Initial Design and Analysis of a Compressed Natural Gas Transport System

2021 ◽  
Author(s):  
Decao Yin ◽  
Halgeir Ludvigsen ◽  
Halvor Lie ◽  
Ivar Fylling
Keyword(s):  
Natural Gas ◽  
Positioning System ◽  
Preliminary Design ◽  
Sea State ◽  
Compressed Natural Gas ◽  
Environmental Loads ◽  
Dynamic Positioning System ◽  
Flexible Pipes ◽  
Natural Gas Transport ◽  
Positioning Analysis

Abstract Offloading hoses/flexible pipes are used to transfer compressed natural gas (CNG) from an intermediate floating storage and offloading unit (FSO) to CNG vessel (GASVESSEL). The floating hoses are subjected to environmental loads that are mainly waves, current, and vessel motions from both the FSO and the CNG vessel. Preliminary design of loading/unloading system and dynamic positioning system has been performed. Dynamic analysis of the loading/offloading hose and positioning analysis of the FSO and CNG vessel have been carried out numerically in this study. It is verified that the designed loading/unloading system and positioning system of the two vessels (FSO and CNG vessel) are able to operate safely under the sea-state Hs = 6 m within the defined ESD1 zone.

scholarly journals A Novel Three-SPR Parallel Platform for Vessel Wave Compensation

2020 ◽  
Vol 8 (12) ◽  
pp. 1013
Author(s):  
Yong Zhan ◽  
Huichun Tian ◽  
Jianan Xu ◽  
Shaofei Wu ◽  
Junsheng Fu
Keyword(s):  
Compensation Effect ◽  
Kinematic Model ◽  
Inverse Kinematic ◽  
Ship Motion ◽  
Forward Kinematics ◽  
Positioning System ◽  
Sea State ◽  
Dynamic Positioning System ◽  
Upper Deck ◽  
Parallel Platform

A wave compensation platform based on 3-SPR parallel platform is designed for marine ships with a dynamic positioning system. It can compensate for the heave, rolling, and pitching movement of a vessel under level 4 sea state. The forward kinematics of the mechanism is used to draw the central point position workspace and the attitude workspace of the moving deck of the compensation platform. The compensation effects of the 3-RPS parallel compensation platform and the 3-SPR parallel compensation platform are compared, and the feasibility and superiority of the compensation scheme using the 3-SPR parallel compensation platform are proved. To lower the working height of the upper deck of the compensation platform and reduce the extension range of the support legs, the structure of the compensation platform is optimized, and a novel 3-SPR parallel platform is designed. Finally, a simulation model was established. Using the inverse kinematic model as a compensation movement solver which can online calculate the length of branch legs based on the measured heaving, rolling, and pitching values of vessels, the compensation effect of the new structure under a certain sea state is simulated. The result demonstrated the efficiency of the ship motion decoupling movement of the newly designed compensation platform and proved the competence of it.

Time Domain Simulation of a Dynamic Positioning Deepwater Semisubmersible Drilling Platform

2014 ◽  
Author(s):  
Xu Yang ◽  
Liping Sun ◽  
Shuhong Chai
Keyword(s):  
Time Domain ◽  
Numerical Study ◽  
Angular Speed ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Time Domain Simulation ◽  
Proportional Integral Derivative ◽  
Floating Structures ◽  
Environmental Loads ◽  
Dynamic Positioning System

DPS (dynamic positioning system) has been widely used in floating structures, especially in deepwater area. Time domain simulation of platforms with dynamic positioning system has great significance to DP capability and riser system. Motion response of a deepwater semi-submersible platform with DPS on time domain was presented in this paper. PID (proportional, integral, derivative) controller and thruster allocation method were applied in numerical simulations of DPS. Wind, current and wave environmental loads were analyzed and limited angular speed was considered as well. Thruster failure analyses were covered and discussed also. Experiments of DPS in deep-water basin of Harbin Engineering University (HEU) were presented and compared with numerical study.

scholarly journals Application of ASME Section VIII Division 3 to Compressed Natural Gas Transport

2013 ◽  
Author(s):  
J. Robert Sims
Keyword(s):  
High Pressure ◽  
Natural Gas ◽  
Gas Transport ◽  
Composite Fiber ◽  
Pressure Vessels ◽  
Liquefied Natural Gas ◽  
Compressed Natural Gas ◽  
Marine Transport ◽  
Section Viii ◽  
Natural Gas Transport

Marine transport of liquefied natural gas (LNG) is well established and extensive precedents for the design of the ships and tanks exist. Fewer precedents exist for the transport of compressed natural gas (CNG). This paper describes the application of composite (fiber) wrapped pressure vessels constructed to the requirements of ASME Section VIII Division 3, Alternative Rules for Construction of High Pressure Vessels (Division 3) to pressure vessels for marine CNG transport. Since the density of CNG is much lower than the density of LNG, efficient transport requires that the pressure vessels be as light as possible while ensuring pressure integrity. The advantages of a composite fiber wrap and of Division 3 construction for this application will be discussed. Paper published with permission.

