Control Strategy Of Marine Diesel/Natural Gas Dual Fuel Generator And Experimental Study

With the increasing of environmental pollution and the shortage of petroleum energy,the requirement of the relevant emission laws and regulations to ship emissions is higher and higher,and the development of traditional engine is greatly restricted.Scholars in various countries are actively studying the alternative energy sources of internal combustion engines,abundant natural gas reserves,clean combustion and relatively low price,which is an ideal alternative fuel for diesel oil.The marine mobile power station is mainly based on the diesel generator,which can reduce the emission and reduce the fuel cost,and is an ideal equipment for the power generation.In this paper,6170 diesel engine was converted to diesel / natural gas dual fuel engine,and the development of a control system,so that it can meet the purpose of power generation.The dual fuel engine only needs to install a natural gas supply system on the basis of the original diesel engine,and the mechanical speed governor is changed to the electronic speed governor.The Freescale MC9S12XEP100 microcontroller as Carle micro control chip,developed a set of control system,can control the speed of the engine,pioneered the use of MC33816 chip,to control gas injection valve timing and pulse width,the chip will drive the injection valve function independent of the circuit,and reduce the operation become simple and reliable the burden of MCU.Using the advanced software architecture,according to the hierarchical and modular programming ideas,this paper expounds the methods of speed measurement,timing control,cylinder processing,state identification,MAP management,calibration and communication,and so on.Two kinds of speed control strategies are designed for the load change of the generator and the design of the vehicle.Bench test using a modified dual fuel engine.Measured by the dynamometer simulating station sudden load and sudden load,found that the transient speed was less than the speed of fuel gas speed,but the stable time of long.The dynamic response of fuel gas is relatively good,but there is a problem that the jet pulse width is large,and the speed is not stable enough.At the end of the experiment,the emission of pure diesel fuel and dual fuel is compared,the soot emission of the dual fuel mode is obviously lower,and the NOx emission is similar,but the HC emission is significantly increased.In the medium and high load,the replacement rate is the largest,which can be nearly 80%,which brings a good economic performance.