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This post was last edited by LQ198619 on 2017-5-25 at 12:40. VII. Analysis of Typical Faults and Accidents in Reciprocating Compressors 1. Abnormal exhaust temperature Abnormal exhaust temperature refers to a value that is higher than the designed level. Factors that affect the increase in exhaust temperature include intake air temperature, pressure ratio, and compression index (for air, the compression index K=1.4). Factors that affect high intake temperatures include low intercooler efficiency, or excessive scale buildup in the intercooler, which hinders heat exchange; as a result, the intake temperature in subsequent stages will inevitably be high, and so will the exhaust temperature. Air leakage from the valve and piston rings not only leads to an increase in exhaust temperature but also causes changes in the pressure between stages; whenever the pressure ratio is higher than normal, the exhaust temperature rises. Furthermore, in water-cooled machines, a lack of water or insufficient water volume will cause the exhaust temperature to rise. 2. Overheating fault: When the temperature at points of friction such as the crankshaft and bearings, the crosshead and slide plates, as well as the packing and piston rod, exceeds the specified value, it is referred to as overheating. The consequences of overheating are: first, it accelerates the wear between the friction pairs; second, the excess heat keeps accumulating until it burns the friction surfaces and causes severe damage to the machine. The main reasons for bearing overheating are: uneven fitting between the bearing and the shaft journal or an insufficient contact area ； Bearing misalignment, crankshaft bending, torsion ； Too low viscosity of the lubricating oil, blockages in the oil circuits, and faults in the oil pump that cause a lack of oil supply, etc ； During installation, leveling was not done, the gaps were not properly adjusted, the main shaft and the motor shaft were not aligned, and there was tilting between the two shafts. 3. Fracture accidents: The main locations where fracture accidents occur are as follows: Crankshaft fractures: Most of these fractures take place at the transition zone between the journal and the rounded corners of the crank arm ； Breakage of the connecting rod: Breakage of the connecting rod screw ； Cracking of cylinders and cylinder heads: Main cause – In water-cooled machines, if the cooling water inside the cylinders and cylinder heads is not drained after shutdown in winter, the water will freeze and cause the cylinders and cylinder heads to crack ； The piston rod is broken. 4. The main areas where the piston rod breaks are the thread connected to the crosshead and the thread used to secure the piston; these two points are the weak spots of the piston rod. Breakages occur frequently due to design flaws, careless manufacturing, or operational issues. If there are no issues with the design, manufacturing, or material quality, the pre-tensioning force during installation should not be too high; otherwise, when the maximum force reaches the yield limit, the piston rod will break. After long-term operation, due to excessive wear of the cylinders, the pistons in the horizontal row will sink, thereby creating additional stress at the connection threads; continued operation may lead to the breakage of the piston rod, a point that requires special attention during maintenance. Furthermore, if the piston rod is subjected to a severe impact due to damage in other areas, it is possible for the piston rod to break. 5. Combustion and explosion accidents: Oil-lubricated compressors often suffer from carbon buildup, as this not only causes the piston rings to get stuck in their grooves and disrupts the proper functioning of the valve gears, but it also reduces the area of the air flow channels and increases resistance. Under certain conditions, this carbon buildup can catch fire, leading to explosions in the compressor. Therefore, too much lubricating oil cannot be supplied into the cylinder, and gases that have not been properly filtered and contain a large amount of dust must not be drawn into the cylinder; otherwise, carbon deposits will form, and contact with gases containing large amounts of volatiles can lead to an explosion. To prevent fires and explosions, it is essential to plan regular maintenance and clean the oil deposits in the gas storage tanks and pipelines on a periodic basis.