How to Maintain Turbocharger of Diesel Generator Set

What are the causes of damage to the diesel generator set turbocharger?

Insufficient lubricating oil or oil supply lag

1. When the turbocharger speed and diesel load increase, the turbocharger oil supply must also increase because the diesel engine is running at high load and the turbocharger speed is high, even if only for a short few seconds. Insufficient oil supply to the turbocharger bearings will also cause bearing damage.

2. When the diesel engine is working under tilt (partial load or full load operation), if the oil level is too low or the air is taken in, the oil pressure will be lowered. Even if the time is short, the supercharger may be damaged due to lack of lubricating oil.

External debris or sediment entering the lubrication system

1. Oils containing dirt or sand have much more wear and damage to the turbocharger bearings than diesel bearings, because the turbocharger's speed is much higher than the diesel's speed. If such damage occurs in the turbocharger, the cause of the oily waste should be found and eliminated, otherwise damage will occur even if the new supercharger is replaced, and the diesel engine may be damaged if it is developed. When the dirt particles mixed in the oil are large enough to block the oil passage inside the turbocharger, the supercharger will be damaged by the lack of lubricating oil. When changing the oil and oil filter, the oil sample in the diesel engine can be extracted for analysis under conditions, which will help prevent the above damage; the oil should be replaced according to the replacement period specified in the instruction manual. The filter must never be extended at will.

External foreign matter enters the intake or exhaust system of the diesel engine

Turbocharger turbines and compressor impellers are rotating at very high speeds. Once foreign matter enters the diesel engine's intake and exhaust systems, the impeller will be damaged; small objects such as sand will erode the impeller. The airflow angle of the blade changes; large and hard objects cause the blade to rupture; soft objects (such as cotton yarn) roll onto the blade in the direction of rotation of the impeller.

If external foreign matter enters and the impeller is damaged, it will damage the entire supercharger and must be replaced completely. Usually, the damage of the compressor impeller is caused by the inclusion of metal pieces in the air filter element or when the filter element is replaced, and the air intake pipe enters the debris, so that it is sucked in by the compressor, if the filter element is not replaced or the intake pipe is not excluded. For debris, it is possible to continue to damage the newly replaced supercharger.

Oxidation or deterioration of lubricating oil

Due to the oxidation and deterioration of the diesel engine oil, the diesel engine oil will form sludge, which will affect the performance and life of the turbocharger.

Operating temperature is too high

In general, the heat source that causes the operating temperature to be too high comes from the gas (exhaust gas) discharged from the engine. If the temperature of the exhaust gas is too high, the supercharger is directly or indirectly damaged. Direct damage, that is, the superheating of the middle case of the supercharger due to high temperature, and corrosion or deformation of the turbine shell material; excessive temperature of the exhaust gas may also cause cracking of the turbine casing. Indirect damage, that is, when the exhaust gas temperature is too high, the extra heat in the exhaust gas will accelerate the turbocharger rotor assembly and operate at a higher than the design speed. If this happens, the compressor impeller will be due to Cracking occurs with one or more repeated high stress loads, and the turbine wheel will also crack due to the material's reduced strength at high temperatures and increased turbine speed. Possible causes of rising exhaust gas temperature are: engine air-fuel ratio is wrong, engine timing is problematic, exhaust gas is throttled, exhaust gas oxygen sensor is faulty, or other engine control systems have problems.

Cleaning and inspection of diesel generator set exhaust gas turbocharger

Exhaust gas turbocharger cleaning

1. Soak the carbon deposits and deposits on the parts in a non-corrosive cleaning solution to make them soft. Among them, the thick carbon deposit on the side wall of the turbine end in the oil return cavity of the middle casing must be completely removed.

2. Use only a plastic scraper or a bristle brush to remove dirt from aluminum and copper parts.

3. When cleaning with steam shock, the journal and other bearing surfaces should be protected.

4. Use compressed air to clean the lubrication channels on all parts.

Inspection of main components of exhaust gas turbocharger

1. Floating bearing

Observe the wear of the end faces of the floating ring and the inner and outer surfaces. Under normal circumstances, the lead-tin layer plated on the inner and outer surfaces after long-term operation still exists, and the outer surface is worn a lot, and the end face of the oil groove is slightly worn, which is normal. The groove drawn on the surface of the floating ring is caused by the uncleanness of the lubricating oil. If the groove is more serious or exceeds the wear limit, a new floating ring should be replaced.

2. Intermediate shell

Observe the presence of scratches and deposits on the back of the compressor impeller and the surface adjacent to the back of the turbine wheel. If there is a phenomenon of friction, the floating bearing has a large wear and the surface of the inner hole of the bearing is damaged, the inner hole or the surface of the inner hole should be ground to remove the traces of copper and lead substances on the surface of the inner hole.

3. Compressor impeller

Check the back of the impeller and the tip of the blade for rubbing, check the blade for bending and breaking. Whether there are cracks at the edge of the inlet and outlet of the blade.

4. Elastic seal ring

Check the wear and carbon deposit on both sides of the working ring of the seal ring; the gap between the thickness of the measuring ring and the free state should be no less than 2mm, if it is less than the replacement.

5. Compressor end gas sealing plate

Check the air seal plate and the middle case at the turbine end of the elastic seal ring seat hole contact area for wear.