LNG Carrier Research Articles

LNG Type C, Cylindrical Weight Design Limitation Based on Shipbuiding Facilities

Supporting climate change mitigation and sustainable energy due to its ability to reduce CO2, Liquefied Natural Gas (LNG) considered as promising alternative fuel. In a particular small market with LNG demand between 2,500 m3 to 7,500 m3, utilization of LNG type-C, cylindrical tanks are compatible to use in small-scale LNG carrier. In order to overcome these challenges, Indonesian industry need to design the tank’s volume and weight requirements.while also taking into account the capabilities of the shipbuilding facilities. The weight of the tank, which comprises the weight of the outer tank and dished end, are the decision variable in the approach for weight estimation analysis, which carried by using using extrapolation to search optimum diameter and length of the tank The objective function is maximization of the tank capacity. The capability of the lifting equipment in the shipyard is the limitation used in this paper. This research data is based on the shipyard capability of PT. PAL Indonesia, PT. Dok dan Perkapalan Kodja Bahari (Persero), PT. Industri Kapal Indonesia, and PT. Batamec Shipyard. Result obtained that maximum volume of 5,663.369 m3 LNG type C, weight about 450.671 tons with maximum crane lifting capacity in shipyard are 500 tons

Research on the navigational risk of liquefied natural gas carriers in an inland river based on entropy: A cloud evaluation model

Abstract Due to the flammability and explosive nature of liquefied natural gas (LNG), an extremely strict process is followed for the transportation of LNG carriers in China. Particularly, no LNG carriers are operating in inland rivers within the country. Therefore, to ensure the future navigation safety of LNG carriers entering the Yangtze River, the risk sources of LNG carriers' navigation safety must be identified and evaluated. Based on the Delphi and expert experience method, this paper analyses and discusses the navigation risk factors of LNG carriers in the lower reaches of the Yangtze River from four aspects (human, ship, environment and management), identifies 12 risk indicators affecting the navigation of LNG carriers and establishes a risk evaluation index system. Further, an entropy weight fuzzy model is utilized to reduce the influence of subjective judgement on the index weight as well as to conduct a segmented and overall evaluation of LNG navigation risks in the Baimaosha Channel. Finally, the cloud model is applied to validate the consistent feasibility of the entropy weight fuzzy model. The research results indicate that the method provides effective technical support for further study on the navigation security of LNG carriers in inland rivers.

Sloshing Assessment and Development of Small Scale LNG Carrier Containment System

Sloshing Assessment and Development of Small Scale LNG Carrier Containment System

An investigation of the cooling, heating and power systems integration with carbon capture and storage for LNG carriers

ABSTRACT This study investigates the cooling, heating and power (CHP) systems integration with the carbon capture and storage (CCS) for different LNG carriers. Different integration levels of conventional waste heat recovery, boil-off natural gas (BO-NG) reliquefaction, CO2 capture and liquefaction, and ORC systems are modelled and simulated using Aspen HYSYS. Thermoeconomic optimisation is also carried out using Genetic algorithm method. Results demonstrate that using CCS system is more cost-effective than paying European Union carbon tax for LNG carriers. Integrating the BO-NG and CO2 liquefaction cycles could reduce the total life cycle cost of the CCS system up to 17%. Optimised results show that selecting working pressure is very critical for the liquefaction of BO-NG and CO2. CHP system using ORC reduces the energy penalty of the CCS system, however, it increases the total life cycle cost of the system due to its initial cost and relatively low exergy efficiency.

Experimental Study on the Effect of Extreme Waves on a LNG Carrier

This paper presents a comprehensive experimental study on the effect of extreme waves on a LNG carrier. The LNG carrier model was equipped with a variety of sensors to measure motions, green water height on deck as well as local and global loads. Experiments in transient wave packets provided the general performance in waves in terms of response amplitude operators and were accompanied by tests in regular waves with two different wave steepness. These tests allowed detailed insights into the nonlinear behavior of the vertical wave bending moment in steep waves showing that green water on deck can contribute to a decrease of vertical wave bending moment. Afterwards, systematic model tests in irregular waves were performed to provide the basis for statistical analysis. It is shown that the generalized extreme value distribution model is suitable for the estimation of the extreme peak values of motions and loads. Finally, model tests in tailored extreme wave sequences were conducted comparing the results with the statistical analysis. For this purpose, analytical breather solutions of the nonlinear Schrödinger equation were applied to generate tailored extreme waves of certain critical wave lengths in terms of ship response. Besides these design extreme waves, the LGN carrier was also investigated in the model scale reproduction of the real-world Draupner wave. By comparing the motions, vertical wave bending moment, green water column and slamming pressures it is concluded that the breather solutions are a powerful and efficient tool for the generation of design extreme waves of certain critical wave lengths for wave/structure investigations on different subjects.

