Failure analysis and suggestion of #4 diesel generator set in Zhangjiakou power plant

Mainly introduces the reason of entering a diesel engine of Cummins KT38 - G motor generator diesel motor '>' > '> generator oil pan, put forward this problem solving measures.

'>' > '> diesel electric generator motor generator is in turbo generator motor' > working section after the loss of electricity to the power supply security of important equipment, mainly for turbine pump shaft, lubricating oil pump, motor generators' > hydrogen side seal oil pump, small machine anti fuel pump, lubricating oil pump, suction fan, oil station coal pulverizer oil station, air preheater auxiliary motor and other equipment, to prevent the turbine shaft bending, bearing damage and other major equipment accident has extraordinary significance. The nature of the work determines the equipment "the idea that Japan, the characteristics of one day". Therefore, it must be highly reliable.

#4 motor generator diesel motor '>' > '> generator for automobile engine factory in Chongqing imported Cummins Engine Co. Ltd. KT38 G diesel engine, power 560KWh, rated speed 1500r/min. The oil inlet nozzle stroke 7.80mm, inlet valve clearance 0.36mm, exhaust valve clearance 0.69mm 12 cylinder V type arrangement, bore 159mm, double inlet and exhaust, the total displacement of 37.8 liters. The engine uses a large cam design and a unique PT fuel system, turbocharged intake.

The unit failed to start and was suspected of being pulled by the cylinder liner and decided to overhaul it. When the oil is released before disintegration, a large amount of diesel oil is mixed in the oil, which can not play a good lubrication role at all. After removal of the cylinder cover, it is found that the exhaust ports of the three cylinders of R6, R5 and L6 have a small amount of diesel oil. Remove the cylinder head and find that there is also diesel in the cylinder.

Open the side plate of the diesel engine, remove the connecting rod tile and pull out the piston. Inspection shows that the connecting rod has serious wear and tear. Measurement of piston ring gap is 1.20MM, far higher than the standard (the standard is the first air ring: 0.50mm; second air ring: 0.40mm). Therefore, it is decided to replace the piston ring and connecting rod tile.

The analysis of the causes of diesel oil in the sump has been made:

I. PT fuel pump

The main function of the PT fuel pump is to transport the fuel with a low pressure (about 0.8~1.2MPa) to the injector. When the main shaft seal of the PT pump coupling fails, the fuel passes through the oil seal and enters the oil pan through the timing gear box. At this point, you must replace the PT pump spindle oil seal.

PT pump outlet with an electromagnetic and manual shut-off valve, when the ignition is switched on, electromagnetic shut-off valve open circuit is connected; when the ignition is switched off, the shut-off valve sealing ring in the spring under the action of closed circuit cut off. When the cut off valve seal failure or diesel engine to work after a period of time due to impurities in the diesel oil, the electromagnetic valve is not tightly closed, the fuel will be through the shut-off valve to flow to the fuel injector through the combustion chamber into the oil sump.

Two 、 injector

The function of the injector is to measure and pressurize the fuel output from the PT pump (approx. 110~120MPa) and to spray it into the combustion chamber. When the injector hole (normally about 0.2032mm) is too large or damaged, will fuel in the shutdown state drops into the combustion chamber into the oil sump. At this point, you must check and replace the abnormal fuel injector. If the fuel injector, two O ring failure, will fuel through the sealing ring into the valve chamber and the combustion chamber at any time, and then into the oil pan.

Three fuel tank

The fuel tank position higher PT fuel system, fuel in shutdown after float PT fuel tank and pump automatically flows into the fuel injector through the combustion chamber into the oil sump. And, because the higher position of the fuel tank will cause poor oil return, especially after stopping the oil return pressure is reduced, if the tank level too high, cannot return oil back to tank, can only enter the combustion chamber and the injector into the oil pan.

#4 '>' > '> diesel electric generator motor generator set and the same type of #3 diesel motor generator motor' > '>' > generator have been unable to stop the fault, thus determine the reason, PT pump outlet stop valve malfunction.

Upon examination, the injector, orifice, and O seals are all in good condition, so the cause No. two does not exist.

By measuring the oil box level remained at 1400mm height, the nozzle elevation is 1260mm, and the unit for the V type 12 cylinder arrangement, each spindle rotating 720 degrees 12 cylinder is a power, i.e. every 60 degrees with a cylinder work, so there must be shut down when the injector of a cylinder in the open position, coupled with the shutdown solenoid valve is not strict, diesel will by PT fuel pump, fuel injector into the combustion chamber, the piston ring gap, diesel oil can enter the oil pan, there are three reasons, and the main reason for the failure of the.

The maintenance of the replacement of the shutdown solenoid valve, part of the solution to the problem, but if you run for a long time, diesel impurities into the solenoid valve, and will have the same problem, so to solve fundamentally, still need to lower the fuel tank of the elevation, but due to the time, after the operation of #4 steam turbine diesel generator group must enter standby therefore, at the next stop.

The fault, in addition to the diesel engine itself reasons, start the motor and battery there are reasons, after inspection, the two start motor only one can work properly, has been replaced. The battery pack has also been replaced because it does not provide the power needed to start up. After overhaul, the unit has been debugged and entered normal standby.

Into the oil pan of diesel diesel, will reduce the oil viscosity and oil pressure and reduce all kinds of additives in the oil content of 100%; if the infiltration is more, will lead the diesel engine burning tile, cylinder and other major accidents. The piston ring, connecting rod tile wear seriously, because the oil in a large number of diesel oil, which can not form a lubricating oil film, causing serious wear and tear of moving parts. In order to avoid such accidents,