Study On Turbocharging System And Transient Response Characteristics Of An Oil-Drilling Natural Gas Engine

With the rise of fossil fuel prices and the stringent of the emission regulations,alternative fuel technology grows rapidly.Traditionally,diesel engines are used to provide power on oil-drilling in oil fields.Recently,experiments are made to replace diesel engines with natural gas engines.Results show that natural gas engine has the advantage of smooth running,low noise,low emission and low fuel cost,however,its poor transient response performance makes it unsuitable for oil-drilling work whose load varies rapidly.Therefore,this paper studies the factors that influence the transient response of natural gas engine and put forward an improved solution using 12V190 natural gas engine as an example.Firstly,a simulation model of 12V190 natural gas engine is built using experiment data.Then on this basis,two twin-turbocharger simulation models are built with MPC charging system and pulse charging system.With the twin-turbocharger models,the influence of inertia of turbocharger,type of exhaust system and volume of intake and exhaust pipes on transient response is studied.With the help of low turbocharger inertia,the speed fluctuation rate of the engine under 500 kW loading can be reduced to 7.38% with MPC charging system and 6.46% with pulse charging system and the recovery time can be reduced to 4.73 s and 4.03 s with the two systems.The influence of multiple point injection in the intake manifold on the transient response is studied.Results show that multi-point injection can raise the response performance of the engine.The speed fluctuation rate can be reduced to 3.77% and the recovery time can be reduced to 3.51 s.The influence of load inertia and valve overlap angle on transient response is studied.Results show that adding inertia to the engine can reduce speed fluctuation rate but will raise the recovery time.With the reduce of valve overlap angle,the intake deteriorates and the speed fluctuation rate will raise.The PID parameters of throttle and multi-point injection controller are optimized.After optimization,the speed fluctuation rate can be reduced to 7.08% and the recovery time can be reduced to 4.69 s with MPC charging system.The speed fluctuation rate can be reduced to 6.08% and the recovery time can be reduced to 3.95 s with pulse charging system.With multiple point injection,the speed fluctuation rate can be reduced to 3.07% and the recovery time can be reduced to 3.29 s.Lastly,pulse charging system,multiple point injection and adding load inertia of the engine are used together to improve the transient response of 12V190 natural gas engine.Result shows that by this method,the speed fluctuation rate can be reduced to 3.00% and the recovery time can be reduced to 3.31 s.