LNG fuel compositions can vary globally, which can lead to engine damage and failure. DNV GL has now developed an online PKI Methane Number Calculator to match fuel quality with an engine’s requirements.
The PKI Methane Number Calculator can be applied to a wide range of engine types and used across the entire supply chain by engine manufacturers, ship and truck owners, traders, as well as international policy makers on LNG. It could also support the development of an international standard.
Engine Knock
Engine knock is characterised by auto-ignition of the unburned fuel mixture, known as the end gas, ahead of the propagating flame in the engine cylinder. DNV GL has developed a verified algorithm to quantify the effect of LNG quality on engine knock, and thus to help LNG users ensure safe and efficient engine operations.
The algorithm has been shown to give a significantly more accurate reflection of the impact of variations in fuel quality on engine knock than traditional tools. An extra advantage is that the algorithm can be readily incorporated into an engine-control system to maximize knock-free performance when supplied with a wide range of fuel.
PKI Methane Number
The knock resistance of LNG is characterised by a methane number, similar to the octane number used in gasoline engines. Users of the tool simply enter LNG composition information such as nitrogen, methane, ethane, propane, and n-butane, and the tool calculates a PKI methane number, which can be matched with the engine specification.
Picture: LNG tanker (by Wolfgang Meinhart, Hamburg).
