• Research,
  • PhD,

LHEEA's mini-seminar - 24 May 2018

The LHEEA organizes mini-seminars every Thursday at 1.45pm in the distance-learning room. Open to all!

On May 24, 2018 from 13:45 To 14:30

This week, Jonas THIAUCOURT, TSM team PhD will presnt his work on:

"A MODEL LIBRARY FOR LNG FUEL SYSTEMS ON-BOARD"

In the light of ever-tightening emission regulations, NG (Natural Gas) is perceived by ship-owners as a clean burning, available and affordable fuel choice. NG is a mixture of mainly methane with other hydrocarbon species, nitrogen and trace compounds. To save space, NG can be stored on-board in cryogenic tanks under its liquid form called LNG (Liquefied Natural Gas). The presentation will focus on type C cryogenic tanks designed to withstand pressure. Despite its insulation system, heat leaks into the reservoir. If the consumption is null or low such as at berth or anchorage, the pressure in the tank rises. In order to minimize risks to the ship, its crew and the environment, tank rupture by
overpressure should be prevented by a Pressure Relief Valve (PRV).

Still, venting of fuel vapor is not acceptable except in emergency situations. To avoid such cases, the International code of safety for ships using Gases or other low-flashpoint Fuels (IGF CODE –
entered into force in 2017) sets requirements for the tank’s loading limit and holding time. Pressurization rate, like specific consumption, is linked to the gas’ quality. LNG from different regions, undergoing various ashore treatments, have diverse compositions. Moreover, the uprising of
renewable energy favors new players such as synthetic gas or hythane (a mixture of hydrogen and natural gas), redefining the properties of tomorrow’s NG as a fuel for ships [1]. Hence, gauging the effects of composition is an issue for better compliance and sharper techno-economic analysis.

A homogeneous thermodynamic model has been developed (mini seminar 1). In this presentation, the model is used in parallel with regulation expectations to ensure compliance (IGF code). Then, the impact of composition, loading level and ambient temperature is evaluated. Quality affects the loading limit, leading to a variation in the carried energy up to 57.1 MMBTU for a 40 ft. LNG
tank container. The ambient temperature and the level at service pressure alter the holding time more than the composition.

[1] W. Müller and R. Jens, “Variation of Natural Gas Composition Challenges for Power Generation CIMAC Circle Presentation,” 2014.

Published on May 23, 2018 Updated on May 23, 2018