TM 5-811-6

TECHNICAL MANUAL

ELECTRIC POWER PLANT DESIGN

H E A D Q U A R T E R S , D E P A R T M E N T O F T H E A R M Y20 JANUARY 1984

TM 5-811-6

REPRODUCTION AUTHORIZATION/RESTRICTIONS

This manual has been prepared by or for the Government and, except to the extent indicated below, is publicproperty and not subject to copyright.Copyrighted material included in the manual has been used with the knowledge and permission of the proprie-tors and is acknowledged as such at point of use. Anyone wishing to make further use of any copyrighted ma-terial, by itself and apart from this text, should seek necessary permission directly from the proprietors.Reprints or republications of this manual should include a credit substantially as follows: Department of theArmy, USA, Technical Manual TM 5-811-6, Electric Power Plant Design.If the reprint or republication includes copyrighted material, the credit should also state: Anyone wishing tomake further use of copyrighted material, by itself and apart from this text, should seek necessary permissiondirectly from the proprietors.

A/(B blank)

TM 5-811-6

T ECHNICAL M A N U A L HEADQUARTERSDEPARTMENT OF THE ARMY

NO. 5-811-6 W ASHINGTON , DC 20 January 1984

ELECTRIC POWER PLANT DESIGN

CHAPTER 1. INTRODUCTIONPurpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Design philosophy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Design criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Economic considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHAPTER 2. SITE AND CIVIL FACILITIES DESIGNSelection I. Site Selection

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Environmental considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Water supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fuel supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Physical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Economic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section II. Civil Facilities, Buildings, Safety, and SecuritySoils investigation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Site development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Buildings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHAPTER 3. STEAM TURBINE POWER PLANT DESIGNSection I. Typical Plants and Cycles

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plant function and purpose. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Steam power cycle economy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cogeneration cycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Selection of cycle steam conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cycle equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Steam power plant arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section II. Steam Generators and Auxiliary SystemsSteam generator convention types and characteristics . . . . . . . . . . . . . . . . . . . . . . . .Other steam generator characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Steam generator special types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Major auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Minor auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section III. Fuel Handling and Storage SystemsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical fuel oil storage and handling system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Coal handling and storage systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section IV. Ash Handling SystemsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Description of major components.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section V. Turbines and Auxiliary SystemsTurbine prime movers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Generators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Turbine features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Governing and control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Turning gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Lubrication systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Extraction features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Instruments and special tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section VI. Condenser and Circulating Water SystemIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Description of major components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Environmental concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section VII. Feedwater SystemFeedwater heaters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Boiler feed pumps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Feedwater supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section VIII. Service Water and Closed Cooling SystemsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Description of major components.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Paragraph

1-11-21-31-4

2-12-22-32-42-52-6

2-72-82-9

3-13-23-33-43-53-63-7

3-83-93-103-113-12

3-133-143-15

3-163-17

3-183-193-203-213-223-233-243-25

3-263-273-28

3-293-303-31

3-323-33

Page

1-11-11-11-5

2-12-12-12-12-12-1

2-22-22-2

3-13-13-13-33-63-63-6

3-93-113-123-123-25

3-263-263-27

3-293-30

3-303-323-323-333-333-333-343-34

3-343-353-40

3-403-413-43

3-433-44

i

TM 5-811-6

CHAPTER 3. STEAM TURBINE POWER PLANT DESIGN (Continued)Description of systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Reliability of systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section IX. Water Conditioning SystemsWater conditioning selection.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section X. Compressed Air SystemsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Description of major components.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Description of systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHAPTER 4. GENERATOR AND ELECTRICAL FACILITIES DESIGNSection I. Typical Voltage Ratings and Systems

Voltages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Station service power syetems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section II. GeneratorsGeneral types and standards.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Features and acceesories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Excitation systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section III. Generator Leads and SwitchyardGeneral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Generator leads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Switchyard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section IV. TransformersGenerator stepup transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Auxiliary transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Unit substation transformer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section V. Protective Relays and MeteringGenerator, stepup transformer and switchyard relaying . . . . . . . . . . . . . . . . . . . . . . .Switchgear and MCC protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Instrumentation and metering. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section VI. Station Service Power SystemsGeneral requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Auxiliary power transformers. . . . . . . . . . . . . . . . . . . . . . . . .... . . . . . . . . . . . . . . . .4160 volt switchgear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .480 volt unit substations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .480 volt motor control centers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Conduit and tray systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Distribution outside the power plant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section VII. Emergency Power SystemBattery and charger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Emergency ac system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section VIII. MotorsGeneral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Horsepower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Conduit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Motor details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section IX. Communication SystemsIntraplant communications.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Telephone communications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CHAPTER 5. GENERAL POWER PLANT FACILITIES DESIGNSection I. Instruments and Control Systems

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Control panels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Automatic control systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Monitoring instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Alarm and annunciator systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section II. Heating, Ventilating and Air Conditioning SystemsIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Operations areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Service areas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Paragraph

3-343-353-363-37

3-38

3-393-403-41

4-14-2

4-34-44-5

4-64-74-8

4-94-104-11

4-124-134-14

4-154-164-174-184-194-204-214-224-23

4-244-25

4-264-274-284-294-304-314-32

4-334-34

Page

3-44 3-453-453-45

3-45

3-463-463-50

-14-1

4-34-74-8

4-84-94-13

4-164-164-17

4-184-194-19

4-204-204-204-214-214-214-214-214-22

4-234-23

4-234-244-244-244-244-244-24

4-244-26

5-15-25-35-45-5

5-65-75-8

5-15-15-55-95-14

5-145-145-14

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TM 5-811-6

Paragraph Page

5-155-155-15

5-175-175-175-215-215-215-215-21

5-22

5-225-235-24

6-16-16-26-26-26-3

7-17-1

7-27-27-27-27-2

7-37-37-3

8-18-1

8-18-2

Page1-41-53-23-33-53-73-83-93-133-153-16

CHAPTER 5. GENERAL POWER PLANT FACILITIES DESIGN (Continued)Section 111. Power and Service Piping Systems

5-95-105-11

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Piping design fundamentals... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Specific system design considerations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section IV. Thermal Insulation and Freeze ProtectionIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-12

5-135-145-155-165-175-185-19

Insulation design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Insulation materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Control of useful heat losses.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Safety insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cold surface insulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Economic thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Freeze protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section V. Corrosion Protection5-20General remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section VI. Fire ProtectionIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Design considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

.

CHAPTER 6.

5-215-225-23Support facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GASTURBINE POWER PLANT DESIGNGeneral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Turbine-generator selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-16-26-36-46-56-6

Fuels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plant arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Waste heat recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Equipment and auxiliary systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

DIESEL ENGINE POWER PLANT DESIGNSection I. Diesel Engine Generators

Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fuel selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section II. Balance of Plant Systems

CHAPTER 7.

L

7-17-2

7-37-47-57-67-7

General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cooling systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Combustion air intake and exhaust systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fuel storage and handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Engine room ventilation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section III. Foundations and BuildingGeneral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Engine foundation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7-87-97-10Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

COMBINED CYCLE POWER PLANTSSection I. Typical Plants and Cycles

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plant details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Section II. General Design ParametersBackground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Design approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

REFERENCES

.

CHAPTRR 8.

8-18-2

.

8-38-4

APPENDIX A:BIBLIOGRAPHY

LIST OF FiGURES

Figure No.

