Natural Gas Liquefaction Research Articles

Energy and exergy analyses of dual refrigerant system for liquefaction of natural gas

Present study proceeds thermodynamic modelling, and analysis of dual refrigerant system for liquefaction of natural gas (LNG) that is one of the most important technologies in producing LNG. Using energy equations pressure, quality, enthalpy, entropy of natural gas and two refrigerants, i.e., methane and propane are specified. The effects of different cycle variables on the thermodynamic performance especially the coefficient of performance (COP) is studied. Using the second law of thermodynamic for the system components, the exergy destruction rates has been found. The exergy analysis results show that heat exchanger I (HX I), heat exchanger II (HX II) and turbine have the highest exergy destruction rate. Furthermore, results indicate that the total exergy destruction rate of studied cycle for generation of 1 kg/s LNG is 2,996 kW. Moreover, energy and exergy analysis show that important parameters such as propane mass flow rate has different effects on the COP and exergy destruction rate.

Energy and exergy analyses of dual refrigerant system for liquefaction of natural gas

Present study proceeds thermodynamic modelling, and analysis of dual refrigerant system for liquefaction of natural gas (LNG) that is one of the most important technologies in producing LNG. Using energy equations pressure, quality, enthalpy, entropy of natural gas and two refrigerants, i.e., methane and propane are specified. The effects of different cycle variables on the thermodynamic performance especially the coefficient of performance (COP) is studied. Using the second law of thermodynamic for the system components, the exergy destruction rates has been found. The exergy analysis results show that heat exchanger I (HX I), heat exchanger II (HX II) and turbine have the highest exergy destruction rate. Furthermore, results indicate that the total exergy destruction rate of studied cycle for generation of 1 kg/s LNG is 2,996 kW. Moreover, energy and exergy analysis show that important parameters such as propane mass flow rate has different effects on the COP and exergy destruction rate.

Внедрение новых технологических решений в циклы внешнего охлаждения процессов извлечения гелия и ожижения природного газа

Внедрение новых технологических решений в циклы внешнего охлаждения процессов извлечения гелия и ожижения природного газа

РОЗРОБКА МАТЕМАТИЧНОЇ МОДЕЛІ КОМПРЕСОРНОЇ УСТАНОВКИ ДЛЯ ЗРІДЖЕННЯ ПРИРОДНОГО ГАЗУ

First of all, such a topic as compressors for liquefaction of natural gas is unfortunately not very well studied. Therefore, this publication will present a detailed study of this object. First of all, the object itself will be considered, what it consists of, what its properties are, how natural gas liquefaction processes take place in it. So first you need to fully study the object itself, and only then proceed to build its mathematical model, which in the future can be used for more detailed analysis, first theoretically and then for practical purposes. This will achieve great results in the construction of an automatic control system for the compressor for liquefaction of natural gas. So, first the object itself will be studied, and only then, based on the acquired knowledge, we will build a mathematical model that will be needed in the future to develop an automatic control system. Of course, if you do not fully study all the properties of the object, such as the physical processes that take place there and the properties of the compressor. And having already put together all the available information, we can have a complete picture of this object. And from this information that has been collected, we can finally move on to the development of a more detailed mathematical model, which will be, albeit simplified, but still close to reality. Only then, already having this mathematical model, you can move on to a more detailed study in theory. And after conducting theoretical research, it is possible to check all the results of the study on a mathematical model, which will help to understand whether they are effective. Because it is more profitable to check theoretical information on a mathematical model than to do it on a real object. This can be costly, and in the case of an installation such as a natural gas liquefaction compressor, it is very expensive. And therefore this mathematical model will be appropriate. This model can be used in a more detailed study of this object because at the moment there is no holistic picture for the dagono object. It will also be possible to apply this model to find the necessary laws of regulation which will help to increase productivity of the compressor installation for liquefaction of natural gas. And this model will help to solve this question and to establish full-fledged work on studying of the given compressor installation.

