【作者】

Rendler Andre

【摘要】

论文已在上海2013年CIMAC大会上发表，论文版权归CIMAC所有。 In the marine sector a major upheaval is impending. Up to now, in cargo ships, large engines are mostly using heavy fuel oil. In some ports with more stringent emission standards, clean diesel is already used to meet local emission regulations. New upcoming emissions laws will force a decision during the next years, as the required limits for nitro-gen oxides and sulphur oxides (NO, and SOx) are not achievable with the currently used diesel engines running with heavy fuel oil. The use of natural gas (LNG Liquid Natural Gas) becomes more prominent, as the required emission regulations could be achieved moreeasily. A major challenge will be the installation of gas tanks on the ships as well as the handling of refuelling the ships at the harbour. Gas refuelling stations will not be available at every port, which is one of the reasons dual-fuel engines will initially gain in quantity in the shipping industry instead of pure gas engines. Dual-Fuel implies a diesel engine, which can be operated with diesel and gaseous fuel simultaneously. For ignition, diesel pilot injection is used, whereby a small amount of diesel is injected in the intake air-gas-mixture. The main argument and benefit for such a system is the possibility to operate the engine with pure diesel, if no gas is available. Another advantage of using diesel as an ignition method is the high energy content of this fluid. The physical properties of diesel provide the opportunity to ignite lean air-gas-mixtures where common ignition systems have proven useless. For this reason a well-known engine manufacturer and the system supplier for engine management systems, Heinzmann, have jointly developed a dual-fuel engine for direct propulsion ships, whereby both companies will benefit from the extensive experience in diesel engines and controls in marine applications. For this project a diesel engine, specially optimized for dual-fuel operation, is developed. With important features including the optimization of the valve timing, necessary to avoid valve overlapping and therefore flushing losses, special pistons and valves optimized for higher temperatures, special pumps and injectors for small pilot fuel quantities, a safe operation can be ensured with stationary conversion rates of more than95%. For the engine management system, the biggest challenge is the variable engine speed and load combined with the fact that the instantaneous engine out-put torque and power are not known. To ensure high conversion rates, even during dynamic operation, re-quires complex control concepts. In addition, functionalities like switching immediately back to diesel operation are used to avoid problems, such as an ignition failure caused by the pilot injection being too small. To provide a homogeneous air-gas-mixture a venturi gas mixer is used. For gas metering, a gas metering control unit is applied, which regulates the gas flow using physical calculations. With the calculated and measured gas volume flow, a similar linear relationship to the gas-produced power is given, as it is with the diesel fuel rack position and the engine speed. With this data, the combined diesel and gas power can be calculated and the engine can be protected from over-load. Hence this promises to be a suitable system for using gas with engines on maritime applications. Further information, test bench measurements, development milestones and initial experience on maritime test runs will be given on the ensuing presentation.

【会议名称】

第27届CIMAC会议

【会议地点】

上海

【下载次数】

2

返回