Sharif Digital Repository

Many technologies should be applied for transportation or consumption of natural gas. There are many different ways for transporting natural gas from origin of production to the location of consumption which the simplest way is transportation via pipelines but for transportation of natural gas for long distances, we can not use this method in this way we should apply other technologies such as converting the natural gas to the liquid state. For using this method, first we should liquefy the natural gas up to -162 degree of centigrade at the atmospheric pressure and then transport it with large cargo ships. By using this method, the transportation costs are decreased in compared with the... 

This project examines four alternatives such as pipelines, oil injection wells, LNG & GTL in the purpose of Iran gas utilization. In this Project four strategies using cost/benefit analysis are examined. For this purpose, at first the cost of inlet feed gas per Mmbtu are calculated. Then regarding various scenarios of average world gas prices for the following thirty years, the cost & benefit of any way will be counted. Then with the use of energy security, the project will make energy policy. For this purpose, Shannon indicator will be used as one of the most reliable indicators. Due to the of use this indicator, the popular project will be chosen accordingly as a certain amount of gas the... 

Natural gas (NG) has emerged as an alternative energy source in transportation sector as it provides clean combustion and hence lowers exhaust pollution. NG can be stored as an adsorbed phase in porous materials and is referred to ANG. The use of adsorbent materials for storing NG, at relatively low pressure (3.5–4 MPa), is a possibility for making ANG technology competitive with CNG. Among all adsorbents, carbon nanostructures with pore diameter (0.8-1.4 nm) has shown the highest adsorption capacity of natural gas. In the present study, cellulose has been used as the carbonaceous precursor and Activated Carbon (AC) has been prepared using hydrothermal carbonization of cellulose followed by... 

With the huge natural gas reservoir in Iran, LNG production processes have a great attraction for the gas industry. The main goal of this project is the design of a skid mounted of a small scale LNG unit. A pretreatment unit was designed which includes two adsorption towers. In these towers, the type 13X adsorbent, eliminate traces of CO, N2 and H2S. For the cryogenic side a N2 expansion cycle was considered, after studying different cycles. It is found that N2 expansion cycle is one of the best methods for mini LNG production unit. In this process N2 gas was compressed to 35 bar in two stages and after precooling, enters to an expander to produce the -165 C cold in a cold box. The natural... 

This study will examine the interests of Iran in entering one of the largest and most outreaching LNG markets which is China. In order to examine these interests, understanding China's policy on importing LNG and the competitive environment in this market is necessary. First, the decision theory is used to simulate China's policy on adjusting the import mix during the demand growth period of 2011 to 2017.This provides a simulated picture of its policy on increasing demand for the 2020. Then, the behavior of other LNG exporting countries to China is analyzed using game theory approach. By analyzing the sensitivity of the parameters in which uncertainty exist, it was revealed that Iran's... 

In this project, theoretical and experimental study of methane adsorption on Multiwall Carbon Nano-Tubes (MWCNT) has been performed. This study has been conducted in the way to achieve a suitable method for methane storage and transportation. To carry out the experiments, the volumetric method was used up to 500 psia at various temperatures of 298.15 K, 303.15 K, 308.15 K. The effect of moisture was also studied at 298.15 K. Also, various adsorption isotherms were used to model the experimental data collected in this work. The results showed that the amount of methane adsorbed on the MWCNT can decrease with increasing the moisture and temperature of the adsorption cell. In order to... 

Combustion and NOx emissions were simulated by quasi-dimensional and ratereaction methods respectively in a turbocharged CNG engine. Mean-value turbulence modeling was carried out during compression and combustion processes to simulate combustion process better. The most appropriate NG flame speed for the CNG turbocharged engine was applied and ignition delay was ended when flame radius became more than turbulence integral length scale. Hemispherical flame propagated from spark gap center and its intersection with reciprocating Mexican-hat piston bowl was calculated analytically. Thermal boundary layer, as a novel approach, was considered in the simulation and a better agreement of predicted... 

The Darcy’ law is valid for low velocity or low Reynolds number where merely viscous force is responsible for pressure loss in the porous media. At higher velocity, because of inertial forces and turbulency, the pressure loss would be higher than Darcy’ law estimates; therefore at these flow regimes the Darcy’ law is no longer valid. Hence, consideration of Non-Darcy flow effect is necessary to sufficiently model high gas velocity effects. The velocity is high in gas reservoirs especially those ones that are considered for underground gas storage. In this study, the effects of Non-Darcy flow on several parameters such as; estimation of differential pressure, flowing bottom hole pressure,... 

Acidic gases separation from hydrocarbon mixtures is very important in natural gas industry. In this study, the separation of CO2 and H2S from CH4 investigates by experimental and molecular dynamics simulation approaches. For achievement to this goal, it is used two polymeric families, as be divided to polyurethanes and PEBAX copolymers. It is used 4 polyurethane membranes as are named PU-1, PU-2, PU-Ether, and PU-Ester from polyurethanes group. Also, it is applied 5 PEBAX commercial membranes have be known PEBAX-2533, PEBAX-4033, PEBAX-5533, PEBAX-4011, and PEBAX-1074. It is compared between simulation and experimental works and found that there is good agreement between... 

Project Finance is a novel approach in financing big projects. High debt ratio, independency to promoter credit and establishing a special purpose company, are some of project finance characteristics that could be very beneficial in some projects. Liquid Natural Gas (LNG) is a solution for exporting natural gas to far destination. As economical and environmental benefits of using natural gas have been increased in recent years, LNG industry has been experienced rapid growth. In this project we analyze project finance and then describe economical motivation of using this method in LNG industry of Iran.