Figure 1-11-23-13-23-33-43-53-63-73-83-9

Typical Metropolitan Area Load Curves. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Annual Load Duration Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Straight Condensing Cycle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Turbine Efficiencies Vs.Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical CondensingControlled Extraction Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Smal1 2-Unit Power Plant "A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Smal1 2-Unit Power Plant B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Critical Turbine Room Bay and Power Plant "BDimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fluidized Bed Combustion Boiler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Theorectical Air and Combustion Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Minimum Metal Temperatures for Boiler Heat Recovery Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

TM 5-811-6

Page

3-103-113-123-133-143-154-14-24-3

4-44-54-64-74-85-16-17-18-1

Table No.

Table 1-11-21-31-43-13-23-33-43-53-63-73-83-93-103-113-123-133-143-154-14-25-15-25-35-45-55-65-7

Coal Handling System Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Coal Handling System for Spreader Stoker Fired Boiler (with bucket elevator). . . . . . . . . . . . . . . . . . .Pneumatic Ash Handling Systems-Variations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Types of Circulating Water Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Compressed Air System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Arrangement of Air Compressor and Acceesories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Station ConnectionsTwo Unit Station Common Bus Arrangement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Station ConnectionsTwo Unit StationUnit ArrangmentGenerator at Distribution Voltage. . . . . . . . . .Station ConnectionsTwo Unit StationUnit ArrangementDistribution Voltage Higher Than Genera-tion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .One Lone Diagram-TypicalStation Service Power System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Synchronizing Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Main and TransferBus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Ring Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Breaker and a Half Bus.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Economical Thickness of Heat Insulation (Typical Curves) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Indoor Simple Cycle Gas Turbine Generator PowerPlant.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Typical Diesel Generator Power Plant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Combined Cycle Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

LIST OF TABLES

General Description of Type of Plant.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Diesel Class and Operational Characteristics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Plant Sizes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Deeign Criteria Requirements.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Theoretical Steam Rates for Typical Steam Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Fuel Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Indivdual Burner Turndown Ratios . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Emission Levels Allowable, National Ambient Air Quality Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Uncontrolled Emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Characteristics of Cyclones for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Characteristics of Scrubbers for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Characterietics of Electrostatic Precipitators (ESP) for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . . .Characteristics of Baghouses for Particulate Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Characteristics of Flue-Gas Desulfurization Systems for Particulate Control. . . . . . . . . . . . . . . . . . . . . . . . . . .Techniques for Nitrogen Oxide Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Condenser Tube Design Velocities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .General Guide for Raw Water Treatment of Boiler Makeup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Internal Chemical Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Effectiveness of Water Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Standard Motor Control Center Enclosures. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Suggested Locations for Intraplant Communication System Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .List of Typical Instrumente and Devices for Boiler-Turbine Mechanical Panel. . . . . . . . . . . . . . . . . . . . . . . . . .List of Typical Instrument and Devices for Common Services Mechanical Panel. . . . . . . . . . . . . . . . . . . . . . .List of Typical Instruments and Devices for Electrical (Generator and Switchgear) Panel . . . . . . . . . . . . . . . .List of Typical Instrument and Devices for Diesel Mechanical Panel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Sensing Elements for Controls and Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Piping Codes and Standards for Power Plants . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Characteristics of Thermal Insulations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3-263-28 3-313-383-503-514-24-4

4-54-64-94-104-114-125-226-37-48-3

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1-21-31-31-33-43-103-143-173-183-19 3-203-213-223-233-243-363-473-483-494-224-255-15-45-65-85-105-165-18

iv

TM 5-811-6

CHAPTER 1

INTRODUCTION

1-1. Purposea. General: This manual provides engineering

data and criteria for designing electric power plantswhere the size and characteristics of the electricpower load and the economics of the particular facil-it y justify on-site generation. Maximum size ofplant considered in this manual is 30,000 kW.

b. References: A list of references used in thismanual is contained in Appendix A. Additionally, aBibliography is included identifying sources of ma-terial related to this document.

1-2. Design philosophya. General. Electric power plants fall into several

categories and classes depending on the type ofprime mover. Table 1-1 provides a general descrip-tion of plant type and related capacity require-ments. For purposes of this introduction Table 1-2defines, in more detail, the diesel plant classes andoperational characteristics; additional informationis provided in Chapter 7. No similar categories havebeen developed for gas turbines. Finally, for pur-poses of this manual and to provide a quick scale forthe plants under review here, several categorieshave been developed. These are shown in Table 1-3.

b. Reliability. Plant reliability standards will beequivalent to a l-day generation forced outage in 10years with equipment quality and redundancy se-lected during plant design to conform to this stand-ard.

c. Maintenance. Power plant arrangement willpermit reasonable access for operation and mainte-nance of equipment. Careful attention will be givento the arrangement of equipment, valves, mechan-ical specialties, and electrical devices so that rotors,tube bundles, inner valves, top works, strainers,contractors, relays, and like items can be maintainedor replaced. Adequate platforms, stairs, handrails,and kickplates will be provided so that operatorsand maintenance personnel can function conven-iently and safely.

d. Future expansion. The specific site selected forthe power plant and the physical arrangement of theplant equipment, building, and support facilitiessuch as coal and ash handling systems, coal storage,circulating water system, trackage, and accessroads will be arranged insofar as practicable to allowfor future expansion.

1-3. Design criteriaa. General requirements. The design will provide

for a power plant which has the capacity to providethe quantity and type of electric power, steam andcompressed air required. Many of the requirementsdiscussed here are not applicable to each of the plantcategories of Table 1-1. A general overview is pro-vided in Table 1-4.

b. Electric power loads. The following informa-tion, as applicable, is required for design:

(1) Forecast of annual diversified peak load tobe served by the project.

(2) Typical seasonal and daily load curves andload duration curves of the load to be served. Ex-ample curves are shown in Figures 1-1 and 1-2.

(3) If the plant is to operate interconnected withthe local utility company, the designer will need in-formation such as capacity, rates, metering, and in-terface switchgear requirements.

(4) If the plant is to operate in parallel withexisting generation on the base, the designer willalso need:

(a) An inventory of major existing generationequipment giving principal characteristics such ascapacities, voltages, steam characteristics, backpressures, and like parameters.

(b) Incremental heat rates of existing boiler-turbine units, diesel generators, and combustionturbine generator units.

(c) Historical operating data for each existinggenerating unit giving energy generated, fuel con-sumption, steam exported, and other related infor-mation.

(5) Existing or recommended distribution vol-tage, generator voltage, and interconnecting substa-tion voltages.

(6) If any of the above data as required for per-forming the detailed design is unavailable, the de-signer will develop this data.

c. Exports team loads.(1) General requirements. If the plant will ex-

port steam, information similar to that required forelectric power, as outlined in subparagraph c above,will be needed by the designer.

(2) Coordination of steam and electric powerloads. To the greatest extent possible, peak, season-al, and daily loads for steam will be coordinated withthe electric power loads according to time of use.

1-1

Category

Primary

Standby

Table 1-1. General Description of Type of Plant.

TYPE OF POWERCapacity No Export Steam

Adequate to meetrequirement .

Adequate withmobilization

all peacetime Purchased electric power to matchelectr ic load.

Continuous duty diesel plant,Class A diesel.

Straight condensing boilers andand turbines matched in capacityas units; enough units so plantwithout largest unit can carryemergency load.

prime source to match Purchased electric power.needs; or alone to supply

emergency electric load and exportsteam load in case of primary source Standby diesel plant, Class Bout age. diesel .

Equal to primary source . . . . . . . . . . . . Retired straight condensing plant.

Emergency To supply that part of emergency load Fixed emergency diesel plant,that cannot be interrupted for m o r e Class C diesel.than 4 hours. Mobile utilities support equipment.

With Export Steam

Purchased electric power and steam tomatch electric load plus supplementaryboiler plant to match export steam load.