Utilization of FMEA During the Preliminary Design of a Dynamic Positioning System for a Shuttle Tanker

2008 ◽  
Author(s):  
La´zaro Moratelli ◽  
Eduardo A. Tannuri ◽  
He´lio M. Morishita
Keyword(s):  
Reliability Analysis ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Preliminary Design ◽  
Effect Analysis ◽  
Dynamic Positioning System ◽  
Failure Data ◽  
Dynamical Simulations ◽  
Offshore Oil Industry ◽  
Offshore Oil

The Dynamic Positioning mode operation of vessels, especially those related to the offshore oil industry, requires rigorous reliability analysis in order to eliminate the dangerous consequence of loosing position or to create a procedure when the consequence can not be eliminated. In general, the reliability analysis of the Dynamic Positioning System (DPS) is performed through Failure Mode and Effect Analysis (FMEA). In this paper the FMEA procedure is proposed taking into account the failure data reported in IMCA DP Incidents Reports. The idea of this procedure is to analyze and improve the system configuration during preliminary design in terms of the reliability considering critical failures. To complete the analysis, the consequence is evaluated through dynamical simulations for offloading operation in tandem configuration. The simulations results indicate the need to improve the DPS configuration and three modifications are proposed to compensate and create redundancy to avoid occasional failures of the propellers are proposed.

Realistic Adaptive DP Controller for Flotel Operating in Side-by-Side Configuration With FPSO

2019 ◽  
Author(s):  
A. Yenduri ◽  
A. R. Magee ◽  
J. Liu ◽  
W. Xu ◽  
A. Choudhary ◽  
...  
Keyword(s):  
Neural Network ◽  
Shielding Effect ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Sea State ◽  
Large Wave ◽  
Dynamic Positioning System ◽  
The Neural Network ◽  
Ocean Environment ◽  
State Detector

Abstract Side-by-side operation of multiple floaters in the ocean environment is very challenging and the operators always prefer a maximum operable weather window, in order to minimise the cost incurred from the downtime. The safety of the gangway connecting the floaters is very crucial and its dynamic response in the ocean environment raises concerns during operations. Therefore, an efficient dynamic positioning system is essential to maintain the floater and ultimately, the gangway response within the desired limits. In this work, a novel dynamic positioning system for floater operating aside another vessel is presented. The system includes an adaptive controller combined an optimised thruster allocation law and with a sea state detector. The adaptive control is achieved by using the barrier Lyapunov function and a predictor-based method in combination with the neural network scheme. The limitations include the saturation of inputs and the forbidden zones due to thruster-thruster or thruster-hull interaction. An optimised allocation for lower fuel consumption, wear and tear of the thruster equipment and to ensure the resultant command in the respective direction of the azimuth thrusters is designed. The optimisation here is a non-convex problem and a locally convex reformulation of second order is implemented. The presence of unknown shielding effect due to nearby vessel in a side-by-side configuration and input time delay is also considered in the development of this thruster allocation law. In order to overcome these effects, a novel sea state detector is designed. The sea state detector can effectively monitor the variation of drift wave-induced force on the vessel and activate the neural network compensator in the controller when a large wave drift force is identified. Simulation studies are conducted to verify the efficiency of this dynamic position system and a demonstration of flotel in side-by-side configuration with a turret moored FPSO is presented for the non-collinear ocean environment.

scholarly journals A Study on the Effectiveness of the Heading Control on the Mooring Line Tension and Position Offset for an Arctic Floating Structure under Complex Environmental Loads

2021 ◽  
Vol 9 (2) ◽  
pp. 102
Author(s):  
Hyun Hwa Kang ◽  
Dae-Soo Lee ◽  
Ji-Su Lim ◽  
Seung Jae Lee ◽  
Jinho Jang ◽  
...  
Keyword(s):  
Standard Procedure ◽  
The Arctic ◽  
Mooring Line ◽  
Dynamic Positioning ◽  
Positioning System ◽  
Station Keeping ◽  
Mooring Lines ◽  
Environmental Loads ◽  
Dynamic Positioning System ◽  
Heading Control

Even though interest in developing the Arctic region is increasing continuously, the standard procedure to be used to analyze the station-keeping performance of a floater considering ice loads has not been established yet. In this paper, the effectiveness of heading control with a dynamic positioning system is analyzed to evaluate the improvement of the performance of the station-keeping system in the ice conditions. Complex environmental loads with ice-induced forces were generated and applied to a ship type floater with dynamic positioning and mooring systems. Three-hour time-domain simulations were conducted for the two different station-keeping systems with mooring only and mooring with a dynamic positioning system. Position offsets and mooring line tensions for the two scenarios were compared with maximum values and most probable maxima (MPM) values. The results of the simulation showed that the heading control can reduce 8.2% of MPM values for the mooring lines and improve the station-keeping performance by about 16.3%. The validity of the station-keeping system that was designed was confirmed, and it is expected that the specification of mooring lines can be relaxed with the heading control.

Effects of Wave Drift Forces on Maneuvering of Ship

2008 ◽  
Author(s):  
Takeshi Kinoshita ◽  
Weiguang Bao ◽  
Motoki Yoshida ◽  
Yasunori Nihei ◽  
Yongze Xu ◽  
...  
Keyword(s):  
Dynamic Positioning ◽  
Positioning System ◽  
Ocean Engineering ◽  
Sea State ◽  
Dynamic Positioning System ◽  
Wave Drift ◽  
Wave Basin ◽  
Wave Drift Damping ◽  
Wave Drift Forces ◽  
Drift Forces

The dynamic positioning system of floating ocean structures requires hydrodynamic force derivatives to construct an accurate maneuvering model. In a severe sea state, the effects of ambient wave field on the maneuvering properties are not negligible. To investigate wave drift forces affecting on maneuvering of a ship relating to dynamic positioning system, an innovative model test, i.e. the Planer Motion Mechanism (PMM) test in waves is discussed in the present paper. Meanwhile, a theory to evaluate wave drift force including wave drift damping and wave drift added mass is summarized. Some examples of experiments done in Ocean Engineering Wave Basin of Institute of Industrial Science, University of Tokyo are presented and compared with calculated results based on the above theory.

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