In steam turbines lubrication system plays a very important role. Lubricating oil systems generally serve the turbine and its driven object in ways other than supplying oil to the bearings. Most turbines have hydraulic control systems that use lubricating oil as the working fluid and lubricating system pressure as the actuating force. Steam turbines cannot operate without lubrication. Therefore, a turbine lubricating oil system must be designed, operated, and maintained for extreme reliability.
In steam turbines, the lubricating oil system affects overall facility loss prevention more than the mechanical system. The lubrication oil system contained combustible liquid under pressure. The lubrication oil system is designed in a way to minimize the fire hazards presented. In most cases, a good fire protection design would also include shutting of the oil supply if a fire starts. Since shutting of the oil supply could cause the mechanical destruction of the turbine unit, the design of the associated fire protection system must reflect the fact that lubricating oil system operation must continue until the turbine unit goes down.
Each steam turbine has lubricating oil systems that are independent of any other unit. A steam turbine lubricating oil system is designed to supply clean oil at the correct temperature and pressure to all bearings, control equipment, and Seals under adverse condition that results in the largest drop in the system pressure. These three conditions can be considered, failure of any single bearing and rupture of any external line or component in the control oil system. Failure of any single seal. To prevent these events from causing serious additional damage may require limited line sizes, orifice plates, or needle valves to distribute flow in service and to limit the system pressure drop produced by a component failure.
The system reservoir should be large enough to supply oil to bearings under any above conditions for at least twice the unit coastdown time from its maximum operating speed.
Steam turbine subject to damage from coastdown without lubrication requires a backup or emergency lubrication source. The backup source should be starting automatically if the normal source fails. Provide oil to the bearings in case of a crash shutdown. Operate independently of the normal facility of electrical supply.
In case of minimum duration of supply for the backup or emergency oil source may require a further extension to include the time necessary to isolate and depressive the machine after shutdown. A steam turbines unit with a forced lubrication system required the following features,
Low lubrication pressure alarm and unit shutdown.
High lubrication temperature alarm.
Oil reservoir low-level alarm.
Backup and emergency lubrication source running alarm.
High oil filters differential alarm.
Locked or plugged oil reservoir drains.
Hence Lubrication oil system installation in steam turbines are very essential to run the steam turbine smoothly. For more information please visit www.turtleturbines.com
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