Diesel generator maintenance training diesel article -p44-p47 diesel engine booster system

Diesel generator maintenance training diesel article -p44-p47 diesel engine booster system

Third, diesel generator diesel engine booster system

The purpose of boosting the diesel engine diesel engine is to increase the intake pressure so that the diesel engine can increase the intake density without changing the working volume of the cylinder, increase the intake air volume in the cylinder, and burn more when the mechanical strength allows. Fuel to increase diesel engine output. Compared with non-supercharged diesel engines, supercharged diesel engines can generally increase their power by about 60%. The fuel consumption can be reduced by about 5.5%, and exhaust emissions can also be purified.

At present, foreign large and medium-sized diesel engines and some domestic diesel engines are equipped with turbochargers, and some have intercoolers installed between the compressor and the intake pipe of diesel engines. The purpose is to further increase the power and reduction of turbocharged diesel engines. Diesel consumption rate. Tests have shown that when the intake pressure exceeds 2stm (2.0265X10 5th power Pa), the intake air density decreases with the increase of the intake pressure. Pressurized intake air is affected by higher compression work, and the temperature is higher. Therefore, in many diesel engines, an air cooler is installed at the air outlet of the compressor to reduce the intake air temperature, thereby increasing the air intake density. The purpose is to further increase the power of turbocharged diesel engines.

There are generally three types of diesel generator diesel engine driven instruments: exhaust turbocharger, supercharger and regenerative booster.

At present, exhaust gas turbochargers are used more often, and exhaust gas turbochargers are divided into two types: radial flow and axial flow.

Due to the simple structure, high efficiency and small moment of inertia of the radial exhaust gas scrambler, the turbocharger for the diesel engine is generally selected to be a radial exhaust turbocharger.

1, diesel generator radial exhaust turbine structure

The physical appearance of the radial exhaust turbocharger is shown in Figure 2-53. The radial exhaust turbocharger consists of a turbine, a compressor and an intermediate shell. The basic principle is that the high-temperature and high-pressure exhaust gas discharged from the exhaust pipe of the diesel engine is guided by the turbine shell and evenly enters the nozzle ring in a radial direction. After the exhaust gas enters the nozzle, the pressure energy of the exhaust gas is converted into kinetic energy, and is rushed toward the turbine wheel with a relatively high gas pressure, so that the impeller rotates at a high speed.

The physical shape of the turbine section is shown in Figure 2-54. The scour wheel is mainly composed of a turbine shell, a nozzle ring, a turbine impeller and a main shaft. Its role is to use exhaust energy to convert thermal energy into mechanical energy, and the high speed rotation of the impeller on the compressor is driven by the main shaft.

The physical shape of the compressor section is shown in Fig. 2.55. Compressor is mainly composed of impeller, suction shell and compressor shell. Its function is to convert the mechanical energy transmitted from the scourer into the potential energy of air, and transport compressed air with a certain pressure into the intake pipe of the diesel engine.

The physical shape of the middle shell part is shown in Figure 2-56. The middle shell of the turbocharger functions as a bracket and a connection between the scrambler housing and the compressor, and the two ends are respectively fastened with the screw housing and the turbine housing and the compressor housing. The water inside the middle shell is suitable for cooling the shell and bearings. Both ends of the shell are respectively mounted with bearings for supporting the main bearings.

The oil pipe from the oil filter to the booster intermediate casing is the oil inlet pipe, and the other report pipe is then the return oil pipe. Lubricating oil is added to the casing to lubricate the bearings at both ends.

2. Diesel generator exhaust gas turbocharger prone to failure and causes

During use, the turbocharger of the exhaust gas wheel is prone to depressurization pressure drop, etc. The causes of the failure are:

Excessive pressure and abnormal sound

1 Turbocharger booster pressure drop will lead to diesel engine power shortage and diesel consumption increase, there will be exhaust pipe black marriage phenomenon. The causes of these failures are generally due to the dirty air filter cartridges, too much debris on the air passages of the compressor and the impeller, excessive carbon deposition on the turbine blades of the turbocharger or between the shaft and the seal ring, and the pressurization. Damage to individual parts etc.

9 The supercharging pressure of the supercharger will increase the temperature of the exhaust gas and cause the rotating speed to exceed the rated speed. The cause of this failure is generally an exhaust valve leak or an excessive diesel fuel feed advance angle.

2 The reason that the supercharger has abnormal sound during use is generally the oil in the middle housing of the supercharger. 3. Troubleshooting method The supervising method for supercharging supercharging pressure drop is as follows; 1 Start with the easy-to-check part. First remove the air filter element. If there are many impurities, clean the filter element.

2 Disassemble the turbocharger according to the technical requirements, then clean the removed parts in gasoline. The carbon deposits to be attached to the parts (such as the blades of the scorch, the scourer shell, the nozzle ring, etc.) are softened and then removed with a wooden spatula.

9 Gasoline cleansing of compressor air passages and impurities absorbed by the impeller. Before the supercharger is assembled, it is necessary to perform a dynamic balance test on the group. In one case, the unbalanced eccentricity should be less than 0.0012 mm.

The overcharge pressure of the diesel generator booster is overhauled as follows:

1 Check cylinder pressure with cylinder pressure gauge.

2 Check the fuel supply advance angle of the diesel engine.

2 If the exhaust valve has a large number of hinges, remove the cylinder head and check the quality of the exhaust valve and the seal of the exhaust valve and valve seat. When the quality of the exhaust valve is good and the seal is not strict, the valve should be ground with abrasive sand. Until the requirements are met, proceed with assembly.

The method for repairing the abnormal sound of the diesel generator booster is as follows:

1 Check the oil pressure of the diesel engine. Under normal conditions, the booster's oil pressure is generally higher than that of a non-supercharger. If the technical requirements are met, check the quality of the oil.

2 Disassemble the supercharger, check the bearings and other military parts in the middle shell, and replace the more serious parts in time.