Automatic back pressure steam plant plusautomatic packaged firetube boiler tosupplement requirements of export steamload.

Automatic extraction steam plant boilersand turbines matched in capacity se unitsand enough units installed so that plantwithout largest unit can carry emergencyload.

Purchased electric power and steam tomatch electric power load plus supple-mentary boiler plant.

Standby diesel plant with supplementaryboiler plant.

Retired automatic extraction steam plant.

None.

None.

NAVFAC DM3

TM 5-811-6

Table 1-2. Diesel Class and Operational Characteristics.

Fu1l Load RatingCapabil i ty Expected Operating Hours

Minimum OperatingClass Usage Hours Period -

" "A . . . . . . . . . Continuous . . . . . . . 8,000 . . . . . Yearly . . . . . . . 4,000 hours plus . . . . .

B . . . . . . . . . Standby . . . . . . . . . . 8,000 . . . . . Yearly . . . . . . . 1,000 to 4,000 hours .

c . . . . . . . . . Emergency . . . . . . . . 650 . . . . . Monthly* . . . . . Under 1,000 hours . . . .

*Based on a 30-day month.

U . S . A r m y C o r p s o f E n g i n e e r s

C a t e g o r y

S m a l l

M e d i u m

L a r g e

Table-3. Plant Sizes.

S i z e

o to 2 , 5 0 0 k W

2 , 5 0 0 k W t o 1 0 , 0 0 0 k W

1 0 , 0 0 0 k W t o 3 0 , 0 0 0 k W

U . S . A r m y C o r p s o f E n g i n e e r s

Table-4. Design Criteria Requirements.

C l a s s( P l a n t C a t e g o r y )

A ( P r i m a r y )

B ( S t a n d b y )

C ( E m e r g e n c y )

E l e c t r i cP o w e rL o a d s

A

A

c r i t i c a ll o a d s o n l y

A = A p p l i c a b l eN / A = N o t A p p l i c a b l e

First Ten Years

40,000 hours plus

20,000 to 40,000 hours

Under 10,000 hours

E x p o r tSt earnL o a d s

A

N / A

N / A

F u e lS o u r c e

a n d W a t e r S t a c k W a s t eC o s t Supp ly E m i s s i o n D i s p o s a l

A A A A

A N / A N / A A

A N / A N / A N /A

C o u r t e s y o f P o p e , E v a n s a n d R o b b i n s ( N o n - C o p y r i g h t e d )

1-3

TM 5-811-6

This type of information is particularly important ifthe project involves cogeneration with the simul-taneous production of electric power and steam.

d. Fuel source, and cost. The type, availability,and cost of fuel will be determined in the earlystages of design; taking into account regulatory re-quirements that may affect fuel and fuel characteris-tics of the plant.

e. Water supply. Fresh water is required forthermal cycle makeup and for cooling tower or cool-ing pond makeup where once through water for heatrejection is unavailable or not usable because ofregulatory constraints. Quantity of makeup willvary with the type of thermal cycle, amount of con-densate return for any export steam, and the maxi-mum heat rejection from the cycle. This heat rejec-tion load usually will comprise the largest part ofthe makeup and will have the least stringent re-quirements for quality.

f. Stack emissions. A steam electric power plant

----- Sumner LoadWinter Load

Kw

1

will be designed for the type of stack gas cleanupequipment which meets federal, state, and munici-pal emission requirements. For a solid fuel fired boil- er, this will involve an electrostatic precipitator orbag house for particulate, and a scrubber for sulfurcompounds unless fluidized bed combustion or com-pliance coal is employed. If design is based on com-pliance coal, the design will include space and otherrequired provision for the installation of scrubberequipment. Boiler design will be specified as re-quired for NOx control.

g. Waste disposal.(1) Internal combustion plants. Solid and liq-

uid wastes from a diesel or combustion turbine gen-erating station will be disposed of as follows: Mis-cellaneous oily wastes from storage tank areas andsumps will be directed to an API separator. Supple-mentary treating can be utilized if necessary to meetthe applicable requirements for waste water dis-charge. For plants of size less than 1,000 kW, liquid

.URBAN[NDUSTRIAL TRACTION

LOAD LOAD

1 2 6 1 2 6 1 2 6 1 2 6 1 2 6 1 2 6 1 2AM PM AM PM AM PM

FROM POWER STATION ENGINEERING AND ECONOMY BY SROTZKI AND LOPAT.COPYRIGHT BY THE MC GRAW-HILL BOOK COMPANY, INC. USED WITH THEPERMISSION OF MC GRAW-HILL BOOK COMPANY.

Figure 1-1. Typical metropolitan area load curves.

1-4

TM 5-811-6

oily wastes will be accumulated in sumps or smalltanks for removal. Residues from filters and centri-fuges will be similarly handled.

(2) Steam electric stations. For steam electricgenerating stations utilizing solid fuel, both solidand liquid wastes will be handled and disposed of inan environmentally acceptable manner. The wastescan be categorized generally as follows:

(a) Solid wastes. These include both bottomash and fly ash from boilers.

(b) Liquid wastes. These include boiler blow-down, cooling tower blowdown, acid and causticwater treating wastes, coal pile runoff, and variouscontaminated wastes from chemical storage areas,sanitary sewage and yard areas.

h. Other environmental considerations. Other en-vironmental considerations include noise controland aesthetic treatment of the project. The final lo-cation of the project within the site area will be re-viewed in relation to its proximity to hospital andoffice areas and the civilian neighborhood, if appli-cable. Also, the general architectural design will bereviewed in terms of coordination and blending with

I

the style of surrounding buildings. Any anticipatednoise or aesthetics problem will be resolved prior tothe time that final site selection is approved.

1-4. Economic considerationsa. The selection of one particular type of design

for a given application, when two or more types ofdesign are known to be feasible, will be based on theresults of an economic study in accordance with therequirements of DOD 4270.1-M and the NationalEnergy Conservation Policy Act (Public Law95-619,9 NOV 1978).

b. Standards for economic studies are containedin AR 11-28 and AFR 178-1, respectively. Addi-tional standards for design applications dealingwith energy/fuel consuming elements of a facilityare contained in the US Code of Federal Regula-tions, 20 CFR 436A. Clarification of the basic stand-ards and guidelines for a particular application andsupplementary standards which may be required forspecial cases may be obtained through normal chan-nels from HQDA (DAEN-ECE-D), WASH DC20314.

I0 1000 2000 3000 4000 5000 6000 7000 8000 8760-

U.S. Army Corps of

Figure 1-2.

HOURS

Engineers

Typical annual load duration curve.

1-5

-

TM 5-811-6

CHAPTER 2

SITE AND CIVIL FACILITIES DESIGN

Section 1. SITE SELECTION

2-1. IntroductionSince the selection of a plant site has a significantinfluence on the design, construction and operatingcosts of a power plant, each potential plant site willbe evaluated to determine which is the mosteconomically feasible for the type of power plant be-ing considered.

2-2. Environmental considerationsa. Rules and regulations. All power plant design,

regardless of the type of power plant, must be in ac-cordance with the rules and regulations which havebeen established by Federal, state and local govern-mental bodies.

b. Extraordinary design features. To meet var-ious environmental regulations, it is often necessaryto utilize design features that will greatly increasethe cost of the power plant without increasing its ef-ficiency. For example, the cost of the pollution con-trol equipment that will be required for each site un-der consideration is one such item which must becarefully evaluated.

