Test bench runs on a CATERPILLAR 3618 engine have recently been successfully completed for the world’s first dual-fuel conversion on a marine high-speed propulsion engine. The project was initiated by Norwegian shipping line Fred. Olsen S.A. who chose HEINZMANN as a competent and innovative supplier of dual-fuel systems and aquired AVL, a specialist in development of complete powertrain systems, as a partner for executing engine design, simulation, test bed planning as well as for performance and emission development. As part of the GAINN4SHIP INNOVATION Program, the dual-fuel conversion project is co-financed by the European Commission.
The use of LNG in marine applications is becoming increasingly common, insofar it offers a big potential in terms of operating costs and emission reduction. Diesel engines converted to dual-fuel show considerably reduced emissions in case of high conversion ratios. Depending on the emission standard which is required, expensive and unwieldy exhaust aftertreatment systems can become unnecessary or their implementation costs are significantly lower. The engine performance is comparable to gas engines. Against this backdrop, Norwegian shipping line Fred. Olsen S.A. decided upon the dual-fuel conversion of its ferry Bencomo Express by means of HEINZMANN retrofit solutions for marine propulsion engines.
On test bench extensive performance, emission and reliability tests were successfully carried out by AVL followed by DNV-GL approval testing. Fuel consumption was noticeably reduced by the engine efficiency raise in dual-fuel operation. Emissions could be reduced by 30% CO2, 50 % NOx and 90 % SOx at a conversion rate of 90% LNG and 10% MGO.
The dual-fuel conversion was done in a way that the diesel injection system itself was not modified. If necessary, this allows unrestricted diesel operation at any time. The precise multi-point gas admission system is installed as a cost effective “add-on” solution and is based on type approved components in a double-walled configuration.
The dual-fuel system is operated by the latest version of HEINZMANN's MVC 01-24 EFI-controller, actuating the specially developed, double-walled MEGASOL 200 II gas admission valves. This offers very flexible system configuration in order to achieve the best possible adaptation for any application. Together with an intelligent air path management controlled by HEINZMANN’s wastegate valve WG 70, it was possible to operate the engine with a conversion ratio up to 90% gas. As a result the calculations from the comprehensive simulation works executed by AVL were met exactly. The reliable ARIADNE Knock Control System was installed to operate the converted engine at the highest efficiency limits.
Special attention was paid to the transient behaviour of the engine. Also the switch over from diesel to gas and back occurs smoothly and quickly. In case of gas system failure the system returns to diesel immediately.