Analysis of Operation of the Oil-Supply System of Steam Turbine before and after Maintenance

Abstract

Lubricants are the most important element of mating friction pairs and largely determine their reliability and service life. Components of oil systems of turbine units are susceptible to contamination of the working fluid; therefore, during equipment operation, it is necessary to take oil samples and monitor cleanliness. In many cases, when equipment is stopped for maintenance or is in standby mode, the quality of the oil is not given due attention. Ultimately, this may affect the reliability of the unit. The quality of the oil when starting a turbine is often not the same as when the unit is taken out of service. Increasing filtration efficiency plays a key role in reducing wear rates. Cleaning requirements are most important during turbine commissioning and when equipment is spinning at low speeds. To clean the working fluid during operation, effective full-flow filters are required. The research was carried out on a T-180/210 LMZ turbine unit; Tp-22S turbine oil was used as the working fluid, and the volume of the oil system was 36 m³. After modernizing the filters of the main oil tank (MOT), solid particles in the oil decreased by 5.8 times, the purity corresponds to class six to seven by GOST 17216-2001. After the turbine unit was put into operation after routine repairs, a large amount of contaminants entered the system. The amount of solid particles in the oil increased 27 times. The purity of the oil in the system increased over 14 days of operation of the turbine after routine repairs, and solid contaminants in it during this period decreased by approximately 14 times and corresponds to class eight, and that over 28 days was by approximately 25 times and corresponds to class seven according to GOST 17216-2001. This increase in oil purity is a consequence of filtering out contaminants introduced and formed in the system during routine repairs and the completion of the running-in period of the associated turbine friction pairs. The most sensitive element of the oil system is the control system. As a result of research and compilation of oil-cleanliness data, the recommended level of industrial cleanliness for the hydraulic control system is class eight (GOST 17216-2001). The most common method of reducing the risk to equipment during commissioning operation is the use of additional oil-purification equipment. Oil-purification costs can be offset by reduced maintenance costs and replacement of damaged equipment.