Reasons for the insufficient atomization combustion of diesel generator sets and improvement methods

The working principle of the diesel generator set explains the working process of the diesel generator set: in the cylinder of the diesel engine, the clean air filtered by the air filter is fully mixed with the high-pressure atomized diesel fuel injected from the injector, and the piston is pushed upward. Pressed, the volume is reduced, the temperature is raised, and the ignition point of the diesel is reached. The diesel is ignited, the mixed gas burns violently, the volume expands rapidly, and the piston is pushed down, which is called work. Each cylinder performs work in a certain order, and the thrust acting on the piston passes through the connecting rod to become a force that pushes the crankshaft to rotate, thereby driving the crankshaft to rotate. Then, the diesel generator injector must have a good atomization state when working, so as to ensure complete combustion of the diesel generator fuel, ensure the normal color of the diesel generator, and ensure the normal power of the diesel generator. What are the causes of poor fuel atomization? In the use, try to avoid the failure of fuel spray and atomization failure.

The process of dispersing the fuel into fine particles is called spraying (or atomizing) the fuel . Spraying the fuel atomized atomization can greatly increase the surface area of ​​the fuel evaporation and increase the chance of the fuel and oxygen contact, so as to achieve rapid mixing. There are many factors affecting the characteristics of the oil bundle, including the structure and size of the injector, the injection pressure, the back pressure of the compressed air in the cylinder, the shape and speed of the fuel pump cam, and the viscosity of the fuel.

(1) Injector structure and size.

The structure of the injector differs, and the internal disturbances that cause the formation of the oil bundle are also different, resulting in different forms of oil bundles. The oil beam is closely matched to the combustion system. Different combustion methods require different types of oil bundles, so different fuel injectors are used.

When the injection pressure and the cylinder back pressure of the compressed air are constant and the total cross-sectional area of ​​the orifice is constant, the number of orifices is increased, and the diameter of each orifice is reduced, and the fuel will be larger when it flows out of the orifice. Throttle, the disturbance in the nozzle increases, so the atomization quality is improved; if the diameter of the nozzle is increased, the core of the oil bundle is dense and the range is increased.

(2) Injection pressure.

The greater the injection pressure of the fuel, the greater the initial velocity of the fuel outflow, and the greater the degree of fuel disturbance in the orifice and the resistance of the compressed air after exiting the orifice, thereby increasing the fineness and uniformity of atomization. That is, the atomization quality is good. When the injection pressure is increased, the range of the oil beam is also increased.

(3) Compressed air back pressure in the cylinder.

When the back pressure of the compressed air in the cylinder is increased, the density of the compressed air is increased, causing an increase in the air resistance acting on the oil bundle, so that the fuel atomization is improved, the spray cone angle is increased, and the range is decreased. In the non-supercharged diesel generator, the back pressure of the compressed air in the cylinder does not change much, so the effect on the characteristics of the oil bundle is not significant.

(4) The shape and speed of the injection pump cam.

When the cam shape is steep or the camshaft speed is high, the fuel supply speed of the plunger of the fuel injection pump is increased. Due to the throttling of the injector orifice, the fuel cannot flow out quickly. As a result, the fuel pressure in the tubing increases, and the velocity of the fuel flowing out from the orifice increases, so that the atomization becomes better, the oil jet range and the spray cone angle are both Increased.

If the combustion of the diesel generator set is insufficient, it will easily cause air pollution. In serious cases, it will endanger the personal safety of the operator. There are some ways to improve the fuel to reduce pollution.

(1) Intake pipe spray

The main function of the intake pipe spray is to absorb heat and dilute the fuel density. When a small amount of water enters the combustion chamber and is well atomized, the oil droplets are broken into smaller oil droplets due to the "microburst" effect of water vapor , thereby promoting the formation and combustion of the mixture, due to the absorption of water during the combustion process. The heat action can lower the maximum combustion temperature. For example, water-oil mixed injection can reduce the fuel density and further reduce the maximum combustion temperature, thus reducing NOx emissions. It should be noted that the winter storage tank of the diesel generator set needs to be anti-freezing, and it is required to automatically adjust the water spray amount according to the load.

(2) Emulsified diesel

In the diesel fuel, the emulsified diesel oil, due to its "emble explosion" effect, makes the fuel atomization good, and promotes the strong turbulence of the air in the combustion chamber, the distribution of fuel and air is more uniform, and the generated soot is reduced. The water gas reaction of water vapor also reduces soot emissions. In addition, emulsified diesel fuel can lower the maximum combustion temperature, so the amount of nox production is reduced.