2-3. Water supplya. General requirements. Water supply will be

adequate to meet present and future plant require-ments. The supply maybe available from a local mu-nicipal or privately owned system, or it may be nec-essary to utilize surface or subsurface sources.

b. Quality. Water quality and type of treatmentrequired will be compatible with the type of powerplant to be built.

c. Water rights. If water rights are required, it willbe necessary to insure that an agreement for waterrights provides sufficient quantity for present andfuture use.

d. Water wells. If the makeup to the closed sys-tem is from water wells, a study to determine watertable information and well drawdown will be re-quired. If this information is not available, test wellstudies must be made.

e. Once-through system. If the plant has a oncethrough cooling system, the following will be deter-mined:

(1) The limitations established by the appro-priate regulatory bodies which must be met to ob-

tain a permit required to discharge heated water tothe source.

(2) Maximum allowable temperature rise per-missible as compared to system design parameters.If system design temperature rise exceeds permissi-ble rise, a supplemental cooling system (coolingtower or spray pond) must be incorporated into thedesign.

(3) Maximum allowable temperature for riveror lake after mixing of cooling system effluent withsource. If mixed temperature is higher than allow-able temperature, a supplemental cooling systemmust be added. It is possible to meet the conditionsof (2) above and not meet the conditions in this sub-paragraph.

(4) If extensive or repetitive dredging of wat-erway will be necessary for plant operations.

(5) The historical maximum and minimumwater level and flow readings. Check to see that ade-quate water supply is available at minimum flowand if site will flood at high level.

2-4. Fuel supplySite selection will take into consideration fuel stor-age and the ingress and egress of fuel delivery equip-ment.

2-5. Physical characteristicsSelection of the site will be based on the availabilityof usable land for the plant, including yard struc-tures, fuel handling facilities, and any future expan-sion. Other considerations that will be taken into ac-count in site selection are:

-Soil information.-Site drainage.- Wind data.-Seismic zone.-Ingress and egress.

For economic purposes and operational efficiency,the plant site will be located as close to the load cen-ter as environmental conditions permit.

2-6. EconomicsWhere the choice of several sites exists, the final se-lection will be based on economics and engineeringstudies.

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.TM 5-811-6

Section Il. CIVIL FACILITIES, BUILDINGS, SAFETY, AND SECURITY

2-7. Soils investigationAn analysis of existing soils conditions will be madeto determine the proper type of foundation. Soilsdata will include elevation of each boring, watertable level, description of soil strata including thegroup symbol based on the Unified Soil Classifica-tion System, and penetration data (blow count). Thesoils report will include recommendations as to typeof foundations for various purposes; excavation, de-watering and fill procedures; and suitability of on-site material for fill and earthen dikes including dataon soft and organic materials, rock and other perti-nent information as applicable.

2-8. Site developmenta. Grading and drainage.

(1) Basic criteria. Determination of final grad-ing and drainage scheme for a new power plant willbe based on a number of considerations includingsize of property in relationship to the size of plantfacilities, desirable location on site, and plant accessbased on topography. If the power plant is part ofan overall complex, the grading and drainage will becompatible and integrated with the rest of the com-plex. To minimize cut and fill, plant facilities will belocated on high ground and storm water drainagewill be directed away from the plant. Assuming onsite soils are suitable, grading should be based onbalanced cut and fill volume to avoid hauling of ex-cess fill material to offsite disposal and replacementwith expensive new material.

(2) Drainage. Storm water drainage will beevaluated based on rainfall intensities, runoff char-acteristics of soil, facilities for receiving stormwater discharge, and local regulations. Storm waterdrains or systems will not be integrated with sani-tary drains and other contaminated water drainagesystems.

(3) Erosion prevention. All graded areas will bestabilized to control erosion by designing shallowslopes to the greatest extent possible and by meansof soil stabilization such as seeding, sod, stone, rip-rap and retaining walls.

b. Roadways.(1) Basic roadway requirements. Layout of

plant roadways will be based on volume and type oftraffic, speed, and traffic patterns. Type of traffic orvehicle functions for power plants can be catego-rized as follows:

-Passenger cars for plant personnel.-Passenger cars for visitors.-Trucks for maintenance material deliveries.-Trucks for fuel supply.

-Trucks for removal of ash, sludge and otherwaste materials.

(2) Roadway material and width. Aside fromtemporary construction roads, the last two catego-ries described above will govern most roadway de-sign, particularly if the plant is coal fired. Roadwaymaterial and thickness will be based on economicevaluations of feasible alternatives. Vehicular park-ing for plant personnel and visitors will be located inareas that will not interfere with the safe operationof the plant. Turning radii will be adequate to han-dle all vehicle categories. Refer to TM 5-803-5/ NAVPAC P-960/AFM 88-43; TM 5-818-2/AFM 88-6, Chap. 4; TM 5-822-2/AFM 88-7, Chap. 7; TM 5-822-4/AFM 88-7, Chap. 4; TM5-822 -5/AFM 88-7, Chap. 3; TM 5-822-6/AFM88-7, Chap. 1; TM 5-822-7/AFM 88-6, Chap. 8; andTM 5-822-8.

c. Railroads. If a railroad spur is selected to han-dle fuel supplies and material and equipment deliv-eries during construction or plant expansion, the de-sign will be in accordance with American RailwayEngineering Association standards. If coal is thefuel, spur layout will accommodate coal handling fa-cilities including a storage track for empty cars. Ifliquid fuel is to be handled, unloading pumps andsteam connections for tank car heaters may be re-quired in frigid climates.

2-9. Buildingsa. Size and arrangement.

(1) Steam plant. Main building size and ar-rangement depend on the selected plant equipmentand facilities including whether steam generatorsare indoor or outdoor type; coal bunker or silo ar-rangement; source of cooling water supply relativeto the plant; the relationship of the switchyard tothe plant; provisions for future expansion; and , aesthetic and environmental considerations. Gener-ally, the main building will consist of a turbine baywith traveling crane; an auxiliary bay for feedwaterheaters, pumps, and switchgear; a steam generatorbay (or firing aisle for semi-outdoor units); and gen-eral spaces as may be required for machine shop,locker room, laboratory and office facilities. Thegeneral spaces will be located in an area that will notinterfere with future plant expansion and isolatedfrom main plant facilities to control noise. For verymild climates the turbine generator sets and steamgenerators may be outdoor type (in a weather pro-tected, walk-in enclosure) although this arrange-ment presents special maintenance problems. If in-corporated, the elevator will have access to the high-

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TM 5-811-6

est operating level of the steam generator (drum lev-els).

(2) Diesel plant. The requirements for a build-ing housing a diesel generator plant are the same asfor a steam turbine plant except that a steam gener-ator bay is not required.

b. Architectural treatment.(1) The architectural treatment will be de-

veloped to harmonize with the site conditions, bothnatural and manmade. Depending on location, theenvironmental compatibility y may be the determin-ing factor. In other cases the climate or user prefer-ence, tempered with aesthetic and economic factors,will dictate architectural treatment. Climate is acontrolling factor in whether or not a total or partialclosure is selected. Semi-outdoor construction withthe bulk of the steam generator not enclosed in aboiler room is an acceptable design.

(2) For special circumstances, such as areaswhere extended periods of very high humidity, fre-quently combined with desert conditions giving riseto heavy dust and sand blasting action, indoor con-struction with pressurized ventilation will be re-quired not only for the main building but also, gen-erally, for the switchyard. Gas enclosed switchyardinstallations may be considered for such circum-stances in lieu of that required above.

(3) Control rooms, offices, locker rooms, and some out-buildings will be enclosed regardless of en-

closure selected for main building. Circulating waterpumps may be installed in the open, except in themost severe climates. For semi-outdoor or outdoorstations, enclosures for switchgear and motor con-trols for the auxiliary power system will be enclosedin manufacturer supplied walk-in metal housings orsite fabricated closures.

c. Structural design.(1) Building framing and turbine pedestals.

