An Experimental Study On Urea-SCR System Of Diesel Engine In Order To Lower NO_X Emission

The law of emission is becoming stricter and stricter, for example the ANNEX VI of MARPOL convention make a very strict restriction to the air pollution caused by the ship's exhaust emission, among them, the Regulation 13 established the highest level on the amount of nitrogen oxide exhausts (NOx) in the emission produced by the marine diesel engine, that is, required a very low level of the nitrogen oxide exhausts, in general, handling the exhaust after it's emission is sure to be the only way to this problem. By using the technology called Selective Catalytic Reduction, for short SCR, can greatly reduced the amount of nitrogen oxide exhausts in the exhaust emission and meet with requirement of the law of emission.The study of the method of Selective Catalytic Reduction is, fully considering the producing requirement, not changing the diesel engine's inner structure, not increasing the consumption of oil, and adapting to the considerable low level of nitrogen oxide exhausts emission, used to deal with the exhaust after its emission and control the amount of nitrogen oxide exhausts in the exhaust emission by the diesel engine. In a word, by the experimental study of the SCR, we can get effective scheme for the alteration to the diesel engine in order to meet with the law of emission.The author's research team, on the basis of type 4135G of the diesel engine made in china, develop a technology which is to spray the liquid of urea into the waste pipe and at the same time design a system referred as urea-SCR which use urea as reducing agent .It is very simple to use this system on the diesel engine. There is no need of the any alteration to the diesel structure and the only thing is to install the SCR and the urea-SCR behind the waste pipe. This paper has already made an experiment applied this SCR system to the diesel engine type 4135G and draw a good conclusion.In this paper, the author introduces with detail the general scheme of urea-SCR system, the production of Catalytic, the design of SCR, the trial of bench shelf and the optimist direction of it. The system of urea-SCR is made up of supply system and SCR reactor. It is indicated from the test outcome for theexhaust emission experiment that the system of urea-SCR has obvious effect on the reduction to the NOx emission. Through analyzing the design scheme and experiment result, the author put foreword a kind of optimist direction of the SCR system.