 

In the present work, the possibility of using a cross flow microchannel heat exchanger in cryogenic service for natural gas liquefaction has been numerically investigated using 3D computational fluid dynamics approach. Microchannels of rectangular and triangular cross section with a hydraulic diameter of 0.667 and 0.472 mm respectively have been constructed in Gambit and Fluent is used as the solver of numerical simulations.For solver’s equations validation, the existing experimental data on flow of water through rectangular microchannels has been modeled by CFD. Comparison of CFD results with experimental data shows a good agreement.Both models are constructed of three distinct layers. In... 

Supersonic separation is a modern technology which is used in petroleum’s industry. Supersonic flow is obtained by converging-diverging nozzle in which by decreasing pressure and increasing fluid’s velocity, we can reach low temperature which is required for separation. After separation in low temperature, pressure is recovered via normal shockwave or a second nozzle. In the case of using second nozzle, fluid’s velocity is decreased and its pressure is increased. In these separators, we have two important issues: Separation efficiency and Pressure recovery . On the other hand, nozzle’s performance depends on two sets of factors: Factors related to nozzle’s geometry and Factors related to... 

Iran has the second largest gas reserves in the world with huge gas reserves about 32 trillion cubic meters. The expansion of gas exports in recent decades has been accompanied by liquefied natural gas exports, with the LNG industry growing rapidly due to the inability to export gas via pipeline to distant markets. The expansion of the LNG industry around the world, there have been various markets for this product that the Southeast Asian market being the largest market for this product and Japan is the largest importer in this sector.Specific mechanisms of the Japanese market, which have separated it from the rest of the LNG importing countries, are the extension of long-term contracts for... 

Natural gas liquefaction is a gas refrigeration technology, which enables the export of natural gas worldwide, in liquids formed and stored at very low temperatures. In this project, a plate-fin type of heat exchanger, which is used for liquefaction of natural gas (mainly methane) at very low temperatures, has been investigated. The most important and effective part of this gas refrigeration cycle is the cold box heat exchanger. The cold box consists of two or more floors in which some sorts of fins are installed in each floor. In this simulation, the three-sream heat exchanger is designed in such a way that the input temperature of the natural gas is about 200 K and the output is 145 K at a... 

Today, shipping of liquefied natural gas has a considerable share in the global gas trade. Efficient design, optimal operation, and precise control of process variables in the gas liquefaction process decrease energy consumption for LNG production. Understanding the dynamic behavior of a liquefied natural gas unit helps engineers to make the correct choice of controlled variables and tuning controllers. Through a dynamic simulation, this understanding can be achieved. Simulation of a multi-stream heat exchanger, as the heart of the gas liquefaction process, is a challenge of studying this process. In this study, two dynamic models governing a multi-stream heat exchanger in Aspen Plus... 

In the upstream part of the natural gas supply chain, the refinery is one of the most complex and energy-intensive sectors that has received little attention. Enterprise-wide optimization, that uses mathematical programming in a centralized and multi-scale point of view, and nonlinear models of the manufacturing sector, can provide optimal plans and operational variables for the production goals of the supply chain. In this research, a multi-scale formulation is presented with a production planning model in one to two-year horizon and six-month time periods and production operational scheduling models with six-month horizon to approach the enterprise-wide optimization of a general gas... 

In the upstream part of the natural gas supply chain, the refinery is one of the most complex and energy-intensive sectors that has received little attention. Enterprise-wide optimization, that uses mathematical programming in a centralized and multi-scale point of view, and nonlinear models of the manufacturing sector, can provide optimal plans and operational variables for the production goals of the supply chain. In this research, a multi-scale formulation is presented with a production planning model in one to two-year horizon and six-month time periods and production operational scheduling models with six-month horizon to approach the enterprise-wide optimization of a general gas... 

Helium is a valuable substance that is widely used in industry and medicine because of its unique properties. Due to the increasing demand for helium in the global market, several helium extraction units have been launched in the world in recent years; Nevertheless, there is still a significant gap between projected global helium production capacity and demand. Today, natural gas is known as the main source of helium on the earth. The method of industrial extraction of helium from natural gas is cryogenic. Due to the low temperature of this process, relatively high power consumption is used to extract helium from natural gas. Therefore, the optimization of this process is of great... 

Pre-reduction of some manganese sources (low-grade Venrach and Godar-Sabz ores, high-grade Comilog ore, pellet, pure oxide) by methane gas has been investigated in this research. HSC-Chemistry and FactSage software were used for thermodynamic study of the process. Thermodynamic results indicated that methane may progress to manganese carbide formation, and the reduction process can run autonomously involving less carbon dioxide emission comparing to common ferromanganese process. Several techniques including XRF, XRD, in-situ XRD, SEM-EDS, and thermogravimetry were used in sample characterization and experiments. In addition to the thermal decomposition reactions which were affected by... 

Iran has the second largest natural gas resources in the world and these rich resources provide Iran with good potential for exporting natural gas but so far this potential has not been used well. In contrast, India is a major importer of these energy carriers due to high energy consumption and low level of energy production, especially oil and natural gas production, and continues to increase its imports so that its natural gas imports in 2018 equals 30 billion cubic meters, the IEA expects to reach 85 billion cubic meters by 2040. So the two countries can complement each other in the field of natural gas, such as crude oil and have close relations.In this study, using AHP, Iran's gas...