Gases In Bulk Research Articles

A novel approach to developing effective maritime regulations: The case of LNG cargo filling limits

ABSTRACT This paper introduces a novel approach to resolving a part of the fundamental problems encountered in the current practice of maritime regulatory frameworks. The novelty of the proposed method lies in a detailed and structured process that can examine and verify the appropriateness of a particular regulation in terms of integrating economic, environmental and safety impacts. Through its built-up database of approximately 440 LNG carriers in the world, the excellence of the proposed approach has been demonstrated by investigating the suitability of a controversial regulation related to the LNG cargo filling limit set forth in “the International code for the construction & Equipment of Ships carrying liquefied gases in Bulk.” A series of case studies have confirmed 169 LNG carriers currently are subjected to being placed under this issue. In this study, we identified ships’ key characteristics which would contribute to the increase in total costs associated with economic, environmental and safety impacts and presented the threshold between the opportunity costs and the severity of the regulation. The research findings have provided a managerial insight that may increase the reliability of maritime regulations by applying this pragmatic/analytical regulatory framework model developed in this research.

Optimal Gas Detection System in Cargo Compressor Room of Gas Fueled LNG Carrier

This study analyzes the optimal location of gas detectors through the gas dispersion in a cargo compressor room of a 174K LNG carrier equipped with high-pressure cargo handling equipment; in addition, we propose a reasonable method for determining the safety regulations specified in the new International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC). To conduct an LNG gas dispersion simulation in the cargo compressor room-equipped with an ME-GI engine-of a 174 K LNG carrier, the geometry of the room as well as the equipment and piping, are designed using the same 3D size at a 1-to-1 scale. Scenarios for a gas leak were examined under high pressure of 305 bar and low pressure of 1 bar. The pinhole sizes for high pressure are 4.5, 5.0, and 5.6mm, and for low pressure are 100 and 140 mm. The results demonstrate that the cargo compressor room will not pose a serious risk with respect to the flammable gas concentration as verified by a ventilation assessment for a 5.6 mm pinhole for a high-pressure leak under gas rupture conditions, and a low-pressure leak of 100 and 140 mm with different pinhole sizes. However, it was confirmed that the actual location of the gas detection sensors in a cargo compressor room, according to the new IGC code, should be moved to other points, and an analysis of the virtual monitor points through a computational fluid dynamics (CFD) simulation.

Regulatory gaps between LNG carriers and LNG fuelled ships

Given a number of marine vessels treating the liquefied natural gas either as cargo or fuel, this paper examined the regulatory gaps of two different international Codes – the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk and the International Code of Safety for Ships Using Gases or Other Low-flashpoint Fuels – from the regulatory standpoint. Results of the gap analysis have identified and discussed the key areas encountered with regulatory discrepancies or ambiguities that might interrupt the proper design, construction and operation of LNG carrier and LNG fuelled ship. A systematic investigation and harmonisation process across the Codes was proposed to mitigate the potential issues that may arise from the discordant regulations. Also, the International Maritime Organization was suggested to take proactive action to improve such dissonances while a general insight into the importance of filling those gaps was provided for rule-makers and stakeholders.

Calculation of Boil-Off Gas (BOG) Generation of KC-1 Membrane LNG Tank with High Density Rigid Polyurethane Foam by Numerical Analysis

