Optimization design of marine seawater desulfurization technology

Because ships burn inferior fuel, the emission of ship exhaust gas has a great impact on the environment. In order to effectively deal with the increasingly strict limit of sulfur content and SO2 emission of ship fuel by the International Maritime Organization. On the basis of analyzing the characteristics of SO2 gas soluble in seawater, this paper studies and compares the current industrial seawater desulphurization technology and other flue gas desulfurization technologies, puts forward the feasibility of the application of seawater desulphurization technology in the exhaust gas emission of marine diesel engine, and theoretically designs and calculates seawater desulphurization technology is pointed out.

Modeling and performance analysis of diesel engine considering the heating effect of blow-by on cylinder intake gas

Recently, the stringent international regulations on ship energy efficiency and NOx emissions from ocean-going ships make energy conservation and emission reduction be the theme of the shipping industry. Due to its fuel economy and reliability, most large commercial vessels are propelled by a low-speed two-stroke marine diesel engine, which consumes most of the fuel in the ship. In the present work, a zero-dimensional model is developed, which considers the blow-by, exhaust gas bypass, gas exchange, turbocharger, and heat transfer. Meanwhile, the model is improved by considering the heating effect of the blow-by gas on the intake gas. The proposed model is applied to a MAN B&W low-speed two-stroke marine diesel engine and validated with the engine shop test data. The simulation results are in good agreement with the experimental results. The accuracy of the model is greatly improved after considering the heating effect of blow-by gas. The model accuracy of most parameters has been improved from within 5% to within 2%, by considering the heating effect of blow-by gas. Finally, the influence of blow-by area change on engine performance is analyzed with considering and without considering the heating effect of blow-by.

Diagnosing the state of marine diesel engines by probabilistic fault recognition method

Diagnostics of marine diesel engines, during the navigation of the vessel, allows you to prevent the development of an accident, perform maintenance in a timely manner, eliminate the possibility of technical failures. The wear of parts is one of the main reasons for putting a diesel engine into repair. Timely detection of the occurrence of wear according to the indications of standard monitoring devices, allows you to prevent the negative consequences of wear, perform repairs in a timely manner, eliminate the possibility of an unplanned exit of the marine diesel engine from operation. If there is a need to operate a marine diesel engine in conditions different from those established by the manufacturer, diagnostics allows you to predict the temporary operational characteristics

NUMERICAL STUDY ON NOX EMISSION REDUCTION MECHANISM OF HCCI MARINE DIESEL ENGINE FOR IMO TIER III EMISSION LIMITS

With the advantages of ultra-low emissions of oxides of nitrogen (NOX) and high thermal efficiency, the homogeneous charge compression ignition (HCCI) mode applied to marine diesel engine is expected to be one of the technical solutions to meet the International Maritime Organization (IMO) MARPOL73/78 Convention-Annex VI Amendment Tier III requirement. According to the NOX chemical reaction mechanism, taking a marine diesel engine as the application object, the numerical study on the NOX formation characteristics of n-heptane for HCCI combustion process is performed. The results indicate that NO is usually the main component in the generation and emissions of NOX with the n-heptane HCCI mode. The combustor temperature plays more important role in the proportion of NO generation and emission. Compared with the experimental data of conventional marine diesel engine, the emission reduction rate of NOX can achieve an average of more than 95% in using HCCI technology.

INTERVAL-VALUED INTUITIONISTIC FUZZY TOPSIS-BASED MODEL FOR TROUBLESHOOTING MARINE DIESEL ENGINE AUXILIARY SYSTEM

In this paper, we present an interval-valued Intuitionistic Fuzzy TOPSIS model, which is based on an improved score function for detecting failure in a marine diesel engine auxiliary system, using groups of experts’ opinions to detect the root cause of failure in the engine system and the area most affected by failures in the diesel engine. The improved score function has been used for the computation of the separation measures from the intuitionistic fuzzy positive ideal solution (IFPIS) and intuitionistic fuzzy negative ideal solution (IFNIS) of alternatives while the criteria weight have been determined using an intuitionistic fuzzy entropy. The study is aimed at providing an alternative method for the identification and analysis of failure modes in engine systems. The results from the study show that although detection of failures in Engines is quite difficult to identify due to the dependency of the engine systems on each other, however using intuitionistic fuzzy multi-criteria decision-making method the faults/failure can easily be diagnosed.

Combustion Fault Simulation of Diesel Engine Based on AVL-FIRE Software

Marine diesel engine is developing towards the direction of precision, automation and systematization, and it has the characteristics of complex structure and many parts. If it breaks down, it will affect the operation safety of the whole ship. If it is serious, accidents may occur, which may cause maritime accidents. Therefore, how to prevent the occurrence of marine diesel engine failure and analyze the cause of failure after the accident has been paid more and more attention by scholars at home and abroad. In the simulation study of the working process of diesel engine, for different types of diesel engines, the laws of combustion process are different, even for the same diesel engine in different working conditions, the combustion laws are also different, which will cause great difficulties to study the combustion process. Using computer simulation technology, the physical calculation model of diesel engine system is established by simulating the typical combustion faults of marine diesel engine. AVL-FIRE software is used to simulate different faults of diesel engine combustion process, and the changes of various performance parameters of diesel engine under corresponding faults are obtained, so as to grasp its working state macroscopically, and provide relevant basis for the design, optimization and operation management of diesel engine system.

Theoretical assessment of the stress-strain state of the cylinder sleeve of a marine diesel engine from the effects of variable moving gas loads

Цилиндровые втулки относятся к наиболее нагруженным деталям судовых дизелей. Оценка их напряженно-деформированного состояния показывает, что последовательное форсирование дизелей по среднему эффективному давлению требует существенного пересмотра некоторых положений конструирования этих деталей. Это касается конструктивного оформления наружных поверхностей втулок, а также их закрепления в блоке цилиндров. В статье рассматривается влияние условий закрепления верхнего торца втулки и промежуточных опор-уплотнителей на деформирование цилиндровой втулки газовыми нагрузками. Показано, что для выбора оптимального места установки кольца-уплотнителя по длине втулки целесообразно исходить из минимизации воздействий на него со стороны подвижных газовых нагрузок. Предлагается расчётная методика, которая позволяет определить то место установки промежуточной опоры, где она практически не влияет на параметры напряженно-деформированного состояния цилиндровой втулки судового дизеля с учётом особенностей закрепления её верхнего торца в цилиндровом блоке. Применение данной методики позволяет с учётом особенностей конкретного двигателя обоснованно решить вопрос размещения дополнительных опор-уплотнителей. Cylinder bushings are among the most loaded parts of marine diesel engines. Evaluation of their stress-strain state shows that the sequential forcing of diesel engines according to the average effective pressure requires a significant revision of some provisions for the design of these parts. This applies to the design of the outer surfaces of the bushings, as well as their fastening in the cylinder block. The article examines the influence of the conditions for fixing the upper end of the sleeve and intermediate support-seals on the deformation of the cylinder sleeve by gas loads. It is shown that in order to select the optimal place for installing the seal ring along the length of the sleeve, it is advisable to proceed from the minimization of the effects on it from the movable gas loads. A calculation method is proposed that allows you to determine the place of installation of the intermediate support, where it practically does not affect the parameters of the stress-strain state of the cylinder liner of a marine diesel engine, taking into account the peculiarities of fixing its upper end in the cylinder block. The use of this technique allows, taking into account the characteristics of a particular engine, to reasonably solve the issue of placing additional support-seals.