•Human reliability analysis for the gas freeing process on chemical tanker ships.•Human error assessment and reduction technique (HEART) based on modified Dempster–Shafer (D-S) evidence ...theory.•Improving safety and human reliability on chemical tanker ships.
Human reliability assessment is vital for most critical shipboard operations such as cargo loading, discharging, purging, gas freeing, etc. on chemical tanker ships since the nature of these processes poses significant threats. There are few human reliability studies particularly applied to shipboard operations in the maritime industry. To remedy this gap, the paper assesses human reliability systematically during the gas freeing process on a chemical tanker ship. To achieve this purpose, an extended HEART d-S (Dempster–Shafer) evidence theory approach is utilised. Although HEART (Human Error Assessment and Reduction Technique) presents a practical human reliability assessment tool, it heavily relies on the judgment of a single rater during APOE (assess proportion of effect). The paper adopts d-S evidence theory to remedy the aforementioned gap since it fuses raters’ opinions. The first novelty of the proposed hybrid method is the use of customized task analysis for shipboard applications within a second-generation HEART d-S evidence method in the maritime industry. Besides its theoretical background, the paper provides practical contributions to maritime safety professionals, chemical tanker ship owners, and safety inspectors to enhance their operational safety and to minimize the probability of human error during the gas freeing process on board chemical tanker ships.
Abstract
At present, the oil of oil fields in remote areas and well sites without petroleum pipeline are mainly transported by oil tankers. Oil will spill and be stolen during the process of ...transportation, resulting in a large difference between the amount of oil loaded at first and the amount of oil unloaded in the end. The traditional method is to measure and print the bill when loading oil, not to re-measure when unloading oil, and to pay according to the bill, which causes great economic loss. Aiming at tackle this problem, this paper designs and realizes a handheld monitoring device and supervision method for the transportation loss of oil tanker. It integrates EEPROM, RTC real-time clock, PCF8563T memory, LED display lamp, LCD1602 display screen and speakers, and communicates and transmits oil quantity information with primary instruments of oil pumping equipment and oil unloading equipment, the information stored by the device can be read by the communication software of the host computer, and the information can be analyzed, calculated and settled accurately by the management software of the host computer. It can effectively prevent oil leakage and oil stealing during transportation.
Oil spill incidents with tankers, port terminals and offshore platforms impact seriously on marine life and socio-economic services. They occur more and more frequently and require immediate and ...effective response which starts with good knowledge of the likely pathways of spilled oil in the region where a pollution has occurred. The drift of a hypothetical oil spill from the main oil port in Peter the Great Bay (PGB) in the Sea of Japan is simulated from a Lagrangian point of view based on the retrospective velocity field of the ROMS circulation model with horizontal resolution of 600 m. The particle-tracking experiments with the effects of oil evaporation and biodegradation have been performed releasing hourly passive tracers at the beginning of every month during a few years. These numerical experiments showed pathways of spilled oil in different seasons, size of the open-sea area covered by the oil and risks of coastline contamination. Three main scenarios of propagation of the spilled oil in the surface layer have been found and analyzed. In the first one, the spilled oil drifts fast away from the coast due to prevailing north/northwest winds in the cold season (from December to April). The second scenario predominantly occurs in the warm season (from May to November) with prevailing south/southeast winds when the oil slick remains near the coast in the first days after an incident. The third scenario is an intermediate one with the dispersal of the spilled oil away from the coast but not too far from the oil spill site. To explain this behavior, we used the Lyapunov maps which allowed us to identify Lagrangian fronts in the study area that shape passive tracer evolution. As a Lagrangian front moves, the oil slick moves with it. At the same time, the front acts as a transport barrier preventing cross-frontal spreading of oil.
•An operational profile based thermal-economic evaluation model is established.•The effect of operating profile on ORC thermal-economic performance is studied.•R123 is suitable for container ships, ...while R365mfc for bulk carrier and tankers.•EPC increased by around 36–41% when operational profile is included.