Abstract Recently, a new type of LNG tank named “KC-1 membrane LNG tank” has been developed by Korean Gas Corporation (KOGAS), and Samsung Heavy Industries (SHI) is currently building KC-1 membrane type LNG carriers. Unlike other LNG tanks, the KC-1 membrane LNG tank has a single-insulation structure rather than a double-insulation structure. For a given tank’s boundary condition, heat transfer analysis is performed from the external to the internal environment of the LNG tank by numerical simulation for three tanks. In each tank, the main thermally resistant layer of insulation is assembled with a High density rigid Polyurethane Foam (H-PUF), which is blown with one of three different types of hydrofluorocarbons-namely-HFC-365mfc, 245fa, and 245fa-e (enhanced). Advantage of such blowing agents is that it has a lower Ozone Depletion Potential (ODP) than HCFC-141b or carbon dioxide (CO2) that has been used in the past as well as having low thermal conductivity. A Reduced Order Model is utilized to a 3-dimensional section of the insulation to calculate equivalent thermal conductivity. The equivalent thermal conductivity of the insulation is then applied to the rest of LNG tank, reducing the size of tank simulation domain as well as computation time. Tank’s two external and internal boundary conditions used are those defined by the International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC) and the United States Coast Guard (USCG) conditions. Boil-off Rate (BOR) of the tank that has the insulation with H-PUF blown with HFC-245fa resulted in 0.0927 %/day and 0.0745 %/day for IGC and USCG conditions, respectively.

Estimation of the design pressure of a prismatic LNG storage vessel

This study proposed a method of estimating to design pressure in a prismatic storage vessel for liquefied natural gas. The estimation of the design pressure refers to the IGC Code that provides the international standards for storage of liquefied gases in bulk. The estimation of the design pressure was a basic step to scheme a storage vessel. The design pressure resulted from the vapor pressure and the maximum liquid pressure. The liquid pressure was calculated from the effect of gravity and the acceleration applied to the center of gravity of the liquid. Loading conditions of up to 98% were considered in the calculation of the maximum liquid height. The heat ingress warmed the LNG, which caused it to exceed its boiling temperature. Calculation of the vapor pressure was described by the material and energy balance equations. Dynamic simulation about the pressure behavior was conducted by commercial software. The vapor pressure affected by heat ingress from surrounding conditions was calculated with time variations.

The Internal Pressure Calculation of Type C Independent Tanks ofMiniature LNG Carrier

According to IMO “International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk” and the relevant regulations for pressure containers,“GB150.3-2011”,a 3-dimensional method for the calculation of internal pressure of Type C independent tanks of miniature LNG carrier is given in this paper. With the assistance of the modeling and calculating function of AutoCAD,the VBA secondary development is used to achieve the 3-dimensional calculational of the internal pressure and thickness of plates. Also,the internal pressure of a Type C independent tank is calculated with both the 3-dimensional method and traditional 2-dimensional method separately,and the obtained results are compared carefully. Meanwhile,the influence of the acceleration caused by ship motion on the results is analyzed. It is shown that the 3-dimensional method yields more accurate results and it is preferable in the precision design. However,in real projects,the traditional 2-dimensional method is also applicable in the internal pressure calculation of single-cylinder Type C independent tanks of a design steam pressure over 0.3 MPa in general,and the influence of the acceleration caused by ship motion cannot be ignored. The 3-dimensional method should be taken for the internal pressure calculation in the tanks of other types in lower design steam pressure.

An experimental study on fatigue performance of cryogenic metallic materials for IMO type B tank

Three materials SUS304, 9% Ni steel and Al 5083-O alloy, which are considered possible candidate for International Maritime Organization (IMO) type B Cargo Containment System, were studied. Monotonic tensile, fatigue, fatigue crack growth rate and Crack Tip Opening Displacement tests were carried out at room, intermediate low (-100 oC) and cryogenic (-163 oC) temperatures. The initial yield and tensile strengths of all materials tended to increase with decreasing temperature, whereas the change in elastic modulus was not as remarkable. The largest and smallest improvement ratio of the initial yield strengths due to a temperature reduction were observed in the SUS304 and Al 5083-O alloy, respectively. The fatigue strengths of the three materials increased with decreasing temperature. The largest increase in fatigue strength was observed in the Al 5083-O alloy, whereas the 9% Ni steel sample showed the smallest increase. In the fatigue crack growth rate test, SUS304 and Al 5083-O alloy showed a decrease in the crack propagation rate, due to decrease in temperature, but no visible improvement in da/dN was observed in the case of 9% Ni steel. In the Crack Tip Opening Displacement (CTOD) test, CTOD values were converted to critical crack length for the comparison with different thickness specimens. The critical crack length tended to decrease in the case of SUS304 and increase for the Al 5083-O alloy with decreasing temperature. In case of 9% Ni steel, change of critical crack length was not observed due to temperature decrease. In addition, the changing material properties according to the temperature of the LNG tank were analyzed according to the international code for the construction and equipment of ships carrying liquefied gases in bulk (IGC code) and the rules of classifications.