Thermal stations will be designed utilizing conven-tional structural steel for the main power stationbuilding and support of boiler. The pedestal for sup-porting the turbine generator (and turbine drivenboiler feed pump if utilized) will be of reinforced con-crete. Reinforced concrete on masonry constructionmay be used for the building framing (not for boilerframing); special concrete inserts or other provisionmust be made in such event for support of piping,trays and conduits. An economic evaluation will bemade of these alternatives.

(2) Exterior walls. The exterior walls of mostthermal power stations are constructed of insulatedmetal panels. However, concrete blocks, bricks, orother material may be used depending on the aes-thetics and economics of the design.

(3) Interior walls. Concrete masonry blocks willbe used for interior walls; however, some specialized

areas, such as for the control room enclosure and foroffices, may utilize factory fabricated metal walls,fixed or moveable according to the application.

(4) Roof decks. Main building roof decks will beconstructed of reinforced concrete or ribbed metaldeck with built-up multi-ply roofing to provide wat-erproofing. Roofs will be sloped a minimum of 1/4,-inch per foot for drainage.

(5) Floors. Except where grating or checkeredplate is required for access or ventilation, all floorswill be designed for reinforced concrete with a non-slip finish.

(6) Live loads. Buildings, structures and allportions thereof will be designed and constructed tosupport all live and dead loads without exceedingthe allowable stresses of the selected materials inthe structural members and connections. Typicallive loads for power plant floors are as follows:

(a) Turbine generator floor 500 psf(b) Basement and operating floors except

turbine generator floor 200 psf(c) Mezzanine, deaerator, and

miscellaneous operating floors 200 psf(d) Offices, laboratories, instrument

shops, and other lightly loaded areas 100 psfLive loads for actual design will be carefully re-viewed for any special conditions and actual loadsapplicable.

(7) Other loads. In addition to the live and deadloads, the following loadings will be provided for:

(a) Wind loading. Building will be designed toresist the horizontal wind pressure available for thesite on all surfaces exposed to the wind.

(b) Seismic loading. Buildings and otherstructures will be designed to resist seismic loadingin accordance with the zone in which the building islocated.

(c) Equipment loading. Equipment loads arefurnished by the various manufacturers of eachequipment item. In addition to equipment deadloads, impact loads, short circuit forces for genera-tors, and other pertinent special loads prescribed bythe equipment function or requirements will be in-cluded.

d. Foundation design.(1) Foundations will be designed to safely sup-

port all structures, considering type of foundationand allowable bearing pressures. The two most com-mon types of foundations are spread footings andpile type foundations, although raft type of otherspecial approaches may be utilized for unusual cir-cumstances.

(2) Pile type foundations require reinforcedconcrete pile caps and a system of reinforced con-crete beams to tie the caps together. Pile load capa-bilities may be developed either in friction or point

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TM 5-811-6

bearing. The allowable load on piles will be deter-mined by an approved formula or by a load test.Piles can be timber, concrete, rolled structural steelshape, steel pipe, or steel pipe concrete filled.

(3) Design of the reinforced concrete turbinegenerator or diesel set foundation, both mat andpedestal, will be such that the foundation is isolatedfrom the main building foundations and structuresby expansion joint material placed around its perim-eter. The design will also insure that the resonanceof the foundation at operating speed is avoided inorder to prevent cracking of the foundation anddamage to machines caused by resonant vibration.The foundation will be designed on the basis of de-flection. The limits of deflection will be selected toavoid values of natural frequency by at least 30 per-cent above or 30 percent below operating speed.

(4) Vibration mounts or floating floor foun-dations where equipment or equipment foundationinertia blocks are separated from the main buildingfloor by springs or precompressed material will gen-erally not be used in power plants except for ventila-tion fans and other building service equipment. Inthese circumstances where such inertia blocks areconsidered necessary for equipment not normally somounted, written justification will be included inthe project design analysis supporting such a neces-sity.

(5) The location of turbine generators, diesel en-gine sets, boiler feed pumps, draft fans, compres-sors, and other high speed rotating equipment onelevated floors will be avoided because of the diffi-culty or impossibility of isolating equipment foun-dations from the building structure.

2-10. Safety.a. Introduction. The safety features described in

the following paragraphs will be incorporated intothe power plant design to assist in maintaining ahigh level of personnel safety.

b. Design safety features. In designing a powerplant, the following general recommendations onsafety will be given attention:

(1) Equipment will be arranged with adequateaccess space for operation and for maintenance.Wherever possible, auxiliary equipment will be ar-ranged for maintenance handling by the main tur-bine room crane. Where this is not feasible, mono-rails, wheeled trucks, or portable A-frames shouldbe provided if disassembly of heavy pieces is re-quired for maintenance.

(2) Safety guards will be provided on movingparts of all equipment.

(3) All valves, specialties, and devices needingmanipulation by operators will be accessible with-out ladders, and preferably without using chain

wheels. This can be achieved by careful piping de-sign, but some access platforms or remote mechani-cal operators may be necessary.

(4) Impact type handwheels will be used forhigh pressure valves and all large valves.

(5) Valve centers will be mounted approximate-ly 7 feet above floors and platforms so that risingstems and bottom rims of handwheels will not be ahazard.

(6) Stairs with conventional riser-tread propor-tions will be used. Vertical ladders, installed only asa last resort, must have a safety cage if required by .the Occupational Safety and Health Act (OSHA).

(7) All floors, gratings and checkered plates willhave non-slip surfaces.

(8) No platform or walkway will be less than 3 feet wide.

(9) Toe plates, fitted closely to the edge of allfloor openings, platforms and stairways, will be pro-vided in all cases.

(10) Adequate piping and equipment drains towaste will be provided.

(11) All floors subject to washdown or leaks willbe sloped to floor drains.

(12) All areas subject to lube oil or chemicalspills will be provided with curbs and drains,

(13) If plant is of semi-outdoor or outdoor con-struction in a climate subject to freezing weather,weather protection will be provided for critical operating and maintenance areas such as the firingaisle, boiler steam drum ends and soot blower loca-tions.

(14) Adequate illumination will be providedthroughout the plant. Illumination will comply withrequirements of the Illuminating Engineers Society(IES) Lighting Handbook, as implemented by DOD 4270.1-M.

(15) Comfort air conditioning will be providedthroughout control rooms, laboratories, offices andsimilar spaces where operating and maintenancepersonnel spend considerable time.

(16) Mechanical supply and exhaust ventilationwill be provided for all of the power plant equipmentareas to alleviate operator fatigue and prevent accu-mulation of fumes and dust. Supply will be ductedto direct air to the lowest level of the power plantand to areas with large heat release such as the tur-bine or engine room and the boiler feed pump area.Evaporative cooling will be considered in low hu-midity areas. Ventilation air will be filtered andheated in the winter also, system air flow capacityshould be capable of being reduced in the winter.Battery room will have separate exhaust fans to re-move hydrogen emitted by batteries as covered inTM 5-811-2/AFM 88-9, Chap. 2.

(17) Noise level will be reduced to at least the

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TM 5-811-6

recommended maximum levels of OSHA. Use of fansilencers, compressor silencers, mufflers on internalcombustion engines, and acoustical material is re-quired as discussed in TM 5-805-4/AFM88-37/NAVFAC DM-3.1O and TM 5-805-9/AFM88-20/NAVFAC DM-3.14. Consideration should begiven to locating forced draft fans in acousticallytreated fan rooms since they are usually the largestnoise source in a power plant. Control valves will bedesigned to limit noise emissions.

(18) A central vacuum cleaning system shouldbe considered to permit easy maintenance of plant.

