Wyniki wyszukiwania - BazTech

1

Optimisation of reliability and maintenance plan of the high-pressure fuel pump system on marine engine

Knežević Vlatko, Stazić Ladislav, Orović Josip, Pavin Zoran

Polish Maritime Research

|

2022

|

nr 4

97--104

EN

This paper presents a method of adjusting and designing the maintenance scheme for the high-pressure fuel pumps of a slow-speed two-stroke marine engine, MAN 6S70MC-C. The maintenance database for the marine fuel system was obtained from the planned maintenance software, and covered a period of 11 years. During this period, 29 failures occurred that required corrective actions. Our methodology includes failure mode analysis, risk analysis, reliability calculation and maintenance interval adjustment. Each failure is described using a failure mode analysis, based on a combination of the mode and cause of failure. The objective of this study is to recommend a new preventive maintenance interval based on the exponential reliability results and the analysed maintenance data. The initial maintenance plan for each fuel pump was set to 8,000 running hours, whereas in the modified plan, it is recommended to set this to 4,000 hours. Our results show an increase in the system reliability from 60% to 95% when the new modified maintenance plan is applied. In addition, the results and the recommended initial maintenance schedule are validated based on three similar types of engine with the same fuel pump system. The new maintenance approach can reduce the risk of component failure, which will lead to increased reliability of the fuel pump system and the optimisation of maintenance costs.

2

LNG market and fleet analysis

Stanivuk Tatjana, Mahić Josip, Stazić Ladislav, Perdić-Lukačević Hana

Transport Problems

|

2021

|

T. 16, z. 4

173--183

EN

This paper is part of larger research on the impact of present and future air emissions from the shipping industry and especially the environmental impact of the rapid spreading of the LNG as a fuel in the industry. Therefore, it was important to gather data related to the LNG market and perform an analysis to gain realistic insight into the market behaviour. This paper analyses the situation and trends of the LNG shipping market over a longer period to predict future developments. Data analysis of the several aspects and patterns of the trade has been performed; the results obtained can enable prediction of the market situation for the future. From the data analysis and predictions of the LNG market, continuous growth in the following years is expected, which linked to an increase of the LNG fleet and number of importing countries. Research has shown that new propulsion alternatives such as MEGI and XDF are appearing on the market as the first choice for new builds, while steam turbines are slowly disappearing. Although market growth is projected from all research parameters, the situation has changed due to the COVID-19 pandemic and its impact on the market. Consequently, growth forecasts will not be realized in 2020.

3

Implementing SimulationX in the modelling of marine shafting steady state torsional vibrations

Vulić Nenad, Bratić Karlo, Lalić Branko, Stazić Ladislav

Polish Maritime Research

|

2021

|

nr 2

63--71

EN

Marine propulsion shafting systems are exposed to torsional vibrations originating from excitations in their prime movers and propellers. It is essential to analyse their steady state response in the earliest stage of ship design. The paper describes the implementation of SimulationX software based upon simulation modelling for these calculations. This software can be used either by the design office of the shipyard or by the classification society for verification within the plan approval phase. Some specifics of the input data preparation are briefly discussed. In addition, the simulation results depend on the modelling approach chosen. For these reasons, the real two-stroke Diesel engine ship propulsion system was chosen and several different models were implemented for system modelling. SimulationX calculation results are compared with those of two well-known and field-proven programs that use an analytical approach. Finally, the results are compared with the measurements performed on the actual newly built ship. Discussion reviews the selected SimulationX model, and its verification and validation in the case of engine cylinders with normal ignition.