Research On Long-term Operation Of Four Units In Catalytic Cracking Unit

As the key equipment of catalytic cracking unit, four-unit steam turbine is critical for long-term operation of catalytic cracking unit for its complex structure, various maintenance points, and difficulty in maintenance during operation. It has become an urgent issue to understand the key factors influencing the long-term operation of four-unit steam turbine and provide pertinent solutions correspondingly.The thesis mainly focuses on the study of steam turbine, flue gas turbine and unit lubrication system. With the combination of the practical experience and failure surveys upon four-unit steam turbine at home and abroad available, based on the section SEM graphic and energy spectrum analysis, the reason for failure of typical parts, the failure mechanism and the factors effecting the long-term operation of the four-unit steam turbine were researched throughly. Through analysis of typical quickly salt deposition case, it is found that the main factor influencing the long-term operation of the four-unit steam turbine is the quality of inspection and maintenance and the quality of steam entering the steam turbine. In addition, the mechanism and causes of salt deposition of steam turbine as well as the simple treatment method for salt deposition of steam turbine were presented. Besides, it is also found that the scaling of flue gas turbine, the fracture of flue gas turbine blade as well as the corrosion fracture of expansion joint of the outlet piping of the turbine were else factors influencing the long-term operation of four-unit flue gas turbine. Corresponding preventive measures are provided for specific failure reason. The quality of lubricating oil is the key factor determining the lubrication effect. During the practical operation process, the four-unit steam turbine oil station should be maintained strictly to guarantee the lubrication effect.According to the research findings, on the foundation of standard reformation of operation and maintenance, the four-unit steam turbine is working much more stably, which contributes greatly to the long-term operation of catalytic cracking unit.