Analysis of the causes of black smoke from diesel generators
Since black smoke is the product of incomplete combustion of fuel, the main cause of black smoke is fuel. Caused by defects in the combustion assembly and defects in the intake and exhaust systems. The reason why diesel generators emit black smoke is that when the oil that lightly enters the cylinder of the diesel generator is burned, it decomposes at high local temperatures and lack of oxygen, and dehydrogenates into tiny particles solids with carbon as the main component. It is the product of incomplete combustion. It is generally expressed in terms of smoke and its unit is the BSU (Bosch). Therefore, whether it is the fuel system, combustion system, or intake and exhaust system, any factor affecting the entire combustion can cause smokeblack.
(1) The atomization of the fuel injector is poor, the oil particle size is uneven or too large, and it cannot mix well and evenly with air. Local areas lack oxygen during combustion and crack. at high temperature, thus producing a black cigarette. Tests have shown that when a cylinder has poor atomization, even if the fuel consumption increases by only 0.1%, the smoke level can reach 4BSU.
(2) Abnormal injection of the fuel injector (including secondary injection, alternating injection, multiple injections or dripping) will cause fuel injection into the cylinder to continue after that the cylinder is on fire. the fuel burns at high temperature and lack of oxygen, so it is easy to produce black smoke.
(3) The fuel supply to the individual cylinders is too great or the generatordiesel is overloaded because there is too much fuel in the cylinder, a lack of air and a lack of oxygen in the combustion, resulting in. black smoke. In fact, this is also the reason why black smoke is caused by pulling the cylinder and holding the shaft. At this point, the friction work of the diesel generator is greatly increased. Only by increasing the operating capacity of the cylinder can the same large effective work be produced. This also equates to overloading the diesel generator, resulting in emissions. black smoke.
(4) The quality of diesel does not meet the requirements, especially the cetane index is too low, which worsens the ignition performance of the diesel generator and the combustion delay will increase later , causing black smoke. .
(5) Deformation of the inner hole of the high pressure oil pipe will cause changes in capacityflow rate and pressure of the oil pipe, thereby causing secondary injection of the injector and affecting the atomization quality: the piston of the fuel injection pump wears out. The oil outlet valve. Significant wear leads to a reduction in pressure in the oil pipe, thus deteriorating the atomization quality of the injector. All this results in incomplete combustion of fuel, high local temperatures and lack of oxygen, causing black smoke.
(6) There are some requirements for the height of the injector of Cummins series diesel generators extending out of the cylinder head plane, which is 2.4-3.0mm if the gasket is incorrect during disassembly and assembly. process, it will cause oil. The distance between the cylinder head and the cylinder head plane is too large or too small, which will not ensure that the mist spray torque matches the shape of the combustion chamberion. It will either be sprayed on the combustion. the chamber wall or lower plane of the cylinder head, causing a local fuel leak. It cannot be well contacted and mixed with air, causing local high temperature and lack of oxygen producing black smoke.
(7) An important condition for the combustion of diesel generator is that the cylinder must have a certain compression pressure and a certain compression temperature. When the piston ring seal and valve seal are bad, the compression pressure in the cylinder is insufficient, resulting in insufficient combustion and black smoke.
(8) The function of the ventilation system of the diesel generator is to According to the operating conditions of the diesel generator, fresh air is supplied to the diesel engine regularly and quantitatively, and the exhaust gas is discharged . When the air filter is clogged, the compressor is obstructedfaked, the intercooler is clogged, the exhaust silencer is clogged or the manifold pressure is insufficient due to compressor failure, the amount of air entering the cylinder of the diesel generator is insufficient, resulting in combustion failure. Lack of air, high temperature and lack of oxygen produce black smoke.
(9) Improper gas distribution phase can not only cause insufficient air intake and poor exhaust from the diesel generator, but also change the intake and exhaust patterns, thereby affecting normal ventilation and combustion of the diesel generator. , causing black smoke.
Troubleshooting:
According to convention, it is generally believed that the Cummins diesel generator oil system is caused by air, blockage or loose seal, but when This is the specific For diesel generators, maintenance personnel mustfirst check the oil system, filter elements and other related components, and find no leaks or engine blockages; check fuel pump, fuel injectors, etc. and find no problem further; Valve clearance, injection advance angle, etc. of the diesel generator were checked and adjusted, but the fault still existed.
Analysis of the causes of failure:
Then the technical staff analyzed that the check valve of the generator was not damaged, but only a little dust or dirt. dust particles adhered to the one-way engine oil return valve. The steel ball and sealing belt of the valve are on the upper surface, which prevents the valve from closing tightly, which will cause the generator set to fail in operation. It sounds simple, but it took several days from when the problem occurred to when it was resolved.been resolved. Actually, I first suspected that there was something wrong with the oil return bolt, but when I pumped oil with a manual oil pump, I felt that the pressure in the oil system was basically normal, and there was also a clear oil return. noise coming from only the oil return bolt.