Escalating crude oil price and environmental problem are attracting more interest in methods to improve thermal efficiency and reduce emission of shipping. Comparatively, The Organic Rankine cycle (ORC) offers a good solution to utilize low-medium quality waste heat from marine engine. In this paper, an operational profile based thermal-economic evaluation model is established providing reliable evaluation on Organic Rankine cycle used for waste heat utilization from marine diesel engines. Base on this model, ORC system is proposed and designed based on the ship’s most typical operational condition. The effect of ship’s operating condition on ORC thermodynamic performance among seven working fluid candidates is analyzed. Thermal-economic analysis is presented with increasing attention to the ship’s operational profile based on the measurement data from 4-week navigation of objective passenger cruise ship. The result indicates that: considering the different thermodynamic properties, R123 is capable of outputting power at heavy load of engine, while R365mfc is more suitable at light load of engine. Taking typical operational profile into consideration, R123 suits better when ORC is designed for container ships, while R365mfc is suggested for bulk carrier and tankers. For the investigated case study, compared with estimation using nominal design output power, the electricity production cost EPC increased by around 36–41% when operational profile is included. Nominally, all working fluid candidates can satisfy 5-year payback limit except RC318. However, only R123, R365mfc and R245ca are feasible when operational profile is considered. This result makes clear that real operational profile is indispensable for assessing the feasibility of technology.
It is of the utmost importance to accurately estimate different ships’ weights during their design stages. Additionally, lightship displacement (LD) data are not always easily accessible to shipping ...stakeholders, while other ships’ dimensions are within hand’s reach (for example, through data from the online Automatic Identification System (AIS)). Therefore, determining lightship displacement might be a difficult task, and it is traditionally performed with the help of mathematical equations developed by shipbuilders. Distinct from the traditional approach, this study offers the possibility of employing machine learning methods to estimate lightship displacement weight as accurately as possible. This paper estimates oil tankers’ lightship displacement using two ships’ dimensions, length overall, and breadth. The dimensions of oil tanker ships were collected from the INTERTANKO Chartering Questionnaire Q88, available online, and, because of similar block coefficients, all tanker sizes were used for estimation. Furthermore, multiple linear regression and extreme gradient boosting (XGBoost) machine learning methods were utilised to estimate lightship displacement. Results show that XGBoost and multiple linear regression machine learning methods provide similar results, and both could be powerful tools for estimating the lightship displacement of all types of ships.
This study focuses on marine accident data regarding accidents that occurred between the years 1998-2010 for ships within the oil tanker category. Data in the study include accident reports, which ...are recorded in the Global Integrated Shipping Information System (GISIS) and country reports. Textual accident data in the GISIS database were tabulated, thus creating a systematic database. By using accident data from this database, a marine accidents map for oil tankers was developed via the ArcGIS 10 program, the areas with the highest accident incident rates were determined, and reasons for oil tanker accidents were revealed through the assessment of factors such as accident type, accident incident number, accident scope, ship tonnage, navigational sea area type, and accident’s impacts on the environment, economy and personnel. The study showed that very high risk areas for oil tanker marine accidents include the Singapore Strait and Oresund, and high risk areas are the Bristol Channel, Suez Channel, Strait of Hormuz, Great Belt, Piraeus, Hull, İstanbul Strait, and Amsterdam, respectively. The study also established that oil tanker accidents are related to ship tonnage and navigational sea area type.
Abstract
In the presented project, a study was made on the propulsion installation on board the LNG tanker with a load capacity of 70,000 dwt. In this regard, all the steps regarding the calculation ...and design of the main elements of this type of installation were followed, such as the propulsion engine, the propeller and the shaft lines. At the end of the shaft sizing stage, a simulation was performed in a specialized software to analyse and verify the evolution of the component elements in an operation scenario.