LNG Transport and Management at South China Sea

As China’s research on LNG maritime transport is still in its infancy, there are few papers in relevant areas. Based on the description of the oil and gas contained in the South China Sea and the geographical location of the oil, the paper compares the natural gas liquefaction with nature, compares the three modes of natural gas transportation, and describes the influencing factors of LNG marine transportation.Secondly, Hainan Province was used as a case of transportation terminal to conduct market analysis and economic evaluation. Finally, considering of the unique resource background and geographical location of the South China Sea, suggestions are made to use effective, clean and comparative cheap energy.

Theoretical comparison of the operation efficiency of two types of magnetic refrigerators working bodiesfor natural gas liquefaction

Theoretical comparison of the operation efficiency of two types of magnetic refrigerators working bodiesfor natural gas liquefaction

The process of production of liquefied methane - the component of rocket propellant

The use of new fuel components, such as LNG or liquefied methane, in rocket-space, aviation and other special-purpose engineering is promising. On the basis of these fuel components it is possible to provide a number of technical and tactical parameters of aircrafts, which are not achievable when using standard fuels. Considered were the cryogenic systems developed by PJSC "Cryogenmash" for natural gas liquefaction with liquid methane recovery by the method of low-temperature condensation, stage separation and rectification. The second method allows to reduce the content of not only low boiling but also high boiling liquids in methane liquefied.

Cultural Resources Survey of Portions of the Rio Bravo LNG Pipeline on Port of Brownsville Lands, Cameron County, Texas

On behalf of Ecology and Environment, Inc. (E & E), Rio Grande LNG, LLC, and Rio Bravo Pipeline Company, LLC (RB Pipeline), SWCA Environmental Consultants (SWCA) conducted cultural resources surveys of portions of the Rio Bravo Pipeline on lands owned or controlled by the Port of Brownsville in Cameron County, Texas. Rio Grande LNG, LLC proposes to construct a natural gas liquefaction facility and liquefied natural gas (LNG) export terminal (Terminal) in Cameron County, Texas, along the north embankment of the Brownsville Ship Channel. In concert with the Terminal, RB Pipeline proposes to construct an associated pipeline system (Pipeline System/Project) within Cameron, Willacy, Kenedy, Kleberg, and Jim Wells Counties, Texas to allow for interconnection with a network of existing pipelines that traverse the northern end of Kleberg County and Jim Wells County. The proposed Pipeline System/Project will collect and transport natural gas to the Terminal site. In compliance with the Federal Energy Regulatory Commission and U.S. Army Corps of Engineers permitting requirements and oversight, SWCA conducted cultural resources investigations in compliance with Section 106 of the National Historic Preservation Act (NHPA) (54 U.S.C. 306108) and its implementing regulations in 36 Code of Federal Regulations 800. Although the entire Project is subject to compliance with Section 106 of the NHPA, this stand-alone report specifically addresses portions of the alignment that will be located on lands owned by the Port of Brownsville (Port). Since the Port is a political subdivision of the state, investigations were conducted in compliance with the Antiquities Code of Texas (ACT) under ACT Permit No. 8588 administered by the Texas Historical Commission (THC). The data in this report is also presented in Addendum IV (Carpenter et al., 2020) to the final report (Nielsen et al., 2016) of the overall investigations. The investigations covered 0.58 mile (0.93 kilometers [km]) of proposed pipeline corridor within a 200-foot-wide (60.96-meter [m]-wide) pipeline survey corridor, and 0.31 mile (0.50 km) of proposed access roads within a 50-foot-wide (15.24-m-wide) access roads survey corridor, for a Project Area total of approximately 15.8 acres within Port property. The cultural resources investigations included a background and historical map review, and an intensive pedestrian survey with subsurface testing. The background review identified nine previously conducted archaeological surveys within a 1-mile radius of the Project Area, three of which intersect the current Project Area. The background review identified no previously recorded archaeological sites within the Project Area; however, seven archaeological sites are within a 1-mile radius none of which are immediately adjacent (within 300 feet [91.44 m]) to the Project Area. In addition, a review of historical maps determined that there are no historic-age structures or features mapped within or immediately adjacent to the Project Area. SWCA archaeologists conducted the cultural resources intensive pedestrian survey on October 22, 2018. The investigation revealed an extensively disturbed setting due to historic & modern development in the area mainly associated with the Port. SWCA archaeologists excavated a total of nine shovel tests within the Project Area all negative for cultural materials. No cultural materials or features or historic-age structures were identified within the Project Area during the field survey. In accordance with the ACT and Section 106 of the NHPA, SWCA has made a reasonable and good faith effort to identify cultural resources within the Project Area of Potential Effects (APE). No cultural resources were identified within the Project Area during the current investigations. Accordingly, no further investigation is recommended for the assessed sections of the Project Area. The THC concurred with these findings and recommendations on January 14, 2020. No artifacts were recovered; documentation will be curated at the Texas Archeological Research Laboratory of The University of Texas at Austin.

A novel integrated hydrogen and natural gas liquefaction process using two multistage mixed refrigerant refrigeration systems

The development and analysis of combined hydrogen and natural gas liquefaction process are reported. Two refrigeration cycles using mixed refrigerants (MRs) are employed. The developed process is capable of generating 290 tons hydrogen and 296 tons liquid natural gas on daily basis. The first refrigeration cycle of the introduced process liquefies 3.5 kg·s−1 normal gaseous hydrogen and 3.5 kg·s−1 normal natural gas at room temperature and 21 bar to −195°C with the consumed power of 0.643 kWh/kgLH2,kgLNG. The second refrigeration cycle cools down the hydrogen and natural gas to −253°C with the consumed power of 1.662 kWh/kgLH2,kgLNG, leading to a lower total consumed power than that of the identical liquefaction processes. The use of novel and appropriately mixed refrigerants based on the configuration, and the thermal design of expanders and heat exchangers fora wide range of temperatures are the innovations of the process. Additionally, the refrigerant compositions of refrigeration cycles are novel. The energy analysis indicated that the coefficient of performance (COP) for the developed process is 0.2442, which is notably high compared with the COP of other identical processes (typically less than 0.1797). The exergy analysis revealed that the overall exergy efficiency of the liquefaction process is 62.54%. Highlight edited A novel integrated hydrogen and natural gas liquefaction process is introduced. The process can generate 290 tons hydrogen and 296 tons liquid natural gas per day. Total power consumptions of the process are 4.165 kWh/kgLH2,kgLNG. Coefficient of performance (COP) for the developed process is 0.2442, which is notably high compared with the COP of other identical processes. Overall exergy efficiency of the liquefaction process is 62.54%.

Technical and economic optimization of expander-based small-scale natural gas liquefaction processes with absorption precooling cycle

The objective of this study is to investigate potential technical and economic performance improvement for expander-based natural gas liquefaction processes in small-scale applications. Four expander-based processes were optimized and compared in this study, including conventional single nitrogen expansion process without (SN) and with ammonia absorption precooling (SNA), and single methane expansion process without (SM) and with ammonia absorption precooling (SMA). A two-phase expander is utilized in the methane expansion process to enable liquid generation at the expander outlet. The optimization was done with two objective functions: minimization of specific energy consumption and minimization of production cost. The energy and cost analyses were performed for the four processes by comparing optimization results. Lastly, exergy losses in the main equipment were analyzed. The results show that the ammonia precooling cycle reduces energy consumption and production cost by 26–35% and 13–17%, respectively. The single methane process with precooling is the most promising process, which has 28–48% lower energy consumption and 13–43% lower production cost compared to those of the other three processes. Results also indicate that the best techno-economic performance is obtained with objective of minimizing production cost and not with the commonly used energy-related objective.

Two-phase expander refrigeration cycles with ethane–nitrogen: A cost-efficient alternative LNG processes for offshore applications

