of key parameters on the accuracy of simulation results. In addition, a series of medium-scale LNG spill tests have been performed at the Brayton Fire Training Field (BFTF), College Station, TX. The objectives of these tests were to study key parameters of modeling the physical process of LNG vapor dispersion and collect data for validating the ANSYS CFX prediction results. A comparison of test data with simulation results demonstrated that CFX described the physical behavior of LNG vapor dispersion well, and its prediction results of distances to the half lower flammable limit were in good agreement with the test data.

This diploma thesis determines potential benefit of shale gas and its influence on price of gas on European market. For this purpose was chosen two variants, which have the best chance to decrease price of gas on European market. The first variant is extraction of shale gas directly in Europe. The size of deposits and cost estimates indicates the biggest potential from both variants. Possible extraction could be able to decrease significantly price of gas on European market. Nevertheless the present attitude of Europe to extraction can limit this potential. The second variant is import of LNG, which have already helped to decrease price of gas significantly in many European countries. Nevertheless its possible influence on price decline of gas is limited. Expenditures connected with LNG prevent to greater price decline on the possible level of extraction. Moreover Europe has to face to great competition from Asia, where considerable part of gas supply move to. Final benefit of LNG will depend mostly on the size of available supply.

The combination of the continuously growing demand of energy in the world, the depletion of oil and its sharp price increase, as well as the urgent need for cleaner and more efficient fuels have boosted the global trade of liquefied natural gas (LNG). Nowadays, there is an increasing interest on the design philosophy of the LNG receiving terminals, due to the fact that the existing technologies either use seawater as heating source or burn part of the fuel for regasifying LNG, thus destroying the cryogenic energy of LNG and causing air pollution or harm to marine life. This investigation addresses the task of developing novel systems able to simultaneously regasify LNG and generate electric power in the most efficient and environmentally friendly way.    Existing and proposed technologies for integrated LNG regasification and power generation were identified and simple, efficient, safe and compact alternatives were selected for further analysis. A baseline scenario for integrated LNG regasification and power generation was established and simulated, consisting of a cascaded Brayton configuration with a typical small gas turbine as topping cycle and a simple closed Brayton cycle as bottoming cycle. Various novel configurations were created, modeled and compared to the baseline scenario in terms of LNG regasification rate, efficiency and power output. The novel configurations include closed Rankine and Brayton cycles for the bottoming cycle, systems for power augmentation in the gas turbine and combinations of options. A study case with a simple and compact design was selected, preliminarily designed and analyzed according to characteristics and costs provided by suppliers. The performance, costs and design challenges of the study case were then compared to the baseline case. The results show that the study case causes lower investment costs and a smaller footprint of the plant, at the same time offering a simple design solution though with substantially lower efficiencies.

The use of natural gas as a primary energy source has increased over time and is expected to increase even further in the near future. Cyprus and Israel, two countries in the Eastern Mediterranean, have recently made major offshore discoveries of natural gas, sufficient enough to cover their own needs for at least the next few decades and use an even greater amount for export. In this project, the software MESSAGE was used to conduct modelling of the two countries’ energy systems. Projections were made until 2050 of the electricity generation in each country from each major energy source under different scenarios and the possibility of exporting electricity, liquefied natural gas (LNG) or gas-to-liquid products (GTL) was assessed.