Natural Gas Liquefaction Research Articles (Page 1)

A Thermo-economic optimization of dual multicomponent refrigerant Cycles: Minimizing operational expenditure (OPEX) in natural gas liquefaction

Analysis of the influence of mixed refrigerant pressure on performance of natural gas liquefaction process from a new view of interactions among process parameters

Summary In this study, we propose a systematic method for optimizing the scanning strategy of pan-tilt tunable diode laser absorption spectroscopy (TDLAS) detection devices to enhance inspection efficiency. Gas leakage scenarios are identified and then simulated using computational fluid dynamics (CFD) to predict concentration distributions across the monitoring area. A multicondition data extraction model is developed to process and retrieve the CFD data. The optimization goal is framed as the minimum cumulative detection time considering scenario probabilities (MCDT-SP), with an enhanced particle swarm optimization (PSO) solution algorithm used to simultaneously optimize scanning points and sampling durations. The approach is demonstrated through a case study at a natural gas liquefaction plant, where results show significant improvements in detection efficiency, including reduced scanning points and faster leak detection. This method holds significant potential for application in industrial scenarios utilizing TDLAS technology for detection and is expected to provide actionable insights and effective support for the development of inspection strategies in the oil and gas industry.

A multi-criteria evaluation on the selected liquefied natural gas (LNG) liquefaction process designs integrating process safety and economic aspects

This research explores supersonic cyclonic separation for natural gas liquefaction (LNG). A 3D computational model was developed using the Eulerian–Eulerian two-fluid framework to simulate spontaneous gas condensation. The model tracks droplet formation/growth mechanisms and employs Reynolds stress modeling (RSM) for turbulence, implemented in Fluent via user-defined functions (UDFs). Validated against experimental data, it accurately predicted condensation onset and shock wave behavior. A prototype separator designed for a natural gas peak-shaving station demonstrated lower temperatures than throttling valves but modest liquefaction efficiency (4.28% at 5 MPa inlet pressure). Two enhancement strategies were tested: (1) injecting submicron LNG condensation nuclei (radius < 1 × 10−9 m) significantly boosted liquefaction by reducing nucleation energy barriers and suppressing condensation shocks; (2) a multi-stage configuration increased total liquefaction by 156% versus single-stage operation. These findings highlight the technology’s potential for energy-efficient gas processing.

Design and theoretical analysis of a high-performance heat-driven thermoacoustic cryocooler for natural gas liquefaction

This work investigates the effect of imbalance and bearing wear on the vibration of rotating shafts at a southern Iraqi natural gas liquefaction plant. This experimental study examines the impact of wear on couplings and uneven weight on the vibration of a two-stage gas turbine’s shaft, taking measurements during operation. The experimental procedure involves the use of proximity probes and the ADRE-408 Bentley Nevada system to measure vibrations along the X and Y axes. The study focuses on a two-stage gas turbine supported by four journal bearings and analyses the effects of coupling imbalance and erosion. The results show that adding 10 g and 20 g weights at 0° and 30° anticlockwise considerably increases the vibration amplitude, from 22.46 µm at 113.75 Hz to 24.35 µm at 117.5 Hz. Replacing worn couplings and bearings led to system stabilisation, vibration reductions, and a shift in critical frequencies. The data confirm that mass loss and bearing wear greatly affect the dynamics of rotating machinery. These findings emphasise the importance of predictive maintenance and diagnostic monitoring to prevent mechanical failures and maintain system stability.

The increasing global demand for natural gas as a cleaner energy alternative has intensified the need for more energy-efficient liquefaction technologies. One of the key components in natural gas liquefaction is the refrigeration cycle, where the choice of refrigerant significantly influences system performance. Propane is widely used due to its favorable thermodynamic properties. However, there is growing interest in optimizing its performance through refrigerant blending. This study investigates the impact of different propane-based refrigerant mixtures, namely propane-NH₃, Propane-SO₂, and propane-CO₂ on the coefficient of performance (COP) in a natural gas liquefaction cooling cycle. Simulation results at two operating temperatures (-15.11°C and -20°C) demonstrate that refrigerant composition plays a crucial role in determining system efficiency. At -15.11°C, pure propane exhibited a COP of 2.79, while mixtures with NH₃ and SO₂ significantly improved performance, achieving peak COPs of 6.25 and 6.42, respectively, at a 1:9 mixing ratio. Similar trends were observed at -20°C, where the highest COP values for propane-NH₃ and propane-SO₂ mixtures were 5.79 and 5.96, respectively. In contrast, the propane-CO₂ mixture consistently yielded the lowest COP values, indicating inferior energy efficiency. These findings suggest that incorporating NH₃ or SO₂ into propane-based refrigeration cycles can substantially enhance the energy performance of natural gas liquefaction processes, whereas propane-CO₂ blends may increase energy consumption and operational costs.

Multi-effect distillation with novel liquid vapor ejector utilizing the waste heat from intercoolers of a single mixed refrigerant cycle for natural gas liquefaction

Precise calculations of thermodynamic properties are essential for enhancing the efficiency of natural gas liquefaction and regasification processes. These calculations play a vital role in understanding phase equilibria, which is critical for ensuring optimal performance in both the liquefaction of natural gas, transforming it into a liquid state for easier storage and transport and the regasification process, which converts it back into a gaseous state for use. By accurately determining properties such as temperature, pressure, and chemical potential, engineers can design more effective systems that maximize energy efficiency and reduce operational costs, ultimately leading to improved overall performance in natural gas processing. This study aims to improve predictive accuracy by utilizing a set of 16 fundamental equations that describe the behavior of real gases. These equations take into account various factors such as pressure, temperature, and volume, allowing for a more precise representation of gas behavior under different conditions. By employing these established equations, the study enhances the reliability of predictions related to gas dynamics, making it possible to achieve more accurate modeling in practical applications and scientific research. The analysis focuses on the variations from optimal conditions in high-pressure cryogenic environments. It employs a range of theoretical tools, including virial coefficients to understand interactions among particles, as well as Helmholtz and Gibbs energies to assess the system's thermodynamic stability and equilibrium. Furthermore, the study integrates correlations of heat capacity to evaluate the thermal properties and behavior of materials under extreme conditions. The study further enhances the understanding of LNG pipeline flow modeling by incorporating detailed calculations of both the speed of sound and the bulk modulus. This integration allows for more accurate simulations of flow dynamics, enabling better design and optimization of pipeline systems to ensure safety and efficiency during transport. The research focuses on enhancing phase equilibrium modeling, essential in optimizing energy consumption within liquefied natural gas (LNG) processes. The study aims to minimize energy losses during the production and transportation of LNG. Furthermore, this approach improves the design of LNG processes by increasing its overall efficiency, contributing to more sustainable practices in the industry.

The increasing demand for energy-efficient and environmentally friendly liquefied natural gas (LNG) production has led to the exploration of alternative refrigerants in cascade liquefaction systems. This study presents a comparative thermodynamic analysis of inorganic refrigerants in cascade liquefied natural gas (LNG) liquefaction systems, focusing on performance metrics. The research aims to evaluate the exergy losses, coefficient of performance (COP), energy requirements, and overall thermodynamic efficiency of various refrigerants, including Argon, Krypton, Xenon, Nitrogen, and the conventional C3MR (Propane Mixed Refrigerant). Results reveal significant variations in refrigerant performance. C3MR demonstrates the highest COP (4.25) but exhibits moderate exergy efficiency (63%) and high energy losses in compressors. Noble gases show contrasting trends: argon achieves exceptional exergy efficiency (83%) but poor COP (1.38), while xenon has low exergy efficiency (36%) but a competitive COP (2.99). Nitrogen incurs catastrophic exergy losses during depressurization (345,439 kJ/hr), highlighting operational challenges. The study underscores the need for component-specific refrigerant optimization and suggests hybrid systems combining C3MR’s heat transfer advantages with argon’s exergy efficiency. These findings advance LNG liquefaction technology by providing a nuanced framework for balancing thermodynamic performance, environmental impact, and operational feasibility

As the demand for Liquefied Natural Gas (LNG) continues to rise, the need for efficient and environmentally friendly refrigeration technologies has become more critical. This study presents a comprehensive review of inorganic refrigerants used in Liquefied Natural Gas (LNG) liquefaction cycles, concentrating on their thermodynamic performance and environmental effects. Using a thorough literature study, important refrigerants such as nitrogen, argon, krypton, xenon, and ammonia were examined in terms of efficiency, energy consumption, and sustainability. The findings show that inorganic refrigerants can improve energy efficiency by lowering power consumption and increasing exergy performance. Nitrogen was found to require the least amount of energy, whereas ammonia significantly increased the coefficient of performance (COP) in mixed refrigerant applications. Krypton and xenon both demonstrated great exergy efficiency, making them attractive candidates for future LNG operations. While these refrigerants have a lesser environmental effect than standard hydrocarbons, more advances are needed. The study recommends optimizing hybrid refrigerant systems, including renewable energy, and improving safety measures. Advancing these strategies can make LNG production more sustainable, reducing its carbon footprint while maintaining efficiency.

The liquefied natural gas (LNG) floating production storage and offloading (FPSO) unit is a new type of floating production device developed for the exploitation, pretreatment, liquefaction, and storage of offshore natural gas. In this study, the shell side structure of the spiral-wound heat exchanger is analyzed, and the effects of varying the Reynolds number (Re), tube outer diameter, and number of distributors on the thickness of the shell-side liquid film are investigated. The results show that as the fluid flows down from the distributor, it hits the upper wall of the pipeline and diffuses evenly to both sides, before converging in between the two distributors. In the axial direction, the thickness of the liquid film increases first, reaches the highest at the peak, then decreases, reaches the lowest at the trough, and then increases again, forming a secondary peak at the drop. The thickness of the liquid film changes periodically, and the period is the distance between the two distributors. The thickness of the circumferential liquid film is negatively correlated with the circumferential angle, α. Moreover, the liquid film is thinnest at α = 120°, and is positively correlated with both the liquid mass flow rate and the outer diameter of the tube. The most uniform liquid film thickness is obtained when Re = 1500, the tube outer diameter is 12 mm, and the number of distributors is 6. The results from this study can guide the design of spiral-wound heat exchangers and facilitate their safe and efficient operation in natural gas liquefaction processes.

Accurate prediction of in-channel condensation heat transfer performance for natural gas liquefaction based on machine learning models and correlations

Mounting delays for natural gas liquefaction projects in the US and around the world not only place fresh strains on the pocketbooks of the operating companies but have had the knock-on effect of causing a vessel glut. Newbuild LNG carrier deliveries have been outpacing the new liquefaction facilities built to support them. Facilities delays come in various forms, whether its materials, lining up enough contracts to make a final investment decision, or in the case of the US, playing catch-up after the Biden administration’s year-long pause on issuing new permits for LNG projects. The current administration lifted the pause in late January. Permitting across the board has become a bit of a nightmare to hear some operators tell it. Getting the paper to conduct the simplest project can take months and at a much greater cost than previously experienced. Perhaps no example is more telling of this new world order than the one given by Williams President and CEO Alan Armstrong at CERAWeek by S&P Global in Houston in March. “A project we’re working on right now, the permitting cost side of the project, and this is if everything goes well—the permitting cost is twice as much as we’re spending on pipe,” he said. “So, when people talk about tariffs, we’d be glad to pay the 25% tariff as long as we can get our permits done. There is so much value to be had for our country in getting our permitting lined out in a way that we don’t wind up in courts and we don’t wind up with the risk dollars. Frankly, it’s not just the time, it’s not just the cost of that. It’s the risk associated with having a project stop after you’ve spent hundreds of millions of dollars (on it).” While operators continue to navigate the uncertain permitting waters, Chinese and other Far East shipyards are churning out new LNG carriers. The current building cycle can be traced back to the beginning of the Russia/Ukraine war. When Russian natural gas supply was cut off, the need for new supplies to flow into certain areas in Europe became urgent. The quickest answer was to bring LNG into the region. The new market demanded new infrastructure and that included carriers to move the fuel from suppliers to the new market. “You had a lot of ships being used for (LNG) storage in Europe when the war first started,” explained Josie Mills, senior analyst at Enverus. “With less ships being used for storage; those have also moved back on the market. So, not only are you having the ships that have been constructed coming online, but you’re also seeing those come back online too.” As vessel deliveries mounted without cargoes to transport, the additional units began placing downward pressure on charter rates—sending them to historic lows. In some markets, the rates went negative for several days.

Recent research in the liquefied natural gas (LNG) industry has concentrated on reducing specific power consumption (SPC) during production, which helps to lower operating costs and decrease the carbon footprint. Although reducing the SPC offers benefits, it can complicate the system and increase investment costs. This review investigates the thermodynamic parameters of various natural gas (NG) liquefaction technologies. It examines the cryogenic NG processes, including integrating NG liquid recovery plants, nitrogen rejection cycles, helium recovery units, and LNG facilities. It explores various approaches to improve hybrid NG liquefaction performance, including the application of optimization algorithms, mixed refrigerant units, absorption refrigeration cycles, diffusion–absorption refrigeration systems, auto-cascade absorption refrigeration processes, thermoelectric generator plants, liquid air cold recovery units, ejector refrigeration cycles, and the integration of renewable energy sources and waste heat. The review evaluates the economic aspects of hybrid LNG systems, focusing on specific capital costs, LNG pricing, and capacity. LNG capital cost estimates from academic sources (173.2–1184 USD/TPA) are lower than those in technical reports (486.7–3839 USD/TPA). LNG prices in research studies (0.2–0.45 USD/kg, 2024) are lower than in technical reports (0.3–0.7 USD/kg), based on 2024 data. Also, this review investigates LNG accidents in detail and provides valuable insights into safety protocols, risk management strategies, and the overall resilience of LNG operations in the face of potential hazards. A detailed evaluation of LNG plants built in recent years is provided, focusing on technological advancements, operational efficiency, and safety measures. Moreover, this study investigates LNG ports in the United States, examining their infrastructures, regulatory compliance, and strategic role in the global LNG supply chain. In addition, it outlines LNG’s current status and future outlook, focusing on key industry trends. Finally, it presents a market share analysis that examines LNG distribution by export, import, re-loading, and receiving markets.

Spiral wound heat exchangers are the core equipment for natural gas liquefaction. Their heat transfer performance significantly affects the liquefaction process. This research investigates how varying sloshing amplitudes and periods affect the heat transfer and pressure drop characteristics of a spiral-wound heat exchanger subjected to yawing, heaving, and inclination. The UA value (where U represents the heat transfer coefficient in W·(m2·K)-1 and A denotes the heat exchange area in m2) exhibits an initial increase followed by a decrease as the yawing sloshing amplitude increases. The UA value at a yaw of 3° is 6.23% higher than the static value, while the UA value at a yaw of 9° is 19.53% lower. The fluctuation in the UA value decreases with an increase in the yawing sloshing period. When the sloshing period is 6 s, the UA value decreases by 16.46% compared to the static value. In contrast, when the sloshing period is 20 s, the UA value slowly increases by 4.19%. The UA value decreases with an increase in the amplitude of heaving sloshing. When the inclination starts, the UA value suddenly increases and then gradually decreases with time. Based on these observations, a mathematical model of heat transfer under yawing conditions is established. The heat transfer performance of spiral-wound heat exchanger under sloshing conditions is systematically studied, and the influence mechanism of sloshing on heat transfer efficiency of heat exchanger is revealed, which provides a new research perspective and experimental data for related fields.

Energy conservation and techno-environmental analysis in natural gas liquefaction with single and dual-mixed refrigerants: A comparison

Investigation of microscopic mechanisms for carbon dioxide homogeneous crystallization during pressurized liquefaction of natural gas

Applying printed circuit heat exchangers (PCHEs) in small-scale natural gas liquefaction refineries can be a practical innovation for the expansion of such liquefaction units in industrial zones as well as areas far from the national natural gas network. After an overview of the state of the art related to the small-scale LNG refineries, the lack of applying PCHEs was observed. The gravitational and centrifugal buoyancy for a horizontal C-shaped channel of a PCHE have been studied numerically. OpenFOAM (version v1606+) software was used to model the cooling process. The most common component of natural gas is methane, so methane has been considered as the heat transfer fluid in this study. The dome-shaped distribution of the Grashof number reveals that mixed convection heat transfer becomes more active around the pseudo-critical point. Greater flattening of the C-shaped zigzags can cause an average increase of 49% for the centrifugal Grashof number in the supercritical process and a 30.9% increase for the gravitational Grashof number in the trans-critical process. As the zigzags become sharper, an increase of 29.12% in the Nusselt number for the supercritical process and 30.81% for the trans-critical process will be reached and the total entropy generation experiences a decrease of about 41.37% for the supercritical process and 32.03% for the trans-critical process. The proximity of the synergy number to one radian indicates that geometrical changes in the channel enhance heat transfer. The results can help to improve and develop the design of PCHEs for natural gas liquefaction process in small-scale refineries.