Nitrogen expander-based natural gas (NG) liquefaction processes are considered to be the most feasible and economic practices for offshore applications. The nitrogen single expander process is simple owing to its single-phase operation, and it employs high occupational safety and environment-friendly refrigerants. However, this process has low energy efficiency. Recent advancements in expansion devices show the possibility of handling two-phase refrigerant flow in an economical and simple manner. Accordingly, this paper proposes two-phase expansion using an innovative binary mixed refrigerant (MR) composed of ethane and nitrogen (C2N). Furthermore, a propane-precooling refrigeration cycle is also implemented and evaluated to analyze greater potential benefits of ethane–nitrogen refrigerant with two-phase expansion. To assess the technical and commercial feasibility of the proposed liquefaction process, energy, exergy, and economic (3E) analysis is performed. Using the C2N two-phase expander LNG process, 47.83% energy can be saved with 55.25% exergy destruction minimization and 24.12% total annualized costs (TAC) savings as compared to previously published nitrogen single expander process. Whereas, the C3-precooled C2N process gives higher energy savings i.e., 52.45% but low TAC savings i.e., 1.6% as compared to nitrogen single expander LNG process. Considering TAC savings, the C2N process (without propane-precooling) can be a promising candidate for offshore applications.

Gas–liquid dual-expander natural gas liquefaction process with confirmation of biogeography-based energy and cost savings

The use of nitrogen (N2) expander-based liquefaction processes is prevalent in offshore sites for the production of floating liquefied natural gas. It is safe, has simple operability, and has portable design with a small deck space requirement. However, the high operating cost that mainly accounts for the shaft work requirement in the compression units of the refrigeration cycle, is still a major ongoing issue associated with nitrogen expander liquefaction processes. This high operating cost increases the total annualized costs of the N2 expander liquefaction technology, and this ultimately reduces its global competitiveness of the process. Recent developments in expansion devices pave the way toward the handling of gas–liquid (two-phase) refrigerant in an isentropic manner instead of an isenthalpic one. This study presents the propane-nitrogen two-phase dual expander liquefaction process for offshore applications. A bio-inspired strategy named “biogeography” is used to confirm the overall energy savings with minimal total annualized costs. The results show that the proposed liquefaction technology gives 36.6% operating cost savings, and this confirms a 16.5% saving in total annualized costs compared with the conventional nitrogen dual gas-phase expander liquefaction process. This study is an extension of our previous study “Innovative propane-nitrogen two-phase expander refrigeration cycle for energy-efficient and low-global warming potential LNG production”.

Design and thermoeconomic analysis of a multi-effect desalination unit equipped with a cryogenic refrigeration system

In this paper, a hybrid tri-generation system is designed to produce LNG and freshwater simultaneously based on a multi-effect desalination system and analyzed using energy and exergy analyses. For natural gas liquefaction, the initially required cooling of the cycle is supplied by ammonia-water absorption system, and the required intermediate cooling load and liquefaction process are provided by a refrigeration system with mixed fluid. Two alternatives for providing power generation to the system and the required heat for driving the absorption cycle have been considered and compared. The first alternative relies on a natural-gas-fired power plant, while the second is based on steam-solar power plant with dish collectors. The former results in the total energy efficiency of 85.8% (LHV). The highest thermodynamic irreversibilities occur in the heat exchangers (61%), even if they have the highest exergy efficiency compared to the other plant equipment. On the other hand, using solar dish collectors enables to decrease carbon dioxide emissions by 40%, and increases freshwater and LNG production by 95% and 4.7% respectively. The power obtained per kg of LNG produced is about 0.19 kWh, which is less than or equal to the other similar patents. The results of the economic analysis with the annualized cost method of the system show that the products prime cost of both structures 1 and 2 are equal to 0.2580 and 0.1784 US$ per kg of LNG, respectively. A suitable strategy for modelling enhancement of system’s parameters is suggested by expanding of sensitivity analysis on the important parameters of the developed system.

Modeling and simulation of a natural circulation water-tube steam boiler

In the present work, the overall behavior of a steam boiler is investigated using RELAP5/MOD3.2 system code at three different operating loads. Main thermal–hydraulic parameters are analyzed at steady-states corresponding to 60%, 100% and 110% of the boiler nominal load. RELAP5 system code is widely used in the design and safety analysis of nuclear reactor installations as well as for conventional facilities in recent years. The steam boiler studied herein is a water-tube natural circulation type used in a natural gas liquefaction complex for superheated steam production purposes. A complete model of the steam boiler has been developed for the RELAP5 code. This model, that is also suitable for transient simulation, has been used for the reconstruction of three steady-state tests in order to assess the steam boiler safety features during the operation. The model includes all parts that can eventually influence the safety of the steam boiler particularly the control and regulation system. A qualification process has been undertaken in the aim to verify the capability of the model to reproduce the main parameters of the steam boiler. This process revealed that RELAP5 system code results matches significantly the experimental data of the steam boiler. Finally, it should be mentioned that the results obtained so far are very encouraging for studying the general behavior of the steam boiler in transient operating conditions, as well as for evaluating its safety under hypothetical scenarios. This step will be undertaken in the near future and will allow the check of the code capability to simulate thermal–hydraulic phenomena occurring in the steam boiler during transient operation.