A methodology for risk assessment of LNG carriers accessing vulnerable port areas

The navigation course of Liquefied Natural Gas (LNG) carriers and fueled ships may cross vulnerable areas where commercial, civil, and industrial assets are present. Despite the effort made by scientific community and authorities, there are no consolidated methodologies addressing the risks arising from the interaction between LNG carriers and fueled ships accessing ports and onshore facilities. This work focuses on the development of a simplified methodology for risk assessment of LNG carriers and fueled ships in port areas able to identify accident scenarios involving the ship course and vulnerable targets. The analysis starts verifying the compliance with respect to the port regulations and the feasibility of the course with respect to the channels. Then, based on standard features of LNG carriers and fueled ships, a set of reference accidental scenarios to be considered during the risk assessment is identified. A specific guidance for the identification of hazards, estimation of frequencies and consequences is provided, finally adopting a customized risk matrix to support decision-making on prevention and mitigation measures. The application of the methodology to a real case study dealing with an important Italian harbor, highlights the capability of the method to support land use planning.

Long-term approach for assessment of sloshing loads in LNG carrier, part II: Grouping method

Assessing the sloshing loads has been a significant issue in designing the cargo containment system (CCS) of a liquefied natural gas carrier (LNGC). The sloshing problem contains numerous physical and technical uncertainties. The long-term approach has been suggested to reduce the possible uncertainties, but it has not been a feasible option owing to the incalculable number of experimental cases. Daewoo Shipbuilding and Marine Engineering Co., Ltd., Hyundai Heavy Industry Co., Ltd., Samsung Heavy Industry Co., Ltd., Korean Register, and Seoul National University conducted extensive sloshing model tests for the 174 K S-LNGC. To consider the long-term approach, Part I describes the differences between short- and long-term approaches based on the guidelines of different classification societies. To address the significant number of experimental conditions required for the long-term approach, a grouping method is investigated (Part II). Although this grouping method is typically used in practical design, it has not been validated, and its applicability is yet to be determined. In Part II, the sea states are classified using 16 different grouping methods. The long-term exceedance probabilities and pressures are obtained individually and then compared with the results obtained from fully considering all sea states. After performing the general sloshing model test of the shipbuilding industry, the sloshing impact pressure of a liquefied natural gas cargo model is measured via 6DoF irregular simulations, where the upper section of the cargo hold structure is considered. Long-term pressures are locally and globally investigated and compared among 16 different sea states and all the sea states. Based on the results, the best grouping method is suggested for the long-term approach.

Long-term approach for assessment of sloshing loads in LNG carrier, Part I: Comparison of Short- and Long-term approaches

To assess the long-term sloshing loads of a liquefied natural gas carrier, Daewoo Shipbuilding and Marine Engineering Co., Ltd., Hyundai Heavy Industry Co., Ltd, Samsung Heavy Industry Co., Ltd. (SHI), Korean Register, and Seoul National University conducted a series of joint industrial experiments using a six-degree-of-freedom irregular sloshing model test. SHI provides a 174 K S-LNGC and its cargo hold information. To consider the numerous test conditions of the long-term approach, the present study focuses on the upper regions of the cargo hold structure, and feasible operating scenarios are assumed. A total of 3870 h at a real scale are simulated based on 387 sailing conditions. Extensive experimental results of sloshing loads are analyzed based on different guidelines suggested by different maritime classification societies. Part I of this study provides an assessment of sloshing loads based on a comparison of short- and long-term approaches distinguished by the guidelines, and the possible reference values are presented. A practical solution for the long-term approach will be discussed in Part II.

