Bearing Lube Oil and Hydraulics System Tutorial

Do you know that the turbine control and protection systems are operated through electro-hydraulic devices that are supplied with the operating oil from the Bearing Lube Oil and Hydraulics System?

At the end of this module, you will be able to:

• Identify the sub-systems that comprise the Bearing Lube Oil and Hydraulics System

• State the purpose of each of the sub-systems that comprise the Bearing Lube Oil and Hydraulics System.

• Identify the functions of the major components of each of the sub-systems that comprise the Bearing Lube Oil and Hydraulics System.

Bearing Lube Oil and Hydraulics System: Overview

The Bearing Lube Oil and Hydraulics System consists of the following sub-systems:

• Lubricating Oil System

• Combined Hydraulic and Lift Oil System

• Control and Trip Oil System

• Generator Hydrogen Seal Oil System

The major components shared by these sub-systems are:

• Piping
• Lubricating oil supply pumps
• Heat exchangers
• Filters
• Oil reservoir

In this course, each of these sub-systems will be discussed individually, including the purpose of each sub-system and the function of the major components within each sub-system.

Lubricating Oil System: Overview

The purpose of the Lubricating Oil System is to supply filtered lubricant, at the proper temperature and pressure, for operation of the turbine and associated equipment. It also absorbs the heat rejected from the generator bearings.

The Lubricating Oil System supplies lube oil to the gas turbine and generator bearings, turning gear and accessory equipment, and to the atomizing air purge compressors on dual fuel units. Additionally, the Lubricating Oil System supplies oil to the Control and Trip Oil System and the Generator Hydrogen Seal Oil System. A portion of the pressurized fluid is diverted, filtered, and again pressurized substantially for use by hydraulic control devices and as shaft lift oil.

The lube oil skid, also referred to as an accessory module, contains the oil reservoir, pumps, coolers, filters, valves, and various control and protection devices used by the Bearing Lube Oil and Hydraulics System.

Lubricating Oil System: Major Components

The major system components of the Lubricating Oil System include:

• Lube Oil Reservoir that serves as a base for the accessory module
• Two centrifugal pumps, each driven by an AC-powered electric motor
• Emergency lube oil pump driven by a DC-powered electric motor
• Dual parallel-flow lubricating oil heat exchangers
• Dual parallel-flow lubricating oil filters
• Bearing header pressure-regulating valve

• Mist eliminator with two fans
• Miscellaneous instrumentation

Lubricating Oil System: Flowpath

Under normal operating conditions, lube oil is supplied to the Lubricating Oil System from the reservoir by one of two main AC-powered motor-driven centrifugal pumps.

Lube oil is first pumped through one of the two parallel heat exchangers, each of which is designed to maintain the oil at the proper bearing-header temperature. From the in-service heat exchanger, the oil then flows through one of the two full flow parallel filters to the lube oil system loads. A three-way transfer valve controls the selection of the heat exchanger or filter set that is in use.

An air-operated pressure-regulating valve controls the oil pressure to the gas turbine and generator bearings, turning gear and accessory equipment, and to the atomizing air purge compressors on dual fuel units. The system is ventilated through a mist eliminator mounted on top of the lube oil reservoir.

Piping taps, located downstream of the filters and before the lubricating oil header pressure-regulating valve, supply oil to the Generator Hydrogen Seal Oil System, Combined Hydraulic and Lift Oil System, and Control and Trip Oil System.

Functions of Major Components: Lube Oil Reservoir

The Lube Oil Reservoir is a 6,200-gallon tank that serves as a base of the Lube Oil Accessory Module. It provides storage for the lubricant that is used by all the sub-systems of the Bearing Lube Oil and Hydraulics System.

The interior of the tank is coated with an oil-resistant protective coating. The top of the tank is the base on which the various components, such as the oil pumps and heat exchangers, are mounted.

A lubricant drain connection on the side of the accessory module is used to drain the Lube Oil Reservoir.

The Lube Oil Reservoir has two temperature switches that measure the oil tank temperature and transmit the temperature readings to the turbine control circuit.

One temperature switch measures the oil tank temperature and provides an on or off signal for the standby tank immersion heaters. The immersion heaters are designed to maintain the oil tank temperature between 70 and 80 degrees Fahrenheit when the unit is shutdown.

The other temperature switch prevents a turbine startup if the oil temperature is not above a pre-determined set-point, which indicates that the oil viscosity may not be adequate for turbine operation.

Note, that the standby tank immersion heaters are interlocked such that, when operating in AUTO, they will not activate unless a lube oil pump is in operation.

Module:	2	BLOH System Overview			Page #:		005
Chapter:	3	Lubricating Oil System			Interactivity:		MMCQ
Question Text:					Bloom’s Level:		1
Identify the major system components of the Lubricating Oil System. Select all that apply and click Submit.
1.    Nitrogen-filled bladder
2.    AC motor-driven oil pumps
3.    DC motor-driven emergency lube oil pump
4.    Heat exchangers and filters
5.    Solenoid-operated isolation valve
6.    Mist eliminator
Answers:	2, 3, 4, and 6				Remediation:	M2C3P3
Correct Feedback:			That’s correct.
Partially Correct Feedback:			That’s partially correct. Click the Remediation button for a quick review.
Incorrect Feedback:			1.	That’s incorrect. Click the Remediation button for a quick review.
			2.	The correct answers are displayed for you.
Prompt Text:			Click Forward to continue.
Notes to Developer: