Ballast Water System Research Articles

Dynamic and structural analyses of floating dock operations considering dock-vessel coupling loads

Floating docks are important for increasing the capacity of land-based shipyards and serve as essential platforms for vessel construction, maintenance, and repair. As the size of modern vessels increases, ensuring the structural safety of the floating docks becomes challenging. To enhance the operational safety of the floating docks, this study aims to develop an in-house code for a comprehensive global response assessment of a full-scale floating dock. The code is developed under a quasi-static assumption and enables dynamic and structural response assessments for the floating dock and docked vessel during the vessel-docking operations. The floating dock and docked vessel are represented as rigid bodies with six degrees of freedom and subjected to hydrostatic, hydrodynamic, mooring, and contact loads. The piping network of the floating dock's ballast water system is modelled to calculate the flow rates out of all ballast tanks. A modified proportional controller (P-controller) is employed to achieve automatic ballast control, regulating opening angles of ballast tank valves to minimize roll and pitch motions of the floating dock and docked vessel. For structural response assessment, a bending model is proposed to evaluate the bending deformation of the floating dock based on the load distribution along the dock's length. Results show that the present code can successfully simulate the vessel-docking process. The automatic ballast control strategy effectively minimizes roll and pitch for both the floating dock and docked vessel, ensuring stable control of the entire system. Minimal discrepancies are observed in the dynamic responses and bending of the floating dock between one- and two-way couplings. The longitudinal shift of the docked vessel's centre of gravity (CoG) increases the relative motions between the docked vessel and the floating dock, especially in surge, sway and pitch. A significant shift distance might cause the mooring rope breakage. Positioning the vessel's CoG closer to the dock's CoG proves safer for vessel-docking operations. In general, the developed code can support the decision-making for dock masters and optimize the docking plan.

Ship Ballast Water System Fault Diagnosis Method Based on Multi-Feature Fusion Graph Convolution

To tackle the issues of limited fault data, inadequate information availability, and subpar fault diagnosis within the realm of ship ballast water system condition monitoring, this paper presents a novel fault diagnosis methodology known as the Probabilistic Similarity and Linear Similarity-based Graph Convolutional Neural Network (PCGCN) model. PCGCN initially converts the ship’s ballast water system dataset into two distinct graph structures: a probabilistic topology graph and a correlation topology graph. It delves into data similarity by employing T-SNE for probabilistic similarity and Pearson’s correlation coefficient for linear similarity to establish the inter-sample neighbor relationships. Subsequently, an early fusion of these two graph structures is conducted to extract more profound multi-scale feature information. Following this step, the graph convolutional neural network (GCN) is introduced to amalgamate the feature information from neighboring nodes in addition to its inherent features. This is aimed at enhancing the available information for the classification task and addressing the issues of limited fault data and inadequate label information. In conclusion, we employ a simulated ship fault dataset for testing experiments, and the PCGCN model demonstrates superior classification accuracy, reaching 97.49%, outperforming traditional diagnostic methods. These experimental outcomes underscore the applicability of the model introduced in this study to the realm of ship ballast water system fault diagnosis, even under challenging conditions characterized by limited sample sizes and insufficient labeling information.

Fault Diagnosis of Ship Ballast Water System Based on Support Vector Machine Optimized by Improved Sparrow Search Algorithm

Fault Diagnosis of Ship Ballast Water System Based on Support Vector Machine Optimized by Improved Sparrow Search Algorithm

Numerical Study on the Automatic Ballast Control of a Floating Dock

Abstract The ballast control of a floating dock mainly relies on manual operations, which can be time-consuming and requires skilled workers. This study proposes an automatic ballast control system for floating docks, which improves operational efficiency and safety during the vessel docking process. A numerical model is developed to simulate the dynamic process of the floating dock's operations, which includes a six degrees-of-freedom (6DOF) model, a hydrostatic force model, a hydrodynamic force model, and a hydraulic model. The hydrostatic force model is developed using the Archimedes law and a strip theory along the longitudinal direction. The hydrodynamic model is made based on the effects of added mass and dynamic damping. The hydraulic model is proposed to deal with the hydraulic calculation of the ballast water system. The present automatic ballast control is designed based on a modified proportional controller (P-controller) to control the valve opening angles when the pitch or roll angles are larger than the corresponding threshold values. Without using controllers, the roll angles of the dock can reach 8.9 deg and 13 deg during the ballasting and de-ballasting operations, respectively. The present modified P-controller with optimized control parameters can stabilize the dock during the de-ballasting operation and keep the maximum pitch and roll angles no larger than 0.016 deg and 0.0783 deg, respectively. During the ballasting operation with the same control parameters, the roll and pitch are below 0.0604 deg and 0.0145 deg, respectively. The present automatic control will be further implemented in the vessel docking cases and can significantly improve the stability of the dock.

Numerical study on the de-ballasting operation of a floating dock with a malfunctioning pump

In normal de-ballasting operations of floating docks, each ballast pump manages a specific group of ballast tanks, independently of the others. However, if one pump is malfunctioning, a connection valve between the group and its adjacent group is opened, allowing its adjacent pump to control two groups of tanks simultaneously. This study aims to investigate the de-ballasting dynamic process in the event of a ballast pump malfunction by utilizing a numerical model of a full-scale digital floating dock. In the present numerical model, the dock is represented as a rigid body with six degrees of freedom and is subjected to hydrostatic, hydrodynamic, and mooring forces. To maintain pitch and roll angles within predefined limits, a modified P-controller is employed to regulate the valve opening angles at all the ballast tanks. Hydraulic calculations for the ballast water system with a malfunctioning pump are conducted, and the numerical results demonstrate the effectiveness of the present modified P-controller when dealing with a malfunctioning Pump No. 1.

Numerical simulation of damping effect of ballast water system on motion response of immersed tunnel element

The OpenFOAM was extended to analyze the roll motion of an immersed tunnel element excited by outside waves and inside ballast water sloshing. The reliability of our numerical model was validated by comparing the results with related experimental tests. Then, the effect of filling depths of ballast water on damping roll motion of a 2-D tunnel cross-section excited by regular waves was analyzed, and the effect of tank width with constant filling weight on rigid-fluid coupling was also discussed. Results revealed that a crucial filling depth for best damping performance on roll motion of liquid-carrying structures exists between the dry condition and the filling depth corresponding to the most severe resonance condition. For the application of the tunnel element in this study, a dimensionless filling depth of 0.1 shows the best damping effect. Furthermore, for different tank widths with a constant filling weight, the damping effect of the ballast water is mainly dominated by the natural frequency of ballast water and has a negative correlation with the natural frequency, for small natural frequency of large tank width, the phase lag between roll motion and sloshing moment gets closer to the maximum damping lag of π/2 due to violent sloshing flow.

D-S evidence based FMECA approach to assess potential risks in ballast water system (BWS) on-board tanker ship

Ballast water is essential for cargo ships since it stabilizes vessels at sea. Most ships are equipped with a ballast water system (BWS) to maintain safe operating conditions. This paper attempts to perform a risk assessment for the BWS on-board tanker ship as it poses a major threat to the operational safety of the ship, marine environment, and cargo. To achieve this purpose, the paper utilizes a robust methodology integrating D-S evidence (Dempster-Shafer) theory and FMECA (Failure mode effects and criticality analysis). In the methodology, while the D-S evidence theory introduces a proper mathematical framework to handle epistemic uncertainty in the assessment of risk parameters and to prioritize failure modes as intended, the FMECA is capable of evaluating system potential failures and their causes. Hence, the risk priority number (RPN) can be calculated to assess potential hazards and their consequences in BWS on-board ships. Besides its theoretical insight, the paper contributes to marine safety inspectors, safety researchers, and HSEQ (Health, Safety, Environment, and Quality) managers to identify potential hazards, effects, and consequences in case of BWS failures on-board tanker ships.

Development and application of a new ballast water system for immersed tunnel installation: A case study of the Yuliangzhou tunnel in Xiangyang, China

Ballast water systems are an indispensable part of the installation of immersed tunnels and are utilized to increase or reduce the total weight of immersed tunnel elements in the processes of floating transportation, mooring and sinking. Traditional ballast water systems generally utilize rigid tanks, which consist of retaining walls made of steel-wood parts, for water supply and discharge. However, there are many drawbacks to the traditional ballast water system based on rigid tanks. For example, the construction of rigid ballast tanks is a complex process that is not very efficient and but is very costly. In addition, the processes of installing and dismantling the steel panels of rigid ballast tanks involve substantial welding work and many fire operations, which result in a substantial amount of smoke and dust inside the tunnel elements, resulting in a construction environment that is harmful to human health. Based on the Yuliangzhou Immersed Tunnel, which extends across the Hanjiang River in Xiangyang, China, a new type of ballast water system with flexible water-filled containers was developed to address the abovementioned problems. The equivalent volume method was proposed to determine the geometric size of the flexible water-filled containers. Field stability tests of the flexible water-filled containers were conducted on a 4.8% slope. The experimental results showed that the designed flexible container could meet the actual water demand of tunnel element immersion, without sliding or rolling during water injection, and that the relationship between the water amount and water pressure was approximately parabolic. In view of the specific functions in different installation stages of tunnel elements, the equipment layout of the new type of ballast water system was determined. Based on the processes of tunnel element installation, water supply and discharge technologies were designed. This system has been successfully applied in the Yuliangzhou Immersed Tunnel project, which supports the use of these technologies in immersed tunnel construction.

Analysis on water hammer protection of FPSO ballast water system

In practical engineering, the protection of FPSO water hammer is very important. Through simulation analysis, the relevant data are obtained to provide reference for relevant engineering practice. A general-purpose FPSO ballast water pipe network system was established by aft impulse software, and water hammer simulation calculation and analysis were carried out to find out the maximum pressure position of water hammer phenomenon. According to the water hammer generation mechanism, the simulation research was carried out by two-stage valve closing and adding surge tank into the pipeline. It was found that water hammer was easily caused by quick closing valve; the protection method of two-stage valve closing and installation of surge tank has a very objective protective effect, which provides a reference for related projects.

Ship Energy Saving And Emission Reduction

At present, the energy issue is a common problem faced by all industries. The use of effective energy-saving and emission reduction methods in the shipping process can save the cost of shipping. As the price of oil on ships continues to rise, energy-saving technologies for ship power stations and electrical equipment have attracted widespread attention. The use of energy-saving and emission-reduction technologies can save energy consumption, reduce environmental pollution caused by the shipping process, and obtain both economic and environmental benefits. This article briefly describes the importance of energy saving and emission reduction of ship power stations and electrical equipment on board. It explains the application of specific energy saving and emission reduction methods from the aspects of ballast water system modification, installation of desulfurization system and application of frequency conversion energy saving technology.

Catch me if you can: Comparing ballast water sampling skids to traditional net sampling

With the recent ratification of the International Convention for the Control and Management of Ships' Ballast Water and Sediments, 2004, it will soon be necessary to assess ships for compliance with ballast water discharge standards. Sampling skids that allow the efficient collection of ballast water samples in a compact space have been developed for this purpose. We ran 22 trials on board the RV Meteor from June 4–15, 2015 to evaluate the performance of three ballast water sampling devices (traditional plankton net, Triton sampling skid, SGS sampling skid) for three organism size classes:≥50μm,≥10μm to <50μm, and <10μm. Natural sea water was run through the ballast water system and untreated samples were collected using paired sampling devices. Collected samples were analyzed in parallel by multiple analysts using several different analytic methods to quantify organism concentrations. To determine whether there were differences in the number of viable organisms collected across sampling devices, results were standardized and statistically treated to filter out other sources of variability, resulting in an outcome variable representing the mean difference in measurements that can be attributed to sampling devices. These results were tested for significance using pairwise Tukey contrasts. Differences in organism concentrations were found in 50% of comparisons between sampling skids and the plankton net for ≥50μm, and ≥10μm to <50μm size classes, with net samples containing either higher or lower densities. There were no differences for <10μm organisms. Future work will be required to explicitly examine the potential effects of flow velocity, sampling duration, sampled volume, and organism concentrations on sampling device performance.

ECDIS Possibilities for BWE Adoption

The Electronic Chart Display and Information System (ECDIS) development and implementation have been linked primarily to the safety of navigation. Further development allows the implementation from other aspects of navigation. This primarily pertains to the Harmful Aquatic Organisms and Pathogens (HAOP) from Ballast Water Exchange (BWE) and the use of ECDIS system for improving environmental protection. The paper contains an overview of important legal aspects of sea environment protection related to the Ballast Water Management (BWM) Convention on global as well as on local scale. Apart from enhancing the safety of navigation, integration of the proposed tool for sea environment protection in the ECDIS with onboard ballast water system can significantly contribute to sea and sea environment protection from harmful substances. In this paper, the architecture of such system is suggested. This approach also ensures a reduction of possible consequences on ecological incidents and human errors.

Inactivation of invasive marine species in the process of conveying ballast water using [rad]OH based on a strong ionization discharge

In this paper, invasive marine species in medium-salinity ballast water were inactivated using OH generated from a strong ionization discharge. The OH is determined by the concentration of oxygen active species combined with the effects of water jet cavitation. The results indicated that the OH concentration reached 7.62 μM, within 1 s, which is faster and higher than in conventional AOP methods. In a pilot-scale OH ballast water system with a capacity of 10 m3/h, algae were inactivated when CT value was 0.1 mg min/L with a contact time only 6 s. The viable and nonviable cells were determined using SYTOX Green nucleic acid stain and Flow cytometry. As a result, the OH treatment could be completed during the process of conveying the ballast water. In addition, the concentrations of relevant disinfection by-products (DBPs), such as trihalomethanes (THMs), haloacetic acids (HAAs), and bromate, were less than that required by the World Health Organization's drinking water standards, which suggest that the discharged ballast water posed no risks to the oceanic environment. Nevertheless, for conventional ozonation and electrolysis methods, the ballast water should be treated only in the treated tanks during the ship's voyage and form higher level DBPs.