Перспективы развития мирового рынка морских перевозок сжиженного природного газа

This article explores the significance of future prospects for the development of maritime transportation of natural gas, which is one of the main sources of energy raw materials. Transportation of gas on sea vessels is expedient and cost-effective only in liquefied form, when the volume of natural gas is reduced by more than 600 times. Liquefied natural gas (LNG or LNG) carriers are called LNG carriers. The purpose of the study is to develop a new mathematical model that will play the role of a methodological basis for forecasting changes in the global volume of LNG shipping. In the course of the study, general scientific methods of system analysis and synthesis, methods of mathematical statistics were used. The article presents the results of the study of trends in the global maritime LNG transportation market development. The author considers the main exporters and importers of LNG, as well as an assessment of the growth in its demand after the decline of the COVID-19 pandemic. The trend in the development of innovative gas liquefaction production capacities, as well as the state of the world LNG fleet and the dynamics of its increase, are analyzed.The development research of this area of maritime transportation has been carried out and the dynamics of the increase in the volume of transported LNG in recent years has been analyzed.

Alternative Ways of LNG Transportation Selection and Risk Management in Perspective of Bangladesh: A Case Study

One of the nations with the densest populations is Bangladesh. The nation's energy use is increasing progressively. One of the greenest forms of energy is LNG. Natural gas, a liquefied gas, uses ultra-low temperatures and purification. In this study, the assessment of LNG carrier vehicles was evaluated from the perspective of Bangladesh. A cryogenic liquid tanker truck, called an LNG carrier vehicle, was found in the survey to carry liquefied natural gas in an environment with extremely low temperatures. Even though LNG is flammable, explosive, cryogenic, and has other characteristics, the safety design of an LNG carrier vehicle is crucial for the security of road transportation. Time consumption analysis and economic section analysis were conducted, and the truck was found to be the ultimate solution. LNG cryogenic liquid storage tanks, trailer running gear, piping systems, a control box, and other parts are often found in LNG carrier vehicles. Utilizing statistical tools, the validity of the survey and its findings will be evaluated by the Statistical Package for the Social Sciences (SPSS). The safety design study for these two systems was the topic of this work. A report on the compatibility of the best method for transporting LNG within all feasible safety conditions will be made possible by the research.

Analysis of the Experimental Data of Slamming Loads on a Liquefied Natural Gas Carrier in Abnormal Waves

Abstract The objective of the paper is to identify slamming characteristics of ships in abnormal waves by analyzing the experimental slamming loads for a liquefied natural gas (LNG) carrier from the model tests of the ship, which were conducted at the Ocean Engineering Division of the Technical University Berlin at a model scale of 1:70. To validate the experiments, the numerical results from a time domain nonlinear strip theory code are compared with the measurement of the ship motions and vertical bending moment amidships of the LNG carrier in the New Year wave. The time series of the slamming pressures on different locations (on the bow and stern) obtained in the experiments are analyzed and discussed by studying the peaks using the analytical distribution models, namely, Weibull distribution, generalized extreme value distribution, and the Gumbel distribution. The extreme values of the pressure peaks obtained using the three distribution models are compared. Discussion is also provided for the results with two different Froude numbers in order to check the effects of the ship speed on the phenomenon.

Risk informed floating storage and re-gasification unit (FSRU) location selection for local natural gas supply

In the present energy market due to high demand of liquefied natural gas (LNG) and the limited availability of land-based LNG import terminals, the use of offshore LNG terminals is destined to increase. Such terminals are referred to as LNG floating storage and re-gasification units (FSRUs). An FSRU terminal is a cost-effective and a time-efficient solution to quickly open up supply to onshore users with minimal environmental impact. This work focuses on the selection from a safety point of view of a possible location for an offshore or nearshore FSRU, given alternative candidate locations. For decision making, the maritime and process safety aspects of the LNG resupply operation have to be considered. This involves the approach of an LNG Carrier (LNGC) to resupply the FSRU. The whole resupply process is divided into three consecutive parts, beginning with the LNGC navigating in the inbound channel, going through its berthing operation, and ending with transfer of the LNG. The safety of the third part, the LNG transfer to the FSRU, could be evaluated by means of a quantitative risk assessment. For the maritime operations this was not possible and evaluation had to rely on expert elicitation. To create a comparison basis of navigating, turning and berthing hazards with the risks of the LNG transfer process, a novel safety utility value (SUV) was defined existing of five ranges. Hazard attributes of navigating and of turning and berthing of the maritime operations were identified/confirmed by simulator runs, their importance was ranked, as well as their safe operating ranges determined with the aid of queries to a large group of experts. Importance ranking was based on pairwise comparison judgment, responses aggregated by means of fuzzy number fits, processed in square matrices. Expert elicitation yielded safety attribute values (SAVs) for the five SUV ranges which were statistically treated. QRA provided potential loss of life (PLL) values, which also were converted into SUV ranges. Based on the importance ranking of the three parts and the SUVs, final results were obtained.

