Method for operating low-speed marine engine in variable thermodynamic cycle mode

Abstract

The invention discloses a low-speed marine gas engine. When a ship navigates outside an emission control area, the engine works by using fuel oil or fuel gas under the diesel cycle. When the ship navigates in the emission control area, the engine works by using fuel gas under the Otto cycle. Thus, low-temperature homogeneous lean burn is realized, and emission is reduced and meets the third phase of IMO emission standard. The low-speed marine gas engine realizes a variable thermodynamic cycle mode and burning optimization by adopting the combination of various technologies. Fuel gas injection and exhaust timing are adjusted through an electronic control system, and fuel homogeneous premixing is realized through a fuel gas injection valve structure or layout change; the compression ratio is reduced to prevent knocking through a variable valve, and the air-fuel ratio is regulated to realize lean burn through a variable nozzle ring or an exhaust gas bypass technology; and the rated power of the low emission mode of the engine is properly reduced to prevent knocking. By the method, the engine has the advantages of a high pressure gas fuel engine and a low pressure gas fuel engine at the same time.

Description

technical field [0001] The invention relates to an operating mechanism of a marine low-speed gas (including dual-fuel) engine. More specifically, it involves making the engine possess the advantages of Diesel and Otto cycle engines based on variable thermodynamic cycle, and belongs to the field of internal combustion engine combustion organization and emission control. Background technique [0002] At present, there are only two low-speed gas engines in the world, namely, the Danish MAN Diesel&Turbo high-pressure gas engine (that is, the engine using high-pressure natural gas direct injection technology in the cylinder and the Diesel cycle, ME-GI series) and the Swiss Winterthur Gas&Diesel Low-pressure gas engines (i.e. engines using low-pressure natural gas Otto cycle, Flex series). Among them, the gas working pressure of MAN's high-pressure gas engine is greater than 30MPa, and it adopts the Diesel cycle, which has the advantages of high power density, good fuel economy, ...

AI Technical Summary

Problems solved by technology

However, there is no precedent for achieving low-temperature homogeneous combustion in a high-pressure gas engine based on the Diesel cycle, which requires breaking through the inherent thinking that high-pressure gas engines cannot achieve homogeneous lean combustion

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