course 0212 7fa generator (7fh2) - tectrapro.com...3. seal oil system to ensure that the hydrogen...
TRANSCRIPT
Copyright © 2016 by Technical Training Professionals
Course 0212
7FA Generator (7FH2)
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
Copyright © 2016 by Technical Training Professionals
All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in
any form or by any means, including photocopying, recording, or other electronic or mechanical
methods, without the prior written permission of the publisher, except in the case of brief
quotations embodied in critical reviews and certain other noncommercial uses permitted by
copyright law. For permission requests, write to the publisher, addressed “Attention: Permissions
Coordinator,” at the address below.
Technical Training Professionals
9401 Indian Creek Parkway Suite 1170
Overland Park, KS 66210
www.tectrapro.com.com
Ordering Information:
Quantity sales. Special discounts are available on quantity purchases by corporations,
associations, and others. For details, contact the publisher at the address above.
Orders by U.S. trade bookstores and wholesalers. Please contact Technical Training
Professionals: Tel: (913) 338-1143; Fax: (316) 462-5649 or visit www.tectrapro.com.
Printed in the United States of America
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
7FA Generator Course
1. Generator Overview
The 7FA gas turbine generator, actual model 7FH2, is a hydrogen-cooled, 175MW machine. It
serves a dual-purpose as the starting motor via the use of the solid state LCI device.
2. Hydrogen System
The generator utilizes hydrogen gas for heat removal. The hydrogen gas system monitors
purity, maintains pressure, and provides protective actions.
3. Seal Oil System
To ensure that the hydrogen gas does not escape the generator frame, a seal oil system is
used. The seal oil system uses the turbine’s main lube oil system to maintain an oil seal around
the shaft areas that penetrate the frame.
4. Stator Design
This chapter shows the design of the interior of the generator. It explains how it is built and how
internal components are assembled.
5. Rotor Design
The rotor itself is a unique assembly of electrical components. This chapter will review the
construction and operation of the field.
6. Power Generation
This chapter discusses how the generator produces megawatts.
7. Reactive Power
This chapter covers the creation of reactive load and how it is adjusted for grid health.
8. Fault Protection
The generator utilizes devices to detect voltage and currents to provide protection. This course
covers the most common faults.
9. LCI Overview
The load commutated inverter is used to start the gas turbine using the generator as a motor.
The load commutated inverter is a solid state device and is equipped with a high-purity water
cooling system.
10. LCI Operation
This chapter reviews the operation of the LCI when utilizing the generator to start the gas
turbine.
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
212_B5_Ch1 – Overview
1. Generator
a. The turbine generator converts the mechanical energy provided by the combustion
turbine into electrical energy. This mechanical energy is in the form of rotation and
torque.
Classroom Discussion Point:
1. The 7FA gas turbine is typically paired with the “7FH2” generator and its various
configurations. To prevent confusion, we have referred to it as simply the 7FA
gas turbine generator.
2. Generators are the most efficient piece of equipment in any power block at
around 97% efficiency.
3. Although these machines are hydrogen-cooled, they are fully capable of
operating with air at a limited output.
4. See Reference 11 for the 7FH2 generator.
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
2. Bearings
a. The generator's two elliptical journal bearings, 3 and 4, reduce friction and allow for
stable high speed operation.
b. They share the combustion turbine lubrication and lift oil systems.
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
3. Hydrogen
a. To increase the efficiency and reduce the size of the generator, hydrogen is used as its
cooling medium. Due to its small molecular weight, hydrogen has excellent thermal
conductivity.
b. Along with excellent thermal conductivity, hydrogen has a wide explosive range. Due to
this danger, the generator has a seal oil system designed to prevent its leakage and
maintain its purity high.
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
4. Seals
a. At each end of the generator inside of the bearings, are the generator hydrogen seals.
Sealing is accomplished by the use of regulated seal oil which is supplied by the
turbine’s lube oil system.
5. Seal Oil
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
a. The seal oil supply to the seals is regulated by the seal oil regulator. The regulator
receives oil from the lube oil header and maintains a specific differential pressure
between the hydrogen gas pressure and the seal oil.
6. Seal Oil Drain
a. To further prevent hydrogen hazards, the generator is equipped with a vented bearing
drain enlargement tank and a loop seal on the drain pipe. This is where seal oil drains to.
b. Seal oil drains are sampled for hydrogen purity by the Hydrogen Sampling Panel.
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
7. Heat Exchangers
a. Heat created in the generator and absorbed by the hydrogen is removed via the unit’s 5
water cooled heat exchangers. Cooling water for the water coolers is provided by the
plant’s cooling water system.
b. Fans built at each end of the rotor create the differential pressure necessary to circulate
the hydrogen through the coolers and into all sections of the stator and rotor.
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
8. Collector
a. On the non-drive end of the generator is the collector and turning gear assembly. The
collector contains the brush rigging and a cooling fan attached to the rotor.
9. Turning Gear
a. Attached to the rotor is the turning gear assembly. The turning gear assembly contains
the motor, reduction gears, and synchro-self-shifting clutch.
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
Test
1) Overview
Mechanical energy converted by the generator is provided in which of the following two
forms?
A. Rotation and excitation
B. Hydrogen pressure
C. Rotation and torque
D. Cooling water flow and hydrogen pressure
2) Hydrogen Gas
Hydrogen’s excellent thermal conductivity is a result of __________.
A. Its small molecular weight
B. Pressurized environment
C. Wide explosive range
D. Low operating temperature
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
3) Conductivity Maintenance
What is hydrogen’s excellent thermal conductivity maintained by?
A. Keeping the generator cool
B. Keeping the generator pressurized
C. Monitoring of its purity
D. Using air to maintain pressure
4) Seal Oil
The main purpose of the seal oil system is to __________.
A. Minimize lube oil usage in the generator
B. Provide cooling for the hydrogen
C. Reduce the friction of generator bearings
D. Provide an oil seal to keep hydrogen in the generator
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
5) Generator Cooling
Cooling medium for use in the heat exchanger is provided from ________.
A. Fans at each of the rotor ends
B. Seal oil flow through the seals
C. Plant’s closed cooling water system
D. Differential pressure regulated by the seal oil regulator
6) Collector End
The generator brush rigging is located on the generator’s turbine end.
A. True
B. False
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
7) Components
The turning gear assembly contains which three main components?
A. Fans, rotor, and gear assembly
B. Clutch, brush rigging, and collector rings
C. Heat exchanger, reduction gears, and brush rigging
D. Motor, reduction gears, and clutch
Course GEN01A_0212_B5-7FA Generator
Copyright © 2016 by Technical Training Professionals
Test Answers
1) C
2) A
3) C
4) D
5) C
6) B
7) D