Experimental investigation on ice resistance of an arctic LNG carrier under multiple ice breaking conditions

In order to investigate the ice loads of an Arctic LNG carrier under different ice conditions, a series of model tests are carried out in an ice tank, the ship model is attached to the towing dynamometer and the resistance force is measured for the specified model speed in level ice, broken ice and brash ice. During the test observations, several phenomena, including the ice-hull interaction modes and the failure modes of ice are captured. Ice loads in level ice and brash ice condition present a characteristic of periodicity, while ice force fluctuated randomly in broken ice because of nonuniform distribution of ice foes. The results also show that ice resistance has a liner fitting relationship with the ship speed. The achievable speed in broken ice condition is almost 3.5 times of that in level ice with the same thickness. With the same thrust power and the same speed, in brash ice condition, the ship can transit the ice 2.7 times thickness of that in level ice condition. Besides, model test results are compared with the results derived from some empirical formulas and the empirical formulas appropriate for resistance estimation in different ice conditions are summarized according to the comparison result. Lindqvist formula is suitable for ice resistance in level ice condition, Zuve & Dobrodeev formula coincides well with the experimental result in broken ice condition, Dobrodeev formula is proper for ice resistance in brash ice condition.

Sloshing Phenomenon Occurring in the Foremost Two Tanks of LNG Carrier

Sloshing Phenomenon Occurring in the Foremost Two Tanks of LNG Carrier

GREENHOUSE GAS EMISSION AND THEIR TREND PREDICTION USING AIS AND TRADE DATA

Due to decarbonization and greenhouse gas (GHG) emission reduction attempts nowadays, liquefied natural gas (LNG) has become widely used as an alternative marine fuel. As Japan is the top global LNG importer and one of the largest crude oil importers, this study focuses on LNG and tanker shipping and their emissions in Japan, and import volumes. In this study, the emission estimation model is constructed based on the Holtrop-Mennen power prediction method. Using automatic identification system (AIS) data, fuel consumption and GHG emissions are estimated. Next, long term GHG emission is predicted using hthe Japan trade statistics. Combining the vessel movement data and trade statistics, GHG emission in Japan is projected to decline over years for tankers, and to remain stable for LNG carriers. The results could be considered in formulating environmental and trade policy. It is hoped the study will provide useful insights for zero emission projects and implementations in Japan.

Impact failure characteristics of LNG carrier cargo containment system

The most critical issue related to the maritime transportation of liquefied natural gas (LNG) is the structural safety of the cargo containment system (CCS), because LNG is stored at temperatures below –163 °C. During the unloading of LNG, several types of structural components can fall into CCSs from significant heights. Thus, the structural safety of LNG CCSs against dropped objects should be verified; however, the actual failure characteristics of the primary barrier are not well understood. In this study, the failure mechanism of the primary barrier of an LNG CCS was investigated by conducting falling-object-induced structural failure tests. To clarify the effect of the failure response of the primary barrier, impact tests were performed using various membrane types and impactor types. In addition, to ensure the wide applicability of the results, a finite element analysis-based design-aid numerical method was developed by comparison with experimental observations. Excellent numerical verification results were obtained using the Johnson–Cook material model, which can be applied to the dynamic failure problem for the corrugated plates used in LNG CCSs. Finally, guidelines that could set safety standards for the primary barrier were identified, considering the shape, weight, and height of potential falling objects.

