Causes and troubleshooting of abnormal smoke exhau

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Causes and troubleshooting of abnormal smoke exhaust of diesel engine

diesel engine is widely used in mining machinery, engineering machinery and other industries because of its good economic and dynamic performance. During the daily use of diesel engine, the fault can be judged according to the change of smoke exhaust color, so as to achieve timely maintenance and reduce economic losses. The following is an introduction to the causes and troubleshooting of three common abnormal smoke exhaust faults of the engine. 1 causes and elimination methods of black smoke emission this phenomenon is caused by incomplete fuel combustion. When black smoke is emitted, the engine power is often reduced, the exhaust temperature is too high, and the water temperature is too high, which leads to the wear of engine parts and reduces the service life of the engine. The causes of this phenomenon (there are many causes of incomplete combustion) and the elimination methods are as follows. (1) The exhaust back pressure is too high, and nearly 10 wood plastic product manufacturers have passed the certification of China environmental label or the exhaust pipe is blocked. This situation will cause insufficient air intake, which will affect the air fuel mixture ratio and cause excessive fuel. This situation occurs: first, there are too many exhaust pipe bends (especially 90 ° bends), which should be minimized; Second, the muffler is blocked by too much soot and should be removed. (2) Insufficient air intake or blocked air intake pipe. In order to find out the cause, the following inspections should be carried out: first, whether the air filter is blocked; The second is whether the air intake pipe leaks (if this phenomenon occurs, the engine will be accompanied by a harsh air howling due to the increase of load); Third, whether the turbocharger is damaged. Check whether the exhaust wheel and booster wheel blades are damaged and whether they rotate smoothly and flexibly; Fourth, whether the intercooler is blocked. (3) The valve clearance is not adjusted correctly, and the valve sealing wire is in poor contact. Check the valve clearance, valve spring and valve seal. (4) The oil supply of each cylinder of the high-pressure oil pump is uneven or too large. Uneven oil supply will produce unstable speed and intermittent black smoke, which should be adjusted to make it balanced or within the specified range. (5) If the fuel injection is too late, the advance angle of fuel injection should be adjusted. (6) If the fuel injector works poorly or is damaged, it should be removed for cleaning and inspection. (7) The problem with fuel injector models now is that industry insiders choose the wrong ones. The imported high-speed engine has strict requirements for the selected fuel injector (injection aperture, number of holes, injection angle). If it is not selected properly, it will also cause the engine to emit black smoke. Even if the engine of the same model is used in different occasions (different output power, speed, etc.), the fuel injector models required to be used are different. If the selection is wrong, replace the fuel injector of the correct model. (8) The quality of diesel oil is poor or the brand is wrong. The imported high-speed diesel engine with direct injection combustion chamber equipped with porous fuel injector has strict requirements on the quality and brand of diesel due to its small aperture and high precision. Otherwise, the engine will emit black smoke and even make the engine unable to operate normally. Therefore, clean and qualified light diesel oil should be selected. It is recommended to use No. 0 or +10 diesel oil in summer, No. -10 or -20 diesel oil in winter, and No. -35 diesel oil in severe cold areas. (9) The cylinder liner and piston components are seriously worn. In this case, the piston ring is not tightly sealed, and the air pressure in the cylinder is seriously reduced, resulting in the diesel oil can not be fully burned and black smoke, and the engine power drops sharply. In serious cases, the engine will automatically shut down when loaded. Wear parts should be replaced. 2 causes and elimination methods of blue smoke emission blue smoke emission is caused by excessive engine oil burning in the combustion chamber. The reasons for this failure are as follows: (1) the oil pan is overfilled. Too much oil will splash to the cylinder wall with the high-speed crankshaft and rush into the combustion chamber. The troubleshooting method is to stop the machine for about 10 minutes, then check the oil dipstick and drain the excessive oil. (2) The cylinder liner and piston components are seriously worn and the clearance is too large. If the clearance is too large, a large amount of oil will rush into the combustion chamber for combustion, accompanied by the increase of engine crankcase exhaust gas. The treatment method is to replace worn parts in time. (3) The piston ring loses its function. If the piston ring is not elastic enough, it is stuck in the ring groove by carbon deposition, or the ring ports are in the same line, or the oil return hole of the oil ring is blocked, a large amount of oil will flow into the combustion chamber and burn, resulting in blue smoke emission. This paper summarizes the performance and degradation characteristics of several commonly used degradable high molecular materials at present. The method is to remove the piston ring, remove the carbon deposit, rearrange each ring port (the upper and lower ring ports are recommended to be staggered by 180 °), and replace the piston ring if necessary. (4) Excessive clearance between valve and guide. Due to wear, the gap between the two is too large. During air intake, a large amount of oil in the rocker arm chamber is sucked into the combustion chamber for combustion. The treatment method is to replace the worn valves and guides. (5) Other causes of blue smoke. If the engine oil is too thin, the engine oil pressure is too high, and the engine is not running in well, the engine oil will burn and emit blue smoke. 3 causes and elimination methods of gray and white smoke emission the gray and white exhaust gas emitted by the engine indicates that some fuel is discharged from the exhaust pipe because of low engine temperature, poor oil and gas atomization, and fuel is too late to burn. The main reasons for this phenomenon are: (1) if the fuel injection time is too late, the fuel injector drips when injecting fuel, the injection pressure is too low, and the atomization is poor. When the engine temperature is too low, it is too late to burn and is discharged in the form of white smoke. The solution is to correct the injection time and check the working condition of the fuel injector. (2) Insufficient pressure in the cylinder. Due to the wear of cylinder liner and piston ring components and poor valve sealing, the engine emits gray smoke at the beginning of starting, and then turns into light black smoke or black smoke as the engine temperature rises. The solution is to replace the worn cylinder liner and piston ring or repair the valve and valve seat ring. (3) There is water in diesel oil. If the engine emits gray smoke after starting, and the gray smoke still exists as the engine temperature rises, it is likely that there is too much water mixed in the diesel. The solution is to open the drain valve of the oil tank before starting up every day to drain the sediment and water at the bottom of the tank. To sum up, abnormal smoke exhaust is a comprehensive reflection of internal engine faults. Therefore, whether the exhaust is normal or not is one of the important signs to judge the working condition of the engine. If it can be handled in time, it can ensure the ideal use of the diesel engine and avoid unnecessary economic losses

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