Experimental Research On Marine Natural Gas/Diesel Dual Fuel Engine

The energy crisis and increasingly stringent environmental requirements have prompted marine engines to use new fuels,in which natural gas is valued by the industry for its high calorific value and abundant reserves.In this context,domestic and international marine natural gas/diesel dual fuel engine has been a certain market promotion,especially the Ministry of transport of China is the dual fuel engine ships have certain policy support.At present,more natural gas/diesel dual fuel engines are used in the inland,offshore and offshore markets,with a small amount of diesel as the ignition fuel,and a large proportion of natural gas is used as the main fuel.This machine can be natural gas and air are mixed with a certain proportion,after the common time period in the intake stroke into the combustion chamber,and about the original diesel engine and diesel consumption of about 20%to 30%of the diesel engine,the compression stroke when injected into the combustion chamber,the combustion of diesel oil in the environment of high temperature high pressure beam,at the same time,the oil equivalent to a large number of fire,ignite surrounding natural gas,which is the engine combustion process.This paper introduces the dual fuel engine with a river basin as the main work of the ship,its parent engine is a mature,bore 210mm,medium speed marine diesel engine,while maintaining the engine configuration under the condition of adding control system,dual fuel gas intake system,and other improvements spare parts.The 210mm dual fuel engine can bore in the two combustion mode(dual fuel mode,pure diesel mode automatic switch).The main contents of this paper are as follows:First,the main structure of the machine compared with the original diesel engine and its working principle in the dual fuel mode are introduced.The ship with dual fuel engine is based on the market share rate of diesel engine is high,adding control system,dual fuel gas intake system,as well as other improved parts.like an explosion-proof door,gas valve etc..Natural gas through the installation of common rail pipe in the upper part of the cylinder cover gas injection valve in each cylinder into the installation on the cylinder head and large flow of natural gas,the natural gas injection valve can also be realized according to the set time to open or close.The controller through multiple sensors to determine the operating state of the engine,calculating and analysis to the executive device issued a directive,the natural gas is sprayed into the intake manifold of the cylinder head in the intake stroke timely enough,and mixed with air into the combustion chamber.Second,to develop an engine,a large number of verification tests are necessary,such as ship propulsion characteristic test,power load characteristic test,exhaust emission test,whole machine endurance test and so on.After a large number of experiments,the engine power performance and fuel consumption of original machine,cost is lower than that of diesel engine,NOx and particulate emissions than diesel dual fuel engine;it can be said that this can completely replace the diesel engine as power.Third,the combustion mode of both diesel engine side injection characteristics while burning,also contains a gasoline engine spark ignition combustion characteristics of dual fuel engine is ignition spark ignition energy than Saido,more.But in the process of matching calibration,technicians discovered the problem that the explosion pressure of this engine is too high.In order to solve this problem,this paper describes how the gas intake system,gas control system,fuel system and other aspects,to develop a variety of programs,a large number of tests were conducted,eventually the engine to meet the design requirements.