Development of natural gas liquefaction processes using mixed refrigerants: a review of featured process configurations and performance

It is preferable to transport or store natural gas (NG) in a liquid state, as liquefied natural gas (LNG). In recent decades, a variety of natural gas liquefaction processes (NGLPs) using mixed refrigerants (MRs) with different configurations have been developed, which have greatly enriched the family of NGLPs. In this review, we introduce the configurations of featured commercial processes or patented designs chronologically in each category based on a modified classification framework. The corresponding refrigerant combinations and operating parameters such as operating pressures, the refrigeration temperature in each stage, and the number of evaporating pressure levels are also discussed. Specific power consumption (SPC) was considered as the major performance indicator. This review aims to clarify the development of NGLPs using MRs (MR-NGLPs) from a configurative perspective, and to provide a reference for the future improvement of their thermodynamic performance.

Experimental and numerical simulation study on the offshore adaptability of spiral wound heat exchanger in LNG-FPSO DMR natural gas liquefaction process

For studying the performance of spiral wound heat exchangers (SWHEs) applied in the LNG-FPSO (LNG Floating Production Storage and Offloading unit) dual mixed refrigerant (DMR) liquefaction process, an experimental device and a numerical simulation model of DMR liquefaction process are established. Based on the experimental results and the REFPROP software, the effects of sloshing on the performance of SWHE are selected as the disturbances to test the responses of the DMR liquefaction process. The results show that the sloshing-induced reduction of SWHE heat transfer performance is within 50% for all sloshing cases. The decrease of specific power consumption of DMR liquefaction process is within 13%, when the SWHE is under sloshing angles from 3° to 9° and sloshing periods from 6 s to 30 s.

Thermodynamic analysis of natural gas liquefaction process with propane pre-cooled mixed refrigerant process (C3MR)

Liquefaction processes plays an important role for transmission of natural gas in long distances. Production of liquefied natural gas (LNG) is classified as an energy consuming process. LNG is a complicated thermodynamics process and the thermodynamics analysis for the key points of the system seems necessary. The goal of this study is to enhance the overall performance and heat recovery from outlet streams of LNG process by changing the process thermodynamics variables. Simulation and sensitivity analysis for two objective functions; specific energy and compressor power consumption were done by Aspen HYSYS process simulator. The investigated variables in this study are four pressure levels, inner and outlet pressures of main compressor and the flow rate of propane in precooling cycle. By considering the process limitations, the possible range for each variable was obtained and then sensitivity analysis was done for each parameter. The obtained results show more improvement on objective functions compared to the other investigations; specific energy for this process was obtained 845 kJ/kg, which shows 30% improvement compared to initial model and the total energy consumption reached to 62.7 MW while it was 71 MW for initial model.

Numerical investigation of plume dispersion characteristics for various ambient flow velocities