Analysis of the peaks of ship motions in linear and nonlinear focused waves

Three focused waves, which have almost identical temporal profiles, are successfully generated in a numerical wave tank with both linear and nonlinear methods, and they are utilized to act upon an LNG carrier to study the induced differences of the ship peak responses for the first time. The influences of focal location and incident wave direction are taken into account and the fundamental reason for the response difference is revealed from the perspective of energy variation. It can be concluded that when the LNG carrier encounters the same temporal focused waves, the peak motion responses can be different due to the different hydrodynamic characteristics under the focused crests, which can be further attributed to the distinct physical mechanisms involved in the energy concentration of these focused waves. The focal location and incident wave angle can further enlarge the corresponding discrepancy under some circumstances. From a spectral point of view, the motion discrepancy is mainly caused by the actions of the distinct fundamental wave components. Specifically speaking, the relatively high-frequency components of the nonlinear focused waves tend to induce a smaller heave response and the quasi-monochromatic wave component cannot trigger a larger pitch motion than the linear focused waves.

A novel pre-processing modelling method for the finite element analysis of the thermal deformation of large structures in the erection stage

The manufacturing process of ships and offshore structures comprises several stages, which include plate cutting, sub-assembly, block assembly, pre-erection, and erection. Accuracy and quality control management are crucial issues in the manufacturing process. Welding-induced distortion and deformation complicate the assembly stage in shipyards. Through conventional finite element (FE) analysis, the manufacturing process can be predicted and controlled up to the sub-assembly stage; however, applying the FE method to the stages between block assembly and erection is difficult. In this study, a new FE analysis method for predicting welding-induced thermal deformation of large blocks, which was difficult to predict with traditional methods, was proposed. In addition, based on this result, we developed a novel pre-processing modelling system that can automatically extract the erection weld lines and automatically divide blocks, which are necessary for the thermal deformation analysis of large blocks. Validation experiments confirmed the applicability of the proposed method to the shaft alignment of a container ship and LNG carrier, with industrial accuracy and quality control in the manufacturing process. Compared with existing methods, the proposed method increases the accuracy of the analysis and reduces the total pre-processing time.

Maritime inventory routing with transshipment: the case of Yamal LNG

The LNG-ADP problem is a tactical planning problem for creating an annual delivery program (ADP) for a liquefied natural gas (LNG) producer. An ADP specifies the departure dates of the LNG carriers as well as the delivery dates at the different customers for a period of 12–18 months. The problem can be formulated as maritime inventory routing problem, as it is an important requirement to plan the deliveries such that inventory levels are kept within minimum and maximum limits at the customers as well as the LNG production facility. Inspired by the case of Yamal LNG, we propose a novel discrete-time formulation for the LNG-ADP problem with transshipment and intermediate storage. Our formulation also allows for waiting at the unloading ports. The problem is solved using a rolling horizon heuristic (RHH) for a case based on the Yamal LNG project. We study the impact of different RHH configurations on run time and solution quality. The results show that using a central period that is shorter than the forecast period provides the best objective function, whereas a central period that is longer than the forecast period improves run time. We also explore the effect of allowing waiting at the unloading ports. Waiting does not necessarily improve the objective function value, despite increasing the solution space. However, we observe a reduction in run time for instances where waiting is allowed.

Comparative safety assessment of LNG re-liquefaction systems applied on LNG carriers

ABSTRACT This research was aimed to evaluate the safety of the LNG cargo compressor room against unwanted gas leakage from two different re-liquefaction systems applicable for an LNG carrier: 1) the Partial (Full) Re-liquefaction System (P(F)RS) and 2) the combination of Partial Re-liquefaction System and Mixed Refrigerant Re-liquefaction system (PRS+MRS). To achieve this goal, quantitative risk assessment was carried out with the integration of system hierarchical modelling, statistical analysis, and CFD simulation. The frequency of initial leakages, occurring to each component of the re-liquefaction systems, was analysed, whereas for the consequence analysis, a CFD program of PyroSim was employed to simulate the gas dispersion in the confined room fitted with mechanical ventilation systems. In addition, various ventilation capacities were investigated with changes in their allocations in the room in order to determine these parametric influences on the results. The risk level of re-liquefaction systems was determined in a quantitative way. Research results clearly presented the importance of the proper arrangement of the ventilation systems. The risk levels were estimated at 5.6 E-3/year for P(F)RS whereas about 9.6 E-3/year for the PRS+MRS in consideration of current regulations. However, the increase in the ventilation capacity was found to reduce the risk levels. The research findings are highly believed to offer meaningful guidance into future safety regulatory frameworks.