FUNCTION OF EACH OIL PUMP IN TURBINE LUBRICATION SYSTEM
Heii power plant engineers today we discussed about the turbine oil system how it is working ? what are the function of turbine oil system what are the general arrangement of turbine oil system and also know about each oil pumps which is used in circulation of oil during turbine cold startup condition , normal running condition and also in emergency condition . turbine oil is very essential lubricant for the turbine bearing , generator bearing also because of its extract the heat from the bearing during turbine running condition and make the turbine smooth during operation and protect the bearing any tear and wear from the shaft movement .
Turbine oil supply system function:
1.Provide pressure oil to conditioning system and protection devices.
2.Provide lubrication oil to all bearing shafts of the unit and cooling meanwhile.
3.Provide oil to turning gearing device.
Steam turbine oil system configuration and operation instructions
This steam turbine oil system is a low pressure oil supply system mainly composed of main oil pump, is generally used to provide lubrication oil to all bearing shafts of steam turbine generator and provide pressure oil to conditioning and protection system It generally includes main oil pump, grease injector, assistant oil pump AC and DC lube oil pump, oil tank, oil-cooler, oil filter and adjustable throttle valve.
Centrifugal-type main oil pump is directly driven by steam turbine main shaft; in normal operation, exit oil pressure of oil pump is ~ 0.85MPa, this pressure oil, besides being provided to conditioning and protection system mostly is to be supplied to oil-injector.
Exit oil pressure of this oil injector is about 0.05 MPa, which supplies oil to main oil pump entrance and the rest is provided to lubrication system through the oil cooler and oil filter.Assistant oil pump shall be started before starting the unit. In steam turbine starting process, high pressure assistant electric pump provides to conditioning and protection system and provides lubrication oil to all bearing shafts through oil injector. In order to prevent pressure oil leaking through the main oil pump, main oil pump exit is equipped with a check valve. When the turbine speeds up to rated speed (the main pump exit oil pressure is higher than electric pump exit oil pressure), this oil pump is stopped using, using main oil pump instead to provide lubrication oil to conditioning and protection system of the entire unit.
When the machine is stopped, operator may start high pressure electrical oil pump first and then in the turning gearing process switch to AC lub oil pump.In order to avoid conditioning system machine stopping incident caused by the reduction of pressure oil, when the exit oil pressure of main pump is reduced to 0.85MPa, pressure switch will start high pressure AC oil pump.
When malfunction happens in the operation, the lubrication oil pressure drops, lubrication oil pressure controller will make AC lub oil pump start automatically; system is configured with a spare DC lub oil pump, when lubrication oil pressure drops, and lubrication oil pump can not work normally, lubrication oil pressure controller will maker DC lub oil pump start automatically and supply oil to lubrication system.
Notes: when unit is in normal operation, electric assistant oil pump shall stop running; while under special conditions, it is allowed to start and work.
The main oil pump is installed co-axially with the turbine rotor, which is of large flow rate, low outlet pressure and stable oil pressure. In other words, the lift-flow curvature is slow and stable in order to ensure stable oil supply to the turbine regulating system and bearing tile under variable working conditions. The main oil pump is avail of self-absorption, when under normal running, requiring 0.05－0.1 Mpa pressure oil supplied from the oil ejector to the inlet of the main oil pump.
When the rotor is static or being started up, the auxiliary oil pump is working as the substitute of the main oil pump. Start up the auxiliary oil pump prior to the the turbine start-up supplying oil to the regulating system until reached the working speed. Shut off the auxiliary oil pump and standby.When the unit is normal running, lube oil is supplied from the oil ejector to the unit; When the unit is starting up with fault at the oil ejector, put in the AC oil pump to ensure the normal supply of the lube oil.
As for the DC oil pump, when the plant power is disabled, or fault at the auxiliary oil pump, shall be put in to ensure the successful shutdown.
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