Ocean-going ships are mostly driven by high‑sulfur heavy fuel oil, which poses public health and environmental concerns. Emission control areas (ECA) have been developed for the regulatory control of ...the sulfur content in fuel. We tracked 28 sample vessels that entered and exited Shanghai Port, to understand how air pollutants, including oxysulfides (SOx), nitric oxide (NOx), and particulate matter smaller than 10 μm (PM10), would change under the ECA regulations. Emission reductions vary with the types and sizes of the ships. In our sample pool, oil/chemical tankers and container ships have the highest decline rates of SOx emissions at 26.8%–56.4% and 17.4%–56.6%, respectively. Cruise ships, container ships, and liquefied gas carriers occupy the highest share ratios of pollutant emissions in the sample pool because of the higher average gross tonnage and correspondingly higher-rated power of the ships' main engines. As expected, SOx and PM10 emissions under hoteling conditions (operations while stationary at dock) can be considerably reduced by switching to low-sulfur fuel. Using fuel with the much lower sulfur content of 0.1% m/m in the ECA, the SOx and PM10 emissions of our sample pool could be reduced considerably by up to 94.4% and 78.3%, respectively, compared to the 0.5% m/m sulfur content used during ship hoteling.
•Emission control areas (ECA) have been developed for regulatory control of sulfur content in fuel.•We tracked 28 vessels to understand how air pollutants would change under the ECA regulations.•Emission reductions vary with the types and sizes of the ships.•Oil/chemical tankers and container ships have the highest decline rates of SOx emissions.•Oxysulfides and particulate matter emissions under hoteling conditions can be considerably reduced with lower sulfur fuel.•ECA regulations are effective and more coastal nations should consider implement a similar scheme.
The minimization and utilization of boil-off gas (BOG) during the production, storage, and transportation of liquefied natural gas (LNG) have drawn wide interests. However, current studies on ...quantification of BOG generation still need to be improved because the mechanical vibration impact on BOG generation has seldom been considered in most of LNG studies. In this paper, the dynamic BOG generation under both heat leakage and vibration impact during the LNG on-road transportation have been quantitatively investigated via the integration of computational fluid dynamics (CFD) and process dynamic simulations. First, a multiphase LNG model is developed to characterize the thermal energy increment due to on-road vibration effect by CFD simulations, where a user-defined function (UDF) is employed with the dynamic mesh algorithm. Next, the vibration-induced thermal energy is introduced into a process dynamic model, where a heat-leakage considered LNG tanker is simulated to quantify the total BOG generation during the LNG on-road transportation. This work for the first time addresses two root causes of BOG generation with both CFD and process dynamic simulations, which lays a solid foundation for future BOG minimization and utilization during various LNG transportation, storage, and applications.
Background
Work on Swedish petroleum tankers before the late 1980s has been associated with an increased risk of hematologic malignancy (HM). Since then, ship modernizations have decreased ...occupational exposure to gases, including the carcinogen benzene. We explored the risk of HMs in Swedish seafarers who had worked on newer types of tankers.
Methods
A case‐referent study in male seafarers from a cohort of all Swedish seafarers was set up by record linkage with the Swedish Cancer Registry using the subjects' personal identification number. For each case (N = 315), five referents were randomly chosen from within the cohort, matched by birth year and three different periods of first sea service (<1985, 1985‐1991, and ≥1992). Information on the type of ship and dates of service was retrieved from the Swedish Seafarers' Registry. Odds ratios (OR) were calculated by conditional logistic regression together with 95% confidence intervals (CI).
Results
The OR of HM was 1.07 (95% CI, 0.80‐1.42) for work on tankers. In seafarers that had started to work on tankers ≥1985, the OR was 0.85 (95% CI, 0.50‐1.43). For those who started to work on tankers before 1985, the OR was 1.17 (95% CI, 0.84‐1.21) and 1.32 (95% CI, 0.86‐2.03) if the cumulative time on tankers exceeded 5 years of service. In this last group, the OR of multiple myeloma was 5.39 (95% CI, 1.11‐26.1).
Conclusion
Although limited by crude exposure contrast and a short follow‐up, work on tankers after 1985 was not associated with an increased risk of HM among Swedish seafarers.
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