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Notice! Running a diesel generator set at low load will generate these danger signals!
June 06, 2022
Many users often have a serious misunderstanding, thinking that the smaller the load of the diesel generator set, the better. In fact, this is very wrong. The reasonable range of running the diesel generator is about 60-75% of the maximum rated load. When the diesel generator set regularly reaches or is close to full load, short-term low-load operation is allowed.
Many users often have a serious misunderstanding, thinking that the smaller the load of the diesel generator set, the better. In fact, this is very wrong. The reasonable range of running the diesel generator is about 60-75% of the maximum rated load. When the diesel generator set regularly reaches or is close to full load, short-term low-load operation is allowed. Running a diesel generator set at low load will generate 3 danger signals, let's take a look at them together.
1. Poor combustion
Poor combustion can cause soot formation and unburned fuel residue to clog and clog piston rings (in reciprocating engines, in this case generators, piston rings are split rings that fit into grooves in the outer diameter of the piston). This creates hard carbon that causes the injectors to become clogged with soot, resulting in worse combustion and black smoke. Condensed water and by-products of combustion often evaporate at higher temperatures, forming acids in the engine oil, which only further complicates the problem. Unsurprisingly, this results in slow but extremely harmful wear on the bearing surfaces.
The normal maximum fuel consumption of the engine is about half of that at full load. All diesel engines must run above 40% load to allow complete combustion of the fuel and to operate the engine at the correct cylinder temperature. That sounds about right, especially during the first 50 hours of the engine running.
2. Carbon deposition
The generator's engine relies on sufficient cylinder pressure to force the piston rings to seal tightly in the bore (the diameter of each cylinder) to resist the oil film on the bore surface. So-called "inner glass" is created when hot combustion gases blow through poorly sealed piston rings, causing what's called a "flash burn" of the lubricating oil on the cylinder walls. This creates an enamel-like glaze that removes the intricate patterns designed to hold oil and return it to the crankcase via the oil scraper ring.
This harmful cycle can cause irreversible damage to the engine and may result in the engine not starting and/or not reaching maximum power when needed. After oil or carbon deposits have occurred, the damage can only be repaired by: removing the engine and re-boring the cylinder bores, machining new honing marks and removing, cleaning and removing the carbon deposits from the combustion chamber, injector nozzles and values . As a result, this usually results in higher fuel consumption, which results in more carbonized oil or oil residue. Carbonized oil is engine oil that is contaminated with carbon deposits, which occurs naturally when the engine burns fuel, but excess carbonized oil occurs when the piston rings get stuck and the cylinder bores become slick.
Three, produce white smoke
Running generators at low loads can cause white smoke, which is produced from exhaust gases with higher hydrocarbon emissions due to cooler temperatures (because the fuel is only partially combusted at that temperature). White smoke is produced when diesel fuel does not burn properly due to lack of heat in the combustion chamber, which also contains small amounts of harmful toxins, or when water leaks into the air intercooler. The latter is usually caused by a burst cylinder head gasket and/or a cracked cylinder head. As a result, the percentage of unburned fuel in the oil increases because the rings, pistons and cylinders cannot expand enough to ensure a good seal, which in turn causes the oil to rise and then exit through the exhaust valve.
When the generator set is used under a load of less than 30% of the maximum power value, other problems that may occur are:
Excessive wear on the turbocharger
Turbocharger housing oil leak
Increased pressure in the gearbox and crankcase
Cylinder liner surface hardening
The exhaust gas treatment system (ATS) is less efficient and may initiate a forced regeneration cycle of the DPF.
Long-term low-load operation of the diesel generator set will also lead to increased wear and tear of the running parts of the set and other consequences that will deteriorate the engine, which will lead to the overhaul period of the diesel generator set. Therefore, in order to prolong the service life of the diesel generator set and better play its function, Users should pay attention to proper operation and maintenance to reduce low load runtime.
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