(19) Color schemes will be psychologically rest-ful except where danger must be highlighted withspecial bright primary colors.

(20) Each equipment item will be clearly la-belled in block letters identifying it both by equipment item number and name. A complete, coordi-nated system of pipe markers will be used for identi-fication of each separate cycle and power plant serv-ice system. All switches, controls, and devices on allcontrol panels will be labelled using the identicalnames shown on equipment or remote devices beingcontrolled.

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TM 5-811-6

CHAPTER 3

STEAM TURBINE POWER PLANT DESIGN

Section 1. TYPICAL PLANTS AND CYCLES

3-1. Introductiona. Definition. The cycle of a steam power plant is

the group of interconnected major equipment com-ponents selected for optimum thermodynamic char-acteristics, including pressure, temperatures and ca-pacities, and integrated into a practical arrange-ment to serve the electrical (and sometimes by-prod-uct steam) requirements of a particular project. Se-lection of the optimum cycle depends upon plantsize, cost of money, fuel costs, non-fuel operatingcosts, and maintenance costs.

b. Steam conditions. Typical cycles for the prob-able size and type of steam power plants at Army es-tablishments will be supplied by superheated steamgenerated at pressures and temperatures between600 psig (at 750 to 850F) and 1450 psig (at 850 to950 F). Reheat is never offered for turbine genera-tors of less than 50 MW and, hence, is not applicablein this manual.

c. Steam turbine prime movers. The steam tur-bine prime mover, for rated capacity limits of 5000kW to 30,000 kW, will be a multi-stage, multi-valveunit, either back pressure or condensing. Smallerturbines, especially under 1000 kW rated capacity,may be single stage units because of lower first costand simplicity. Single stage turbines, either backpressure or condensing, are not equipped with ex-traction openings.

d. Back pressure turbines. Back pressure turbineunits usually exhaust at pressures between 250 psigand 15 psig with one or two controlled or uncon-trolled extractions. However, there is a significantprice difference between controlled and uncontrolledextraction turbines, the former being more expen-sive. Controlled extraction is normally appliedwhere the bleed steam is exported to process or dis-trict heat users.

e. Condensing turbines. Condensing units ex-haust at pressures between 1 inch of mercury abso-lute (Hga) and 5 inches Hga, with up to two con-trolled, or up to five uncontrolled, extractions.

3-2. Plant function and purposea. Integration into general planning. General

plant design parameters will be in accordance withoverall criteria established in the feasibility study or

planning criteria on which the technical and econom-ic feasibility is based. The sizes and characteristicsof the loads to be supplied by the power plant, in-cluding peak loads, load factors, allowances for fu-ture growth, the requirements for reliability, andthe criteria for fuel, energy, and general economy,will be determined or verified by the designer andapproved by appropriate authority in advance of thefinal design for the project.

b. Selection of cycle conditions. Choice of steamconditions, types and sizes of steam generators andturbine prime movers, and extraction pressures de-pend on the function or purpose for which the plantis intended. Generally, these basic criteria shouldhave already been established in the technical andeconomic feasibility studies, but if all such criteriahave not been so established, the designer will selectthe parameters to suit the intended use.

c. Coeneration plants. Back pressure and con-trolled extraction/condensing cycles are attractiveand applicable to a cogeneration plant, which is de-fined as a power plant simultaneously supplyingeither electric power or mechanical energy and heatenergy (para. 3-4).

d. Simple condensing cycles. Straight condensingcycles, or condensing units with uncontrolled ex-tractions are applicable to plants or situationswhere security or isolation from public utility powersupply is more important than lowest power cost.Because of their higher heat rates and operatingcosts per unit output, it is not likely that simple con-densing cycles will be economically justified for amilitary power plant application as compared withthat associated with public utility purchased powercosts. A schematic diagram of a simple condensingcycle is shown on Figure 3-1.

3-3. Steam power cycle economya. Introduction. Maximum overall efficiency and

economy of a steam power cycle are the principal de-sign criteria for plant selection and design. In gener-al, better efficiency, or lower heat rate, is accom-panied by higher costs for initial investment, opera-tion and maintenance. However, more efficientcycles are more complex and may be less reliable perunit of capacity or investment cost than simpler and

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TM 5-611-6

N A V F A C D M 3Figure 3-1. Typical straight condensing cycle.

less efficient cycles. Efficiency characteristics canbe listed as follows:

(1) Higher steam pressures and temperaturescontribute to better, or lower, heat rates.

(2) For condensing cycles, lower back pressuresincrease efficiency except that for each particularturbine unit there is a crossover point where lower-ing back pressure further will commence to decreaseefficiency because the incremental exhaust loss ef-fect is greater than the incremental increase in avail-able energy.

(3) The use of stage or regenerative feedwatercycles improves heat rates, with greater improve-ment corresponding to larger numbers of such heat-ers. In a regenerative cycle, there is also a thermody-namic crossover point where lowering of an extrac-tion pressure causes less steam to flow through theextraction piping to the feedwater heaters, reducingthe feedwater temperature. There is also a limit tothe number of stages of extraction/feedwater heat-ing which may be economically added to the cycle.This occurs when additional cycle efficiency no long-er justifies the increased capital cost.

(4) Larger turbine generator units are generallymore efficient that smaller units.

(5) Multi-stage and multi-valve turbines aremore economical than single stage or single valvemachines.

(6) Steam generators of more elaborate design,or with heat saving accessory equipment are moreefficient.

b. Heat rate units and definitions. The economyor efficiency of a steam power plant cycle is ex-

3-2

pressed in terms of heat rate, which is total thermalinput to the cycle divided by the electrical output ofthe units. Units are Btu/kWh.

(1) Conversion to cycle efficiency, as the ratio ofoutput to input energy, may be made by dividingthe heat content of one kWh, equivalent to 3412.14Btu by the heat rate, as defined. Efficiencies are sel- dom used to express overall plant or cycle perform-ance, although efficiencies of individual compo-nents, such as pumps or steam generators, are com-monly used.

(2) Power cycle economy for particular plants orstations is sometimes expressed in terms of poundsof steam per kilowatt hour, but such a parameter isnot readily comparable to other plants or cycles andomits steam generator efficiency.

(3) For mechanical drive turbines, heat ratesare sometimes expressed in Btu per hp-hour, exclud-ing losses for the driven machine. One horsepowerhour is equivalent to 2544.43 Btu.

c. Heat rate applications. In relation to steampower plant cycles, several types or definitions ofheat rates are used:

(1) The turbine heat rate for a regenerative tur-bine is defined as the heat consumption of the tur-bine in terms of heat energy in steam supplied bythe steam generator, minus the heat in the feedwa-ter as warmed by turbine extraction, divided bythe electrical output at the generator terminals.This definition includes mechanical and electricallosses of the generator and turbine auxiliary sys-tems, but excludes boiler inefficiencies and pumpinglosses and loads. The turbine heat rate is useful for

TM 5-811-6

performing engineering and economic comparisonsof various turbine designs. Table 3-1 provides theo-retical turbine steam rates for typical steam throttle

conditions. Actual steam rates are obtained by di-viding the theoretical steam rate by the turbine effi-ciency. Typical turbine efficiencies are provided onFigure 3-2.

ASR =where: ASR = actual steam rate (lb/kWh)

TSR = theoretical steam rate (l/kWh)nt = turbine efficiency

Turbine heat rate can be obtained by multiplyingthe actual steam rate by the enthalpy change acrossthe turbine (throttle enthalpy - extraction or ex-haust enthalpy).

