MAN Diesel & Turbo has announced the introduction of its Liquid ME-GI (Liquid Gas Injection) engine. The Liquid ME-GI is powered by LPG (Liquid Petroleum Gas), a smaller market than LNG but of significance in certain segments such as the small tankers that ply river traffic and coastal shipping routes.
The Liquid ME-GI is a variant of MAN Diesel & Turbo’s ME-GI engine, whose control and safety system is based on the experience gathered since the mid-1990s at working gas plants, including a 12K80MC-GI-S in Japan, and the development of a VOC (Volatile Organic Compound) engine in the late 1990s. The announcement follows closely on the company’s announcement last autumn that a full-scale type test for its ME-GI concept would take place at its test centre in Copenhagen in 2011.
The Liquid ME-GI engine
All MAN Diesel & Turbo electronically controlled ‘ME’-engine types are available in dual-fuel versions with the LPG-fuelled version designated ME-LGI. The Liquid ME-GI engine’s performance is equivalent in terms of output, efficiency and rpm to MAN Diesel & Turbo’s successful ME-C and ME-B series of engines. As the Liquid ME-GI engine’s fuel system has few moving parts, it is also more tolerant of different fuel types and accordingly can run on DME (DiMethyl Ether).
DME can act as a clean fuel when burned in suitably optimised engines. For example, in Sweden – one of the largest paper manufacturers in the world – it is estimated that DME produced from ‘black liquor’ (a by-product of the pulp-making process) alone could replace 25% of all petrol and diesel consumption. Accordingly, DME displays significant potential as it has the same environmental benefits as LPG, is fully mixable with LPG, and can be produced from biomass.
Generally speaking, LPG-fuelled engines experience safe and reliable running with comparatively low maintenance costs while gas valves and gas pipes are smaller but similar to those of the well-known ME-GI engine.
The Liquid ME-GI engine uses liquid gas for injection all the way from tank to engine and non-cryogenic pumps can be used to generate the required pressure, comprising standard, proven equipment readily available from a large number of suppliers within the LPG industry.
Furthermore, modern, two-stroke diesel engines are superior in fuel efficiency, especially with regard to total operating economy. By introducing LPG as fuel to the dual-fuel GI system, substantial emission benefits can be obtained, especially with regard to SOx and CO2 emissions and particulate matter. NOx emission reductions and Tier-III targets can also be achieved if LPG operation is combined with either an SCR or EGR system. Furthermore, LPG sulphur levels are naturally minimal.
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