油田柴油机混合气燃烧过程流动模拟及排放污染研究

发布时间：2018-05-17 01:41

本文选题：油田增压柴油机 + 参数的模拟　；参考：《东北石油大学》2015年硕士论文

【摘要】：在大庆油田,带动钻机的动力是柴油机,大型工程车辆动力是柴油机,很多汽车的发动机也是柴油机。柴油机以其优越的燃油经济性、动力性和可靠性得到了越来越广泛的应用。由于柴油机使用的燃料普遍是碳氢化合物燃料,当它在燃烧室内完全燃烧时,将只产生二氧化碳和水蒸气,但在柴油机的实际运行时,尤其是油田使用的大功率柴油机,转速很高,燃料的燃烧过程时间很短,燃料与空气不可能混合地完全均匀,燃料的氧化反应就不够完全,将直接导致不完全燃烧产物的生成。如：一氧化碳(CO)和碳氢化合物(HC)和氮氧化合物(NOx)。从而造成了严重的空气污染。为了减少最具毒性的氮氧化合物的排放,采取措施来改善排放污染,使柴油机排放污染最小,是我们急需解决的问题。本文是以油田使用的增压柴油机为例,通过GT-Power软件建立模型对油田常用增压柴油机进行研究,并把油田增压柴油机的仿真结果与实验结果进行对比,然后设计几种不同尺寸的文丘里管,进行试验,筛选出不同的参数,同时再改变废气再循环的控制阀门的开度,在不同的喷油时间发生改变时,对各参数的变化加以研究,找出柴油机的排放、经济型、动力性等随参数变化的结论。从试验结果来看,当柴油机的喷油提前角增大时,其功率、扭矩就会呈增加的趋势,而氮氧化合物就会越来越多。当废气再循环EGR阀开度增大时,废气再循环比率(EGR率)也会增加,氮氧化合物的排放就降低。然后再利用STAR-CD技术,对油田增压柴油机进行仿真模拟,不但要研究柴油机燃烧室内混合气的压力温度的分布、流速的变化,柴油浓度的变化和排放的废气(主要是废气中氮氧化合物)的生成等。而且,还要研究柴油机喷油器喷孔的大小(主要是直径的变化),燃烧室结构的不同,混合气在压缩过程中涡流强度的变化等对增压后柴油机燃烧过程的影响,对氮氧化合物(NOx)排放的影响等。通过实验发现：当柴油机燃烧室内活塞顶面的凹凸结构的形状会导致混合气的涡流变化不均匀,使柴油机喷油器的各个喷孔喷出的油束在燃烧室内与空气的混合的不均匀时,也会使燃烧效果不好。当柴油机混合气的涡流较大时,喷油器喷射的油就会存在活塞顶面的凹凸里,向外传播很困难,使得气体混合不好,排放的废气中氮氧化合物(NOx)增多。
[Abstract]:In Daqing Oilfield, diesel engine is the driving power of drilling rig, diesel engine is the power of large engineering vehicle, and the engine of many cars is diesel engine. Diesel engine is more and more widely used for its superior fuel economy, power performance and reliability. Since the fuel used in a diesel engine is generally a hydrocarbon fuel, when it is completely burned in the combustion chamber, it will only produce carbon dioxide and water vapor, but in the actual operation of the diesel engine, especially the high-power diesel engine used in the oil field, The combustion time of the fuel is very short and the fuel and air can not be mixed completely. The oxidation reaction of the fuel is not complete, which will lead to the formation of the incomplete combustion product directly. For example: carbon monoxide (CO) and hydrocarbons (HCC) and nitrogen oxides (nitrous oxide). This caused serious air pollution. In order to reduce the emission of the most toxic nitrogen oxide, it is urgent to solve the problem that we should take measures to improve the emission pollution and minimize the emission pollution of diesel engine. In this paper, the supercharged diesel engine used in oil field is taken as an example, and the model of supercharged diesel engine is established by GT-Power software, and the simulation results of supercharged diesel engine in oil field are compared with the experimental results. Then several Venturi tubes of different sizes are designed, and different parameters are screened out. At the same time, the opening of the control valve of exhaust gas recirculation is changed, and the change of each parameter is studied when the fuel injection time changes. To find out the diesel engine emissions, economic, power and other changes with the parameters of the conclusion. The experimental results show that when the fuel injection advance angle increases, the power and torque of the diesel engine will increase, while the nitrogen oxygen compounds will be more and more. When the opening of exhaust gas recirculation (EGR) valve increases, the exhaust gas recirculation ratio (EGR) also increases, and the emission of nitrogen oxides decreases. Then using STAR-CD technology to simulate the supercharged diesel engine in oil field, not only the pressure temperature distribution and the velocity change of the mixture in the combustion chamber of the diesel engine should be studied. The change of diesel fuel concentration and the formation of exhaust gas (mainly nitrogen and oxygen compounds in exhaust gas) etc. Furthermore, the influence of the size of the injection hole (mainly the change of the diameter, the structure of the combustor, the swirl intensity of the mixture in the compression process) on the combustion process of the turbocharged diesel engine should be studied. The effect on nitrous oxide (no _ x) emission and so on. The experimental results show that when the shape of the concave and convex structure of the top surface of the piston in the combustion chamber of the diesel engine will lead to the non-uniform variation of the swirl of the mixture, the fuel jet from the injection holes of the diesel engine injector will be mixed inhomogeneously between the combustion chamber and the air. It also makes the combustion ineffective. When the swirl of diesel engine mixture is larger, the fuel injected by the injector will have concave and convex on the top of the piston, which makes it difficult to spread out, which makes the gas mixing bad, and the nitrogen and oxygen compounds in the exhaust gas increasing.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X741;TQ511.1

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