Ct = ASR(hl h2)where = turbine heat rate (Btu/kWh)

ASR = actual steam rate lb/kWh)h1 = throttle enthalpyh1 = extraction or exhaust enthalpy

TSR

FROM STANDARD HANDBOOK FOR MECHANICALENGINEERS BY MARKS. COPYRIGHT 1967,

. MCGRAW-HILL BOOK CO. USED WITH THEPERMISSION OF MCGRAW- HILL BOOK COMPANY.

Figure 3-2. Turbine efficiencies vs. capacity.m

(2) Plant heat rates include inefficiencies andlosses external to the turbine generator, principally

the inefficiencies of the steam generator and pipingsystems; cycle auxiliary losses inherent in power re-quired for pumps and fans; and related energy usessuch as for soot blowing, air compression, and simi-lar services.

(3) Both turbine and plant heat rates, as above,are usually based on calculations of cycle perform-ance at specified steady state loads and well defined,optimum operating conditions. Such heat rates areseldom achieved in practice except under controlledor test conditions.

(4) Plant operating heat rates are long termaverage actual heat rates and include other suchlosses and energy uses as non-cycle auxiliaries,

plant lighting, air conditioning and heating, generalwater supply, startup and shutdown losses, fuel de-terioration losses, and related items. The gradualand inevitable deterioration of equipment, and fail-ure to operate at optimum conditions, are reflectedin plant operating heat rate data.

d. Plant economy calculations. Calculations, esti-mates, and predictions of steam plant performancewill allow for all normal and expected losses andloads and should, therefore, reflect predictions ofmonthly or annual net operating heat rates andcosts. Electric and district heating distributionlosses are not usually charged to the power plantbut should be recognized and allowed for in capacityand cost analyses. The designer is required to devel-op and optimize a cycle heat balance during the con-ceptual or preliminary design phase of the project.The heat balance depicts, on a simplified flow dia-gram of the cycle, all significant fluid mass flowrates, fluid pressures and temperatures, fluid en-thalpies, electric power output, and calculated cycleheat rates based on these factors. A heat balance isusually developed for various increments of plantload (i.e., 25%, 50%, 75%, 100% and VWO (valveswide open)). Computer programs have been devel-oped which can quickly optimize a particular cycleheat rate using iterative heat balance calculations.Use of such a program should be considered.

e. Cogeneration performance. There is no gener-ally accepted method of defining the energy effi-ciency or heat rates of cogeneration cycles. Variousmethods are used, and any rational method is valid.The difference in value (per Btu) between prime en-ergy (i.e., electric power) and secondary or low levelenergy (heating steam) should be recognized. Referto discussion of cogeneration cycles below.

3-4. Cogeneration cyclesa. Definition. In steam power plant practice, co-

generation normally describes an arrangementwhereby high pressure steam is passed through aturbine prime mover to produce electrical power,and thence from the turbine exhaust (or extraction)opening to a lower pressure steam (or heat) distribu-tion system for general heating, refrigeration, orprocess use.

b. Common medium. Steam power cycles are par-ticularly applicable to cogeneration situations be-cause the actual cycle medium, steam, is also a con-venient medium for area distribution of heat.

(1) The choice of the steam distribution pres-sure will be a balance between the costs of distribu-tion which are slightly lower at high pressure, andthe gain in electrical power output by selection of alower turbine exhaust or extraction pressure.

(2) Often the early selection of a relatively low

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TM 5-811-6

3-4

steam distribution pressure is easily accommodatedin the design of distribution and utilization systems,whereas the hasty selection of a relatively highsteam distribution pressure may not be recognizedas a distinct economic penalty on the steam powerplant cycle.

(3) Hot water heat distribution may also be ap-plicable as a district heating medium with the hotwater being cooled in the utilization equipment andreturned to the power plant for reheating in a heatexchange with exhaust (or extraction) steam.

c. Relative economy. When the exhaust (or ex-traction) steam from a cogeneration plant can beutilized for heating, refrigeration, or process pur-poses in reasonable phase with the required electricpower load, there is a marked economy of fuel ener-gy because the major condensing loss of the conven-tional steam power plant (Rankine) cycle is avoided.If a good balance can be attained, up to 75 percent ofthe total fuel energy can be utilized as comparedwith about 40 percent for the best and largest Ran-kine cycle plants and about 25 to 30 percent forsmall Rankine cycle systems.

d. Cycle types. The two major steam power cogen-eration cycles, which may be combined in the sameplant or establishment, are:

TM 5-811-6

(1) Back pressure cycle. In this type of plant,the entire flow to the turbine is exhausted (or ex-tracted) for heating steam use. This cycle is themore effective for heat economy and for relativelylower cost of turbine equipment, because the primemover is smaller and simpler and requires no con-denser and circulating water system. Back pressureturbine generators are limited in electrical output bythe amount of exhaust steam required by the heatload and are often governed by the exhaust steamload. They, therefore, usually operate in electricalparallel with other generators.

(2) Extraction-condensing cycles. Where theelectrical demand does not correspond to the heatdemand, or where the electrical load must be carriedat times of very low (or zero) heat demand, then con-densing-controlled extraction steam turbine primemovers as shown in Figure 3-3 may be applicable.Such a turbine is arranged to carry a specified elec-trical capacity either by a simple condensing cycleor a combination of extraction and condensing.While very flexible, the extraction machine is rela-tively complicated, requires complete condensingand heat rejection equipment, and must always passa critical minimum flow of steam to its condenser tocool the low pressure buckets.

.

.

N A V F A C D M 3 Figure 3-3. Typical condensing-controlled extinction cycle.

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TM 5-811-6

e. Criteria for cogeneration. For minimum eco-nomic feasibility, cogeneration cycles will meet thefollowing criteria:

(1) Load balance. There should be a reasonablybalanced relationship between the peak and normalrequirements for electric power and heat. Thepeak/normal ratio should not exceed 2:1.

(2) Load coincidence. There should be a fairlyhigh coincidence, not less than 70%, of time andquantity demands for electrical power and heat.

(3) Size. While there is no absolute minimumsize of steam power plant which can be built for co-generation, a conventional steam (cogeneration)plant will be practical and economical only abovesome minimum size or capacity, below which othertypes of cogeneration, diesel or gas turbine becomemore economical and convenient.

(4) Distribution medium. Any cogenerationplant will be more effective and economical if theheat distribution medium is chosen at the lowestpossible steam pressure or lowest possible hot watertemperature. The power energy delivered by the tur-bine is highest when the exhaust steam pressure islowest. Substantial cycle improvement can be madeby selecting an exhaust steam pressure of 40 psigrather than 125 psig, for example. Hot water heatdistribution will also be considered where practicalor convenient, because hot water temperatures of200 to 240 F can be delivered with exhaust steampressure as low as 20 to 50 psig. The balance be-tween distribution system and heat exchangercosts, and power cycle effectiveness will be opti-mized.

3-5. Selection of cycle steam conditionsa. Balanced costs and economy. For a new or iso-

lated plant, the choice of initial steam conditionsshould be a balance between enhanced operatingeconomy at higher pressures and temperatures, andgenerally lower first costs and less difficult opera-tion at lower pressures and temperatures. Realisticprojections of future fuel costs may tend to justifyhigher pressures and temperatures, but such factorsas lower availability y, higher maintenance costs,more difficult operation, and more elaborate watertreatment will also be considered.

b. Extension of existing plant. Where a newsteam power plant is to be installed near an existingsteam power or steam generation plant, careful con-sideration will be given to extending or parallelingthe existing initial steam generating conditions. Ifexisting steam generators are simply not usable inthe new plant cycle, it may be appropriate to retirethem or to retain them for emergency or standbyservice only. If boilers are retained for standby serv-ice only, steps will be taken in the project design for

protection against internal corrosion.c. Special considerations. Where the special cir-

cumstances of the establishment to be served aresignificant factors in power cycle selection, the fol- lowing considerations may apply:

(1) Electrical isolation. Where the proposedplant is not to be interconnected with any local elec-tric utility service, the selection of a simpler, lowerpressure plant may be indicated for easier operationand better reliability y.

