高压往复式压缩机活塞杆断裂等故障研究

Fracture Faults analysis on Piston Rod of a High-pressure Reciprocating Compressor

某石化公司20万t/a高压聚乙烯(LDPE/EVA)装置有一台高压五级往复式压缩机,出口压力达35 MPa,作用是将原料乙烯介质升压至二次机入口压力,是LDPE/EVA装置生产所必须满足的条件之一,公司级关键机组,装置投产12 a来,该压缩机最高压力级五段气缸的活塞杆多次发生断裂故障及活塞杆表面涂层划伤故障,同时活塞杆沉降波动大,五段气缸高压填料和尾杆填料使用周期短,严重制约装置的长周期安全生产,通过多年的现场实践和理论研究,终于找到了造成上述故障的根本原因是原始设计的五级气缸和填料润滑油注入量不足,压缩机运转时活塞杆与填料环高速往复运动摩擦,活塞杆和填料环局部过热,导致活塞杆断裂或表面涂层划伤及填料环损坏,解决措施为在压缩机外部新增一套单独的柱塞式五点注油设施,与原有注油系统并联使用,提高五级气缸注油量,通过该措施,活塞杆的断裂和表面异常划伤故障得以彻底解决,高压填料和尾杆填料寿命提高3倍以上,切实保证了装置安全长周期生产。

The 200000 t/a LDPE/EVA device of a petrochemical company is equipped with a high-pressure five-stage reciprocating compressor under an outlet pressure up to 35 MPa.The function of this compressor is to increase the pressure of the raw material ethylene medium to the pressure at the inlet of the secondary machine.This compressor is one of the preconditions for the production of the LDPE/EVA device and a company-level key unit.Since it was put into operation 12 years ago,fractures and scratches of the piston rod surface coating in the five-segment cylinder at the maximum pressure level of the compressor have occurred repeatedly.Meanwhile,the settlement fluctuations of the piston rod are great,while the service cycle of the high-pressure packing and tail rod packing in the five-stage cylinder is short,greatly restricting the long-term safe production of the device.After years of field practice and theoretical research,the root causes of the above-mentioned faults are finally identified and are as follows:the insufficient originally designed injection rate of lubricating oil for the five-stage cylinder and packing,the high-speed reciprocating friction between the piston rod and the packing ring during the operation of the compressor and the local overheating of the piston rod and the packing rod,resulting in piston rod fracture,surface coating scratch or packing ring damage.The solution is to add a separate plunger five-point oil injecting facility outside the compressor.This facility is used in parallel with the original oil injecting system to improve the injection rate of the five-stage cylinder.The faults of the piston rod,such as fracture and abnormal scratches of the surface coating of the piston rod,are thoroughly solved and the service life of the high-pressure packing and the tail rod packing is extended more than three times by adopting this solution,effectively ensuring the long-term safe production of the device.