Cargo Conditions of CO2 in Shuttle Transport by Ship

For shuttle transport of liquid CO2 in ship-based CCS, the cargo conditions were investigated in view of the pressure tank manufacturability, the cost of the tanks and the carrier vessel, the total energy efficiency of the CO2 flow, etc.In a CCS chain, since the critical path might be the injectivity of the well, the unit cargo of a carrier vessel is set to 3000 tonnes, which is equivalent to the Sleipner case, annual injection rate of ca. 1 million tonnes.The physical properties of CO2, specifically the vapor liquid equilibrium properties of CO2, are such that the design of a storage tank for the containment of liquid carbon dioxide is very similar to existing designs for intermediate pressure liquefied petroleum gas (LPG) containment systems. The design methodology for LPG cargo tanks is well understood and is regulated by international standards (specifically the “International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk”; IGC code) and Classification Societion Societies (such as DNV, BV and LRS) The disign methodology employed in this study, which is for the marine transport of LCO2 is exactly the same as described by the IGC code and subject to Classification Society rules. These design rules are well proven with literally hundreds of LPG carriers operating worldwide in an industry that has an excellent safety record since the advent of LPG bulk marine transport in the early 1960s. The proposed ship design which installs two cargo tanks was as follows:-the volume of the tanks is about 1500m3 and design pressure and temperature are 3.10MPa and munus 10degC, respectively.-The shape of the tanks is a cylindrical bilobe with single cylinder radius of 3.50 m and 26.96m in lengthThe necessary facilities for LCO2 loading from land-based storage tanks are also examined, including CO2 buffer storage tanks, the loading pumps, the loading arms, and so on. The offshore delivery and injection system are investigated and the resultant design proposal was as follows: the temperature of the cargo LCO2 is raised to 5degC by on-board heat exchange system using the ambient seawater.The cost estimate of the proposed system will be also given in the presentation.The study is a part of the Preliminary Feasibility Study on CO2 Carrier for Ship-based CCS and its follow-up study sponsored by Global CCS Institute and conducted by Chiyoda Corporation. The other technical parts of the study are Ship-based offshore CCS featuring CO2 shuttle ships equipped with injection facilities by M Ozaki et al, “Offshore operational availability of onboard direct injection of CO2 into sub-seabed geological formations” by T Miyazaki et al, and “Onboard CO2 injection into subseabed geological formation via picked-up flexible pipe by N. Nakazawa et al.

A Static Dilution System to Produce Trace Level Gas Standards for Chromatography

Equipment for producing gas standards for quantitative trace chromatographic analysis of extraneous gases in hydrogen is described. Several mixtures of small amounts of dry atmospheric air and ultrapure hydrogen and of concentrated gas mixtures in ultrapure hydrogen are made in a static-type system. In the air samples, the N 2 concentration varies between 0-410 μL/L, and the O 2 concentration varies between 0-115 μL/L. Calibration of the system and method, as well as data showing reproducibility, are reported. The results indicate that the system produces gas standards for quantitative analysis of O 2 , N 2 , and other gases in bulk H 2 . The advantages of this method are its versatility and reliability.

Observation of steady state transient ‘wiggles’ phenomenon in bulk gases

The observation of the electric dipole analogue of the ‘wiggles’ phenomenon of n.m.r. is reported for NH 3 and OCS gases in bulk. The method described permits relaxation times to be measured as a function of gas pressure.