(2) Geographic isolation. Plants to be installedat great distances from sources of spare parts, main-tenance services, and operating supplies may re- quire special consideration of simplified cycles, re-dundant capacity and equipment, and highest prac-tical reliability. Special maintenance tools and facil- ities may be required, the cost of which would be af-fected by the basic cycle design.

(3) Weather conditions. Plants to be installedunder extreme weather conditions will require spe-cial consideration of weather protection, reliability,and redundancy. Heat rejection requires special de-sign consideration in either very hot or very coldweather conditions. For arctic weather conditions,circulating hot water for the heat distribution medi-um has many advantages over steam, and the use ofan antifreeze solution in lieu of pure water as a dis- tribution medium should receive consideration.

3-6. Cycle equipmenta. General requirements. In addition to the prime

movers, alternators, and steam generators, a com-plete power plant cycle includes a number of second-ary elements which affect the economy and perform-ance of the plant.

b. Major equipment. Refer to other parts of this manual for detailed information on steam turbinedriven electric generators and steam generators.

c. Secondary cycle elements. Other equipmentitems affecting cycle performance, but subordinateto the steam generators and turbine generators, arealso described in other parts of this chapter.

3-7. Steam power plant arrangementa. General. Small units utilize the transverse ar-

rangement in the turbine generator bay while thelarger utility units are very long and require end-to-end arrangement of the turbine generators.

b. Typical small plants. Figures 3-4 and 3-6 showtypical transverse small plant arrangements. Smallunits less than 5000 kW may have the condensers atthe same level as the turbine generator for economyas shown in Figure 3-4. Figure 3-6 indicates thecritical turbine room bay dimensions and the basicoverall dimensions for the small power plants shownin Figure 3-5.

TM 5-811-6

U. S. Army Corps of Engineers

Figure 3-4. Typical small 2-unit powerplant A.

3-7

TM 5-811-6

a

3-8

TM 5-811-6

Section Il. STEAM GENERATORS AND AUXILIARY SYSTEMS.

tors for a steam power plant can be classified bytype of fuel, by unit size, and by final steam condi-tion. Units can also be classified by type of draft, bymethod of assembly, by degree of weather protec-tion and by load factor application.

(1) Fuel, general. Type of fuel has a major im-pact on the general plant design in addition to thesteam generator. Fuel selection may be dictated byconsiderations of policy and external circumstances

3-8. Steam generator conventionaltypes and characteristics

a. Introduction. Number, size, and outlet steam-ing conditions of the steam generators will be as de-termined in planning studies and confirmed in the fi-nal project criteria prior to plant design activities.Note general criteria given in Section I of this chapter under discussion of typical plants and cycles.

b. Types and classes. Conventional steam genera-.!

.

AND CONDENSER SUPPLIERS SELECTED.

36433116611.37 . 53 . 71.25 . 5517.55811

NOTE:

U S .

DIMENSIONS IN TABLE ARE APPLICABLE TO FIG. 3-5

Army Corps of Engineers

Figure 3-6. Critical turbine room bay and power plant B dimensions.

3-9

TM 5-811-6

unrelated to plant costs, convenience, or location.Units designed for solid fuels (coal, lignite, or solidwaste) or designed for combinations of solid, liquid,and gaseous fuel are larger and more complex thanunits designed for fuel oil or fuel gas only.

(2) Fuel coal. The qualities or characteristics ofparticular coal fuels having significant impact onsteam generator design and arrangement are: heat-ing value, ash content, ash fusion temperature, fri-ability, grindability, moisture, and volatile contentas shown in Table 3-2. For spreader stoker firing,the size, gradation, or mixture of particle sizes affect

Table 3-2.Characteristic

stoker and grate selection, performance, and main-tenance. For pulverized coal firing, grindability is amajor consideration, and moisture content before and after local preparation must be considered. Coalburning equipment and related parts of the steamgenerator will be specified to match the specificcharacteristics of a preselected coal fuel as well asthey can be determined at the time of design.

(3) Unit sizes. Larger numbers of smaller steamgenerators will tend to improve plant reliability andflexibility for maintenance. Smaller numbers of larg-er steam generators will result in lower first costs

Fuel Characteristcs.Effects

Coal

Heat balance.

Handling and efficiency loss.Ignition and theoretical air.Freight, storage, handling, air pollution.Slagging, allowable heat release,allowable furnace exit gas temperature.Heat balance, fuel cost.Handling and storage.Crushing and pulverizing.Crushing , segregation, and spreadingover fuel bed.Allowable temp. of metal contactingflue gas; removal from flue gas.

Oil

Heat balance.Fuel cost.Preheating, pumping, firing.Pumping and metering.Vapor locking of pump suction.Heat balance, fuel cost.Allowable temp. of metal contactingflue gas; removal from flue gas.

Gas

Heat balance.Pressure, f ir ing, fuel cost .Metering.Heat balance, fuel cost.Insignificant.

NAVFAC DM3

3-10

TM 5-811-6

per unit of capacity and may permit the use of de-sign features and arrangements not available onsmaller units. Larger units are inherently more effi-cient, and will normally have more efficient draftfans, better steam temperature control, and bettercontrol of steam solids.

(4) Final steam conditions. Desired pressureand temperature of the superheater outlet steam(and to a lesser extent feedwater temperature) willhave a marked effect on the design and cost of asteam generator. The higher the pressure the heav-ier the pressure parts, and the higher the steam tem-perature the greater the superheater surface areaand the more costly the tube material. In addition tothis, however, boiler natural circulation problems in-crease with higher pressures because the densitiesof the saturated water and steam approach each oth-er. In consequence, higher pressure boilers requiremore height and generally are of different designthan boilers of 200 psig and less as used for generalspace heating and process application.

(5) Type of draft.(a) Balanced draft. Steam generators for elec-

tric generating stations are usually of the so calledbalanced draft type with both forced and induceddraft fans. This type of draft system uses one ormore forced draft fans to supply combustion air un-

der pressure to the burners (or under the grate) andone or more induced draft fans to carry the hot com-bustion gases from the furnace to the atmosphere; aslightly negative pressure is maintained in the fur-nace by the induced draft fans so that any gas leak-age will be into rather than out of the furnace. Nat-ural draft will be utilized to take care of the chimneyor stack resistance while the remainder of the draftfriction from the furnace to the chimney entrance ishandled by the induced draft fans.

(b) Choice of draft. Except for special casessuch as for an overseas power plant in low cost fuelareas, balanced draft, steam generators will be spec-ified for steam electric generating stations.

(6) Method of assembly. A major division ofsteam generators is made between packaged or fac-tory assembled units and larger field erected units.Factory assembled units are usually designed forconvenient shipment by railroad or motor truck,complete with pressure parts, supporting structure,and enclosure in one or a few assemblies. Theseunits are characteristically bottom supported, whilethe larger and more complex power steam gener-ators are field erected, usually top supported.

(7) Degree of weather protection. For all typesand sizes of steam generators, a choice must bemade between indoor, outdoor and semi-outdoor in-stallation. An outdoor installation is usually less ex-pensive in first cost which permits a reduced general

building construction costs. Aesthetic, environmen-tal, or weather conditions may require indoor instal-lation, although outdoors units have been used SUC- cessfully in a variety of cold or otherwise hostile cli-mates. In climates sub