Reliability Analysis and Optimization of the Ship Ballast Water System

In this paper, the ship ballast water system was considered as an object of study, and the problem to be solved is to improve its reliability. The reliability of the ship ballast water system is improved to a higher level, as it improves the ship's safety,, because it decides the stability, running resistance and also the cargo's safety on the ship. The transportation failure of the ballast water in the ship ballast water system was considered as the top event, thus, a fault tree was established according to the fuzzy set theory, and then the reliability calculation was carried out. Furthermore, the ballast water system was optimized according to the frequent faults occurring in the past, its reliability is calculated again in the same way. The calculated results showed that the optimized ballast water system has a higher reliability value. The core innovation in the study is to solve the problem that involves the uncertainty of randomness and fuzziness by applying a fuzzy number into the fault tree analysis. From the example of reliability analysis of the ship ballast water system, the proposed methods of the application of the fuzzy fault tree theory in reliability analysis is verified effectively.

Reliability Analysis and Optimization of the Ship Ballast Water System

Reliability Analysis and Optimization of the Ship Ballast Water System

The Effect of Rise Angle of V-Hull Non Ballast Ship on Seakeeping Performance

In this paper a new concept in ship design was used to be alternative of ballast water system, to emerge that remedy the introduction of invasive marine species and the disadvantages of ballast water treatment systems. Thus, the hydrodynamic influences due to hull line variation of this kind of ships were studied, using the invariant cross-section area curve under the design draft to change the rise angle at bottom. Then numerical calculation was used to get the seakeeping at each angle. Two 3D models were constructed for 59000 DWT oil tankers and 35000 DWT bulk carriers, where the result of the bulk carrier was exposed.

The Alternatives of Ballast Water System

To eliminate the introduction of invasive marine species and the disadvantages of ballast water (BW) treatment systems a new concept in ship design was developed to be alternative of ballast water system. Non-Ballast ships were rarely mentioned in China even they were studied widely worldwide. In this paper, the different types of non-ballast water ship were reviewed, to be classified in order to facilitate the study of such types of vessels and serve as a base for the development.

The Effect of Rise Angle of V-Hull Non Ballast Ship on Resistance Performance

In this paper a new concept in ship design was used to be alternative of ballast water system, to emerge that remedy the introduction of invasive marine species and the disadvantages of ballast water treatment systems.Thus, the hydrodynamic influences due to hull line variation of this kind of ships were studied, using the invariant cross-section area curve under the design draft to change the rise angle at bottom. Then numerical calculation was used to get the resistance and effective power at each angle. Two 3D models were constructed for 59000 DWT oil tankers and 35000 DWT bulk carriers, where the result of the bulk carrier was exposed.

The Resistance Performance Influences from Hull Line Variation of V-Shaped Non-Ballast Ship (NoBS)

As a New Concept in Ship Design to be Alternative of Ballast Water System, to Emerge that Remedy the Introduction of Invasive Marine Species and the Disadvantages of Ballast Water Treatment Systems. the Non-Ballast Ship has been Studied Abroad, but it is Rarely Mentioned in China. in this Paper, the Hydrodynamic Influences due to Hull Line Variation of this Kind of Ships were Studied, Using the Method of Invariant Cross-Section Area Curve under the Design Draft to Change the Rise Angle at Bottom. then by Using Numerical Calculation, get the Resistance and Effective Power at each Angle.

Assessing changeability under uncertain exogenous disturbance

This paper introduces metrics derived from application of a Markov decision process to evaluate a design’s changeability. Changeability is known to improve product performance if conscientious early-stage design decisions are matched with structured management of the system in response to exogenous disturbances—shifts which may be environmental, market, technological, and political in nature. Included in the paper is a brief discussion of changeability’s role in ensuring strategic product performance as well as a review of past metrics developed, highlighting the open design challenge to more fully capture the managerial and process dimensions inherent to changeability. The proposed metrics are featured in a case study related to the ballast water system of an ocean-going vessel. The result of such application is greater context for the value changeability offers and an improved understanding of the resources required to manage uncertainty over the product’s life cycle.