Floating LNG bunkering offshore terminal (FLBT) has been adopted as a floating unit by the marine industry equipped with the natural gas liquefaction plant on the ship’s deck with the practical interest in controlling the plume emission discharged from the ship. The downwash of emitted plumes has adverse consequences on the ship’s engine intake and ventilation system followed by the interference of the smoke with helicopter operations. Owing to this fact, understanding of the plume behavior is considered to be so significant in the aspect of ship design and thereby, flow visualization techniques assist to study the plume path ensuring the safety of the personnel and functioning system. The unignited flare gas emitted from the tower invites heat transfer due to the temperature difference between the atmospheric wind and the ship’s exhaust, which follows the examination of mixing enhancement of fluid mediums as well as the mitigation of plume concentration depending upon wind speeds. The parametric study is intended to investigate the plume dispersion pattern around a ship based on the flare motion and bending angle for light and strong wind speeds. It is observed that the plume gas rises higher and disperses over the larger area with wider streamline separation due to the effect of buoyancy for light wind speeds. On the other hand, the motion of flare gas is found to be narrow for strong winds restricting vertical movements due to dominant inertial forces than gravity pull. Thus, the current numerical investigation facilitates in understanding the configuration and plume distribution by the variation in streamline behavior with contours plots. In this work, the calculated results are analyzed systematically in pretty realistic conditions and simple measures are obtained, which will be applied to the preliminary design of plume stack depending on the ship’s deck arrangement.

Special Issue: Modeling and Simulation of Energy Systems

This editorial provides a brief overview of the Special Issue “Modeling and Simulation of Energy Systems.” This Special Issue contains 21 research articles describing some of the latest advances in energy systems engineering that use modeling and simulation as a key part of the problem-solving methodology. Although the specific computer tools and software chosen for the job are quite variable, the overall objectives are the same—mathematical models of energy systems are used to describe real phenomena and answer important questions that, due to the hugeness or complexity of the systems of interest, cannot be answered experimentally on the lab bench. The topics explored relate to the conceptual process design of new energy systems and energy networks, the design and operation of controllers for improved energy systems performance or safety, and finding optimal operating strategies for complex systems given highly variable and dynamic environments. Application areas include electric power generation, natural gas liquefaction or transportation, energy conversion and management, energy storage, refinery applications, heat and refrigeration cycles, carbon dioxide capture, and many others. The case studies discussed within this issue mostly range from the large industrial (chemical plant) scale to the regional/global supply chain scale.

Oilfield Flares Provide a Glaring Reminder of the Drive To Produce More Oil

Natural gas flared in just two major US shale plays exceeded the amount of gas consumed last year in Colombia and Israel. The prolific waste from the Permian and the Bakken (Figs. 1 and 2) is a side effect of rising oil production in plays where gas growth is so strong pipeline construction cannot keep up. Flaring is a glaring reminder of the realities of the never-ending rush to drill that is driving down the cost of oil and gas around the globe. These oil-producing wells also produce more gas than processing plants and pipelines can move to market. Pipelines and refineries have recognized that ultralight oil in the Permian is fundamentally different from West Texas Intermediate (WTI), with a make-up that puts it somewhere between oil and gas•liquids. As those wells age, oil production falls as the output shifts to gas. And the cost of sustaining production for the vast majority of producers has consistently exceeded the cash generated by these wells (Fig.• 3). The gap between capital expenditures and revenues was “a staggering $4.7•billion” during the first quarter of 2019, according to a study by Alisa Lukash, a senior analyst on Rystad Energy’s North American shale team, who described it as a “tremendous overspend.” Both the US Energy Information Administration (EIA) and Rystad have raised outlooks that already predicted strong US oil growth. Flaring growth and overspending have accompanied a rebound in growth in the Permian and Bakken, which are the flaring leaders by far in the US. More than half of the total comes from the Permian, which has surpassed the Bakken by more than tripling the volume of gas burned per day since early 2017. The severity of the problem, though, is more acute in the Bakken. While Rystad said about 5% of the Permian gas is flared, in the Bakken, 19% of the gas is flared, according to the oil and gas division of the North Dakota Industrial Commission. The Permian produces far more gas but has the advantage of being close to growing markets for it—chemical plants, export pipelines to Mexico, and natural gas liquefaction facilities—while North Dakota is a distant option for Midwestern markets well supplied by other plays. Limited pipeline capacity means those shippers without contracts ensuring they can move their gas are paid little or less than nothing—prices at Waha gas hub in west Texas repeatedly sank into negative territory over the winter, and pipeline shortages will linger until a big new pipeline goes into service. Oil pipeline construction also has lagged supply growth in the Bakken. Trains and trucks can ship oil, but that is a costly option. North Dakota oil regulators reported that Bakken prices hovered around $50/bbl early this year when the benchmark US oil grade was about $10/bbl higher.