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Operational problems of ethylene transport by LPG gas carriers

Wieczorek Agnieszka, Giernalczyk Mariusz

Journal of KONES

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2019

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Vol. 26, No. 1

191--197

EN

Ethylene is one of the basic raw materials of the petrochemical industry used for the production of plastics, mainly plastic packaging. The USA is the largest producer of this compound. The enormous increase in demand for Ethylene has been observed in recent years in China as well as in the Middle and Far East. This caused an unprecedented increase in the demand for transport of this cargo by sea. Ethylene carriers for its transport are special construction LPG vessels, having a cascade cycle with Propylene medium (less often the refrigerant R 404 A). They have been designed in such a way as to withstand a working pressure of up to 5.4 bar, and the minimum temperature of the transported load is minus 104⁰C for fully cooled Ethylene. This cargo is explosive in the mixture with air (within concentrations of 2.75-2.6%) and during heating under elevation pressure. Therefore, it is required to transport Ethylene in with an inert gas, most often Nitrogen. During the operation of LPG carriers carrying Ethylene, processes of aeration, inerting, gassing-up, cooling tanks and a cargo are repeatedly carried out. The most problematic to carry is gassing-up operation, because it is associated with significant amounts of Ethylene loss, this causes large financial losses. In the article, the authors attempted to diagnose the most serious problems during carrying out the most important for cargo loss the cargo handling operations.

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Analysis of the possibility of using low speed twostroke dual-fuel engines for propulsion of sea-going vessels

Giernalczyk Mariusz

Journal of KONES

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2019

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Vol. 26, No. 2

45--52

EN

The use of gas/LNG to supply marine engines in addition to tangible economic benefits is also a method of limiting emissions of harmful substances into the atmosphere and meeting strict environmental protection regulations, especially in special areas. The technology of supplying liquid and gas fuels (Dual Fuel) is most easily used in four-stroke engines but the highest thermal efficiency is ensured by combustion two-stroke piston engines. However, in the first two-stroke dualfuel engines, the gas supply installation was more complicated than in the four-stroke engine. It resulted, among others from the necessity of compressing the gas to high pressures (15÷30 MPa), for which extremely energyconsuming multi-stage compression systems were needed. The complicated technical system is inherently prone to failures, which is why the dual-fuel low-speed two-stroke diesel engines remained for a long period in the design and experimental phase. In recent years, there has been a significant breakthrough thanks to the introduction of new solutions with the possibility of supplying two-stroke engines with low-pressure gas (less than 1.6 MPa). In recent years, many ships powered by two-stroke, dual-fuel internal combustion engines were commissioned. Some shipowners owning a fleet of LNG carriers with two-stroke diesel engines that so far have been powered only by liquid fuels have decided to adapt them to gas combustion. This required the adaptation of the engine for gas combustion and the expansion of the supply gas fuel system. This paper is an attempt to analyse the legitimacy of introducing two-stroke, dual-fuel internal combustion engines into the propulsion system and adaptation of engines that are already used to burn gas in them. It presents the changes introduced on one of the LNG gas carriers consisting in adapting the engine to gas combustion through modification of the cylinder head and fuel supply installation. Parameter results of the modified engines obtained during sea trials have been presented. Both advantages and disadvantages resulting from gas combustion have been pointed out. Finally, the possibility of this solution application to other LNG carriers was assessed.

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Ways of adjusting the two-stroke diesel engine to be run on liquefied natural gas

Giernalczyk Mariusz, Łoński Filip, Kaniak Wojciech

New Trends in Production Engineering

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2018

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Vol. 1, Iss. 1

317--324

EN

This article attempts at assessing the feasibility and validity of adjusting the two-stroke diesel engine to be fuelled by liquefied natural gas (LNG). It discusses a set of modifications introduced onto one of the ships carrying liquefied natural gas. These changes consisted in adjusting the engines of the main drive so that they can be fuelled by gas. This has been achieved by the modification of the cylinder head and fuel supply installation. Parameter results of the modified engines obtained during sea trials have been presented. Both advantages and disadvantages resulting from gas combustion have been pointed out. Ultimately, the authors of this article assess the applicability of this solution to other LNG carriers.